ML20127B927
Text
- _ -
PNL-5201 Review and Evaluation of Transamerica Delaval, Inc.,
Diesel Engine Reliability and Operability - Grand Gulf Nuclear Station Unit 1 July 1984 l
Prepared for the U.S. Nuclear Regulatory Commission under Contract DE-AC06. 76RLO 1830 NRC FIN B2963 I
Pacific Northwest Laboratory Operated for the U.S. Department of Energy by Battelle Memorial Institute a
l 7
OBattelle i
'f
&448$1pS73XR
l l
l DISCLAIMER 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 legal liability or responsibility for the accuracy, com-pleteness, or usefulness of any information, apparatus, product, or process disclosed,or represents that its use would not infringe privately owned rights.
Reference herein to any specific commercial product, process, or service by trade name, trademark, manufac'urer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
PACIFIC NORTHWEST LABORATORY operated by BATTELLE for the UNITED STATES DEPARTMENT OF ENERGY under Contract DE-AC06-76RLO 1830 er l
l 1
PNL-5201 REVIEW AND EVALUATION OF TRANSAMERICA DELAVAL, INC.,
DIESEL ENGINE RELIABILITY AND OPERABILITY - GRAND GULF NUCLEAR STATION UNIT 1 l
July 19B4 Prepared for Division of Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission under Contract DE-AC06-76RL01830 i
NRC FIN B2963 l
Project
Title:
Assessment of Diesel Engine Reliability / Operability NRC Lead Engineer:
C. H. Berlinger Pacific Northwest, Laboratory Richland, Washington 99352 9
_..s.._.
-si.
PACIFIC NORTHWEST LABORATORY PROJECT APPROVALS ek a
Date
%'w H $0, f $
W. W. Laity, Project Manager [/
Pacific Northwest Laboratory
^
Date l ' LO" % f
-= -
W. D. Richmond, Chairman Senior Review Panel Pacific Northwest Laboratory 4
.4 1
=
i 11
. ~.. -.,,,
CONTENTS
1.0 INTRODUCTION
1
2.0 BACKGROUND
3 2.1 OWNERS' GROUP PROGRAM PLAN......................................
3 2.2 GRAND GULF NUCLEAR STATI0N......................................
4 e
3.0 EVALUATION OF MP&L DIVISION I ENGINE DISASSEMBLY AND INSPECTION......
6 3.1 GENERIC PR0BLEMS................................................
7 3.2 PLANT-SPECIFIC PR0BLEMS.........................................
30 4.0 ANALYSIS OF THE REQUIREMENT FOR DIVISION II ENGINE INSPECTION........
34 4.1 DIVISION I ENGINE INSPECTION RESULTS............................
34 4.1.1 PNL Evaluation...........................................
3a 4.1.2 PNL Conclusions..............................
34 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 TESTI NG................................
37 5.1 PNL EVALUATION..................................................
37 5.2 PNL CONCLUSIONS.................................................
37 6.0 REVIEW 0F THE PROPOSED AUGMENTED MAINTENANCE / SURVEILLANCE PROGRAM....
39 6.1 PNL EVALUATION..................................................
39 6.1.1 Cylinder Heads...........................................
41 6.1.2 Connecting Rods..........................................
41 6.1.3 Lu b e O i l Ch e c k s..........................................
41 6.1.4 Studs / Fixtures...........................................
42 v
e
~_
6.1.5 Pu s h Ro ds, Ca ms, Et c.....................................
42 6.1.6 Addi tio nal Su rvei l l a nce..................................
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 LIMITATIONS.........................................
46 7.4 REVISED SURVEILLANCE / MAINTENANCE PR0 GRAM........................
46 I
1 m
vi
REVIEW AND EVALUATION OF TRANSAMERICA DELAVAL, INC., DIESEL $NGINE 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 Station (GGNS) Unit 1 and in response to an NRC Order dated May 22, 1984, Mississippi Power & Light Company (MP&L) submitted a report on July 5,1984, addressing three areas:
a description of the June 1984 disassembly and inspection of the e
Division I diesel generator the post-inspection engine test program e
e proposed enhancements to the MP&L maintenance and surveillance program.
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. These 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 background 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 MP&L report on the comparability of the Division I and Division II engines. Sections 5 and 6 document PNL's review / evaluation of MP&L's post-inspection engine tests and the 1
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 GGNS.
This TER was prepared by the following PNL staff and consultants:
e D. A. Dingee, PNL project staff e
A. J. Henriksen, diesel consultant to PNL J. E. Horner, representing Seaworthy Systems, Inc., diesel consultants to e
PNL P. J. Louzecky, Engineered Applications Corporation, diesel consultant to e
PNL.
Others whose contributions were considered in formulating the conclusions include PNL Assesment of Diesel Engine Reliability / Operability Project Team members 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).
9 9
w 2
g.,
l t
l l
2.0 BACKGROUND
2.1 OWNERS' GROUP PROGRAM PLAN Thirteen nuclear utilities that own diesel generators manufactured by Transamerica Delaval, Inc. (TDI), have established an Owners' Group to address questions raised by a major failure in one TDI diesel (at the Shoreham Nuclear Power Station in August 1983), and other problems in TDI diesels reported in i
the nuclear and non-nuclear industry. On March 2,1984, the Owners ' Group submitted a plan to the U.S. Nuclear Regulatory Commission (NRC) outlining a comprehensive program including 1) an in-depth assessment of 16 known engine 4
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:
The engine should have AE pistons or complete " lead-engine" tests as e
described in Section 2.3.2 of PNL-5161.
The diesel generator should not be required to carry a load in excess of that cor.v ponding to engine Brake Mean Effective Pressure (BMEP) e 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 e
Section 2.3.2 of PNL-5161.
e The engines should receive enhanced surveillance and maintenance.
1 3
a S
o
, +
n
-.y,..
,,--e.
n-v.
,-p,
-.s,
2.2 GRAND GULF NUCLEAR STATION An MP&L submittal to NRC, dated February 20, 1984, provided a review of the results of their program of inspection, upgrading, testing and maintenance. The PNL review of this document was provided to NRC in a letter dated March 30, 1984 A number of concerns were identified by PNL, namely:
- The MP&L report did not provide sufficient information to convince the reviewers that the AE pistons were suitable for GGNS licensir.g.
The evidence was insufficient to conclude that the cylinder heads e
would perform reliably.
The connecting rod bearings were not demonstrated to be suitable for e
operation at GGNS.
The push rods were not adequately tested.
e Data concerning crankshaft deflections and main bearing wear were e
needed to confirm the adequacy of the crankshaft.
e The high-pressure fuel line needed to be examined to assure the reviewers that the new lines installed at GGNS are not defective.
MP&L did not adequately consider the possibility of cracks in the e
cylinder block.
Additional information was needed to confirm that the engine base e
would not crack.
e MP&L did not address head stud problems noted by the Owners' Group.
The issues on rocker arm capscrews were not closed out per the e
Owners' Group recommendations, The PNL reviewers needed more information from MP&L on turbocharger e
mounting.
The evidence provided by MP&L on the connecting rods was insufficient e
to conclude that they would be adequate.
e 4
t
MP&L did not address the potential for wrist pin bushing failures; e
PNL noted that cracks had been observed in wrist pin bushings at the Shoreham Nuclear Power Station.
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 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 i' sued an Order dated May 22, 1984, requiring s
disassembly 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 engine for the first reactor fuel cycle.
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 DG, and addressed post-inspection testing and a proposed augmented maintenance and surveillance program aimed at assuring the future satisfactory performance of both engines. This submittal was the topic of discussion at a meeting held July 13, 1984, among representatives of MP&L, NRC, and PNL.
5 r
m
~
3.0 EVALUATION OF MP&L DIVISION I ENGINE DISASSEMBLY AND INSPECTION In compliance with the NRC Order of May 22, 1984, MP&L disassembled the Division I TDI engine and inspected all critical compor.ents. These components included those that are being addressed as part of the Owners' Group Phase I Program regarding known generic problem areas:
cylinder heads, 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 inspecticn 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 cuver 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.
6
3.1 GENERIC PROBLEMS s
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 installations, 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 piston skirt, labeled AE, in either nuclear or non-nuclear installations. Kodiak 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 TDI 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 ' Group 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 r:0t propagate 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. Subse-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 by liquid penetrant and no rejectable indications were observed. However, the piston skirt-to-crown surface on all skirts and crowns showed slight 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
}-
experience with the Kodiak and R-5 engines, PNL concludes that the piston 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").
a e
e i
i i
4 a
4 J
8 y
d-w-+-
F g
we-+-
tn-yg-g-ewy%,--p eg ww,p-w-y-yv++wy -
9yq--2,-
9v e-gqi sp@P-p3-p u gp e e g
= - -
- yMt
Component: Connecting Rod Bearing Shell Part No. 02-340-04-AG 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 conrod bearing shells.
Provided the shells are dimensionally correct and otherwise conform to specifications as recommended by the FaAA report, FaAA has concluded that the bearings are suitable for the service intended.
MP&L Status In January / February 1984 all conrod 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 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.
M 9
9
/
,,r-r-
Component: Rocker Arm Capscrew Part No. 02-390-01-0G 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 the failure at Shoreham to undertorquing.
MP&L 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 4
acceptable service.
4 10 4
.y-
~
Component: Air Start Valve Capscrews 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 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.
MP&L Status Capscrews on both Division I and II DGs have been modified by shortening the 3-inch capscrews by 1/4 inch. Proper torque values were confirmed after reass embly.
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.
11 4
r e
r v
v
~
i l
Component:
Push Rods Part No. 02-390-06-AB s
i.
Owners' Group Report:
FaAA 84-3-17 l
Brief History of Failures j
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 consisted of a tubular steel body with a carbon steel ball fillet welded f
to each end. This design proved to be very prone to cracking at the weld.
In j
all,15 of 16 rods on the GGNS Division I engine and 13 of 16 rods on the j
Division II engine were found to be cracked. All push rods on both Division I 1
and Division II DGs have been replaced by a new design consisting of a tubular j
steel body with a steel cylinder friction-welded to each end.
No failures are reported on this design.
1 Owners' Group Status Failure Analysis Associates has a performed stress analysis as well as 7
cycle wear test to 10 cycles on a sample of the friction-welded push rod at conditic s simulating full engine nameplate loading. No sign of abnormal wear or deterioration of the welded joints was observed.
t 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 j
were observed.
PNL Conclusions After reviewing the FaAA report and inspection data and noting the GGNS i
replacements, PNL concludes that the push rods incorporating the friction weld.
design are' acceptable for the first refueling cycle.
l 12 i*
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 is'olated failures have been reported in the non-nuclear field. The cause has not been reported.
1 Owners' Group Status Stone & Webster Engineering Corporation has analyzed both the old design studs and the new necked down studs developed by TDI to minimize cylinder block cracking, and has concluded that both stud designs are adequate for the service intended, provided proper stud preload is applied.
i 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 bottom threads. On the engine'left bank cyli1 der 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 confirwed 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 MP&L, PNL concludes that the cylinder head studs are acceptable for the first refueling cycle.
I 13
Compo.nent: High-Pressure Fuel Tubing Part No.:
03-365C Owners' Group Report:
Stone & Webster, April 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.
m 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 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 than the high-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 high-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 concludes that the HP fuel tubing is acceptable for the first refueling cycle.
14
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 rated 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.
MP&L Statu1_
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 with no indications noted. Minor scratches were noted on several crank journals. Also, on crank journal No. 4 a slight metal buildup (rodbearing replaced) was noted; it was removed and the journal polished. Hot and cold crankshaft deflections have been measured and documented and reported to be within TDI and Owners' Group specifications.
15
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").
16 l
,- w
Component: Turbochargers Part No.:
Elliott 90G Owners' Group Report: Fa AA-84-5-7 Brief History of Failures Reports of turbocharger thrust bearing problems are limited to the nuclear industry. To date, thrust be& ring 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 problems 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 " fast" starts (i.e., automatic starts for which no prelubrication is provided to the thrust bearing). Several 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. 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 right-bank turbocharger.
It was assumed that the capscrew heads 17
had passed through the turbine. On the left-bank turbocharger, one nozzle ring 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-ch arger. 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 metallurgically examined and the failure mechanism determined to be intergranular stress corrosion cracking, believed to have been initiated by sulfurous 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, where the thrust bearings, although still serviceable, were replaced.
Noz21e 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' Group, 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:
According to Failure Analysis Associates, as confirmed in a telephone e
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 failure.
18
On the basis of operating experience at GGNS over a 2-year period, e
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, t? o indicating t
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 /> of operation have occurred without incidents attributable to misalignment or vibration. PNL concludes that MP&L 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 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.
t
+
e 9
19 l
l l
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 observ'ed. 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 ' Group 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 18, 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 disappear 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. TDI 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 the 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 with 1-7/8-inch bolts and a later des'ign in which the rod boxes are equipped with a 1-1/2-inch bolts. Stress analysis, including finite element, 20 e
w - -
-y
l 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 belts 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 recommended measurements described above.
The status of the fatigue cracking in the rod boxes is as follows. Both Division I and 11 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:
Serrated joint teeth surfaces were found to have minor fretting on all conrod boxes. At NRC's request, the serrated teeth were dressed via stoning and the contact surface verified by " blueing" as per TDI specifications.
Conrod 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.
Conrod bolt inspection revealed that approximately 50% of the bolts
'~
had minor galling, which was judged to be maintenance-related. All bolts were replaced with fully inspected new bolts. When bolts were installed, they were properly lubricated as per instructions. Proper preload was ascertained by ultrasonic methods.
21
I All conrod dimensions were checked and found to be within specified I
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 PNL concurs with the MP&L resolution of the connecting rod problem result-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, PNL has reviewed all available information on the subject, and concludes that, provided the check on conrod 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.
22
~
Component: Engine Base and Bearing Cap 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 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, the engine manu-facturer (TDI) reported that this failure was due to impurities in the casting material that reduced the engine base strength.
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.
MP&L Status Durirg the June 1984 inspection liquid penetrant techniques were used on the main bearing cap-t6 engine base saddle surfaces 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 base assembly is acceptable for the first refueling cycle.
l 23 l
7 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 the 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' Group 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 i
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 inspection as described above is l
recommended. For all three groups of heads, barring over before startup is l
recommended.
l MP&L Status During the June 1984 inspection, all heads (all of which are believed to be Group I) on Division 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. MP&L 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.
24 O,
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 start, to check for water leakage into the cylinders.
l 4
i l
25
.M
1 1
4 Component: Jacket Water Pump 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.
l Owners' Group Status Stone & 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 problems have been experienced.
PNL Conclusions Based upon the absence of adverse experience 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.
i r
d 26
,y--
4 w
r 3-
-n
,- y p,me y
,+.c
-,yy,m+--w
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 TDI Service Information Memo No. 361, TDI reported that three engine mounted cables associated with 1) the Woodward governor / actuator, 2) the Air-Pax magnetic
~
pick-up, and 3) the Air-Pax tachometer relay, represent potential fire hazards.
Owners' Group 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 both 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.
p 6
6 e
27 e
e L
i Component: Cylinder Block Part No.: 03-315A Owners' Group Report: FaAA-84-5-4 4
Brief History of Failures Numerous incidents of cylinder block -failures have been reported in the 4
non-nuclear field.
In.the nuclear field, all three engines at Shoreham'have cracks in their cylinder blocks. At Comanche Peak, 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.
Owners' Group Status Failure Analysis Associates perform.ed strain gauge testing combined 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 will e
j initiate between stud hole and line counterbore. Cracks are f
predicted to be benign.
l Cracks between stud hole and liner counterbore will increase 'likeli--
e hood of cracks developing between stud holes of adjacent cylinders.
The deepest crack measured in this region (5-1/2 inches in depth at Shoreham) did not degrade engine operation or loosen studs.
Provided there are no cracks between stud holes between adjacent o
]
cylinders, the block is predicted to have sufficient margin to q
withstand-a LOOP /LOCA event, i
The FaAA report recommends inspections of cylinder blocks at intervals t
j related to load and operating hours.
i MP&L Status At the June 1984 inspection, the Division I cylinder block was inspected
{
in all critical areas by liquid penetrant as recommended by the Owners' Group. No critical indications were observed.
1 28
{
h
PNL Conclusions After reviewing the FaAA repor.t and noting that MP&L found no 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.
e a
29
/.
Component: Cylinder Liner Part No.:
02-315-02-0G
~
Owners' Group Report:
FaAA 84-5-4 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 contributing factor in liner stresses.
MP&L Status During the June 1984 inspection all liners were inspected, deglazed, and reinstalled. Dimensional inspections of the liners were performed by MP&L to ensura that the clamping force of the cylinder head on the liner would not induct 1xcessive stress on the cylinder block.
PNL Conclusions Based upon the MP&L inspection and determination of correct dimensions, as well as upon PNL's onsite inspection during the June 1984 plant visit, PNL concludes that the liners are acceptable for the first refueling cycle.
9 1
30
i 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 appropriate correc-tive action. Therefore, PNL concludes that the low-pressure fuel lines are properly supported and are acceptable for the first refueling cycle.
I f
i i
4 31 k
a
l Component: Crankcase Capscrews 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 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 11 engines. MP&L has also provided for proper preload of crankcase capscrews to be measured periodically.
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 prevent broken capscrews from entering the generator. Therefore, PNL recommends that the crankcase capscrews be accepted for the first refueling cycle.
j 32 1
I
(
Component: Fuel Oil Leaks; Air Start Valve Failures; Air Start Valve l
Solenoid Failures; Fuel Oil Injection Pump; and Division'I i
Engine Failures to Start i
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 MP&L 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.
j PNL Conclusions l
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 has 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.
T 6
l I
33
4.0 ANALYSIS OF THE REQUIREMENT FOR DIVISION II ENGINE INSPECTION In the 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 QA records, that the two engines have similar "as-manufactured" quality.
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 turbochargers 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 considerations:
~
\\
34
1 the similarity of the design and as-manufactured quality of the two diesel engines s
the similarity of the post-manufactured upgrades accomplished for e
each of the two engines l
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 PHL 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. MP&L 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, th e 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 66% fewer starts and i
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 rods have been subjected to approximately 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> of operation since the bolt preloading was last checked.
4.2.2 PNL Conclusions On the basis of the review conducted by MP&L on the manufacturer's QA records and the upgrade accomplished for both engines, PNL concludes that the 35 J
i
Division I and II engine components are of comparable "as-manufactured" quality. On the basis of the operating history, PNL concludes that the engines 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 implement the same enhanced surveillance and maintenance program on the Division I and II engines to maintain their equivalence.
Y O
36
O 5.0 REVIEW 0F 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:
10 modified starts (a) to 40% load (i.e., 40% of nameplate rating) e 2 fast starts (b) to 70% of nameplate rating e
one 24-hour run at 70% of nameplate rating.
e
~
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:
e 10 modified starts to 50% load
- 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 '4RC 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 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.
a.
37
i 3
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.
4 1
i l
a 38
)
l j
6.0 REVIEW 0F THE PROPOSED AUGMENTED MAINTENANCE / SURVEILLANCE PROGRAM In a letter dated April 16, 1984, to C. Berlinger, PNL identified elements of a maintenance / surveillance (M/S) program that ejuld 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 17, 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 1 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 D/G Owners' Group to the satisfaction of the NRC."
The MP&L proposed program differs somewhat from the NRC staff recommendations. The differences are aimed at reducing the time that the engines would not be available 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 i
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
~
i differences between the NRC guidance of April 25 and the July 5 proposal by MP&L.
f f
I 39
TABLE 1.
Comparison of NRC and MP&L Proposed Maintenance / Surveillance for Key Components of the GGNS TDI Engines s
Component NRC Guidance (April 25)
MP&L Proposal (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 hours operation, or is first at the first refueling outage, whichever 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 / fixtures 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:
Lube oil filter differential Lube 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 refueling Operations:
Operations:
Exhaust 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. The 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, including 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 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 that 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 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 MPAL analysis of the adverse impact of more frequent inspections on engine availability.
6.1.3 Lube Oil Checks j
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
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.
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 / Fixtures 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 thaa 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 hours0.00313 days <br />0.075 hours <br />4.464286e-4 weeks <br />1.02735e-4 months <br /> 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, and 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 chance of changes in the condition 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 noted in frequency of measuring 42
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:
I
" lube oil pressure" to " engine inlet lube oil pressure" e
" combustion air L.B. pressure" and " combustion air R.B.
e pressure" to " air manifold pressure L.B. and R.B."
" 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
e add " engine load" as a new item.
- p. 59, MP&L Proposed 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.
j 6.2 PNL CONCLUSIONS PNL concludes that the MP&L proposed M/S activities need some modifica-tions to provide adequate assurance of engine reliability / operability.
The modifications are discussed in detail above in Section 6.1.
In summary they are:
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 e
shutdown and prior to planned engine starts.
43 e
n.
-.._n-,
,m.-_
p.
-,.+
1' connecting rods - Revise retorquing frequency to 200 hou'rs or e
9 months, whichever occurs first. A retorquing check should be performed on the Division II engine prior to plant operation.
lube oil checks - Add that a lube oil sample will bc obtained while e
engine is running.
e studs / fixtures - Modify to assure that 100% of the air start valve capscrews will be retorqued on the schedule indicated.
additional surveillance - Provide changes as detailed above in e
Section 6.1.6.
With these modifications, the MP&L proposed M/S activities are considered acceptable for the first refueling cycle.
l T
r i
i i
44 l
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 j
3 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.
4 7.1 LIMITED ENGINE REQUIREMENTS I
}
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 1
I psig.
7.2 NRC CONCURRENCE WITH ADDITIONAL MP&L SUBMITTALS l
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:
an inspection report confirming that the turbocharger turbine nozzle e
bolt failure was due to intergranular stress corrosion a submittal describing in detail the method used and the results to 1
e confirm the surface area contact of the serrated surfaces of each i
connecting rod-is at least 75%
documented results of measurements of the cylinder head firedeck e
surface flatness the inspection and engineering evaluation reports confirming the e
acceptability for continued service of the two cylinder heads that contain cracks in the stellite seats a submittal identifying the design of cylinder head replacement studs e
I 45 l
j
+
MP&L documentation of the indications noted and the engineering e
dispositionconcerningthereljtivemotionbetweenthepistoncrown and skirt documented crankshaft deflections relative to TDI specifications e
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 documented preturbine exhaust temperatures relative to the e
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.
I 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.
46
PNL-5201 DISTRIBUTION No. of No. of Copies Copies i
0FFSITE 2 DOE Technical Information Center 17 Division of Licensing Office of Nuclear Reactor K. Trickett, NE-14 Regulation U.S. Department of Energy U.S. Nuclear Regulatory Office of Nuclear Energy Commission Washington, DC 20555 Washington, DC 20555 ATTN:
C. Berlinger (10)
ONSITE M. Carrington (2)
R. Caruso DOE Richland Operations Office D. Corley D. Eisenhut M. Plahuta F. Miraglia M. Williams Pacific Northwest Laboratory 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 D. 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 Division of Technical J. Alzheimer Information and Document M. Clement Control S. Dahlgren i
Washington, DC 20555 D. Dingee R. Dodge NRC Public Document Room W. Gintner W. Laity (15)
J. Nesbitt F. Zaloudek Technical Information (5)
Publishing Coordination (2)
Distr-1
__-___ _