ML20100B323
| ML20100B323 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 12/03/1984 |
| From: | Oneill J CAROLINA POWER & LIGHT CO., SHAW, PITTMAN, POTTS & TROWBRIDGE |
| To: | Bright G, Carpenter J, Kelley J Atomic Safety and Licensing Board Panel |
| References | |
| CON-#484-431 OL, NUDOCS 8412040297 | |
| Download: ML20100B323 (336) | |
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- aces,tts p eas mv.'"oin.4 wn.,E a s o.4E CT o, A NeweE m (202)822-1148 December 3, 1984 James L. Kelley, Esquire Mr. Glenn O. Bright Chairman Atomic Safety and Licensing Board Atomic Safety and Licensing Board U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Washington, D.C. 20555 Dr. James H. Carpenter Atomic Safety and Licensing Board U.S. Nuclear Regulatory Commission Washington, D.C. 20555 In the Matter of Carolina Power & Light Company and North Carolina Eastern Municipal Power Agency (Shearon Harris Nuclear Power Plant)
Docket No. 50-400 OL Administrative Judges Kelley, Bright and Carpenter:
During the most recent hearings in the above referenced proceeding Applicants made an oral motion regarding two de-ferred Eddleman contentions on diesel generators. Tr. 6842-50.
The Board requested that Applicants supplement the motion by informing the Board "the extent to which the Commission or the Appeal Board or other Boards have signed on the safety aspects of other [Transamerica Delaval, Inc. ("TDI") DSRV-16 diesel generator engines}, except Catawba." Tr. 6850. Off the record, the Board also requested the ratings and loads of other DSRV-16 diesel generators.
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SHAw, PITTMAN, PoTTs, & TROWBRIDGE A PARTNER $MIP OF PROFESSIONAL CCRPORATIONS l~ Letter to the Administrative Judges December 3,.1984 Page 2 Three nuclear plants with TDI DSRV-16 diesel generators are further along in the licensing process.than Harris --
Mississippi Power and Light Company's Grand Gulf Nuclear Sta-tion Unit 1 :(" Grand Gulf"), Duke Power Company's Catawba Nucle-ar Station, Unit.1 (" Catawba") and Texas Utilities Generating Company's Comanche Peak Steam Electric Station, Unit 1
(" Comanche Peak"). A contention with respect to the reliability of TDI diesel generators has not been litigated in any of the three proceedings.
The Commission voted to authorize the NRC-Staff to issue a full power operating license for Grand Gulf on July 31, 1984.
The Grand Gulf operating license was not contested. However, the Commission received a detailed briefing on the diesel gen-erators prior to voting to authorize the full power license. A copy of the relevant pages from the transcript of the Commis-sion meeting of July 31, 1984 is attached hereto as Attachment
- 1. In approving full power operations, Chairman Palladino noted that: "the NRC Staff has determined that the emergency on-site diesel generators are reliable to perform their intend-ed function if needed." Tr. 108 (July 31, 1984 Meeting).
I certain admitted contentions in Comanche Peak are still before the Atomic Safety and Licensing Board in that'procead-
. ing. While there has not been a contention admitted on diesel :
generator reliability, the Comanche Peak Board did request cer-tain information from the applicant regarding TDI diesel gener-ators in reference to an admitted contention on quality assur-ance. Counsel for the applicant in Comanche Peak informs me that there has been no resolution'of that issue. As this Board j is aware, contentions relating to diesel generators in the Ca-i tawba proceeding were dismissed.
i l
In all three of the above-mentioned proceedings, a Safety Evaluation Report ("SER") on the reliability of diesel genera-tors has been issued by the NRC Staff. A copy of the three SER's is enclosed as Attachments 2, 3 and 4. i i
L i t-L - - .. _ _ __ - _. __ __ , . . _ . _ . _ _ _ _ . - . _ _ _ . _ _ _ _ _ _ _ . . . _._..
I SHAw. PITTMAN, PoTTs & TROWBRIDGE A DARTNERSHIP OF PROFESSIONAL CORDORAflONS Letter to the Administrative Judges December 3, 1984 ;
Page 3 Finally, appended as Attachment 5 is a table providing comparative ratings and loads of the diesel generators at Grand Gulf, Comanche Peak, Catawba and Harris. Except for the Harris Plant, the information in the enclosed table was obtained from the Diesel Generator Owners' Group. While all four plants pur-chased virtually identical diesel engines (as indicated by the rating parameters), the Harris Plant required a somewhat lower design output from the manufacturer. The lower rating is not, however, due to a design difference in the engine but rather reflects the design specifications of Applicants and the KW output commitment from the manufacturer. In other words, TDI supplied for Harris engines actually capable of 7000 KW output with a slightly different generator to meet Applicants' 6500 KW design requirement.
Re ect bily s bmittevl, ,
i John O'Neill, Jr., P.C.
Couns{H.
el for Applicants cc: Attached Service List
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION l
BEFORE THE ATOMIC SAFETY AND LICENSING BOARD 1
In the Matter of )
)
CAROLINA POWER & LIGHT COMPANY ) Docket No. 50-400 OL and NORTH CAROLINA EASTERN )
MUNICIPAL POWER AGENCY )
)
(Shearon Harris Nuclear Power )
Plant) )
SERVICE LIST James L. Kelley, Esquire John D. Runkle, Esquire Atomic Safety and Licensing Board Conservation Council of U.S. Nuclear Regulatory Commission North Carolina Washington, D.C. 20555 307 Granville Road Chapel Hill, North Carolina 27514 4
Mr. Glenn O. Bright M. Travis Payne, Esquire Atomic Safety and Licensing Board Edelstein and Payne U.S. Nuclear Regulatory Commission P.O. Box 12607 Washington, D.C. 20555 Raleigh, North Carolina 27605 Dr. James H. Carpenter Dr. Richard D. Wilson Atomic Safety and Licensing Board 729 Hunter Street U.S. Nuclear Regulatory Commission Apex, North Carolina 27502 Washington, D.C. 20555 Charles A. Barth, Esquire Mr. Wells Eddleman Janice E. Moore, Escuire 718-A Iredell Street Office of Executive Legal Director Durham, North Carolina 27705 U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Docketing and Service Section Richard E. Jones, Esquire Office of the Secretary Vice President and Senior Counsel U.S. Nuclear Regulatory Commission Carolina Power & Light Company Washington, D.C. 20555 P.O. Box 1551 Raleigh, North Carolina 27602 Mr. Daniel F. Read, President Dr. Linda W. Little CHANGE Governor's Waste Management Board P.O. Box 2151 513 Albemarle Building j
Raleigh, North Carolina 27602 325 North Salisbury Street Raleigh, North Carolina 27611
.. g .
.t Bradley W. Jones, Esquire U.S. Nuclear Regulatory Commission l Region II 101 Marrietta Street Atlanta, Georgia 30303 Steven F..Crockett, Esquire Atomic Safety and Licensing Board Panel U.S. Nuclear. Regulatory Commission Washington, D.C. 20555 Mr. Robert P. Gruber Executive Director Public Staff - NCUC P.O. Box 991 Raleigh, North Carolina 27602 Administrative Judge Harry Foreman Box 395 Mayo University of Minnesota Minneapolis, Minnesota 55455 i
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Attachnent 1 i
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UNITED STATES NUCLEAR REGULATORY COMMISSION REFER TO: M8407313
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'84 AUG 16 A8:53 PU BLli, -- -
MEMORANDUM FOR: William J. Dircks, Executive Director for Operations
FROM: Samuel J. Chilk, Secretary
. I a
SUBJECT:
STAFF REQUIREMENTS - DISCUS $ ION /POSSIBLE VOTE ON FULL POWER OPERATINC. LICENSE FOR GRAND GULF, 11:00 A.M., TDE$ DAY, JCLY 31, 1984, COMMISSIONERS' CONFER 2NCE ROOM, D.C. OFFICE (OPEN TO PUBLIC ATTENDANCE)
The Cc=issica me: to be briefed by staff and by represen-tatives of Mississippi Pcwer and Licht Com:any en the readiness fer a FPOL at Grand Gulf nit 1.'
The Cc==ission voted 4-0 (Oc=issioner Asselstine abstaining) to authorize staff to issue the full power Operating license
, amendment.
j (NRR) s cc: Chairman Palladino Cc=issioner Roberts e Comm.irssioner Asselstine
. Commissioner Bernthal Commissioner Zach
. Commission Staff Offices DR - Advance i CS - 016 Phillips
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d UNITED STATES CF AMERICA 2
NUCLEAR REGULATCRY CCMMISSICN 3
4 5
In the Matter of:
6 7
8 9
DISCUSSICN AND VCTE CN FULL PC' DER OPEP.ATING LICENSE 10 FOR GRAND GULF 11 12 13 14 15 CPEN MEETING 16 17 Location: '4a s hing to n , D . C . Pages: 1 - 114 Date: Tuesday, July.31, 1984 20 21 22 23 24 25
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' UNITED STATES OF AMERICA 2
NUCLEAR REGULATORY COMMISSION 1
3 DISCUSSION ON FULL.PCWER OPERATING LICENSE FOR GRAND GULF 5
OPEN MEETING 6
Nuclear Regulatory Commission 7
1717 H Street, N.W.
Room 1130 8 Washington, D.C.
9 July 31, 1984 10 The Commission met, pursuant to notice, at 11 11:00 a.m.
12 COMMISSIONERS PRESE"T:
13 NUNZIO PALLADINO, Chairman of the Commission THOMAS ROBERTS, Commissioner 14 JAMES ASSELSTINE, Commissi:ner FREDERICK BERNTHAL, Commissioner 15 LANDO ZECH, JR., Commissioner 16 STAFF AND PRESENTERS SEATED AT COMMISSION TABLE:
17 S. Chilk, Secretary 18 H. Plaine, General Counsel D..Eisenhut 19 H. Denton W. Dircks 20 J. O'Reilly M. Malsch 21 W. Cavinaw W. Johnston 22 T. Novac D. Lewis 23 8. Wilson J. O'Shinski 24 A. Wagner G. Hollihan 25 H. Thompson Dr. Dengy Dr. Berlinger FREE STATI REPORTING INC.
cemet aseeetene e cepeestion.
D.C. Atee 141 1901 e Belt. & Annep. 149-4134
t DISCLAIM E 2
This is an unofficial transcript of a meeting of 3
the United States Nuclear Regulatory Commissien held on July 31, 1984 in the Commission office at 17J7 H.
4 S t re e t, N.W., Wa sh in g to n, D.C. The meeting was open to public attendance and observation. This transcript has 5
not been reviewed, corrected, or edited, and it may contain inaccuracies.
The transcript is intended solely for general 7
informational purposes. As provided by 10 CFR 9.10 3, it is not part of the formal or informal record of
, decision of the matters discussed. Expressions of opinion in this transcript do not necessarily reflect
, the final determinations or beliefs. No pleading or other paper may be filed with the Commission in any proceeding as the result of or addressed to any 10 statement or argument contained herein, except as the Commission may authori::e.
12 13 14 15 16 17 18 19 20 21 22 23 24 25
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PRM STATI REPORTING INC.
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of standardized tech specs plant design.
2 MR. EISENHUT: If I could go on to slide number 3
nine, skip by the next two slides on tech specs, the 4
next issue I'd like to address is Transamerica diesel 5
valve, diesel generator.
6 It's really the diesel. In January of this year, 7
we had a generic meeting with a number of owners, the a
owners of the TDI Diesels, and we reached the conclusion at that point, we really didn't have enough confidence to go forth in making licensing decisions with TDI diesels without some additional work.
12 Earlier this year, the owners group put together,
'3 they had even at that time started putting together a, very concerted, major effort to get their hands around 15 this problem.
16 The staff had developed and put together a project group. Let me give you she bottom line, and then I'd like to have the head of our staff project group on the staff here give you a short summary.
20 We believe the progress is developed to date with 21 the programs and inspections and the reworks, we are 22 now confidence that these diesels at Grand Gulf satisfy 23 the requirements.
24 With that sort of an overview, I'd like to turn it 25 over to Dr. Carl Burlinger of the staff, who is the PRM STATI REP 0ATING INC.
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staff director of the project group we set up earlier 2
this year to bring this review together in a 3
concentrated effort.
DR. BERLINGER: Good morning. The TDI Project 5
Group was formed, as Darrell said, in January. 'de have a
several staff members in-house, primary function is to coordinate the review ef fort, but the primary technical a
review work is being performed for the staff on the 8
contract with Battelle, Pacific Northwest Laboratory.
10 Sattelle has put together a program and a 11 representative of Battelle is here. I'll give him an 12 opportunity to describe his organization and some of 13 the efforts that they have been pe,rforming on behalf of 14 the staff.
15 '4 hat I'd like to take an opportunity to describe 16 for you at the present' time is the inspection which was 17 ordered to be conducted in an order dated May 22nd.
'8 The need for the inspection stems from a review 18 conducted by our contractor at Battelle. Their review 20 of information provided by the licensee which built 21 upon what appeared in January and February to be a void 22 of information with regard to reliability of these 23 engines, was conducted in such a way that the owners 24 group had provided some information at a point in time 25 such as April of this year, '84 PRM STATE REPORTING INC.
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l 26 That information was, in fact, either just recently I
suomitted from the standpoint of eight out of a planned 16 technical reports had been received by the staff.
4 But the staff had not had an opportunity to get I
into the review of those reports to any great degree, I
and the particular inspections which had been conducted at the Grand Gulf nuclear plant in January and early a
February of '84 had, in fact, been visual examinations.
They had not been detailed, non-destructive
'O examinations. They had not been the type of
inspections which had been recommended in some of the 12 reports that the owners group had submitted to the
'3 staff for review. ,
In fact, some of the owners gr:ap reports which had is been submitted in March and early April had 16 recommended inspections be performed which, in fact,
'I were clearly not done on either particular components which we deemed critical or in fact, the methods of inspection that had been used on these inspections of 20 parts had, in fact, been far less than what the owners 21 group or the staff felt was adequate.
22 In addition, there were many parts within the 23 engine which had been operated. They had been operated 24 for a number of--several hundred hours, as a minimum, 25 and to date, some of these components have amassed IM STATE MPORTING INC.
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O i 27 1,100 to 1,300 hours0.00347 days <br />0.0833 hours <br />4.960317e-4 weeks <br />1.1415e-4 months <br /> of operation. Several critical components had never been non-destructively examined since they had been put into operation.
4 These included pistons, connecting rod bearings, connecting rods, wrist pin bushings, the engine block, turbocharger, thrust bearings.
These are components which have been identified by a
the owners group in the Phase I program as critical components for which the potential existed for a generic problem.
" They are problems that actually have occurred in 12 nuclear facilities, in some non-nuclear f acilities,
'3 including maring applications and stationary electric power generating units.
15 In addition, there had been inspections which had 16 been performed at both Shoreham and at Kataba. These inspections, if they hadn't been completed 100%, were near completed at the time which we were deliberating with regard to Grand Gulf and the need for further 20 inspection.
21 The deficiencies which have been identified in 22 December and January and specifically discussed with 23 the owners group representatives in January, the 24 deficiencies in the quality assurance and quality 25 control at TDI nad, in fact, made it difficult if not PRM STATI REPORTING INC.
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28 impossible for us to say that the inspections performed at other facilities could, in fact, be applied to Grand Gulf.
4 There are just too many deficiencies for us to be 5
able to show that they were equivalent on a design and construction basis to, say, a plant like Kataba, where they have the same V-16 type engines.
a Okay. At this time, I would like to introduce Dave Dengy, who is with Battelle Northwest Laboratory, and
'O he can give you a description of PNL's involvement since this spring.
12 D r. Dengy is one of the managing personnel in
'3 charge, of this contract at Battelle, and he has brought to the meeting today one of our diesel engine 15 consultants, Adam Hendrix, who is employed by Battelle.
16 I'm sure if you have any specific questions during their presentation, they'd be glad to try and answer them for you.
COMMISSIONER ASSELSTINE: Just before you do that, 20 I have more of a general question that maybe you can 21 address and then maybe they can follow up on with U
specifics.
23 As I understood it, the staff response based upon 24 our consultant's expert advice to the owners scoup 25 report was intended to serve as the basis for interim PRM STATI REPORTING INC.
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29 1 l licensing for plants. I gather that there are still a '
2 number of open issues at least as f ar as our expert 3
consultants are concerned regarding the owners group 4
responses in various areas concerning the diesels.
5 I have a couple of them in particular that I'm 6
interested in. The staff is in the position today of 7
saying, "You can go ahead and license Grand Gulf 8
without having reached a resolution on those open 9
items."
'O And I guess what I'm trying to get a sense for is the basis for that judgment in light of the fact that 12 in some areas, at least, the owners group information
'3
, that's been submitted so far hasn't proved to fully resolve all the issues to the staff's satisfaction.
15 MR. DENTON: Commissioner, we're on the verge of 16 approving the overall owners group program and the issues that are lef t, to the extent they apply to Grand
'8 Gulf, have been taken into account. But let me ask Carl to answer that.
20 DR. BERLINGER: Thank you, Harold. The owners 21 group program plan has been under review since it was 22 submitted early March.
23 o The consultants at Pacific Northwest Laboratory 24 have submitted their report, which addresses the 25 rogram plan.
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They have drawn certain conclusions and made ;
2 specific recommendations. That report is in our hands and we are in the pro' cess of finali::ing a staff safety 4
evaluation report which will specifically address the adequacy of the overall owners group program plan to solve and address the entire issue in total.
But in addition, it also addresses the owners group a
proposal as a basis for interim licensing, interim meaning between now and when the entire owners group
'O program plan has been completed and implemented, all
" the recommendations from both the owners group and the 12 staff have been implemented by the utilities.
'3 The conclusion that.we have drawn at this point in our review, which is basically finished, with reg'ard to 15 program plan, is that although some of the technical 16 reports, we have not completed our review, we feel confident at this stage that we can go forward on the
'8 basis of the technical' analyses that have been submitted as part of their Phase I program.
20 However, that alone cannot stand by itself. The 21 Phase I technical reports really must be supplemented 22 with the tear-down and inspection of one of the engines 23 at each of the installations, to verify the condition 24 of those engines prior to allowing the plant to 25 operate. i l
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In addition, any other diesels at that site which 2
would be depended upon by the utility in the event of 3 '
of f-site power or similar event, would have to be shown 4
to be essentially equivalent in design construction and basically by reviewing the quality assurance records at 6
TDI, the manuf acturer and their own quality assurance 7
and quality control records at the utilities, they are a
being asked to justify that engine B is representative by engine A at a particular site.
'O In addition, there is specific need for enhanced maintenance and surveillance programs. These programs 12 are absolutely necessary to assure that the condition
'3 of the diesels is maintained at a level which we are assured of by the inspection throughout, say, the first is refueling cycle, 18 months.
Basically, we're saying that we can go forward with the licensing of these plants because on the basis of our review and our inspections and maintenance and surveillance programs that have been, especially in the 20 Grand Gulf case, been totally adopted by the utility, 21 that we have an adequate basis that the engines do 22 provide reliable service and satisfy GDC-17.
23 COMMISSIONER ASSELSTINE: So you're basically 24 saying as f ar as the owners group proposal is 25 concerned, at least you have reached a consensus and v
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' our expert consultants have as well, on an interin 2
approach that you believe is satisfactory for a period i
3 of time.
DR. BERLINGER: That is correct. !
5 COMMISSIONER ASSELSTINE: In every area that the a
consultants have concerns about the owners group proposal.
8 DR. BERLINGER: That is correct.
8 And involves not only the COMMISSIONER ASSELSTINE:
30 material that they've submitted, but also the kind of
" inspection that is required in this particular case.
12 D R. BERLINGER: Yes. And it's extremely important
'3 for us in the area of maintenance and surveillance
'd requirements.
'S For instance, surveillance requirements that we 16 have specified be adopted by all of the utilities is what is called a barring over or engine air roll, is and this is conducted prior to. planned operation of the engine, which is done periodically in accordance with 20 tech specs, once a month or every 18 months.
21 The requirement for the air roll is to verify that 22 there are no water jacket leaks into the engine, into 23 the cylinders.
24 So that head cracks or cylinder liner cracks or 25 gasket leaks could be detected and corrected prior to PREE STATE REPORTING INC.
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running the engine and putting it in an undue stressful i situation.
. 3 ,
As a result of an air roll which was conducted )
4 within a last few days prior to some surveillance 5
testing at Grand Gulf, there was water noted in one cylinder, and as a result of this procedure, that cylider head, which was discovered to have a crack in a
it, has been replaced so that this is the type of 8
maintenance and surveillance which we're looking at,
'O which is really a hard type maintenance and
" surveillance, where we monitor lube oil quality to look 12 for problems like bearing wear or look for problems
'3 such as water leaks into the crankcase.
COMMISSIONER ASSELSTINE: There were two areas, in is particular, when I read through the supporting 16 material, that you all had supplied that I was
'7 interested in that seemed particularly relevant to
'8 Grand Gulf.
Cne of them was the crankshaft cracks, and the 20 other was the cylinder head cracks that I guess you 21 just talked about.
22 Was the cylinder head that you found the cracks in 23 in the diesel that was inspected or in the diesel that 24 was not inspected?
25 DR. BERLINGER: I think it was in the Division One
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diesel.
2 COMMISSIONER ASSELSTINE: The one that was
- 3 inspected.
4 DR. BERLINGER: That was inspected.
5 COMMISSIONER ASSELSTINE: Does that mean that that's a new crack that appeared af ter the inspection was done?
s DR. BERLINGER: Not necessarily. The crack occurred in a place which has never been found to have
'O f ailed in the past in any of the TDI engines in nuclear service.
12 And even the records for some of the non-nuclear 33 service, there's no indication that a crack has occurred in a'similar location.
15 The location is really not on the surface, the 16 internal surf ace, within the cylinder cavity. It's back behind in the exhaust port area, behind the valve is seat up into the area where the valve stem is located or passes.
20 It's possible, although we don't have any 21 confirmatory information at this time, that that could 22 have been a casting defect or problem which may have 23 existed but which may not have been leaking in the 24 past.
25 COMMISSIONER ASSELSTINE: Do we know enough about FREE STATE REPORTING INC.
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why the inspection didn't identify this problem to still have confidence in the accuracy and adequacy 3
of the inspection that was done on the Division Cne 4
diesel?
5 DR. SERLINGER: For two reasons. The inspections which we requested were looking for specific problems, and most of the non-destructive examinations that were 8
conducted not only at Grand Gulf but at other utility sites were in those areas where we knew that known 10 problems had occurred before.
" In addition, we are required to do a general
~
12 inspection, which is more than just visual. The
'3 particular crack which occurred in the last few days or has'been identified in the last few days, was in fact 15 not in an obviously visible lccation.
16 In order to observe the crack, you had to use a
'I boroscope techniques to see inside the head.
18 COMMISSIONER ASSELST!.'iE: Do we know enough about
'8 what causes these cracks in the cylinder heads and the 20 crankshafts to be sacisfied that just the inspection of 2' Division One diesel is good enough, that having 22 inspected the Division One diesel and not found these 23 problems, and having been able to relate the 24 manufacturing and QA records of Division Two to 25 Division One, that there's not also a need to conduct PREE STATE REPORTING INC.
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the same kind of inspection for the Division Two I
diesel, particularly now in light of the crack you 3
found in the Division One head?
4 DR. PERLINGER: To respond to your comment and question, it would be appropriate for me to ask Dave Dengy to come up.
COMMISSIONER ASSELSTINE: Okay.
s DR. BERLINGER: That was specifically one of the items in which Battelle provided the staff support.
'O COMMISSIONER ASSELSTINE: I have one other
" question. Let me ask it, and then maybe he can address 12 both of those.
'3 I know that another utility went ahead and took the, step of replacing all of the cylinder heads on tileir V-16 15 diesel.
16
'4 hen I visited that plant, I was told, "Look, we're just not going to fool with it. 'de want to make sure
'8 that we don't have problems in this area. '4e're going
" to replace them all."
20 4hy isn't that the preferred course? I gather it 21 was a redesigned, modified, upgraded cylinder head.
22 DR. BERLINGER: TDI has developed over the years, I 23 think, three cylinder head designs. I think they call 24 them Model 1, 2, and 3 25 COMMISSIONER ASSELSTINE: Yes. These are all ones.
PRM STATI REPORTING INC. I Cane seeeeeene e secesse6ene i D.C. Aree 1411991 e Seet. & Anney. 149 4134 j l
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37 DR. BERLINGER: Pardon?
2 COMMISSIONER ASSELSTINE: These are all ones, 3
right? At Grand Gulf I think that's what...
4 DR. BERLINGER: I don't know f or sure. I think 5
they are. I think they're early models.
COMMISSIONER ASSELSTINE: Yes.
DR. BERLINGER: I think at this time, Dave, I could a
use some details from you.
M R. DENTON: I think it would be useful if you'd
'O describe the composition of your review team and the
" expertise that you've been able to bring to 5 ear on 12 this issue.
'3 I'm Da v e Dengy f rom FNL.
DR. DENGY: The PNL organization was called into this program in late 15 February, early March. At that time we set up an 16 organization consisting of the technical disciplines that we thought would be needed to support the program, is namely, metallurgists,' stress analysts, and non-destructive evaluation experts, as well as leading 20 project engineers throughout the organization to t1ke 21 on various elements of the program.
22 The program was guided by the director's office and 23 we have a senior review board, consisting of three 24 members of the director's of fice, as well as our 25 project manager.
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38 I'm the deputy project manager. And our first task 2
was to bring in the consultants or technical expertise 3
in the diesel engines.
4 It's not something that PNL had, nor do I think any 5
other laboratory has on hand.
" So we went out very aggressively to find consultants both within the U.S. and as far abroad as a
we felt we should go to get an adequate number of diesel experts.
'O At this time, we have about ten individual
" consultants and, I believe, four organizations from 12 England, from Norway, from Canada, and organizations
'3 here in the U.S., as well as the ten individual consultants, many of whom are retired and have the time 15 available to devote and dedicate t0 this program on an 16 extended basis.
The program was then organized to respond
'8 immediately to several tasks at once, one being the owners group plan that was given to us, and we had 20 provided an evaluation of that plan to help NRC provide 21 them a technical basis for establishing an interaction 22 with the owners group regarding that plan.
23 That report was issued recently. It has a section 24 that I think Carl has referred to, that deals with 25 interim licensing.
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39 That is, plants that we knew were coming onstream 2
or would like to come onstream for licensing action 3
before the owners group had completed its program, 4
which program might take still many months for 5
completion.
6 I think he's alluded to or referred to the areas 7
where we felt we could take interim action and what 8
sort of requirements we would need for that.
9 At the came time, we took on the job of looking at 10 plants' specific requests, such as the Mississippi 11 Power & Light request.
12 '
We entered that with the February 20th submittal 13 from Mississippi Power & Lig,ht, where they identified 14 their inspection program, their proposed testing 15 program, and to some extent, a proposed maintenance 16 program.
17 We responded immediately and interacted with NP.C 18 and our consultants at'that time. We brought four 19 consultants in from England, from Norway, two from the 20 U.S. to review that program that Mississippi Power &
21 Light had given us.
22 We felt is was inadequate on a number of bases. We 23 told NRC of the inadequacies and that was subsequently 24 ,
communicated.
25
\
Over a period of several weeks on interactions, we
~
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went to the meetings, attended the meetings between NRC 2 .
and MP&L and participated as needed to form viewpoints 3
on site at those meetings.
4 Subsequently, the order went out to tear *he 5
engine down. That was, of course, in accordance with 6
our recommendations as well.
7
'de attended the engine tear-down inspection, looked e
at the results, and formed our own view and provided 9
NRC with our findings relevant to that tear-down 10 inspection.
11 And so that's sort of the technical basis for the 12 -
kind of organization we have and the technical basis 13 for forming our judgments based on our own staff 14 metallurgists, stress analysts, and consultants, with 15 large emphasis on the consultants' views.
16 CHAIRMAN FALLADINO: Are you satisired that the 17 surveillance program would disclose any cracks in the is head in time enough to ' prevent malfunctioning of the 19 diesel?
20 D R. DENGY: Yes, I am, and the procedure is that 21 after the engine is run, before the engine or just as 22 the engine cools down until it reaches a steady state, 23 any cr:ck: that have been closed because of the thermal 24 expansion would open up.
25 So after about four hours, the first time you can l
l PREE STATI REMHtTING INC.
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-t reasonably get in there and look for cracks, we require 2
the engine barring a roll over, to see if there's any 3
water leaks that have developed.
4
'de then ask that that be done within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and 5
then there is strong confidence beyond that time if a
no cracks develop, that it won't develop subsequently.
7 So then before every plant start, you would go a
through a normal barring over or roll over to make sure 9
that that's true, so it can be--there are three time 10 scales, four hour, 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and then every time before 11 the engine is started.
12 CHAIRM AN PALL ADI:10: '4as the cracked head replaced 13 with a Model 1, 2, or 3?
14 .
DR. DE:lGY: I don't know.
15 CHAIRMAN PALLADING: Do you kn:w?
16 DR. SERLINGER: '4e haven't been provided with 17 enough information to identify specifically the model 18 head that was put in. '
19 CHAIRMAN PALLADINO: I understand that disassembly 20 also disclosed some difficulties with cap screws and 21 turbochargers.
22 Is that significant? I wasn't sure.
23 DR. DENGY: Yes, it was significant, and we had the 24 turbochargers sent back to Elliot for a complete 25 refurbishment. .
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We recommended that, and MP&L subsequently did that 2
to return the turbochargers to essenhially new 3
conditio1.
4 M R. EISENHUT: M r. Chairman, that wasn't something 5
that was Aike this other issue which was found in the 6
last couple of days.
CHAIRMAN PALLADINO: I understand that. That was 8
during the disassembly.
8 DR. DENGY: We reviewed their report on that, and
'O it was a stress corrosion or defect or cracking that occurred in the bolts, and we think there's dequate 12 action taken to prevent that.
'3 We've recommended to NRC that any 1icensing action
'd for the first refueling cycle would be appropriate.
15 COMMISSIONER ASSELSTINE: Does the identification 16 of this new crack in an.y way alter your confidence in the inspection?
18 DR. DENGY: No. The crack occurred in an area, as Carl said, that wasn't normally thought of as an area 20 having any particular stress.
21 And it wasn't part of their original inspection, so 22 not being part of the original inspection, it wouldr.'t 23 have been found.
24 And it isn't one where we would have expected it.
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at this point in time.
It's relatively new to me.
3 COMMISSIONER ASSELSTINE: '4 hat's the basis for your 4
confidence that the inspection from the Division One 5
diesel is sufficient as far as the Division Two diesel?
6 I noted in particular, for example, you talked in 7
your report about the crankshaft failures.
8 One of those you couldn't identify the cause of previous crankshaf t failures. So to what extent can
'O you draw confidence that having inspected Division One,
" that's good enough, as long as you can also trace the 12 quality assurance records and the other records for
'3 Division two as well?
(Note: Commissioner Roberts leaves the meeting at this 15 time.)
16 33, 3 g3g f. .de l l , the basis for accepting Division Two without tear-down inspection was basically it had 18 fewer hours under comparable maintenance and surveillance procedures as engine one, so engine one 20 would have had the most damage, if you will.
21 And there was nothing on engine one tear-down 22 inspection that seemed to suggest that there was a 23 problem, that engine two should be torn down or 24 l
inspected.
25 So that provided we didn't get anything suspicious, 1
l ..
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44 that is, something that looks like, gee, this is a 2
problem peculiar to that particular engine or peculiar 3
to MP&L's maintenance, surveillrnce procedures, and -
4 they could show the adequacy of the records to convince 5
us that engine two and engine one were built to the 6
same specs, hac the same material, quality control, 7
manufacturing, installation quality control,' which they 8
provide us with a report on that, we felt that that tear-down would not be necessary. ,
10 COMMISSIONER ASSELSTINE: Given the fact that most
" all the cracks in the heads have occurred in the group 12 one heads, why isn't it just a prudent thing to do to 13 replace all of the group one heads with the upgraded
'd heads that haven't had the same kind of significant is problems?
16 DR. DENGY: I feel 'that the group one heads have 17 had a reasonable positive survival in other 18 applications, so it's reasonable to expect that they 18 might be acceptable in this application as well.
20 Other utilities have replaced them. It wasn't a 21 requirement.
22 CHAIRMAN PALLADINO: Any more? Okay.
23 M R,: EISENHUT: I'd like to go to the next slide. I 24 put this slide in for consistency. You will recall 25 that in May, there was a SIscreham order, and it turns FREE STATI REPOltTING INC.
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out a couple of days later than that, we informed 3
Mississippi Power and Light of the need for an 4
exemption in connection with the diesel inspection, that we had determined they did not meet GDC-17.
5 We sort of cast that upon them.
6 We also told them at that time to address exigency and as-safe-as. They did file the exemption as we requested. They filed it 8
on June 4, 1984 -
9 10 The staff shortly after starting that review until up until last Wednesday was engaged in a very detailed 11 12 rev iew of as-safe-as, which, to give you an idea on the extreme, we had the utility back redoing those 13 calculations. .
We're to the point where we think, of course, 15 depending on today's meeting, upon the issuance of the 16 17 full power license, the need for that exemption is a moot point, 18 and we would propose no further action be taken on that matter.
19 COMMISSIONER ASSELSTINE:
20 You're conclusion, then, 21 is the plant with these diesel generators meets GDC-17 .
MR. DENTON: }
That's correct.
22 MR. EISENHUT: That is correct.
23 If I can go to the next slide.
24 COMMISSIONER ASSELSTINE:
25 I have one other related question on diesels.
This came out of my visit to the I
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plant. That had to do with the extent of testing that 2
we require these diesels.
3 One of the things I was told by the utility was 4
that the actual load on the diesels at Grand Gulf was 5
about 70%, but that our requirements force them to test 6
these diesels at 110% of capacity.
7 I guess I wondered whether that's something that is 8
being looked at in terms of the overall review of 9
diesel testing requirements.
'O Their point to me was running a diesel engine at 110% of rated capacity puts a great deal of strain on 12 the engine itself and may not be necessary, given the
'3 lower load for that particular plant.
Is that something that you all are looking at as a is general matter?
16 ~
M R. EISENHUT: Yes,. it is, but as a general matter, 17 though, we recognize that the emergency loads on a 18 diesel may only be something on the order of 70%.
19 As time goes on, following an event where you need 20 those, tnere are a number of house loads that normally 21
- get put on to this, or number of non-essential loads 22 that normally get on, to bring it considerably above 23
- he 70%. )
24 In fact, pre- the situation I'm told that in the 25 Grand Gulf situation is actually up in the order of l
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90%. For this exercise, on these diesels, with the 2
corrected situation, we are, I believe, by this tech 3
spec amendment, dropping that testing limit to a lower 4
level such that we don't overstress the diesel.
MR. DENTON: This has been the subject of a lot of 6
discussion between the industry and ourselves, because 7 ~
obviously if you don't push it toward its nameplate's 8
rating, the survival and the stresses are much lower 9
than you'd get from running it high.
10 So I think that whole area is under examination, and in fact, we have recently concluded w'e should relax 12 some of our requirements for fast start, full load
'3 test, because of that same sort of consideration that 14 we were perhaps wearing them out rather than gaining 15 the confidence of them.
16 MR. DIRCKS: I think generically we are taking a 17 look at all of our testing requirements. We're 18 beginning to take a look.
We do have a lot of testing requirements not only 20 in diesels, but across the board. We do have tests 21 required, that people are beginning to wonder whether 22 we might not be reducing safety margins by this 23 constant testing procedure we go through.
24 M R. DENTON: If you'd like, we could come back and 25 talk further about that issue. We don't have a final PREE STATE REPORTING INC. j Cown aeserting . Depeestions '
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' resolution of it, but it is an important issue.
2
,ge,re looking at it across the board, and will 3
probably be resolved in the course of our completing 4
this overall diesel review.
5 COMMISSIONER ASSELSTINE: I think that would be 6
useful at some point.
7 CHAIRMAN PALLADINO: All right. Maybe that's 8
enough on that for the moment, unless you have more.
8 Okay.
10 M R. EISENHUT: If I could go to the next slide. .
" I'm sorry, this is on shift advisors. This flows from 12 a previous Commission discussion and meetings >n the
'3 lack of. hot operating experience on shif t at a number of plants.
15 Recall that on Diablo Canyon, we had a review there 16 of the industry group going in, reviewing the shift
'7 advisor program, and the staf f went in and also did a 18 review.
18 The situation here is pretty much the same in the 20 sense that the industry gc in in A,pril, 1984 I 21 believe it was the same head of the teaat that was used 22 at Diablo Canyon.
23 They reviewed all aspects of the shif t areas, 24 interfaces, between the shift and the advisors, the 25 procedures, w_
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107 comment that if, in fact, you weren't informed that you 2
would be expected to present statements here today, at least you should get credit, then, for being prepared 4
- for an unanticipated event.
5 (Laughter.)
8 CHAIRMAN PALLADINO: Now is the Commission prepared 7
to consider voting? All right. I propose to poll each a commissioner so that each one of you has the opportunity to make whatever statement you'd like to 10 make with regard to your vote.
" I thought I'd start of f. I cast my vote to 12 authorize the issuance of f'ull power op'erating license
'3 for Grand Gulf Unit 1 nuclear power plant because after
'd a careful examination of the issues, I am convinced 15 that the plant can operate safely ar.d in accordance Mi with NRC's regulations.
'7 Although this plant hirs't licensed to operate up to is 5% in June 1982, it has' experienced a number of "I
problems.
20 I believe that these problems have been resolved.
21 The NRC staff has advised the Commission that all 22 remaining full power issues have been satisfactorily 23 addressed by the utility, specifically operators have 24 completed a recertification program and have pass d NRC l
25 tests. l s
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108
' The technical specifications is corrected, have 2
been determined by the NRC staff to provide assurance 3
that the plant can be operated safely.
Additionally, the NRC staff has determined that the 5
emergency on-site diesel generators are reliable to 6
perform their intended function if needed.
7 Particularly relevant to MP&L's successful 8 resolution of identified problems have been their efforts to upgrade management capability.
10 Since the discovery of the problems at Grand Gulf,
' the utility has' made a number of significant management 12 and personnel changes and these changes have been made
'3 at levels including the plant manager, the president of MP&L, the senior vice president, the nuclear
'5 operations supervisor of training, and special 16 corporate consultants.
'7 Lastly, I would note my firm belief that the
'8 regulatory licensing process has worked in this case.
Many of the plant's problems were identified during 20 the shakedown period associated with low power testing.
21 Such problem identification is a fundamental reason 22 for carrying out such testing.
23 Now, in my view, Grand Gulf's problems have been 24 resolved by the utility and confirmed by the NRC staff 25 peyiew, l
l FREE STATE iIPORTING INC. l Cowt Reporting e Depeettiens 1 D.C. Aree 141-1901 e Belt. 46 Annep.149-4134 l 1
_. 109 My vote today underscores my studied determination 2
that the plant can operate safely at full power.
3 Now let me turn to Commissioner Roberts.
COMMISSIONER ROBERTS: I would acceht the 5
recommendation of the regional administrator of the 6
director of licensing, the director of nuclear reactor 7
regulation, that this plant is safe and I would let it 8 begin power ascension leading to full power and 9
commercial operation.
10 And good luck in your endeavor.
11 CHAIRMAN PALLADING: Comissioner Asselstine?
12 COMMISSIONER ASSELSTINE: I think that, as Mr.
13 Cavenaw said, this utility has had a rough time in its 14 low power program.
15 I think there are lessons that all of us can learn 16 from that. We didn't do as well as we should, they 17 didn't do as well as they should during the low power 18 program. -
19 We ought to be more careful in the future to make 20 sure that these kinds of problems don't reoccur.
21 I have to say that there has been, in my view, a 22 strong response to those problems, key to the principle 23 weakness that was involved, weakness in management of 24 the company.
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' and over the past week or so in my visit to the plant, 2 have been made in that the progress and improvements 3
restructuring the organization, changing the attitudes .
and commitments to safety on the part of the utility, 5 and generally, I'm satisfied with what I heard today 6
and with the staff's recommendation.
7 There is one problem I have, and that's a problem 8 that was not created by the utility or the staff, but 9 by my colleagues on the Comtnission.
10 Last week, the Commission decided that it was M going to change the position that it bad outlined in 12 the Shoreham decision just about a month or so'ago on 13 what would be required in terms of issuing exemptions from our regulations'for new license applicants.
15 I disagreed with that chani,e b; the Commission. I 16 think that the standard that's set forth in Shoreham is 17 the right standard.
38 I don't see any reason for differentiating between 19 Shoreham and this or any other new plant that's 20 applying for a license.
21 Unfortunately, the staff hasn't completed its 22 review of those exemption requests, and therefore I'm 23 going to abstain from the vote today on this license 24 issuance.
25 I want to see what the staff has to say in terms of PRIE STATI REPORTING INC.
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' whether the exemption requests for this plant meet the 2
kind of rigorous safety test that I think ought to be 3
applied in all of these cases. -
So until that wofk is done, I'm going to abstain, 5 although I have to say that in the other areas that we 6
have discussed today, I'm generally satisfied with the 7
changes that have been made and the improvements that 8 have been taken by the utility and in their general 9
readiness to operate the plant.
10 CHAIRMAN PALLADINO: Commissioner Bernthal?
11 COMMISSIOf:ER BERNTHAL: I hesitate to use the term
~
12 lessons learned from an experience here, because that 13 has come to be a rather chilling phrase since it's so 14 often been used in other contexts.
15 Eut I think that everybody in this case has I earned 16 some valuable lessons in the case of the Grand Gulf 17 experience.
18 The NRC has learned some lessons of its own.
19 Certainly the utility has evidenced in part by the 20 significant and important management changes they've 21 made over the recent past, learned a number of lessons 22 the hard way, I might add.
23 I think the AE itself and the vendar probably 24 learned some lessons from the advent of this new 25 generation plant.
1 1
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. 112 Whatever the difficulties cf the past, we're 2
required to deal today with what the currer.t situation 3
is and in my judgment, today, Mississippi Foxer & Light 4
is the utility and this plant has the first of a next 5
generation SWR prepared for operation, and I'm prepared 6
to cast my vote in favor of that operation today.
7 CHAIRMAtl PALLADINO: You do so?
8 COMMISSIONER BERNTHAL: I do so.
9 CHAIRFA!! PALLADING: Commissioner Zech?
'O COMMISSICNER ZECH: I had had a chance to review
" the history and the problems of Grand Gulf. I must 12 a d m i t I w o u l d h a v e l i k e d t'o h a v' e h a d rio r e t im e t o d o 13 that.
14 But I have given it, I believe, considerable 15 attention. I bev e visited the plant, and talked to 16 the senior car.agen.ent, talked to the operators, looked
'7 at the plant from many d'ifferent angles.
18 I have given considerable thought to the possibility of voting for full power operations. In my 20 view, Grand Gulf is ready for full power operations, 21 and I so vote.
22 CHAIRMAN PALLADINO: This is the result that you've 23 all heard is four in favor, authorizing the staff to j 24 permit full power ascension up to full power, and one 25 abstention.
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. 114
' CERTIFICATE Q,E PROCEEDINGS-2 3
This is to certify that the attached proceedi.ngs before the NRC CottMISSION 5
In the matter of:
6 DISCUSSION AND VOTE ON FULL POWER CPERATING LICEIISE 7
FOR GRAND GULF a Date of Proceeding: July 31, 1984 9 Place of Proceeding: Washington, D.C.
10 were held as herein appears, and'that this is the
" original transcript for the file of the Commission.
12 13 MELBA REEDE?
14 Cfficial Re:orter 15 16 , .
N L'.L Cd Lv. .L; ; [,,t[j-
'7 Official Reporter '- Signature 18 19 20 21 22 23 <
l 1
24 25 FREE STATI REPORTING INC.
Casset Reporting
- Depositions D.C. Aree 141-1901 e Belt.& Annep. 149-4134
a c h 2 N j l4 f'/- - Attachmnt 2 8 -
, SAFETY EVALUATION REPORT GRAND GULF NUCLEAR STATION UNIT 1 RELIABILITY OF DIESEL GENERATORS MANUFACTURED BY TRANSAMERICA DELAVAL, INC.
TDI PROJECT GROUP DIVISION OF LICENSING
1.0 INTRODUCTION
In support of its request for a full power license for Grand Gulf Nuclear Station (GGNS) Unit 1 and in response to an NRC Order dated May 22, 1984, Mississippi Power and Light Company (the licensee) submitted by letter dated July 5, 1984, a description of the June 1984 disassembly and inspection of the Division I diesel generator; the post-inspection engine test program; and proposed enhancements to the licensee's maintenance and surveillance program.
As required by the NRC Order, the licensee submittal also addresses the similarity of the "as-manufactured quality" of the Division I and II diesel generators as part of the licensee's justification for not inspecting the Division II engine.
(
2.0 BACKGROUND
Concerns regarding the reliability of large bore, medium speed diesel generators of the type supplied by TDI at GGNS Unit 1 and at fifteen (15) other dcmestic nuclear plants were first prompted by a crankshaf t failure at Shoreham in August 1983. However, a broad pattern of deficiencies in critical engine components have since beccme evident at Shoreham, Grand Gulf Unit j and at other nuclear and non-nuclear facilities employing TDI diesel generators.
These deficiencies stem frcm inadequacies in design, manufacture and QA/QC by TDI.
In response to these problems, thirteen U.S. nuclear utility cwners, including the licensee, formed a TDI Diesel Generator Owners Group to address operational and regulatory issues relative to diesel generator sets used for standby emergency pcwer. The Owners Group program, which was initiated in October 1983, embodies three major efforts.
- 1. Resolution of 16 known generic problem areas (Phase I program) intended by the Owners Group to serve as an interim basis for the licensing of plants.
- 2. Design review of important engine cceponents and. quality revalidation of >
important attributes for selected engine components (Phase II program).
- 3. Identificatien of any needed additional engine testing or inspections, based on findings stemming from the Phase I and II programs.
u
a v
.w Pending _comple+. ion of the Owners Grcup program, the licensee submitted a number of reports concerning its actions to ensure the reliability of the TDI diesels at GGNS Unit 1. Based on its review of these reports and the status of the Owners Group. program, the staff-stated in its Safety Evaluation-Report issued in support of the May 22, 1984 Order that additional informatien was needed regarding the present condition of critical engine components to support operation of GGNS Unit I at power levels in excess of 5% of full power for the interim period pending completion of the Owners Group program and NRC staff raview of recommendations stemming from this program as they apply to GGNS Unit 1. In addition tq the engine inspections and subsequent post-inspection engine tests required by the Order, the staff's SER stated it would be necessary to review the licensee's proposed engine maintenance and surveil-lance program and any needed license conditions prior to issuance of a full pcwer license.
3.0 EVALUATION Enclosure 1 to this SER is a Technical Evaluation Report (TER) entitled
- " Review and Evaluation of Transamerica Delaval, Inc. Diesel Engine Reliability 1
and Operability - Grand Gulf Nuclear Station, Unit 1." This TER was prepared by Pacific Northwest Laboratory (PNL) which is under contract to the NRC to
' perform technical evaluations of the TDI Owners Group's generic program, in addition to plant-specific evaluations relating to the reliability of TDI
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diesels. PNL has retained the services of several expert diesel consultants as part of its review staff.
In addition to the July 5,1984 submittal, PNL and its consultants also reviewed the licensee submittals dated February 20, April 17, and May 6,1984, and performed an onsite inspection of key engine components in June 1984, while the Division I engine was disassembled. PNL and its consultants also considered the status of the generic Owners Group program relative to the l actions taken by the licensee to establish the reliability of the diesels.
The staff has reviewed the enclosed TER, and adopts the TER as part of this Safety Evaluation by reference.
3.1 Division I Engine The June 84 inspection of key engine components, including those identified by the Owners Group as known potential problem areas, indicates that these components are acceptable for nuclear service for the interim period extending to the first refueling of GGNS Unit 1. This finding is subject to (1) operating restrictions as identified in Section 3.4 of this SER, and (2) conpleticn of licensee actions pertaining to confirmatory issues as identified in Section 3.5 of this SER.
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,f . Post-inspection testing, as required by the May 22, 1984 Order, was satisfactorily completed. The licensees letter dated July 2, 1984, provided the' licensees clarifications / interpretations of the required testing.
Although the fast start tests of the engine.in accordance with the Order were performed subsequent to a manual prelubing of the turbocharger thrust bearings and thus did not simulate the worst challenge to the bearings, PNL does not recomend additional testing to simulate this challenge. The NRC staff concurs with this PNL finding and concludes that the tests performed by the licensee meets the intent of the NRC Order.
3.2 Division II Engine i In the Order dated May 22, 1984, the NRC staff stated that the need for Division II engine inspection would be contingent upon:
- 1. Results of the inspection of the Division I engine a 2. The licensee's ability to demonstrate, through a review of the manufacturers QA records, that the two engines are of similar "as manufactured" quality.
The Division I engine inspection revealed only one component, the turbocharger, where failed elements, bolts and a vane, might be expected to'accur in the Division II engine. The other components showed no rejectable indications or incipient problems that suggested adverse conditions might be present in the Division II engine.
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Accordingly, PNL concluded that the turbochargers from the Division II engine should be inspected and any corrective actions taken and findings documented.
No other Division II inspections were recomended on the basis of the Division I results.
In its submittal dated July 20, 1984, the licensee reported that the Division II turbochargers have been inspected for the type of damage found in the Division I turbochargers. The scope of the inspection included the stationary nozzle ring, vanes, bolts, and rotating turbine blades. The Division II turbochargers showed no signs of rotating disk damage, although one vane was found to be missing frem each stationary nozzle ring (a similar condition was observed in the Division I turbochargers ~see discussion in enclosed TER). The stationary nozzle ring bolts were found to be intact with no evidence of stress corrosion -
cracking. The licensee elected to replace the nozzle ring assembly and bolts although the old parts were judged to be acceptable. Turbine rotor float measurements were also performed and indicated no significant thrust bearing wear. Based upon its review of the licensee's July 20, 1984 submittal, the NRC staff concludes that the licensee has satisfactorily addressed PNL's concern with respect to the Division II turbocharger.
On the basis of the review conducted by the licensee on the manufacturer's QA records and the upgrades accomplished for both engines, PNL concludes that the Division I and II engine components are of comparable "as-manufactured" quality. On the basis of their operating history, PNL concludes that the
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,s 4 engines have been assembled and maintained comparably. Moreover, PNL has noted l that the Division II engine has seen less service than the Division I engine. l In addition, based upon the status of its review of the Owners Group proposed generic resolution of the connecting rod issue, PNL has concluded that visual inspections of the connecting rods and a preload check of the connecting rod bolts should be performed on the Division II engine prior to plant operation above 5% power. The license has comitted to per-forming this inspection in its submittal dated July 20, 1984 Based on these factors and the absence of significant adverse findings from the recent inspection of Division I engine, the staff has concluded that. no further inspections of the Division II engine beyond those identified above are necessary at this time.
3.3 Aucmented Maintenance and Surveillance Program PNL concluded in the enclosed TER that modifications to the Augmented Maintenance / Surveillance Program proposed by the licensee in their July 5, 1984 submittal are needed to provide adequate assurance of engine reliability /
operability. These modifications are discussed in detail in Section 6 of the enclosed TER.
By letters dated July 20, and July 23, 1984, the licensee comitted to a revised Augmented Maintenance and Surveillance Program. The NRC staff has reviewed these letters and concludes that the MP&L program incorporates all of the
( modifications recomended by PNL. Therefore, the staff finds the Augmented Maintenance and Surveillance Program, as identified in the licensee's July 20, and July 23, 1984 letters, to be acceptable.
3.4 Operating Restrictions PNL recomendations and conclusions regarding TDI diesel engir.e reliability at GGNS Unit I are predicated on the following assumptions:
- 1. The emergency service requirements the licensee currently forsees for GGNS Unit I will not exceed the engine. load corresponding to a break mean effective pressure (BMEP) of 185 psig. The need for this assumption is based on PNL concerns regarding the acceptability of crankshaft stresses at higher BMEP loadings.
- 2. All future engine testing (except the torsfograph test and the test to obtain preturbine exhaust temperature data as described in the next Section) including surveillance testing required by the plant Technical Specifications will be limited to within : 5% of the nominal engine load where the upper limit of this load range corresponds to a BMEP of 185
'psig.
- 3. In the absence of the Owners Group completing all elements of their program plan, PNL's conclusions are plant-specific, applying only to GGNS Unit 1 and are applicable only during its first reactor refueling cycle. It is understood by PNL that at the first refueling, the licer.see
( will implement all applicable recomendations of the Owners Group.
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,- - i With regard to item 1 above, the licensee reported by letter dated July 20,
- 1984, (AECM-84/0376) that 185 psig BMEP corresponds to a generator load of 5740KW, about 82% of full rated load. This exceeds the maximum ESF loads, 52% and 68% of full rated load for the Division I and II engines, respectively, required to shutdown the plant and maintain it in a safe condition for loss 4
of.offsite power and LOCA. Thus, there exists sufficient engine capacity-at 185 psig BMEP to assure that the> fuel design limits and design conditions of the reactor coolant system boundary are not exceeded, and that the core -
is cooled and containment integrity and other vital functions are maintained in the event of postulated accidents as required by GDC-17.
The licensee also states in a letter dated July 20, 1984, (AECM 08/0373) that a precautionary note will be added to the GGNS Off-Normal Event Procedure for Loss of Offsite Power to ensure that loads will not be added unnecessarily to the engines in excess of 185 psig BMEP (5740 KW).
In addition, future training with respect to this procedure will explain 4 both the basis for the note and the aspects to be taken into consideration in its application. The staff agrees in principle with these precautions; however, the staff is adding a condition to the license (See Appendix A
" License Conditions") to require that these actions be completed prior to plant operation above 5% power M . The NRC will verify that
. these actions have been completed.
( With regard to item 2 above, the licensee has submitted proposed Technical Specification changes incorporating this item. Specifically, the proposed changes would require that the monthly and 18 month surveillance tests be performed at a minimum of 5450 KW (70% of rated load), but not to exceed 5740 KW (82% of rated load,185 psig BMEP). The lower limit is greater than the auto-connected loads required for the loss of offsite power and post-LOCA conditions as described above. Therefore, the staff finds these changes to be j acceptable.
With regard to item 3, the full power license is being conditioned to require NRC review and approval of licensee actions pertaining to a final resolution
.l of the TDI diesel generator issues at GGNS Unit 1 (See Appendix A).
3.5 Additional License Conditions By letter dated July 17, 1984, the staff identified additional information requested by the staff. The specific information requested was identified R under item 0 in the July 17, 1984 letter and includes those informational l items (referred to as " additional MP&L submittals") identified in Section S '
of the enclosed TER. I I
By letter dated July 20, 1984, AECM-84/0373, the license provided satisfactory responses to all but 3 items. These items for which satisfactory responses were not received include the following:
- 1) crankshaft torsiograph data at 0%, 25". 50%, 75%, and 100% of engine s nameplate loading were not submitted. This information is needed (1)
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to confirm adequate crankshaft torsional responses over the spectrum of engine loads to be seen in service, and (2) to provide relevant data.to assist the staff and PNL in completing its generic evaluation of the adequacy of the DSRV-16-4 crankshaft design.
- 2) Preturbine exhaust temperature data at 0%, 25%, 50%, 75%, and 100% of engine nameplate loading was not submitted. This data was requested as a result of a review of cylinder exhaust temperature data obtained from the engine operating logs when the PNL diesel engine expert consultants visited the , site on June 4 and 5, 1984. This information is needed to confirin that the even hotter turbine inlet temperatures do not exceed the manufacturers recommendations.
- 3) Informat:icn~provided regarding the corrective actions taken in response to numerous fuel oil line leaks during the period of September to November 1983 has not convinced the NRC staff these actions are sufficient to prevent further occurrences of this kind. Apart from the
- major leak which occurred on September 4,1983, causing a fire and for which the staff agrees the. licensee has taken sufficient action (See attached TER), the other several occurrences involved minor damage to tubes from external causes, particularly from damage caused by maintenance operations. Clearly, periodic inspection of the fuel lines is a major element to preventing reoccurrences.
Although the torsiograph test is a requirement of the May 22, 1984 Order, it is the staff's understanding that the test has not yet been completed. Under the Order, the licensee must complete this test prior to operating the plant above 5% power.
The staff concludes that the above torsiograph and preturbine exhaust temperature data is primarily of a confirmatory nature and is therefore not likely to change the conclusions of this SER. For this reason the staff concludes that plant operation in excess of 5% power should not be conditioned upon staff 4
review and approval of this information. However, this data should be submitted to the NRC prior to plant operation above 5% power as a ccndition of the license (See Appendix A).
1 Regarding the fuel oil lines, the staff concludes that the licensee should perform, as a condition of the license (See Appendix A), an inspection of all fuel lines in the Division I and II engines for external damage, and replace or repair all defective lines. These inspections may include inspections already completed provided they were performed subsequent.to relevant engine i
reassembly operations associated with the inspection of the Division I diesel generator and of the Division II turbochargers in June and July 1984 The NRC will verify that these actions have been ecmpleted. The licensee should also submit a proposed periodic surveillance program for the fuel oil lines.
These actions shall be completed prior to plant operation above 5% power.
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. 4.0 Conclusions The NRC staff concludes that the TDI diesel engines at GGNS Unit I will provide a reliable standby source of onsite power in accordance with General Design Criterion 17. This finding is based upon the.NRC staff /PNL review of (1) the current status of the TDI Owners Group Program in resolving the TDI diesel engine issue; (2) actions taken by the licensee.to enhance and verify the reliability of the Division I and II engines, including those actions taken in response to the NRC order dated May 22,1984;(3) the Augmented Engine Maintenance and Surveillanca Program which the licensee committed to by letters dated July 20 and 22,1984; and (4) changes to.the Technical Specifications to limit future testing of the engines to 185 BMEP. In addition, this finding is subject to the license conditions identified in Appendix A, which assure that Grand Gulf Unit I will continue to meet GDC 17 beyond the first refueling outage.
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Appendix A License Conditions Pertaining to - - :
the Division I and II Diesel Generators at Grand Gulf Nuclear Station, Unit 1
- 1. The licensee shall submit the following information prior to operation of GGNS Unit 1 at a power level exceeding 5% of full power, a) Torsiograph data for the Division I diesel generator at 0%, 25%,
50%, 75%, and 100% of full engine rated load, and associated stresses.
b) Preturbine exhaust' temperature data for the Division I and II diesel generators at 0%, 25%, 50%, 75%, and 100% of full engine load. Maximum values for this data as recommended by the turbocharger manufacturer shall also be provided.
- 2. The licensee shall complete the following' actions prior to GGNS Unit 1 operation above 5% of full power.
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a) A precautionary note shall be added to the GGNS Off-Normal Event Procedure for Loss of Offsite Power to ensure that loads will not be added unnecessarily to the Division I and II engines in excess of 5740 KW. Operators shall be trained with regard to the basis for the note and the factors to be taken into consideration regarding its application.
b) All fuel-oil lines (including injector lines) shall be visually inspected in the Division I and II diesel generator for external damage, and defective lines repaired or replaced. The inspections may include inspections already completed provided they were performed subsequent to relevant engine reassembly operations associated with the inspections of the Division I diesel generator and of the Division II turbochargers in June and July, 1984. The licenses shall also submit a proposed periodic surveillance program for the fuel-oil lines.
- 3. Final evaluations and recommendations from the TDI Owners Group Program applicable to GGNS Unit 1, and the licensees actions in response to this prcgram for the Division I and II diesel generators shall be submitted for NRC review and approval prior to plant restart from the
- first refueling outage.
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PNL-5201 Review and Evaluation
- of TransameriCa Delaval, InC.,
Diesel Engine Reliability and Operability - Grand Gulf Nuclear Station Unit 1 July 1984 Prepared for the U.S. Nuclear Regulatory Commission under Contract DE-AC06-76RLO 1830 NRC FIN B2963 Pacific Northwest Laboratory Operated for the U.S. Department of Energy by Battelle Memorial Institute J % n ~ .,. , $2 V,yJ CC'dC:.C 2
l PNL-5201
. REVIEW AND EVALUATION OF TRANSAMERICA DELAVAL, INC.,
. DIESEL ENGINE RELIABILITY AND OPERABILITY - GRAND GULF NUCLEAR STATION UNIT 1 July 1984 ,
Prepared for Division of Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission under Contract DE-ACD6-76RLO 1830 NRC FIN B2963 Project
Title:
Assessment of Diesel Engine Reliability / Operability
.. NRC Lead Engineer: C. H. Berlinger Pacific Northwest Laboratory Richland, Washington 99352 ;
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. . *l PACIFIC NORTHWEST LABORATORY PROJECT APPROVALS ek -.
i s a Date N'w w lo, / VN W. W. Laity, Project Manager [
.. Pacific Northwest Laboratory Date 7'D'65 W. D. Richmond, Chairman Senior Review Panel Pacific Northwest Laboratory l
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CONTENTS 1.0 ' INTRODUCTION......................................................... 1
.2.0 BACXGROUN0........................................................... 3 2.1 0WNERS ' GROU P PR OGk AM PLAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2 GRAND GULF NUCLEAR STATI0N...................................... 4 3.0 EVALUATION OF MP&L DIVISION I ENGINE DISASSEMBLY AND INSPECTION...... 6 3.1 GENERIC PR0BLEMS................................................
7 3.2 PLAN T-SPEC I F IC PR0BLEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
. 4.0 ANALYSIS OF THE REQUIREMENT FOR DIVISION II ENGINE INSPECTION........ 3a 4.1 OIVISION I ENGINE INSPECTION RESULTS............................ 34 4.1.1 PNL Evaluation........................................... 34 4.1.2 PNL Conclusions.......................................... 24 4.2 ENGINE SIMILARITY DEMONSTRATION................................. 34 4.2.1 PNL Evaluation..................................'......... 35 4.2.2 PNL Conclusions.......................................... 35 5.0 REVIEW 0F THE POST-INSPECTION TESTING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 5.1 PNL EVALUATION.................................................. 37 5.2 PNL CONCLUSIONS................................................. 37 6.0 REVIEW 0F THE PROPOSED AUGMENTED MAINTENANCE / SURVEILLANCE PROGRAM.... 39 i 6.1 PNL EVALUATION.................................................. 39
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f 6.1.1 Cylinder Heads........................................... 41 6.1.2 Connecting Rods.......................................... 41 6.1.3 Lube Oil Checks.......................................... 41 6.1.4 Studs / Fixtures........................................... 42 i
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6.1.5 Pu s h Ro ds , Ca ms , E t c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 6.1.6 Additional Surveillance.................................. .
42 6.2 PNL CONCLUSIONS................................................. 43 7.0 OVERALL CONCLUSIONS.................................................. 45 7.1 LIMITED ENGINE REQUIREMENTS..................................... 45 7.2 NRC CONCURRENCE WITH ADDITIONAL MP&L SUBMITTALS................. 45 7.3 ENGINE BMEP LIMITAT,10NS......................................... 46 7.4 REVISED SURVEILLANCE / MAINTENANCE PR0 GRAM........................ 46 9
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. 4 REVIEW AND EVALUATION OF TRANSAMERICA DELAVAL, INC., DIESEL ENGINE s RELIABILITY AND OPERABILITY - GRAND GULF NUCLEAR STATION UNIT 1
1.0 INTRODUCTION
In support of its request for a full power license of Grand Gulf Nuclear
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Station (GGNS) Unit 1 and in response to an NRC Order dated May 22, 1984, Mississippi Power & Lignt Company (MP&L) submitted a report on July 5,1984, addressing three areas:
e a description of the June 1984 Hsassembly and inspection of the
, Division I diesel generator e the post-inspection engine test program o pruposed enhancements to the MP&L maintenance and surveillance pro gram.
- As also required by the NRC Order, the MP&L submittal addresses the similarity of the "as-manufactured quality" of the Division I and II diesel generators as part of MP&L's justification for not inspecting the Division II engine. Thes e diesel generators are Model DSRV-16-4 manufactured by Transamerica Delaval, Inc. (TDI) .
This Technical Evaluation Report (TER) documents Pacific Northwest Laboratory's (PNL) evaluation of the reliability and operability of the Division I and II diesel generators at GGNS Unit 1. In addition to the July 5, 1984 submittal, PNL has reviewed MP&L submittals dated February 20, April 17, and May 6, 1984 Other information, identified herein, was also considered as needed to support conclusions.
The TER organization is as follows: Section 2 provides oackground on the TDI problem resolution by both the group of nuclear utility TDI owners and MP&L. Section 3 provides a detailed review and evaluation of the Division I engine disassembly and inspection. Section 4 reviews the MPSL report on the comparability of the Division I snd Division II engines. Sections 5 and 6 document PNL's review / evaluation of MP&L's post-inspection engine tests and the l
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utility's proposed augmented maintenance / surveillance program, respectively.
Finally, Section 7 presents PNL's overall conclusions and recommendations regarding the two engines' suitability to serve as standby power sources at the
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GGNS.
1 Thi TER was prepared by the following PNL staff and consultants: i e D. A. Dingee, PNL project staff e A. J. Henriksen, diesel consultant to PNL e J. E. Horner, representing Seaworthy Systems, Inc., diesel consultants to PNL ,
o P. J. L:ezecky, Engineered Applications Corporation, diesel consultant to PNL.
Others whose contributions were considered in formulating the conclusions include PNL Assesment of Diesel Engine Reliability / Operability Project Team memoers J. M. Alzheimer, M. Clement, S. D. Dahlgren, R. E. Dodge, W. W. Laity, J. F. Nesbitt, J. C. Spanner, and F. R. Zaloudek; and consultants S. H. Bush, B. J. Kirkwood (Covenant Engineering), and J. A. Webber (representing Ricardo Engineering).
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4 2.0 BACXGROUND 2.1 OWNERS' GROUP PROGRAM-PLAN-Thirteen nuclear utilities that own diesel generators manufactured by Transamerica Delaval, Inc. -(TOI), have established an Owners' Group to address
. questions raised by a major failure in one TOI diesel (at the Shoreham Nuclear Power Station in August 1983), and other problems .in TOI diesels reported in
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the nuclear 'and non-nuclear industry. On March 2,1984, the Owners ' Group submitted a plan to the U.S. N,uclear Regulatory Commission (NRC) cutlining a comprehensive program including 1) an in-depth assessment of 16 known engine problems (Phase I), 2) a design review and quality revalidation program that addresses other key engine components (Phase II), and 3) engine tests and inspections. A review of that submittal was conducted by PNL and reported to NRC in PNL-5161 dated June 1984.
Section 4 of PNL-5161 deals with considerations for interim licensing of nuclear stations prior to completion of the implementation of the Owner's Group Program Plan. Recommendations relevant to MP&L licensing of the GGNS at this .
time are:
e The engine should have AE pistons or complete " lead-engine" tests as described in Section 2.3.2 of PNL-5161.
e The diesel generator should not be required to carry a load in excess of that corresponding to engine Brake Mean Effective Pressure (BMEP) of 185 psig.
- The engine should be inspected per Section 2.3.2.1 of PNL-5161 to confirm that the components are sound.
- Pre-operational testing should be performed as discussed in Section 2.3.2 of PNL-5161.
e The engines should receive enhanced surveillance and maintenance.
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2.2 GRANO GULE NUCLEAR STATION dn MP&L submittal to NRC, dated February 20, 1984, provided a review
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of the resulis of their program of inspection, upgrading, testing and i maintenance. The PNL r'eview of this document was provided to NRC in a letter dated
- March 30, 1984 A number of concerns were. identified by PNL, m , 3 namely: -
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. e The MP&L report di[not provide sufficient information to convince the reviewers that-the AE pistons were suitable for GGNS licensing.
e The_ evidence was insufficient to conclude that the cylinder heads wculd perform reliably.
e The connecting rod bearings were not demonstrated to be suitable for operation at GGNS.
e The push rods were not adequately tested.
e Data concerning crankshaft deflections and main bearing wear were needed to confirm the adequacy of the crankshaft.
- t. e The high-pressure fuel line needed'to be examined to assure the reviewers that the new lines installed at GGNS are not defective.
e MP&L did not adequately consider the possibility of cracks in the cylinder block.
e Additional information was needed to confirm that the engine base would not crack.
e MP&L did not address head stud problems noted by the Owners' Group.
. e The issues on rocker arm capscrews were not closed out per the Owners ' Group recommendations.
e The PNL reviewers needed more information from MP&L on turbocharger mounting.
e lhe evidence provided by MP&L on the connecting rods was insufficient to conclude that they would be adequate.
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e MP&L did not address the potential for wrist pin bushing failures; PNL noted that. cracks had been observed in wrist pin bushings at the Shorenam Nuclear Power Station.
e The test program was deemed to be inadequate.
e The description of the surveillance and maintenance program was insufficient for the PNL reviewers to draw conclusions.
This detailed PNL review of the February 20 MP&L submittal was followed by a letter dated April 16, 1984, in which PNL recommended a number of actions to support licensing of the GGNS. These included 1) inspection of one engine at GGNS, 2) post-inspection testing, and 3) maintenance and surveillance items.
In a letter dated April 17, 1984, PNL provided additional clarification on
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these actions.
On April 25, 1984, NRC issued a letter to MP&L identifying these actions as an acceptable basis to support full power operation at GGNS for one fuel cycle pending completion of the Owners' Group Program Plan.
After considering additional, updated information provided by MP&L by letter dated May 6,1984, NRC issued an Order dated May 22, 1984, requiring disassemoly and inspection of one engine before the power ascension program could be authorized. Comments pertaining to the need for these inspections were provided in a PNL letter dated May 21, 1984 On June 4 and 5,1984, PNL staff and consultants visited MP&L to review the Division I engine components. A PNL letter dated July 9,1984, summarized the results of this inspection. In general, the inspection did not reveal any problems that should seriously impact the reliability and operability of the
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engine for the first reactor fuel cycle, i
On July 5,1984, MP&L provided NRC with a report on the Division I disassembly and inspection, in response to the May 22, 1984, Order. This report also compared the Division II diesel generator (DG) to the Division I OG, and addressed post-inspection testing and a proposed augmented maintenance
, and surveillance program aimed at assuring the future satisfactory performance of botn engines. .This submittal was the topic of discussion at a meeting held July 13, 1984, among representatives of MP&L, NRC, and PNL.
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. 3.0 EVALUATION OF MP&L DIVISION'I ENGINE DISASSEMBLY AND INSPECTION
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. In compliance with the NRC Order of May 22, 1984, MP&L disassembled the Division I TOI engine and inspected all critical components. These components included those that are being addressed as part of the Owners' Group P'1ase I Program regarding known generic problem areas: cylinder hea'ds, engine block and base, connecting rods, pistons, studs, cap screws, push rods, etc. The specific inspection methods used were identified in the NRC Order. Actions taken by MP&L in conducting the disassembly and inspection are consistent with Section 2.3.2.1 of PNL-5161 dealing with pretest inspections.
This section documents PNL's technical evaluation of MP&L's resolution of each of the 16 known generic problems (components) as well as 8 problems specific to GGNS. It consists of worksheets providing 1) component identification, 2) a brief history of failures, 3) the status of the Owners' Group Program aimed at resolving the problem, 4) the status of MP&L in resolving the problem, and 5) PNL comments / conclusions. PNL's conclusions and comments are based not only on the MP&L submittal of July 5,1984, and the related discussions on July 13, 1984, but also on an onsite inspection of the engine components. It must be emphasized that, pending completion of the implementation of the Owners' Group Program Plan, PNL's conclusions are plant-specific, applying only to MP&L's Grand Gulf Nuclear Station Unit 1 and to operations only during its first reactor refueling cycle. It is understood that, at the first refueling, MP&L will implement all applicable recommendations of the Owners' Group.
The order of worksheet presentation is as follows. The 16 known problems are reviewed in the order listed in PNL-5161, Table 1. Next, the GGNS-specific problems are reviewed in the following order: low-presure fuel lines, crankcase cover capscrews, fuel oil leaks, air start valve failures, air start solenoid valve failure, fuel oil injection pump, cracks in air box, and failures to start Division I engine.
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3.1 GENERIC PROBLEMS Component: Piston Skirt Part No. 03-341-04-AE Owners' Group Report: FaAA-84-2-14 Brief History of Failures Based on a number of cracks found in AF piston skirts at GGNS, Shoreham, and at non-nuclear installatipns, the skirt design was strengthened in the boss area where the cracks had been found. No failures have been reported to date on the redesigned diston skirt, labeled AE, in either nuclear or non-nuclear installations. Kodisk.has operated in excess of 6000 hours0.0694 days <br />1.667 hours <br />0.00992 weeks <br />0.00228 months <br /> at approximately 185 BMEP (1200 psi maximum pressure); the TOI R-5 test engine in excess of 600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br /> with maximum pressures of 2000 psi.
Owners' Grouo Status The Owners' Group consultant, Failure. Analysis Associates (FaAA), has analyzed the AE piston skirt design and has concluded that the AE skirts may crack at 10% overload, but that cracks will not propagace to the point of failure.
MP&L Status After observing cracks in several skirts, all AF skirts on both Division I and II engines were replaced with AE skirts in January / February 1984 Subs e-quently, after 270 hours0.00313 days <br />0.075 hours <br />4.464286e-4 weeks <br />1.02735e-4 months <br /> of operation, all Division I skirts were inspected oy liquid penetrant and no rejectable indications were observed. However, tne piston skirt-to-crown surface on all skirts and crowns showed slignt signs of fretting due to relative movement.
PNL Conclusions PNL has reviewed both the Owners' Group report and the relevant inspection data. Based on this review, as well as on the aforementioned operating 7
4 experience with the Kodiak and R-5 engines, PNL concludes that the piston
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skirts are acceptable for operation up to and including 185 BMEP at 450 rpm -
(the 185 BMEP criterion is discussed in PNL-5161, Section 4, " Considerations for Interim Licensing").
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. c Component: Connecting Rod Bearing Shell l
Part No. 02 340-04-AG l Owners' Group Report: FaAA-84-31 Brief History of Failures No failures of the V-engine connecting rod (conrod) bearing shells have
. been reported in nuclear applications. However, a number of bearings have been replaced due to nonconformity with Owners' Group recommendations.
Owners ' Group Status Failure Analysis Associates has conducted both stress and orbital analyses of the conrad bearing shells. Provided the shells are dimensionally correct and otnerwise conform to specifications as recommended by the FaAA report, FaAA has concluded that the bearings are suitable for the service intended.
Mp1L Status In January / February 1984 all conrad bearings in both engines were replaced as a matter of ~ policy. In June 1984, after 270 hours0.00313 days <br />0.075 hours <br />4.464286e-4 weeks <br />1.02735e-4 months <br /> of operation, the Division I engine shells were inspected visually and by liquid penetrant. All bearings (except No. 7) were x-rayed. Bearing No. 7 was sent to FaAA to aid in the ongoing generic analysis. All other bearings were found acceptable in accordance with Owners' Group acceptance criteria. However, bearing No. 4 was replaced nonetheless, due to a 1/2-inch wide wipe caused by dirt. Bearing No. 7 was also replaced; all other bearings were reinstalled.
pNL Conclusions l PNL has reviewed the Owners' Group report and the relevant inspection data, and has visually inspected the bearings. PNL concludes that the bearings are acceptable for the first refueling cycle.
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. Component: Rocker Arm Capscrew Part No. 02-390-01-0G
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Owners' Group Report: Stone & Webster, March 1984 Brief History of Failures Rocker arm capscrew failures at Shoreham have been reported. There have
. been no. reports of similar failures elsewhere.
. Owners' Group Submittal .
Stone & Webster Engineering Corporation, a consultant to the Owners'
, Group, has performed stress analyses of both the original capscrew design (the type that failed at Shoreham) and a newer design. Stone & Webster has concluded that both designs are adequate for the service intended. Stone &
Webster has attributed Ole failure at Shoreham to undertorquing.
MPAL Status The rocker arm capscrews at GGNS are of the original design. These capscrews have experienced in excess of 107 loading cycles without reported failures. Breakaway torques measured during the June 1984 inspection were within acceptable limits. Torque was checked on all capscrews after reassembly in June 1984 PNL Conclusions Based on the analytical results and operating experience to date PNL
, concludes that adequate torquing ensures that the capscrews will provide acceptable service.
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Component: Air Start Valve Caoscrews Part No. Gb-032-114 ,
Owners ' Group Report: Stone & Webster, March 1984 Brief History of Failures No actual failures of capscrews have been reported. However, on May 13, 1984, TDI reported a potential defect due to the possibility of the 3/4-10 x 3-inch capscrews bottoming out in the holes in the cylinder heads, resulting in insufficient clamping o,f the air start valves.
Owners' Group Status Stone & Webster and TDI both have recommended that the 3-inch capscrews be either shortened by 1/4 inch or replaced with 2-3/4-inch capscrews.
MPSL Status Capscrews on both Division I and II OGs have been modified by shortening s
the 3-inen capscrews by 1/4 inch. Proper torque values were confirmed after reassembly.
PNL Conclusions After reviewing available reports and inspection data, PNL concludes that proper corrective measures were taken and that capscrews are acceptable for the first refueling cycle.
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Component: Push Rods Part No. 02-390-06-AB
. 0wners' Group Report: FaAA 84-3-17 Brief History of Failures The push rods originally had tubular steel bodies fitted with hardened steel end pieces attached with plug welds. Reportedly, an estimated 2".
developed cracks in or around the plug welds. A push rod design introduced
, later cor.sisted of a tubular steel body with a carbon steel ball fillet welded to each end. This design proved to be very prone to cracking at the weld. In all,15 of 16 rods on the GGNS Division I engine and 13 of 16 rods on the Division II engine were found to be cracked. All push rods on both Division I and Division II DGs have been replaced by a new design consisting of a tubular steel body with a steel cylinder friction-welded to each end. No failures are reported on this design.
Owners' Group Status Failure Analysis Associates has a performed stress analysis .as well as
] cycle wear test to 107 cycles on a sample of the friction-welded push rod at conditions simulating full engine nameplate loading. No sign of abnormal wear or deterioration of the welded joints was observed.
MP&L Status All push rods on both Division I and II engines were replaced in January / February 1984 by a new design consisting of a tubular steel body with a steel cylinder friction-welded to each end. During the June 1984 inspection, -
all push rods were inspected by liquid penetrant and no relevant indications were observed.
i PNL Conclusions j After reviewing the FaAA report and inspection data and noting the GGNS replacements, PNL concludes that the push rods incorporating the friction weld design are acceptable for the first refueling cycle.
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Component: Cylinder Head Stud Part No. 03-315-01-0A (Old Design)
Owners' Group Report: Stone & Webster, March 1984 Brief History of Failure To date, no failure of cylinder head studs has been reported in the nuclear industry. However, some isolated failures have been reported in the non-nuclear field. The cause has not been reported.
Owners' Grouo Status Stone & Webster Engineering Corporation has analyzed both the old design studs and the new necked down studs developed by TOI to minimize cylinder block cracking, and has concluded that both stud designs are adequate for the service intended, provided proper stud preload is applied.
MP&L Status The MP&L visual inspection revealed many instances of flat crests on the top threads of the studs and one instance of minor thread damage to the bottcm th reads . On the engine left bank cylinder No. 3, studs No. 4 and 5 had a 360*
discernable surface indication on the stud shank. None of the thread damage was considered service-related and it was concluded that the damage to stud No. 4 and 5 shanks was done during machining of the studs. These two studs were replaced by new studs. It is believed the replacement studs are of the new necked down design. This will be confirmed by MP&L. The damaged stud threads were chased with a die, re-examined, accepted, and reinstalled. Pre-load was checked on all studs after installation.
PNL Conclusions
, Based on a review of the Owners' Group report and the inspection data supplied in the July 5 submittal of MPSL, PNL concludes that the cylinder head studs are acceptable for the first refueling cycle.
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Component: High-Pressure Fuel Tubing Part No.: 03-365C Owners' Group Report: Stone & Webster, Aoril 1984 Brief History of Failures High-pressure (HP) fuel tubing developed leaks during preoperational testing on both the Shoreham and Grand Gulf engines. There are no other reported failures in nuclear applications.
Owners' Grouo Status Stone & Webster has analyzed the failed HP fuel tubing and has concluded tnat the failures originated in inner surface flaws that were initiated during fabrication. If, through eddy current inspection, the inner surface conoition of new tubing is found to be within specified conditions, the HP tubing is considered suitable for the service intended.
MP%L Status Fifteen HP fuel lines on both Division I and II engines are original equipment and have experienced over 10 million operating cycles. Operating stresses are therefore believed to be smaller tnan the hign-cycle fatigue endurance limit, and thus these tubes are believed to be free of detrimental defects to the inner surface. Both replacement tubes, one on each Division engine, have been subjected to the prescribed surveillance and were found to be sound.
PNL Conclusions PNL has determined that the original hign-pressure lines are acceptable.
7 based on their completing 10 operating cycles. PNL has also determined that the replacement tubes have been adequately inspected. Thus, PNL concluoes that the HP fuel tubing is acceptable for the first refueling cycle.
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Component: Crankshaft Part No. 02-310A Owners' Group Report: FaAA-84-4-16, (dated May 22, 1984)
Brief History of Failures Three V-16 crankshaft failures'have been reported, all in the non-nuclear industry. Two failures were attributed to torsional stress due to operation too close to the critical speed. No cause has been suggested for the third failure. ,
Owners' Group Status Failure Analysis Associates has performed torsional and bending stress analyses of the subject crankshaft and has concluded that the shaft will meet Diesel Engine Manufacturers Association (DEMA) standards at the nameplate cated load and speed. The radius of the fillets in main journal oil holes was identified as an area of potential stress' concentration and careful inspection of this area was prescribed.
MPSL Status At MP&L's request, Bechtel Corporation reviewed the FaAA analysis and conducted an independent dynamic analysis of the crankshaft. Bechtel concluded that the shaft will meet DEMA standards. Torsiograph tests will be conducted to compare operating values with analytical values. During inspections in June 1984, crank fillets were inspected by liquid penetrant and found to be sound.
Further, oil hole fillets on main journals No. 4, 6, and 8 were inspected by liquid penetrant witn no indications noted. Minor scratches were noted on several crank journals. Also, on crank journal No. 4 a slight metal ouildup
, (rodbearing replaced) was noted; it was removed and the journal polished. Ho t and cold crankshaft deflections have been measured and documented and reported to be within TDI and Owners' Group specifications. ;
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PNL Conclusions Based upon the status of PNL's review of the Owners' Group report prepared by FaAA regarding the crankshaft, PNL is not prepared to agree with the FaAA analysis at this time, and has requested further analytical data from the Owners' Group. PNL has also requested that torsiograph tests be conducted at 0%, 25%, 50%, 75%, and 100% rated nameplate loads and rpm. PNL views the torsiograph data as confirmatory to the analysis. PNL concurs that documented hot and cold crankshaft deflections are within TDI and Owners' Group specifica-tions. On this basis, PNL agrees that the crankshaft will be adequate for operation at loads up to and including 185 BMEP and 450 rpm (as described in PNL-5161 Section 4, " Considerations for Interim Licensing").
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9 Component: Turbochargers Part No.: Elliott 90G Owners' Group Report: FaAA-84-5-7 Brief History of Failures Reports of turbocharger thrust bearing problems are limited to the nuclear industry. To date, thrust bearing problems have been reported for San Onofre, Catawba, and Comanche Peak. Nozzle vane and capscrew problems have also been reported; such problems have occurred at GGNS. Misalignment problens resulting in sheared foundation bolts, as well as broken lube oil return lines and mounting welds, have also been experienced at various nuclear power stations.
Owners' Group Status In Report No. FaAA-84-5-7, dated May 1984, Failure Analysis Associates has analyzed the turbocharger thrust bearing problens for the model 90G turbo-charger and has concluded that the problems are due to insufficient lubrication of the thrust bearings during "f ast" starts (i .e., automatic starts for which no prelubrication is provided to the thrust bearing). Several types of startuo lubrication systems have been implemented at nuclear power plants to avoic these problems . One type is a drip system that provides lubrication from the before-and-after (B&A) recirculation system. An alternate type (in use at GGNS) is an auxiliary B&A lube oil pump. This pump is activated prior to any
, planned start and provides the turbocharger bearings with sufficient lube oil to complete fast starts as required for nuclear standby tests.
FaAA states in the above-mentioned report that findings related to nozzle-vane life and nozzle-ring capscrew design will be presented in a following report. Misalignment problems are not addressed in the FaAA report, and are not mentioned as a topic for a following report.
MP&L Status During the June 1984 inspection of the Division I engine, it was dis-covered that two nozzle ring capscrew heads and one nozzle ring blade were missing on the rign -bank turbocnarger. It was assumed that the capscrew heads 17 l
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had passed through the turbine. On the left-bank turbocharger, one nozzle ring
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- capscrew head had broken off, but was still attached to the locking wire. One nozzle ring blade was also found to be missing. Subsequent inspection of the -
Division II turbocharger revealed one nozzle ring blade missing on each turbo-charger. No broken capscrews were found on Division II turbochargers.
MP&L concluded that missing nozzle ring blades had been removed on pur-pose. The broken capscrews were metallurg1cally examined and the failure mechanism determined to be intergranular stress corrosion cracking, believed to have been initiated by sulfureus compounds in the exhaust gases during shop tests at TDI. An engineering study by MP&L to determine the need for a different capscrew material is underway.
- Division I turbochargers were sent to Elliot for refurbishment, dere the thrust bearings, although still serviceable, were replaced. Nozzle ring blades to replace those missing were also installed on both Division I turbochargers.
MP&L has taken extensive actions to correct vibration problems and is confident that earlier misalignment problems resulting in sheared foundation bolts, as well as broken lube oil return lines and mounting welds, are solved through proper alignment.
PNL Conclusions On the basis of information presented in the FaAA report referenced above, the transcript of the meeting among representatives of FaAA, the Owners' Grouo, NRC, and PNL on June 22, 1984, and the inspection data presented by MP&L, PNL concludes that the action taken at GGNS to provide lubrication to turbocharger bearings is adequate for the first refueling cycle. Key considerations in support of this conclusion are as follows:
! e According to Failure Analysis Associates, as confirmed in a telephone 4 conversation between PNL (W. Laity) and FaAA (T. Thomas) on July 20, 1984, the shortest known time-to-failure of a turbocharger thrust bearing subjected to " dry" starts (for which no bearing prelubrica-tion was provided) occurred at the Shoreham Nuclear Power Station.
That bearing experienced at least 62 " dry" starts before' f ailure.
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. * - On the basis of operating experience at GGNS,over a 2-year period, MP&L estimates that the diesels may experience two " dry" starts per diesel per year. Turbocharger thrust bearings examined from the )
Division. I engine after two " dry" starts showed no evidence of distress. Float measurements of thrust bearings in the Division.II engine are well within manufacturer's specifications, also indicating no thrust bearing distress.
PNL has also reviewed the MP&L actions regarding turbocharger realignment and notes that in excess of 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> af operation have occurred without incidents attributable to misalignment or vibration. PNL concludes that MP&L has taken appropriate actions to correct misalignment problems.
In addition, PNL has reviewed the MP&L conclusion that service-related conditions are not responsible for the missing nozzle ring blades. The fact that one blade is missing from each of four nozzle rings (both engines) and that there is a high probability of damage to the turbocharger if the vane
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breaks in service (not seen on inspection) supports the MP&L conclusion.
( On the basis of the above-mentioned analyses, inspections and reviews, PNL concludes that the turbochargers are acceptable for the first refueling cycle.
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i Component: Connecting Rod Part No.: 03-340A Owners' Group Report: FaAA-84-3-14 Brief History of Failures Connecting rod failures have been reported from the non-nuclear field.
Two failure modes have been observed. The first mode was link rod bolt failure due to loss of bolt preload. The second mode of failure was fatigue cracking of connecting rod bolts and/or the link rod box in the mating threads. No connecting rod failures have occurred in nuclear service.
Owners' Grouo Status The first failure mechanism is fatigue failure of the link rod bolts resulting from loss of bolt preload. The problem and its solution were addressed by TDI in Service Information Memo No. 349, dated September 13, 1980 (pp. 1-3). According to this SIM, engines manufactured between 1972 and February 1980 may have been shipped with an insufficient locating dowel counterbore depth in the link rod or link pin, resulting in clearance between the link rod and link pin as assembled. Under firing load, this locating dowel will yield, allowing the above clearance to cisappear and resulting in loose link rod bolts. The Owners' Group (through the above-mentioned FaAA report) has determined that there must be zero clearance under the specified bolt torque of 1050 ft-lb, and they recommend that the utilities check the clearance with a 0.0015-in feeler gage.
The second failure mechanism is fatigue cracking of the connecting rod bolts and/or the link rod box in the mating threads. TOI attributed these rod cracks to " thread fretting". This " thread fretting" was concluded by TDI to result from distortion of the rod bolt under operating loads in the area of :ne mating threads; the distortion could occur if the bolts had been installed with the originally specified bolt preloads. The Owners' Group addresses this concern for the two versions of the connecting rod, namely the original design, equipped witn 1-7/8-inch bolts and a later design in which the rod boxes are equipped with a 1-1/2-inch bolts. Stress analysis, including finite element, 20
has been completed by FaAA. Failure Analysis Associates has concluded that both designs are adequate for the service intended, provided conrod bolt preload is checked within time limits specified as related to engine load requirement in terms of percentage of nameplate rating. However, the rod with the 1-1/2-inch bolts has an 8% to 9% higher margin of safety than the rod with 1-7/8-inch bolts because the rod box structure is more massive with the smaller bolt configuration.
MP&L Status ,
With regard to the link rod / link pin clearance, MP&L has performed the Owners' Group recomended measurements described above.
The status of the fatigue cracking in the rod boxes is as follows. Both
, Division I and II conrods are equipped with 1-7/8-inch conrod bolts. During the June 1984 inspection, all connecting rods and accessory equipment were inspected; the findings and dispositions are as follows:
e Serrated joint teeth surfaces were 'found to have minor fretting on
- all conrod boxes. At NRC's regoest, the serrated teeth were dressed via stoning and the contact surface verified by " blueing" as per TOI specifications.
- Conrad external machined surfaces were inspected by MP&L and revealed no indications.
- Magnified borescopic inspection of female threads indicated pitting in one hole of No.1, galling in one hole of No. 6, and heavy galling in one hole of No. 5. All conditions were judged to be maintenance-rather than service-induced. Rod No. 5 was replaced and threads in the other rods were tapped and reinspected.
e Conrad bolt inspection revealed that approximately 50% of tne bolts had minor galling, which was judged to be maintenance-related. All bolts were replaced with fully inspected new bolts. When bolts were installed, tney were properly lubricated as per instructions. Proper preload was ascertained by ultrasonic methods.
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. e All conrod dimensions were checked and found to be within specified tolerances . All wrist pin bushings were inspected by liquid pene- '
trant and found to be in good condition. MP&L has proposed to check conrod bolt preload after 270 hours0.00313 days <br />0.075 hours <br />4.464286e-4 weeks <br />1.02735e-4 months <br /> operation or at first refueling, whichever comes first.
PNL Conclusions pML concurs with the MP&L resolution of the connecting rod problem result-i ing from link rod / link pin clearance, namely feeler-gage confirmation that no clearance exists.
Relative to the fatigue cracking in the rod bolts and/or the link rod box, j PNL has reviewed all available information on the subject, and concludes that, provided the check on conrad bolt preload is carried out after 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> of operation or after 9 months, whichever comes first, the conrods are acceptable for the first refueling cycle.
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Component: Engine Base and Bearing Cao Part No.: 03-305C, CSG Class A Owners' Group Report: FaAA-84-6-53 ,
Brief History of Failures The only failure reported by the Owners' Group for OSRV-16 engines occurred in a non-nuclear application: a nut pocket failed on a OSRV-16 engine at the ANAMAX mine near Tucsca Arizona. According to FaAA, the engine manu-
, facturer (TOI) reported that this failure was due to impurities in the casting material that reduced the engine base strength.
l Owners' Group Status Failure Analysis Associates has analyzed the base, bearing saddles, bearing caps, nut pockets, and bolting / nuts. FaAA has concluded that the base assembly components have the strength necessary to operate at full rated load for indefinite periods, provided that all components meet their specifications, that they have not been damaged, and that proper preloads are maintained, i
MP4L Status During the June 1984 inspection liquid penetrant techniques were used on the main bearing cap-to-engine base saddle surf aces on main bearings No. 4, 6, and 8. No relevant indications were observed. '
PNL Conclusions Based upon PNL's review of the Owners' Group report and the engine inspection findings reported by MP&L, PNL concludes that the engine basa assembly is acceptable for the first refueling cycle.
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Component: Cylinder Head part No.: 03-360A Owners' Group Report: FaAA-84-15-12 Brief History of Failures Numerous reports on cylinder head failures are available from both the nuclear and non-nuclear industry. For identification purposes, TDI cylinder heads are classified as I, II, and III, all under tne same part number. Group I are heads cast prior to October 1978; Group II are heads cast between October 1978 and September 1980; and Group III are heads cast after September 1980.
Most instances of cracked heads have involved Group I. Only five instances of water leaks in Group II and III heads have been reported, all in marine applications. Many of the cracks initiated at the stellite valve seats.
Owners' Grouo Status Failure Analysis Associates mechanical and thermal stress calculations, which did not include finite element calculations, concluded that Group I, II, and III heads as designed are adequate for the service intended. The report recommends that Group I and II heads be inspected by liquid penetrant and magnetic particle as well as ultrasonic testing to determine firedeck thickness. For Group III heads, sample inscection as described above is recommended. For all three groups of heads, barring over before startup is recemmended.
Mp&L Status During the June 1984 inspection, all heads (all of wnich are believed to be Group I) eq Oivision I engines were inspected in accordance with Owners' Group recommendations. Eleven heads met all Owners' Group acceptance criteria. Five heads needed further engineering evaluation before being accepted. Mp1L proposed to bar the engine over 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after engine shutdown, and once weekly thereafter. Routinely, the engine will be rolled over prior to a planned start.
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, PNL Conclusions PNL has reviewed all the pertinent material and also notes that MP&L will limit the engine load during the first refueling cycle to that corresponding to 185 BMEP. On these bases, PNL concludes that the cylinder heads are acceptable for the first refueling cycle, provided that the engine is rolled over 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after shutdown, 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after shutdown, and thereafter prior to each planned
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start, to check for water leakage into the cylinders.
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. Component: Jacket Water Pumo
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Part No.: 03-425 Owners' Group Report: Stone & Webster, June 1984 Brief History of Failures Shoreham has experienced a jacket water pump shaft failure on the TDI R-4 engine. There is no history of failures on jacket water pumps designed for the V-16 engines.
Owners' Group Status Stone S Webster has investigated this design jacket water pump and has concluded that, provided proper care is taken to ensure minimum and maximum torque when installing the nut holding the external spine in the taper, the jacket water pump is adequate for the service intended.
MP&L Status No problens have been experienced.
PNL Conclusions Based upon the absence of adverse experier.ce with water pumps designed for the V-16 engines, as well as on the review of the Stone & Webster report, pNL concludes that the jacket water pump is acceptable for the first refueling cycle.
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Component: Engine Mounted Electrical Cable Part No.: 03-6888 Owners' Group Report: Stone & Webster, June 1984 Brief History of Failures No failure of this part has been reported. However, in TOI Service Information Memo No. 361, TOI reported that three engine mountad cables associated witn 1) the Woodward governor / actuator, 2) tne Air-Pax magnetic pick-up, and 3) the Air-Pax t'acnometer relay, represent potential fire hazards.
Owners' Grouo Status Stone & Webster carried out a field survey. Based on the survey results, Stone & Webster concluded that Class 1E IEEE 383-1974 qualified cable, as now installed in both the Division I and II engines, meets the intended function and is acceptable for the required operation.
MP&L Status The original commercial grade cable has been replaced by Class 1E IEEE 383-1974 qualified cable in botn Division.I and II engines.
PNL Conclusions PNL concludes that the Class 1E IEEE 383-1974 qualified cable as installed is acceptable for the first refueling cycle.
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r Component: Cylinder Block Part No.: 03-315A .
Owners' Group keport: Fa AA-84-5 -4 Brief History of Failures Numerous incidents of cylinder block failures have been reported in the -
non-nuclear field. In the nuclear field, all three engines at Shorehah have cracks in their cylinder blocks. At Comanche Peak, cracks were observ4d after 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> of operation.
Owners' Group Status Failure Analysis Associates performed strain gauge testing combihbd with two-dimensional analytical modeling of the block top and liner. Based on these efforts, FaAA concluded:
- Eventually, depending upon load and operating hours, cracks willN initiate between stud hole and line counterbore. Cracks are 4 predicted to be benign.
- Cracks between stud hole and liner counterbore will increase liR111-hood of cracks developing between stud holes of adjacent cylindett.
The deepest crack measured in this region (5-1/2 incnes in depths'at Shoreham) did not degrade engine operation or loosen studs. '(
- Provided there are no cracks between stud holas between adjacent'f cylinders, the bicck is predicted to have sufficient margin to 51 withstand a LOOP /LOCA event.
. The FaAA report recommends inspections of cylinder blocks at intstvals related to load and operating hours.
MPAL Status At the June 1984 inspection, the Division ! cylinder block was ihspected in all critical areas by liquid penetrant as recommended by the Ownetic Group. No critical indications were observed.
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PNL Conclusions .
After reviewing the FaAA report, and noting that MP&L found ho significant indications on the cylinder block and, further, that MP&L will limit the engine load to that correspondiong to 185 BMEP, PNL concludes that the cylinder block is acceptable for the first refueling cycle, subject to the periodic surveillance proposed by MP&L in Section 6.2 of their July 5 submittal.
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. Component: Cylinder Liner Part No.: 02-315-02-0G 0wners'. Group Report: FaAA 84-5-4 r
- G *~ T i Brief History of Failures Only one, incident of cylinder liner failure is available. This failure occurred in 1982 at Grand Gulf when a piston crown separated from the skirt during testing of the Division II engine.
Owners ' Group Status The Owners' Group has identified incorrect cylinder liner dimensions as being a contr'16Lting factor in liner stresses.
MPSL Status ~
C
. DuriAg.the June 1984 inspection all liners were inspected, deglazed, and reinstallea. Df,mensional inspections of the liners were performed by MP&L to
([ ensure that the clamping force of the cylinder head on the liner would not i
induce excessive stress on the cylinder block.
PNL Conclusions ,
,., , Based upon the MPAL inspection and determination of correct dimensions, as well as upon PNL's ansi,te inspection during the June 1984 plant visit, PNL concludes that the 1EAges are acceptable for the first refueling cycle.
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3.2 ' PLANT-SPECIFIC PROBLEMS Component: Low-Pressure Fuel Lines Brief History of Failures On September 4,1984, the Division I engine was stopped due to a fire that broke out at the engine. The fire was caused by a break in a 1-inch fuel oil supply header. MP&L investigated the failure and concluded that it was due to the absence of a clamp, resulting in excessive vibration.
MP&L Status MP&L designed and installed a tubing support for this section of tubing on both Division I and II engines. Vibration tests indicated vibration levels to be well within normal levels for this type of machinery.
PNL Conclusions
{ PNL has reviewed the pertinent MP&L report and determined that the cause of the failure is well understood and that MP&L has taken appropriata correc-tive action. Therefore, PNL concludes that the low-pressure fuel lines are properly supported and are acceptable for the first refueling cycle.
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. Component: Crankcase Caoscrews Brief History of Failures During a 24-hour run of the Division II engine on March 15,1982, the generator was damaged by the head of a 15/16-inch crankshaft capscrew that broke off, found its way into the generator, and became embedded in the stator.
MP&L analysis of the capscrew concluded that the failure was due to a low-
, cycle stress fatigue front expanding from an initial small crack. The failed 3
capscrew also had a decarburized skin, which may have contributed to the' failure. Vibratory tests indicate _that vibrations during startup and shutdown
- . may be contributory to capscrew failure.
MP&L Status
.MP&L has installed protective screens at the generators of both Division I and II engines. MP&L has also provided for proper preload of crankcase caoscrews to be measured periodically.
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PNL Conclusions PNL concludes that, although capscrews may continue to fail from time to time, this no longer represents a problem for the generators because the protective screen has been installed to pr2 vent broken capscrews from entering
, the generator. Therefore, PNL recommends that the crankcase capscrews be accepted for the first refueling cycle.
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Component: Fuel Oil Leaks: Air Start Valve Failures: Air Start Valve Solenoid Failures: Fuel Oil Injection Pumo: and Division I
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Engine Failures to Start Brief History of Failures Failures of all the above five items were recorded in GGNS Division I and II engine logs.
Cause of Failure and Utility' Status All the above items were discussed at the July 13, 1984, meeting among NRC, MP&L, and PNL. For each issue MPSL orally explained the cause of the problem and corrective action taken. MP&L agreed to furnish NRC with documentation on the cause of the failures and the corrective action taken.
PNL Conclusions PNL considers.the information provided orally on July 13, 1984, to be
( reasonable. That is, MP&L has adequately determined the causes of the problems and nas taken appropriate actions to correct them. PNL considers the forth-coming MP&L documentation of resolution of the five items to be confirmatory to the July 13 discussions and concludes that these items should not prevent the Division I engine from being accepted for the first refueling cycle.
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, 4.0 ANALYSIS OF THE REQUIREMENT FOR DIVISION II ENGINE INSPECTION In tne Safety Evaluation Report accompanying the NRC Order of May 22, 1984, requiring diesel generator inspection, the NRC staff stated that the' need for Division II engine inspection would be contingent upon:
- 1. .results of the inspection of the Division I engine
. 2. MP&L's ' ability to demonstrate, through a review of the manufacturer's OA records, that the two engines have similar "as-manufactured" quality.
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4.1 DIVISION I ENGINE INSPECTION RESULTS Conclusions reached by PNL regarding the Division I engine inspection are provided in Section 3 of this TER. In summary, the Division I engine can reliably serve as a standby power source for the first refueling cycle, subject to load limitations and supported by an enhanced surveillance and maintenance program.
! 4.1.1 PNL Evaluation The PNL onsite inspection and the MP&L report of July 5,1984, revealed only one component, the turbocharger, in which failed elements, bolts and a vane, might be expected to occur in the Division II engine. The other components showed no rejectable indications or incipient problems that suggested adverse conditions might be present in the Division II engine.
4.1.2 PNL Conclusion The turbocnargers from the Division II engine should be inspected, any corrective actions taken, and findings documented. No other Division II inspections are recommended on the basis of the Division I results.
4.2 ENGINE SIMILARITY DEMONSTRATION MP&L performed a review and assessment that included the following l considerations:
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t e the similarity of the design and as-manufactured quality of the two diesel engines e . the similarity of the post-manufactured upgrades accomplished for each of the two engines e a comparison of the operating history and operational performance of the two engines -
e- a comparison of the results of the previous inspections of the two engines.
4.2.1 PNL Evaluation The " comparability" review was thorough and did not reveal any engine components where differences between Division I and II would significantly affect the Division II engine performance. It was reported that the crankshafts were manufactured by different vendors. Both vendors are judged adequate by the PNL consultants. The difference noted in the oil hole fillets (7/16 inch in Division I versus 3/16 inch in Division II) was noted. MPSL stated in the July 5,1984, submittal that FaAA analysis . concluded that oil hole radius contributes little to the stress concentration. The PNL consultants believe this conclusion is reasonable.
The engine upgrades (installation of AE piston skirts and friction-welded push rods) on Division I were also implemented on Division II. Thus , the two engines are comparably equipped.
The engine operating records supplied by MP&L in the July 5,1984, submittal indicate that the Division II engine has about 667. fewer starts and 36". less run time than Division I. Further, there is no pattern to valid failures to start that would suggest the Division II engine is significantly less reliable than Division I. PNL notes, however, that the connecting roos have been subjected to approximately 200 hnurs of operation since the bolt preloading was last checked.
4.2.2 PNL Conclusions On the basis of tne review conductea by MP&L on the manufacturer's CA reco-ds and the upgrade accomplished for both engines, PNL concludes that the r
35
1
. l Division I and II engine components are of comparable "as-manufactured" quality. On the basis of the operating history, PNL concludes that the engines
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have been assembled and maintained comparably and the Division II engine has seen less service. Based on these factors and the absence of adverse findings from the recent inspection of the Division I engine, the Division II inspections can be limited to verifying the Division II connecting rod bolt preloading and inspecting the Division II turbocharger, as identified in Section 4.1.2 above.
, PNL assumes that MP&L will impl,ement the same enhanced surveillance and maintenance program on the Division I and II engines to maintain their equivalence.
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. 5.0 REVIEW OF THE POST-INSPECTION TESTING The NRC Order of May 22, 1984, required post-inspection testing to confirm the engines' operability. The testing requirements included the engine manufacturer's recommended preoperational test and additional tests as follows:
e 10 modified starts (a) to 40% load (i.e., 40% of nameplate rating)
- 2 fast starts (b) to 70% of nameplate rating e one 24-hour run at 70% of nameplate rating.
MP&L's letter (AECM-84/0325) to, NRC of July 2,1984, provided NRC with MP&L clarifications / interpretations of the required testing. The tests accomplished are:
4-e 10 modified starts to 50% load o 2 fast starts, started manually from the control room with
, demonstrated load sequencing and shedding, to 70% load e one 24-hour run at 70% load.
5.1 PNL EVALUATION MP&L reported successfully accomplishing all engine manufacturer-recommended post-maintenance testing and all NRC required testing. PNL had understood the fast starts would be done without manual prelubing of the turbochargers . However, the MP&L clarification / interpretation letter (AECM-
, 84/0325) dated July 2,1984, stated that "all engine starts required by the Order will be preceded by a prelube period...". Such starts are not recognized as simulating starts accompanying loss of offsite power.
5.2 PNL CONCLUSIONS PNL concludes that post-inspection testing was satisfactorily accomplished l - with the exception that the fast starts did not simulate the worst challenge to
-the turbocharger bearings. PNL does not recommend additional testing to (a) A modified start is a start including turbocharger prelube and a 3- to 5-minute loading to the specified load and run for a minimum of one hour.
(b) A fast start simulates ESF signal with the engine in ready-standby status.
37
. . - . , . - -r - - , - - - - m -- .- , e,-
simulate this challenge, The information cited earlier in this report for turbocharger thrust bearings provides assurance that the number of " dry" starts anticipated by MP&L is small'(two per year per engine), and that the thrust bearings may reasonably be expected to operate satisfactorily for many more
- than the anticipated number of " dry" starts through the first refueling cycle.
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.- - - - - - - - - . , , - _ . , ., n- -- - ~ - -
, 6.0 REVIEW OF THE PROPOSED AUGMENTED MAINTENANCE / SURVEILLANCE PROGRAM s
In a letter dated April 16, 1984, to C. Berlinger, PNL identified elements of a maintenance / surveillance (M/S) program that would provide added assurance that the performance of key components of the GGNS TDI engines would be regularly reviewed and that early data would be available to detect potential component failures. It was felt that, in the absence of the completed Owners' Group Program Plan, enhanced M/S is needed to ensure engine reliability.
, Clarification of some elements of the M/S program was provided to NRC in a letter to C. Berlinger dated April if,1984. Subsequently, the features of the enhanced M/S program suggested by PNL were incorporated by the NRC staff in a
.- letter to MP&L dated April 25, 1984 The MP&L submittal of July 5,1984, proposed an augmented M/S program for the GGNS Unit i diesel engines. MP&L proposed that this revised program remain in effect "...until such time that the reliability of the TDI engines has been demonstrated as adequate by,MP&L and the TDI. 0/G Owners' Group to- the satisfaction of the NRC." The MP&L proposed program differs somewnat from the NRC staff recommendations. The differences are aimed at reducing the time that J
the engines would not be availaole while the GGNS is at power. Table 1 provides a comparison of the NRC and MP&L M/S program elements.
6.1 PNL EVALUATION f
PNL has recommended that utilities seeking licensing prior to the Owners' Group completing all elements of their plan should provide for enhanced surveillance and maintenance (see Section 4 of PNL-5161). Generally, MP&L has
, provided this. However, as evidenced in Table 1, there are significant differences between the NRC guidance of April 25 and the July 5 proposal oy
, MPAL.
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I TABLE 1. Comparison of NRC and MP&L Proposed Maintenance / Surveillance for Key Components of the GGNS TOI Engines Component NRC Guidance (Aoril 25) MP&L Procosal (July 5)
Cylinder heads Air roll 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after engine Air roll 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after runs and each day thereafter engine runs and each week thereafter Engine block Visually inspect after Same as NRC and base 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> operation or monthly Connecting rods Visually inspect' and retorque Visually inspect and after 24 starts. 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> retorque after 50 starts, operation, or 6 months, whichever 270 hours0.00313 days <br />0.075 hours <br />4.464286e-4 weeks <br />1.02735e-4 months <br /> operation, or is first at the first refueling outage, wnichever is first Lube oil check Check for water following Monthly checks preoperational tests, then weekly or after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> oper-ation, whichever is first.
Check monthly for contaminants and water in sump; check filters Studs /fi xtures Check 25% monthly for torque Check 25% after 270 hours0.00313 days <br />0.075 hours <br />4.464286e-4 weeks <br />1.02735e-4 months <br /> or at the first refueling outage, whichever is first Push rods , cams , Visually inspect after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Visually inspect after 270 tappets , etc. operation hours operation or at the first refueling outage, whichever is first Other M/S items Standby: Standby:
Luce oil filter differential Luce oil filter differen-pressure - daily tial pressure - hourly Crankshaft deflections - Crankshaft deflection -
6 months after 270 hours0.00313 days <br />0.075 hours <br />4.464286e-4 weeks <br />1.02735e-4 months <br /> or at 4
refueling Ooerations: Ooerations:
Exnaust temp. - continuous Generally per NRC guidance (record hourly)
Lube oil, jacket water, interlock temp., air pressure, accelerometers - continuous (record hourly) 40
, 6.1.1 Cylinder Heads The engine air-roll is to detect water in the cylinder, indicating cracked cylinder heads. Water in the cylinder would seriously impact engine operabil-ity. Th3 MP&L proposal is to air roll weekly.rather than daily to reduce engine unavailability. PNL does not consider this proposal to be adequate for assuring timely detection of water in the cylinders. A revised schedule of air rolls, tr.cluding one each at 4 and 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after engine shutdown and, there-after, prior to ' planned engine starts, is recommended. The basis for the change from the earlier PNL recommendation (which called for rolling the engine every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) is the recognition that, if a leak has not occurred before 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> downtime, it is unlikely that one will be generated before the next time the engine is operated.
6.1.2 Connecting Rods The visual inspection and retorquing are to provide assurance that the
! serrated rod joint has not loosened, which could lead to engine failure. The relevant Owners' Group report (FaAA-84-3-14) recommends that the bolt 4
retorquing interval not exceed 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> at full load, 248 hours0.00287 days <br />0.0689 hours <br />4.100529e-4 weeks <br />9.4364e-5 months <br /> at 85% load, and 286 hours0.00331 days <br />0.0794 hours <br />4.728836e-4 weeks <br />1.08823e-4 months <br /> at 75% load. The Owners' Group does not differentiate between conrods having 1-1/2-inch bolts and those having 1-7/8-inch bolts (the latter having higher stresses). However, the GGNS conrods have the 1-7/8-inch bolts; theirs is the only V-16 engine in nuclear service with bolts of this size. Add to these factors the observation of some minor fretting in the serrated joints, noted in connection with the latest engine inspection, and a retorquing
- approach more conservative than *J1at proposed by MP&L is recommended. A
, retorquing schedule of 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> of operation or 9 months, whichever occurs 1
l.
first, is considered adequate. The 200-hour retorquing interval (rather than the earlier proposed 50-hour interval) is based on PNL's review of the Owners' Group report and the MP&L analysis of the adverse impact of more frequent inspections on engine availability.
6.1.3 Lube Oil Checks Lube oil checks serve two main functions: they indicate water in the oil that can lead to early engine failures (as well as indicating cracks in engine 41 i
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. l components), and they may be useful for detecting abnormal wear of engine
-parts. In this last regard it is -important to collect the lube oil sample while the engine is running; MP&L did not specifically provide for this. l Otherwise, the proposed monthly rather than weekly lube oil check is considered sufficient, in light of reevaluation based on the experience of the PNL diesel engine consultants.
6.1.4 Studs /Fi xtures Loss of preload on studs can affect engine operability if it goes unnoticed. The air start valve capscrews are more susceptible to loss of preload than are the other threaded fasteners because the gasket material used with these capscrews is softer. One consequence of loss of preload may be loss of cylinder compression.
The MP&L proposed schedule of retorquing on a 25% sampling basis at-270 hours or at the first refueling outage is considered acceptable, based on the judgment of the PNL diesel engine consultants, with the exception of the air start valve capscrews. All (100%) of these capscrews should be retorqued on
< the MP&L frequency.
6.1.5 Push Rods , Cams , Etc.
Engine operability is affected by defects in push rods, cams, ano other similar components. Periodic visual inspection is therefore needed. The difference between the NRC guidance (after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> operation) and MP&L proposal (after 270 hours0.00313 days <br />0.075 hours <br />4.464286e-4 weeks <br />1.02735e-4 months <br /> operation or at the first refueling, whichever is first), is not considered significant in light of the low wear rates of these components, because all parts have been inspected and because, in the opinion
, of the PNL consultants, there is very little enance of changes in the condition.
I of these parts taking place in the 270-hour (versus the 24-hour) time period.
- Therefore, the MP&L proposal is considered acceptable.
Additional Surveillance Surveillance of a number of key engine parameters is essential to assuring reliable engine performance. The NRC guidance and MP&L proposed surveillance are generally quite similar. The differences roted in frequency of measuring l
42
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lube oil pressure difference and hot and cold crankshaft deflection are not of major significance; thus, the MP&L proposals in these areas are acceptable.
Some clarification of the terms used in the MP&L July 5,1984, submittal is recommended. Also, one item of surveillance, engine load, was not addressed. The following changes in Section 6.7 of the MP&L submittal are therefore recommended:
- p. 57, Discussion - add the word " hourly" after " recorded" in line 2.
- p. 58 - replace as noted:
e " lube oil pressure" to " engine inlet lube oil pressure" e " combustion air L.B. pressure" and " combustion air R.B.
pressure" to " air manifold pressure L.B. and R.B."
e " jacket water pressure" to " jacket water pressure in and out" e " cylinder temperatures" to "all cylinder exhaust temperatures" e " stack temperatures" to "preturbine exhaust temperatures" e add " engine load" as a new item.
, p. 59, MP&L Prooosed Action - add "or each refueling cycle, whichever
(
occurs first," after " operation" in line 3.
- p. 59 - Add a new item of surveillance, namely " check the rotor float of at least one turbocharger and inspect stationary nozzle ring bolts, after 270 hours0.00313 days <br />0.075 hours <br />4.464286e-4 weeks <br />1.02735e-4 months <br /> of operation or at the first refueling outage, whichever comes first."
- p. 64, Table 6 add " clear water system (flush out)" with frequency of 3 to 4 years.
6.2 PNL CONCLUSIONS PNL concludes that the MP&L propused M/S activities need some modifica-tions tb provide adequate assurance of engine reliability / operability. The modifications are discussed in detail above in Section 6.1. In summary they are:
o cylinder heads - Revise air roll to 4 and 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after each engine shutdown and prior to planned engine starts.
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e connecting rods - Revise retorquing frequency to 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> or s
9 months, whichever occurs first. A retorquing check should -be performed on the Division II engine prior to plant operation.
e -lube oil checks - Add that a lube oil sample will be obtained while engine is running.
e studs / fixtures - Modify to assure that 100% of the air start valve capscrews will be retorqued on the schedule indicated.
e additional surveillance - Provide changes as detailed above in Section 6.1.6.
With these modifications, the MP&L proposed M/S activities are considered acceptable for the first refueling cycle.
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- - . - _ _ _ _ _ _ _ _ _ _ _ _ - - - - - - - - - -r - - - + " TT
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7.0 OVERALL CONCLUSIONS PNL and its consultants conclude that the TDI diesel engines at the GGNS have the needed operability and reliability to fulfill their intended (auxiliary) emergency power function for the first refueling cycle. This conclusion is reached with a number of understandings regarding 1) limits to the engine requirements, 2) NRC concurrence with MP&L findings / conclusions regarding items to be supplied to NRC, 3) limitations on the engine Brake Mean Effective Pressure (BMEP), and 4) MP&L's implementation of the modifications to their proposed surveillance and maintenance program identified in Section 6.
Further details on these items follow.
7.1 LIMITED ENGINE RE0VIREMENTS PNL understands that the emergency service requirements MP&L now foresees for the GGNS will not exceed the engine load corresponding to a BMEP of 185 psig.
( 7.2 NRC CONCURRENCE WITH ADDITIONAL MP&L SUBMITTALS The PNL conclusion that the TDI engines will provide adequate standby power for the GGNS is predicated on an understanding that a technical review of the following MP&L submittals to NRC will not raise unanticipated problems':
e an inspection report confirming that the turbocharger turbine nozzle bolt failure was due to intergranular stress corrosion e a submittal describing in detail the method used and the results to confirm the surface area contact of the serrated surfaces of eacn connecting rod is at least 75".
e documented results of measurements of the cylinder head firedeck i surface flatness e the inspection and engineering evaluation reports confirming the acceptability for continued service of the two cylinder heads that contain cracks in the stellite seats e a submittal identifying the design of cylinder head replacement studs 45
g,.
l e MP&L documentation of the ' indications noted and the engineering disposition concerning the relative motion between the piston crown and skirt e documented crankshaft deflections relative to TDI specifications
! e crankshaft torsiographs at 0%, 25%, 50%, 75% and 100% of engine-nameplate loading and associated stresses as identified in a PNL letter to NRC dated July 17, 1984 e documented preturbine exhaust temperatures relative to the manufacturer's recommended maximum.
7.3 ENGINE BMEP LIMITATIONS PNL understands that all subsequent engine testing (except the above-mentioned torsiograph at 100% loading and the test to obtain preturbine exhaust temperature data) will be limited to the load corresponding to 185 BMEP.
7.4 REVISED SURVEILLANCE / MAINTENANCE PROGRAM PNL understands that MP&L will resubmit to NRC a revised surveillance and maintenance plan incorporating the recommended changes identified in Section 6 of this report.
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f PNL-5201
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' DISTRIBUTION No. of No. of Cooies Copies 0FFSITE 2 00E Technical Information Center 17- Division of Licensing Office of Nuclear Reactor K. Trickett, NE-14 Regulation U.S. Department of Energy U.S. Nuclear Regulatcry Office of Nuclear Energy Commission Washington, DC 20555 Washington, DC 20555
ATTN: C. Berlinger (10)
ONSITE M. Carrington (2)
R. Caruso 00E Richland Goerations Office
.. D. Corley D. Eisenhut M. Plahuta F. Miraglia M. Williams Pacific Northwest Lacoratory 12 NRC Plant Project Managers 5 Consultants Division of Licensing U.S. Nuclear Regulatory A. Henriksen Commission B. Kirkwood Washington, DC 20555 P. Louzecky ATTN: B. Buckley A. Sarsten S. Burwell J. Webber D. Hood O. Houston 5 Senior Review Panel K. Jabbour T. Kenyon R. Albaugh E. McKenna S. Bush
. M. Miller C. Hill S. Miner W. Richmond C. Stable L. Williams J. Stefano E. Weinkam 30 Project Team 2 NRC Divisien of Technical J. Alz:1eimer
' Information and Document M. Clement Control S. Danigren Washington, CC 20555 0. Dingee R. Dodge NRC Public Document Room W. Gintner W. Laity (15)
J. Nesbitt F. Zaloudek l Technical Information (5)
Publishing Coordination (2)
Distr-1
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.o - Attachumnt 3 SAFETY EVALUATION REPORT CATAWBA NUCLEAR STATION UNIT 1 RELIABILITY OF DIESEL GENERATORS 1
MANUFACTURED BY TRANSAMERICA DELAVAL, INC.
l TDI PROJECT GROUP DIVISION OF LICENSING
1.0 INTRODUCTION
In support of its request for a full power license for Catawba Nuclear Station (Catawba), Unit 1, Duke Power Company (the licensee)
June 29, 1984, a description of the inspection results ubmitted by letter dated of the 1A diesel generator. Further, on July 6, 1984, the licensee submitted its inspection plans for the 18 engine along with its proposed return-to-service testing of the 1A engine. The licensee submitted its enhanced maintenance and surveillan~ce program for the diesels on July 16, 1984.
Both diesel generators at Catawba Unit 1 (designated 1A and 18) have 16 cylinders in the vee configuration with a full load engine rat'ng of 7000XW.
The engine manufacturer is Transamerica Delaval, Inc. (TDI).
2.0 BACKGROUND
Concerns regarding the reliability of large bore, medium speed diesel generators of the type supplied by TDI at Catawba Unit 1 and at-fifteen (15) other domestic nuclear plants were first prompted by.a crankshaft failure at Shoreham in August 1983.
However, a broad pattern of deficiencies in critical engine components have since become evident at other nuclear and non-nuclear facilities employing TDI diesel generators. These deficiencies stem from inadequacies in design, manufacture and QA/QC by TDI.
In response to these problems, thirteen (13) U.S. nuclear utility owners, including the licensee, fonned a TDI Diesel Generator Owners Group to address operational and regulatory issues relative to diesel generator sets used for standby emergency power. The Owners Group program, which was initiated in October 1983, embodies three major efforts.
1.
Resolution of 16 known generic problem areas (Phase I program) intended by the Owners Group to serve as an interim basis for the licensing of plants.
- 2. Design review of important engine components and quality revalidation of '
important attributes for selected engine components (Phase II program).
- 3. Identification of any needed additional engine testing or ins t
based on findings stemming from the Phase I and II programs. pections, l
e 3.0 EVALUATION t
Enclosure 1 to this SER is a Technical Evaluation Report (TER) entitled,
" Review and Evaluation of Transamerica Delaval, Inc. Ofesel Engine Reliability and Operability - Catawba Nuclear Station, Unit 1." This TER was prepared by Pacific Northwest Laboratory (PNL) which is under contract to the NRC to perform technical evaluations of the TDI Owners Group's generic program, in addition to plant-specific evaluations relating to the reliability of TOI diesels. PNL has retained the services of several expert diesel consultants as part of its review staff.
In addition to the submittals listed in Section 1.0 above PNL and its consultants also reviewed other licensee submittals (identified in Section 2.0 of the enclosed TER) and performed onsite inspections of key engine components in April and July,1984, while the 1A and IB engines were disassembled, respectively. 1 PNL and its consultants also considered the status of the generic Owners Group program relative to the actions taken by the licensee to establish the reliability of the diesels. .
The staff has reviewed the enclosed TER, and adopts the TER as part of this Safety Evaluation by reference. The remainder of the SER provides clarification 1 of the TER and indicates items required of the licensee. ;
3.1 Extended Operational Tests i In an April 5,1984 letter to the NRC, Duke Power Company described their extended operational tests on the 1A engine. The 1A engine had been operated to over 810 hours0.00938 days <br />0.225 hours <br />0.00134 weeks <br />3.08205e-4 months <br /> with about 76% of those hours at operating levels greater than required for emergency power.
(and subsequently the IB engine) for this 6 mount of time was to establish t reliability and operability of the engine. The IB engine has also been tested to greater than 750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br /> with more than 75% of the tests conducted at full load or above and approximately 80% of the tests conducted at operating levels greater than required for emergency power.
3.2 _ Inspections Following Extended Operational Tests 3.2.1 1A Engine Following the extended operational tests, the licensee conducted an extensive teardown and inspection of the 1A engine which presently is almost complete.
The inspection of key engine components, including those identified by the Owners Group as known potential problem areas, indicates that these components are acceptable for nuclear service for the interim period extending to the first refueling of Catawba Unit 1. This finding is subject to (1) operating restrictions as identified in Section 3.5 of this SER, and (2) completion of Itcensee actions pertaining to confirmatory issues as identified in Section 4.0 below.
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3 The most significant findings as a result of this inspection include cracks in four of the AN type piston skirts (all pistons in both engines have been replaced with the later model AE skirts), wear on the turbocharger thrust bearings, cracks in two intake rocker arm pedestals, small jacket water leaks in two cylinders, and three minor indications on the crankshaft which were polished out.
i In~a June 29, 1984 submittal, Duke Power discussed their inspections and their evaluation and final disposition of findings. For the most part, the staff has i
concurred with Duke Power's assessment and resolution of inspection results.
However, the staff has no basis to find that Duke Power's solution to preventing weld cracking on the right bank at the turbocharger adapter to the intercooler interface, i.e., providing stiffeners to span th,e weld area, is adequate considering the amount of surging and vibration that this interface is likely to experience. The staff believes a solution which would alleviate this problem involves installation of a flexible joint at this juncture. Because
! of the potential impact to operation that failure at the adapter could have, the staff requires Duke Power to install a flexible joint arrangement at the turbocharger right bank of both engines prior to operation above 5% power.
Additionally, Duke Power must install an improved turbocharger prelubrication system by first refueling, or in lieu of installation, must fully inspect the f turbocharger thrust bearings of one engine at the first refueling. Duke Power 1
has comitted to install an improved system by September 1984. In addition, prior to operation above 5% power, Duke Power must comit to perform such an inspection if an improved prelubrication system is not installed.
Duke Power has indicated in their June 29, 1984 inspection report that #6L cylinder head will be replaced. The staff requires that this head be replaced prior to operation above 5% power with either a new cylinder head or one obtained from another engine such as those at Catawba Unit 2.
There remains several plant-s'pecific and generic problem areas where Duke Power has not yet completed the inspection.or where investigation is
, continuing. Satisfactory completion and resolution of these areas must be i
confinned to the staff prior to full power licensing of Catawba. Confirmation
, is required of the following:
- Satisfactory reassembly and walkdown results for the fuel line fittings, Satisfactory inspection results, including necessary replacement of fuel
- injection pump valve holders,
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- Replacement of turbocharger gas inlet bolts,
- Satisfactory results of eddy-current testing of high pressure tubing, and Installation of the jacket water pump impeller nut within the recommended
! torque range.
3.2.2 IB Engine The inspections perfonned on the 18 engine are identified in a July 6,1984 letter to the NRC and are also quite thorough and extensive. They are very similar in scope to those performed on the 1A engine. The justification for reduced inspection of some components is based on satisfactory results on the_
. a, L .
l The most significant findings as a result of this inspection include cracks in four of the AN type piston' skirts (all pistons in both engines have been replaced with the later model AE skirts), wear on the turbocharger thrust bearings, cracks in two intake rocker am pedestals, small jacket water leaks in two cylinders, and three minor indications on the crankshaft which were polished out.
In a June 29, 1984 submittal, Duke Power discussed their inspections and their evaluation and final disposition of findings. For the most part, the staff has concurred with Duke Power's assessment and resolution of inspection results.
However, the staff has no basis to find that Duke Power's solution to preventing weld cracking on the right bank at the turbocharger adapter to the intercooler interface, i.e., providing stiffeners to span the weld area, is adequate considering the amount of surging and vibration that this interface is likely to experience. The staff believes a solution which would alleviate this problem involves installation of a flexible joint at this juncture. Because of the potential impact to operation that failure at the adapter could have, the staff requires Duke Power to install a flexible joint arrangement at the turbocharger right bank of both engines prior to operation above 5% power.
Additionally, Duke Power must install an improved turbocharger prelubrication system by first refueling, or in lieu of installation, must fully inspect the turbocharger thrust bearings of one engine at the first refueling. Duke Power has connitted to install an improved system by September 1984. In addition, prior to operation above 5% power, Duke Power must connit to perform such an inspection if an improved prelubrication system is not installed.
Duke Power has indicated in their June 29, 1984 inspection report that #6L cylinder head will be replaced. The staff requires that this head be replaced prior to operation above 5% power with either a new cylinder head or one obtained from another engine such as those at Catawba Unit 2.
There remains several plant-s'pecific and generic problem areas where Duke Power has not yet completed the inspection. or where investigation is continuing. Satisfactory completion and resolution of these areas must be confirmed to the staff prior to full power licensing of Catawba. Confirmation is required of the following:
- Satisfactory reassembly and walkdown results for the fuel line fittings, Satisfactory inspection results, including necessary replacement of fuel injection pump valve holders.
Replacement of turbocharger gas inlet bolts, Satisfactory results of eddy-current testing of high pressure tubing, and Installation of the jacket water pump impeller nut within the recomended torque range.
3.2.2 IB Engine The inspections perfomed on the IB engine are identified in a July 6,1984 letter to the NRC and are also quite thorough and extensive. They are very similar in scope to those perfomed on the 1A engine. The justification for reduced inspection of some _canents is based on satiafastsm cmmlR2 sn Rha
s b o
1A engine.
By letter dated August 1,1984, Duke Power has committed to perform examinations of the IB engine's link. rod bushings for any damage.
As resolution to the problem of chrome peeling on the intake and exhaust valves, Duke Power has ' replaced the affected valve stems where found, on both engines.
The staff and its consultants agree with the licensee's approach. It is not thereplaced.
be consultant's intent in the enclosed TER to suggest that all valves need to The staff concludes that the licensee's proposed 18 inspection plan, as contained in the July 6 and August 1,1984 submittals, is adequate with one modification. Prior to operation above 5% power, the staff requires that Duke Power comit to check the torque of the jacket water pump impeller nut at the time of the first refueling outage.
The staff concludes that the 18 diesel can reliably meet its intended design function based on the proposed inspection plan.
of the IB inspection results by October 31, 1984. The staff anticipates receipt 3.3 Return-to-Service Testing The licensee proposed certain return-to-service tests for the engine in its July 6,1984 submittal to the staff. The purpose of the tests is to demonstrate the engine's operability following reassembly. By letter dated August 1,1984, Duke Power comitted to install temporary thermocouples on the 18 engine to measure pre-turbine exhaust temperatures at 25%, 50%, 75% and 82%
of full engine load during that engine's return-to-service testing program.
In addition, Duke Power has comitted to install permanent thermocouples on both engines by the first refueling outage. The staff and its consultants have reviewed following the licensee's proposed testing and find it acceptable with the modification:
Duke Power must perfonn the tests within the operating restrictions outlined in Section 3.5 of this SER.
The staff concludes that the licensee's proposed testing plan, with the above modification to-service. Ifisasufficient to establish the 1A engine's operability for return-test failure occurs during return-to-service testing, the problem must be corrected and that particular test sequence (e.g. endurance test or modified start tests) must be reperformed.
The staff understands that the testing program for the 18 engine will duplicate that of the exhaust 1A engine with the addition of the monitoring of the pre-turbine temperatures. As with the 1A engine, the staff concludes that successful completion operability for return to ofservice.
the IB testing program will establish the IB engine's-L i
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4 3.4 Enhanced Maintenance and Surveillance Program
- PNL concluded in the enclosed TER that modifications to the Enhanced l
' Maintenance / Surveillance (M/S) Program proposed by the licensee in their July 16, 1984 submittal are needed to provide adequate assurance of engine reliability / operability. These modifications are discussed in detail in Section 7 of the enclosed TER. .
The staff will require that the licensee commit to a modified M/S program as discussed prerequisiteintothis section of a operation the SER above and in Section 7 of the enclosed TER as a 5% power.
- The connecting rod bearing shell inspection called for on page 50 of the enclosed TER should include a complete inspection (dimensional, visual and radiographic) of all bearing shells after 500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> of operation. The bearing shell inspection discussed on page 92 should be a sample inspection of four bearing shells to evaluate their condition in relation to the 500 hour0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> inspection interval.
J Duke Power indicated in its inspection report dated June 29, 1984, that until j the cause of the rocker box subassembly cracking was determined, the sub-
~ assemblies would be inspected regularly. Duke Power must supply to the staff the planned surveillance activities and frequencies of inspections of the 4
subassemblies prior to operation above 5% power. Increased surveillance j
- activities of should the failure continue until to is accomplished identffication and resolution of the cause the staff's satisfaction.
1 The TER specifies an inspection interval for the connecting rod bolting
- of i
1 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> or nine months, whichever comes first. Since issuance of the final TER, pNL has reevaluated the inspection interval in terms of the operating time expected in nine months which is on the order of- 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br />. Their reevalua-tion is contained in an August 10, 1984 letter to the staff provided as an enclosure to this SER. Because the operating time in nine months is not expected to approach 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br />, inspection of the connecting rod bolts at the first refueling outage, rather than nine months, is deemed acceptable. The i
staff agrees with this assessment since the inspection time interval will now correspond more closely with the operating time inspection interval. Therefore,
( the connecting rod bolting should be inspected at 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> or first refueling, whichever comes first.
j The licensee is required to check the lubricating oil of the engine for 4
chemical and particulate contamination on a monthly basis for the first three months of operation at which time the results will be reviewed by the staff to determine a subsequent surveillance schedule.
i The diesel engines at Catawba have li" connecting rod bolting rather than 1-7/8" bolting as identified in the TER.
. : , e, 4
- 6-4 3.5 Operating Restrictions The staff recomendations and conclusions regarding TDI diesel engine 4
reliability at Catawba Unit 1 are predicated on the following:
- 1. Engine operation and testing, including surveillance testing required by the plant Technical Specifications, will be limited to within 5% of the nominal engine load where the upper limit of this load range corresponds to a BMEP of 185 psig. The need for this is based on PNL and staff concerns regarding the acceptability of crankshaft stresse's, and the lack of substantial AE piston operational data at higher BMEP loadings.
I 2. The emergency service requirements of Catawba Unit I do not exceed the engine load corresponding to a, brake mean effective pressure (BMEP) of
- 185 psig.
, 3. At the first refueling, the licensee is required to implement all applicable recommendations of the Owners Group, as reviewed and accepted by the staff. This implementation will be a condition of the license.
1 With regard to item 1 above, the licensee must submit proposed Technical Specification changes incorporating this item prior to operation above 5%
power. Specifically, the proposed chariges would require that the monthly and i 18 month surveillance tests be performed at a load greater than or equal to j the maximum emergenc -
load,185 psig BMEP)y This .
servicelimitload, is greater but notthan to exceed the auto-connected 5750KW (82%loads of rated
{ required for the loss of offsite power and post-LOCA conditions as described 3 below in reference to item 2. Therefore, the staff finds these changes
- acceptable. -
l
! With regard to item 2 above, the 185 psig BMEP corresponds to a generator '
load of approximately 5750KW, slightly more than 82% of full rated load.
4 This exceeds the maximum emergency service loads of 5714KW and 5256KW required i
to shut don the plant and maintain it in a safe condition for loss of offsite power and LOCA, respectively. Thus, there exists sufficient engine capacity j at 1.5 psig BMEP to assure that the fuel design limits and . design conditions l of the reactor coolant system boundary are not exceeded, and that the core is
! cooled and containment integrity and other vital functions are maintained in the event of postulated accidents as required by GDC-17.
l The licensee must add, prior to full power licensing, a precautionary note to
- the Catawba Abnormal Procedure for Loss of Nonnal Power, and to any other applicable plant procedures, to ensure that loads will not be added unnecessarily to the engines in excess of 185 psig BMEP (5750KW). In addition, i future training with respect to this procedure will explain both the basis for
! the note and the aspects to be taken into consideration in its application.
i The NRC will verify that these actions have been completed.
l With regard to item 3, the full power license is being conditioned to require NRC review and approval of licensee actions pertaining to a final resolution i of the.TDI diesel generator. issues at Catawba Unit 1.
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4.0 CONCLUSION
S The staff and its consultants have reviewed the licensee's extended operational test program, its post-operational inspection program, its return-to-service test plan and its maintenance / surveillance schedule. The staff believes that the licensee has adequately tested the engines prior to disassembly and inspection. The inspections perfonned by the licensee were sufficiently broad in scope to encompass both Catawba-specific occurrences as well as the significant generic problems identified by the Owners Group. Further, the staff concludes that upon satisfactory completion of return-to-service testing i
and implementation of the modified maintenance / surveillance program, the Unit 1 engines should be reliable to perform their design functions through the first reactor refueling outage.
Therefore, the NRC staff concludes that the TDI diesel engines at Catawba Unit I will provide a reliable standby source cf ensite oower in accordance with General Design Criterion 17. This finding is based upon the NRC st.aff/PNL review of (1) the current status of the TOI Owners Group Program in resolving
- the TDI diesel engine issue; (2) actions taken by the licensee to enhance and verify the reliability of the 1A and 18 engines (contingent upon satisfactory completion of the IB engine inspections and the 1A and 1B engines' return-to-
. service testing); (3) the enhanced maintenance and surveillance program as described in Section 3.4 of this SER and in Section 7 of the TER which the licensee must comit to; and (4) changes to the Technical Specifications to limit future testing and operation of the engines to a BMEP of 185 psig.
Furthermore, the Catawba license will be conditioned to require Duke Power to implement the Owners Group recomendations applicable to Catawba Unit 1, as reviewed and accepted by the staff, by the plant's first refueling outage.
i As discussed in the SER, the following items are requf red of the licensee prior to operation above 5% power to support the staff's conclusions.
l Installation bank of both of a flexible joint arrangement at the turbocharger right engines.
a A comitment to inspect the turbocharger bearings of one engine if an improved prelubrication system is not installed.
- I j
. Replacement of the 6L cylinder head on the 1A engine.
A comitment to inspect the IB engine's jacket water pump impeller nut at the first refueling.
A comitment to incorporate the modified maintenance and surveillance program as discussed in the SER and TER, including identification of the j rocker box subassembly inspection frequency and cause of failure. I l
Revised Technical Specifications limiting operation and testing to 185 psig BMEP (5750KW).
_ _ . . ~ . _ - - - - . _ _ - , _ . _ . _ _ . . ~ . _ . -
____-m.. . _ . _ __ _ . , . _ _ . _ . _ _ _ . ~ . .
l ;
Revised plant procedures incorporating a precautionary note to ensure that loads will not be unnecessarily added in excess of 185 psig BMEP (5750KW).
Confirmation of the following is required on the 1A inspection prior to operation above 5% power:
Satisfactory reassembly and walkdown results for the fuel line fittings.
Satisfactory inspection results, including necessary replacement of fuel injection pump valve holders.
Replacement of turbocharger gas inlet bolts.
Satisfactory results of eddy-current testing of high pressure tubing.
Installation of the jacket water pump impeller nut within the recommended torque range.
. Enciowe.1 -
PNL-5211 4
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I
. ~
k Review and Evaluation of TransameriCa Delaval, inC.,
Diesel Engine Reliability and
, Operability - Catawba ,
Nuclear Station Unit 1 4
August 1984 Prepared for the U.S. Nuclear Regulatory Commission ~
under Contract DE-AC06-76RLO 1830 NRC FIN 82963 i
Pacific Northwest Laboratory i
Operated for the U.S. Department of Energy by Battelle Memorial institute i
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. DISCLAIMER y
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This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legalliability or responsibility for the accuracy, com-pleteness, or usefulness of any information, apparatus, product, or process
_ e disclosed, or represents that its use would not infrittge privately owned rights.
Reference herein to any specific commercial product, process, or service by trade name, trademart manufacturer, or otherwise, does not necessarily constitute or imply its endorsement. recommendation, or favoring by the T'
United States Government or any agency thereof. The views and opinions of f , i authors expressed here;n do not necessarily state or reflect those of the United
, ,, States Covernment or any agency thereof.
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s PACIFIC NORTHWEST LABORATORY operated by
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_ ' PNL-5211 REVIEW AND EVALUATION OF TRANSAMERICA DELAVAL, INC.,
DIESEL ENGINE RELIABILITY AND OPERABILITY - CATAWBA NUCLEAR STATION UNIT 1
-August 1984 Prepared for Division of Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission under Contract DE-AC06-76RLO 1830 NRC FIN B2963 Project
Title:
Assessment. of Diesel Engine Reliability / Operability NRC Lead Engineer: C. H. Berlinger I l
Pacific Northwest Laboratory Richland, Washington 99352
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PACIFIC NORTHWEST LABORATORY s PROJECT APPROVALS
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, Pacific' Northwest Laboratory
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-Y Date $~ WWY W. O. Richmonc,5 Chairman Senice Review Panel Pacific Northwest Laboratory 6
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CONTENTS 1.0 INTR 000CTION......................................................... 1 1.1 SCOPE OF REP 0RT................................................. 2 1.2 LIMITED APPLICABILITY OF CONCLUSIONS.......................,..... 2 1.3 REPORT PREPARATION.............................................. 3
2.0 BACKGROUND
........................................................... 5 2.1 OWNFRS' GROUP PROGRAM PLAN...................................... 5 2.2 CATAWBA NUCLEAR STATI0N......................................... 6 3.0 EVALUATION OF COMPONENT PROBLEM RESOLUTION........................... 9 3.1 PLANT-SPECIFIC PR0BLEMS......................................... 11 3.2 GENERIC PR0BLEMS................................................ 46 3.3 RESPONSES TO NRC QUERIES ON COMPONENT PROBLEMS.................. 68 4.0 EVALUATION OF CATAWBA 1A DIESEL ENGINE INSPECTION.................... 69 4.1 STATUS AT CATAWBA............................................... 69 4.2 TEST AND INSPECTION RESULTS..................................... 70 4.3 EVALUATION...................................................... 71
4.4 CONCLUSION
S..................................................... 72 5.0 EVALUATION OF CATAWBA 18 OIESEL ENGINE OPERATION TEST AND INSPECTION....................................................... 73 5.1 CATAWBA IB OIESEL ENGINE 0PERATION.............................. 73 5.1.1 PNL Evaluation........................................... 74 i 5.1.2 PNL Conclusions.......................................... 74 5.2 CATAWBA 18 OIESEL ENGINE INSPECTIONS............................ 74 5.2.1 PNL Evaluation........................................... 74 5.2.2 PNL Conclusions.......................................... 75 iii
I l
6.0. REVIEW 0F POST-INSPECTION TEST PLAN.................................. 76 6.1 OUKE POWER COMPANY POST-INSPECTION TEST PLAN.................... 76 5.2 EVALUATION...................................................... 77
6.3 CONCLUSION
S..................................................... 78 7.0 REVIEW 0F THE PROPOSED MAINTENANCE, INSPECTION, AND -
SURVEILLANCE PR0 GRAM................................................. 80 7.1 PNL EVALUATION.................................................. 81 7.1.1 Cylindar llaads..................................... .... 51 7.1.2 En gi ne B l ock and Base . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 7.1.3 Connecting Rods......................................... 85 7.1.4 Lube Oil Checks......................................... 86 7.1.5 Studs and Fixtures...................................... 87 7.1.6 Push Rods, Cams, Etc.................................... 88 7.1.7 Lube Oil Pressure 0 rop.................................. 88 7.1.8 Crankshaft Deflection Checks............................ 89 7.1.9 Moni tori ng Exhaust Temperatures . . . . . . . . . . . . . . . . . . . . . . . . . 90 7.1.10 Surveillance of Operating Parameters.................... 91 7.1.11 Other Inspection and Surveillance....................... 91 7.2 PNL CONCLUSIONS................................................. 93 8.0 OVERALL CONCLUSIONS.................................................. 94 8.1 GENERAL CONCLUSION.............................................. 94 4
8.2 LONG-TERM APPLICABILITY......................................... 94 8.3 KEY CONSIDERATIONS.............................................. 95 iv
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- A
-REVIEW AND EVALUATION OF TRANSAMERICA DELAVAL, INC., DIESEL ENGINE RELIABILITY AND OPERABILITY -
CATAWBA NUCLEAR-STATION UNIT 1 1
1.0 INTRODUCTION
I Duke Power Company (Duke) has requested an operating license for its Catawba Nuclear Station Unit 1 (Catawba). One key matter before the U.S.
Nuclear Regulatory Commission (NRC)-in considering tnis request is the >
operability and reliability (0/R) of the scation's standby emergency diesel-engine generators which have been brought into question by a number of circumstances (as described in Section 2.0). The subject engines were manufac- '
tured by Transamerica Delaval, Inc. (TDI).
To identify, evaluate, and correct these concerns, Duke has undertaken a number of industry-wide and plant-specific investigative, corrective. and administrative efforts. These have been addressed by Duke and its consultants in numerous documents and related meetings with NRC staff and NRC's consultant, Pacific Northwest Laboratory (PNL), PNL has been requested by NRC to review and evaluate these documents and Duke's underlying efforts and to prepare this technical evaluation report (TER) expressing its co,ncl'usions and recommendations.
Catawba Nuclear Station Unit 1 is served by two emergency standby engines to meet its ESF loads. Each engine is a - TDI OSRV-16-4 engine, nameplate rated by TDI at 7000 kW, operating at 450 rpm with a brake mean effective pressure (a computed measure of the average cylinder pressure in the firing stroke) of 225 psig. These engine-generators are designated by Duke as 1A and 18. The latest'information in the Final Safety Analysis Report (FSAR) specifies the emergency loads for these engines as a maximum of 5256 kW for a loss of coolant accident (LOCA) and a maximum of 5714 kW for a blackout or loss of offsite power (LOOP).
I 1
L.
1.1 SCOPE OF REPORT This TER is organized as follows:
2 Section 2.0 provides relevant background information on the known problems and efforts toward !*eir resolution by both Duke and an ad hoc group of similar TDI engine owners (the TDI Owners' Group) who have united their efforts in regard to these mutual concerns.
Section 3.0 presents a review and evaluation of specific problems experienced on the Catawba engines as well as of activities pertaining to the TDI Owners' Group generic components.
o Section 4.0 reviews Duke Power Company test and inspection activities on the 1A engine.
Section 5.0 reviews the activities Duke has conducted or plans to perform on the IB engine.
2 Section 6.0 documents PNL's evaluation of Duke's post-inspection engine tests.
s Section 7.0 presents PNL's review of the utility's proposed maintenance and surveillance (M/S) program. .
Finally, Section 8.0 presents PNL's overall conclusions and recommendations regarding the suitability of the two diesel engines to perform their intended function as emergency standby power sources for the-Catawba Nuclear Station Unit 1.
1.2 LIMITED APPLICABILITY OF CONCLUSIONS PNL has reviewed the basic documents referred to in Section 2.0, has participated in various meetings with Duke and NRC, and has observed components of both engines as disassembled in Duke's inspection program. Concurrently, PNL also has reviewed various relevant Owners' Group documents and participated in their meetings with NRC, and has completed TERs on some elements of tne Owners' Group Program Plan (0GPP). Because none of the various phases of the OGPP (as described in Section 2.1) has yet been finalized, PNL is not in a position to draw final conclusions on the overall extended operability and i
2
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reliability of these TDI engines in general, nor extensions thereof to plant-specific engines such as those installeo at Catawba.
This TER on the Catawba 1A and 1B engines' operability and reliability precedes completion of the OGPP and its appropriate implementation by Duke.
This document also precedes full plant-specific OR/QR analyses of both the 1A and IB engines. Therefore, PNL is constrained from reaching unlimited con-clusions relative to the Catawba 1A and IB engines' operability and reliability to perform indefinitely their expected design function. Any such conclusions, if supportive toward licensing, must necessarily be somewhat tentative, subject to full completion of all OGPP and Duke DR/QR programs and implementation of their findings (these actions should be a part of Duke's licensing authorization).
Hence, PNL has been constrained to evaluate all components in light of expected operating conditions and patterns at Catawba over a relatively short term.
The term chosen, thought by PNL's diesel consultants to be reliably conservative, was until the first reactor refueling outage, which PNL under-stands to be approximately 18 months from initial plant startup. By that time, all phases of both the general OGPP evaluation and implementation and the plant-specific Catawba DR/QR program should be complete or ready to imple-ment.
In PNL's judgment, .it would be more appropriate to decide long-term 0/R 4
\
at that time (near the first reactor refueling outage), rather than now.
The considerations and recommendations presented in this TER are sometimes expressed in~ terms of "until the first reactor refueling outage". However, in using this phrase, PNL does not intend to infer (unless specifically stated otherwise) that the engines or their components are therefore unreliable or inoperable for their intended use over their normally expected life.
1.3 REPORT PREPARATION This TER was prepared by the following PNL staff and consultants:
9 J. F. Nesbitt, PNL project staff 1
B. J. Kirkwood, Covenant Engineering, diesel consultant to PNL J. E. Horner, Seaworthy Systems, Inc., diesel consultants to PNL l 3
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1 P. J. Louzecky, Engineered Applications Corporation, diesel consultant to PNL.
Others whose contributions were considered in formulating the conclusions include PNL Assessment of Diesel Engine Reliability / Operability Project team members J. M. Alzheimer, M. Clement, S. D. Dahlgren, D. A. Dingee, R. E. Dodge, W. W. Laity, J. C. Spanner, and F. R. Zaloudek; and consultants S. H. Bush, A. J. Henriksen, and J. A. Webber (representing Ricardo Consulting Engineers plc).
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2.0 BACKGROUND
- This section presents background information on efforts undertaken by the TDI Diesel Generator Owners' Group and by Duke Power. Company to resolve the problems identified in the TDI diesel engines.
2.1 OWNERS' GROUP PROGRAM PLAN
- Thirteen nuclear utilities that own diesel generators manufactured 'by
, Transamerica Delaval, Inc. (TOI), have established an Owners' Graup to' address questions raised by a major failure in one TDI diesel engine (at tne Snarenam 5
Nuclear Power Station in August 1983), and other problems in TDI diesels reported in the nuclear and non-nuclear industry. On March 2, 1984, the i
Owners' Group submitted a plan to the U.S. Nuclear Regulatory Commission outlining a comprehensive program that included 1) an in-depth assessment of 16 known engine problems (Phase I), 2) a design review and quality revalidation.
(OR/QR) program that addresses other key engine components (Phase II), and
- 3) engine tests and inspections. A review of that submittal was conducted by
) PNL and reported to NRC in PNL-5161 dated June 1984 Section 4 of PNL-5161 deals with considerations for interim licensing of nuclear stations price to completion of the implementation of the Owners' Group Program Plan. Recommendattor.: in that report relevant to Duke Power Company's licensd for the Catawba Nuclear Station at this time are:
The engines should have AE pistons; if they do not, then " lead-engine" tests should be completed prior to licensing.
The diesel generators should not be required to carry a sustained j emergency load in excess of that corresponding to engine brake mean effective pressure (BMEP) of 185 psig, because, at that recommended limit, the maximum cylinder pressure is also approximately 1200 psig. The 6000-hour operating experience at Kodiak establishes a reasonable basis for confidence that AE piston skirts will operate satisfactorily at this load level. Also, pending evaluation and approval of Owners' Group reports addressing crankshaft stress levels I
at higher loads, the load corresponding to 185 psig BitEP is 5
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considered reasonably conservative for the crankshaft. In addition,
- because of certain open items in the implementation of the Owners' Group Program Plan, an Odequate basis does not yet exist to provide reasonable assurance that TDI diesel engines would operate reliably in. nuclear service at power levels higher than.those corresponding to a BMEP of 185 psig. Key engine components of particular concern in this regard include the piston skirts and the crankshaft, because their condition cannot be monitored without significant engine disassembly.
o The engines should be inspected to confirm that the components are 4
sound (see Sections 4 and 5).
o Preoperational testing should be performed (see Section 6).
1 The engines should receive enhanced surveillance and _ maintenance thereafter (see Section 7).
- 2.2 CATAWBA NUCLEAR STATION In their efforts to establish the reliability and operability of Catawba's TOI diesel engines, Duke Power Company has produced numerous letters and reports, as well as holding meetings and conducting tests, inspections, and examinations. Items pertinent to this Technical Evaluation Report are listed below.'
A letter dated February 17, 1984, to the Atomic Safety and Licensing Board Panel (ASLB), " Duke Power Company et al. (Catawba Nuclear Station, Units 1 and 2), Docket Nos. 50-413 and 50-414", noted problems with some components on the 1A engine at Catawba.
In a letter dated February 22, 1984, " Catawba Nuclear Station Docket
- Nos. 50-413 and 50-414", Duke Power Company transmitted their responses to 17 NRC questions regarding the TDI diesel generators
- installed at Catawba.
- A letter dated March 29, 1984, to the ASLB, " Duke Power Company et al. (Catawba Nuclear Station, Units 1 and 2), Docket Nos. 50-413 and i 6
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50-414", noted problems that had occurred with the 1A and 18 diesel engines.during the extended operational tests and the ESF test currently being conducted.
In an April 5,1984, letter to NRC, Duke provided a written description of the extended operational tests and inspection plans for the 1A diesel generator (engine) in addition to a discussion of Catawba-specific problems.
On April 26 and 27,1984, PNL staff and consultants visited Catawba to view the disassembly and inspection of the 1A c1esel engine and its components. A PNL letter dated May 7,1984, summarized comments and suggestions made to NRC pertaining to this visit. A report on the trip was submitted to NRC by PNL in a letter dated May 11, 1984 During the April 26 and 27 visit, the PNL observers recom-mended 100% (instead of 25%) inspection of AN pistons in 1A. Upon completing the full inspection, Duke personnel reported four AN piston skirts had indications. Subsequently, Duke decided to replace all AN piston skirts with the latest AE design.
On June 1, 1984, Duke provided a submittal to NRC addressing 76% of the 1A diesel engine inspection results.
i i
- On June 21, 1984, a meeting was held in Washington, D.C., at which Duke Power Company presented results of the 1A diesel engine inspect. ions to NRC and PNL.
- On June 22, 1984, PNL staff and consultants met with representatives of NRC at Failure Analysis Associates in Palo Alto, California, to discuss Owners' Group reports prepared by FaAA.
- A letter dated June 25, 1984, to the ASLB, " Duke Power Company et al.
f (Catawba Nuclear Station, Units 1 and 2) Docket Nos. 50-413 and 50-414", summarized the findings of the substantially completed 1A diesel engine inspection effort.
Via a letter to' NRC dated June 29, 1984, Duke Power Company
- transmitted the report, Catawba Nuclear Station Diesel Engine 1A Component Revalidation Inspection Final Report. This report 7.
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4 described the results of the inspections and evaluations performed and addressed over 99% of the inspection plan. Duke also indicated i
that all remaining inspections would be documented in the Owners' Group Phase II Program report.
NRC Generic Letter 84-15, dated July 2,1984, " Proposed Staff Actions t to Improve and Maintain Diesel Generator Reliability", was issued to
}
all licensees of operating reactors, applicants for an operating license, and holders of construction permits.
4 A letter to NRC dated July 5,1984, outlined Duke Power Company plans j ,
for the inspection of the Catawba 18 diesel engine and the return-i i
to-service testing of the 1A diesel engine.
s On July 10, 1984, two PNL consultants visited the Catawba Nuclear Station to view the status of the 1A diesel engine reassembly. '
In a letter dated July 16, 1984, Duke Power Company submitted its
} plans to NRC for the periodic maintenance, inspection, and i
surveillance of the Catawba 1A and 18 diesel engines.
A July 17, 1984, letter from Duke to C. Ray, Jr., of the TDI Owners' 3 Group detailed the operating history of the 1A and 18 diesels.
3 :
On July 25 and 26, 1984, PNL staff and consultants visited the Catawba Nuclear Station to view the disassembly and inspections being performed on the IB engine. The PNL team also observed the status of l
the reassembly of the 1A engine, and reviewed and discussed the findings noted and actions taken on specific engine components with Duke and NRC representatives. During the July 25 and 26 visit, the PNL observers queried various items, including the need to fully ,
inspect the link-pin bushings, and to take pre-turbine exhaust gas i
temperatures.
j ?
In an August 1, 1984, letter to NRC, Duke responded to concerns and queries raised by NRC and PNL in the July 25 and 26 meeting. '
i 8
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3.0 EVALUATION OF COMPONENT PROBLEM RESOLUTION Ouring the tests and inspections conducted by Duke Power Company on the l
Catawba Nuclear Station Unit I diesel engines, problems were noted or expe-rienced with certain engine components. The affected components included:
o piston skirts (a)
- push rods (a)
- cylinderhead(a) o fuel line fittings a fuel oil injcetion pump valve holders
- turbocharger (a) bearings e turbocharger adapter
- turbocharger lube oil drain line
- turbocharger prelube oil lines 2 turbocharger exhaust gas inlet bolts 2
crankcase and camshaft cover capscrews
- triple-clamp bolts o
lube oil and jacket water thermocouples i
rocker box (subcover) assembly 5
intermediate rocker arm sockets i
exhaust valve tappets (rocker arm adjusting sc,rew swivel pad) s intake and exhaust valves
- spring , retaining nut and roll pin on air start valves.
Section 3.1 documents PNL's evaluation of the actions taken by Duke Power Company to resolve known problems with these diesel engine components. The information on these components is presented in a worksheet format. Each worksheet identifies the component, briefly reviews its history, and describes the status of, or the actions taken by the Owners' Group and Duke to evaluate or resolve, the problem. The last item on each worksheet presents PNL's evaluative comments and/or conclusion :.
(a) TDI engine generic problem components.
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l Section 3.2 documents the actions taken by Duke regarding the engine components classified in the generic problem category by the TDI Owners' Group. -These components include:
- crankshaft a
connecting rod bearing shells
- cylinder blocks
- cylinder liner o cylinder head studs 3 engine base and bearing caps e rocker arm capscrews e connecting rods
- engine mounted electrical cable S
high-pressure fuel tubing
- jacket water pumps 2 air start valve capscrews.
Although Duke has not experienced any specific failures with these components at Catawba, they are nevertheless documented here for completeness, also in a worksheet format. Each worksheet for these items includes a brief history of the component, a review of actions taken by the Owners' Group to evaluate the problem, a description of the tests, inspections, or evaluations performed on these components at Catawba, and PNL's evaluative comments and/or conclusions.
PNL's conclusions and comments are based on the available Duke Power Company documents, on onsite inspections of the Catawba engine components and examinations of identical or at least similar components of TOI diesels in ,
other nuclear facilities, reviews of the specific known-problem issue reports prepared by (or under the auspices of) the TDI Owners' Group, and the experienced judgment and appropriate evaluations of PNL's diesel engine consultants. However, pending completion of the implementation of tne Owners' Group Program Plan, PNL's conclusions as stated in this report are plant-specific, applying only to Duke Power Company's Catawba Nuclear Station Uni
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3.1 PLANT-SPECIFIC PROBLEMS Component: Piston Skirts Part No.: 02-341 Owners' Group Report: FaAA-84-2-14 Brief History of Component-Based on a number of cracks found in the AF piston skirts at the Grand Gulf Nuclear Station, the Shoreham Nuclear Power Station, and at non-nuclear i installations, the skirt design was strengthened in the boss area where the i cracks had been found. No operational failures have been reported to date on the redesigned piston skirt, labeled AE, in either nuclear or non-nuclear installations. Kodiak (an electrical generation station) has operated in excess of 6000 hours0.0694 days <br />1.667 hours <br />0.00992 weeks <br />0.00228 months <br /> at approximately 185 psig BMEP (1200 psig maximum firing pressure) with the AE skirts; the TDI R-5 test. engine has operated in excess of l 600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br /> with a maximum firing pressure of 2000 psig and BMEP of 275 psig with a slightly modified AE skirt design.
Another type of piston skirt labeled AN is in wide use according to TOI.
1 4 Only Catawba, of all of the nuclear plants, had AN piston skirts. TDI has
.: indicated that the AN piston skirts, if properly heat-treated, have performed l
1 satisfactorily.
Owners' Group Status i
- . Piston ' skirts have been identified by the TDI Owners' Group as one of t.ne generic problem components. . The Owners' Group consultant, Failure Analysis Associates (FaAA), has analyzed the AE piston skirt design and has concluded that the AE skirts may crack at 10% overload of nameplate rating, but that cracks will not propagate to the point of actual functional failure. Cracks have been found to occur in the vicinity of a structural rib and bolting boss inside the skirt.
l The issue of AE piston skirts was addressed by PNL in its June 1984 Review and Evaluation of TOI Diesel Generator Owners' Group Program Plan (PNL-5161),
Section 4.0, relative to nuclear plants seeking interim licensing (prior to finalization and full implementation of the OGPP). Therein it was concluded t 11 c
l
that plants with AE piston skirts having sustained emergency load requirements not exceeding 185 psig BMEP cduld logically and safely be licensed without prior lead-plant testing to 10 million cycles (750 hcurs) at or above this load.
Duke Power Company Status During the extended operational test, the 1A diesel was operated with AN piston skirts that.had been heat-treated at the TOI factory. During cne subsequent disassembly and inspection, cracks were found in 4 of the 16 piston skirts.
The inspections of AN piston skirts conducted by Ouke Power Company were directed at assessing these components' structural integrity. All 16 piston skirts on the 1A engine were subjected to the following inspections:
o visual inspection 1
liquid penetrant examination of stud bosses liquid penetrant examination of piston pin bosses liquid penetrant or magnetic particle examination of areas adjacent to the piston pin bosses (i.e., the areas where several cracks were noted) e ultrasonic and radiographic examinations if I Nuid penetrant or magnetic particle examinations revealed indications.
The mos't significant condition noted during the inspections conducted at Catawba was the presence of cracks adjacent to piston pin bosses in four piston skirts. As reported by Duke, the largest crack was 3 or 4 inches long and penetrated through the wall. The cracks appeared to originate at the skirt ID, on the fillets where a reinforcing rib intersects the piston pin bosses, and to run in an approximately axial direction. The cause of the cracking is undeter-mined at this time but is believed to be high-frequency cyclic fatigue. One small (1/2-inch long) linear indicauon was also noted in the bore of a piston pin boss.
No indications were found at stud bosses.
The AN piston skirts from the 1A diesel at Catawba have been sent to FaAA for a detailed failure analysis as a part of the TOI Owners' Group Program.
12 I
l Duke Power Company has reported its intention to replace the AN piston skirts with type AE skirts. This has been done on the 1A diesel engine and is in progress on the 18 engine. PNL understands that Duke either has performed or will perform surface nondestructive examination (primarily magnetic particle tests) and hardness tests on the AE piston skirts prior to their installation in an engine to verify their acceptability.
PNL Conclusions Upon completion of reassembly of engine 18, both Catawba diesels will be fully fitted with AE piston skirts. The Catawba emergency load requirements, listed in Section 1.0, do not exceed interi;n-licensing recommendations of PNL-5161 (referred to above). Based on this knowledge, on all available analytical information (principally the OG generic issue report, FaAA-84-2-14),
the operational history of AE skirts, the test results on AE skirts elsewhere, and the judgment of its diesel consultants, PNL concludes that the AE piston skirts are suitable for the intended use in the Catawba 1A and 18 engines, at least until the time of the first reactor refueling outage.(a)
(a) This conclusion, cad similar conclusions regarding other components, :;
based upon the assumption that NRC and the Owners' Group will satis-factorily resolve concerns regarding the component and implement all requirements (see Section 1.2).
13
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Component: Push Rods Part No.: 02-390-C Owners' Group Repo-t: FaAA 84-3-17 Brief History of Component The push rods originally had tubular steel bodies fitted with hardened steel end pieces attached with plug welds. An estimated 2% reportedly developed cracks in or around the plug welds. A push rod design introduced a later consisted of a tubular steel body with a carbon steel ball fillet welded to each end. This design proved to be prone to cracking at the weld. A third push rod design, consisting of a tubular steel body friction-welded on each end to a forged plug with a machined hemispherical shape, was then introduced.
This third configuration is referred to as the friction-welded design.
Owners' Group Status Because industry (both nuclear and non-nuclear) had expressed substantial concern about the continued integrity of TDI push rods, the TDI Owners' Group included the component in the known generic problem category for specific study and resolution. Failure Analysis Associates has performed stress analyses as well as cycle wear tests to 10 million cycles on a sample of the friction-welded push rods at conditions simulating full engine nameplate loading. No sign of abnormal wear or deterioration of the welded joints was observed.
Duke Power Comoany Status The push rods supplied as the original components of the Catawba lA and 18 diesels experienced cracking in the plug welds joining the center to the end sections. However, these failures did not prevent the push rods from performing their intended functions, nor did they result in any abnormal or adverse engine performance. During the week of February 5,1984, all of the push rods in engine 1A were replaced with those of the friction-welded design. In the subsequent extended operational tests, about 400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br /> of operation were accumulated on this set of friction-welded push rods prior to the disassembly and inspection of the 1A engine. This set of friction-welded push rods was then removed from the 1A engine and installed in the 18 diesel 14 t
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i engine at Catawba.
According to Duke Power Company personnel, this set of push rods has now been in operation for over 900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br />, with at least one-half of that time being at engine loads above 185 psig BMEP.
The Duke Power Company inspections of the friction-welded design push rods
.in the 1A engine included:
visual inspection of the shaft end-welds to verify that the desired new type of friction welds were used S
liquid penetrant examination of all welds.
Duke Power Company reported their confirmation that all the push rods in the 1A engine had the correct type of end-welds and were free of defects.
Duke is performing visual and surface nondestructive examinations on this same set of push rods after its extended service in the 18 diesel engine. This examination is still underway, but Duke personnel indicated to PNL representatives during the Catawba site visit on July 25 and 26,1984, that no defects had yet been found.
PNL Conclusions After reviewing the FaAA report, the Catawba inspection data, and examin-f ng some of the friction-welded push rods at Catawba on July 25, 1984, PNL concludes that the push rods incorporating the friction-welded design are satisfa,ctory for their intended purpose, until at Idast the time of the first reactor refueling outage.
15
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..*,o Component: Cylinder Heads part No.: 02-360A Owners' Group Report: FaAA-84-15-12 Brief History of Component Numerous repcrts on TDI cast steel cylinder head failures are available from both the nuclear and non-nuclear industry. For identification purpnsas, TDI cylinder heads are classified as I', II and III, all under the same part number.
Group I heads include those cast prior to October 1978; Group II heads are those cast between October 1978 and September 1980; and Group III comprises heads cast after September 1980. Most instances of cracked heads have involved Group I.
Only five instances of water leaks in Group II and III neads have been reported, all in marine applications. Most of the reported cracks initiated at the stellite valve seats.
The most recent, known head failure was reported by Mississippi power &
Light relevant to their Division I T0! diesel engine (letter to NRC dated July 30, 1984, AECM 84/0401). It reported a 2-inch through-wall crack in the right exhaust port casting surface between the valve seat area and the exhaust valve guide (head 7L). It allowed jacket water to penetrate from the head cooling passages into the cylinder cavity, and was detected by barring-over the engine with cylinder cocks open. The specific head. group classification of this head was not reported. However, the affected head was an original that had undergone 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> of operation. Of this total, approximately 335 operating hours were at 100% load (7000 kW, 225 psig BMEP) and 31 hours3.587963e-4 days <br />0.00861 hours <br />5.125661e-5 weeks <br />1.17955e-5 months <br /> were at 110% load.
This failure is still undergoing investigation; however, because no similar failure has occurred to MP&L's knowledge, it concludes tnis was a unique, isolated failure.
Owners' Group Status The cylinder heads are included in the TOI Owners' Group generic problem l
category. Failure Analysis Associates' mechanical and thermal stress calcu-
' lations, which did not include finite element calculations, concluded that Group I, II, and !!! heads as designed are adequate for the service intended.
The report recommends that Group I and II heads be inspected by liquid 4
16
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penetrant and magnetic particle, as well as ditrasonic, testing to determine firedeck thickness. For Group III heads, sample inspection as described above ;
}
is recommended. For all three groups of heads, FaAA recommended barring the engine over before manual startup, to assure no water has leaked into the cylinders.
Cylinder heads are also included in the TDI Owners' Group design review /
l, quality revalidation (DR/QR) program. The first such program report, pertain-ing to tne Snorenam Nuclear power Station, has just been released. In that j report, the Owners' Group has concluded that the cylinder heads are acceptable for their intended design function at Shoreham, provided that engine barring-over is conducted.
(
Ouke Power Company Status Two small Jacket water leaks have been experienced in heads at Catawba, one each in engines 1A and 18. As a result, water leaked into the fuel injector nozzle cavity (i.e., external to the head and cylinder). Failure Analysis Associates performed a metallurgical analysis of the leak that occurred on the 1A engine. FaAA reported that the leak was due to cracks i
propagating from a corner where a repair plug was welded into the fuel injector
) nozzle seating area. This welded plug had been installed by TOI during manu-
) facture to repair the injector bore.
l As stated by Duke power Company in their inspe'ction report dated June 29, T
[
i 1984, the inspections of the 1A engine cylinder heads included:
j e liquid penetrant examination of valve seats in cylinder heads S
l ultrasonic examination of firedeck thickness at selected locations.
- Duke has stated that no other cracks were detected and that all firedeck j
thicknesses of cylinder heads on the 1A engine were found to be acceptable.
Duke power Company performed an engineering evaluation to determine if any j
of the heads now installed on the 1A diesel engine had been repaired during
- manuf acturing. A borescope was used to show whether there was a parting line j
at the bottom of the fuel injector cavity, indicating the presence of a plug. ,
In addition, visual inspection of the firedeck area of the head was used to l check for the presence of weld metal, indicating a plug was installed.
i i 17 i
i According to Duke, the results of this engineering evaluation indicate that the head installed on the no. 6 cylinder in the left bank was repaired with a welded plug. This head (6L) had been factory-installed on the engine and has seen over 800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br />' operation at varying loads, with at least one-half of that i time being at loads in excess of 185 psig BMEP.
- Duke has reported that, in its opinion, the cylinder heads currently installed in the 1A diesel engine are satisfactory because they were not
! leaking when last used, and because they exht::it rc cracks in inspectable areas. Further, the leaks caused by cracks due to plug-welding are only to areas external to the head and cylinder, do not affect diesel operation, and are not significant. However, the repaired head (6L) is to be replaced as soon as Duke can obtain a replacement that does not contain similar weld plugs.
, The same examinations are to be performed on the IB engine cylinder heads.
PNL Conclusions r
! PNL has reviewed all the pertinent documentation noted above: the F4AA
) report, TDI Owners' Group OR/QR report on the Shoreham plant, and the Duke
{ inspection report. In addition, PNL has reviewed the engine inspection results
~
, onsite with Duke Power Company. On these bases, PNL conc 1udes that the cylinder heads on the Catawba 1A diesel engine are acceptable for the first refueling cycle, provided that the engine is barred-over 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after shutdown, then again 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> af ter shutdown, and t9tereafter prior to each j planned start, to check for water leakage into the cylinders.
I PNL also concludes that Duke should replace the 6L nead on the 1A engine,
[
as well as any of the cylinder heads on the 18 engine that have repair plugs installed. '
Based in the assumption that the results of tests and inspections on the IB cylinder heads will be positive, that Duke has reported only satisfactory operation during the extended tests, and that the 1B engine will be barred-over as was the 1A engine, PNL concludes that the heads on the IB engine will be acceptable for their intended purpose through at least the first refueling cycle.
K 18 0
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- . .* a Until the generic-issue analysis on heads has been finalized and a tech-nical evaluation report has been released indicating satisfactory conclusion of the issue, PNL cannot grant unreserved approval of the heads, regardless of their manufacturing group classification (I, II, or III).
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19
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Component: Fuel Line Fittings Part No.: 02-4508 Brief History of Component A low-pressure fuel line between two fittings failed at the Grand Gulf Nuclear Station. Mississippi Power & Light, the owner utility, concluded that this isolated failure was due to fatigue caused by vibration due tu insuffi-cient clamping. One low-pressure fuel line was replaced on the Catawba 1A diesel engine because of leakage. Inspection of this line indicated its fit-tings were not swaged properly. Duke Power Company reported that the leakage resulted after a flat spot in the cone section of the tube eroded away. No similar failure has been noted on the 1B engine.
Owners' Group Status The TDI Owners' Group has included fuel line fittings in the ongoing OR/QR program. The just-released OR/QR report on the Shoreham Nuclear Power Station concluded that, with stipulated modifications to meet design requirements, the <
equivalent fuel oil headers-piping and tubing will meet the stress and support design criteria and will perform their intended design function under all normal and earthquake loadings.
Duke Power Company Status Most of the fuel lines and fittings were disconnected during the recent disassembly and inspection.
They will be reinstalled during the reassembly of the 1A diesel engine. Duke Power Company has announced its intention to follow specific fitting installation instructions during the reassembly process to guard against improper swaging. In addition, after the 1A engine is reas-sembled, Duke personnel will inspect the subject lines and fittings. This will include a walkdown inspection to verify that the piping has been installed according to the applicable design drawings.
PNL Conclusiuns The Duke Power Company fitting installation instructions and inspection procedure were discussed during PNL's visit to the Catawba Nuclear Station on July 26, 1984 PNL concurs with Duke's analysis of, and actions taken to l
20
. l
. o "
correct, the problem. PNL also concurs that reinstallation of the fuel lines and fittings on the Catawba 1A diesel engine, if conducted accoroing to the planned procedure, should be sufficient to assure that they will perform their intended functions. This problem and its resolution appear to be specific to the 1A engine only.
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l Component: Fuel Oil Injection Pumo Valve Holder Part No.: 02-365-A Brief History of Component Minor failures of fuel oil injection pump components have be*9 recorded at the Grand Gulf Nuclear Station.
Owners' Group Status This component is included in the TDI Owners' Group OR/QR Program. In the recent OR/QR report for the Shoreham Nuclear Power Station, it was concluded that the pump is acceptable for its intended design function at Shoreham. The report also stated that "A review of the operating history of the Bendix fuel injection pumps at Shoreham and other n'uclear power plants indicates that any leaks that occurred were attributed to loose connections, fittings and bleed screws, etc., and not to the primary pressure boundary."
Duke Power Company Status A fuel injection pump valve holder, which is exposed to full discharge pressure, fractured on the Catawba 1A engine. Duke Power Company submitted the part to Babcock & Wilcox Alliance Research Center for examination. Babcock &
Wilcox concluded that the fracture initiated at a casting defect in the part, and that it was not the result of a design deficieifcy.
Transamerica Delaval, Inc., reported to NRC on July 13, 1984, that Bendix Corporation (the fuel injection pump manufacturer) had reviewed the component failure at Catawba and indicated the cause to be a material defect in the valve holder. Further, in Bendix's opinion, this defect was an isolated case. TOI stated that Bendix high-pressure fuel injection pumps have been installed on all OSR and OSRV engines manufactured by TOI in the past 15 years and that the Catawba holder failure is the first and only one of this type of which they are aware.
In addition to Babcock & Wilcox's detailed examination of the one failed valve holder, related inspections performed on the 1A engine to date by Duke Power Company include:
22
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r measuring the hardness of each valve holder ultrasonic testing of each fuel pump valve holder.
Duke has reported that, based on the inspections conducted, all . fuel pump valve
. holders on the 1A engine were found to be acceptable.
3 Duke also performed a failure analysis on the fractured fuel injection 2
pump nozzle valve holder. The results of this analysis indicated that an axially-oriented linear indication in the high-pressure fuel oil passage of the valve holder led to the reported failure. Further analysis revealed that axial linear indications that would lead to cracking of the valve holder could cause
} cracking to occur within 10 million cycles of fuel pump operation. Because the remaining valve holders on the Catawba 1A diesel engine have withstood j
10 million cycles of operation, the valve holder failure experience is considered the result of gn isolated material defect.
In addition to this analysis, a borescope evaluation of the high-pressure fuel oil passage was made. Results of this evaluation indicate that several of the valve holder bores were rough-machined, as evidenced by observed protru- f,
,k.'
sions, counterbore type steps, and tool marks. One valve holder, cylinder 6R, -
4 appeared to have a linear indication. Three valve holders (SR, IL, and 8L) had recesses.
l Duke has stated that these four valve holders will be removed from ,.
the engine, cleaned, rechecked by borescope, and reamed if-indications are
{ still present after cleaning. Valve holders that have indications after reaming will be replaced.
pNL Conclusions
- A failure of this specific pump component will tend to reduce engine capacity by 7% and imbalance the load on the crankshaft, but will not lead to immediate shutdown. Based on the results of examinations and analyses per-formed by Duke power Company, as well as an examination by pNL during the Catawba site visit on July 25 and 26, 1984, PNL concurs with Duke's analyses of, and actions taken to correct, the problem. pNL concludes that the fuel injection pumps as now installed on Catawba's 1A engine will perform their intended design functions. This problem and its resolution appear to be a one-
! time occurrence, limited to the 1A engine only. '
23 i
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Component: Turbocharger Bearings part No.: MP-022/23; 02-CFR Owners' Group Report: FaAA-84-5-7 N .
Brief History'of Component c -
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Turbocharger thrust bearing problems reportedly are limited to the nuclear industry; .To date, thrust bearing problems have been reported for the Grand
.Culf Nuclear Station, Shoreham Nuclear power Station, San Onofre Nuclear Generating Stati,on, Coma 5che Peak Steam Electric Station, and Catawoa Nuclear Station. h Owners' Group Status The TDI Owners' Group has included turbochargers in general in the generic problem category, Failure Analysis Associates analyzed the turbocharger thrust bearing problems for the Elliott 90G turbocharger. In Report FaAA-84-5-7 dated May 1984, FaAA concluded that 'the problems are due to insufficient lubrication of the thrust bearings during " fast" starts (i.e., automatic starts for which no prelubrication is provided to the thrust bearing). Various types of startup lubrication systems have been implemented at nuclear power plants to avoid these problems. One type is a drip system that provides lubrication from the before-and-after (B&A) recirculation system. Another type (in use at the Grand Gulf Nuclear Station) is an auxiliary B&A lube oil pump. This pump is acti-vated prior to any planned start and provides the turbocharger bearings with sufficieni lube oil to complece fast starts as required for nuclear standby tests. -
Ouke Power Company Status On February 17, 1984, Duke' Power Company reported finding excessive wear on ,a bearing in one turbocharger of engine 1A. As Duke reported later, on March 29, 1984, the thrust faces of bearings were found to be severely worn in
' 'curbochargers irl .both 1A and IB engines.
' Duke persoEnel[perfomed visual and dimensional inspections of the 1A engine turbocharger beaEings. The thrust faces were found to be severely worn.
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l However, Duke noted that this wear had not affected turbocharger operation during the extended (>800 hours) operational tests on the 1A engine. Similar inspections of turbocharger bearings on the 18 engine are.in progress.
The turbocharger bearings on the 1A engine were replaced. In Duke's opidion, these will operate as well as the original bearings, which caused no operational problems for several hundred hours. In addition, in a June 29, 1984, letter to NRC, Duke has stated its intention to install the new increased flow lube oil system 'yuSeptember 1984 Until that time, Duke plans to inspect the new beirings periodically to assure their continuing operability.
PNL Conclusions PNL and its consultants have not had an opportunity to review the specific prelude system design planned by Duke for the Catawba engines. However, PNL has reviewed the FaAA report referenced above, the results of the June 22, 1984, meeting among representatives of FaAA, the Owners' Group, NRC, and PNL,.
and the inspection data presented by Duke Power Company. During the Catawba site visit on July 25 and 26, 1984, PNL examined the IB engine turbocharger bearings, which, like those from engine 1A, were scarred and substantially worn. PNL also has examined the prelube system at other, similar plants. On these bases, PNL concludes that a similar new prelube system planned for installation on the diesels at Catawba probably will provide sufficient additional lubrication to augment the protection of the turbocharger bearings during planngd fast starts. Further, in PNL's view, the number of unplanned fast starts, without prelube, likely will be sufficiently few as to not lead to bearing failure prior to the first refueling outage, at which time the bearings on at least one turbocharger per engine should be reinspected (unless, by that time, the revised turbacharger prelube system has been installed and accepted by the Owners' Group and NRC).
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P' Component: Turbocharger Adapters Ptip No.: 00-495A s
Duke Power Company Status At Catawba, one turbocharger adapter on the 1A diesel cracked at a flange weld. This. adapter provides the interface between the turbocharger air dis-charge and the intercooler airbox. Duke Power Company has attributed the crack to poor flange. alignment with mismatched bolt holes.- Duke reports it now uses updated alignment practices when installing the adapters and torquing turbo-charger fin.ge bolts. Duke has reported that the weld joints on the 1A diesel engine turbocharger adapters were examined visually and with magnetic particle detection techniques. These examinations revealed no defects.
During PNL's Catawba site visit in July 1984, Duke personnel reported having obtained TDI's concurrence to overbore the mounting holes'and use an alternative gasketing arrangement. It is PNL's understanding that this was done on the right bank of the 18 diesel engine, which was found to be cracked in a manner comparable to that of the 1A right bank. No problems have been noted on the left bank of either engine, which is of a configuration different from that of the right bank.
According to Duke personnel, they and TOI are,considering improved con-figurations for the right bank interface that will assure the elimination of l
this problem,. These may require making a number of changes on the engines.
PNL Conclusions PNL concludes that Duke has adequately identified the problem and its cause.
However, in reviewing the Duke Power Company information available on the turbocharger adapter flange and the noting of the subsequent crack on the IB diesel engine, PNL has found no evidence to support a conclusion that an adequate corrective method has been implemented. In the opinion of PNL's consultants, the Catawba diesels could be relied on for satisfactory operation for a period of time, possibly up to sparal days, even with cracks in the welds at this adapter, although some power reduction and imbalance between left and right cylinder banks could result. Thus, these adapters and the entire 26
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turbocharger /intercooler interface are considered to be marginally suitable for their intended use in the Catawba IA and IB engines ~ even until the first reactor refueling outage. Therefore, PNL recommends that Duke /TDI continue with the development of an alternative design for the right bank connections between the turbocharger and the intercooler and, further, that adapters of a new design be installed. '
It is believed by PNL and its consultants that the alternative connection design being considered or developed by Duke /TDI should be one incorporating a flexible joint. Such a design is deemed to be one that could eliminate the problem and have an adequate operating life.
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Component: Turbocharger Lube Oil Drain'Line Part No.: 02-467A Brief History of Component Duke Power Company reported that a temporary drain line on the 1A diesel engine leaked during the recent extended operational test. The leak was attributed to vibration in the drain line. This drain line was of rubber hose, installed in place of the original compression-coupling fitting furnished by TDI, which, for some unexplained reason, would not fit properly at installa-tion.
The installation on the 1B engine reportedly was as per the TDI design.
Owners' Group Status The TDI Owners' Group Program Plan indicates that the turbocharger lube oil drain line is included in the ongoing OR/QR program. In the DR/QR report on the Shoreham Nuclear Power Station on the equivalent component, it was concluded that, when installed and supported in accordance with TDI design, the small-bore piping and tubing included in the review meets the stress design criteria and will perform its intended design function at Shoreham under all
, normal and earthquake loadings.
Duke Power Company Status The leaking 1A engine drain line was replaced with the proper line and fittings during reassembly of the 1A diesel engine. During the July 25 and 26 Catawba site visit, Duke personnel stated that the line now installed on the 1A engine meets the TDI design requirements.
PNL Conclusions PNL concludes that Duke has appropriately identified the problem and its cause.
PNL representattaves examined the lube oil drain line during the Catawba site visit on July 25 and 26, 1984 They noted that the subject line on the 1A diesel engine now contains only welded or clamped joints. Based on these observations, PNL concludes that the new drain lines as now installed on the Catawba diesels will satisfactorily perform the intended design function.
This problem and its resolution appear to be specific to the 1A engine only.
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. Component: Turbocharger Prelube Oil Lines Part No.: 02-307B Brief History of Coraponent:
Two failures of prelube oil lines were reported by Duke Power Company.
Both failures occurred on.the 1A engine during the extended operational test.
Owners' Group Status The turbocharger prelube oil lines are included as part of the Owners' Group DR/QR Program. In the DR/QR report on the Shoreham Nuclear Power Station, the conclusion on the equivalent components was as follows:
4 The tubing components, as defined by this component design review have been evaluated to the referenced stress design criteria and found acceptable. It is concluded that the system will perform its intended design function at Shoreham under all normal and earthquake loadings.
Duke Power Company Status Duke personnel performed visual, chemical, and metallographic tests on the failed components. Based on the test results, they reported the probable failure mechanism of the tubes was high-cycle fatigue that originated at stress concentrations produced in the area of the compression fittings.
Duke subsequently replaced the failed lines with heavier wall stainless steel tubings and improved compression fittings. These were installed using an improved pro'cedure, additional clamps, and vibrational dampening devices. No failures have since occurred.
Duke has stated its plans to reassemble and install the piping on the 1A diesel engine in accordance with the latest approval drawings and procedures.
In addition, the system will be inspected after reassembly to verify proper installation.
PNL Conclusions PNL concludes that Duke has adequately identified the problem and its cause, and has responded appropriately. During PNL's onsite visit in July i 1984,'it was noted that the turbocharger prelube cil lines will be replaced 29
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with ones of a different design when the new turbocharger lubrication system is installed on the Catawba engines. In PNL's opinion, lines and fittings installed in a manner similar to those installed after the original failures will adequately fulfill their intended purposes. No comment, evaluations, or conclusions on the redesigned system can be made at this time.
PNL assumes that Duke will follow the improved procedures and use the same additional and improved material on the subject lines of the 1B engine as they did on the 1A engine. If so, PNL concludes that the subject items on the IB engine would also fulfill their intended purposes.
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Component: Turbocharger Exhaust Gas Inlet Bolts Part No.: 02-3808 Brief History of Component Duke Power Company has reported the failure of four 1/2-inch diameter turbocharger e.xhaust gas inlet bolts on the 1A engine.
Owners' Group Status These components are also included in the TOI Diesel Generator Owners' Group DR/QR Program. The Shoreham Nuclear Power Station OR/QR report concludes that, based on new bolting materials and revised installation procedures, the exhaust manifold components are acceptable for the intended service and design function at Shoreham.
Duke Power Company Status The failed bolts were examined by Duke Power Company's Physical-Sciences Laboratory. They concluded that the bolt failures were caused by bonding of the bolt threads to the adapter flange during service at high temperature, necessitating the application of excessive force to remove the bolts e
creep rupture due to a combination of a) use of lubricant plus applied torques leading to high axial stresses'(easily over 25,000 psi and possibly as high as 75,000 psi); b) high temperature; and c) use of an alloy not resistant to creep.
The original 36 bolts, which had been exposed to over 800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> of operation, and the four replacement bolts were inspected visually at SX magni fication. Duke reported that no defects or indications were found on any of these bolts.
Duke has announced their intention to replace all of the subject bolts on the 1A diesel with others of the same material, using installation procedures to assure the application of proper preloads. In addition, new bolts made of a creep-resistant material are being considered as replacements for those currently installed.
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PNL Conclusions
- During the PNL onsite visit on July 25 and 26,1984, Duke personnel t
reiterated their application and use of torque criteria on essentially all fasteners of the Catawba diesel engines. PNL concludes that Duke has adequately identified the problem and its cause and has proceeded with an accepta'ble resolution. In PNL's opinion, the turbocharger exhaust gas inlet bolts will satisfactorily perform their intended function over their expected service life, provided that procedures which Duke has agreed to use are employed to prevent both under- and overtorquing.
It is PNL's understanding that Duke plans to replace the subject bolts on the IB engine. If so, and if this is done following the procedures used on the 1A engine, PNL concludes that the subject components will adequately perform their intended function.
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! Component:
Crankcase and Camshaft Cover Caoscrews Part No.: 02-3868 Brief History of Component Duke Power Company reported occasional failure of crankcase and camshaft cover capscrews at Catawba dQring the extended operational tests and as found during inspections of the 1A diesel engine. These failures were random and usually occurred as the bolts were being tightened to seal minor oil leaks or as the bolts were being removed. In a few instances, the bolt heads separated while the diesel was operating.
Duke Power Company Status Based on their examinations of the failed components, Duke has concluded that the capscrews failed due to fatigue caused by over- or undertorquing during installation on the 1A engine. Duke has also reported confidence that the problem has been resolved by replacing the failed components with capscrews of more appropriate quality and by revising installation procedures to control torque.
PNL Conclusions PNL reviewed the capscrew problem with Duke during the Catawba site visit in July 1984 PNL concludes that Duke has adequattiy identified the problem and its cause, and that the use of higher strength and higher fatigue endurance limit items le.g., Grade 5) installed within torque values established by TDI/ Duke for that installation and that size item should eliminate any future failures. Thus, the capscrews as now installed on the 1A diesel at Catawba should satisfy the intended design requirements.
Provided that Duke replaces the subject components on the IB engine with higher strength items under controlled torquing procedures, these capscrews too.
should satisfy the intended design requirements.
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Component: Triple-Clamp Bolts part No.: 02-4500 1
Brief History of Component The triple clamps support various types of piping lines along the top side of the engine. During the extended operational tests and the subsequent dis-assembly of the 1A diesel engine at Catawba, Duke power Company found that several of the triple-clamp bolts had failed in service. These failures occurred in the threaded portion of the bolt inline where the first threads engaged the subcover assembly.
Duke Power Company Status Duke subjected the failed bolts to a failure analysis. The results indi-cated that the bolts failed because of fatigue and being under- or overtorqued.
Duke indicated that all triple-clamp bolts were replaced with new bolts having higher strength and higher fatigue endurance limits (e.g., Grade 8). In addi-tion, reinstallation procedures now include provisions to assure that under-and overtorquing do not occur.
PNL Conclusions During the Catawba site visit on July 25 and 26,1984, PNL personnel and consultants discussed Duke's review of the triple-cJacy bolts, their replace-i ments,'and torque limitations. PNL concludes that Duke has adequately identi-i fied the problem and its cause and that the actions implemented should elimi-
) nate the recurrence of similar failures of the subject components. Thus, the colts as eventually installed in the diesels at Catawba should satisfy the intended design requirements.
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Component: Lube Oil and Jacket Water Thermocouples Part No.: 02-6300 Brief History of-Component Inconsistent or improper indications of operating conditions have been experienced with some thermocouples (T/Cs) at Catawba. According to Duke personnel, when these T/Cs were replaced, the indications of the operating conditions returned to the normal or expected operating range. Duke personnel have stated that these inconsistencies (or failures to indicate properly) were believed to be the result of intermittent shorts.
Owners' Group Status The Owners' Group OR/QR Program report for the Shoreham Nuclear Power Station concluded that the pyrometer conduit assembly thermocouples are acceptable for their intended design function at'Shoreham, provided 1) each T/C indicated temperature is consistent with the engine ambient temperature when the engine is cold and 2) the T/C is removed, cleaned, and inspected for fatigue indications every 36 months.
Duke Power Company Status Duke Power Company stated that occasional T/C failures can be expected and do occur.
Duke further stated that failure of the lube oil and water thermo-couples' would not affect diesel engine operability under emergency-run condi-tions. Duke-has reported that the failed T/Cs were repaired or replaced and that inspection of the failed T/Cs was not considered useful.
PNL Conclusions PNL discussed the failed T/C problem and operating history with Duke personnel during the Catawba site visit in July 1984 PNL concurs with Duke's analysis, i.e., T/C failures are an expectable occurrence, particularly during the early stages of equipment or system startup and operation. In PNL's opinion, occasional operating inconsistencies cr failures of the subject T/Cs can be expected to occur during the life of the diesel engine. However, i f such a failure does occur, it will not likely compromise the continued safe and 35
j reliable operation of the diesel engine. Therefore, PNL believes the correc-tive actions taken by Duke to be logical and supportable, and should be con-tinued as required by subsequent failures in the subject components.
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Component: Rocker Box (Subcover) Assemblies Part No.: 02-362A Brief History of Component Two different problems have been experienced with the rocker box (subcover) assembly on the 1A diesel engine at Catawba. The first reported by Duke involves the fracturing off of a piece of a boss located an the inside of the unit (also identified as rocker arm pedestal). The second problem, found in the post-operational test inspections of the 1A diesel, consists of hairline fractures running down the boss in the web between the machined bolt hole and the boss surface.
Owners' Group Status The subject component is included in the DR/QR program. The DR/QR review for the Shoreham Nuclear Power Station concluded that the subcover is acceptable for its intended design function at Shoreham.
Duke Power Company Status Duka Power Company reported finding one subcover with a piece of a boss ,
fractured off wnen the push rods were replaced. However, Duke noted that this situation had not adversely affected the engine's operation.
After the extended operational tests, Duke pe/ formed liquid penetrant examinations on all of the bosses in all of the 1A engine subcover assemblies. They found two subcovers with cracked bosses. All others were found to be free of defects.
Although none of these failure had caused a loss of operability of the engine, Duke has replaced all of the affected covers.
Duke reported that the fractured boss was apparently due to installation l
with a misaligned dowel pin. A failure analysis of the cracked bosses in the other suocovers is being conducted by FaAA.
Duke has reported that, until the cause of failure and the frequency of cracking are better established, they will periodically inspect the subcover assemblies at Catawoa to verify that additional cracking has not occurred.
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I PNL Conclusions Subcover assemblies and their failures were observed during PNL's Catawba site visits in April and July 1984 PNL concurs with Duke's identification of the problem and'its cause, and concludes that. Duke's actions, namely replacing the subject components containing failures and providing for future inspection, are adequate to address this problem. However, Duke should provide confirmatory information on the scheduling and extent of future inspections.
This should be incorporated into the periodic maintenance, inspections, and surveillance of these items on the Catawba lA and 18 diesel engines.
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Component: Intermedfate Rocker-Arm Sockets Part No.: 02-390A '
Brief History of Component Duke Power Company reported that two of the intermediate rocker arm sockets were found to be chipped and/or to have cracks on their peripheral lips. However, these chips and cracks did not adversely affect functioning of the socket or interfere with engine operation because the push rods normally seat into the socket well inside the area where the chips or cracks were found.
Owners' Group Status The intermediate rocker arm socket is included in the Owners' Group DR/QR Program. The report for Shoreham concluded that similar assemblies were 4 acceptable for their intended design function at Shoreham.
Ouke Power Company Status Duke examined the failed components and reported finding no evidence of the chips 'or cracks propagating into the functioning part of the socket. Duke believes the problem is due to improper installation of the rocker arms prior to valve adjustment such that excessive clearance existed, allowing the push rod to move and contact the lips of the socket.
All other sockets in the 1A diesel engine at Catawba were visually
~
inspected by Duke Power Company. No other problems were found or noted during these inspections.
Duke considers the chipped and cracked sockets to be only a cosmetic problem.
In their opinion, there has been no detrimental effect on diesel engine operability. Duke has instigated procedural changes to assure that excessive clearance does not exist in the rocker arm assembly; this action is '
expected to prevent recurrence of the problem.
PNL Conclusions The intermediate rocker arm sockets were visually examined by PNL personnel and consultants during their visits to Catawba in April and July 4
1984 PNL reviewed the problem with Duke personnel during the July 1984 4 .
39 9
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PNL concurs with Duke's analysis of the cause of the failures
{ experienced to date in the subject components. PNL also concludes that, if t
Duke follows their newly instigated procedures, the intermediate rocker arm sockets can be expected to meet their intended operational requirements, t
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Component: Exhaust Valve Tappet (Rocker Arm Ad' justing Screw Swivel Pad)
Part No.: 02-3908 l
Brief History of Component Duke Power Company has reported that.one of the swivel pads on the 18 diesel at Catawba was found to be cracked.
Owners' Group Status This component is included in the Owners' Group DR/QR progr.am. In the DR/QR report for Shoreham Nuclear Power Station on a similar assembly, it was '
concluded that the entire intake / intermediate and exhaust rocker shaft assemblies are acceptable for their intended design function at Shoreham.
Duke Power Company Status Duke conducted a failure analysis of the one failed swivel pad and reported that it was swaged or rolled more excessively than were the other screw swivel pads. They concluded that this apparent one-time manufacturing defect caused an overload on the pad, resub:ing in its failure.
Using visual and liquid penetrant exan. nation techniques, Duke has inspected all 64 swivel pads on the 1A engine at Catawba. They have reported finding no defects; all of the inspected sockets appear to be consistently and properly swaged.
PNL Conclusions The subject components were examined by PNL personnel and consultants during the Catawba site visits in April and July 1984 PNL concurs that the results of Duke's analysis appear to be logical and supportable. PNL concurs with Duke that the swivel pads now installed in the 1A engine at Catawba are satisfactory and should be capable of meeting their functional requirements for the life of the diesel engine as dependent on the manufacturer's recommended j
maintenance and/or replacement programs. It is also assumed tnat the pads on the 1B engine are also capable of meeting their functional requirements.
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Component: Intake and Exhaust Valves Part No.: 02-3608 Brief History of Component During the disassembly and inspection of the 1A engine at Catawba after the extended operational tests, Duke found nine exhaust valve stems with areas of flaked or peeling chrome plate. The separation of chrome occurred from about 6 to 8 inches above the seat of the valve and at a location corresponding to where the stem enters the valve guide. Duke has reported that separation of the chrome had no effect on the diesel engine operability.and did not cause any o'b servable damage in the valve guides. The valves themselves have undergone over 800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> of engine operation, with at least half of that at engine loads over 185 psig BMEP.
Owners' Group Status Intake and exhaust valves are included in the DR/QR Program. The-Shoreham i
DR/QR report on intake and exhaust valves concluded that flaking and loss of chrome plating from the valve stem is an isolated event that has a minor effect on engine performance. It was reported that fuel used at Shoreham does not contain significant quantities of sulfur, and corrosion of the alloy steel stem will be minor if chrome is lost. There may be some increase in oil leakage past the stem seal, but this will not affect engine' operation. Thus, an iso-lated occurrence of chrome loss will not significantly affect engine reliabil-ity. The report concludes that the valves are acceptable for their intended design function at Shoreham.
Duke Power Company Status Duke Power Company observed no structural damage in the valve stems where i
chrome plate flaking or peeling occurred. During the Catawba site visit in July, Duke reported that the affected valves were replaced during the reassembly of the 1A engine.
PNL Conclusions The chrome peeling on the valve stem was noted during the April and July 1984 visits to the Catawba plant by PNL personnel and consultants. 9NL agrees l
42
with Duke that the chrome peeling found on the valve stems is of only minor importance. However, because this peeling could possibly allow corrosion and an accumulation of corrosion products that could eventually affect the operation of the valve and/or the valve guide, valve replacement is considered necessary. This has been completed on the 1A engine; PNL concludes it should be done also on the IB engine.
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Component: Spring Retaining Nut and Roll Pin on Air Start Valves Part No: 359
. 1 Crief History of Component During the extended operational testing of the 1A diesel engine at Catawba, Duke Power Company found the spring retaining nut on one air start valve was jammed due to galled threads. In addition, a spring retaining nut roll pin was missing from another valve. Duke reported that neither the galled threads nor the missing roll pin had any adverse effects on the diesel's operability.
Owners' Group Status The subject air start valve is an assembly included in the OR/QR program.
The DR/QR report for the Shoreham Nuclear Power Station documents the design and quality revalidation reviews conducted on the assembly and its equivalent components. The final conclusion of this report is that the air start valve, as an assembly including these components, is acceptable for its intended design function.
Duke Power Comoany Status All of the air start valves on the Catawba 1A engine were disassembled and visually inspected by Duke personnel. The one jammed nut and the one missing roll pin were the only deficiencies found on the 16 subject valves of engine 1A. -
Duke has expressed the opinion that the jammed nut and missing roll pin were the result of installation errors. These items have been replaced. Duke has also implemented installation procedures to assure that similar omissions or problems will not recur.
PNL Conclusions The subject deficiencies were reviewed with Duke by PNL personnel and consultants during the Catawba site visit in July 1984 PNL concurs with 44 l
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Duke's assessment of the problem, its cause, and its correction, and concludes that similar errors are not likely to occur in any subsequent engine reassembly, provided that appropriate procedures are followed.
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Component: Crankshaft Part No: 02-310A Owners' Group Report: FaAA-84-4-16 (dated May 22, 1984)
Brief History of Component I- .
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Three V-16 crankshaft failures have been reported, all in the non-nuclear industry. Two failures were attributed to torsional stress due to operation too close to the critical speed.. No cause has been suggested for the third failure. There also have been failures of shafts of other TDI R-4 engine models. However, because of the individual nature of shaft stresses, such are not necessarily germane to V-16 engines in general nor to ,the Catawba engines specifically.
Owners' Group Status Failure Analysis Associates has performed torsional and bending stress analyses of the subject crankshaft and has concluded that the shaft will meet the Diesel Engine Manufacturers Association (DEMA) standards at the engines' nameplate rated load and speed. The radius of the fillets in main journal oil 4 holes was identified as an area of potential stress concentration, and careful inspection of this area was prescribed. PNL's review of the FaAA report on these shafts has not yet been concluded. Various considerations remain pend-ing, in the view of PNL's diesel consultants, and must be adequately addressed and favorably resolved before PNL could be confident that the shafts can be shown analytically to be able to function properly over their expected func-tional life at their design ratings, and also accept such excursions in load, 4
load balance, and speed as sometimes occur with engines.
) Ouke power Company Status Both Catawba engines have undergone extensive operation, with over 750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br /> on each; more than half of the loads were above 185 psig BMEP. These crankshafts in the Catawba diesels have 13-inch diameter crankpins and 13-inch diameter main bearing journals, as opposed to the failed R-48 shafts at
, Shoreham with 13-inch main journals and 11-inch crankpins.
46 1
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The completed in situ inspection of the 1A diesel crankshaft included:
e web deflection measurements g e torsfograph tests (with the AN piston skirts) o visual inspection of all crankpin journals and the fillets at either end e
eddy-current testing of all crankpin-to-web fillets except for those of crankpin #2 e
visual inspection of main bearing journals and journal-to-web fillets for 50% of the main bearings (#4, #5, #6, and #8) e fluorescent dye penetrant testing of the Tube oil holes in main journals #4, #6, and #8.
No visually discernible indications were found on the crankpin fillets.
Minor indications were detected on the crankpin-to-web fillets on crankpin #7 and on the #8 main journal oil hole.
The indications found as a result of the eddy-current testing and the fluorescent dye penetrant test were polished out in less than 0.020 inch.
The 18 diesel crankshaft inspection will include web deflection measurements and visual inspections of the crankpin journals and fillets.
Duke has concluded that the 1A crankshaft evidences no meaningful, deleterious prablems, present or potential, and that it is serviceable for its designed funct.co.
PNL Evaluation and Conclusions PNL consultants have reviewed report FaAA-84-5-23 entitled Torstograch Test of Emergency Diesel Generator 1A at Catawba Nuclear Power Station. They concluded that this test, conducted on the 1A engine while it contained AN piston skirts, is representative of what would be expected of similar tests of the same engine with AE piston skirts installed. Therefore, PNL does not see the need to conduct additional torsiograph tests on the 1A engine at this time. As discussed in this TER, Duke has completed extended operational tests on the 18 diesel engine at Catawba that consisted of 47 i
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4 sufficient operating time to indicate the crankshaft is capable of the intended service. Further, in the July 6,1984, letter to NRC, Duke has identified the tests and inspections they plan to perform on the crankshaft of the IB engine. In PNL's viewpoint, this proposed test and inspection program are {
adequate to verify the physical condition of the IB crankshaft. Assuming that the results of Duke's test and inspection program are satisfactory, then PNL would not have any reservations about the crankshaft of the 18 engine being capable of performing its intended functions, at least until the next reactor refueling outage.
Because the relevant Owners' Group analyses of RV-16 crankshafts are not yet finalized to acceptable conclusions, in PNL's view, PNL cannot conclude in an unqualified manner that the Catawba shafts are unreservedly reliable.
However, PNL does cenclude that sufficient operating time has been accumulated i
on the 1A engine, and that adequate inspection tests have been performed on the crankshaft in the 1A engine, to verify its adequacy to perform its intended functions at least until the next reactor refueling outage, provided the engine operating BMEP is kept below 185 psig. It is PNL's understanding that Duke's
] emergency load profile meets this condition. By the next reactor fueling outage, it should be possible to draw de'finitive conclusions on these shafts.
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Component: Connecting Rod Bearing Shells Part No: 03-340-B1 Owners' Group Report: FaAA-84-31 Brief History of Component No total failures of the TDI DSRV type diesel engine connecting' rod (conrod) bearing shells have been reported in nuclear applications. However, some have been replaced because of deterioration due to inservice conditions or because they were found to be in nonconformance with Owners' Group recommendations regarding voids in the base material.
Owners' Group Status Failure Analysis Associates has conducted both stress and orbital analyses on the conrod bearing shells. They concluded that the bearings are suitable for the intended service, provided 1) they conform to the manufacturer's specification and 2) they meet a criterion for subsurface voids developed by FaAA for the Owners' Group.
Duke Power Company Status '
The engines at Catawba, with original bearing shells in place, have each operated for over 750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br />, more than one-half that time at loads above 185 psig.BMEP. That is approximately the maximum gpergency load (LOOP and LOCA) 'for which these engines were selected.
All (100%) of the conrad bearing shells for the 1A diesel engines at Catawba were examined using the following techniques:
a thickness measurement
- visual inspection of bearing and back surfaces e liquid penetrant examination a radiograph examination.
These inspections are now underway on the IB conrod bearing shells, i i
The thicknesses of the bearing shells from the 1A engine were found to be within specification. Visual and liquid penetrant examinations showed deterioration of the babbit layer in the areas where maximum pressure is 49
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. exerted on the bearing. . Duke has concluded that this deterioration is the result of normal wear; it had not progressed to the point at which engine l
operation would be affected. Therefore, Duke determined that the bearing shells are acceptable for reuse.
Radiography-detected five conrod bearing shell halves that contained voids larger than specified by the Owners' Group' criterion. During the July 1984
[ site visit, Duke personnel indicated that the upper and lower bearing shell halves of no. 5, 6, and 7 conrods were replaced in the 1A engine at Catawba.
PNL Evaluation and Conclusions The subject bearing shells from the 1A engine were not available for pNL inspection during the Catawba visit in April 1984 However, photographs of the bearing surface of each were reviewed. During PNL's visit to Catawba in July 1984, the bearing shells from the IB engine were viewed by PNL staff and consultants. The deterioration noted in both sets of bearing shells has been reviewed and discussed. PNL's consultants conclude that this deterioration could be the result of insufficient oil pressure, and PNL recommends that Duke investigate this possibility. PNL concurs with Duke that the subject components retain sufficient service life for reinstallation and use. However, subsequent inspections should be made on the bearing shells within the next 500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> operation to verify their continued integrity. This is approximately i
the operating time expected over the next 10 years 'and agrees roughly with Duke's inspection plan. Duke's planned regular monitoring of the lube oil for
~
contaminants, such as bearing babbit metal, will help assure reliability of these components.
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! Component: Cylinder Blocks Part No: 02-315A ( ,
Owners' Group Report: FaAA-84-5-4 i
Brief History of Component
~ Numerous incidents of cylinder block cracking have been reported in the non-nuclear field. In the nuclear field, all three engines at Shoreham have cracks in their cylinder blocks. At Comanche p'eak, cracks were observed after 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> of operation. None has resulted in catastrophic engine failure or emergency shutdown.
A number of engines have continued to operate many hours with known cracks.
Affected areas are primarily the cylinder liner landing area, between the .
cylinder opening and adjacent head stud holes, and between adjacent cylinder head stud holes.
.c Owners' Group Status '
Failure Analysis Associates performed strain gauge testing combined with two-dimensional analytical modeling of the block top and liner. In their i
report only recently published, FaAA concluded:
Eventually, depending upon sufficiently high load and operating hours, cracks will initiate between stud hole and liner counter-bore. Cracks are predicted to be benign (e.g., non-propagative) if the block materials are free of deleterious materials and properly cast, and if engine loads remain below 225 psig BMEP. [That some (such as those at Catawba) have operated many hours at loads at and exceeding these levels without even initial crack indications is, in FaAA's opinion, indicative of the conservative nature of their evaluation.]
e Cracks between stud hole and liner counterbore will increase the likelihood of cracks developing between stud holes of adjacent cylinders. The deepest crack measured in this region (5-1/2 inches j
in depth at Shoreham) did not degrade engine operation or loosen .
studs.
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', o Provided there are no cracks between stud holes between adjacent Y' '
cyiinders,theblockispredictedtohavesut.icientmarginto withstand a LOOP /LOCA event.
The FaAA report recommends visual and eddy-current inspections'of cylinder blocks at intervals relate'd to load and operating hours.
Og Power Company Status
~~ Both Catawba engines have operated over 750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br /> each, over half 'of that time =at loads. exceeding 1135 psig BMEP.
The block inspection for the 1A diesel, which revealed no cracks, included:
a liquid penetrant examin'ation of all cylinders around the studs, and between the cylinder st'uds and liner
" o dimensional and liquid jenetrant examination of the cylinder liner landing area of seven cylinders 3
eddy-current testing of stud holes of these seven cylinders.
The proposed inspection p'lan for the IB engine will include only 25% of the block (four cylinder areas), covering only dimensional and liquid penetrant
'xamination.
e -
PNL Evaluation and Conclusions . '
After reviewing the FaAA report and noting that Duke's inspections of the t
lA engine blocks revealed no indication of cracks, PNL concurs that the blocks are acceptable for their intended purpose, at least until the next reactor refueling outage. PNL's conclusions regarding the scope and frequency of inspections are expressed'in Section 7.0.
~
- If the results of Duke's inspections on the cylinder blocks of the IB engine are satisfactory, PNL would have no reservation about the continued use
_of these components and their ability to fulfill their intendeu purpose.
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e, . a, o Component: . Cylinder Liners Part No: 02-315C Owners' Group Report: FaAA 84-5-4 Brief History of Component
.Only one incident of cylinder liner "fr*!ure" in nuclez service is j available. This failure occurred in 1982 at Grand Gulf when a pisto, crown separated from the skirt during testing of the Division II engine and marred the liner.
Owners' Group Status The Owners'-Group analysis has identified some cylinder liner dimensions as not being compatible with those of interfacing components. This incompatibility could be a contributing factor in liner stresses.
Duke Power Company Status The original liners on both the 1A and 1B engines at Catawba have served for over 750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br /> of operation, with over one-half that period at loads exceeding 185 psig BMEP.
Cylinder liner inspection on the 1A diesel included those listed below.
The 18 diesel inspection percentages are shown in parentheses.
- visual inspection of 100% of the cylinder line'rs (100%)
- bore measurements of 100% of the cylinder liners (100%)
1 material comparitor and hardness tests on 20i s' c,e liners (0%)
o dimensional check of cylinder protrusic" t r.P ;he block on 100% of the liners (100%)
- dimensional check of the cylinder liner landing area for 40% of the cylinders (25%).
All cylinders showed minor scuffing. Duke has concluded that the scuffs are a result o .ormal wear and are acceptable. Twenty-three percent sf the l bore measurements and 33% of the cylinder protrusion measurements did not meet
! TDI specifications. Duke has concluded that the out-of-specification 53
w .
s measurements are acceptable for used cylinders. Although the material i
comparitor tests showed ' differences from the Owners' Group standard, Duke considers the liners to'be satisfactory based on their performance record. The hardness. test results were found by Duke to be acceptable.
PNL Observations and Conclusions PNL concurs with Duke that the inspections made and the results are acceptable. The Duke conclusions regarding scuffing, bore measurement, and materials composition are judged to be reasonable and supportable. In view of these considerations, the already acceptable service for over 750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br /> in the 1A engine, and the general history of _ reliability of TDI liners, PNL concludes that the liners in the 1A engine are suitable for their intended purpose. If the results of the inspections on the 18 engine cylinder. liners are acceptable, PNL concludes that these liners also will suit their intended purpose.
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Component: Cylinder Head Studs Part No: 03-315-01-0A (Old Design)
-Owners' Group Report: Stone & Webster. March 1984 Brief History -of Component To date, no failure of cylinder head studs.has been reported in the nuclear industry. However, some isolated failures have been reported in the non-nuclear field. The cause has not been reported.
Owners' Group Status Stone & Webster Engineering Corporation has analyzed both the o'1 design studs and new necked-down studs developed by TDI to minimize potential cylinder block cracking, and has concluded that both stud designs are adequate for the service intended, provided proper stud preload is applied.
Duke Power Company Status The original studs in both Catawba engines have experienced over 750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br /> of operation, over half of which has been at loads exceeding 185 psig BMEp.
Duke has not replaced any of the cylinder head studs with the new necked-down design. In the 1A diesel inspection, head studs of four cylinders were.
measured for as-found torque and then visually inspected. Also, material compari, tor and hardness tests were performed on a single stud from each of four cylinders.
The as-found torque was above 1100 ft-lb (1500 ft-lb specified) for all measured studs. Duke believes this to be acceptable. No significant indica-tions or material problems were detected. The 18 diesel inspection will include a visual inspection of 25% of the cylinder head studs as in the 1A diesel inspection.
PNL Observations and Conclusions t
From the analysis and inspections performed on the subject studs, PNL concludes that the old design as being used at Catawba remains adequate for its intended purpose, assuming all stud preloads are as specified.
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Component: Engine Base and Bearing Caps Part No: 02-305C Owners' Group Report: FaAA-84-6-53 Brief History of Component The only failure reported by the Owners' Group for DSRV-16 engines occurred in a non-nuclear application: a nut pocket failed on a DSRV-16 engine at the ANAMAX mine near Tucson, Arizona. According to FaAA, TDI determined that this failure was due to impurities in the casting material that reduced the engine base strength.
Owners' Group Status Failure Analysis Associates, as discussed in the Owners' Group report, has analyzed the base, bearing saddles, bearing caps, nut pockets, and bolting /
nuts.
FaAA has concluded that the base assembly components have the strength necessary to operate at full rated load for indefinite periods, provided that all components meet manufacturer's specifications, that they have not been damaged, and that proper preloads are maintained.
Duke Power Company Status On engine 1A, 50% of the main bearing saddle area (around four bearings) was checkec by liquid penetrant and visually examined around and between the
, stud holes. In addition, stud tension for removal of the nuts was measured.
No abnormalities were detected. This component will not be inspected as part of the 18 diesel inspection, per Duke's current inspection plans.
PNL Evaluations and Conclusions l
The one reported failure of these components appears to be traceable to a manuf acturing defect in a particular casting. There has been no indication of a similar failure occurring in the 1A engine that has been operated for over 800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br />, with at least one-half of this time at BMEPs of over 185 psig.
PNL concludes that Duke has conducted adequate inspections and, further, that there is no apparent reason why these components cannot continue to perform their intended functions in both of the TDI diesel engines at Catawba.
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l Component: Rocker Arm Capscrew Part Mo: 02-390-01-0G Owners' Group Report: Stone & Webster, March 1984 l
Brief History of Component Rocker arm capscrew failures at Shoreham have been reported. There have been no reports of similar failures elsewhere.
Owners' Group Status Stone & Webster Engineering Corporation, a consultant to the Owners' Group, has performed stress analyses of both the original capscrew design (the type that failed at Shoreham) and a newer design. Stone & Webster has con-cluded that both designs are adequate for the service intended. Stone &
Webster has attributed the failure at Shoreham to undertorquing.
Duke power Comoany Status The rocker arm capscrews at Catawba are of the original design. These capscrews have experienced in excess of 10 million loading cycles in both Catawba diesel engines without reported failures.
Inspections of all rocker arm capscrews on the 1A diesel included:
o measuring breakaway torques o visual examination *
- magnetic particle testing 4 material comparitor and hardness tests.
The range of breakaway torques for the intake / intermediate and exhaust capscrews was 278 to 376 ft-lb and 324 to 498 ft-lb, respectively. Comparing these values to the specified torque of 365 ft-lb, Duke concluded that these ranges were acceptable. Further, no indications or material problems were identified. Due to the satisfactory inspection results on the 1A diesel, Duke proposes to examine the IB diesel rocker arm capscrews visually and by magnetic particle detection only. !
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PNL's Conclusions Based on the satisfactory performance of the subject capscrews at Catawba for over 10 million cycles, PNL concludes that the currently available l components are adequate for the intended service in both the 1A and 18 diesel engines. Also, in view of the satisfactory service performance, PNL concurs with the reduced scope of inspections as Duke has proposed on .the IB engine.
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Component: Connecting Rods Part No: 02-340A Owners' Group Report: FaAA-84-3-14 Brief History of Component Various connecting rod failures have been reported from the non-nuclear field. One failure mode was in the link-rod blade-to-pin bolting, due to loss of bolt preload. Another mode of failure was fatigue cracking of connecting rod bolts and/or the link rod box in the area of the mating threads. No connecting rod failures have occurred in nuclear service.
Owners' Group Status ,
The first failure mechanism cited was fatigue failure of the link rod bolts resulting from loss of bolt preload. The problem and its solution were addressed by TDI in Service Information Memo (SIM) No. 349, dated September 18, 1980. According to this SIM, engines manufactured between 1972 and February 1980 may have been shipped with an insufficient locating-dowel counterbare depth in the link rod or link pin, resulting in unintended clearance between the link rod and link pin as assembled. Under firing load, this locating dowel will yield, allowing the unintended clearance to disappear and resulting in loose link rod bolts. The Owners' Group (through the above-mentioned FaAA report) has determined that there must be zero cletrance under the specified 1
bolt torque of 1050 ft-lb.
The second failure mechanism is fatigue cracking of the connecting rod bolts and/or the link rod box at the mating threads. TDI attributed these rod cracks to " thread fretting." This " thread fretting" was concluded by TDI to
- result frein distortion of the rod bolt under operating loads in the area of the mating threads; the distortion could occur if the bolts had been installed with
, the originally specified bolt preloads. The Owners' Group addressed this concern for the two versions of the connecting rod, namely the original design equipped with 1-7/8-inch bolts and a later design in which the rod boxes are i equipped with a 1-1/2-inch bolts. Stress analysis, including finite element l studies, has been completed by FaAA. Failure Analysis Associates has concluded that both designs are adequate for the service intended, provided conrod bolt i
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preload is checked within time limits specified as related to engine load requirement in terms of percentage of nameplate rating. However, the rod with the 1-1/2-inch bolts has an 8% to 9% higher margin of safety than the rod with 1-7/8-inch bolts because the related rod box structure is more massive with th smaller bolt configuration.
Duke Power Company Status The Catawba engines were furnished with connecting rods employing the 1-7/8-inch bolt. The 1A engine has undergone over 800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> of operation (over 10 million load cycles), with over half of that at engine loads exceeding 185 psig BMEP. The IB engine has been operated for over 750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br />, with over 80% of this time at engine loads exceeding 185 psig BMEP.
The connecting rod bolt inspections on engine 1A were as follows:
visual inspection of 100% of areas subject to wear (rack teeth, washers, seating surfaces) measurement of 100% of link pin and link bushing dimensions (25% for piston pin bushing) material comparitor and hardness tests on 25% (4) connecting rod assemblies (master rod, rod box, and link rod) liquid penetrant test of rod box areas subject to cracking eddy-current inspection of 100% of the rod box threaded holes a
measurement of breakaway torque on 100% of connecting rod assemblies o
inspections of connecting rod oil passages e
magnetic particle testing of 100% of connecting rod bolts 3
visual inspection of the connecting rod contact surfaces e
measurement of the contact of the connecting rod rack-teeth (serratiuns) with the mating part by " bluing", for 100% of the rods 3 o 1 measurement of connecting rod bolt elongation by ultrasonic testing.
Results of the material comparitor and hardness tests, the magnetic particle and eddy-current examinations, and the oil passage inspections showed 1
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o . .-
no abnormalities. Some scratches and pitting'were detected through the visual inspection of possible wear areas, which Duke concluded have no adverse effects. The TDI-allowed clearance tolerance for new piston pin bushings is 10 to 15 mils; for used piston pin bushings, it is 20 mik. The four bushings measured 11 to 13 mils, which is within the specification for new bushings.
The dimensions of the link pin and the link pin bushing were satisfactory in all cases.
l The liquid penetrant test showed a 1-1/2-inch long scratch on link rod bushing IL, which was replaced. Breakaway torque values for the master rods and the link rods ranged from 1260 to 2150 ft-lb (specified torque of 1700 ft-lb) and 880 to 1410 ft-lb (specified torque of 1050 ft-lb),
respectively. Galling under bolt heads was observed in the visual inspection of the contact surfaces. Duke has concluded that the galling was due to bolt torquing and is acceptable. The degree of contact from bluing showed a range of 80 to 100%. The manufacturer requires at least 75% contact. Inspection results are not yet available for the elongation tests.
PNL Evaluations and Conclusions TDI and the Owners' Group have each conducted extensive investigations and analyses of the connecting rod failures. PNL has not been able to reach final closure on the sufficiency of their results, but generally concurs with their conclusions as to the failure mechanisms, subsequent corrective actions, and overall operability and reliability of the components if given sufficient surveillance and maintenance.
Duke has appropriately addressed the generic issue of potential connecting rod problems through extended operations, disassembly. and inspection. PNL concludes from the available evidence that the connection rods on the Catawba 4
engines can be expected to perform their intended function reliably. This is stated, howeser, with the proviso that Duke fully check (and correct as needed) the locating-dowel problem and the rack-teeth contact ratio, and establisn a comprehensiva surveillance and maintenance program (see Section 7.0).
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I Component: Engine Mounted Electrical Cable Part No: 02-6888
! Owners' Group Report: Stone & Webster, June 1984 Brief History of Component No failure of this part has been reported. However, in TDI Service Information Memo (SIM) No. 361, Rev.1, TDI reported that two engine-mounted cables, those ' associated with the Woodward governor / actuator and the Air-Pax magnetic pick-up, represent potential fire hazards.
Owners' Group Status Based on the survey results for Catawba, Stone & Webster has recommended to Duke that they implement TDI SIM 361 and that they replace some of their installed 14 AWG wire with wire that is qualified to the IEEE-383-1974 standard. Stone & Webster has also recommended that Duke verify the time period during which their type N7 sliding link terminal blocks were manufactured.
Duke Power Company Status In their report issued to NRC on June 29, 1984, Duke stated their inten
- tions to replace wiring and implement TDI SIM 361 by September 1984 This report also referenced Duke's program for inspecting sliding link terminal blocks'rather than verifying the manufacturing date of the TDI-provided items.
PNL Evaluation and Conclusions When the electrical cable is replaced with IEEE-38-1974 qualified cable capable of withstanding the ambient temperature that might occur adjacent to the diesel engine proper, PNL concludes that there should be no more concern about the integrity of the cable and its ability to function at the normally expected temperatures.
During the Catawba site visit in July, PNL obtained information from Duke on sliding link terminal blocks. According to these data (Reference 19 to the report issued on June 29, 1984, to NRC), they have found a small percentage of i
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defective links at Catawba. However, Duke reported no incidents of a defective i link causing degradation or failure of an electrical circuit.
)
PNL and its consultants have not completed their review of' either the Stone & Webster reports on the subject components at the TDI Owners' Group plants (including Catawba) or Duke's inspection approach on the sliding link terminal blocks. However, PNL concludes that the terminal blocks as installed at Catawba will be capable of fulfilling their intended functions, at least until the first refueling outage at the reactor.
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Component: High-Pressure Fuel Tubing Part No.: 02-365C Owners' Group Report: Stone & Webster, April 1984 Brief History of Component High-pressure (HP) fuel tubing leaks have developed during preoperational engine testing on Shorehan and Grand Gulf engines. There are no other reported failures in nuclear application.
Owners' Group Status Stone & Webster has analyzed the failed HP fuel tubing and has concluded that the failures originated in inner surface flaws that were initiated during f abri cation. If, through eddy-current inspection, the inner surface condition of new tubing is found to be within manufacturer specification, Stone & Webster t
has concluded the HP tubing is suitable for the service intended, Duke Power Company Status The tubing for both diesels at Catawba has operated satisfactorily for greater than 10 million cycles. Duke proposes to perform eddy-current tests along with visual inspections of the HP tubing of both the 1A and 18 diesel engines. The inspection results have not yet been made available.
PNL's Evaluation -
The isolated failures that have occurred on the high-pressure fuel tubing appear to have been a result of internal flaws. The subject components have neither been a source of problems nor failed on either of tne diesel engines at Catawba during their extended operational tests.
PNL concurs that, if the eddy-current tests show all new or replaced tubing does not contain unacceptable inner surface flaws, then these components should be capable of fulfilling their intended design function.
64 i .
P Component: Jacket Water Pumps Pa rt - No. : 02-425 Owners' Group Report:- Stone & Webster. June 1984 Brief History of Component A TDI engine at Shoreham has experienced a jacket water pump shaf t failure. There is no history of failures on jacket water pumps designed for the V-16 engines.
Owners' Group Status Stone & Webster has investigated the jacket water pumps as installed on the TOI in-line and V engines. They reviewed these jacket water pumps .from the standpoints of mechanical ' design, material suitability, and hydraulic performance. Stone & Webster found the pumps such as those installed on the Catawba 1A and IB engines to be acceptable, with a recommendation that a limiting torque be established for one of the pump shaft nuts.
Duke Power Company Status The 1A diesel jacket water pump inspections included:
visual inspection of the driving gear, coupling, and clearance ring material comparitor and hardness tests of the shaft li' quid penetrant examination of the coupling, shaft, and impeller radiography examination of the impeller.
Porosity was noted in the impeller casting. Based on radiography results, Duke concluded that the porosity was acceptable. The jacket water pump will not be inspected as part of the 18 diesel inspection.
PNL's Evaluation The analysis conducted on the subject pump has been quite extensive. PNL concurs with the investigat.ons' conclusions and concludes that the pumps as installed should be adequate to meet their design purposes. However, Duke must check the subject component on the IB engine to assure that the nut holding the 65
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external spline in the shaft taper is neither under- nor overtorqued. Duke should also confirm that the 1A engine jacket water pumps were reinstalled within the recommended torque ranges.
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Component: Air Start Valve Capscrews Part No.: Go-032-114 .
Owners' Group Report: Stone & Webster. March 1984 Brief History of Component No actual failures of these capscrews have been reported. Mcwever, on May 13, 1984, TDI reported a potential defect due to the possibility of the 3/4-10 x 3-inch capscrews bottoming out in the holes in the cylinder heads, resulting in insufficient clamping of the air start valves.
Owners' Group Status Stone & Webster and TDI both have recommended that the 3-inch capscrews be either shortened by 1/4 inch or replaced with 2-3/4-inch capscrews.
Duke Power Company Status Capscrews on both the 1A and 18 diesels were modified prior to the extended operational tests. All of the 1A air start valve capscrews were measured for torque with values varying from 45 to 134 ft-lb. Duke concluded that this range represents an acceptable variation from the specified torque of 100 ft-lb. Twenty-five percent of the 1A capscrews ware measured for length; all those measured were within tolerance. For the 18 diesel inspection, Duke will measure and retorque 25% of the capscrews, ,
PNL's Evaluation PNL agrees with Duke's assessment of the problems. The actions taken by Duke to eliminate the potential interference would appear to be adequate to prevent any subsequent failures. PNL concludes that, with the continued use of Duke's installation procedures to control torque of bolts, studs, and screws to specified ranges, these components will not present future problems on the Catawba engines.
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r 3.3 RESPONSES TO NRC QUERIES ON COMPONENT PROBLEMS In their August 1, 1984, letter to NRC, Duke Power Company has indicated its reponses to, or the actions to be taken on, specific items or issues raised during the Catawba site visit in July. PNL has reviewed this letter and concludes that the response to each item or issue is acceptable, i
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t 4.0 EVALUATION OF CATAWBA 1A DIE'SEL' ENGINE INSPECTION This section. documents PNL's technical evaluation of the disassembly,
' inspection, and reassembly of the 1A diesel engine at Catawba. These efforts were performed by Duke Power Company following successful completion of the planned extended operational tests.
4.1 STATUS AT CATAWBA I
When the extended operational tests were finished in March 1984, the 1A diesel engine had accumulated more than 800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> total operating time. For 50% of this time, the 1A engine was operated with loads at or greater than 5800 kW (186 psig BMEP). A load of 5714 kW (184 psig BMEP) is the maximum required in any emergency postulated for Catawba. Duke subsequently initiated extensive disassembly and inspection of the engine to confirm the condition of i
various parts and to identify any parts requiring repair, replacement, and/or redesign to ensure highly reliable standby electric generator service. Duke's inspection program involved 100% inspection of parts for. which there was a history of problems or other reasons for special concern. Substantial sampling inspections were performed on other important parts for which there was no history of problems.
The inspections of the 1A diesel engine were performed during April through' June 1984 As reported by Duke, the diesel disassembly, inspections, '
and reassembly were performed in accordance with Duke Power Company's Quality '
Assurance Program. The work was performed primarily by Duke personnel; however, selected inspections were performed by Failure Analysis Associates (FaAA), Stone & Webster Engineering Corporation, and others in conjunction with the TDI Owners' Group Program. Duke has stated that the inspections of the 1A diatLi are now co.rplete, except for a few that must be performed during cr following engine reassembly. "Walkdown" inspections of the various piping, tubing, and electrical condaic runs on the enginc are planned following com-pletion of the 1A engine reassembly. Results of these inspections will be factored into the Owners' Group Phase II DR/QR program for Catawba.
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10 uke Power Company's report, entitled Catawba Nuclear Station Diesel Engine 1A Component Revalidation Inspection, dated June 29, 1984, describes the 3
methodolcgy and results of the inspections and examinations performed. I 4.2 TEST AND INSPECTION RESULTS The post-extended operational test inspections on the 1A' engine are now nearly complete. Engineering and quality assurance evaluations of the inspection results have been performed by Duke. They consider this work to have identified all significant conditions.
As reported by Duke, the most significant results of the Catawba 1A diesel engine post-test inspections are as follows:
a e
Many of the major problems experienced with other TDI dies'el engines did not occur in the Catawba 1A diesel engine.
One major problem was noted on the 1A diesel. Four af the type AN piston skirts used in the 1A diesel were found to have one or more cracks in the region where an internal circumferential reinforcing rib intersects the piston pin boss.
3 The turbocharger thrust bearings were found to be severely worn, although they had continued to function satisfactorily during the test. This condition was anticipated because similar problems have be'en experienced at other stations. As a result of this history, a redesigned lube oil system is being developed to minimize possible recurrence of the problem. It will be installed by September 1, 1984 In the meantime, the bearings have been replaced as necessary to ensure operability.
o Several other problems of potential significance to engine 1A
+
operability were detected and are being investigated further as part of the TDI Owners' Group Program:
- Two subcover castings were found to have cracks in an intake rocker arm pedestal.
70
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- Two Catawba cylinder heads (one on diesel 1A and one on 18) experienced small jacket water leaks into the exterior fuel injector cavity. Metallographic examinations of the head removed from the 1A diesel . indicates that the leak was due to a fatigue crack of the spray nozzle hole repair at a weld performed at the TDI factory.
A small eddy-current test (ECT) indication was detected in crankpin-to-web fillet #7 (generator end) on the crankshaft. Metallurgical examination suggests that the indication was due to 0.027-inch and 0.021-inch long linear defects located about 0.105 inches apart. The 0.021-inch ' defect was polished out at a depth of less than 0.005 inch. The 0.027-inch indication was polished out in about 0.020 inch of depth. Another indication was detected by fluorescent dye pene-trant in the #8 main journal oil hole. This indication was approxi-mately 0.2S-inch long and made up of a series of extremely small pores. This indication was polished out in less than 0.005 inch.
Evaluation of these indications shows that they were due to initial
$ fabrication.
J e
A variety of routine minor conditions was noted; these are discussed in Section 3.0 r,f this TER. None of these conditions impacts the i
operability or structural integrity of the diesel. Typical co'nditions included:
- chipped and cracked edges of rocker arm sockets and cracked tappet
- flaked and peeled valve stem chrome plate
- jammed air start valve adjusting nut
- heads of small bolts broken off, due to under- or overtorquing j
- fuel oil injection pump valve holder cracked at a casting defect
- repeate< cracking of the right-bank turbocharger /intercooler adapter
- turbocharger prelube oil line fractures at connection fittings.
4.3 EVALUATION As stated in pNL-5161, Review and Evaluation of TDI Diesel Generator Owners' Group Program Plan, engine testing and inspections are the key elements 1
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l 1
of the TDI Owners' Group Program for tying corrective actions together and for '
verifying adequate results. -
PNL believes that the extended operational tests conducted by Duke on the 1A engine at Catawba, lasting over 800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> (over half of which were at loads of over 185 psig BMEP), were of sufficient length and magnitude and adequate to verify the operability and reliability of components. Further, in PNL's opinion, the tests were adequate to demonstrate whether or not the components will meet load and service requirements without evidence of distress under conditions that could induce high-cycle fatigue.
4.4 CONCLUSION
S.
Based on its evaluation of the activities associated with or reported on the inspection and reassembly of the 1A diesel engine, PNL concludes that Except for the AN piston skirts, the significant engine components were found to be in operable and reliable condition after the extended operational tests, or were appropriately serviced or replaced.
No rasjor problems were found at the end of the extended operational tests that would have prevented the 1A engine from continuing to operate at that point in time.
The miscellaneous problems found have been addressed, and corrective actions have been taken or proposed that should be adequate to prevent a recurrence.
PNL concludes overall that, upon Duke's satisfactory completion of tne return-to-service testing, the 1A diesel engine at Catawba should be adequately operable and reliable to fulfill its intended purpose, at least until the first reactor refueling outage.(a) 1 (a) The phrase "until the first reactor refueling outage" is defined in Section 1.2 on p. 3 of this report.
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5.0 EVALUATION OF CATAW8A 18 DIESEL ENGINE OPERATION TEST AND INSPECTION The Duke Power Company report, Catawba Nuclear Station Extended Operation Tests and Inspections of Diesel Generator, transmitted to NRC on April 5,1984, outlined the inspections that had been performed on the 18 diesel engine prior to operation tests. The report also expressed Duke's intent to extend the IB engine high load operating time to at least 750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br /> and to perfonn additional inspections on the engine and.its components following the extended operation tests.
Duke noted that the extent of the inspections to be conducted on the 18 engine would be based on the results of the Catawba 1A and other TDI emergency diesel engine inspections.
Duke Power Company has now completed its planned extended operation tests on the IB diesel engine at Catawba. During the NRC-pNL/ Duke Power Company meetings on July 25 and 26, 1984, Duke personnel indicated that the 1B engine had been operated more than 750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br />, and that 80% of those hours were at 1 5800 kW. A July 17, 1984, Duke Power Company letter from G. W. Hallman to C.
L. Ray, Jr., summarized the operating history of Catawba Unit I diesels (IA and IB). In an e'arlier letter, dated July 6,1984, from H. B. Tucker to NRC, Duke presented a proposed inspection plan for the 18 engine at Catawba.
5.1 CATAWBA 18 OIESEL ENGINE OPERATION Ouke established the extended operation tests to demonstrate the fatigue resistance of the diesel engine components and to demonstrate the ability of the Catawba engines to operate in a reliable fashion. Duke has concluded that the 810 hours0.00938 days <br />0.225 hours <br />0.00134 weeks <br />3.08205e-4 months <br /> of operation on the 1A engine (50% at 15800 kW) has served to demonstrate the fatigue life capability of the engine parts; that the 1A engine is capable of sustained operation at high loads; and that the 1A engine has the ability to operate continuously for periods of time that may be required in an emergency situation.
According to Duke power Company personnel, the IB engine at Catawba recently sucessfuly completed its extended operation test, which consisted of 73 l
L.
over 750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br /> of operation. Duke has concluded that the 18 engine has demonstrated its ability to operate in reliable fashion.
5.1.1 PNL Evaluation l
As covered in PNL-5161, Review and Evaluation of TOI Diesel Generator Owners' Group Program Plan, engine testing and inspections are the key elements of the TDI Owners' Group Program for tying corrective actions together and for verifying adequate results. Engine tests are required to demonstrate whether or not a component or unit will meet load and service requirements without evidence of unacceptable stress. This is particularly important in plants seeking licensing prior to the full implementation of the Owners' Group Program Plan.
5.1.2 PNL Conclusions As reported in Section 4.3, PNL believes that the extended operation tests conducted by Duke on the 1A engine at Catawba were of sufficient length and magnitude and adequate to verify the acceptable function of components, as well as to demonstrate the ability of components to meet load and service i
requirments under conditions that could induce high-Cycle fatigue.
Likewise, in PNL's opinion, tests of a sufficient duration and intensity have been performed on the 18 diesel engine at Catawba to demonstrate its state 1
of component adequacy, subject to satisfactory inspection results. Over 750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br /> of operation were involved, with nearly 80% at or over 185 psig BMEP.
5.2 CATAWBA 18 OIESEL ENGINE INSPECTIONS i
Duke Power Company has developed and published in the July 6th letter noted above their proposed inspection plan matrix for the Catawba 18 diesel engine.
The sample size of components they plan to inspect on the IB engine, except for a few components, is the same as that performed on the 1A engine.
5.2.1 PNL Evaluation The plans for the 18 diesel engine inspection were reviewed by NRC/PNL and Duke Power Company personnel at the Catawba meeting on July 25, 1984 PNL 74
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considered Duke's plans in light of published results of inspections on the 1A engine, as well as the results to date of the Owners' Group analyses on known issues and DR/QR.
5.2.2 PNL Conclusions In PNL's opinion, the inspection plan is adequate to determine if the key and critical components of the 18 diesel engine have met load and service conditions without undue evidence of stress.
PNL recommends that Duke Power Company perform the following inspection in addition to those listed in their referenced inspection plan:
100% disassembly of link and master rods and in situ inspection (visual and surface nondestructive evaluation) of the link rod bushings. In their August 1, 1984, letter to NRC, Duke has concurred with this activity.
The inspections of the 18 diesel engine have only recently begun and tne results are, of course, not complete at this time. Hence, the unavailability of the IB engine inspection report precludes PNL from evaluating the inspection findings and dispositions. After Duke Power Company has completed the IB engine inspections, they should document the methodology, the findings, and the actions taken. Pending successful completion of the 18 engine inspection, reassembly, and return-to-service testing, it is assumed that the Catawba 19 diesel' engine will have compiled a record that will demonstrate its operability and reliability.
i 75
6.0 REVIEW OF POST-INSPECTION TEST PLAN This section documents PNL's review of the post-inspect, ion tests to be performed by Duke Power Company on the Catawba diesel engines. Elements of Duke's proposed return-to-service tests are presented first. Next, factors and data considered in PNL's evaluation of Duke's test plan are described. Last, the overall conclusion reached by PNL regarding Duke's post-inspection test plan is presented.
6.1 OUKE POWER COMPANY POST-INSPECTION TEST PLAN Ouke Power Company outlined its plans for the return-to-service testing of the 1A diesel engine in a July 6, 1984, letter to NRC (H. 8. Tucker to H. R. Denton, " Catawba Nuclear Station Docket Nos. 50-413 and 50-414"). The planned tests included:
o run-in operations in accordance with the TOI Instruction Manual e ten modified-start (a) load tests of at least 3500 kW (i.e., 50% of nameplate rating) e a 24-hour run consisting of 22 hours2.546296e-4 days <br />0.00611 hours <br />3.637566e-5 weeks <br />8.371e-6 months <br /> at 7000 kW and 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> at 7700 kW (i.e.,100% and 110% of nameplate rating, respectively) e two fast starts (a) to a peak load of 4100 kW (59% of nameplate rating): one start with manual turbocharger prelube, and one without e trip device verification e load rejection test.
During PNL's visit to the Catawba site on July 25 and 26,1984, Duke personnel indicated that these tests could not be performed on the 1A engine before August 1, 1984 Similar tests cannot be performed on the IB engine until the current inspection program is completed and the engine is reassembled.
(a) A mooified start is a start including turbnchargers prelube; a fast start simulates ESF signal with the engine in ready-standby status.
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6.2 EVALUATION '
PNL evaluated the elements of Duke Power Company's post-inspection test plan within the context of two principal items:
o PNL recommendations made earlier to NRC regarding diesel engine preoperational testing NRC-proposed staff actions to improve and maintain diesel generator reliability.
These items are described in detail in the next two paragraphs.
In June 1984, PNL recommended to NRC that preoperational testing be performed on all diesel engines following their assembly, to confirm that the engine is operable (PNL-5161). For engines such as at the Catawba Nuclear Station Unit 1 (viz, a candidate for an operating license prior to completion of the implementation of -the Owners' Group Program Plan) PNL recommended that this testing include the manufacturer's preoperational test recommendations as well as the following elements, if they are not already contained in the manufacturer's recommendations:
ten modified starts to at least 40% of " qualified" load (as defined in PNL-5161) 3 two fast starts to " qualified" load
$ one 24-hour run at " qualified" load. .
PNL had also recommended to NRC (PNL-5161) that, because of the plant-specific nature of engine installations, the owners should prepare detailed plans for engine tests and inspections.
During the July 1984 Catawba site visit, PNL learned of NRC Generic Letter 84-15 dated July 2,1984, that addressed proposed staff actions to improve and maintain diesel generator reliability. Enclosure 1 of this generic letter states:
It is the staff's technical judgment that an overall improvement in diesel engine reliability and availability can be gained by performing diesel generator starts for surveillance testing using engine prelube and other manu-facturer recommended procedures to reduce engine stress and wear. The staff has also determined that the demonstration 77 O
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of a fast start test capability for emergency diesel genera-tors from ambient conditions cannot be totally eliminated because the design basis for the plant, i.e., large LOCA coincident with loss of offsite power, requires such a capability.-
In view of the above, the staff has concluded that the frequency of fast start tests from ambient conditions of diesel generators should be reduced.
PNL reviewers noted that Duke's return-to-service test plan states that all 10 modified start load tests will be performed with a prelube of the engine and that one of the fast start tests will be conducted under preluoe condi-tions. Tne other of these tests will be performed with the engine in ready-standby status without prelube.
PNL also notes that Duke's post-inspection return-to-service test plan calls for a 24-hour run to nameplate rating (22 hours2.546296e-4 days <br />0.00611 hours <br />3.637566e-5 weeks <br />8.371e-6 months <br />) and overload rating (2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />), as detailed in Section 6.1 above. In light of the need for conservative operation relative to crankshaft and cylinder block conditions (as previously discussed in Section 3 of this TER and in Section 4~ of PNL-5161),
PNL concludes it would be inappropriate for Duke to further operate the Catawba engines above 185 psig BMEP, as long as emergency loads do not necessitate such operation.
(Refer also to Section 1 and 2.1 herein.)
PNL also recommends that, as part of the return-to-service tests, Duke observe, record, and report pre-turbine exhaust gas' inlet temperatures at levels of 25%, 50%, 75%, and 82% of nameplate rating (i.e., at BMEPs of 56, 113, 169, and 185 psig).
6.3 CONCLUSION
S Based on its review, PNL concludes that Duke's post-inspection test plan is compatible with NRC requirements described in Section 6.2. It is the opinion of PNL's consultants that TDI engines such as those at Catawba should not be operated above s BMEP of 185 psig except for brief periods, at least until all concerns pertaining to the current crankshaft are fully resolved.
Therefore, PNL recommends that Duke conduct the post-inspection 24-hour runs on the 1A and IB engines at a qualified maximum load of 5800 kW. Finally, PNL
)
78 1
1
concludes that the successful completion of Duke's return-to-service tests will be adequate to confirm that the 1A engine and its associated systems are operable.
l PNL also concludes that similar return-to-service tests on the IB engine will be adequate in scope and objective. However, any failure to meet the objectives of the tests will require reconsideration of this conclusion.
d E
Y 79
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- ya 7.0 REVIEW 0F THE PROPOSED MAINTENANCE. INSPECTION.
. AND SURVEILLANCE PROGRAM r
While reviewing the Owners' Group Program Plan (0GPP), PNL recognized that a comprehensive maintenance and surveillance (M/S) program would be a key aspect of the overall effort to assure future TDI diesel engine operability and reliability, and so stated eventually in its formal review of the OGPP as published in June 1984 (PNL-5161). Recognizing that the Owners' Group Program Plan had not yet specifically addressed M/S activities, PNL recomended that theOwntes'IroupdevelopadefinitiveM/Sprogram(inconsultationwithTDI),
and that, detailed plans based on those Owners' Group recommendations be developed for each engine installation by the individual owners.
Elements of such a M/S plan were initially identified by PNL in letters of April 16 and 17, 1984, to C. Berlinger at NRC (dealing specifically with Mississippi Power & Light's Grand Gulf Nuclear Station). The features of the enhanced M/S program suggested by PNL were subsequently incorporated by the NRC
} staff in a letter to MP&L dated April 25, 1984 A letter from H. B. Tucker of Duke Pcwer Company to H. R. Denton, Office of Nuclear Reactor Regulation, NRC, dated July 16, 1984, addressed " Periodic Maintenance, Inspection and Surveillance of the Catawba 1A and 18 Diesel Engines (Catawba Nuclear Station, Docket Nos. 50-413 and 50-414)." Therein,
- ' Mr'. Tucker references the NRC staff letter of April 25, cited above, as one i'
basis of the Duke Power Company M/S program plan. (Other bases cited by Tucker i
include an engineering evaluation of tha results of the Catawba 1A diesel engine post-extended operating test inspection and the TDI Owners' Group recommendations.) >
Ouke's July 16th letter discussed NRC's coments, and indicated how Duke I
plans to resolve those comments. Table 1 of the letter provided a schedule for
- periodic inspection, maintenance and surveillance.
This section presents PNL's review of Duke Power Company's planned M/S program. Significant features of the program are discussed, folluwed by summary observations and comments.
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7.1 PNL EVALUATION In Section 4 of PNL-5161, Review and Evaluation of TDI Diesel Generator Owners' Group Program Plan, PNL recommended that utilities seeking licen' sing prior to completion of the Owners' Group Plan for M/S and its full implementa-tion by the individual utilities, should provide for enhanced surveillance and maintenance. In general, Duke's July 16t.1 proposal has provided for this, although their program differs'somewhat from the NRC staff's April 25th recommendations. Table 1 provides a comparison of the two approaches (NRC and Duke), and presents a parallel listing of PNL's recommendations. Comments on '
individual component plans follow.
7.1.1 Cylinder Heads i j Barring the engine over is done to detect water in the cylinder, which would indicate a cracked cylinder head (or liner), with water not drained to crankcase. Any substantial water accumulation in a cylinder could lead to severe damage to head and/or piston on engine startup and could seriously impact engine operability. The Duke proposal is to bar-over weekly, rather than daily, to reduce engine unavailability. PNL does not consider this proposal to be adequate for assuring tinely detection of water in the cylinders.
PNL Recommendation PNL recommends a revised schedule for barring-over, as follows:
an initial barring-over at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> (but not over 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />) after engine shutdown
- a second barring-over approximately 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after shutdown thereafter, bar-over immediately prior to any planned engine operation.
The basis-for the change from the earlier PNL recommendation (which called for barring-over the engine every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) is the recognition that, if a leak of substantial, detectable proportions has n'ot occurred within the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of cooldown, it is unlikely that one will develop before the next engine operation. However, because it is still possible, although not likely, for a 81
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TABLE 1. PNL's Reconnendations Concerning Dake's Proposed Maintenance /Survell-lance Plans for Key Components of the Catawba TDI Engines- <
- Component NHC Guidance (April 25) Duke Proposal (July 16 ) PNL Reca==andation ^
Cyllader Bar-over 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after engine Rar-oww within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> af ter Bar-over 4 to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> af ter Heads runs and each day thereafter, engine runs and weekly there- engine runs, and agale after
~
atter, and prior to routine 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and prior to routine starts. starts. -
Engine Block Visually inspect after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Visually Inspect monthly "or Visually inspect da'ly during and Base operation or monthly more often". operation, with it*gnsely lighted ' '
laspection monthly, while operering.
$ Connecting Visually inspect and retorque Check talt preloads at first Visual surface laspection and bolt Rods after 24 starts, 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> of refueling outage (estimated preload ched at 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> or operallon, or 6 months, which- equivalent to 25 to 50 starts 9 months, whichever is first.
over is first. and 50 to 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> of operation).
Lube oil Check for water f ollowing pre- Ched following preoperational Ched for water following preopera-Chsch' _ operational tests, then weekly tests, then monthly or after flonel tests, then monthly or af ter or after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of operation, 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of operation, whichever 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of operation, whichever is whichaver is first. Check is first. Check monthly for first. Dieck for. chemical and monthly for contaminants and water in sump; samlannually partloulate contamination on same water in sump; check filters. for contaminants, mock filter schedule. m ock fllter pressure pressure drop durIng diesel drop hourly during operation, operation.
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. TABLE 1. (cOntd)
Component imC Guldence (April 25) Duke Proposal H uly 16) PNL Recommendatlon Studs /. Spot-checa 255 monthly for Spot-check 255 at each fixtures torque, Check 1005 of air-start valve refueling outage.
- capscreus and 258 of all other Items at each refueling outage.
Push Rods, Visually check after pre- Visually check at each Cens, Tap- Visually check at each refueling operational testing and af ter refueling outage. outage, pets, Etc. each 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of operation.
Ot'nor M/S Standtv: Standtv CD Standtwa g items tube oil iliter diiierential Weekly ideokly pressure - dally Crankshaft deflections - hot and once each refueling cycle; hot Once each refueling cycle; hot to cold every 6 months; hot within within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of shutdown. start in 15 minutes, complete 15 minutes of shutdoun.
within 30 minutes.
Operations: Operations: Operations:
Exhaust temperature - continuous Continuously monitored and Continuously monitored and Irecord hourly) Including pre- recorded (no comment re pre- recorded, including pre-turbine turbine talet temperature. turbine exhaust inlet) exhaust inlet.
Lube oII, Jacket water, Inter- Generally per pHC guidance As per Duke proposal.
cooler temperatures, air pressure (excepting accelerometers, accelerometers - monitor con- which give no readingst tinuously, record hourly.
small leak to weep and accumuldte (i.e., the water be retained by the piston rings), it remains prudent to check for the presence of water before any planned start.
Duke contends that the absence of a history of cracked heads at Catawba precludes the necessity of such precautions. Nevertheless, Duke has offered to bar-over the engine weekly as a precaution. Because Catawba has neither identified the " group" affiliation of its heads, nor replaced all with heads clearly of Group III (when TDI manufacturing QA/QC reportedly was better), it is important that these reasonable precautions be taken so as to assure eng'ine reliability. The desirability of doing so is further substantiated by the cecent occurrence of just such a leak, detected by barring-over, at Grand Gulf Nuclear Station (see Section 3 re: cylinder heads). '
7.1.2 Engine Block and Base i There are three primary structural components to a Vee engine: the base; the crankcase; and the cylinder block. The history of problems in the popula-tion of TDI engines, and relevant analyses by TDI and the Owners' Group, lead PNL to conclude that there is insignificant likelihood of failures to occur in the base and crankcase in external locations where they are visibly discernible. However, there has been a substantial history of cracks on the top of the cylinder block, some of which are visibly discernible and/or detectable by NOE methods without head removal. The Owners' Group generic issue report,(FaAA-84-15-12) calls for careful surveillance of this surface on certain engines at unspecified intervals. By their criteria, however, this would not be necessary on the Catawba engines on a regular basis (until a substantial number of additional operating hours at hign load levels have accumulated).
Duke's proposal is to conduct " visual inspections of the block and base" (and, presumably, the crankcase) " routinely during engine operation, i.e, every month or more oftar. These inspections will be directed at... verifying that dangerous cracks are not propagating from stud holes in the block... and will be limited to those inspections which can be performed without-disassembly of any parts." (Emphases added).
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In light of the ' history of block cracks and the FaAA analysis, PNL and its diesel consultants remain concerned that even at Catawba there remains legitimate reason to maintain enhanced surveillance of the blocks at least through the first opportunity for heads-off reinspection and until a more definitive resolution of the problem is established by the Owners' Group and Duke. Nevertheless, because of the favorable Catawba history, and in light of FaAA's evaluation thereof, PNL concurs with Duke's plan for regular, thorough visual monitoring, which must be done under ~ conditions of strong lighting.
PNL Recommendation PNL recommends routine daily inspection during operating periods, with a-more thorough inspection under strong lighting at least monthly. These should be conducted while the engine is operating.
7.1.3 Connecting Rods In light of the history in the TDI engine population (however limited) of connecting rod link-rod box cracking, bolting problems (viz, some galling, some preload relaxation, some failures), and fretting along contact areas of the serrated teeth, some regular visual inspection and bolt retorquing (or equivalent checking) is deemed warranted. The relevant Owners' Group known-issue report (FaAA 84-3-14) recommends that the interval on bolt retorquing not exceed 200 nours of operation at full load (i.e., manufacturer's cated load),
248 ho6rs at 85% load, or 286 hours0.00331 days <br />0.0794 hours <br />4.728836e-4 weeks <br />1.08823e-4 months <br /> at 75% load. In making that recommendation there was no. differentiation between connecting rods having 1-1/2-inch bolts and those with 1-7/8-inch bolts. Although the history of 1-1/2-inch bolting is reportedly bettar, it apparently is not totally devoid of problems (either experientially or analytically). Thus, even by the Owners' Group's own analysis, it is deemed prudent to establish an enhanced surveillance plan.
i Duke contends that it has experienced no relevant problems or indications thereof, such as fretting of the connecting rod serration teeth. However, some surface " roughing" has been observed, the interpretation and importance of which is viewed differently by Duke and PNL observers. Furthermore, the l
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l equivalent rods (with 1-1/2-inch bolting) at Comanche Peak evidenced apparent fretting somewha't more pronounced, to PNL's observers, than that observed at Catawba.
There is some uncertainty, also, on the required amount of ' tooth' contact area to be expected in a proper fit, and just how the lapping and ' bluing' is to be properly achieved. (' Bluing' is a process of using a thin surface coating of a chemical which, when pressed or rubbed against a mating surface, will be removed where contact is achieved.)
In light of these points, PNL recommends a degree of surveillance somewhat more conservative than that proposed by Duke (viz, at the first refueling outage, generally expected to be at 18 months of operation and, by Duke's own estimate, involving up to 50 starts and 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> of operation).
PNL Recommendation PNL recommends visual surface inspection and bolt preload check at 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> of operation or 9 months, whichever occurs first.
This should conservatively address the Final Safety Analysis Report load levels (for LOOP or LOCA events) for Catawba's units, as well as all pre-operational testing following engine reassembly, and the possible impacts of low-cycle fatigue associated with a multitude of starts. At the same time, this revised pattern will reduce the cumulative downtime required, thereby enhancing engine availability.
7.1.4 Lube Oil Checks .
These checks serve two main functions:
a They reveal any water in the oil, indicative of cracks in water-bounded components or leakage past lower liner seals. Such water can lead to lubrication failures, with potential major damage.
They reveal abnormal wear of bearings and related engine parts.
It is important to collect and analyze samples with sufficient frequency that adverse conditions are detected early enough to avoid eitner engine damage l or engine outage (and possibly consequential reactor shutdown). Upon further j consideration of likely operating patterns at Catawba, PNL and its consultants 86 I
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4 agree that weekly sampling is not warranted. However, PNL does not believe that Duke's proposed 6-month intervals between contaminant analyses is frequent enough to avoid possible problems.
PNL Recommendation PNL recommends the following pattern: !
o Check for water contamination after preoperational testing and. then monthly, or after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of operation, whichever comes first; collect the sample from the bottom of the sump tank, preferably about 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after engine shutdown, at the time of the engine bar-over.
Check for chemical and particulate contamination and imbalance near the close of preoperational testing and then monthly or after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of operation, whichever comes first; collect the sample while the engine is running, immediately prior to shutdown.
Check differential pressure across all filters and strainers hourly during engine operation. -
7.1.5 Studs and Fixtures Loss of preload on cylinder head studs, rocker arm capscrews, and air-start valve capscrews can adversely affect engine operability if it goes unnoticed. The gene: 111y positive experience at Catawba in this regard warrants a less rigorous schedule of checking, which, as proposed by Duke, will reduce engine downtime while head covers are off.
PNL Recommendation PNL concurs with Duke's proposal for a 25%-sample check of head stud and rocker ann capscrew preload at each reactor refueling outage. However, because the air-start valve capscrews are more susceptible to relaxation (due to the associated soft metal gaskets), PNL recommends these be checked 100% at the same frequency. (One consequence of the loss of capscrew preload may be loss of cylinder compression; another will be " torching" of the passage permitted by 4
a " loose" valve with consequential irreparable damage to the head, and with potential risk to operating personnel from high velocity, unnoticeable hot gases.)
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7.1.6 Push Rods, Cams. Etc. j Engine operabi.lity is affected by defects in push rods, cams, tappets, and L
other similar components and their supporting structures. Some of these components at Catawba have suffered damage. Hence, regular visual inspection is needed, although few operating hours are anticipated. The^ difference between the NRC guidance (after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of ' operation) and the Duke proposal (at the first refueling outage, estimated by Duke to involve 50 to 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> of
~
operation) is not considered significant in light of the low wear rate or limited likelihood of structural failure for these components, because all parts will have been inspected recently, and because, in the opinion of the PNL consultants, very little change in the conditi.on of these parts is expected during the 50- to 200-hour operating time involved in the Duke proposal.
PNL Recommendation PNL considers the Duke proposal acceptable.
7.1.7 Lube Oil Pressure Drop The NRC guidance called for the pressure drop across the filters to be checked daily, during engine standby, and hourly during operation. Duke contends that during standby there is little opportunity for contaminants to i
develop so as to plug the filters, and that only~ low, keep-warm flow is t
involved so that a significant pressure drop is not'likely. Although this view is relatively valid, it does not reflect two factors:
Entrained water will tend to plug some filter media (or weaken others), and so would gradually change pressure drops.
The continuous keep-warm flow through the filters will (purposefully) continually " polish" the oil, with gradual buildup of contaminants in
. the media; the material scavenged out thereby itself helps filter even finer particles as time continues.
' Thus, it remains valid to monitor oil filter pressure drops during standby.
However, the difference between a daily check (per NRC guidance) and a weekly ;
check-(as proposed by Duke) is not deemed significant; the latter is considerec acceptable.
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PNL Recommendation i
j PNL recommends a weekly check of oil filter pressure drop during '
standby. The hourly check during sustained engine operation remains important, i
for comparable reasons.
7.1.8 Crankshaft Deflection Checks Three purposes are accomplished in crankshaft deflection checks:
detection of changes in shaft configuration, such as a developing crack in a web or journal e
detection of gradual shifts in shaft support internal to the engine (most likely being significant bearing deterioration) detection of changes in external engine sbpport, as in the concrete foundation, or a shift of shims between the foundation rails and the engine base plate. (The foundation will indeed change shape with prolonged engine operation, tending to hump toward the middle due to thermal growth, which must be reflected in appropriately shimming the engine. It may also undergo long-term permanent change as chemical processes continue within the concrete.)
The NRC guidance was for checks each 6 months, the hot-deflection check being completed within 15 minutes of engine shutdown. Duke has counterproposed a check at each refueling outage, to be completed Within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of engine shutdown. Such an interval would increase total engine availability, of Course.
pNL Recommendations Reflecting all considerations, PNL recommends the following pattern:
Take hot and cold deflection readings at every refueling outage (as proposed by Duke). PNL's consultants deem it unlikely that the expected hours and character of operation in the longer period will raise the risks significantly.
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.The hot deflection checks should be taken immediately after the 24-hour preoperational testing, so as to reflect representative operational foundation temperatures.
The hot checks should be initiated within 15 to 20 minutes after shutdown, and completed as rapidly as possible, preferably within 1/2 hour, and starting with-the last throw of the engine (generator end). Such a schedule, although strenuous, is deemed achievable.
7.1.9 Monitoring Exhaust Temperatures
- NRC's guidance was for continuous monitoring and hourly recording of engine exhaust temperatures, including pre-turbine temperatures. Duke has proposed continuous recording, but with no mention of pre-turbine (inlet) l temperatures. [However, in an August 1,1984, letter to NRC following onsite discussions on July 26, 1984, Duke has agreed to make provision for pre-turbine temperature checks in addition to cylinder exhaust temperature and turbine outlet (stack) temperature, as is already being done.]
PNL's consultants deem it very desirable to monitor the turbine inlet temperature for these reasons:
Monitoring would avoid the possibility of such temperatures exceeding the limits set by the turbocharger manufacturer.
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It is possible for the " average" temperature thereat to exceed the
" average" temperature measured at the individual cylinder outlet (the latter reflects a time-averaged combination of true exhaust temperature and a much lesser quantity of cooler " scavenging air" that occurs during valve overlap in the exhaust / intake strokes).
l This higher actual turbine inlet temperature results from three
! possible conditions: 1) the pulse of hot exhaust and the subsequent, lesser pulse of cool air may not mix, even though two cylinders are involved with each manifold; 2) exothermic chemical reactions tend to contin"e after the cylinder exhausts, even with proper firing timing; and 3) any inappropriate timing of fuel injection can lead to continuing flame propagation during exhaust.
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i Plots of pre-turbine temperatures for such engines as at Catawba show l
1 that, at full load and overload (i.e., the TDI rating of 7000 and 7700 kW, respectively), the temperatures of even properly-timed engines can approach 1200*F (the reported upper limit allowed by the turbocharger manufacturer).
While vanes have not been found missing on the Catawba turbochargers, they have been noted elsewhere on similar nuclear engines. Because the mechanism of the vanes' disappearances has not been identified with certainty, it is important to avoid influences toward thermally-induced failures.
PNL Recommendation-PNL recommends continuous monitoring and hourly recording of turbine inlet exhaust gas temperatures.
7.1.10 Surveillance of Operating Parameters Surveillance of a number of key engine operating parameters is essential to assuring reliable engine performance. The initial NRC guidance and the Duke proposed surveillance generally are quite similar.
PNL Recommendation The Duke proposals are deemed acceptable, with,the clarification that engine lube oil and jacket water temperatures continuously recorded should be discharge temperatures, and that the inlet temperatures should also be monitored, with hourly recording.
7.1.11 Other Inspection and Surveillance
~
In its letter of July 16, 1984, Duke includes Table 1, which lists its proposed " Periodic Inspection, Maintenance and Surveillance Schedule". In general, it reflects sound and acceptable patterns. However, to incorporate the recommendations herein above, some will need to be modified in the final Duke plan. This includes several components that are categorized as needing surveillance or maintenance only every 10 years. PNL does not deem this to be 91
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an acceptable frequency for these, considering the nature of the component, the ove'rall TDI-owner history of problems and indications, and the analyses (to date) of known issues.
PNL Recommendation '
Until DR/QR resolution is achieved on all these items and/or until further l field experience justifies a longer interval such as Duke proposes, PNL comments and recommends sampling inspections as follows: '
Part No. Part Name Remarks /PNL Recommendations l 02-305D Main bearing caps Disassemble two caps and visually inspect at first refueling 02-310B Crankshaft Visual and RT of two highly loaded bearing sets at first refueling bearing shells 02-3408 Connecting rod Dimensional, visual, and RT of bearing shells bearing shells at first refueling 02-341A Pistons Disassemble four pistons and inspect visually and with magnetic particle detection at first refueling 02-360A Cylinder heads Remove four heads and inspect visually and with liquid penetrant at first refueling -
02-390A,B Rocker arms Visually inspect rockers and supports 02-362A Rocker box monthly and check capscrew preloads on assemblies four heads at first refueling.
02-315A Cylinder block Inspect top surface visually monthly in accessible areas. Remove four heads and inspect areas at liner landings and head studs visually and with liquid penetrant at first refueling.
02-315C Cylinder liner Inspect liner surfaces, four cylinders, for surface scuffing or scratching and other signs of lubrication problems at first refueling.
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Assuming the turbocharger prelube system'as finally developed is deemed ade-quote by NRC, the 5-year inspection plan proposed by Duke is acceptable.
Otherwise, at least one turbocharger per engine should be-inspected at the first refueling outage.
7.2 PNL CONCLUSIONS PNL concludes that the Duke proposed M/S activities need some modification to provide adequate assurance of engine reliability / operability. Those recom-mendations, with supporting rationale, are fully delineated above. With those modifications, the Duke proposed M/S program is considered acceptable through the first refueling cycle. As the OGPP and related M/S activities become fully developed and accepted by NRC, it may be appropriate for Duke to modify their plan still further.
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8.0 OVERALL CONCLUSIONS 8.1 GENERAL CONCLUSION In general, PNL and its consultants conclude that the two TDI DSRV-16-4 diesel engines in Catawba Nuclear Station Unit I will have the needed operability and reliability to fulfill their intended emergency power function, at least to the time of the first reactor refueling outage.
This conclusion is predicated upon the known results of the completed extended operational tests and subsequent inspections on the 1A engine, and upon the premise that test and inspection results on the IB engine will prove that it is comparable to the 1A engine. It also reflects PNL's current knowledge and evaluation of the ongoing Owners' Group investigation on specific, generic component issues. Further, it is necessarily contingent upon satisfactory completion of all actions recommended in this TER and upon final reassembly of both engines with satisfactory return-to-service test results, as well as on the assumption that the Catawba-specific OR/QR investigations will further confirm operability and reliability of key components.
8.2 LONG-TERM APPLICABILITY In Section 1.2 of this TER, PNL expressed its opinion and rationale that it cannot responsibly reach unconstrained conclusions on the operability and reliability of the Catawba lA and 18 standby engines. Hence, throughout this report, PNL has expressed its conclusions in such terms as "until the first reactor refueling outage". These conclusions have been predicated upon all evidence available to PNL, including preliminary elements of the OGPP and the Duke OR/QR analyses as applicable to these specific engines. As these analyses are completed and appropriately implemented, and as operational results on these engines (under enhanced surveillance and maintenance) and on others in the general population of equivalent TDI engines are accumulated, it may then be possible to draw unconstrained, long-term conclusions. Until that time, however, the suggested time constraint is deemed essential.
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It is not PNL's intent, however, in expressing this constraint to infer any inherent unreliability or inoperability of these engines, either i specifically at Catawba or in general nuclear standby service.
8.3 KEY CONSIDERATIONS The conclusion stated in Section 8.1 reflects PNL's careful evaluation of all known considerations. Specific considerations have been addressed in Sections 3 through 7 cf this TER and reference should be made thereto for PNL's component-specific conclusions and recommendations.
Certain key considerations warrant emphasise however.
Should remaining inspections, return-to-service testing, or DR/QR analyses at Catawba or functional occurrences in other plants, reveal adverse conditions or results not currently expected, modification of 4
this general conclusion may be warranted.
- The conclusion presumes that relevant emergency loads will not require the Catawba engines to operate under other than momentary loads exceeding 185 psig BMEP.
1 Ouke must implement and rigorously control a plan of regularly barring-over the engines to check for cylinder head water leaks.
An improved, successful turbocharger prelubrication system must be devised and installed.
An improved right-bank turbocharger-to-intercooler connection must be devised and installed.
Dukt. must appropriately revise its surveillance and maintenance i
program to achieve the objectives set out in Section 7 of this TER.
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j PNL-5211 .
DISTRIBUTION No. of No. of Copies Copies ,,
OFFSITE 2 DOE Technical Information Center 17 Division of Licensing Office of Nuclear Reactor K. Trickett, NE-14 Regulation U.S. Nuclear Regulatory U.S. Department of Energy Commission Office of Nuclear Energy
. Washington, DC 20555 Washington, DC 20555 ATTN: C. Berlinger (10) ONSITE M. Carrington (2) i R. Caruso D. Corley DOE Richland Operations Office D. Eisenhut M. Plahuta F. Miraglia .
M. Williams Pacific Northwest Laboratory 12 NRC Plant Project Managers 6 Consultants Division of Licensing
., U.S. Nuclear Regulatory i Commission A. Henriksen
+ Washington, DC 20555 J. Horner ATTN: B. Buckley B. Kirkwood 7 P. Louzecky c' ;' S. Burwell A. Sarsten -
O. Hood J. Webber
$ 0. Houston i K. Jabbour
- T. Kenyon 5 Senior Review Panel
! E. McKenna R. Albaugh 4 M. Miller S. Bu'sh
}
S. Miner C. Hill C. Stable W. Richmond J. Stefano L. Williams E. Weinkam 30 Project Team 2 NRC Division of Technical Information and Document J. Alzheimer Control Washington, DC 20555 M. Clement S. Dahlgren
- 0. Dingee NRC Public Document Room R. Dodge W. Gintner W. Laity (15)
J. Nesbitt F. Zaloudek Technical Information (5)
Publishing Coordination (2)
Distr-1 L -
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- UlC2o5u<e, L-t OBattelle Pacific Northwet Licor.norn.s August 10,.1984 P 0. lfo 999 AFland. Washington U $ \. 99332 Mr. C4-1 Berlinger Teleohone 1309) l 1
Division of Licensing "" u 2sn Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555 i
Dear Mr. Berlinger:
SUBJECT:
" REVIEW AND EVALUATION OF TRANSAMERICA DELAVAL. INC..
RELIABILITY AND OPERA 8ILITY - CATAWBA NUCLEAR STATION UNIT 1", PNL Report No. 5211, prepared for U.S. Nuclear Regulatory Commission by Pacific Northwest Laboratory, August 1984 In Section 7.1.3 of the subject document PNL recommended a' visual surface inspection and bolt preload check of the connecting rods at 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> of operation or 9 months, whichever occurs first. This is consistent with an earlier recommendation made by PNL for the diesel engines at Grand Gulf.
However, the engines at Catawba are equipped with connecting rods of a later design than those at Grand Gulf. In a report on connecting rods prepared for the TOI Diesel Generator Owners' Group. Failure Analysis Associates concluded that the later design has an 8% to 9% higher margin of safety than the earlier design, because the rod box structure is more massive.
Accordingly, PNL has reconsidered its recommendation for surveillance of con- .a necting rods in the engines at Catawba.
PNL now recommends a visual surface inspection and bolt preload check of these connecting rods at 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> of operation or 18 months, whichever comes first. Per discussions with M. Miller of the NRC staff, we understand that this new recommendation has been incor-porated into the Catawba SER.
PNL consultants B. J. Kirkwood, P. J. Louzecky, J. E. Horner, and A. J.
Henriksen, who participated in the preparation of the subject report, con-cur with this new recommendation. If further clarification is needed, please give me a call at (509) 3)5-2332.
Sincerely.
J. F. Nesbitt PNL Otesel Engine 0/R Project
/ M Concurrence: ,
W. W. Laity " ^
f PNL Project Manager y JFNiri ec: M. Miller, NRC A. J. Henriksen i J. E. Horner
- 8. J. Kirkwood i P. J. Louzecky .
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.R mmmM Attachnent 4 ~
, SAFETY EVALUATION REPORT RELIABILITY OF DIESEL GENERATORS MANUFACTURED BY TRANSAMERICA DELAVAL, INC.
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TABLE OF CONTENTS
1.0 INTRODUCTION
2.0 BACXGROUND 3.0 EVALUATION 3.1 INSPECTION RESULTS 3.1.1 Phase 1 Components
. 3.1.2 Phase 2 Components 3.2 PREOPERATIONAL TESTING 3.3 AUGMENTED MAINTENANCE AND SURVEILLANCE PROGRAM 3.4 OPERATING RESTRICTIONS
4.0 CONCLUSION
S ENCLOSURE 1 - TECHNICAL EVALUATION REPORT (TER) BY PACIFIC NORTHWEST LABORATORY, " REVIEW AND EVALUATION OF TRANSAMERICA DELAVAL, INC. DIESEL ENGINE RELIABILITY AND OPERABILITY, COMANCHE PEAK STEAM ELECTRIC STATION, UNIT 1" l
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SAFETY EVALUATION REPORT RELIABILITY OF DIE 5EL GENERATORS MANUFACTURED BY TRANSAMERICA DELAVAL, INC.
TDI PROJECT GROUP DIVISION OF LICENSING COMANCHE PEAK UNIT 1
1.0 INTRODUCTION
In support of its request for an operating license for Comanche Peak Steam Electric Station (CPSES) Unit 1 Texas Utilities Generating Company (TUGCo; i
the applicant) has provided submittals Ifsted below which describe actions taken by TUGCo and proposed future actions to ensure the reliability of the diesel generators at CPSES Unit 1.
- 1) Letter dated April 30, 1984, from George to Denton,
SUBJECT:
Comanche Peak Steam Electric Station Diesel Generator Requalification Program Plan.
- 2) letter dated June 7,1984, from George to Ippolito,
SUBJECT:
Inspection l Results of the CPSES Unit 1 Train A Diesel Generator (1A).
- 3) Letter dated June 29, 1984, from George to Ippolito,
SUBJECT:
Inspection Results of the CPSES Unit 1 Train B Diesel Generator (18).
- 4) 1.etter dated August 1,1984, from George to Youngblooi,
SUBJECT:
CPSES Diesel Generator Preventive Maintenance / Surveillance Schedules and Texas Utilities Responses to the Phase I Recommendations of the TDI Diesel Generator Owners Group. '
- 5) Letter dated August 15, 1984, from George to Youngblood,
SUBJECT:
CPSES Unit 1, Comprehensive Report on the CPSES Diesel Generator Recualifica-l tion Program.
- 6) Letter dated August 17, 1984, from George to Youngblood,
SUBJECT:
Errata Sheet for Comprehensive Report on the CPSES Diesel Generator Requalification Program for Unit 1.
The staff has issued a generic Safety Evaluation Report (SER), dated August 13, 1984, on the Owners Group Program Plan. The generic SER addresses the resolution of known problems, the design review / quality revalidation program, engine testing and inspections, maintenance and surveillance and administrative controls that are necessary to assure diesel engine reliability. The generic SER also sets forth diesel engine requirements for cwners seeking to operate their plants prior to completion of the Owners Group Program Plan.
2.0 BACKGROUND
Concerns regarding the reliability of large bore, medium speed diesel generators <
of the type supplied by TDI at CPSES Unit 1 and at fifteen (15) other domestic '
nuclear plants were first prompted by a crankshaft failure at Shoreham in August 1983. However -a broad pattern of deficiencies in critical engine
I components have since become evident at Shoreham, Grand Gulf Unit 1 and at other nuclear and non-nuclear facilities employing TDI diesel generators.
These deficiencies stem from inadequancies in design, manufacture and QA/QC by TDI.
In response to these problems, thirteen U.S. nuclear utility owners, including the applicant, formed a TDI Diesel Generator Owners Group to address operational :
and regulatory issues relative to diesel generator sets used for standby !
emergency power. The Owners Group program, which was initiated in October 1983, embodies three major efforts.
- 1. Resolution of 16 known generic problem areas (Phase I program) intended by the Owners Group to serve as an interim basis for the licensing of plants.
- 2. Design -eview of important engine components and_ quality revalidation of important attributes for selected engine components (Phase II program).
- 3. Identification of any needed additional engine testing or inspections, based on findings stensning from the Phase I and II programs.
Although the total program has not yet been completed, most of the wor,k leading to completion of Phase I has been performed.
This SER and PNL's TER precede completion of the Owners Group Program (OGP) and staff review of the Owners Group findings. The staff intends to issue an SER on each of the 16 generic components that have been reviewed in Phase 1 of the OGP. Phase 2 of the OGP, a plant-specific design review / quality revalidation of all engine components recessary for engine operability, has not been submitted for Comanche Peak, Unit 1. The staff, with PNL assistance, will evaluate the Phase 2 reports and issue a plant-specific SER documenting its findings. The staff's conclusions regarding interim licensing of CPSES, Unit 1 pending ecmpletion of the items just described are given in this SER.
The staff's position relating to interim licensing has been previously delineated in the staff's generic SER, dated August 13, 1984, on the CGP.
Conclusions reached in this report are based on actions taken thus far by Texas Utilities Generating Company (TUGCo) to enhance the reliability of the diesels, the results of recent diesel inspections, an enhanced maintenance and surveillance program, operating restrictions and staff /PNL review of the l
' ' current status of the TDI Owners Group Program in resolving the TDI engine issue.
The 1A and 1B engines at CPSES Unit I were disassembled during February and March of 1984 for the purpose of replacing type AH pistons with new typt xE pistons. In anticipation of the Owners Group reconsnendations regarding engine inspections, the applicant decided to fully disassemble both engines and perform detailed examinations. During the course of the inspection, many components were replaced either because unacceptable flaws were found, newer component designs existed, or because minor, non-critical flaws were noted. -
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- 3-The diesel generators at CPSES Unit 1 have a continuous rating of 7000 kw and a two hour overload rating of 7700 kw. The engines are DSRV-16-4 models with 16 cylinders arranged in a " vee" along the crankshaft.
3.0 EVALUATION Enclosure 1 to this SER is a Technical Evaluation Report (TER) entitled
" Review and Evaluation of Transamerica Delaval, Inc. Diesel Engine Reliability and Operability - Comanche Peak Steam Electric Station, Unit 1." This TER was prepared by Pacific Northwect Laboratory (PNL) which is under contract to the NRC to perform technical evaluations oof the TDI Owners Group's generic program, in addition to plant-specific evaluations relating to the reliability of TOI diesels. PNL has retained the services of several expert diesel consultants as part of its review-staff. .
The staff, PNL, and its consultants reviewed the applicant's submittals listed in Section 1.0 and have performed an onsite inspection of key engine components in May 1984, while the Train B engine was disassembled.
The staff has reviewed the enclosed TER, and adopts the TER as part of this Safety Evaluation by reference.
The February and March 1984 inspection.results of engine components and resultant actions taken by TUGCo, indicates that the components in the reassembled engines are acceptable for nuclear service for the interim
. period to the first refueling of CPSES Unit 1. This finding is subject to
! a) operating restrictions as identified in Sect. ion 3.4 of this SER, b) success-i ful completion of commitments made by the applicant described in Section 4.0, and c) successful completion of additional actions required by the staff, also described in Section 4.0.
3.1 Inspections and Results Detailed inspections were performed on all Phase 1 components except for the high pressure fuel oil tubing, which will be replaced with shrouded tubing and i
inspected per Owners Group Criteria prior to installation before fuel load, and
, the engine mounted electrical cable which has been previously replaced with qualified cable. The inspections varied depending on the ccmponent but included visual, dimensional verification, material comparator testing, liquid penetrant, magnetic particle, ultrasonic, radiography and eddy-current.
The inspections utilized acceptance criteria established by the Owners Group where available or criteria thought to be conservative by TUGCo where Owners Group criteria did not exist or was not fully detailed. Inspections performed on Phase ' components of the Train A engine were duplicated on the Train B :
engine whereas the Phase 2 components inspected varied between engines. In general, inspections performed on disassembled components were also performed on any replacement parts.
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3.1.1 Phase 1 Components The most significant results of these inspections are an indication on the Train A main bearing saddle, block cracking in the liner landing area of both Trains A and B, and excessively worn turbochargers, most notably the thrust bearings in both Trains A and B. All cylinder heads, push rods and piston skirts were replaced with improved versions of the same component.
Linear indications were found on the Train A main bearing saddles of journals 1, 3 and 9 during visual and liquid penetrant inspection. The Owners Group has concluded that the indications on journals 1 and 9'are acceptable, minor casting flaws. Final disposition of the indication found on journal number 3 has not yet been completed by the Owners Group; however, preliminary results are that the indication is acceptable since a large factor of safety exists against crack propagation. The indication is approximately 1/8" long by 1/32" wide and is located in a corner away from the crankshaft on the horizontal surface of the main bearing saddle. The staff will require that the final evaluation of the number 3 saddle indication and the bases for the conclusions reached on saddles 1 and 9 be submitted prior to exceeding 5% power.
Linear indications were found on the liner landing areas of cylinders 4R, SR.
and 6L on Train A and on the liner landing areas of cylinders 1R, 4R and SR of Train B. The Train A indication on 6L is located on the vertical face of the liner landing " lip." It was examined using eddy-current techniques and found to be non-relevant since no depth could be detemined. The Train A indications on 4R and SR extended along the vertical and top horizontal surfaces of the liner landing " lip" and the vertical surface of the block above the " lip."
These indications did not, however, extend to the block top nor did they extend between the cylinder stud hole and the cylinder counterbore. Since they did not extend between the cylinder stud hole and cylinder counterbore, they are not ligament cracks as defined by the Owners Group; however, in order to define future block inspections, they are considered by TUGCo as thougn they are ligament cracks. Indications on Train 8 cylinders 1R, 4R and SR were evaluated by eddy-current techniques. All were located on the vertical face of the liner landing " lip" and concluded to be rounded and non-propagating with the exception of two indications on cylinders 1R and 4R. Both indications were
. examined with 10x magnification and it was concluded that they are a result of the casting process. The above indications (i.e., IR, 4R on Train B and 4R, 3R on Train A) are fomally under evaluation by the Owners Group pending release of the Phase 2 report; however, block cracking has been analyzed by the Owners Group generically a part of Phase 1. Conclusions reached in that generic evaluation are that the block is satisfactory provided no cracks exist between stud holes of adjacent cylinders and that periodic examinations of the block be perfomed. No cracks between studs of adjacent ./ inders l have been found at CPSES Unit 1. Based on its review and the enclosed TER, the staff concludes that the blocks at CPSES Unit I will perfom satisfactorily
- through the first refueling cycle. This finding is subject to (1) an engine load limit of 185 BMEP as discussed in Section 3.4 below, (2) TUGCo submittal
of an acceptable maintenance and surveillance program as identiffed in Section 3.3 below and (3) final disposition of indications that are under review by the Owners Group. The staff also understands that TUGCo will submit supplemental report (s) by the Owners Group concerning cylinder block strain gage and metallurgical tests as discussed in Section 10.0 of TUGCo's August 15, 1984 submittal.
' All four turbochargers (2 per engine) were inspected and found to have numerous nicks and gouges on turbine and fan blades. Most notably, all four thrust bearings were found to be scratched, scored and excessively worn. On Train A, the rotor assemblies, including thrust collars and bearings were replaced on both turbochargers. On Train B, the entire right bank turbocharger was replaced with a spare and appropriate repairs and replacements were made to the left bank turbocharger. Preliminary conclusions reached by the Owners Group are that worn thrust bearings are a result of quick starts without adequate 'prelubrication and recommends that auxiliary full-flow lube pumps be installed and operated prior to planned starts and that a drip lube system be installed to minimize wear on unplanned starts. CPSES Unit I has had the auxiliary full-flow pump installed prior to performance of any preoperational testing, however, the pump
( was not used prior to planned starts. Sites that have used the auxiltary full-i flow pump prior to planned starts (i.e., Grand Gulf, San Onofre) have not experienced any unusual wear. The starts that have occurred at CPSES Unit 1 i after the' recent engine inspection and reassembly have included thrust bearing pre-lube via the auxiliary full-flow pump prior to the start. TUGCo has committed to follow the Owners Group recommendations to provide adequate lubrication via the auxiliary pump prior to planned starts and to modify their i
arip lube system prior to fuel load to minimize wear during unplanned starts.
Additionally, TUGCo has committed to follow Owners Group recorrendations regarding turbocharger inspection intervals based on number of engine starts and will inspect the thrust bearing of one turbocharger at the first refueling shutdown even if the number of starts accumulated on a diesel is less than that reccmmended by the Owners Group. Based on these commitments and ccmmitments to other Owners Group recommendations regarding the turbocharger, the staff concludes that the turbochargers will perform adequately through the first
- cycle of operation.
j During the recent disassembly, TUGCo replaced Type AH piston skirts which were originally installed in the engine with Type AE skirts. Although none of the type AH skirts had failed at CPSES, TUGCo felt that the AH skirts were similar
' to Type AF skirts which have developed cracks at other installations. By analysis, the AE skirts are superior to the AF skirts. Additionally, no reported failures have occurred on similar type' AE skirts in the R-5 engine test which included approximately 600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br /> of operation at higher loads than
, tr le postulated to occur at CPSES Unit 1.
4 During the inspection, three rejectable indications were found on " ball-end" pushrods, and as a result, TUGCo replaced all pushrods with " friction-welded" i rods. The " friction-welded" rods have been analyzed and tested by the Owners Group with acceptable results.
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TUGCo also elected to replace all 32 originally installed cylinder heads (non-Group III) with heads designated as Group III. Group III heads incorporate design changes to improve casting control and other quality control improvements. Most instances of. cracked heads in TDI engines have involved Group I. Inspections performed on heads removed from Train A resulted in three heads having firedeck thicknesses below the minimum specified by the Owners Group.
3.1.2 Phase 2 Components Of the Phase 2 components inspected that were found to be unsatisfactory on at least one engine, the staff judged camshaft bolting, turbocharger support bolting, main bearing shells, rocker arms and subcovers, intake and exhaust valves, intake manifold flanges and starting air distributors to be components l whose failure could significantly affect engine operability / reliability.
Through a combination of infonnation provided in the licensee's August 15, 1984 submittal, discussions with the ifcensee, and the judgment of PNL diesel consultants, the staff concludes that appropriate actions have been taken, where necessary, to insure the reliability of the above ccmponents. However, the staff will require that the starting air distributor on the Train 8 engine be inspected in light of the wear found on the Train A starting air distributor coupled with the relatively short service life experienced. The action must be performed and the results reported to the staff before exceeding 5% power.
3.2 Precoerational Testing Prior to disassembly and inspection, each diesel had been run for approximatel'y 92 hours0.00106 days <br />0.0256 hours <br />1.521164e-4 weeks <br />3.5006e-5 months <br /> (including factory run times of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and 50 minutes for Train A and 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and 35 minutes for Train B) at varying loads' that averaged between 62 and 63 percent of continuous rated output. During this preoperational testing, the Train A and B engines had been started 67 and 83 times onsite, respectively.
! Included in the starting and run times was the successful completion of testing required by Regulatory Guide 1.108, Revision 1. The only instances of unsatisfactory engine response during these preoperational tests occurred during the first and third test of the Train A engine. These instances involved (1) blown fuses from a defective light bulb in the standby voltage regulator and (2) a foot valve installed incorrectly by the manufacturer which resulted in icw oil pressure.
Following engine disassembly, inspection, and subsequent reassembly, preoperational tests specified in NRC Regulatory Guide 1.108, Revision 1, as modified in the staff's letter of August 2,1984, were again perfanned. These tests included additional tests specified by the staff in that same letter, namely: '
- 1) Ten modified starts to 40% load.
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- 2) Two fast starts to a lead greater than or equal 'to the maximum emergency loads the engines are predicted to experience but not greater than a load corresponding to 185 psig brake mean effective pressure (BMEP).
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- 3) One 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> run at a load greater than or equal to the maximum emergency loads the engines are predicted to experience but not greater than a load corresponding to 185 psig BMEP.
The licensee reports that 45 starts were performed on Train A and 54 on Train 8 during the post inspection testing. During these tests, one of the fuel injection pumps on the Train A engine failed and was replaced. The cause of failure is under investigation by TUGCo, however, preliminary indications are that the bolts on the top of the pump were improperly torqued by the vendor after refurbishment. Also, the phase metering potential for the Train A engine was lost due to failed solder joints on screw-in type fuse holders. All screw-in fuse holders were subsequently replaced by cartridge-type fuse holders. The staff found no unusual failures in the post inspection testing and believes that the failures reported are routine and that the actions taken by TUGCo are appropriate. The staff will require that final evaluation of the failed fuel injection punp as well as the supplemental report describing preoperational test results be submitted to the staff prior to exceeding 5% power. The supplemental report should verify that the
, fuel injection pumps on both engines were checked for proper torque and j document any failures to start along with the diagnosed cause, and the i corrective action taken, i
3.3 Augmented Maintenance and Surveillance Program PNL concluded in the enclosed TER that modifications to the Augmented Maintenance / Surveillance Program proposed by the applicant in their August 15, 1984 submittal are needed to provice adequate assurance of continued engine t
reliability / operability. In the applicant's submittal, maintenance and inspections of certain components that the staff believes should be inspected l periodically was not addressed. Additionally, the proposed maintenance or maintenance intervals of certain components was not acceptable to the staff and should be revised by TUGCo. These modifications are discussed in detail i
I in Section 5 of the enclosed TER.
Accordingly, the staff is requiring that TUGCo submit a revised Augmented Maintenance / Surveillance Program incorporating the modifications identified in Section 5 of the enclosed TER. (PNL reconnended modifications in Table 5.2 of the enclosed TER are excepted from this recuirement; however, the staff suggests that the reconnendations in that Table should be carefully considered by TUGCo, consistent with good engineering judgment, in establishing their program.) The revised program must be submitted for NRC review prior to plant operation in excess of 5% power.
Items requiring maintenance and inspection that were not included in the licensee's August 15, 1984 submittal or require revision are:
- 1. Engine base / engine block
- 2. Connecting rods
- 3. Pistons i_ 4 Cylinder heads
- 5. Studs and fixtures
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- 6. Crankshaft deflection checks
- 7. Main bearing shells 8.' Connecting rod bearing shells
- 9. Cylinder liners
- 10. Jacket water pumps
- 11. Lube oil check Engine surveillance data to be monitored during operation that was not included in the applicant's proposal and deemed necessary by the staff are:
Item . Staff Guidance
- 2. Intake manifold Air Pressure
l 4 Visual Inspection for leaks Check hourly Revisions to the standby surveillance data proposed by the licensee that are required by the staff are: 1) the differential pressure of the keepwarm oil 4
filter be monitored weekly and 2) testing of the jacket water for pH, conductivity and corrosion inhibitor be performed after adding make-up water or monthly The applicant has informed the staff that the Owners Group will soon issue a comorehensive maintenance / surveillance plan and that TUGCo plans to adoot it, as appropriate, to supersede their current proposal. In light.of this,'the above staff requirements regarding maintenance / surveillance may be revised s after staff review of the Owners Group maintenance / surveillance plan.
l 3.4 Operating Restrictions 1
PNL recommendations and conclusions regarding TDI diesel engine reliability at CPSES Unit I are predicated on the following assumptions:
- 1. The emergency service requirements the applicant currently forsees for CPSES Unit I will not exceed engine load corresponding to a brake mean effective pressure (BMEP) of 185 psig. Thc need for this assumption is based on PNL concerns regarding the acceptability of crankshaft stresses and AE piston skirt stresses at higher BMEP loadings, and because of open items in the implementation of the Owners Group Program Plan.
l 2. All future engine testing, including surveillance testing required by the
! \. plant Technical Specifications, will be limited to within :5% of the nominal engine load where the upper limit of this load range corresponds to a BMEP of 185 psig.
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I 3. In the absence of the Owners Group completing all elements of their
- program plan, PNL's conclusions are plant-specific, applying only to CPSES Unit 1 and are applicable only during its, first reactor refueling l . cycle. It is understood by PNL that at the first refueling, the applicant
- will implement all apclicable recommendations of the Owners Group and staff.
Regarding item (1), the applicant has calculated that 185 psig BMEP corresponds to a generator load of 5980kw at CPSES Unit 1. As noted in Section 6.1.1 of the enclosed TER, PNL finds that this' evaluation did not consider the generator efficiency. Using an estimated efficiency of 0.96, PNL calculated that the 185 psig BMEP limit corresponds to 5740 kw. The staff, therefore, concludes
'that the appropriate load limitation is 5740 kw. The applicant has reported that the maximum emergency service load requirements are 4200kw Yar the Train A diesel and 4350kw for the Train B diesel, both of which occui for the design basis accident conditions (LOCA) coincident with loss of offsite power (LOOP).
The loads were obtained from actual readings taken in the control room as sequencing-of actual emergency service loads onto the diesels was performed for LOOP and LOOP /LOCA conditions during the recently completed post inspection testing. Thus, there exists sufficient engine capacity at 185 psig 8MEP'to assure that the fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded and that the core is cooled and containment integrity and other vital functions are maintained in the event of postulated l
accidents as required by GDC-17. However, the applicant should submit a revision to the CPSES FSAR, as a;;propriate, to demonstrate that the maximum emergency load requirements are within the 5740 kw load limitations being placed on the engines.
l With regard to item (2), the applicant has comitted to change the Technical Specifications to limit monthly and 18 month diesel generator surveillance testing to a load corresponding to'185 psig BMEP, which the staff concludes is 5740Kw. The testing shall also be perfonned at a load which envelopes
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the maximum emergency service load requirements of 4200kw and 4350kw. The staff will require that the applicant modify the loss of offsite power procedures to assure that the enginas are not unnecessarily loaded above a load corresponding to 185 psig BMEP. Future operator training with respect to this procedure should explajn the basis for the restriction and aspects
"=y to be taken into consideration in its application.
With regard to item (3) above, the staff will include the following license
- endition in the operating licensee:
Final evaluations and recomendations from the TOI Owners Group Program applicable to Comanche Peak, Unit 1 and the licensee's actions in response' to this program for the Train A and B diesel generators, shall be submitted for the NRC review and approval before plant restart -
from the first refueling outage.
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4.0 CONCLUSION
The NRC staff concludes that the TDI diesel engines at CPSES Unit I will provide a reliable standby source of onsite power in accordance with General Design Criterion 17. This finding is based upon the NRC staff /PNL review of (a) the current status of the TDI Owners Group Program in resolving the TOI diesel engine issue; (b) actions taken by the applicant to enhance and verify the reliability of the Train A and B engines, (c) an acceptable Augmented Engine Maintenance and Surveillance Program as identified in Section 3.3 of this SER, and (d) operating restrictions to ifmit future operation and testing of the engines to 185 psig BMEP. The finding is contingent upon successful completion of actions listed below and is subject to the license condition given in Section 3.4 which assures that Comanche Peak Unit I will continue to meet GDC 17 beyond the first refueling outage. Items requ. ired to be submitted prior to exceeding 5*. power-are viewed by the staff to be confinna-tory in nature since the results, when submitted, are not expected to alter present staff conclusions. In many instances, preliminary results at CPSES Unit 1 or information obtained from other sites. indicate that these results will prove to be satisfactory when completed.
In the August 15, 1984 submittal, th'e applicant has identified items to be completed prior to fuel load. The applicant has subsequently modified its consnitment such that the following items now will be completed prior to fuel load:
- 1. Crankshaft main journal hole inspection for both engines.
- 2. Torsiograph test for one engine.
- 3. Evaluation by the Owners Group of the TDI recomendation for running of crankshafts for 15 min. at 150 rpm following each major overhaul, in light of Owners Group reconsnendation to run at 450 rpm at all times.
4 Review by TUGCo of an additional Phase 1 supplementary report by the Owners Group on cylinder block strain gage testing on Train A at CTSES.
- 5. Review by TUGCo of an additional Phase 1 supplementary report by the Owners Group cylinder block metallurgical testing at all sites.
- 6. Establishment of CPSES Unit I cylinder block top eddy-current inspection intervals based on (5).
- 7. Instaliation of shrouded SAE-1010 high pressure fuel oil injection tubing for both CPSES engines.
- 8. Eddy-current testing of this tubing.
- 9. High pressure fuel oil tubing support modification.
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J 10. Review by TUGCo cf an additional Phase 1 supplementary report by the Owners Group on connecting rod strain gage testing at another site.
' 411. Evaluation of CPSES connecting rod inspection requirements based on (1).
- 12. Modification of turbocharger lube oil drip systems to TDI recomendations.
- 13. Replacement of 16 remaining original exhau'st manifold bolts on Train B with new TDI socket head . type bolts.
14 Replacement of pneumatic tubing for engine protective functions w/
stainless steel tubing. ' '
- 15. Re-evaluation by the Owners Group of the recomendation for destructive -
testing of pushrods on a sample basis.
- 16. Detailed evaluation of CPSES preoperitional testing (to be documented in a ' supplemental report tnat includes items described in Section 3.2).
- 17. Material verification of rocker arm and airstart valve capscrews, The applicant has also comitted to complete the following prior to exceeding 5% power:
A
- 18. Recording of exhaust temperature at turbocharger inlet relative to e manufacturer's recomended maxiumum.
- 19. Visual inspection of newly installed fuel oil injection tubing for leaks during engine operation of both engines.
- 20. Review by Texas Utilitie:S of an additfonal Phase i supplementary report g by the Owners Group on design review of turbocharger vanes and capscrews.
The staff concurs with this comitment by the applicant. The results of items 1, 2, 3, 4, 5, 6,10,11,15,16,18, and 20 should be reported so the staff and receive staff approval prior to exceeding 5% power.
I The applicant should confirm to the staff,that items 7, 8, 9, 12, 13, 14, 17,
,j and 19 have been perfonned as comitted to. \
Additionally, the staff will require that the following infonnation be provided:
- i. Final disposition of #3 bearing saddle indication; bases for conclusions reached on saddles 1 and 9. ,
- 2. Hot and cold crankshaft deflection relative to TDI specifications.
- 3. Cylinder liner material verification.
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Final evaluation of TUGCo investigation of the fuel injection pump failure on Train A.
- 5. Revised maintenance / surveillance program to satisfactorily address the following items:
- a. Engine base / engine block
- b. Connecting rods
- c. Pistons
- d. Cylinder heads
- e. Studs and fixtures
- f. Crankshaft deflection checks
- g. Main bearing shells
- h. Connecting rod bearing shells
- 1. Cylinder liners J. Jacket water pump
- k. lube oil checks
- 1. Exhaust temperature, inlet to turbo
- m. Intake manifold air pressure
- n. Intake manifold air temperature
- o. Visual inspection for leaks
- p. Keepwarm oil filter p during standby
- q. Jacket water test for pH, conductivity, corrosion inhibitor
- 6. Inspect starting air distributor on Train B engine for excessive wear.
- 7. Final disposition of block indications that are formally under review by the Owners Group.
Prior to exceeding 5% power, items 1, 4, 5, and 7 must be submitted to the staff and receive staff approval and items 2, 3 and 6 should be confirmed as having been completed with satisfactory results.
The staff will require that the following items be provided and approved by the staff prior to fuel load:
- 1. Operating procedures to include a precautionary note to the operator to ensure that loads will not be added unnecessarily to the engines which cause the 18; psig BMEP to be exceeded.
- 2. Plant Technical Specifications to limit engine surveillance tests to within 25% of the nominal engine load where the upper limit of this load range corresponds to a BMEP of 185 psig (5740 kw).
- 3. Revisions to the FSAR, as appropriate, to demonstrate that the maximum emergency service load requirements for the diesel generators are within the 5740 kw load limitation.
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. PNL.5234
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"..- . . .. . Review and Evaluation of . . .
Transamerica Delaval, Inc.,
Diesel Engine Reliability and Operability - Comanche Peak Steam Electric Station Unit 1
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PNL-5234 Technical Evaluation Report REVIEW AND EVALUATION OF TRANSAMERICA DELAVAL, INC.,
0!ESEL ENGINE RELIABILITY AND OPERABILITY - COMANCHE PEAK STEAM ELECTRIC STATION UNIT 1 Septemoer 1984 Prepared .for tne U.S. Nuclear Regulatory Commission Division of Licensing Office of Nuclear Reactor Regulation under Contract DE-AC06-76RLO 1830 NRC FIN 82963 .
Project
Title:
Assessment of Diesel Engine Reliability /Operacility NRC Lead Engineer: C. H. Berlinger Pacific Northwest Laboratory Ricnland, Washington 99352 9
PACIFIC NORTHWEST LABORATORY PROJECT APPROVALS l
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. , Date , /C,/7Th-W. W. Laity, Project Manager [
Pacific Northwest Laboratory AY - YW Date L $ Ll W. O. Richmond, Chairman O Senior Review Panol i Pacific Northwest Laboratory m
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i FOREWORD This report is supplied as part of the Technical Assistance Project, Assessment of Diesel Engine Reliability / Operability, being cor. ducted for the U.S. Nuclear Regulatory Comission, Office of Nuclear Reactor Regulation, Division of Licensing, by the Pacific Northwest Laboratory. The U.S. Nuclear Regulatory Comission funded this work under authorization B&R 20-19 40 42-1 FIN No. 82963.
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1 CONTENTS FOREWOR0................................................................. v ABBREVIATIONS ANO INITIALISMS............................................ xiii
1.0 INTRODUCTION
....................................................... 1.1 1.1 ORGANIZATION OF REPORT ..................'........'.............. 1.2 1.2 LIMITED APPLICA81LITY OF CONCLUSIONS .......................... 1.2 1.3 REPORT PREPARATION ............................................ 1.3 2.0 BACXGROUND ......................................................... 2.1 2.1 OWNERS' GROUP PROGRAM PLAN .................................... 2.1 2.2 COMANCHE PEAK STEAM ELECTRIC STATION .......................... 2.3 3.0 PHASE 1_ COMPONENT PROBLEM RESOLUTION ............................... 3.1 3.1 TUGC0 PHASE 1 INSPECTION ..................................... 3.1 3.1.1 In s pect i on Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 3.1.2 Results/TUGC0 Conclusions .............................. 3.2 3.2 PNL EVALUATION ................................................ 3.3 3.2.1 En g i n e Ba s e a n d Be a ri n g Ca p s . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 3.2.2 Cy l i n d e r Bl o c k . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 3.2.3 Crankshaft ............................................. 3.9 3.2.4 Co n n ec t i n g Rod s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.13 3.2.5 Connecting Rod Bea ri ng Shel l s . . . . . . . . . . . . . . . . . . . . . . . . . . 3.19 i
. 3.2.6 Pi s t on Sk i rt s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.22 3.2.7 Cy l i n d e r Li n e r s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.24 3.2.8 Cy l i n d e r He a d s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.27 3.2.9 Cylinder Head Studs .................................... 3.29 3.2.10 Pu s h R o d s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.31 vii .
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3.2.11 R o c k er Arm Ca p s c r ews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.33 l
-3.2.12 Turbochargers ......................................... 3.34 1
- 1 3.2.13 Ja c k e t Wa t e r Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.38 i l
3.2.14 Hi gh-Pres sure Fuel Oil Tubi ng . . . . . . . . . . . . . . . . . . . . . . . . . 3.40 1 3.2.15 Ai r St a rti ng Va l v e Ca psc rews . . . . . . . . . . . . . . . . . . . . . . . . . . 3.41 3.2.16 Engi ne-Mount ed El ectri cal Cabl e . . . . . . . . . . . . . . . . . . . . . . . 3.42 4.0 PHASE 2 COMPONENT R EQUAL IF ICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 4.1 TUGC0 PHASE 2 PROGRAM INSPECTION .............................. 4.1 4.1.1 Inspection Procedures .................................. 4.1 4.1.2 Results/TUGC0 Conclusions ....................*.......... 4.1 4.2 PNL EVALUATION ................................................ 4.4 4.2.1 Methodology ............................................ 4.4 4.2.2 Fi ndi ngs and Concl usi ons . . . . . c. . . . . . . . . . . . . . . . . . . . . . . . . 4.4 l
5.0 Pit 0 POSED MAINTENANCE, INSPECTION AND SURVE!LLANCE PROGRAM .......... 5.1 5.1 MAINTENANCE AND INSPECTION PLAN ............................... 5.1 5.1.1 El eme n t s a nd Ra t i o n a l e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2 0
5.1.2 PNL Evaluation and Recommendations ..................... 5.2 5.2 OPERATIONAL SURVEILLANCE PLAN ................................. 5.21 5.2.1 El eme n t s a n d Ra t i o n a l e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.21 5.2.2 P NL Ev a l u a t i o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.21
,5. 3 STAN08Y SURVEILLANCE PLAN ..................................... 5.23 5.3.1 El eme n t s a n d Ra t i o n a l e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.23 5.3.2 PNL Evaluation ......................................... 5.25 5.4 PNL CONCLUSIONS ...................... ....................... 5.25 6.0 ENGINE TESTING ..................................................... 6.1 6.1 TUGC0 REPORTED POST. INSPECTION TESTING ........................ 6.1 viii 0
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6.1.1 PNL Evaluation ......................................... 6.2- !
6.1.2 P NL Co n c l u s i o n s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3 6.2 REVIEW AND EVALUATION OF ENGINE STARTS ........................
6.4 7.0 OVERALL CONCLUSIONS ................................................ 7.1 7.1 GENERAL CONCLUSIONS ........................................... 7.1 3 7.2 LONG. TERM APPLICA81LITY ....................................... 7.1 7.3 LICENSING CONSIDERATIONS ...................................... 7.2 7.3.1 General Cons i derati ons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ^7.2 7.3.2 TUGC0 Open Items Identi fi ed and Addressed . . . . . . . . . . . . . . 7.3 7.3.3 Other TUGC0 Ident i fi ed Open It ems . . . . . . . . . . . . . . . . . . . . . . 7.5 7.3.4 Open It ems Rai sed by the PNL Revi ew . . . . . . . . . . . . . . . . . . . . 7.5 t
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TABLES 4.1 Phase 2 Component Inspection Results ............................. 4.2 4.2 Defective Components That Could Significantly Affect Engine Operability / Reliability .......................................... 4.5 4.3 Defective Components That Will Not Significantly Affect Engine Operability / Reliability .......................................... 4.7 5.1 Comparison of TUGCO's Proposed Maintenance Plan: Items that Shoul d Se Incorporated Into TUGCO's Pl an . . . . . . . . . . . . . . . . . . . . . . . . . 5.3 5.2 Comparison of TUGCO's Proposed Maintenance Plan: Items to be Cons i dered in Estab li shi ng TUGCO's Pl an . . . . . . . . . . . . . . . . . . . . . . . . . . 5.8 5.3 Diesel Engine Operating Surveillance Parameters and Frequency .... 5.22 5.4 Diesel Engine Standby Surveillance Parameters and Frequency ...... 5.24 6.1 Preo p e ra t i o n a l Te s t Re s u l t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 0
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ABBREVIATIONS AND TNITIALISMS BMEP brake mean effective pressure CPSES Comanche Peak Steam Electric Station OR/0R design review / quality revalidation EDG, EDGs emergency diesel generator (s)
ESF engineered safety feature FaAA Failure Analysis Associates LOCA loss-of coolant accident .
LOOP loss of offsite power M/S maintenance / surveillance NDE nondestructive examination NRC U.S. Nuclear Regulatory Commission OG Owners' Group; the TOI Diesel Generator Owners' Group OGPP Owners' Group Program Plan 0/R operability and reliability PNL Paci fic Northwest Laboratory SWEco Stone & Webster Engineering Corporation TOI Transamerica Delaval, Inc.
TER technical evaluation report TUGC0 Texas Utilities Generating Company xiii
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c REVIEW AND EVALUATION OF TRANSAMERICA DELAVAL, INC., O!ESEL ENGINE RELIABILITY AND OPERABILITY -
COMANCHE PEAK STEAM ELECTRIC STATION UNIT 1 1
1.0 INTRODUCTION
Texas Utilities Generating Company '(TUGCO) has requested an operating Itcense for its Comanche Peak Steam Electric Station (CPSES) Unit 1. One matter eefore the U.S. Nuclear Regulatory Commission (NRC) in considering this request is the operability and reliability (0/R) of the station's standby emergency diesel-engine generators, which have been crougnt into question by a numeer of circumstances (as described in Section 2.0). The subject engines were manufactured by Transamerica Delaval, Inc. (T0!).
To identify, evaluate, and correct these concerns, TUGC0 has undertaken a number of investigative and corrective efforts. These have been addressed ey TUGC0 in several documents and related meetings witn NRC staff and NRC's consultant, Pacific Nortnwest Laboratory (PNL).* PNL has been requested by NRC to review and evaluate these documents and TUGCO's underlying ef forts. This technical evaluation report (TER) expresses PNL's conclusions and recommenda-tions regarding the operacility/ reliability of TUGCO's TOI standby emergency generators to serve U1eir intended functior..
Comanene Peak Steam Electric Station Unit 1 is served by two standby engines to meet its emergency service loads. Each is a TOI OSRV-16-4 engine, nameplate rated by TOI at 7000 kW, operating at 450 rpm witn a brake mean effective pressure or BMEP (a computed measure of the average cylinder pressure in the firing stroke) of 225 psig. TUGC0 has designated these engine-
- generators as Train A and Train B. The latest information provided by TUGC0 specifies the emergency loads for these engines as a maximum of 4200 kW for Train A and 4350 kW For Train B under_ design basis accident conditions coincident with a simulated loss of offsite power.
1.1
1.1 ORGANIZATION OF REPORT This technical evaluation report is organized as follows:
. Section 2.0 provides relevant background information on the known problems and efforts toward their resolution by both TUGC0 and an -
ad hoc group of similar TOI engine owners (the TDI Owners' Group) who have united their efforts in regard to these mutual considerations.
e Section 3.0 presents a review and evaluation of TUGCO's resolution of component probless that have been designated by the Owners' Group (OG) as generic (tenned Phase 1 component problems).
. Section 4.0 presents a review and evaluation of TUGCO's identifica-tion and resolution of other component problens (termed Phase 2 component problens) pertinent to the engines at CPSES.
e Section 5.0 documents PNL's evaluation of TUGCO's preoperational testing plan and results.
e Section 6.0 presents PNL's review of the utility's proposed maintenance and surveillance (M/S) program.
e Finally, Section 7.0 presents PNL's overall conclusions and recom-mendations regarding the suitability of the two diesel engines to perform their intended function as emergency standby power sources for the CPSES Unit 1.
1.2 LIMITED APPLICABILITY OF CONCLUSIONS PNL has reviewed the basic documents referred to in Section 2.0, has participated in various meetings with TUGC0 and NRC, and has observed com-ponent,s of the Train B engine as disassembled in TUGCO's inspection program.
Concurrently, PNL also has reviewed various relevant Owners' Group documents and participated in their meetings with NRC, and has completed TERs on some elements of the Owners' Group Program Plan (0GPP).
This TER on the CPSES Train A and Train B engines' operability and reli-ability precedes completion of the OGPP and its appropriata implementation by l TUGCO. This document also precedes the OG planned full plant-sp6cific design 1.2 l
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review / quality revalidation (OR/0R) analyses of both the Train A and Train B
- engines. Therefore, PNL is constrained from reaching unlimited conclusions relative to the CPSES Train A and Train B engines' operability and reliability to perform indefinitely their expected design function. PNL conclusions are subject to full completion of all OGPP and TUGC0 DR/QR programs and implementation of their findings (PNL feels these actions should be a part of TUGCO's licensing autnorization).
Hence, PNL has evaluated all components in light of expected operating conditions and patterns at CPSES over a period of tine corresponding to the first reactor refueling outage, wnich PNL understands to be approximately 18 months from initial plant startup. By that time, all phases of both the general OGPP evaluation and implenentation and the plant-specific CP5ES OR/OR program snould be complete and ready to implement. Because these actions will
, represent proposed resolution of the TDI engine issues at CPSES, PNL will make its final conclusions regarding the long-term operability / reliability of tne CPSES engines at that time.
The considerations and recommendations presented in this TER are sometimes expressed in terms of "until the first reactor refueling outage." However, in using this pnrase, PNL does.not intend to imply (unless specifically stated otherwise) that the engines or their components are therefore unreliable or inoperable for their intended use over their normally expected life.
1.3 REPORT PREPARATION j As stated, tnis report is based in part on a review of documents cited in
, Section 2.0. The PNL team also visited the CPSES on May 24 and 25,1984, wnile j the Train B engine was disassembled for inspection. At that time many of the
" generic" components of that engine (identified by the Owners' Group as Phase !
iss'ues) were visually examined, and the TUGC0 disassemely, inspection, and 4
' replacement parts records were reviewed for botn Train A and Train B. At that time the PNL team, together with NRC, also met with appropriate TUGC0 staff and management concerned with diesel engine operability / reliability.
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The following PNL staff members and consultants were involved in this review and evaluation, and authored P.nis report:
e D. A. Dingee, PNL project staff e B. J. Kirkwood, Covenant Engineering, diesel consultant to PNL e J. E. Horner, Seaworthy Systems, Inc., diesel consultants to PNL e H. M. Hardy, diesel consultant to PNL.
Others whose contributions were considered in formulating the conclusions include PNL Assessment of Diesel Engine Reliability / Operability Project team members J. M. Al zheimer , M. Cl ement , S. D. Dahlgren , R. E. Dodge , W. W. Lai ty ,
J. F. Nesbitt, J. C. Spanner, and F. R. Zaloudek; and consultants S. H. Bush, A. J. Henriksen, P. J. Louzecky, A. Sarsten, and J. A. Webber (representing Ricardo Consultir.g Engineers ple). Th,e report editor was A. J. Currie.
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2.0 BACKGROUNO This section presents background information on efforts uncertaken by tne TOI Diesel Generator Owners' Group and by Texas . utilities Generating Company to resolve the problems identified in the TOI diesel engines.
2.1 OWNERS' GROUP PROGRAM PLAN Thirteen nuclear utilities that own diesel generators manufactured by Transamerica Delaval, Inc. (TOI), have established an Owners' Group to address questions raised by a major failure in one TOI diesel engine (at the Shorenam Nuclear Power Station in August 1983), and other problens in TOI diesels reported in the nuclear and non-n'uclear industry. - On Maren 2,1984, the Owners' Group submitted a plan to the U.S. Nuclear Regulatory Connission out-lining a comprenensive program to requalify tnete diesel generator units for standby emergency power.
The Owners' Group Program Plan specifies a utree-stage approacn to resolving tne known and potential problems:
e Phase 1 is an in-depth analysis of the core group of 16 known
" generic problem" components identified by a review of the operating history of TOI engines in nuclear and non-nuclear service. Th e Phase 1 analysis provides a determination of the operating history witnin tne general population of these engines, the apparent cause j (or causes) of problems, and methods for achieving their satisfactory
] resolution. Phase 1 of the OG Program Plan is pertinent to all nuclear utility TOI diesel engine owners.
e Phase 2 is a comprehensive design review / quality revalidation (OR/OR)
' process to address all other significant components of the engine l , system, to ensure that they, too, are reliably operable for the intended safety function of these engines. In cooperation with the utility members, the Owners' Group is identifying a number of compo-nents for each engine that should be inspected, and is providing an j
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inspection plan and acceptance criteria. PNL understands that CPSES has been supplied this Phase 2 information for their Train A and 8 engines.
e The third stage is a program of further testing and surveillance and maintenance. Testing and inspection are intended to help identify and evaluate the problems, both initially and at appropriate future intervals. The surveillance and maintenance procedures, enhanced beyond that dich is " customary", are meant to prevent or to identify future problems before they appear.
At NRC's request, PNL reviewed the Owners' Group Program Plan. The results of that evaluation were reported to NRC in PNL-5161, Review and Evaluation of TOI Diesel Generator Owners' Group Program Plan (Pacif. .
Northwest Laboratory June 1984).
Section 4 of PNL-5161 deals with considerations for interim licensing of nuclear stations prior to completion of the implementation of the Owners' Grouc
! Program Plan. Recommendations in that report relevant to TUGCO's license for the Comanche Peak Steam Electric Station at this time are:
- 1. The engine should have AE pistons or complete " lead-engine" tests as described in Section 2.3.2 of PNL-5161. (Confirmed in Section 3.7.4 herein.)
- 2. The diesel generator should not be required to carry a load in excess of enat corresponding to an engine brake mean effective pressure (BMEP) of 185 psig. (Confirmed in Sections 6.1.1.)
- 3. The engine snould be inspected per Section 2.3.2.1 of PNL-5161 to assure that the components are sound. (Confirmed in Sections 3.0 ano 4.0.)
4 Preoperational testing should be performed as discussed in Sec-tion 2.3.2 of PNL-5161. (Confirmed in Section 6.1.)
- 5. The engines should receive enhanced surveillance and maintenance.
(Discussed in Section 5.0.)
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f The significance of Recommendation 1, .the AE piston skirts, is tnat 7
relevant service experience (10 cycles) exists to provide empirical support of 4
satisfactory analytical results. Recommendation 2 derives from tne fact tnat this experience is at a level corresponding to the BMEP limit of 185 psig.
Also, pending evaluation and approval of Owners' Group reports addressing ,
crankshaft stress levels at higher loads, _PNL considers the load corresponding to 185 psig BMEP to be reasonably conservative for the crankshaft. In addi-tion,- because of open items in the implementation of the Owners' Group Program Plan, an adequate basis does not yet exist to provide reasonable assurance that
, T0! diesel engines would operate reliably in nuclear service at power levels l higner than those corresponding to a BMEP of 185 psig.
4 The other three recommendations are self-evident, namely that the engine has sound parts, that appropriate preoperational tests have been satisfactorily completed, and that a suitable program of_ surveillance and maintenance is estaolished to assure future performance.
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2.2 COMANCHE PEAT STEAM ELECTRIC STATION >
j in their efforts to establish the operability and reliability of CPSES 701 diesel engines, TUGC0 has conducted a aamber of tests and inspections and has provided NRC with relevant letters and reports. Items consioered in this Tecnnical Evaluation Report are listed below.
1 e A letter dated April 30, 1984, from J. B. George (TUGCO) to H. R. Denton (NRC), " Comanche Peak Steam Electric Station Diesel Generator Requalification Program Plan." This document and '
- attachment discuss diesel generator performance experience at CPSES and actions taken to enhance reliability. The testing and inspection l -
program underway at CPSES is also outlined.
- e A letter dated June 7,1984, from J. B. George (TUGCO) to
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l T. A. Ippolito (NRC), "CPSES Unit 1 Train A Diesel Generator Inspection Results." This document provides NRC with the Train A inspection results following engine disassembly in February and Maren 1984 2.3 I
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e A letter dated June 19, 1984, from B. J. Youngblood (NRC) to M. D. Spence (TUGCO), "TOI Diesel Generator Reliability Verification Required for the Licensing of the Comanene Peak Steam Electric Station, Unit 1." This document identifies plant-specific actions that must be taken by TUGC0 prior to NRC licensing of CPSES. ,
e A letter dated June 29,1984 from J. 8. George (TUGCO) to T. A. Ippolito (NRC), "CPSES Unit 1 Train 8 Diesel Gentrator Inspec-tion Results." This document provides NRC with the Train B inspec-l tion results following engine disassembly in February and Maren 1984
- A letter dated August 1,1984, from J. B. George (TUGCO) to B. J. Youngblood (NRC), "CPSES Diesel Generator Preventive Maintenance / Surveillance Schedules and TUGC0 Responses to the Phase 1 Recomendations of the TOI Diesel Generator Owners' Group."
e A letter dated August 2,1984, from B. J. Youngblood (NRC) to M. D. Spence (TUGCO), "TDI Diesel Generator Reliability Verification
! Required for the Licensing of the CPSES Unit 1." This document pro-vides details of items to be included in TUGCO's future submittals.
It also supplied TUGC0 with a TOI maintenance / surveillance program approved by the NRC staff for the Grand Gulf Nuclear Station.
'e A letter dated August 15, 1984, from J. B. George (TUGCO) to
! B. J. Youngblood (NRC), "Comprenensive Report on the CPSES Diesel
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Generator Requalification Program for Unit 1." This report provides details on the OR/QR done to date. It summarizes the results of the engine inspections, proposes a surveillance and maintenance program, describes CPSES diesel generator quality assurance activities, and sets out verification procedures to assure that the maximum emergency service loads are in compliance witn a 185-psig BMEP limit.
> e A letter dated August 17,1984, from J. 8. George (TUGCO) to B. J. Youngblood (NRC), " Errata Sheet for Comprenensive Report on tne CPSES Diesel G...erator Requalification Program for Unit 1." This errata sheet provided 14* changes to the August 15, 1984, submittal.
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3.0 PHASE 1 COMPONENT PROBLEM RESOLUTION This section documents PNL's evaluation of TUGCO's efforts to identify anc
- resolve site-specific problems noted with the 16 generic components. These components had been identified by the Owners' Group in Phase 1 of tne OGPP
' implementation.
The overall TUGC0 inspection process is reviewed first. Then PNL's review, evaluation, and conclusions regarding TUGCO's component problem resolu-tion efforts are described. It is very important to note that PNL's conclusions incorporate, generally without stating, TUGCO's commitment to the surveillance and maintenance program described in Section 5.0 of this TER, as well as tne utility's comitment to implement, as appropriate, the apo11 cable recommendations of the OG as soon as practicable.
3.1 TUGC0 PHASE 1 INSPECTION TUGC0 began the Phase 1 inspections after each emergency diesel generator (EOG) had been operated for only approximately 92 nours. This total included tne TOI shop runs of about 7 nours on each engine plus the required preopera-tional testing at CPSES.
3.1.1 Insoection Procedures TUGC0 disassemoled eacn EDG, removing all parts normally disassembled for o vern aul . This left intact the engine base, crankcase, cylinder blocks, crank-snaft, and gearing (plus miscellaneous otner components attacned tnereto, some of whicn were themselves inspected in place). Detailed inspections were per-formed on all but two Phase 1 components, on eacn engine. (Those are discussec
, below.) Additionally, some 45 Phase 2 components were inspected (some from only one of the two engines). Visual inspection, dimensional checking, and testing by material comparator, liquid penetrant, magnetic particle, ultra-sonic, radiograpny, and eddy-current techniques were utilized, all to criteria established by the OG (where available) or to criteria thougnt by TUGC0 to be conservative were Owners' Group criteria did not exist or were not fully detailed. Records were maintained for each part (or group); these records were 3.1
then subjected to a process of review, evaluation, and disposition, which was designed to maintain quality control.
The same procedures used for inspection and evaluation of the disassemoled components were, in general, applied to all replacement parts (e.g., AE skirts, push rods, cylinder heads). Furthermore, TUGC0 reports they have establisned enhanced onsite QA/QC oversight procedures it TDI's plant so that all future parts of significance will be adequately sur. eyed and the documentation checked before the parts leave that. plant.
The decision to thorougnly disassemble and inspect both engines was made by TUGC0 in early 1984, to be done in conjunction with the process of replacing the original AH piston skirts. -(This was decided after an evaluation of them snowed they were quite similar to the AF skirts about which serious questions on 0/R had been raised within the industry.) This meant that some component inspection and quality control criteria were necessarily estaolished locally, anead of determinations on such itees by tne OG. However, TUGC0 staf f communicated with the OG staff on such items so as to both make and receive .
input constructive to the process.
3.1.2 Results /TUGC0 Conclusions A detailed description of TUGCO's Phase 1 inspection results is presented in Comprenensive Report on CPSES 01esel Generator Requalification Program for Unit 1 (George August 15, 1984). Based on those results, TUGC0 concluded (p. 69) that:
- 1. The CPSES Unit 1 TDI diesel generators are adequate to perform their.
intended function. .
- 2. Licensing of CPSES Unit i for first cycle operation is permissible .
wnile the remaining diesel generator open items in (their] report are being accomplished prior to fuel load.
The TUGC0 report also noted that these two EDGs were purchased, manuf ac-tured, shipped, and installed at virtually the same time. Startup was roughly concurrent and, when disassembled, both had operated about the same number of
, hours . Inspection of Train B lagged that of Train A'by a matter of only a few weeks. As noted previously, virtually the same inspections were mace on eacn, 3.2
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s the exception relating mostly to the Phase 2 components. Identical enangeouts were made to the as-received " generic component" itens of piston skirts, cylinder heads, head studs, electrical cable, and push rods, all of wnich were inspected to the same sets of standards. All other components (such as turbocharger parts, bearings, and valves) replaced on an as-needed basis were checked against applicable T0! and OG standards.
3.2 'pML EVALUATION PNL's review of TUGCO's Phase 1 component requalification ef forts is documented in this section. Each generic problem component is discussed individually. The components are presented in a sequence reflective of their location within, on, or about tne engine. The sequence generally progresses from bottom to top (that is, structural components, power train components, ancillary and auxiliary systems and comconcnts, on-engine and then off-engine).
The components are described in terms of their function, operating history, and status as determined by the Owners' Group and TUGCO. Then, PNL's evaluation and conclusion (s) are presented for each component.
3.2.1 Engine Base and Bearing Caos .
Part No. 02-0305A-0 Owners ' Group Report FaAA-84-6-53 3.2.1.1 Component Function The base itself supports the cranksnaft and upper structures anc carries the thrust of the cylinder comeustion loads. The shaft is bedded in nalf-circle bearings set witnin " saddles" in the case. Die eearing caps are struc-tural members that hold the upper bearing snells in place over the shaft main jou,rnals wnile also aesorbing the upward, reciprocating piston inertial loads. The studs and nuts hold the cap (and snaft) in place. A failure of base, cap, or bolting would allow shaft motion or misalignment, potentially leading to shaft fracture and seizure, sudden engine stoppage, and possible ignition of crankcase vapors (termed crankcase explosion).
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3.2.1.2 Component Problem History Two basic problens have occurred that warranted OG evaluation of tnis component as a generic Phase I issue:
e Saddle structures were found to be cracked in one engine base (an inline OSR4-8 engine) at Long Island Lighting Company's Shoreham Nuclear Power Station.
e On a non-nuclear application of a OSRV-16-4 engine a nut pocket failed on the through-bolting from tne crankcase.
3.2.1.3 Owners' Group Status Failure Analysis Associates (FaAA), as discussed in the Owners' Group report, has analyzed the' base, bearing saddles, bearing caps, nut pockets, and bolting / nuts. FaAA has concluded that tne base assemoly components nave tne strength necessary to operate at full rated load for indefinite periods, provided tnat all components meet manufacturer's specifications, that they have not been damaged, that mating surf aces are clea,n, and that proper bolt preloads are maintained. They concluded that the failed nut pocket was due to impuri-ties in the casting material. The pattern of saddle fractures at Shoreha:n was determined to be related to improper procedures in disassemoly. The OG/c aAA report has not been finally evaluated by PNL to this date, pending resolution of several matters.
- 3. 2.1.4 TUGC0 Status There have been no instances of failure or evident deficiency on CPSES Train A or 8. Saddle and cap surfaces of both Train A and B were inspected visually and witn liquid penetrant. There were no indications at all en Train B, nor on Train A caps. On Train A, however, there were linear indica-tions-on the journal Nos.1, 3 and 9 bearing saddles. All were reported to the Owners' Group. Nos.1 and 9 were evaluated as minor, acceptacle casting flaws.
The indication at No. 3 remains under TUGC0 and OG evaluation. No cause was set forth by TUGC0; they report, however, that the preliminary conclusion drawn by the OG from fracture mechanics analysis is that there is a large factor of l
l safety against propagation. Further, the OG gave conditional release to permit l reassemoly and preoperational testing.
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i According to TUGCO, material and dimensional characteristics will be documented in the Phase 2 report on CPSES engines.
I The engines were reassembled in accordance with requirements on cleanliness and bolt torque. TUGC0 contends the components are adequate and ready for their intended nuclear standby service.
3.2.1.5 PNL Evaluation and Conclusion" There is no indication of widespread, generic failure in bases or caps of TDI V-16 engines, either in general or at CPSES. Hence, there is no basis for fundamental concern at CPSES at this point. However, TUGC0 should fully docu-ment its engineering disposition and technical justification of the indications found on the No. 3 bearing saddle for Train A. This should include the bases for its finding that there exists a large factor of safety against crack propa-gation. If the engineering disposition includes provisions for enhanced surveillance, this should also be documented. This documentation should be provided before final conclusions can be reached be PNL regarding acceptability of Train A for one refueling cycle operation.
With regard to Train B. PNL concludes that TUGC0 has provided satisfactory evidence that the Train B engine base and associated components are free of deleterious indications. Thus, PNL believes they are acceptable for their intended EDG service.
3.2.2 Cylinder Block Part No. 02-315A Owners' Group Report FaAA-84-5-4 3.2.2.1 Component Function Cylinder blocks (with their associated cylinder liners) contain the pistons. They are bolted to the vee-engine crankcase. The cylinder heads are bolted to the blocks; hence, the blocks are subject to the power forces from the cylinders. They also support the camshaft and other miscellaneous compo-nents and serve as the outer containments for the jacket water system. Depend.
ing upon its nature and location, a structural failure can lead to inadequate 3.5 m
support of the primary combustion and mechanical forces, with concomitant sudden engine shutdown.
3.2.2.2 Component Problem History Several incidents of cylinder block cracking have been reported in non-nuclear TOI engine applicatio'ns. In nuclear service, indications have been reported to date on engines at Shoreham and Comanche Peak. None has resulted in emergency shutdown or catastrophic failure. A number of engines have continued to operate many hours with known cracks.
Two basic problems have occurred that warranted OG evaluation of blocks as a generic Phase ! issue:
< 1 Support,s for the camshaft were found cracked in Shorenam's inline engines.
e Cracks nave been found in tne upper reacnes of various blocks. Mos I have been on the top surf ace, between the cylinder liner opening ano aojacent head stud openings (ligament cracks); some, however, have been between stud openings in adjacent cylinders. At Comanche Peak
" vertical" cracks have occurred in the area of the liner landings, but have not extended to the top surface. At least one instance of a circumferential1y oriented crack along the liner landing (support ledge) itself has been reported, in the V-16 engine at St. Cloud, Florida.
3.2.2.3 Owners' Grouo Status
, Failure Analysis Associates performed strain gauge testing comoined witn two-dimensional analytical modeling of block tops and liners. In their recort,
- FaAA concluded, in part
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- Eventually, depending upon a combination of sufficiently nign load and operating hours, and/or engine starts to hign load, cracks can be expected to initiate between stud hole and liner openings. However ,
such cracks are predicted to be benign (e.g., nonpropagating) if the block materials are free of deleterious materials and properly cast, and if engine loads therein remain below the nominal 225 psig BMEP 3.6 l
rating. FaAA notes that some engines (such as those at Duke Power Company's Catawba Nuclear Station) have operated many hours at loads at_and exceeding these levels without even initial crack indications. This is, in FaAA's opinion, indicative of the conservative nature of their evaluation, e The initial development of ligament cracks between the stud hole and liner opening will increase the likelihood of more serious cracks developing between stud holes of adjacent cylinders. Therefore. the Owners' Group has recommended that engine blocks with ligament cracks be inspected by the eddy-current technique prior to the engine's return to standby service after any period of operation above no load.
e The FaAA report implies that, if block material is equal to or better than typical Class 40 grey iron, is properly cast, and has no initial cracks between stud hoIes of adjacent cylinders, the block of a,ny er.gine can be expected to survive the service requirements of any LOOP /LOCA event (even to 225 psig BMEP).
The OG/FaAA report has not received full PNL evaluation to this date.-
However, PNL views FaAA's conclusions as reasonable and useful in evaluating the CPSES block for interim licensing actions. PNL has, however, expressed some concern over the effectiveness of eddy-current testing if cracks do not penetrate to the surface. '
3.2.2.4 TUGC0 Status Up to the time of disassembly and inspection, each CPSES engine had coer-ated approximately 92 hours0.00106 days <br />0.0256 hours <br />1.521164e-4 weeks <br />3.5006e-5 months <br />. This operating history is too short to provide an i .
adequate basis for evaluating fatigue experience of these engines. However ,
other V-16 engines with over 750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br />' service at loads exceeding 185 psig l
, BMEP have developed no cracks.
4 All liner landing areas were inspected by liquid penetrant. The entire top faces of all four blocks (e. h bank, each engine) were examined by magnetic particle methods. Eddy-current examination was conducted in the region between studs of' adjacent cylinders where experience with other engines indicates the l s 3.7 i
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potential for cracks. Certain indications also were examined under 10X pmagnification, and all liner landing areas were checked dimensionally.
Or. Trains A and B, all dimensions were satisfactory. In addition, all block faces were satisfactory, with no indications between stud holes nor to
. lineropenings.f
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On Train A,'threelllner lendings showed indications (not extending to the block surface). One was evaluated as "nonrelevant". . The other two remain
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under fo, mal evaluation by the OG; TUGC0 concludes from the OG generic report tnat, given ongoing monitoring, the block is serviceaole.
On Train B, three landings showed indications similar to those of Train A,
, plus various other minor marks (determined to be machining marks). Most were evaluated as rounded, nonpropagating, and acceptable. The others' were evalu-i ated as acceptable casting, shrinkages, but remain under OG investigation.
As noted, some aspects of these in'dications at CPSES remain under OG investigation and evaluation, including strain gauge monitoring of one Train A block.- (Resultt will be reported in a supplement to the Pnase 1 report and in j the CPSES Phase 2 reports (in progress).]
TUGC0 has committed to perform the block-top surveillance inspections t (visual and eddy current) recommended by the OG report when ligament cracks exist, even thougn TUGC0 contends the indications found are not ligament cracks. TUGC0 concludes that these blocks are adequate for nuclear standby service..
4 j 3.2.2.5 PNL Evaluation and Conclusion Ther2 is indication of cricking of cylinder blocks, in both nuclear and
~nc.n-nuclear service. Therefore, the nontypical indications at CPSES warrant '
sone attention.
In addition to the invedtigations and analyses already completed, TUGC0 nas cognitted to a program of monitoring its blocks, including eddy-current j . monitoring as reconnended by the 0..ars' Geoup when ligament cracks exist.
Furthermore, TUGC0 has committed to limit its EDG operations to loads no higher 1
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! than 185 psig BMEP (i.e., 82% of nameplate rating) until final conclusions regarding the OGPP are reached by PNL and NRC; its evaluated LOOP and LOCA l loads are well below 185 psig BMEP (the highest of which is 62% of engine rating, or 140 BMEP).
In light of the data provided, the conunitments made to monitor, and the site-specific load expectations, PNL concludes that the blocks--both Train A and Train 8--can be expected to operate reliably for their intended duty and can be placed in service at least through the first refueling cycle. The PNL concern regarding the inability of eddy-current to detect subsurface cracks is also mitigated by the TUGC0 comitments and engine load limits. This con-clusion is subject to confirmatory information regarding the strain gauge measurements of the Train A block.
3.2.3 Crankshaft
! Part No. 02-310A Owners' Group Report FaAA-84-4-16 3.2.3.1 gmoonentFunction The crankshaft receives the reciprocating power strokes from the cylinders (via the connecting rods), converts them to rotary motion, and transfers the shaft power to the generator. It also drives the gear trains for operating cylinder head valves, etc. The crankshaft is supported in journal bearings in the engine base. The shaft is of machined steel and forged to the appropriate configuration. In TDI vee engines, opposite pistons are connected to the same throw by an articulated master / slave connecting rod arrangement. By means of holes drilled throughout the shaft and shaft journals, oil is picked up from main journai bearing supply points and transmitted to connecting rod bearings, link pins, wrist pins and undersides of the pistons, and other parts. l The shaft is subject to a variety of complex stress fields resulting from o
the piston thrusts, inertial effects of rotating and reciprocating masses, !
torsional vibrations, bending forces due to variitions in support alignments, and stress fields reflective of oil heles, crankweb-to-journal interfaces, etc., as well as shaft material and fabrication influences, and operating con-
, ditions and accidents. The machined journal bearing surfaces are subject to e
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5 damage from oil impurities, bearing deterioration, an'd excessive heat. Fail-ure, therefore, can come in various ways. At its worst, a shaft may actually break, leading to immediate shutdown and possible sigd fhcant damage to numer-ous components. Other failures may evidence themselves less destructively and 5
- more gradually, and can sometimes be detected via monitoring, surveillance, and maintenance activities. However, generally speaking, significant occurrences are rare in engines of this general class (rating, speed, service).
Some of these incipient problems can be detected and avoided through periodic crankshaft deflection checks. These checks accomplish two basic purposes; e detection of gradual shifts in shaft support internal to the engine (e.g., significant bearing deterioration) e detection of changes in external engine support, as in the concrete foundation, loose foundation bcits, or a shift of shims between the foundation rails and the engine base plate.
l 3.2.3.2 Comoont ~t Problem History Three V-16 crankshaft failures have been reported, all in the.non-nuclear industry. Two failures were attributed to torsional stress due to operation too close to the critical speed. 'e cause has been suggested for the third failure. There also have been failures of shafts of other TDI R-.1 engine models, most notably ore broken and two cracked shafts at Shoreham. Because of the engine-specific. nature of shaft stresses, the Shoreham failure is not necessarily germane to V-16 engines in general nor to the Comanche Peak engines speci fically. However, it did signal a justifiable cause of concern on TDI engines.
l
,3.2.3.3 Owners' Group Status
- The Owners' Group undertook in-depth Phase 1 analyses of the inline-8 ,
shafts of Shoreham and the V-16 shafts at Mississippi Power & Light's Grand Gulf Nuclear Station. Only *.he latter are of similar design parameters and comparable operating conditions to the shafts at Comanche Peak. However, because of differences in generator and flywheel characteristics, the torsional 3.10 l
-stresses would be somewhat different at each plant. Hence, as part of the OG Phase 2 efforts, the CPSES shafts are being evaluated separately.
The OG analysis on Grand Gulf drew generally favorable conclusions on adequacy for their intended service, with certain provisos or cautions:
e Oil holes in certain main journals present the most critical tor-sional stress concentrations and should be inspected for machining discontinuities and fatigue cracks.
e Torsiograph testing should be done to establish or confirm torsional stresses.
Engines should not be run close to speeds considered harmonically critical (which, at Grand Gulf, was established as a 440 rpm lower limit).
PNL's review of the OG/FaAA report has yet to be finalized.
3.2.3.4 TUGC0 Status Upon disassemoly to the point of crankshaft accessibility TUGC0 performed visual inspections of all crankpin journals on both engines. One journal on Train A and one on Train B had minor scoring marks; the former was honed out, '
while the latter was deemed too minor to need attention.
Because initial indications from the Shoreham problem emphasized crankpin fillet areas as most critical, TUGC0 ran eddy-current examinations on seven crankpin journals of Train A and six on Train 8, with no relevant indications.
No examinations were conducted on main journals, nor at oil holes any-where.
(The latter OG requirement was published after the CPSES inspections were underway.)
- Hot and cold crankshaft deflection measurements were conducted on both
' engines following reassembly; they were completed within 40 minutes of shut-down. Results were reported in George (August 15,1984). No evaluations were presented, but TUGC0 has stated (and will confirm) they meet TDI standards.
TUGC0 has committed to the following actions:
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9 e One engine will be torsiographed, at 25, 50, 75 and 100% loads (based on 225-psig BMEP ratings). No definite schedule was stated, but TUGC0 has advised NRC it will be run the week of September 2,1984 ,
e Oil holes on the three main journals recommended by the OG will be inspected on each engine, prior to fuel loading at CPSES, and reported to NRC and others, e The engines will not be run below 450 rpm except at startup and shutdown.
Additionally, the Phase 2 DR/QR report will directly assess the design adequacy and quality of the shafts at CPSES (with, presumably, any appropriate adjust-.
ments to the above connitments).
On the basis of the OG analyses and conclusions on the Grand Gulf shafts, and with subject provisos outlined above, TUGC0 concludes the Train A and B l
snafts are satisfactory for nuclear standby service.
l 3.2.3.5 PNL Evaluation and Conclusions Based on its review of the information provided on the crankshaft, and subject to the following conditions, PNL concludes that the crankshafts for both the Train A and B engines are acceptable for service through the first refueling cycle, e Customary engine operations will be limited to loads at or below 185 psig BMEP. Because the anticipated LOOP /LOCA loads are evaluated by TUGC0 at 140 psig BMEP, this load limitation should not create safety concerns at CPSES Unit 1.
e The oil holes will be inspected prior to fuel loading per TUGC0 connitment, with satisfactory results.
e The torsiograph will be completed by the same time, prior to fuel loading per TUGC0 cannitment, with satisfactory results, e TUGC0 or OG evaluation of hot and cold .aaft-deflections, determined to be within TDI speci.fications, will be submitted.
3.12
3.2.4 Connecting Rods Part No. 02-340A Owners' Group Report FaAA-84-3-14 3.2.4.1 Comoonent Function Connecting rods transmit the power thrusts between the pistons and the crankshaft. They are of forged steel, either round or H-shaped cross section.
In TDI vee engines there are two types of rods. One is a master rod serving one bank, which is directly connected to the crankthrow (or crankpin) o'f the crankshaft. The other is the articulated link or slave rod, and is connected to the master rod via a link pin. The master rod lower end is split diagonally across the crankpin annulus. The mating surfaces, generally known as serrated
. joints, are machined as racks .(i .e., with gear-like teeth) and bolted together.
Rods can fail in various ways. Of greatest concern in these engines is the possibility of breakage in the " rod box" in the vicinity of the link pin
~
and/or failure of the bolts across the mating faces. Major failure will lead to instant damage to major parts of the engine. Lesser failures, as in the bearing support areas or link pin assembly, may lead to damage to bearings and journals, link or wrist pins, or even to piston' seizure or a loose connecting rod (with possible major damage to the engine).
3.2.4.2 Comconent Problem History Various connecting rod failures have been reported from the non-nuclear field. One failure mode was in the link-rod blade-to-pin bolting, due to loss of bolt preload. The other principal mode of failure was fatigue cracking of connecting rod Dolts and/or the link rod box in the area of the mating threads.
No connecting rod failures have occurred in nuclear service.
- 3.2.4.3 Owners' Grouo status In light of the problems in a few specific installations (nonnuclear), the OG undertook an in-depth evaluation of all known-potentialities. The OG determined that the loss of preload on bolting between the link rod and link pin stemmed from an incorrectly sized locating dowel. The dowel's excessive length prevented proper bolting contact between pin and rod. Under firing-load 3.13
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conditions the dowel would yield sufficiently in compression that the bolt preload would relax, with resultant fatigue problems. Replacement with dowels of proper length, followed by proper bolt preload, corrects the incipient problem.
The second failure mechanism was fatigue cracking of the cross-joint connecting rod bolts and/or the link rod box at the mating threads. TDI attributed these rod cracks to " thread fretting," which they concluded resulted from distortion of the rod bolt under operating loads in the area of the mating threads. The distortion could occur even if the bolts had been installed with the originally specified bolt preloads. The Owners' Group addressed this concern for the two versions of the connecting rod, namely the original design equipped with 1-7/8-inch bolts and a later design in which the rod boxes were equipped with 1-1/2-inch bolts. Stress analysis, including finite element studies, was done by FaAA. They concluded that both designs are adequate for the service intended, provided connecting rod bolt preload is regularly checked within specified time limits that are related to engine load requirement.
However, the rod with the 1-1/2-inch bolts was found to have an 8% to 9%
greater margin of safety than the rod with 1-7/8-inch bolts because the related rod-box structure is more massive with the smaller bolt configuration. The Owners' Group recommends inspection by eddy current of the rod box threaded hole. Implementation of this recommendation has so far proven to be impractical.
Another area of concern was that of possible sideways bo' wing of ne connecting rod, sometimes coming as a consequence of the forging process. FaAA computed the consequences and established a functional tolerance limit against which connecting rods should be checked.
The last area of possible failure was in the wrist pin (or piston pin) bushings, considered by TDI as a component of the connecting rod assemoly.
Several original and replacement bushings at Shoreham, in particular, were found to have indications on both inner and outer surfaces. FaAA evaluated these as interdendritic anomalies (casting defects), having little functional significance but best replaced where encountered.
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- 3.2.4.4 TUGC0 Status l l l TUGC0 performed comprehensive inspections and examinations of the connecting _ rods and related parts on both Train A and B engines during their complete disassembly. The results were reported in George (August 15, 1984).
A brief summary of those results follows. i For Train A: I e Visual-inspection revealed many areas of galling on bolts, studs, washers, nuts, and bolt holes.
e Liquid penetrant inspection of certain surface areas on the link rod box, inner diameter of box bushings, and rack surface areas were deemed satisfactory, except for linear indications found on all connecting rod-box external surfaces.
e Magnetic particle testing was done on all bolts and studs, with sati sfactory results reported.
e Eddy-current examination was conducted on " mating threads" (appar-ently meaning the female threads) of connecting rod boxes, with satisfactory results. (PNL subsequently reviewed this result in a
- telephone conversation with TUGC0 and NRC in view of the difficulty encountered at other engines in conducting eddy-current tests. TUGC0 agreed that the results were uncertain.)
e Material comparator and hardness tests were performed on all rods, rod-box areas, pins, and bushings, including spares, with satis-factory results.
e Dimensional check's of link pin locating dowels were all found to be satisfactory.
e Bolts were torqued to standards, using a calibrated hydraulic wrench.
The results for Train B were:
4 e Visual inspection revealed galling similar to that on Train A.
e Liquid penetrant inspection (on bushings only) revealed several areas of scoring.
3.15
e Magnetic particle examinations of rack areas and rod-box external
, surfaces revealed no indications, e No eddy-current, material comparator, or hardness tests were conducted.
e Dimensional checks of link pin locating dowels. all were satisfactory, e F,olts were torqued to standards, using a calibrated hydraulic wrench.
The items with unsatisfactory indications were dispositioned as follows:
e Galled threads, etc., were honed; galled washers were replaced with hardened components, e Linear indications on Train A rod-box external surfaces were deter-mined to be babbitt smears to the rod-thrust face areas from 'the adjacent journal bearings, and were deemed noncelevant, o Except for one that was replaced, bushings with score marks were deemed acceptable.
t e One link-pin was replaced due to galling found while replacing bushings.
TUGC0 did not check for connecting rod bowing because its inspection preceded the applicable OG report. Instead, TUGC0 relied on inspection for bearing and bushing wear patterns as evidence of rod distortion. The results were deemed acceptable. TUGC0 did not conduct nondestructive examination (NDE) inspections of the bolts an'd mating threads at the rod-box joint on Train 3, relying instead on acceptable results from the Train A inspections as su f ficient.
TUGC0 reports that no unfavorable indications were found on relevant areas of the wrist pin bushings on either engine as examined by liquid penetrant (Lp) methods.
I l As a conseyaince of their inspections and analyses, and the dispositions made on unsatisfactory components, TUGC0 believes tt t connecting rods of both engines now are fully adequate for their intended standby nuclear service.
f 3.16 9
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1 3.2.4.5 PNL Evaluations and Conclusions TDI and the Owners' Group each have conducted extensive investigations and analyses of the connecting rod failures. PNL has not been able to reach final closure on the sufficiency of their results, but generally concurs with their conclusions as to the failure mechanisms, subsequent corrective actions, and overall operability and reliabi'ity of the components if given sufficient surveillance and maintenance.
TUGC0 has appropriately addressed the generic issue of potential connect.
, ing rod problems through comprehensive disassembly and inspection (with certain exceptions) and appropriate analysis, replacement and refurbishment. pML remains concerned, however, about the following aspects:
e TUGCO's inspection by visual and LP examination of the rod-rack tooth surfaces did not reveal indications of concern. Yet PUL's representatives, in viewing these surfaces, saw numerous surface abnormalities--long, linear striations--on many teeth, often with matching indications on the mating surfaces. These indications were not considered to seriously affect the engine operability or reliability. PNL's consultants believed these evidenced the start of fretting that might result from inadequate bolt and joint preload.
e TUGC0 did not lap the mating surfaces or check contact by " blueing" techniques in the reassembly of the engines. (" Blueing" is a process confirming mating surface contact area by using a thin surface coating of a chemical that, when pressed or rubbed against a mating surface, will indicate where contact is achieved.)
e PNL does not agree with TUGCO's contention that bearing and bushing wear patterns will, of themselves, establish clear proof of rod straightness. If indeed such bowing were to occur in forging, the I
i process of boring for wrist, link and crank pins should provide end-connection alignment. Then only rod fl.exure, over a prolonged period, would show up in noticeable bearing wear patterns. Mean-while, potential fatigue stresses would accumulate. However, this 3.17 l
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area remains one of concern subject to findings of the OG strain-gauge testing on connecting rods.
e PNL representatives observed burrs and sharp edges at bolt hole ,
openings in various rods at the master-slave- joint, which represent potential stress risers.
Since publication of George (August 15,1984), TUGC0 has reported the following: 1) burrs and sharp edges were removed on bolt holes 'of Train B rods before reassembly; 2) the rod racks were " blued-in" at the T0! factory before original engine assembly; 3) upon being advised of PNL observers' concerns on the apparent fretting, TUGC0 had those surfaces inspected by TOI personnel; TUGC0 was informed the observed amount was typical of vee engines (even with so
~
few hours of operation), but was encouraged to hone or stone a'ny " raised" areas and then reassemble, which was done on Train 8. PNL understands this informa-tion will be confirmed in writing to NRC. PNL believes this confirming docu-ment will alle~viate concerns with respect to rod-rack tooth fretting and the potential for stress risers at bolt hole openings.
PNL concludes from all available and confirmatory information that the connecting rods on the Comanche Peak engines--both Train A and Train B--can safely and reliably perform their intended function through the first refueling cycle. This is stated with the following rationale and provisos:
e The CPSES engine connecting rod boxes have 1 1/2-inch bolts (rather than 17/8-inch bolts); this provides a rod-box structure with a higher factor of safety in the area of concern.
e The CPSES engines have very few service hours logged relative to service of engines when rod-box failures occurred (many thousands of hours).
- e Engine operations will be limited to loads no higher than 185 psig
! BMEP. This will limit firing load effects on rack surfaces and bolting, and on any rod bowing.
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e TUGC0 conducts an adequate reinspection of the rod-box bolt tension at acceptable time intervals; and examines the condition of bolt. hole entrances and teeth, and rod straightness, at the first refueling outage.
3.2.5 Connecting Rod Bearing Shells Part No. 02-3408 -
Owners' Group Report FaAA-84-31 3.2.5.1 Component Fu'nction The connecting rod bearings interface the connecting rods with the crank-shaft. They are of cast aluminum alloy with a thin babbitt overlay, and are furnished in two identical halves. They are lubricated undEr pressure, and a substantial flow of oil proceeds through machined channels in the shells from the drilled crait. shaft oil holes to the passageways within the connecting rods and on to the pistons and intervening bearing surfaces. The upper bearing half is subject to the piston firing loads and therefore is more critical.
Failure can occur through inadequate oil flow or pressure, excessive or unplanned loadings, structural anomalies (from design or manufacture), or through erosion of the babbitt layer in crucial areas. Bearings are also subject to particle or chemical contamination in the oil, including water, or even the wrong oil selection for the duty, any of which can lead to failure.
The f ailure mechanism generally is gradual, and its anset can be detected by prudent surveillance of oil and filter conditions. However, a substantial structural problem, excessive cylinder loads, or heavy water contamination can lead to rapid failure. This can affect the shaft, sometimes with irreparable results.
. In light of the several conditions affecting bearings, the need for replacement is not uncommon. However, in customary service, bearing life gen.
~
erally is measured in multiples of 10 4hours, given reasonable service conditions. '
I l \ 3.19 l
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3.2.5.2 Component Problem History No significant failures of the TDI OSRV-type diesel engine connecting rod bearing shells have been reported in nuclear applications. However, some have been replaced _because of deterioration due to inservice conditions or because they were found to be in nonconformance with Owners' Group recommendations regarding voids in the base material.
l 3.2.5.3 Owners' Group Status Various problems were er. countered in the inline TDI OSR engines at Shoreham. Edge cracking occurred, allegedly due to inappropriate bearing shell overhang beyond the support structure. In checking the cause, the OG also concluded that bearing serv'iceability was influenced by the number and size of subsurface voids in the aluminum castings, and subsequently established criteria for their detection and evaluation.
The OG has investigated both the Shoreham (inline) and Grand Gulf (vee) bearing shells. On their behalf, Failure Analysis Associates conducted various analyses. They concluded that the bearings are suitable for the intended service, provided 1) they conform to the manufacturer's specification and
- 2) they meet the criterion for subsurface voids developed by FaAA for the -
Owners' Group. Indeed, on the basis of their analyses of the Shoreham bearing conditions (reflecting their brief service operating hours and loads, etc.),
FaAA concluded that the different, but generally similar, bearings in the vee -
engines can expect a 38,000-hour life at full load, if void criteria are met.
3.2.5.4 TUGC0 Status Both Train A and 8 EDGs were insp+-ted by the following means:
e full dimensional measurement e visual inspection for scoring, galling, cracks or excessive wear t e liquid penetrant inspection for linear indications l
e radiographic inspection for internal defects.
On Train A, eddy-current testing was done on those linear indications requiring further evaluation.
3.20 t
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In summary, the results for Train A were:
e All showed some visible markings; they were' deemed reusable, except as noted below. (Wear was not referenced.)
e All showed some linear indications via LP test.
e Following radiographic and/or eddy current inspection, one upper and four lower shells were rejected, and one upper shell was relegated to only lower service. All others were deemed reusable.
For Train B, TUGC0 found:
e Ten shells had markings; they were deemed reusable except as noted below. (Wear was not referenced.)
e Four showed linear indications via LP test.
e Following radiographic inspection, three upper and one lower shells were rejected, which included three that had detectable visual or LP indications. All others were deemed reusable.
TUGC0 cone.ludes that, with the evaluations and replacements made, tne con-necting rod bearing shells in the reassembled engines are " adequate for service through the first cycle of operation."-
3.2.5.5 PNL Evaluation and Conclusions PNL representatives viewed bearing shells during the period of inspection of Train 8, and noted numerous surface blemishes. No meaningful cavitation or erosion was seen. PNL also has reviewed both TUGC0 and OG reports and certain documentation. The OG/FaAA conclusion extrapolating the brief Shoreham experience to 38,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />' expectable life on the larger-diameter vee bearings nas not been accepted by P'NL and its consultants.
- PNL does conclude that, on the basis of engine loading limitations and
, monitoring of oil pressure and condition, the connecting rod bearings for both Train A and Train B will be adequate to operate reliably through the first refueling outage.
3.21 ~
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3.2.6 Piston Skirts Part No. 02-341A Owners' Group Reports FaAA-84-2-14 and FaAA-84-5-18 3.2.6.1 Component Function The piston (as an assembly of piston crown and piston skirt, along with rings, piston pin, et al.) receives the thrust of combustion in the cylinder and transfers it to the connecting rod. The. cast steel crown carries the
~
immediate pressure load and thermal conditions; the skirt, of ductile iron, actually transfers the load to the piston pin / connecting rod and guides the reciprocating motion within the cylinder.~ Such a two-piece piston structure is relatively common to large, modern, high-output engines.
In general, failure is most apt to reflect excessive pressure and thermal stresses, of Doth high-cycle and low-cycle character. Durabilicy is affected by material selection and fabrication quality, as well as design characteris-tics. A crown separation will require immediate shutdown; it is likely to lead quickly to serious cylinder, head, and rod damage and piston seizure, with adverse impact on the crankshaft and possible crankcase explosion. Hence, adequate attachment of crown to skirt is a serious concern.
3.2.6.2 Component Problem History .
l l
TDI has utilized several skirt designs in R-4 engines, variously desig-nated models AF, AH, AN, and AE. Most early nuclear service engines were furnished with AF and AH skirts, although one plant received AN skirts. The EDGs at CPSES were outfitted with AH skirts, which are reportedly-quite similar to AF skirts.
Cracks have bean found in a number of AF skirts, including earlier configurations of the TDI engines at Grand Gulf and Shoreham. The area of sensitivity was at a " boss" whe.'e the bolts join the crown and skirt together. Some skirts also have had problems at the interface of an internal, circumferential rib and the piston-pin boss. A redesign of the stud / boss area-and attachment sys".em (washers) constitutes the principal change from an AF to an AE model. No operational failures have been reported to date on the rede-signed piston skirt in either nuclear or non-nuclear installations. Kodiak (a 3.22 -
I baseload electrical generation station) has operated in excess of 6000 hours0.0694 days <br />1.667 hours <br />0.00992 weeks <br />0.00228 months <br /> at approximately 185 psig 'BMEP (1200 psig maximum firing pressure) with AE skirts in a V-16 engine. A TDI R-5 test engine was operated in excess of 600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br />, with a maximum firing pressure of 2000 psig and BMEP of 275 psig, with a i slightly modified AE skirt design; without known cracks. l 3.2.6.3 Owners' Group Status Piston skirts have been identified by the TOI Owners' Group as one of the generic problem components. The Owners' Group consultant, Failure Analysis Associates (FaAA), analyzed the AE piston skirt design and concluded that tne
- AE skirts still may crack at 10% overload of nameplate rating (i.e., 248 BMEP),
but that cracks will not propagate to the point of actual functional failure.
Cracks have been analyzed to occur in the vicinity of the structural rib and bolting boss inside the skirt. The failure will occur primarily as a function of hign-cycle fatigue (i.e., a large number of stress cycles, reflective of the piston's duty in absorbing and transmitting the power thrust). Il materials of tnis nature can survive, under load, for 107 cycles, then they are generally 7
capable of much longer (than 10 cycle) lives at that load. In four-cycle engines like these, operating at 450 rpm, 10 cycles will occur in 741 hours0.00858 days <br />0.206 hours <br />0.00123 weeks <br />2.819505e-4 months <br />.
7 The issue of AE piston skirts was addressed by PNL in Section 4.0 of Review and ' Evaluation of TDI Diesel Generator Owners' Group Program Plan ,
PNL-5161 (June 1984), relative to nuclear plants seeking interim licensing ,
(prior to finalization and full implementation of .the OGPP). PNL concluded that plants with AE piston skirts expecting sustained emergency load require-ments not exceeding 185 psig BMEP could logically and safely be licensed, because AE piston skirt testing to 107 cycles (740 hours0.00856 days <br />0.206 hours <br />0.00122 weeks <br />2.8157e-4 months <br />) at or above this load has been confirmed.
- 3.2.6.4 TUGC0 Status
. None of the original AH skirts failed in their brief history at CPSES.
Nevertheless, TUGC0 elected to replace them with. AE piston skirts. The AH skirts were not inspected upon removal (but reportedly some or all w4'l be inspected at TOI). The new, replacement AE skirts were inspected, including LP examination in skirt boss areas. Three showed linear indications. Two of 3.23
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these were eddy-current tested to determine depth of cracks; the depth of the l
third visibly extended through a " lip" of metal (the region that develops as a result of machining the washer landing into the skirt). All were determined by TUGC0 (with advice of TDI and the OG) to be in supposedly noncritical areas of the skirt structure, so all were ground out to sound metal and satisfactorily l- LP-tested again. All were reinstalle'd.
Wrist pins of both engines were examined. Of the 32 total, six were found to have rejectable scoring, galling, pitting, chipping, or heat-checking. In a telephone conversation among TUGCO, NRC, and PNL, TUGC0 reported that none was found to have linear indications. All were replaced. A sampling of wrist pins also was checked dimensionally and for materials and hardness, with satisfactory results.
The new skirts have no operational history at CPSES. However, predicated
~
on tne 0G/FaAA analyses, the generally favorable history in service elsewhere, and the imposed operating limit of 185 psig BMEP, TUGC0 concludes the skirts now in the engines will be adequate for service througn the first operating cycle.
3.2.6.5 PNL Evaluation and Conclusions -
PNL has reviewed the two applicable OG/FaAA generic reports on pisten skirts and notes the successful operation reported for the TOI R-5 test engine equipped with AE piston skirts. On these bases, PNL concludes that the AE piston skirts can be expected to operate reliably through the first refueling cycle under conditions no higher than 185 psig BMEP. PNL notes that three new skirts were received from TCI with indications. These indications were ground out by TUGC0 and satisfactorily reexamined to OG specifications. PNL concurs with TUGC0 that, following successful preoperational testing, these skirts--of both Train A and Train B--can be expected to operate reliably at least,througn the first operating cycle.
3.2.7 Cylinder Liners Part No. 02-315C Owners' Group Report FaAA-84-5 4 l
3.24 l.
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- 1 3.2.7.1 ' Component Function Engines of this size and character are designed with individual, removable cylinder liners, which fit inside the cylinder block. The liners contain the pistons and are capped at the upper end by the cylinder head. Thus, they act as containment for the firing forces, subject to the stress and heat thereof, and the reciprocating travel of the pistons. Their outer surfaces are cooled by jacket water circulating within the block. The lower end is sealed against an opening in the block floor with 0-rings. The upper end has an external, circumferential ledge, which seats on the block's " liner landing." The head is gasketed and bolted in compression against the upper liner annulus, to seal in the high-pressure combustion gases. The liner is of nodular iron, selected for
-its strength, castability, and durability against the scraping action of the pistons and rings.
Liners generally do not fail, but they can be adversely affected by inade-quate or inappropriate lubrication, the forces and heat of the combustion processes, the character of the pistons and rings, and the quality of fuels.
Failure most often is in the form of scoring by broken rings or carbon deposits, or " scuffing" by the action of the piston on the cylinder walls, due to one or more of the factors mentioned. If such conditions are severe enough, a piston will seize and cause significant damage to liner, head, and connecting rod, and even to the crankshaft. A crankcase explosion can result.
3.2.7.2 Comoonent Problem History Only one . incident of cylinder liner " failure" in nuclear service is known. This failure occurred in 1982 at Grand Gulf when a piston crown sepa-rated from the skirt during testing of the Division II engine and marred the liner.
- 3.2.7.3 Owners' Group Status The OG included considerations of liners in their study of cylinder blocks. Two concerns were uncovered:
e *he TOI design calls for the liner to protrude slightly above the top deck of the block, to ensure a tight, compressive fit against the head and gasket. However, this produces bending moments in the head l l
3.25 l
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E and substantial shear stresses on the cast iron liner landing of the block. Both aspects are suspect in some of the real or incipient failures in those components. TDI has approved remachining to reduce the protrusion.
e The design also calls for a tight fit between the outer ring of the liner ledge and the matching counterbore of the block. There is some concern by the Owners' Group that this could increase hoop stresses in the block, which might lead to block cracks.
3.2.7.4 TUGC0 Status In its inspection process, TUGC0 verified that all cylinder dimensions were satisfactory. All liners also were inspected for signs of interior wear,.
scoring, or scuffing (although each engine had operated only 92 hours0.00106 days <br />0.0256 hours <br />1.521164e-4 weeks <br />3.5006e-5 months <br />), and for marring at the liner / block interface.
One liner from Train A was replaced due to a casting flaw. Two liners on f Train B were replaced due to-undefined exterior surface indications. All others were deemed reusable as was, or with insignificant indications and spurious metallic surface coatings. All were honed to ensure that the new skirts and rings would seat properly.
TUGC0 also machined all upper ledges so that the protrusion of the liner tops would be within TOI's revised standards.
One of the rejected liners is at FaAA for destructive examination; results
- will be reported in the CPSES Phase 2 report.
TUGC0 concludes that the liners in these two EDGs at CPSES are adequate for nuclear standby service.
l 3.2.7.5 PNL Evaluation and Conclusions PNL representatives viewed the liners removed from Train B, finding no surface indications of significance. In PNL's view , TUGC0 has appropriately inspected the liners and taken proper action regarding findings. Regarding the possibility o hoop stress induced cracks, PNL notes that 1) there were no relevant findings at Comanche . Peak, 2) TUGC0 has agreed to frequent inspections for critical block cracks (see Section 3.2.2.4), and 3) TUGC0 plans to imple-3.26 G
[ .
ment any Owners' Group reconnendations in this regard.. PNL therefore concludes the liners are suitable for nuclear service pending receipt of confirmatory information regarding satisfactory results of the destructive examination' of the liner sent to FaAA.
3.2.8 Cylinder Heads Part No. 02-360A Owners' Group Report FaAA-84-15-12 3.2.8.1 Comoonent Function The cylinder head caps the cylinder, providing (along with the liners) the enclosure needed to direct the combustion forces against the piston. Its lowest surface, facing tne cylinder, is known as the firedeck. In the TOI design there are two intake and two exhaust valves in the flat surface of tne firedeck, plus the fuel injector and an air starting valve. All these openings and their associated passageways have to be cast into the structure of the head, which, in itself, must also contain substantial internal jacket water (JW) passages for cooling. In addition to the firedeck there is a top deck or enclosure and an intermediate deck providing structural rigidity and control over JW flow. )
The head is bolted to the cylinder block via a number of studs extending througn the head from the block. On top of the cylinder head are two more com-ponents: the subcover or rocker box, which supports the valve actuating mecha-nisms, and a light top cover.
The TDI R 4 heads are cast of steel alloy. Casting a heac of tnis com-plexity is difficult, particularly in steel. The internal passages are achieved via casting cores, which are challenging to hold in place during casting. Consequently, such heads have had a tendency to have uneven and/or incomplete sections. These can lead to a variety of flaws or indications, some of which can be repaired in the manufacturing and machining process.
Failures have tended to be mostly rather superficial linear indications with no consequential results. However, some deficiencies lead to warpages or cracks. The latter, if through to the JW passages, will result in leaks of water into the cylinder when the engine is down, and of combustion gases into
~
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the JW during operation. The former can result in a " block" of water in the cylinder, which could severely damage head, piston, rod bearings, and shaft on startup.
3.2.8.2 Component Problem History Numerous reports on TDI cast steel cylinder head failures are available from both the nuclear and non-nuclear industry. For identification purposes, TDI cylinder heads have been classified by FaAA as I, II and III, all under the same part nunber. Group I heads include those cast prior to October 1978; Group II heads are those cast between October 1978 and September 1980; and Group III comprises heads cast after September 1980. The distinctions involve both design changes to facilitate casting control and general quality control improvements. Most instances of cracked heads have involved Group I. Only five instances of water leaks in Group II and III heads have been reported, all in marine applications. Most of the reported cracks initiated at the stellited valve seats.
j The most recent known head failure was reported by Mississippi power &.
Lignt relevant to their Division I TDI diesel engine at Grand Gulf (letter to NRC dated July 30, 1984, AECM 84/0401). It reported a 2-inch through-wall crack in the right exhaust port casting surface between the valve seat area and the exhaust valve guide. This allowed jacket water to penetrate from the head cooling passages into the cylinder cavity, and was detected 3y barring-over the l engine with cylinder cocks open. The specific head group classification of this head was not reported. However, the affected head was supplied witn the engine and had undergone 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> of operation. Of this total, approximately 335 operating hours were at 100% load (7000 kW, 225 psig BMEp) and 31 hours3.587963e-4 days <br />0.00861 hours <br />5.125661e-5 weeks <br />1.17955e-5 months <br /> were at 110% load. This failure is still undergoing investigation; however, l because MP&L knows of no occurrence of other similar failure, it concludes this was a unique, isolated event.
3.2.8.3 Owners' Grouc Status The cylinder heads are included in the TDI Owners' Group generic proble..
category. Failure Analysis Associates' mechanical and thermal stress calcu-lations, which did not include finite element calculations, concluded that l Group I, II, and III heads, as designed, are adequate for the service intended.
3.28
The report recommends that Group I. and II. heads be 100% inspected by liquid penetrant, magnetic particle, and ultrasonic testing to determine firedeck thickness. For Group III heads, sample inspection as described above is recom-mended. For all three groups of heads, FaAA recommended rolling the engine over.before manual startup, with cylinder cocks open,'to assure no water has leaked into the cylinders.
3.2.8.4 TUGC0 Status In response to concern over heads of Group I and II -as originally fur-
, nished on the CPSES engines--TUGC0 replaced all 32 heads on Unit 1 Trains A and B, with Group III heads. All .new heads were. inspected visually and by mag-netic particle, liquid penetrant, and ultrasonic techniques. All were disposi-
^
i tioned as acceptable by TUGCO.
Predicated on 1) improved manufacturing practices at TDI reflected in :ne Group III heads, 2) TUGCO's satisfactory results in inspecting them, and 3) the favorable conclusions claimed in the OG review of the latest head grouping, TUGC0 concludes that the new heads now installed in Trains A and B are adequate for standby nuclear service.
3.2.8.5 PNL Evaluation and Conclusions .
In general, pML concurs that, with the following provisos, the Group III TDI R 4 heads should serve satisfactorily for both Train A and Train 3 engines enrough the first refueling cycle:
e Engines should be air-rolled over with cylinder cocks open 4 to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, and again at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, after any operation, and thereafter prior to any planned start, to detect any water leakage into the cylinders.
- e. The engines should be limited to loads of 185 psig BMEP or less (as
! already committed to by TUGCO)'.
3.2.9 Cylin' der Head Studs Part No. 02-315E -
Owners' Group Report Emergency Diesel Generator Cylinder Head Stud Stress l Analysis (SWEco March 1984) 3.29
3.2.9.1 Comoonent Function Eight studs per cylinder are used to bolt the heads to the cylinder block. Together they transmit the power 1oad from the head to the block.
Head bolts are not normally found to stretch or break; however, these occurrences are possible, due to faulty design, materials or fabrication, or excessive firing pressure. Fatigue failure is a greater concern, given reasonable operating conditions. This will occur if preload is insufficient and the bolts go through many cycles of loading. Once a bolt yields or breaks, its neighbors must carry increased burden, and the head is unevenly stressed.
This generally results in escaping combustion gases, with the attending hazards of heat and fire, as well as physical and metallurgical damage to head and block.
3.2.9.2 Component Problem History TDI has employed two basic stud designs recently. One is of straight snank diameter. There has been concern that its tight fit within the block stud opening, coupled with inadequate preload, could put side thrusts on the block and contribute to block fractures. A second design uses a necked-down shank. This design not only avoids any possible stud-to-bore contact, but also reduces the preload needed to maintain positive stresses during the firing cycle.
To date, no failure of cylinder head studs has been reported in the nuclear industry. However, some isolated failures have been reported in the non-nuclear field. The cause has not been established.
3.2.9.3 Owners' Group Status Stone a Webster Engineering Corporation (SWEco) has analyzed both the old design studs and new necked-down studs developed by TDI to minimize potential cylinder block cracking, and has concluded that both stud designs are adequate for the service intended, provided proper stud preload is applied.
3.2.9.4 TUGC0 Star"s ,,
I The CPSES engines were furnished originally with the straight-shank stud design. In light of evolving concern over these, TUGC0 decided to replace all 3.30
t (128 per engine) with 256 studs of the newest design; replacement was done in the recent reassembly.
Of the original studs, 32 were given material tests (with satisfactory conclusions). The new studs have documented material properties, so were not rechecked by TUGCO.
Of the original 256 studs, four were given careful visual inspection.
Galling (at the bottom washer interface) and other marks were evidenced on all. Additionally, three showed areas of heavy rusting; no further comment has been made on causes, but TUGC0 has recently advised NRC that rusting was preva-lent on many studs. They characterized the rust as typical of atmospheric-induced rust during storage.
TUGC0 concludes, from the OG/SWEco evaluation, that these replacement studs are satisfactory for their intended service.
3.2.9.5 PNL Evaluation and Conclusions PNL finds that TUGCO's actions to replace all studs with tho'se of the necked-down design and documented material properties are acceptable. PNL believes TUGCO's explanations of the bolt rust is reasonable.
PNL has learned that TUGC00 has confirmed to NRC that these bolts were installed with proper preloading. PNL therefore concludes that the studs now installed will be reliable for normal nuclear standby service, for Train A and Train B.
3.2.10 Push Rods Part No. 02-390C & 0 Owners' Group Report FaAA-84-3-17 3.2.10.1 Component Function Push rods transmit the cam action from the camshaft on the engine side to the intake and exhaust valves in the head. One main rod extends from the camshaft to the subcover where it acts directly on the intake valve rocker arms.
The second main rod transfers cam action to an intermediate rocker in the subcover and on through an intermediate push rod to the exhaust valve rocker arms. They are subject to high-acceleration compressive forces as they 3.31 l
- I 4
respond to the cams. Fundamentally, these are steel tubes with rounded ends, to fit the various mating sockets.
A failure would, at the least, reduce valve action and, thus, cylinder performance. Total inoperability of a cylinder could result, but would not necessarily lead to immediate engine shutdown. Because these components are always in compression, failure modes are limited, assuming reasonably good design.
3.2.10.2 Component Problem History TDI push rods originally had tubular steel bodies fitted with forged and hardened steel end pieces, attached by plug welds. An estimated 2?. reportedly developed cracks in or around the plug welds. A " ball-end" push rod design introduced later consisted of a tubular steel body with a high-carbon steel ball fillet-welded to each end. This design proved to be prone to cracking at the weld. A third design, consisting of a tubular steel body friction-welded on each end to a forged plug having a machined, hemispherical shape, was Onen introduced. This third configuration is referred to as the friction-welded design.
3.2.10.3 Owners' Grouo Status Because industry (both nuclear and non-nuclear) had expressed substantial concern about the continued integrity of TOI push rods, the TOI Owners' Group included the component in the known generic problem category for specific study and resolution. Failure Analysis Associates has performed stress analyses as well as stress tests to 107 cycles on a sample of the friction-welded push rods, at conditions simulating full engine nameplate loading. No sign of abnormal wear or deterioration of the welded joints or ends'was observed.
Other nuclear owners have run these versions in actual service, witn no adverse results, beyond 107 cycles.
FaAA, in their analyses, concludes this design is serviceable as required, but does provide stipulations for inspection and action, including destructive examination of a random sample from each plant.
3.32 '
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l 3.2.10.4 TUGC0 Status Following 92 hours0.00106 days <br />0.0256 hours <br />1.521164e-4 weeks <br />3.5006e-5 months <br /> of operation, TUGC0 inspected four of its original push rods of the ball-end type. Three had rejectable indications in ene fillet welds, though none had actually failed. TUGC0 decided to replace all push rods, an action.which, in conjunction with a decision to also substitute AE for AH piston skirts, triggered the whole process of engine inspection at CPSES a't this early date.
All ball-end push rods were replaced with friction-welded rods.
Satisfactory LP tests were run on the welds. However, TUGC0 has appealed to the 10 G its requirement for destructive testing of a sample rod, believing that the tests run, coupled with the OG generic report conclusions, obviate the need. In a telephone discussion among TUGCO,, NRC, and PNL, TUGC0 reported that the OG has informed them that destructive tests are not currentl'y needed. They recommend instead that a random check be made of new purchases, to confirm manufacturing quality.
TUGC0 concludes that the new rods, as installed, are reliably serviceable for their standby nuclear service.
4 3.2.10.5 PNL Evaluation and Conclusions After reviewing the FaAA report, the TUGC0 actions and reports, and examining push rods in extended service elsewhere, PNL concludes that such rods of the friction-welded design are satisfactory for their intended purpose in both Train A and Train B. Based on successful operating history, PNL' concurs with the revised Owners' Group recommendations regarding destructive testing.
3.2.11 Rocker Arm Caoscrews Part No. 02-390G
! Owners' Group Reports Emergency Diesel Generator Rocker Arm Caoscrew Stress Analysis (SWEco March 1984, July 1984) 3.2.11.1 Component Function The rocker ann capscrews bolt in place the rocker arm shaft bearing caps in the subcover assemblies. They are fairly standard bolting materials. A l
failure would weaken or cancel the restraints on a rocker shaft and cause malfunction of intake or exhaust valves. Reduced engine output would result.
3.33
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i
3.2.11.2 Component Problem History Rocker arm capscrew failures at Shoreham have been reported. There have been no reports of similar failures elsewhere.
3.2.11.3 Owners' Group Status Stone s Webster Engineering Corporation, a consultant to the Owners' Group, has performed stress analyses of both the original capscrew design with a straight shank (the type that failed at Shoreham) and a newer design incorpo-rating a necked-down shank. SWEco has concluded that both designs are adequate for the service intended. They have attributed the failure at Shoreham to insufficient preload.
3.2.11.4 TUGC0 Status The capscrews at CPSES are of the necked-down model.
Pursuant to OG/SWECo analyses and recommendations, TUGC0 examined the capscrews from the disassembled heads by magnetic particle inspection, with favorable results.
However, no material verification was performed, as had been recommended; TUGC0 now proposes to do this before fuel loading, while crankshaft oil holes are being inspected. .
The capscrews were reinstalled at recommended torques. TUGC0 concludes--
subject to favorable material verification--that they are properly serviceable for their intended function at CPSES.
3.2.11.5 PNL Evaluation and Conclusions PNL concludes, from the OG analyses and the inspection results at CPSES, and from ooservation of high-cycle operating results on identical components elsewhere, that TUGCO's conclusion is acceptable. PNL concurs that the capscr-ews are serviceable as intended, subject to the TUGC0 planned material confirmation prior to fuel loading. -
3.2.12 Turbochargers Part No. MP022/3 <-
Owners' Group Report FaAA-84-5-7 i
3.34 i
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i i
3.2.12.1 Component Function - q The turbochargers (two per engine) provide pressurized air to the cylinders for combustion of more fuel than would be possible with a "normally aspirated" engine. The turbochargers consist principally of a turbine, driven by engine exhaust gases, directly driving an air compressor wheel. The -
associated housing ducts the air and exhaust to and from the two rotors, and holds the inlet vanes of the turbine, which direct the exhaust gases toward the '
turbine wheel blades. Turbine speed changes with engine load (i.e., gas volume, pressure and temperature), with maximum speed--depending on specific turbine selection and design parameters--over 10,000 rpm.
Because close tolerances and high rotating speeds are necessary for effi-4 ciency, and because of temperature levels approaching 1200*F at the exhaust inlet, all components are sensitive to temperature, pressure, structural loads, and contaminants or particles in the gas and air streams. The radial and thrust bearings require particalar care.
i Vanes and blades are sor.etimes lost due to heat and vibration, or fractured by impact of particles, such as fractured vanes or valves. Undue stresses from connected exhaust piping or inappropriate supports cause rotor wear at stator interface. Inadequate bearing lubrication (and the cooling the oil provides) leads to bearing' failure. Depending on the severity of the situation, shutdown can come quickly, t.ut usually is not immediate.
/
The turbochargers on the CPSES TDI OSR V-16 engines are model 90G units manuf actured by the E111o*t Company. -
3.2.12.2 Comoonent Problem History various problems have occurred in the turbochargers on TOI OSR 4 engines in nuclear service. The principal one has been the rapid deterioration of the combination turbine thrust / radial bearings. There also have been concerns over missing exhaust inlet vanes, missing or broken bolts joining the exhaust mani-fold to the turbocharger at the inlet, and broken bolts and welds in support mounts. To date, thrust . bearing problems hs.e evidenced themselves at the Comanche Peak, Shoreham, Catawba, and San Onofre nuclear plants.
3.35
-- - . - ., , , _ - _ _ _ - - , . - _ _ y - ~ _ -m - . - - - ,
e 1,
Because nuclear EDGs havelunusual quick-start requirements--and are tested extensively to assure reliability, for such duty--the owners and TOI investi-L gated the failure parameters earfy in the history of such service. It was recognized that the bea' ring"and bearing lubrication systems inherent in the 90G design did not provide adequate lubrication on the bearing thrust pads and rotor thrust collars under fast startup conditions to high loads. TDI insti-tuted two steps of modification 3 Jn anjattempt[to address this problem; one instituted and, modified the oil drip system and the second provided for manual prelubrication prior to planned starts. , .
3.2.12.3 Owners' Group Status In behalf of the Owners' Group, FaAA undertook an extensive study of causes of reported failures in' nuclear ser'vice. Jhe net result was an affirma-tion of inadaquate startup lubrication. Briefly, the resulting recommendations were:
- Retain and use a " drip system" that directs a small flow of oil toward the bearings 'at all times in standby, but increases the flow of oil to 0.35 gph. (Higher flows are apt to flood past the bearing into the exhaust manifolds and crea:e fire risk.) .
l e Provide and use.an auxiliary prelubrication pumo to direct substan-
- tial flow to the bearings immadiately prior to planned startups, e Maintain oil filtration at 10 microns or better and utilize spectro-chemical and ferrographic oil analysis regularly, e Enhance bearing inspection programs. At least one bearing should be inspected at a station following every 100 starts, of whatever nature. Inspecti_on should also be done following 40 starts without manual prelube.
An OG supplementary report dealing with turbocharger vanes and inlet capscrews has yet to be released. -
G P
h 3.36 t
r.. - - - -, , _ , - - . . v. -- -, _ _ _ _ _ - _ _ _ . - - _
3.2.12.4 TUGC0 Status TUGC0 instituted the drip system on the Unit 1 EDGs in 1980, prior to EDG .,
operation.- When the engines were disassembled early in 1984, all four turbochargers were thoroughly inspected.
Train A inspections, conducted after 67. local starts and 92 hours0.00106 days <br />0.0256 hours <br />1.521164e-4 weeks <br />3.5006e-5 months <br /> total operation, revealed that:
, e Bearings were scratched, scored, pitted, and had lost babbitt. They were replaced.
. e Several turbine blades, fan blades, and nozzle vanes were nicked, pitted, or bent. Shafts, thrust collars, and oil seals were unsatisfactory. Rotors were replaced, but stator components were deemed acceptable and returned to service.
Results for Train 8, inspected after 83 local starts and 92 hours0.00106 days <br />0.0256 hours <br />1.521164e-4 weeks <br />3.5006e-5 months <br /> total operation, were:
e Bearings were worn, scratched, and scored. On one bank they were replaced; on the other, the entire turbocharger was replaced.
e Turbine and fan blades and. nozzle vanes were variously nicked and gouged. One vane was missing from the right bank nozzle ring. Welds in the centerplug of both were broken. The right bank turbocharger assemoly was totally replaced; appropriate replacements and repairs were made on the left bank unit.
In addition to these maintenance efforts, TUGC0 has committed to the basics of the OG plan for turbocharger modifications, operations and main-tenance, including inspection of the turbocharger thrust bearings of any engine experiencing 40 'ast starts (starts without manual prelubrication of the beatings).
After making the cited changes, and in light of the OG/FaAA analyses tnat claim satisfactory 0/R if their recommendations .are followed (which TUGCO.has agreed to), TUGC0 concludes these turbochargers now installed will adequately perform their intended function through the first operating cycle, unless they experience an abnormally high number of starts. (TUGCO's August 15, 1984, 3.37
submittal provides information that Train A has had another 45 starts, Train 8 another 54, since these maintenan'ce activities, as of mid-August 1984 TUGC0 has informed PNL a.nd NRC that all'of these utilized manual prelube prior to the start.)
3.2.12.5 PNL Evaluation and Conclusions PNL h.as reviewed the FaAA report referenced above, the results of the June 22, 1984, meeting among representatives of FaAA, the Owners' Group, NRC, and PNL, and the inspection data presented by TUGCO. During the Comanche Peak site visit on May 24 and 25, 1984, PNL examined the Train B engine turbocharger-bearings, which were scored and substantially worn. PNL also has examined the prelube system at other, similar plants. On these bases, PNL concludes that a similar new prelube system now installed on the diessls at CPSES will provide sufficient additional lubrication to augment the protection of the turbocharger bearings during planned fast starts. Further, in PNL's view, the few unplanned fast starts that may occur without prelube will not lead to bearing failure prior to the first refueling outage. PNL notes .that TUGC0 has agreed to modify the drip lubrication system in accordance with the latest TDI recomendations.
PNL also not.es that TUGC0 has established a planned program of relevant'sur-veillance and maintenance and, at the first refueling outage, has agreed to implement the OG recomendations for inspections. It is expecte.d that TUGC0 i
will also appropriately comply with OG recommendations regarding capscrews, vanes, and mounting and supports that may result from the Phase ? DR/QR.
On the bases of the above,;PNL concludes that the turbochargers at CPSES Unit 1--Trair. A and Triin B--are adequately operable and reliable until the first refueling outage.
3.2.13 Jacket Water Pumo ->
Part No. 02-425A 4 .
Owners' Group Report Emerge.1cy Diesel Generator Engine Driven Jacket Water Pumo Design Review (.euECo April 1984) 3.2.13.1 Component Function The engine driven jacket water pump furnishes water to the engine jackets (i.e., the cylinder block surrounding the liners) and thence to the heads.
3.38 S
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Water is also sent to the turbocharger jackets. They are customary centrifugal pumps, driven by a power takeoff from the front-end gear case.
Without the ' pumps (or an energency backup), the engine will quickly shut down due to excessive temperatures. Such pumps generally are trouble-free, but occasionally develop problems of shaft seals, bearings, and drive mechanisms.
3.2.13.2 Component Problem History A TDI engine at Shoreham has experienced a jacket water pump shaft failure. There is no history of failure's on jacket water pumps' designed for
. the V-16 engines.
3.2.13.3 Owners' Grouc Status Stone & Webster has investigated the jacket water pumps as installed on the TDI in-line and vee engines. They reviewed these jacket water pumps from the standpoints of mechanical design, material suitability, and hydraulic performence. Stone & Webster found the pumps such as those installed on the Comanche Peak Train A and B engines to be acceptable, with a recommendation
't hat a limiting torque be established for the pump shaft nut holding the
" external spline" in the shaft taper.
3.2.13.4 TUGC0 Status Ouring inspection, both Tratn A and B pumps were examined. Material com-parator and hardness tests on Train A were satisfactory. Excessive wear was noted on the Train A wear ring, which exhibited galling, and the impeller was loose on the shaft. The Train B ' impeller back plate was found deformed (pos-sibly due to disassembly efforts). The Train A pump was replaced totally; the Train B pump impeller was replaced.
TUGC0 concludes that, with these steps taken and the spline nuts properly torqued, the pumps are now ready for their intended service. ,
3.2.13.5 PNL Evaluation and Conclusions PNL concurs with TUGC0 and concludes that these pumps--for Train A and Train 8--are serviceable for their intended use in the Comanche Peak EDGs.
4
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i 3.2.14 High-Pressure Fuel 011 Tubing Part No. 02-365C Owners' Group Report Emergency Diesel Generator Fuel Oil Injection Tubing (SWEco April 1984) 3.2.14.1 Component Function The high-pressure fuel oil tubing carries the fuel oil from the cam-driven injection pumps on the engine sides to the injector nozzles in the heads. This oil is under pulsating and quite high pressure (-400 psi to 15,000 psi once each cycle); hence, any flaws in the steel tubing or fittings used, or any breaks caused by vibration, etc., will release oil in high-pressure bursts, with consequential fire risks.
3.2.14.2 Comoonent Problem History High-pressure (HP) fuel tubing leaks have developed during preoperational engine testing on Shoreham and Grand Gulf engines. There are no other reported failures in nuclear application.
3.2.14.3 Owners' Group Status Stone & Webster has analyzed the failed HP fuel tubing and has concluded that the failures originated in inner surface flaws that were initiated during fabrication. If, through eddy-current inspection, the inner surface condition of new tubing is found to be within the manufacturer's specification, Stone &
Webster has concluded the HP tubing is suitable for the service intended. It was also recommended, however, that all future replacement lines be of a superior material and be " shrouded" to protect against open oil sprays in the event of future leakages.
3.2.14.4 TUGC0 Status TUGC0 has decided to preceed with full replacement. Hence, no inspections were made on the original lines, which, h'aving given no previous difficulty at CPSES, were returned to temporary service. When the replacement lines, with shrouds, are received, they will receive the OG recommended inspections and subsequent monitoring. This is due to take place before fuel loading.
3.40 l
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i f
Upon the satisfactory installation and inspection of the replacement lines, TUGC0 concludes this component will be satisfactory for future EDG service.
3.2.14.5 pNL Evaluation and Conclusions PNL concurs with TUGCO, relative to both Train A and Train B.
3.2.15 Air Starting Valve Caoscrews Part No. Gg-032-114 Owners' Group Report Energency Diesel Generator Air Start Valve Caoscrew Dimension and Stress Analysis (SWECo April 1984) 3.2.15.1 Comoonent Function These capscrews bolt in place on the head of the air start. valves, which admit starting air to the cylinder. A failure, or an inappropriately long capscrew, will not keep the starting valve assembly in correct contact witn its seat, with consequential risk of damage as high-pressure combustion gases escape.
3.2.15.2 Comoonent Problem History '
No actual failures of these capscrews have been reported. However, on-May 13,1982, TDI reported a potential defect due to the possibility of the 3/410 x 3-inch capscrews " bottoming out" in the holes in the cylinder heads, resulting in insufficient clamping of the air start valves.
3.2.15.3 Owners' Group Status Stone & Webster and TDI both have recommended that the 3-inch capscrews be either shortened by 1/4 inch or replaced with 2-3/4-inch capscrews.
3.2.15.4 TUGC0 Status Upon receiving a 10.CFR 21 report from TDI in 1982, TUGC0 checked all cap-screws and shortened them as necessary. During the recent engine inspections, lengths were reverified, and torque checks were run after 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of operation.
The OG reconnended, in the supplemental report, that a sampling of cap-6 screws be checked for material- selection. TUGC0 will do so prior to fuel loading.
t 3.41
TUGC0 maintains that, subject to the material verification, these cap.
screws and their reinstallation meet TDI and OG requirements and are adequate for standby nuclear service.
3.2.15.5 PNL Evaluation and Conclusions The actions taken by TUGC0 to eliminate the potential interference would-appear to be adequate to prevent any subsequent failures, pNL concludes that, i with the continued use of TUGCO's installation procedures to control torque of bolts, studs, and screws to specified ranges, these components will not present future problems on the CpSES engines, and concludes these components--on Train A and Train B--are operable and reliable for their intended service.
3.2.16 Engine Mounted Electrical Cable part No. 02-688B Owners' Group Report SWEco No. OR4-210-013 3.2.16.1 Comoonent Function .
These cables serve the Woodward governor / actuator and the Air-pax magnetic pick-up, both mounted on the engines. Inappropriate cable materials, not able to withstand the temperature or service environment, could lead to short circuits, with adverse impact on the component functions and possible risk to personnel.
3.2.16.2 Comoonent problem History No failure of these cables has been reported. However, a TDI service information memo warned of potentially defective engine-mounted cables.
3.2.16.3 Owners' Group Status Analyses of the subject wiring, and of the recommended replacements, were conducted by Stone & Webster Engineering Corporation, both generically and spe-cifically for TUGCO. The replacement cable and terminations were deemed ser-viceable for this duty.
3.2.16.4 TUGC0 Status In response to the original service information, TUGC0 performed a complete review of all engine-mounted cable. All unsuitable cable was replaced 3.42
, - -4, - _- '
appropriately.
Based on this action, TUGC0 did not reinspect the cable during the recent inspection process. ,
TUGC0 concludes that the engine-mounted electrical cable at CPSES is suitable for its intended nuclear standby service.
3.2.16.5 PNL Evaluation and Conclusions Predicated on the evidence furnished, PNL concurs and concludes that the subject cables--on Train A and Train B--are serviceable for their intended use at CPSES.
9 4
I l
l 3.43
\s_
4.0 PHASE 2 COMPONENT REQUALIFICATION Toward the goal of requalifying the Train A and Train B engines, TUGC0 inspscted other significant engine components identified by the Owners' Group technical staff in Phase 2 of the OGPP implementation. This section describes the OR/QR inspection program conducted at CPSES and the results reported.
, PNL's evaluation of TUGCO's Phase 2 efforts is then presented, along with conclusions drawn from that evaluation.
4.1 TUGC0 PHASE 2 PROGRAM INSPECTION Train A and B engine inspections were performed in accordance with com-
~
ponent selection ans inspection plans developed by the Owners' Group speci- ,
fically for CPSES.
4.1.1 Insoection Procedures Procedures used in Phase 2 inspections were largely the same as those used in Phase 1. The inspection plans were carried out by TUGC0 maintenance person-nel following CPSES QA/QC procedures. These procedures included the prepara-tion of Maintenance Action Requests delineating the requalification action required. Components found to have indications were documented on TUGC0 Non-conformance Reports. These were subsequently dispositioned by TUGC0 engineer-ing and QA as to 1) use as is, 2) repair / rework, or 3) replace. Each replaced component was subjected to the same inspection protocol.
Results for Train A Phase 2 inspections are reported in George (June 7, 1984); Train B results are presented in George (June 29, 1984). These two documents are supplemented by a summary section in George ( August 15, 1984).
4.1.2 Results /TUGC0 Conclusions
, The complete list of Phase 2 component inspection results is given in Table 4.1. The Train A and Train B components 1ncluded in the inspection are ,
provided, along with an indication of whether the results were satisfactory or unsatisfactory; a blank indicates the component was not inspected.
4.1
TABLE 4.1. Phase 2 Component Inspection Results Train Item Part Number A 8 Lube oil fittings, internal header piping 02-307A S(a)
Lube oil fittings, internal header tubing 02-3078 S and fittings Lube oil fittings, internal header piping and tubing 02-3070 S
.; supports Crankshaft main bearing shells 02-310R U(b) y Crankcase assembly 02-311A S S Cylinder block, liner, and manifold nuts 02-315F U U Jacket water. inlet manifold coupling 02-316B S Water discharge manifold, coupling, and seals 02-3178- 5 Flywheel bolting 02-3308 5 Front gearcase gaskets and bolting 02-3358 S Piston rings 02-3418 5 Tappets and guides, intake and exhaust tappet 02-345A S assembly rollers .
S Tappets and guides, fuel tappet assembly rollers 02-3458 S S Camsha ft 02-350A S S Camshaft supports, bolting and gear 02-350C U S Idler gear assembly, crank to pump gear set 02-355A S S Idler gear assemoly, idler sears 02-3558 S S Idler gear assembly, bolting and gaskets 02-355C U Air start valve 02-359 5 U Cylinder head valves, int;se and exhaust 02-3608 U U Cylinder head valve cover gaskets 02-360C S Valve springs .
' 02-3600 S S Cylinder head subcovers, subcover assembly 02-362A U U i
Fuel pump, linkage / control shaft 02-371A S (a) S = Satisfactory (b) U = Unsatisfactory i
t 4.2 l
l
- . - _ . ., - , , _ , . ~ __ _ -
TABLE 4.1.. (contd)
Train Item Part Number A S Fuel pump linkage / bearings 02-3718 S(a) $
Intake manifolds02-375 U(b) y Exhaust manifold bolting and gaskets 02-3808 U U Cylinder block covers, gaskets and bolts 02-3858 S Cylinder block covers, gaskets and mounting hardware 02-3868 S S Rocker arms and push rods, intermediate / intake 02-390A U S rocker snaft assembly Rocker arms and push rods, exhaust rocker shaft 02-3908 S S assembly Rocker arms and pusn rods, -li fters 02-390F. U U Overspeed trip, governor and accessory drive 02-4108 U S ass emoly Overspeed trip couplings, flexible and spider 02-410C U S Governor drive gear shaft coupling 02-411A S S Governor drive coupling ,
02-4118 S S Governor linkage 02-413 U S Governoe assemely heat excnangers 02 415C S S Intercooler piping coupling 02-4368 S S Starting air distributor assembly 02 442A U Turbocharger bracket-air butterfly valve assembly, 02-4758 U S with actuator Turbocharger bracket, bolting.and gaskets 02-4750 V U Control panel assemoly terminal boards, switenes, 02-500N U U and wiring Lube oil sump tank, miscellaneous fittings, gasket, 02-5408 S pipe and valve bolting materials l ~
l
, (a) S = Satisfactory (b) U = Unsatisfactory
_ 4.3 A
e
+
All items listed in Table 4.1 that have at least one S and no V are considered satisfactory.by TUGCO. An 5 means that the component passed all the inspections without exceeding allowable criteria and that no repair or replace-ment was needed. A U denotes failure to comply with criteria in effect at the.
time of the inspection. In discussions with NRC and PNL, TUGC0 noted that some components (viz., air start distributor) could now be considered satisfactory because the acceptance criteria applied by TUGC0 at the time led to some compo.
nents being rejected that would be accepted under the OG criteria. When more than one unit of a component was tested and one of those units did not pass the inspection, the result was a U in Table 4.1.
In George (August 15,1984) TUGC0 provides summary details of the findings and disposition of the unsatisfactory findings for Train A and 8 components.
In evaluating the TUGC0 Phase 2 U components, PNL has elected to consider them in two categories: those U components with any conditions found that could influence the engines' function, and those U components considered to be less l
consequential. This subdivision is useful in reviewing the evaluation and I
conclusions provided in Section 4.2.2 of this TER. Tables 4.2 and 4.3 provide tne TUGC0 inspection results in these two categories, respectively.
4.2 PNL EVALUATION 4.2.1 Methodology The PNL evaluation is based largely on a review of the three documents describing the inspection plans and results (George June 7, June 29, and August 15,1984). This review is supplemented by a visit to TUGC0 on May 23 and 24, 1984, during which PNL and its consultants briefly reviewed the Phase 2 revalidation process. This included a sampling review of inspection plans and -
Nonconformance Reports and their disposition. Backup photographs and fi'es were viewed also.
4.2.2 Findings and Conclusions On the basis of information provided to date, the TUGC0 inspection proce-dures and acceptance criteria are considered adequate. The PNL sampling inspection of records suggests that adequate records are kept and that any 4.4 i
i
- _ _ . . . . . - - . - . ~ - - - - - - - - - - - - - - - - - - - - - - - - -- - - - - - - - - - - - - - - ^- - = ' ' - ~
TABLE 4.2. Defective Components That Could Significantly Affect Engine Operability / Reliability Comoonent/(TOI Part No.) TUGC0 Findings / Actions Crankshaft main bearing shells Train A - No.10 upper and lower shells (02-3108). This component supports were replaced because of indications and aligns the rer.< shaft, its that extended through the ba b{tt ayet-failure will lead to engine shutdown. lay into the base metal [LP, il VI,101 DISCJ].
Train 8 - No. I upper shell showed re-jectable linear indications and No.10
- lower shell was galled. Both were replaced with spares (LP, VI, 01).
Camshaft support bolting (02-350C). Train A - 16 bolt holes would not per-These bolts support the camshaft.
The engine can operate with some mit 1-1/4-inch bolts without bottoming out. New 1-inch bolts were installed bolts loosened but sufficient loss at all 16 locations. Sufficient thread of bolt support can lead to engine shutdown, engagementisprovidedwiththy}-inch bolts for for bolts,MAgqopertorqueing[TOS ' and VI for gear Cylinder head valves, intake and Nearly all valves showed evidence of exhaust (02-3608). These valves inadequate seating, scuffing or erosion control air into the cylinders and of stems and/or scuffing or pitting of exhaust out of the cylinders; minor leakage is tolerable. valve stem contact areas. Three valves required' replacement and the rest are being machined to fit the new cylinder heads (VI, DI, LP of stem / head blended radius).
Cyliader head subcovers (02-362A). Train A - three subcovers were replaced These elements support the rocker with satisfactory spares because of shafts and to is essential their structural engine integrity rejectable linear indications (VI, LP).
performance.
Train B - an unsatisfactory weld repair area was noted on the wee area of sub-
. cover 7L. Linear indications were also found by inspection on subcovers 7L, 6L and SR in the boss areas. These were replaced with satisfactory spares (VI, LP).
(a) LP = liquid penetrant inspection VI = visual inspection O! = dimensional inspection TO = torque verification -
e MA = material verification 4.5 t
i .
.. . _ - , , , . _ , - - , _ - _ - _ _ - - - - - - . -- - - _ _ __-_m._.--__,.-.-#,__-._,_m , _ - . - - . _ -r, ,- ,-- -
TABLE 4.2. (contd)
Component /(TOI Part No.) TUGC0 Findings / Actions Intake helps flange Manifolds (02-375).
support manifoldThe andelbow Train A - intake manifold elbow no. 8L had a corner broken off of the head seals gasket. Leakage will degrade flange and was repiqced with a satis-engine output. factory spare [VIt ai],
Train B - intake elbow 8R was replaced with a satisfactory spare because of two broken-off corners and elongated bolt holes (VI).
Rocker a'rms, intermiediate rocker Train A - chips or linear indications shaft assemoly (02-390A). This in three intermediate rocker arms assembly transmits cam motion to resulted in replacement with satisfac-valves and its operation is essential tory spares for two rocker arms and to engine operation. re MA{ugbishment C ]. of tne other [VI, 01,(D)
Starting air distributor assembly Train A - both assemblies were replaced (02-442A ) . This assembly sends starting air to cylinders. because of " excessive wear" (VI).
It is essential for startup.
Turbocharger bracket, bolting and Train A - 24 bolts on the right bank gaskets (02-4750). This bracket s,upports the turbocharger. Some were found to have insu'fficient thread engagement, and were properly retorqued.
missing bolts can be tolerated; One bolt was replaced with a modified however, loss of turbocharger bolt because of stripped bolt hole seriously reduces ea gine power. th reads . Missing lockwashers wera lso replaced wnere necessary [VI, VID(og],
Train B - five bolts without grade 5 markings were replaced with grade 5 bolts.
l (a) VI = visual inspection (b) DI = dimensional inspection .
(c) MA = material verification (d) VID = visual inspection of identification markings ,
4.6
TABLE 4.3.
~-
Defective Components That Will Not Significantly Affect Engine Operability / Reliability Component /(TDI part No.) TUGC0 Findings / Actions i Cylinder Block, Liner and Manifold Nuts (02-315F) Train A - 48 of 128 nuts had no identi-fying marks. LP was satisfactory and e a all
[VI,tal nuts TO, wer(b)reigs'J)lled (psc ,
in the engine Train B - four nuts on cylinder head No. 8R had forging laps extending across the flat onto the machined face, and were replaced with satisfactory spares.
Idler Gear Assandly (02-355C)
Train B - because of a number of dif.
ferent markings and lengths on camshaft cover and idler gear cover bolting, all -
bolts have been replaced with 1-1/4-inch grade 5 bolts to ensure uniformity (except for four camshaft cover bolts which shorter require hole depths) 1-inch(VI,bolts 01, VIDi becaus9 d'
g]f Air Start Valve (02-359) Train B - a layer of caroon deposition was cleaned from the valves (VI, DI, TO).
Exhaust Manifold Bolting and Train A - one bolt was too long, one Gaskets (02-3808) ,
bolt was of the incorrect material, and two bolts were damagec. All four of these bolts were replacad with satis-factory bolts of the new socket head type (TO, DI, VI).
Train B - nine bolts were found to be of incorrect length. All of the bolts on Train B are being replaced with the
. latest TDI socket head tyoe. Only 48
. were available for reassembly; however, the remaining 16, which are satis-factory, will be replaced later (DI, VID).
(a VI = visual inspection (b -TO = torque verification (c LP = liquid penetrant inspection (d) V!D = visual inspection of identification markings 4.7
TABLE 4.3. (conto)
Component /(TDI Part No.) TUGC0 Findings / Actions
- Valve lifters (02-390F) Train A - four lifters did not pass the leak down rate test and were reglaced with
, LP(b)3,satisfactory spares [VI, tai Train B - 32 of 6411fters did not pass the leak down rate test. 57 satisfac-tory spares were available and were installed with 7 of the original satis-factory lifters (VI, LP).
Overspeed Trip, Governor, and Train A - a missing locking clip on one Accessory Drive (02-4108) bolt and a missing lockwire on one coy MA'g}ing capscrew were replaced (OI,(C) on shaft].
Overspeed Trip Coupling (02-410C) Train A - coupling spider showed some peeling and couplings had some nicks.
. Spider was replaced with a satisfactory spare .and the couplings were refur-bish ed. Neoprene peeling on the spider was caused by burrs or discontinuities on the coupling, which were removed.
A missing setscrew was also replaced (VI).
Governor Linkage (02-413)
Train A - some rust, but no pitting, was noticed on the linkage. Rust was removed prior to reinsta11ation (VI).
Tureocnarger Bracket - Air Train A - rignt bank shaft snowed some Butterfly Valve Assemoly (02-4758) pitting at 3 lo bisned (VI, VID{ajions ' ]. and was refur-Control Panel Assembly (02-500N) Train A and Train B - cleaning of
' assembly was required (VI).
(a) VI = visual inspection (b) LP = liquid penetrant inspection (c) O! = dimensional inspection (d) MA = material verification (e) VID = isual inspection of identification markings.
4.8 '
-~ .-, a- . - .. - - . . . . - . - -.
component's history can be reconstructeo. It is noted that the TUGC0 OR/QR reports have not been issued as of this date, so the PNL evaluation does not provide conclusions relative to the Phase 2 revalidation program for the CPSES.
. Consequently, the adequacy or completeness of the canponents selected by the Owners' Group for the CPSES Phase 2 revalidation program is not evaluated here.
PNL has concluded that interim licensing action is not contingent upon the OG Phase 2 completion (Pacific Northwest Laboratory June 1984, p.10). In review-i.'G the Phase 2 component revalidation, PNL noted that TUGC0 states that they have addressed 45 components (George August 15, 1984, p. 5), whereas only 44 component findings are reported. In a telephone conversation with NRC, TUGC0 reported that 44 is the correct number due to the method TUGC0 later used to account for the wrist pin (as part of the connecting rod).
4.2.2.1 Satisfactory Components PNL notes that there are components found satisfactory by TUGC0 for one engine but not inspected for the other engine. In those cases it is PNL's judgment that that same component in the other engine need not be inspected.
The probability for significant findings is considered small. PNL considers all components found satisfactory are adequate to perform their intended function both for Train A and Train B.
4.2.2.2 Defective Components That Could Affect Engine Operability / Reliability In general, the TUGC0 Component Revalidation Checklist and accompanying OA Inspection Plans do not provide any indication of the underlying cause for ne rejectable indications reported. Presumably this will be supolied in the OR/0R submittal to NRC. In the absence of TUGCO's presenting a definite cause (PNL acknowledges that in many instances the cause may be indeterminable and uncon-sequential), PNL consultants have applied judgment, based on experience with
, other engines, to evaluate the adequacy of the TUGC0 actions to renedy tne problem.
Two items, camshaft bolting (02-3506) and turbocharger support bolting (02-4750), appear to be assembly errors. No further problem is anticipated following the TUGC0 repair / replacement actions. PNL notes that the camshaft 4.9
, +
bolting problem is not the same problem encountered at the Shoreham Nuclear Power Station where cracks occurred in a region of the ' block that supports the camsha ft. This region is different in the straight and vee engine designs.
However, failure of any bolts or threads can have serious consequences.
The main bearing shells (02-3108), rocker arms (02-390A), and subcovers (02-362A) all had generally minor indications. No cause was supplied by TUGCO.
In view of the low number of operating hours, and based on previous experience, PNL consultants believe manufacturing defects (especially the faulty weld repair in the subcover) or minor abrasives in the lubricant could cause the indications noted. All replacement parts were inspected to the Owners' Group specification. PNL judges the possibility of recurrence to be small, and considers TUGCO's actions adequate for these components to serve their intended functions.
- Intake and exhaust valves (02-3608) showed more than normal surface distress but no fundamental weakness. The pattern of poor seating could inci-cate poor QA/QC procedures in manufacturing. The scuffing or scoring of the chrome is . common and of little concern. PNL considers TUGCO's actions appropriate and adequate for these components to serve their intended functions. . .
The intake manifold flanges (02-375) on both Train A and Train B engines were found to have broken corners and, on Train B, the bolt holes were found to be elongated. No explanation was presented in TUGCO's comprehensive recort (George August 15,1984), but in a subsequent telephone communication to NRC dad PNL, TUGC0 noted that the corner breaks were minor and of no significance to the serviceability of the flanged connection. On the basis of this explanation, PNL concludes these components are serviceable.
B.oth standby air distributors (02-442A) on the Train A engine exhibited
, excessive wear" and were replaced. This raised the concern of PNL, in that a similar inspection of Train B was not conducted. In a later telephone com-munication to NRC and PNL, TUGC0 advised that the condition of the components was subsequently checked with the Owners' Group due to uncertainty on inspec-tion standards. TUGC0 was advised that the wear encountered was normal; hence, Train B was not inspected.
l 4.10
PNL noted that failure of a starting air distributor would compromise engine reliability. Because the wear was deemed excessive at the time by TUGC0 inspection personnel, after only 67 starts onsite, PNL remains concerned and recommends that dist'ributors on Train B be inspected before the Train B engine can be considered qualified for nuclear service.
4.2.2.3 Defective Comoonents That Will Not significantly Affect Engine Operability / Reliability PNL has reviewed t5e significant indications reported by TUGC0 (see Table 4.3) and believes tnat the actions taken by TUGC0 are adequate. PNL concludes that the repaired and replacement parts will serve their intended fuaction in the Train A and Train B engines.
e i
e 8
+
I 4.11
5.0 PROPOSED MAINTENANCE, INSPECTION AND SURVEILLANCE PROGRAM While evaluating the Owners' Group Program Plan, PNL recognized that a comprehensive maintenance and surveillance (M/S) program would be a key aspect of the overall effort to assure future TDI diesel engine operability and reliability, and so stated _ in its formal review of the OGPP (Pacific Nortnwest Caboratory June 1984). Recognizing that the Owners' Group Program Plan had not yet specifically addressed M/S activities, PNL reconenended that the Owners'
. Group develop a definitive M/S program (in consultation with TDI), and that detailed plans based on those Owners' Group reconenendations be developed for each engine installation by the individual owners.
The need for an enhanced M/S plan was further identified for nuclear stations seeking licensing actions prior to the completion of all elements of tne OGPP (Pacific Northwest Laboratory June 1984, Sec. 4.0). Some elements of such an ennanced M/S plan were initially identified by PNL in letters of
. April 16 and 17,1984, to C. Berlinger at NRC-(dealing specifically with Mississippi Power & Light's Grand Gulf Nuclear Station). The features of tne enhanced M/S program suggested by PNL were subsequently incorporated by the NRC staff in a letter to MP&L dated April 25, 1984, re: " Evaluation of tne TDI
$ Diesel Generator Reliability for Power Operations at GGNS."
In a letter (Youngblood August 2,1984), NRC requested that TUGC0 describe tneir ennanced M/S program. This section reviews TUGCO's response. This review responds to the information supplied to date by TUGCO. The review is not intended to address the broader issue of adequate s'urveillance and maintenance that is being addressed by the Owners' Group. It is cons'idered likely that additions / modifications to the M/S program will be required following the OG reconenendations.
, 5.1 MAINTENANCE AND INSPECTION PLAN TUGC0 has reviewed the OGPP Phase ! M/S recommendations and revised their CPSES Unit 1 M/S schedules as documented in George (August 15,1984).
l
, 5.1
Section 8. "CPSES Unit 1 Diesel Generator Preventa.tive Maintenance and Surveillance Program" is the specific reference in George (August 15, 1984).
5.1.1 Elements and Rationale Tables 5.1 and 5.2 present a comparison of TUGCO's proposed maintenance schedule, the earlier NRC guidance, and current PNL recommendations. Items are arranged in the same sequence philosophy as used in Section 3.0 of this TER (viz., structural components; power train components; ancillary and auxiliary -
components and systems; and generally from the bottom of the engine to the top).
5.1.2 PNL Evaluation and Reconenendations The TUGC0 M/S proposals do provi-de coverage of a number of items and systems considered key to maintaining engine operability and reliability. They should be deemed applicable to each engine. However, in reviewing TUGCO's pro-posals, PNL noted several important components and systems that were not incor-porated in the list, as well as areas where TUGCO's proposal should be revised.
The items listed in both Tables 5.1 and 5.2 are deemed by PNL to deserve per-todic observation, evaluation, and maintenance, as appropriate. PNL's recom-mendations presented in Tables 5.1 and 5.2 related to maintenance actions beyond the first refueling cycle, (i.e., PNL concurrence with TUGCO's long-range maintenance plans) are necessarily tentative.
PNL feels that NRC should require that the items listed in Table 5.1 be incorporated into TUGCO's surveillance and maintenance program. These are:
e foundation and foundation bolting e rocker arms, push rods, tappets, e engine block and base cams, and camshaft e crankshaft e gear train e main bearing shells e turbocharger e connecting rods ,
e air start valves e connecting rod bearing shells e air start distributor filter e pistons e studs and fixtures e cylinder liner o jacket wat,ey pump
- cylinder head e lube oil duplex filter e cylinder valve springs and e lube oil check. 3 hydraulic lifters 5.2
s TABLE S.I. Comparison of TUGCO's Proposed Maintenance Plan: Items That Should Be incorporated into TUGCO's Plan Component NRC Guidance (April 25) TUGC0 Proposal (August 1) PNL Recommendations foundation & '
Check for bolt preload Concur with TuGC0 Foundation NOTE: Sole plate and groot Bolting to be inspected at this time (every refueling outage)
Engine Visually inspect af ter (not listed by TUGCO, but Block 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> operation or Visually inspect daily during committed to OG plan) operation; with intensely and Base monthly lighted inspection monthly, while operating. Eddy cur-rent tests as specified by OG.
Inspection of the camshaft sup-port in the galleries at times of saintenance.
(n Crankshaft Hot and cold every Hot and cold deflection
- 6 months; hot within Once each refueling cycle; measurement (every refuel- hot to start in 15 minutes, 15 minutes of shutdown ing outage) complete within 30 minutes Main Bearing Visual exam and dimensional Sampling and inspection Shells verification of thickness. procedure to be developed from NOTE
- The procedure for from Owners Group and/or two this inspection includes highly loaded bearings at cleanliness and bolt pre- every 2nd refueling outage.
Ioad requirements (every 2nd refueling outage)
Connecting Visually inspect and (Not listed by TuGCO)
Rods retorque after 24 Visual surface inspection of starts, 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> of external surface and bolt pre-operation, or 6 months, load check each 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> or 9 months, whichever is first whichever is first
TAflLE 5.1 (contd)
Component NRC Guidance (April 25) 10G00 Proposal (August 1) PIE. Recommendations Connecting Rod Heasure bearing clearance. Pull 2 sets of pistons-examine bump method. NOTE: Inside conrod bearings (at first Bearing of engine will be examined Sheils refueling outage) for abnormal conditions during this time (every Measure bearing clearance refueling outage) (every refueling outage)
Pistons (not ilsted by TuGCO) Pull 2 sets of pistons for examination; all others visual bottom side exam (boroscope)
(first refueling outage)
Cylinder Liner Boroscope inspection (every Visual (every refueling outage) refueling outage)
Measure / record (every dis-assembly / overhaul)
Cylinder Alr-roll 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after (not listed by TUGCO)
Heads engine runs and each Air-roll 4 to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> after day thereafter engine runs, and again after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and prior to planned starts. Inspect four heads at first refueling.
Cylinder Valve Visual exam for proper Springs and Concur with TUGC0 operation and adjustment Hydraulic Lifters (every refueling outage)
Rocker Arms. V'sually check after Visually check at each i Push Rods, Visually check (at each refuel-Tappets, pre-operational testing refueling outage ing outage) and af ter each 24 imurs
- Cams, Camshaft of operation 9
4-
9 TABLE 5.1. (contd)
Component 'NRC Guidance (April 25) TUGC0 Proposal (August 1) PNL Recommendations Gear Train 1) VI.sual check of tube oil Visual (every outage) spray jets ano visual exam of gears (every refueling outage)
- 2) dimensional verification Backlash and thrust (every 2nd of backlash and thrust refueling outage)
(every 2nd refueling outage)
Turbocharger 1) Teardown, check rotor Concur with TUGC0 float and stationary nozzle ring bolts (after 40 auto starts or 100 starts or first refueling outage, whichever comes first)
- 2) Teardown, includes visual
<n exam of all major components In verification of bearing running clearances, blue check of thrust bearing and
, replacement of nozzle ring bolts (every 3rd refueling 2 outage)
Air Start Teardown, with visual exami- Concur with TUGC0 Valves nation; verify valve seat contacting; refurbish as required. Each refueling cycle Air Start inspect; clean. Replace Concur with TUGC0 Distribution as required each month.
Filter
TABLE S.I. (contd)
< Component NRC Guidance (April 25) ItMICO Proposal (August 1) PK Recommendations c
Studs and Spot check 251 monthly Air start valve capscrews Check 100% of air starts Fixtures for torque 1001, re-torque after a valve capscrews and 25% of minimum of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of all other items at each
! running whenever bolts refueling outage are disturbed Jacket Train A and B - disassemble /
Water Pump examine for shaf t galling, worn wear rings, warped backing plate (first refueling outage)
Lube Oil Drain sludge or water each Concur with TUGC0 Duplex Fliter 3 months. Inspect, clean; replace as required at
- pressure drop of 20 psig, or each refueling cycle, whichever is first Lube Oil Check for water follow- Sample. This sample is Check for water following Check ing pre-operational taken during the monthly pre-operational tests, then
- tests, then weekly surveillance test at the monthly or after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />
! or after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of inlet to the lube oil of operation, whichever is
- operation whichever is filter. NOTE
- Sample first. Check for chemical i first. Check monthly sent off-site for full and particulate contamina-for contaminants and spectro-chemical analysis tion on same schedule. The water in sump; check (monthly) sample should be collected filters while the engine is running.
Check filter pressure drop hourly during operation 1
9
The maintenance items noted in Table 5.2 are considered to be good prac-tic 1. PNL feels they should be carefully considered by TUGC0 in establishing its maintenance plan; however, pNL is not recommending that NRC require TUGC0 to incorporate them into its maintenance-program. These items are:
e fuel injection pump e fuel oil duplex strainer (02-825E) e fuel injection nozzle e lube oil sung tank e fuel pump and governor linkage e lube oil heat exchanger e governor e lube oil keep wann filter
- e air start valve admission e lube oil strainer valve strainer e Jacket water system o intake air filter e jacket water heat exchanger e fuel oil drip tank e engine performance.
e fuel oil filter; fuel oil duplex strainer (02-4558) i Since issuing their Comprehensive Reoort (George August 15,1984), TUGC0 1
- has informed NRC and PNL that a comprehensive M/S plan will be published l
shortly by the Owners' Group. TUGC0 will adopt it, as appropriate, in lieu of 1 their current proposal. PNL believes that this should be' reviewed with the i idea, as a minimum, of incorporating the PNL recommendations outlined in l
Tables 5.1 and 5.2 if they are not included in the OG plan.
l The following sections provide PNL recommendations and the supporting dis-
! cussion relative to the M/S plans presented in Table 5.1 where P.VI, recommenda-tions differ from TUCCC plans.
5.1.2.1 Engine Block and Base TUGC0 provides no maintenance plan for the engine block and base.
A vee engine has three primary structural components: the base, the l cra'nkcase, and the cylinder block. The history of problems in the population l .
of TDI engines as reported by the Owners' Group, and relevant analyses by TOI and the Owners' Group, lead PNL to conclude that there is no significant likelihood of failures to occur in the base and crankcase in external locations where they are visibly discernible. However, there has been a substantial history of cracks on the top of the cylinder block, some of which are visibly i
l 5.7
- - - - - , - . . . . - . , - - - - . g- - . , - - , - , . , , ,.-.,..,..,,y,mw.,,,,.,y, y - - - - . . . - , - , - - - , - - - - . - -n e-
TA8tE 5.2. Comparison of IUGCO's Proposed Maintenance Plan: Items to be Considered in Establishing IUGCO's Plan Component 'NRC Guidance (April 25) TUGC0 Proposal (August 1) Plt. Recommendations Fuel Teardown, includes visual Verify calibration / operation
- lajection exam, vertitcation of dimen- (every 3rd refueling outage)
Pump stons and refurbishment as required (every 2nd refuel-ing outage)
Fuel Teardown, includes visual Check popping pressure and injection exam of contact surfaces, spray pattern characteristics Nozzles setpoint verification and (every refueling outage) refurbishment as required Fuel Pump Inspect and lubricate Inspect and lubricate
) and Governor (yearly) (monthly) l L inka _e on Governor Change oil (every refueling Concur with TUGC0
- La outage)
Air Start inspect; clean as required Concur with TuGC0 Admission each 3 months i Valve Strainer .
! Intake Inspect, clean; replace as Concur with TUGC0 Air Filter required; each 6 months i Fuel Oil Drain and clean; each Check monthly; drain and i
Drlp Tank refueling outage clean as required j Fuel Oil Inspect, clean. Replace as Concur with TUGC0 Filter; Fuel required. At pressure drop Oil Duplex of 20 psig or each refuel-i Stralner ing, whichever comes first
- (02-45S8) -
O d
S I
i . . ,
IABLE 5.2. (contd)
Co--- :;t NRC Guidance (April 25) TUGC0 Proposal (August 1) PNL Recommendations Fuel Oil In;pect, clean as required Concur with TUGC0 Duplex Strainer (each refueling cycle)
(02-825E)
Fuel Oil Inspect, clean as required. Concur with TUGC0
. Transfer At pressure drop of 7 psig Pump or each refueling cycle, j Strainer whichever comes first '
Lube Oil Clean and inspect each Concur with TUGC0
, Sump Tank refueling cycle i
Lube Inspect, clean as required. Concur with TUGC0 ta Oil Heat Every 2nd refueling cycle u) Exchanger Lube Oil inspect, clean or replace Concur with TUGC0 Keep Warm as required. At pressure Filter drop of 20 psig or each refueling outage, whichever is first Luhe Oil Drain sludge or water each Concur with TUGC0 Strainer 3 months. Inspect, clean; replace as required at pressure drop of 20 psig, or each refueling cycle, whichever is first-bd i
- 1 4
4 1
TABLE 5.2. (contd)
- Component -NRC Guidance (April 25) TuGC0 Proposal (August 1) Pit. Recommendations Jacket Water Check pH, conductivity and Concur with TUGC0 System corrosion inhibitor each month Jacket Water Inspect, clean as required Concur with TUGC0 P Heat' Exchange.- each 2nd refueling o, . , f
- Er.gine ,-
Cold compression check; Concur with TUGC0
- ' . Performance '_ ,,' ,
maximum firing pressure check. Each refueling.
4 9
e
discernible and/or detectable by NDE methods without head removal. The Owners' Group generic issua report (FaAA-84-15-12) calls for careful surveillance of this surface on certain engines, but at unspecified intervals.
TUGC0 did not address the routine inspection /maintenant of the engine block and base.
In light of the histor,y of block cracks at CPSES, the FaAA analysis, and
~
the unresolved status of indications at 4R and SR (Train A) and 1R and 4R (Train B), PNL agrees with TUGC0 that there remains legitimate reason to maintain enhanced surveillance of the blocks, at least through the first opportunity for heads-off reinspection and until a more definitive resolution of the problem is established by the Owners' Group and TUGCO. Furthermore, because of 'the problems encountered in the inline engines, PNL feels it would be prudent to inspect the cylinder block camshaft gallery in the vicinity of the camshaft support at each maintenance interval, pNL Recommendation In addition to the inspections recommended by the OG and committed to by TUGCO, pHL recommends routine daily visual inspection of the block and box external surfaces during operating periods, with a more thorough inspection under strong lighting at lesst monthly. These should be conducted while the angine is operating.
pML also recommends that, at the first refueling outage, the respective indications noted in Trains A and B should be reinspected for propagation, and that OG recommendations for heads-on eddy-current testing (or approvec suo-stitute) be followed (to which TUGC0 has cannitted).
5.1.2.2 Crankshaft Deflection Checks
' TUGC0 proposes hot and cold crankshaft deflection checks each refueling outage, but does not commit to a time.after engine shutdoun to initiate and complete these checks.
Two purposes are accomplished in crankshaft' deflection checks:
e detection of gradual shifts in shaft support internal to the engine (most likely being significant bearing deterioration) 5.11
e detection of changes in external engine support, as in the concrete foundation, or a shift of shims between the foundation rails and the engine base plate. (The foundation will change shape with prolonged engine operation, tending to hump toward the middle due to thermal growth, which must be corrected by appropriately shimming the engine.
It may also undergo long-term permanent change as chemical processes continue within the concrete.)
PNL Recommendations PNL reconnends that TUGC0 take hot and cold deflection readings at every refueling outage. The hot deflection checks should be taken immediately after the 24-hour preoperational testing, so as to reflect representative operational foundation temperatures. The hot checks should be initiated within 15 to 20 minutes after shutdown, and completed as rapidly as possible, preferably within 1/2 hour, starting with the last throw of the engine (generator end).
Sucn a schedule, although strenuous, is deemed achievable.
5.1.2.3 Main Bearing Shells -
TUGC0 oroposes to inspect all shells at every second refueling outage.
PML recomumends a sampling inspection following disassembly / overhaul.
In general, the main bearing shells on the CPSES. engines have not been a problem area. Four bearing halves were replaced due to linear and galling indications; the remainder were deemed acceptable for use. TUGC0 proposed a visual exam and dimensional verification of all bearing tnicknesses every second outage. This is not consistent with the amount of disassemoly being propcsed on otner components of the engine that have to be removed for access to the main bearings.
PNL therefore feels that, although the TUGC0 proposed maintenance is
^
acceptable, this frequency and magnitude of inspection may engender unwarranted engine unavailability. PNL feels the maintenance plan should be develcped as a function of experience in this application. Factors taken into account should recognize the greater than normal function of wear due to minimal lubrication that c: curs during the starting and stopping cycles of the engine.
5.12 l
PNL Recommendations i A sampling and inspection pecgram should be developed from the Owners' Group information. For the interim, two highly-loaded bearings (identified in FaAA reports as Bearings 5 and 6) should be inspected at each second refueling outage. Associated caps and saddles should be checked also.
5.1.2.4 Connecting Rods TUGC0 provides no maintenance plan for the connecting rods. PNt. recom-mends visual inspection of connecting rod boxes and checks of bolt preload
. every 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> of operation or 9 months, whichever is first.
In light of the history in the TDI engine population (however limited) of connecting rod link-rod box cracking, bolting problems (viz., some galling, some preload relaxation, some failures), and fretting along contact areas of the serrated teeth, some regular visual inspection and bolt retorquing (or equivalent checking) is deemed warranted. The relevant Owners' Group generic issue report (FaAA-84-3-14) recommends that the interval on bolt retorquing not exceed 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> of operation at full load (i.e., manufacturar's rated load),
248 hours0.00287 days <br />0.0689 hours <br />4.100529e-4 weeks <br />9.4364e-5 months <br /> at 85". load, or 285 hours0.0033 days <br />0.0792 hours <br />4.712302e-4 weeks <br />1.084425e-4 months <br /> at 75% load. In making that reccmen-dation, FaAA provided no differentiation between connecting rods having 1-1/2-inch bolts and those with 1-1/.8-inch bolts. Although the history of 1-1/2-inch bolting is reportedly better, it apparently is not totally devoid of problems (either experientially or analytically). Thus, even by the Owners' Group's own analysis, the establishment of an enhanced sueveillance plan is deemed prudent.
]
TUGC0 does not propose any surveillance for the connecting rods or bolting systems. Recogni:ing that TUGC0 reassembled the connecting rods before
. verification of tooth contact could be made, it is recommended that a definite surveillance plan (e.g., external inspection and checking bolt torque) should
, be in effect.
PNL Recomendation PNL recommends visual inspection of all rod box external surface areas and bolt preload check each 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> of operation after post-inspection reassemoly or 9 months, whichever occurs first.
5.13
_ e. - - - . - _ ,. s , _ , . . _ . . , ,
l l
As compared to NRC's original proposal and the Owners' Group recom-mendations, this approach should conservatively address the load levels for LOOP and LOCA events for CPSES's units, as well as all preoperational testing following engine reassembly, and the possible impacts of low-cycle fatigue associated with a multitude of starts. At the same time, this revised pattern will reduce the cumulative downtime required, thereby enhancing engine availability.
5.1.2.5 Connecting Rod Bearing Shells TUGC0 proposes to measure bearing clearance at every refueling outage.
PflL recommends a sampling inspection of bearings themselves, as well as bearing clearance, at each refueling outage.
The Owners' Group Phase I deJign review report (FaAA-84-3-1) concluded that the bearings were adequate at site loads for up to 38,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />, or ten times the lifetime expected usage. TUGCO, in turn, has based its inspection l criteria on these findings. PNL is not in complete agreement with this ontlosopny due to the duty cycle of the engines and the high number of starts ~
they will experience.
Each engine start effectively influences the rate of wear (increased) between 10 to 100 times the normal rate of wear on the bearings. In addition, l putting the engines on high loads soon after starting also increases bearing wear rate more than does a more relaxed load application. Thus, the bearing wear may easily exceed the predicted rate. TUGCO's approach, therefore, requires modification to allow for visual inspection of bearing sets that may be suffering from galling, wiping, cavitation or load-induced damage. This can be a sensitive area with aluminum bearings.
pML Recommendations PNL recommends inspecting these bearings (two sets of pistons) by visual and radiography methods at-the first refueling outage; obtaining product oil contamination analyses; and monitoring bearing clearance at every refueling outage.
l 5.14 l
1
, 5.1.2.6 Pistons TUGC0 provides no maintenance plan for the piston skirts. PNL recommends a sampling inspection at the first refueling outage.
{
The family of piston skirts (AN, AH, AF, AE) in the R.4 series of engines has experienced various types of failures. The Owners' Group discovered this history when the structural integrity of the AF and AE piston skirts was investigated by Failure Analysis Associates (FaAA-84 214). TUGCO's EDG units were originally furnished with type AH piston skirts, which have subsequently been replaced with AE skirts. Several of the new retrofitted and installed AE pistons required relief grinding due to crack / linear indications. The AE piston experience is limited to one location in Alaska, which has not been subjected to a full inspection with documented results.
TUGC0 did not address maintenance level or interval.
PNL Recommendations PNL recommends that two sets of pistons (four pistons) be disassemoled at the first refueling outage and inspected for crack indications per procedures recommended by the Owners' Group.
5.1.2.7 Cylinder Liners TUGC0 proposes boroscope inspection at every refueling outage. PNL concurs and recommends dimensional check for wear at every disassembly. ~
Cylinder liners now installed in CPSES Unit I were machined and honed prior to installation of the type AE piston skirts. In addition, dimensional verification was satisfactory.
Pending the Phase II report by Failure Analysis Associates on the liners, they are considered acceptable.
' However, TUGC0 did not indicate any measurement of wear on the liners.
Beca,use liner wear provides an important indication of engine operability and reliability, it should be monitored whenever possible.
5.15 i
O 9
1 pNL Recommendations All liners should be visually inspected at each refueling outage, to check for any scuffing or metal deposition. In addition, the liners should be measured for wear at every disassembly, and the dimensions recorded for trend analysis. .
5.1.2.8 Cylinder Heads TUGC0 provides no maintenance plan for the cylinder heads. PMt. recosamends a schedule of engine air-rolls to detect water leakage.
Air-colling the engine is done to detect water in the cylinder, which would indicate a cracked cylinder head (or liner), with water not drained to crankcase. Any substantial water accumulation in a cylinder could lead to severe damage to head, piston, crankshaft, and/or bearings on engine startup, and could seriously impact engine operability. TUGC0 has not addressed this in their proposal.
PNL Recommendations PNL recommends a schedule for air-rolling, as follows:
e an initial air-coll at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> (but not over 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />) after engine shutdown e a second air-roll approximately 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after shutdown e thereafter, an air-coll immediately prior to any planned engine operation.
The basis for the change from the earlier NRC guidance, based on PNL recommendations (which called for air-colling the engine every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />), is tr.0 recognition that, if a leak of substantial, detectable proportions has not occurr'ed within the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of cooldown, it is unlikely that one will
- develop before the next engine operation. However, because it is still possible, although not likely, for a small leak to seep and accumulate (i.e.,
the water be retained by the piston _ rings), it rem?"1s prudent to check for the presence of water before any planned start.
5.16 t
i
t l l l t
The desirability of air-colling the engine was further substantiated recently by the occurrence of just such a leak, detected by barring-over the l engine, at Grand Gulf Nuclear Station.
PNL also recommends removal of four heads and visual and LP inspection of the firedeck at first refueling.
5.1.2.9 Rocker Arms, Push Rods, Cams, Camshaft TINIC 0 proposes visual checks at each refueling outage. PflL concurs, diffaring siightly fras 11RC guidance.
Engine operability is affected by defects in push rods, cams, tappets, and other similar components and their supporting structures. Some of these components at CPSES have shown indications. Hence, regular visual inspection is needed, although few operating hours are anticipated. The difference between the NRC guidance (after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of operation) and the TUGC0 proposal is not considered significant, in light of the low wear rate or limited likelihood of structural failure for these components, for two reasons: 1) all parts wilhave been inspected recently and 2) in the opinion of the PNL consultants, very little change in the condition of these parts is expected during the 50- to 200-hour operating time involved in the CPSES operation.
PNL Reconsnendations PNL considers the TUGC0 proposal acceptable.
5.1.2.10 Fuel Injection Pumas %
TUGC0 proposes refurbishment at every second refueling outage. PNL recommends in addition a calibration / operation check at each third refueling outage.
Fuel injection pumps on the CPSES Train A and B engines have not been a source of problems. TUGC0 proposes to completely disassemole all pumps at every second refueling outage. Due to the precision and close-tolerance nature of the fuel injection pumps, they can easily be damaged during a disassembly, thus requiring replacement of parts when otherwise ur.necessary. Fuel injec-tion pumps can be checked for proper operation and calibration at any reliable diesel service center; faulty or questionable pumps can then be put aside for 5.17
._ 1-~ _ ___
disassembly. It is important to note that the same test snould be performed on all pumps after reassembly, should they be disassembled.
i pNL Reconmendations
- - pML does not otherwise object to pump inspection every second refueling cycle, but suggests TUGC0 verify calibration and operation of all fuel injec-tion pumps at every third refueling outage. Should other tests or operating surveillance (i.e., cylinder firing pressure or exhaust temperature) indicate a potential fuel pump problem, verification of the suspect pump should be per-
- formed at that indication.
5.1.2.11 Fuel Injection Nozzles TUGC0 proposes refurbishment as required. PNL recomumends that " popping" bressure and spray pattern checks be performed at each refueling outage.
Fuel injection nozzles are similar to injection pumps, in that very close tolerances are encountered; thus, they are also susceptible to damage during maintenance inspection, proper testing of the nozzles for leakage, " popping" l pressure, and spray pattern would give a complete indication of the status of each nozzle. Then, only nozzles giving questionable results would need to be disassembled. The same tests should still be per' formed on all nozzles after reassembly, should they be disassemoled, pNL Recommendations pNL recommends checking " popping" pressure and spray pattern of all fuel injection nozzles at every refueling outage. Should operating surveillance (i.e., cylir. der exhaust temperature) indicate a potential fuel injection nozzle problem, the suspect nozzle should be tested and, as necessary, disassembled.
5.1.2.12 Fuel Pumo and Governor Linkage TUGC0 proposes yearly inspection / lubrication. PNL recomumends weekly inspection and monthly lubrication.
Rusted / pitted fuel pump and governor linkage can result in unstable engine load and speed response. Considering the potential for high humidity 5.18 l -
- l associated with plant siting and the relatively long-term standby periods, it would be prudent to perform a walk-around inspection utilizing a high intensity light to examine linkages.
PNL Recomendations Perform weekly visual inspections and apply lubricant as required, typically during the m'onthly testing period.
5.1.2.13 Studs and Fixtures The TUGC0 maintenance plan addresses only air start valve capscrews. PNL recomumends also that other studs and fixtures be maintained or a sampling basis at each refueling outage.
Loss of preload on cylinder head studs, rocker arm capscrews, and air start valve capscrews can adversely affect engine operability if it goes unnoticed. The generally positive experience at CPSES in this regard warrants a less rigorous schedule of checking.
PNL Recommendations PNL recomends a 25%-sample check of head stud and rocker arm capscrew preload at each reactor refueling outage. However, because the air start valve capscrews are more susceptible to relaxation (due to the associated soft metal gaskets),. PNL recomends these be checked 100% at the same frequency. (One conse'quence of the loss of air start valve capscrew preload may be loss of cylinder compression; another will be " torching" of the passage permitted by a
" loose" . valve, with consequential irreparable damage to the head, and with potential risk to operating personnel from hign velocity, unnoticeable hot gases.)
5.1.2.14 Jacket Water Pumo
' TUGC0 provides no maintenance plan for the jacket water pumps. PML recommends disassembly / examination at the first refueling outage.
The jacket water pumps on both Train A and B enginer exhibited damage of various forms. Shaft galling, worn wearing rings, or a warped backing plate can cause reduction in pump capacity and pump life, both of which are detrimental to engine reliability and operability.
5.19
TUGC0 was not able to identify the cause of these damages but did replace all damaged parts. Based on the coincident damage exoerienced on the pumps on each engine, this event is being considered specific to the CPSES Unit i engines. The damage could have been sustained at the factory during testing and/or during startup due to incorrect system commissioning.
PNL Recnemendations Because of the critical nature of this pump and the history of the above problems, PNL recommends that the pumps be disassembled and inspected and repaired as necessary at the first refueling outage.
5.1.2.15 Lube Oil Checks TUGC0 proposes a monthly surveillance check at the inlet to the filter.
PftL recommends more definitive checks for water and other contaminants after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />' operation or monthly, dichever is first.
Lube oil checks serve two main functions:
e They reveal any water in the oil, indicative of cracks in water-bounded components or leakage past lower linar seals. Such water can lead to lubrication failures, with potential major damage.
e They reveal abnormal wear of bearings and related engine parts.
it is important to collect and analyze samples with sufficient frequency that adverse conditions are detected early enough to avoid either engine damage or engine outage (and possibly consequential reactor snutdown). PNL basically agrees with TUGCO's proposal with the following modification.
pNL Recommendations
, pML recommends the following pattern:
l e
Check for water contamination after preoperational testing, and then monthly or after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of operation, whichever comes first; col-lect the sample from the bottom of the sump tank, preferably about
~
4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after engine shutdown, at the time of the eng. e roll-over.
e Check for chemical and particulate contamination and imbalance near the close of preoperational testing, and then monthly or after 5.20 l
l
,-4y. - . . , - - _ _ - . _ . - , -- - .,-
l l
24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of operation, whichever comes first; collect the sample (before the filter) while the engine is running, immediately prior to shutdown.
e C1eck differential pressure across all filters and strainers hourly during engine operation.
, 5.2 OPERATIONAL SURVEILLANCE PLAN 5.2.1 Elements and Rationale Operational surveillance is necessary to ensure safe and efficient operation of the diesel engine. By monitoring and recording various engine parameters, trends in oegradation may be noted, thus allowing preventive maintenance. In addition, trend monitoring permits engine shutdown prior to major engine failure. A listing of recommended parameters and frequency of surveillance is presented in Table 5.3.
5.2.2 PNL Evaluation NRC's guidance was for continuous monitoring and' hourly recording of exhaust temperature, including the pre-turbine temperatures. TUGC0 has proposed recording of exhaust temperatures on the half hour, without mention of pre-turbine temperatures.
pML's consultants deem it very desirable to monitor .the turbine inlet temperature for these reasons:
- Monitoring would avoid the possibility of such temperatures exceeding tne limits set by the turbocharger manufacturer.
e It is possible for the " average" inlet pre-tureine temperature to
- exceed the " average" temperature measured at the individual cylinder outlet (the latter reflects a time-averaged comoination' of true exhaust temperature and a much lesser quantity of cooler " scavenging air" that occurs during valve overlap in the exhaust / intake strokes ) . This. higher actual turbine inlet temperature results from three possible conditions: 1) The pulse of hot exhaust and the subsequent, lesser pulse of cool air may not nix, even though two 5.21
t TABLE 5.3.
Diesel Engine Operating Surveillance Parametert and Frequency TUGC0-- PNL Component NRC Guidance proposal Recommendations Luoe 011 Inlet Pressure Monitor continuously. Log every Log every to Engine recera hourly 30 minutes 60 minutes furoocharger 011 Pressure Puso Fuel 011 Filter / Strainer ap Luce 011 Filter / Strainer aP Jacket Water Pressure Crantcase Vacuus Engine Speed Stact Temperature (R8. LS)
Lune 011 Temperatu.e Jacket Wate Temperature
(!n. Out)
Luse 011 Sumo Level
- Room Temperature Engine Cylinder Temperature (all)
Ulomett Load Engine Hourmeter Eanaust Temperature Inlet Monttor continuously. Not to Turco (R8 L%) record nourly Proposed 4
Fuel 011 "ransfer Pump Stratner aP Log every Log every 30 minutes 60 minutes unless pumo-1s al.'o/
ouolexed and alarmed Starting Air Pretsure --
Log every (28. LSI Chect nourly 20 minutes Fuel 011 Day Tana Level --
Log every Chect nourly 30 minutes Manifold Air Pressure Monitor continuously Net (RS. LS) Log every record hourly Proposed 60 minutes Mantfold Air Temperature ---
Not-(RS. L1) Log every Proposed 60 minutes Visual Inspection for Leats, etc. Not Chect hourly Proposed 5.22 e
cylinders are involv2d with each manifold; 2) exothermic chemical reactions tend to continue after the cylinder exhausts, even with g, roper firing timing; and 3) any inappropriate timing of fuei injection can lead to continuing flame propagation during exhaust.
e Plots of pre-turbine temperatures for TOI OSRV-16 engines show that, at full load and overload (i.e., the TOI rating of 7000 and 7700 kW, respectively), the temperatures of even properly-timed engines can approach 1200*F (the reported upper limit allowed by the turbocharger manufacturer),
o Vanes have been found damaged and missing on the CPSES turbochargers; the same finding has been noted elsewhere on similar engines in nuclear service. Because the mechanism of the vanes' damage and af sappearances has not e b' en identified with certainty, it is impcrtant to avoid influences toward thermally induced failures.
PNL Recomendations Table 5.3 lists those parameters that TUGC0 plans to use to monitor engine perfo rmance.
PNL and NRC recomend the continuous monitoring and/or hourly recording of turbocharger inlet exhaust temperatures, manifold air pressure, and mantfold air temperature. The TUGC0 program to log the vicious parameters at 30-minute intervals is acceptable but considered in excess of normal 1-hour intervals.
5.3 STANOBY SURVEILLANCE PLAN 5.3.1 Elements and Rationale
, Standby surveillance is important to ensure the reliability of the diesel engj nes . The parameters monitored on a " secured" engine show that it is pre-pared for rapid startup and load acceptance. The tc factors that contribute most to this are engine temperature and lubrication. Thus , by keeping the engine warm and all oil passages pressurized, the time lag associated with load acceptance is minimized.
In addition, a ready supply of quality compressed air is required for starting the engine. Patterns of standby surveillance of the engine are shown in Table 5.a.
5.23 m . . . _ _- _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ . . .
-(). TABLE 5.4 Diesel Engine Standby Surveillance Parameters and Frequency NRC TUGC0 PNL Component Guidance Proposal Recommendatiens Starting Air Pressure ~
--- Every 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> Visual check every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />; log every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Lube 011 Temperature (In, Out) ---
Jacket Water Temperature ---
Fuel 011 Day Tank Level ---
Room Temperature ---
Test Annunciators --- '
Every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />; log -
every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Check Alarm Clear, --- Oaily Daily i Check Operation of Comp. ---
i Air Traps
() Operation of Fuel Rack ---
Governor Oil Level ---
Inspect for Leaks ---
Air Butterfly Valve and- ---
Weekly Weekly Cylinder Check Internals of Block --- Monthly At eacn refueling and Base for Leaks outage Keepwarm Oil Filter aP Daily ---
Weekly Test Jacket Water for pH, Con. ---
At each refueling After adding make ductivity, Corrosion Innibitor outage up water, or monthly Cylinder Compression / Peak ---
At eacn refueling At each fefueling Pressure outage outage Air Start Distributor Filter --- Monthly Monthly Air Start Admission --- Every 3 months Every 3 mentns Valve Strainer i
t i
5.24 i
I y 4 y w- + e-r,-v- p 4m-- -- .,
e D 5.3.2 PNL Evaluation _
g NRC's guidelines for standby surveillance recommend a daily check of lube oil filter differential pressure. The TUGC0 proposal covers several parameters to be monitored every 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, but does not mention the lube oil filter. It is felt that the 4-hour monitoring cycle is more than necessary for a standby engine; the parameters may be checked visually every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and recorded
. daily. Two points regarding the lube oil filter are important:
Entrained water will tend to plug some filter media (or weaken others), and so would gradually change pressure drops.
e The continuous keep-warm flow through the filters will (purposefully) continually " polish" the oil, with gradual buildup of contaminants in the media; the material scavenged out thereby itself helps filter even finer particles as time continues. '
Thus, it remains valid to monitor oil filter pressure drops during standby.
However, the difference between a daily check (per NRC guidance) and a weekly check is not deemed significant; the latter is considered acceptable.
PNL Recommend 1tions g
PNL reconsnends a weekly check of all oil filter pressure drops during standby.
The hourly check during sustained engine operation remains important.
Otherwise, the TUGC0 proposal is acceptable, with certain additions and clarifications recommenced above ard shown on Table 5.4 A i
5.4 PNL CONCLUSIONS PNL concludes that the TUGCO-proposed M/S activities require modification to provide adequate assurance of engine reliability / operability. The recomended modifications, with supporting rationale, are delineated in the preceding subsections (5.1, 5.2, 5.3). With those modifications, the TUGCO-proposed M/S program is considered acceptable through the first refueling cycle.
As the Owners' Group Program Plan and related M/S activities become fully developed and accepted by NRC, it may be appropriate for TUGC0 to modify their plan still further, 5.25
9 9 9
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1_ _ ___
6.0 ENGINE TESTING h This section reviews and evaluates the engine testing program identified by TUGCO.
Included are post-inspection tests prescribed by the information provided in an NRC letter (Youngblood August 2,1984), and routine / periodic ;
testing in accordance with NRC Regulatory Guide 1.108, Revision 1. This section also provides an evaluation of data concerning onsite starts of the CPSES Unit i engines prior to the disassembly and inspections.
l 6.1 TUGC0 REPORTED POST-INSPECTION TESTING TUGC0 reports they have conducted engine break-in runs, calibration runs, and preoperational tests following reassembly of the Train A and Train 8 l engines. The detailed preoperational tests were done in conformance with NRC Regulatory Guide 1.108, Revision 1, and as specified in the applicable sections of the NRC letter (Youngblood August 2,1984). Detailed results of the post-inspection tests are not yet available; however, TUGC0 did report certain failures / observations and actions taken to resolve them. These are listed in-Table 6.1.
llh TABLE 6.1. Preoperational Test Results Recorted Failures / Observations Planned TUGC0 Resolution -
Fuel injection pump failure on Train A led to manual engine shutdown. Effort initiated to determine cause; initial findings are that top bolts were improperly torqued; all pumps were checked for proper torque.
The phase metering potential for the Determined to be caused by failed Train A engine was lost for about solder joints on two of four screw-in 1 minute. type fuse holders; all such screw-in holders were replaced with new car-
. tridge-type holders on both enginet.
Pneumatic tubing associated with Train A All pneumatic tubing on both Train A engine protective trip function was and B~ engines will be replaced with was found to have corrosion, stainless steel tubing prior to fuel loading.
l 6.1 e
i TUGC0 also reports that, since engine assembly in Spring 1984, the Train A engine has undergone 45 starts anc has accumulated 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> of operation (load not stated). The Train B engine has undergone 54 starts and 84 additional hours of operation (load not stated).
TUGC0 reported that all testing on the diesel generators was done at or below 5.8 MW, except for approximately one-half hour of load rejection testing at 7 MW. TUGC0 reports that tetting below 5.98 MW provides assurance that the cylinder BMEP will be below 185 psig. ,
6.1.1 pNL Evaluation PNL believes TUGCO's plans regarding post-inspection testing should include two elements:
- 1. The engine manufacturer's reconenended post-reassembly tests.
- 2. The testing specified in NRC Regulatory Guide 1.108, Revision 1, as modified by NRC post-inspection testing requirements specified in Youngolood ( August 5,1984).
The modifications mentioned in Item 2 above include the following tests:
O e Ten modified starts to 40 ioad. ( A mod 4 f 4ed start is a start including turbocharger prelube and a 3- to 5-minute loading to the specified load and run for a minimum of 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.)
e Two fast starts to a load greater than or equal to the maximum emergency loads the engine will experience but not greater than a load corresponding to 185 psig BMEP. (A fast start simulates an ESF signal with the engine in ready-standby status.)
e One 24-hour run at a load greater than or equal to the maximum emergency loads the engine will experience but not greater than a load corresponding to 185 psig BMEP.
TUGC0 did not report on tests to the manufacturer's recommendations (Item 1 above). However, PNL assumes that appropriate engine manufacturer's required testing was accomplished and that the TUGC0 post-reassembly test report will provide these results.
6.2
With respect to the reported failures or observations (corrosion) by TUGCO, PNL believes these are routine and that the reported actions are appro-priate. PNL assumes that the fuel injection pumps for both engines (not just Train A) were checked for proper torque. This should be verified by TUGCO.
TUGC0 did not report whether all post-assembly starts for both engines were successful. This will be confirmed by TUGC0 in a detailed supplement to their earlier submittal (George August 15, 1984).
PNL has learned that half-hour load rejection tests requiring engine operation at 7 MW will not be repeated. These tests required cylinder pres-suces well in excess of the 185 psig BMEP currently evaluated as acceptable for these engines, pending completion of the Owners' Group Program. On this same topic, PNL finds that the TUGC0 analysis showing that the 185-ps.ig BMEP limi-tation corresponds to 5.98 kW did not consider the generator efficiency. Using an estimated efficiency of 0.96, PNL calculates that the 185-psig BMEP limit corresponds to 5.74 MW. Engine testing should be limited to this value.
6.1.2 PNL Conclusions Based on its review, PNL concludes that TUGCO's post-inspection testing on the Train A and B engines is compatible with NRC requirements. In addition, h
PNL has learned that TUGC0 has informed NRC that the manufacturer's recor:rnended testing has also been performed.
PNL concludes that TUGC0 has taken apcropriate action regarding tne reported failure and observations (corrosion) occurring during post-reassembly testing. PNL also concludes that the final disposition of these items should be supplied in the TUGC0 submittal to NRC describing post-inspection test results. PNL concludes that no future testing above cylinder pressures of 185 psig BMEP (corresponding to a load limit of 5.74 MW) should be performed without prior NRC approval.
In summary, PNL concludes that post-inspection testing of both Unit i engines has been satisfactorily completed. This conclusion is conditional upon the receipt and satisfactory aeview of the TUGC0 post-inspection report, con-firmation regarding testing per TDI specifications, and limits on future test loads as stated above.
6.3
() 6.2 REVIEW AND EVALUATION OF ENGINE STARTS PNL has reviewed the data sheets documenting the onsite starts of CPSES Unit i diesel engines that were run prior to engine disassemoly and inspec-tion. The Train A engine was started 67 times between September 29, 1982, and March 29,1983. The Train 8 engine was started 83 times between September 16, 1982, and May 31, 1983.
During these tests the Train A engine experienced eight abnormal engine shutdowns. Two of these shutdowns were attributed to operator error, two were attributed to errors in the procedures, two were a result of miscalibration of the high vibration ; rip, and two were caused by a field ground relay trip (the
. field ground relay trip would be overridden in an energency).
The Train B engine experienced nine abnormal shutdowns during these tests.
Two that TUGC0 nas classified as " unsatisfactory engine response" include 1) a low oil pressure trip caused by an incorrectly installed foot valve in the auxiliary luce oil pump and 2) a short in the OC. power supply caused by a blown-out indicator light. Of the remaining seven, two were a result of an incorrectly calibrated high vibration trip, and five shutdowns were attributed
{} to operator error.
Diese data fully corroborate Section 3.1 of TUGCO's August 15, 1984, sub-mittal, which identifies only two instances of unsatisfactory engine res ponse. In both instances, PNL feels the cause of the unsatisfactory
! performance has been identified and appropriate corrective action has been taken.
6.4 '
l 1
i 7.0 OVERALL CONCLUSIONS h 7.1 GENERAL CONCLUSION In general, PNL and its consultants conclude that the two TDI OSRV-16-4 diesel engines at the Comanche Peak Steam Electric Station Unit I will have the needed operability and reliability to fulfill their intended emergency power 6
function, at least to the time of the first reactor refueling outage.
This conclusion is predicated upon the known results of the completed
, extended operational tests and subsequent inspections. It also reflects PNL's current knowledge and evaluation of the ongoing Owners' Group investigation on specific, generic component issues. It is also contingent upon satisfactory completion and documentation of all actions recomended in this. TER and identi-fied in the Aucust 15, 1984, submittal from TUGC0 to NRC. These actions are summarized in Section 7.3. The PNL conclusions pertaining to the operability of the Train A and 8 engines are contingent upon TUGCO's timely implementation
. of all OG recommendations and plant-specific items that may result from the CPSES-specific OR/QR investigations.
O 7.2 LONG-TERM APPLICABILITY In Section 1.2 of this TER, PNL expressed its opinion and rationale that it cannot responsibly reach conclusions on the operability anu relia:ility of the Comanche Peak Train A and Train B standby engines beyond the first refuel-ing outage. Hence, throughout this report, PNL has expressed its conclusions in such terms as "until the first reactor refueling outage." This constraint has be1tn predicated upon all evidence available to PNL, including preliminary elements of the OGPP and the TUGC0 evaluations as applicable to these specific engines. When these analyses are completed and appropriately implemented, and when operational results on these engines (under enhanced surveillance and maintenance) and on others in the general population of equivaient TDI engines are accumulated, it may then be possible to draw unconstrained, long-term conclusions.
1 l
7.1
'O tt is ao aa iateat aa ever 'a e aress'as ta's coastra'at to 'mais any inheren+. unreliaoility or inoperability of these engines, either specifi.
.cally at CPSES or in general nuclear standby service.
7.3 LICENSING CONSIDERATIONS The conclusion stated in Section 7.1 reflects PNL's careful evaluation of all TUGC0 and Owners' Group submittals. Specific considerations have been
- addressed in Sections 3.0 through 6.0 of this TER and reference should be made thereto for PNL's component-specific conclusions and recommendations. PNL assumes that TUGC0 will agree to modifications or additions to their August 15 submittal that appear in these sections.
Certain considerations warrant emphasis. They relate to TUGC0 commitments and to recommendations made by PNL. The conclusion by PNL regarding the Train A and Train 8 operability and reliability to serve as nuclear standby emergency power supplies throughout the first refueling cycle is predicated on an understanding that a technical review of all TUGC0 submittals concerning open items described below will not raise unanticipated problems. The open O items are Presented in four catesor4es: 1) seaeraii 2) oPea items spec 4f4caii,
! identified by TUGC0 in Section 10.0 of the August 15, 1984, submittal; 3) open items mentioned by TUGC0 in the August 15, 1984, submittal'but not addressed in Section 10.0 of that submittal; and 4) concerns raised by PNL to be addressed by TUGC0 prior to PNL concluding that the engines are ready for nuclear service.
7.3.1 General Considerations The following items relate to TUGCO's conformance with the ongoing Owners' l Group Program and certain significant NRC and PNL requirements and recommenda-tions.' They are:
j e PNL understands that TUGC0 will implement all relevant Owners' Group recommendations in a timely manner.
I
~
O 7.2 .
l e Should any remaining inspections, further testing, OR/OR findings at CPSES, or functional occurrences at other plants reveal adverse g
l t
conditions or results not currently expected, modifications of the
- PNL conclusions may be warrcnted. ;
l e PNL assumes that TUGC0 will resubmit to NRC a revised surveillance and maintenance plan incorporating changes and additions such as those identified in Section 5.0 of this report.
e PNL understands that engine testing and emergency service require-ments TUGC0 now foresees for the CPSES will not exceed the engine load corresponding to a BMEP of 185 psig (5740 kW).
7.3.2 TUGC0 Ooen Items Identified and Adaressed The items identified below are listed in George (August 15, 1984, Section 10.0) as Open Items for CPSES Unit 1. TUGC0 has agreed to close out and document these items prior to fuel loading.
7.3.2.1 Crankshaft Ooen Itens e crankshaft main journal oil hole inspection for both CPSES Unit 1, engines h
e crankshaft torsiograph test for one engine e evaluation by the Owners' Group of the TDI recommendation for running of crankshafts for 15 minutes at 150 rpm following each major over-haul, in light of the Owners' Group recommendation to run at 450 rpm at all times.
7.3.2.2 Cylinder Block Ooen Items e TUGC0 review of an additional Phase I supplementary report by the 4
Owners' Group on cylinder block strain gauge testing on the Train A engine at CPSES Unit i e TUGC0 review of an additional Phase I supplementary report by the Owners' Group on cylinder block metallurgical testing at all sites e establishment of CPSES Unit I cylinder block top eddy-current inspection intervals based on the above.
7.3 h
2 k-- - =^- ea----- m ~-_-__,a- -
t q 7.3.2.3 Fuel Oil Injection Tubing Open Items kJ e Installation of shrouded SAE-1010 high pressure fuel oil injection tubing for both CPSES Unit 1 engines e eddy-current inspection of newly installed tubing for flaws e visual inspection of newly installed tubing for leaks during engine operation e modification of tubing affected by the 10 CFR Part 21 report of September 21, 1983.
7.3.2.4 Connecting Rod Ooen items e TUGCO review of an additional Phase'l supplementary report by the Owners' Group on connecting rod strain gauge testing at another site a evaluation of CPSES Unit I connecting rod inspection requirements based on the above.
7.3.2.5 Turbocharger Ooen Items e Modification of the CPSES Unit 1 turbocharger lube oil drip systems .
O to ta c co aa t'oas sa c** by Tot ro"o~'a9 ta to cra aart 2t report by the Owners' Group on design review of turbocharger vanes and capscrews.
7.3.2.6 Additional Ooen Items e Replacement of 16 remaining original exhaust manifold bolts on Train 8 with new TOI socket head types e replacement of' pneumatic tubing for engine protective functions with stainless steel tubing ,
e TUGC0 review of the CPSES Unit 1 Phase 2 report by the Ownars' Group e re-evaluation by the Owners' Group of the recommendation for destructive testing of push rods on a sample basis e detailed evaluation of C .,ES Unit I diesel generator preoperational testing
- 7.4
e recording of CPSES Unit I diesel generator pre-turbine exhaust h temperature relative to the TDI recomended maximum as specified by NRC e submittal of proposed technical specifications to limit monthly and 18-month CPSES Unit i diesel generator surveillance testing to 185 psig BMEP.
7.3.3 Other TUGC0 Identified Open Items PNL has identified additional open items mentioned by TUGC0 in the i August 15, 1984, submittal but not addressed in Section 10.0 of that sub-mittal. PNL believes that these items need to be addressed prior to qualifying the Unit 1 TDI diesel engines for nuclear service:
o results of material check on air start valve capscrews (p.16) and rocker arm capscrews (p. 15 of the TUGC0 August 15, 1984, document) e results of formal esaluation of the indication on No. 3 main bearing saddle, Train A. .This should include the determination of the "large factor of safety against propagation" and, as appropriate, the basis for the OG's " conditional release to permit reassembly and -
preoperational testing" (p. 34) e results of the TUGC0 investigation of the fuel injection pump failure on Train A engine (p. 53).
7.3.4 Ooen Items Raised by the PNL Review In Section 3.0 of this Technical Evaluation Report, PNL has raised a number of issues to be ac4ressed and documented by TUGCO. In PNL's view, these concerns should be resolved ,'aior to concluding that the TDI engines are suitable for nuclear service:
e engine base and bearing cap (Section 3.2.1 of this TER), Train A -
satisfactory resolution of the indication on bearing saddle No. 3, still under formal evaluation (as referenced previously above), with either a disposition as being shown to be of no further concern, or -
rationale for operation with enhanced monitoring (with details) 7.5 L
I
e cylinder block .(Section 3.2.2), .both Trains A and B - completion of
[ ])'
acceptable OG analyses and reports on indications that are fonnally under OG review, and submission of detajls on an acceptable plan of monitoring and evaluation based on these results e crankshaft (Section 3.2.3), both-Trains A and B - submission of evaluation of hot and cold shaft deflection tests e connecting rods (Section 3.2.4 and Section 5.1.2.4), both Trains A and B - submission of a satisfactory plan for enhanced monitoring and inspection of cross-joint bolting and/or rod box surfaces and/or rack teeth e connecting rods (Section 3.2.4), both Trains A and B - submission of a letter to NRC confirming information provided by telephone' regard-ing removal of burrs and sharp edges on bolt holes, TDI factory
" blueing in" of rod racks, and final preparation of rod rack surfaces e cylinder liners (Section 3.2.7), both Trains A and B - confirmation of satisfactory material per analyses being conducted by FaAA
(]) e starting air distributor (Section 4.2.2.2), Train B - completion of a satisfactory inspection e surveillance and maintenance program (Section 5.0) - submission of a revised program with appropriate modifications to accannodate PNL comments.
m 7.6
I L . .. .
l PNL-5234
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. ATTACHMENT 5 l
l TDI DSRV-16 DIESEL GENERATOR ENGINE RATINGS
- GRAND GULF CATAWBA COMANCHE HARRIS RATING (MP&L) (DUKE) PEAK (TUGC) (CP&L)
Displacement 76266 in3 76266 in3 76266 in3 76266 in3 KW(design) 7000 7000 7000 6500 1
BMEP** 225 psi 225 psi 225 psi 209 psi BHP *** 9770 0450 9770 @450 9783 0450 9074 0450 RPM RPM RPM RPM l 2 HOUR 7700 (110%) 7700 (110%) 7700 (110%) 7150 (110%)
RATING (KW)
MAX. LOAD 3495(Div.1) 5714 A - 7019 ****
(safe 3703(Div.2) B - 6686 A - 5524 shutdown) B - 5571 (KW)
[ (safety injection)
(LOCA) KW 4654(Div.1) 5256 A - 6355 ****
3712(Div.2) B - 6355 A - 5592 (Recirc.) B - 5598 A - 6370 B - 6370 l
- Information provided by Diesel Generator Owners' Group
- Brake mean effective pressure at maximum load
- Brake horsepower