ML20036A535
| ML20036A535 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 04/29/1993 |
| From: | Tuckman M DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| RTR-NUREG-1216 NUDOCS 9305120044 | |
| Download: ML20036A535 (15) | |
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A Duke Pourr Company M.S Tucatx Carextra Nuclear Cenmwn Department l' ice President 4Miri Concord Road (M3)S313205 Offire tbrk, SC23745 (M3)S31-3126 hk DUKEPOWER April 29,1993 U. _S. Nuclear Regulatory Commission ATIN: Document Contml Desk Washington, D. C. 20555
Subject:
Catawba Nuclear Station, Units 1 and 2-Docket Nos: 50-413 and 50-414 Operating License Amendments Emergency Diesel Generator Maintenance and Surveillance Gentlemen:
Attached am pmposed amendments to the Catawba Nuclear Station Facility Opemf 6g Licenses for Units I and 2, NPF-35 and NPF-52, mspectively.
The attachment outlines proposed amendments that would remove licensing conditions for the.
1 Emergency Diesel Generators (EDGs) imposed as a result of NUREG-1216, Safety Evaluation Repor1 Related to the Ooerability and Reliability of Emergency Diesel Genemters Manufactured by Transamerica Delaval. Inc. These licensing conditions require that the engines be torn down in order to perform inspections which, as noted in the attachment, degrades the reliability and j
availability of the EDGs. The inspections that have been performed to date have not shown any i
significant wear pattems or problems that could not have been detected by other means (e.g.,
trending opentional parameters).
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The TDI Owners Group docketed its generic submittal concerning this issue in a letter fmm J.B.
George and C.W. Hendrix to the NRC Document Contm!_ Desk on December 8,1992 and it is -
currently being reviewed by the ONRP.'s Electrical Branch. The generic submittal and this
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Catawba-specific request together pmvide the basis for the Catawba license amendment. The reviews of these two submittals should therefore be performed cencurrently.
Unit l's next refueling. outage is currently scheduled to begin on October 8,1993. Itis requested that this amendment be approved by September 30,1993 in order to avoid teardown of the Unit I engines.
Pursuant to 10CFR50.91(b)(1),' the appropriate South Carolina state official is being provided a copy of this amendment request.
I 9305120044 930429 l
PDR ADOCK 05000413 P
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i Document Control Desk Page 2 April 29,1993 h
If you have any questions pertaining to this amendment request, please call L.J. Rudy at (803) 831-3084.
Very truly yours, M.S. Tuckman IJR/s Attachment xc:
S.D. Ebneter, Regional Administrator Region II W.T. Orders, Senior Resident Inspector R.E. Martin ONRR i
Heyward Shealy, Chief Bureau of Radiological Health, SCDHEC American Nuclear Insurers M&M Nuclear Consultants INPO Records Center j
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Document Control Desk i
Page 3 April 29,1993 M.S. Tuckman, being duly swom, states that he is Vice President of Duke Power Company, Catawba Nuclear Site; that he is authorized on the part of said Company to sign and file with the Nuclear Regulatory Commission this revision to the Catawba Nuclear Station Facility l
Operating Licenses, License Nos. NPF-35 and NPF-52; and that all statements and matters set fonh therein are tme and correct to the best of his knowledge.
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M.S. Tuckman, Vice President i
Subscribed and swom to before me this 29th day of April,1993.
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Njdtary'Public //
i My commission expires:
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ATTACIIMENT DUKE POWER COMPANY CATAWIIA NUCLEAR STATION, UNITS 1 AND 2
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Proposed License Amendments To Facility Operating Licenses NPF-35 And NPF-52 "TDI Diesel Engines Requirements" l
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Requested Amendments t
Remove Facility Operating License NPF-35 (Unit 1) License Condition 20 which reads as denoted in Attachment A to this mquest.
Remove Facility Operating License NPF-52 (Unit 2) License Condition iI which reads as denoted in Attachment A to this request.
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IIACKGROUND The TDI Owners Group was fwined in late 1983 following the cankshaft failum of an Enterprise emergency diesel generator (EDG) at the Shomham Nuclear Plant. Thb Owners Group developed a detailed Program Plan to provide for design review and quality revalidation j
(DR/QR) of the Enterprise EDG. This plan was reviewed and approved by the NRC in a Safety Evaluation Report dated August 13,1984. Following issuance of the SER, the Owners Group member utilities developed and implemented the DR/QR in msponse to and in accordance with the Program Plan. The specific details of the DR/QR were submitted to the NRC for review and the results of this review were documented in NUREG-1216. NUREG-1216 outlines specific provisions that were incorpomted as conditions of license for Catawba. It is these specific conditions of license that Catawba is requesting be deleted. The conditions of license were required for Catawba since little operating history of these engines.was available at the time of the DR/QR review. Since that time, the industry has collected over 9000 hours0.104 days <br />2.5 hours <br />0.0149 weeks <br />0.00342 months <br /> of operation of these engines. The inspections mquired by the license conditions for Catawba and -
other nuclear units with TDI EDGs have shown no problems from opemtion of the engines, and many utilities find that more damage is being imposed during the inspection / teardown procedtire than fmm operation. The basis for these statements is documented in the generic submittal of'-
the TDI Owners Group entitled, Generic Licensing Submittal for Emergency Diesel Generators.
Conditions of License for Utilities with Entemrise Engines, dated December 8,1992 in a letter from J.B. George and C.W.- Hendrix to the NRC Document Contml Desk (hereinafter referred to as " generic submittal"). This document is incorporated by refemnce to this request for license '
amendment and is the basis under which deletion of the conditions of license identified above is sought.
l The pertinent license condition history for the Catawba engines is delineated in the following three license amendments:
1.
Amendment 16 to NPF-35 (Unit 1) issued on October 21, 1986 incorporated the -
recommendations and conclusions contained in the NRC SER on opembility/ reliability l.
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e of TDI diesel generators, published as NUREG-1216.
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Amendment 18 to NPF-52 (Unit 2) issued on May 26,1987 changed the Unit 2 license conditions to make them identical to the Unit I license conditions with the exception of the inspection of main bearing No. 7 of diesel genemtor 2B.
3.
Amendment 53 to NPF-52 (Unit 2) issued on February 15, 1989 revised the license conditions to delete the requirement for special inspections of diesel generator 2B main bearing No. 7.
3 The proposed amendment will remove those conditions that are no longer necessary to ensure reliable operation based on the inspection history of Enterprise engines at Catawba and the i
inspection history of all Enterprise engines in nuclear service.
This combined history.
demonstrates that the Enterprise engine has achieved a level of reliability in nuclear service similar to that of other manufacturers and that special inspection mquirements included in the i
plant's opemting license are no longer warranted.
i DISCUSSION i
i The primary function of the EDGs is to pmvide emergency AC power to the vital buses upon l
a loss of offsite power. Providing necessary maintenance to the EDGs is important to assure their continued reliability and availability. Sections 4.0 and 5,0 of the Owners Group generic j
submittal provide the unavailability and unreliability of all Enterprise engines identified in that document. The Catawba engines I A, IB,2A, and 2B are mpresented by Engine 9,'10,11, and.
j 12, respectively, of those tables. These tables include data through June 1992. It should be noted that the most recent data available (through December 1992) shows considerable l
improvement in reliability and availability for Catawba's EDGs. This most recent data is not l
included in the generic submittal which was provided to the NRC. It should also be noted that a ponion of the unavailability and unreliability of the Catawba EDGs results from causes other.
than teardowns. However, the data indicates that reliability and availability can be expected to improve by eliminating engine teardowns.
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The following is an itemiby-item discussion of the conditions of license provided in Attachment A
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-Item 1 - Chances to Maintenance / Sun'eillance Procram and Frequency of Engine Overhauls This item discusses the process for controlling changes to the maintenance / surveillance program for the EDGs. It also specifies conditions governing the frequency of major engine overhauls.
l The requirements of 10CFR50.59 are already a legal and binding commitment for Catawba.
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Catawba has a program in existence to define when and how a review under.10CFR50.59 is 1
conducted and when this review is needed. Maintenance practices and changes to maintenance progmms for all equipment including the EDGs are subject to the provisions of the existing program. Should a maintenance item be judged to have an impact on nuclear safety, the pmvisions of this program would be invoked. Having another license requirement to utilize an existing program covered under other requirements is redundant and unnecessary and Catawba is requesting that this requirement be deleted as a license condition.
In order to be trr/ted as other EDGs, Catawba should have the freedom to change its pmgram as necessary to incorporate enhancements that will increase availability and reliability. This includes the overhaul frequency. Engine overhaul frequency is discussed in Section 3.1 of the generic submittal. Recent studies perfonned for the NRC (NUREG/CR-5057, Acine Mitication
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and Improved Procrams for Nuclear Service Diesel Generators and PNIe6397, Aging of Nuclear Station Diesel Generators: Evaluation of Ooerability and Exoert Experience) indicate that for approximately two years following a major engine overhaul, EDGs, regardless of their manufacturer, exhibit increased unreliability. This increase is attributed to several reasons. One reason is that during disassembly there is a high potential to intmduce dirt and other substances s
that may harm the engine. Another is that disturbing a precision fit system that " wears in" to seat mating surfaces (e.g., rings and liners, crankshafts and bearings, connecting rods and bearings) can result in altemtion of wear patterns that may increase wear or actually cause wear -
to start and decrease the life of the component. The period following overhaul is a " shakedown" period that is required to produce a smooth running reliable engine.
1 The results of the five-year " mini" overhauls at Catawba have shown minimal or no wear on major engine components and very few other component related pmblems. Perfom1ance of a complete engine overhaul on a time-based frequency is not appropriate and can lead to reduced reliability and availability. An overhaul should be perfonned based on condition monitoring and trending analysis and thus a pre-specified interval should not be determined. Based upon this, Catawba is requesting that the requirement to specify an overhaul frequency on a time-dependent.
L basis be deleted as a license condition. It should be noted that deleting this requirement will also be consistent with the implementation of the Maintenance Rule, as the EDG maintenance and surveillance program will become more performance-based and will focus more directly on j
results.
t Item 2 - Inspection of Connecting Rod Assemblies f
' This item discusses the provisiens for inspection of the connecting rod assemblies. This item I
is addressed in the generic submittal in Section 3.52. The data contained in Appendix B of the.
generic submittal includes ~ the results of the Catawba inspections. As noted in the generic submittal, there have been no raajor problems with this component since completion of the DR/QR effon at Catawba or at other utilities.-
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The reason for pmblems with the connecting rods during early opemtions dealt with inadequate i
bolt preload. The results presented in the generic submittal note that many hundreds of checks have been made on connecting rod bolts to determine if any relaxation of preload has occurred -
I during operation. The results show that relaxation has not occurred and the design changes -
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p implemented during DR/QR have been effective in dealing with the concems of this component.
Based on the information presented in the generic submittal, Catawba is requesting that this license condition be deleted.
6 Item 3 -Insoection of Cylinder Blocks
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This licensing condition deals with cylinder blocks. It is noted that a thomugh design review of this component was completed during the initial DR/QR review. A finite element structural model revealed cenain block areas that are subjected to higher stresses than other areas. A i
fracture mechanics analysis revealed that crack initiation is possible in cenain cimumstances; however, these cracks were shown to arrest and not to propagate. These potential cracks were e
found to be in areas that would produce a flow path for water to the block exterior and would be evident by a visual check. It was also shown that some of the block castings made during the construction periods for the Enterprise engines may contain Widmanstaetten graphite which is an inclusion that weakens a grey cast iron casting.
Catawba has tested for Widmanstaetten graphite inclusions and has found no evidence of any of-this material in any of the four blocks on Enterprise engines. Catawba has also perfermed inspections for the block areas exposed during the five-year " mini" overhauls and has found no indications of cracking in the block.
The original design and quality review for this component was noted to be conservative by the l
TDI Owners Group. In addition, PNL-5600, Review of Resolution of Known Problems in Engine Components for Transamerica Delaval. Inc. Emergency Diesel Generators, noted, "If.
cumulative results of these inspections over several power plant fuel cycles show that one or' more of the inspections reveal nothing of significance, the scope and frequency of the inspections 4
could be reconsidered."
As a result of the previous inspections and the fact that no Widmanstaetten gmphite is present, the design review has indeed shown the analysis to be-conservative and that future time-based inspections am not warranted. Futum maintenance' 1
programs will consider inspections any time the block top surface is exposed for other reasons.
This position is supported by the generic submittal, Section 3.10.-
Catawba is therefom requesting that this license condition be deleted.
Item 4 - Performance of Air-Roll Tests i
This item discusses and requires the operation of air mlling the engine prior to any planned stan--
l with the cylinder stopcocks open. The purpose of this requirement is to prevent damage to the l
- engine should a leak occur that would allow fluid into a cylinder creating high hydraulic loads should a start be attempted with this fluid present in the cylinder. Catawba believes this practice l
is valuable and has no intention of deleting this item from its operational procedures. However, i
since the merits of performing this action are well known and understood, it should not be a l
condition of license. Reliability and availability goals are positive incentives for continuing this -
pmcedure. These incentives are recognized by other utilities and provide sufficient justification for their continued practice of this procedure without a fonnal licensing commitment. Catawba t
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a requests that this requirement be deleted as a license condition.
Section 3.12 of the generic submittal addresses concerns related to the Group I, II, and III heads. Catawba has had no major problems with heads in operation and still has in service both Group I and II heads. As a result of the positive operational experience, Catawba concludes that the above position regarding air rolling of the engine is justified.
Item 5 -Insoection of Turbochargers This item discusses periodic inspections of the turbochargers. This item is discussed in detail in Section 3.16 of the generic submittal. The major issues dealing with turbochargers pertain to lubrication and fatigue of stationary vanes in the turbocharger casing.
Regarding the stationary vanes, there has been a total of four cases experienced at other plants and reponed to the TDI Owners Group where missing vanes have been found and these missing vanes have passed through the rotating vane group withe,ut degradation of the turbocharger perfonning its design ftmetion. On January 20,1989, Catawba EDG I A experienced a similar event with no degradation of the turbocharger. Based upon this operational history, Catawba believes that future inspection for this item as a condition of license is unwarranted. Following the deletion of this license condition, Catawba will continue to monitor turbocharger performance using non-disassembly techniques.
Regarding lubrication and bearing wear, the TDI Owners Group recommended design modifications to provide a lube oil system to enable the tmbocharger bearings to be prelubricated prior to any planned start. This enhancement has been implemented at Catawba and has led to increased bearing life. This modification, along with the positive inspection results noted above, provides the basis for removal of this license condition. Catawba is therefore requesting that this license condition be deleted.
SAITTY ANALYSIS The primary function of the EDGs is to provide emergency AC power in the event of a loss of offsite power. The conditions of license discussed previously are for maintenance related activities for this equipment. These maintenance activities affect the reliability and availability of the equipment.
The basis of the TDI surveillance matrix (refer to Appendix A of the generic submittal) deals with preventative maintenance, monitoring, and inspections. Inspections are by far the largest contributor to the significant out-of-service time experienced during outages. In addition, the requirement to perform a complete overhaul every ten years adds to this unavailability, and as discussed above, also adds to unreliability. Elimination of the licensing conditions will actually a.-. - --
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increase availability and reliability by reducing the number of engine teardowns and inspections.
Monitoring of the system health will continue under a program of monitoring and trending similar to the one currently in place. Increasing EDG reliability and availability will serve to reduce the probability of core melt and then fore this amendment request does not involve any adverse safety considemtions.
ANALYSIS OF NO SIGNIFICANT IIAZARDS CONSIDERATION 10CFR50.92 states that a proposed amendment involves no significant hazards considemtion if operation in accordance with the proposed amendment would not:
(1)
Involve a signiGcant increase in the pmbability or consequences of an accident previously evaluated; or (2)
Create the possibility of a new or different kind of accident from any accident previously evaluated; or (3)
Involve a significant reduction in a margin of safety.
In 48FR14870, the Commission has listed seveml examples of license amendments that are considered not likely to involve significant hazards considentions. Example iv describes an amendment that gants relief upon demonstration of acceptable operation from an operating restriction that was imposed because acceptable operation was not yet demonstmted.
The proposed amendment is similar to Example iv in that the license conditions requiring teardown and inspection of the TDI engines were imposed because safe and reliable opemtion of these engines had not yet been demonstrated.
The proposed amendment would not involve a significant increase in the probability or consequences of an accident previously evaluated. Eliminating the required teardowns and inspections has no effect on the probability of an-accident occurring, because the diesel generators are not accident initiating equipment. Eliminating the teardowns and inspections would actually decrease the consequences of an accident, because the availability and reliability l
of the engines would increase as a result of the less frequent teardowns (i.e., the engines would be available more often during outages and the detrimental effects of a teardown on subsequent
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engine opemtion would be minimized).
The proposed amendment would not create the possibility of a new or different kind of accident from any accident previously evaluated. The proposed amendment will not cause any physical i
changes to the plant and the design and operation of the units will not be affected.
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The proposed amendment would not involve a significant reduction in a margin of safety. The
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t proposed amendment will increase the reliability and availability of the EDGs and therefore will not result in a decrease in a margin of safety at Catawba.
ENVIRONMENTAL IMPACT STATEMENT The proposed amendment has been reviewed against the criteria of 10CFR51.22 for environmental considerations. As shown above, the proposed amendment does not involve any significant hazards consideration, nor does it increase the types and amounts of effluents that may be released offsite, nor does it increase the individual or cumulative occupational radiation exposures.
Based upon this, the proposed amendment meets the criteria given in 10CFR51.22(c)(9) for categorical exclusion from the requirement for an Envimmnental Impact Statement.
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i ATTACIIMENT A CURRENT LICENSE CONDITIONS PERTAINING TO TDI DIESEL ENGINES j
FOR CATAWBA UNITS 1 AND 2 i
NPF-35 License Condition 20 and NPF-52 License Condition 11 are as follows:
1.
Changes to the maintenance / surveillance program for the TDI diesel engines, as identified in the licensee's submittals of August 1 and September 11, 1986, shall be subject to the oro-visions of 10 CFR 50.59. The frequency of the major engine overhauls referred to in the lirense conditions below shall be consistent with Section IV.1.
" Overhaul Frequency," in Revision ? of Aooendix II of the Design-Review /0uality Re-validation Report which was transmitted by letter datec May 1, Ic86, from J.B. George, Owners Group, to H.R. Denton, NRC.
2.
Connecting rod assemblies shall be subjected to the following in-spections at each major engine overhaul:
(a)
The surfaces of the rack teeth should be inspected fer signs of fretting.
If fretting has occurred, it should be subject to an engineering evaluation for acoropriate corrective action.
(b) All connecting rod bolts should be lubricated in accor-dance with the engine manufacturer's instructions and turqued to the soecifications of the manufacturer.
The lengths of the two cairs of bolts above the crankoin should be measured ultrasonically before and af ter tensioning.
(c) The lengths of the two pairs of bolts above the crankoin _
should be remeasured ultrasonically before detensioning and disassembly of the bolts.
If bolt tension is less than 93% of the value at installation, the cause should be determined, acoropriate corrective action should be taken, and the interval between checks of bolt tension should be reevaluated.
(d)
All connecting (e.d bolts should be visually inspected for ro thread damage g., galling), and the two pairs of connecting rod bolts above the crankoin should be inspected
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l by magnetic particle testing to verify the continued absence of cracking.
All washers used with the bolts should be examined visually for signs of galling er cracking, and replaced if damaged.
(e) A visual inspection should be performed of all external surfaces of the link rod box to verify the absence of any signs of service-induced stress.
(f) All of the bolt holes in the link rod box should be inspected for thread damage (e.g., galling) cr other signs of abnormalities. In addition, the bolt holes subject to the highest stresses (e.g., the pair innediately above the crankpin) should be examined with an appropriate non-destructive method to verify the continued absence of cracking. Any indications should be recorded for engineerirg evaluation and appropriate corrective action.
3.
(a) Cylirder blocks shall be inspected for " ligament" cracks,
" stud-to-stud" cracks and " stud-to-end" cracks as defined in a report by Failure Analysis Associates. Inc. (FaAAl entitled " Design Review of TDI R-4 and RV-4 Series Emergency Diesel Generator Cylinder Blocks" (FaAA report no.
FaAA-84-9-11.1) and dated December 1984 (Note that the FaAA report specifies additional inspections to be per-fenred for blocks with "krewn" or " assumed" ligarent cracks.) The inspection intervals (i.e., frequency) sFall not exceed the intervals calculated using the cumulative damage index medel in the subject FaAA report.
In addition.
inspection methods shall be consistent with or equivalent to those identified in the subject..FaAA report.
(b)
In adcition to inspections specified ir. the aforementioned FaAA report, blocks with "known" or " assumed" ligarent cracks (as defined in the FaAA report) should be inspected at each refueling outage to determine whether or not cracks have initiated on the top surface, which was exposed because of the removal of two or more cylinder heads.
This process should be repeated over several refueling outeges until the entire block has been inspectea.
Liquid penetrant testing or a'similarly sensitive non-destructive testing technique should be used to detect cracking, and eddy current testing should be used as appropriate to detennine the depth of any cracks discoverec.
(c)
If inspection reveals cracks in the cylinder blocks between stud holes of adjacent cylinders (" stud-to-stud" cracks) or " stud-to-end" cracks, this condition shall be reported promptly to the NRC staff and the affected engire shall be considered inoperable. The engine shall not be restored to " operable status" until the proposed dispositic-and/or corrective actions have been approved by the ARC staff.
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The following air-roll test shall be cerfomed as soecified belw, except when the olant is alreacy in an Action Statement of Tec-nical Specification 3/4.8.1, " Electric Fewer Systems.
A.C. Sources" The engines shall be rolled over with the airstart system and with the cylinder stoccocks ooen before each clanned start, urless i
I that start occurs within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of a shutdown.
The engires shall also be rolled over with the airstart system and with the cylinder stoccocks open after 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, but no more than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, after engine shutdown and then rolled over once again aooroximately ?4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after each shutdcwn.
(If an engine is removed from service for any reason other than the rolling-over orocedure before exoiration of the 8-hour or 24-hour periods noted above, that engire reed not be rolled over while it is out of service. The licensee shall air-roll the engine over with the stoccocks ooen at the time it is returned to service.)
The origin of any water detected in the cylinder must be determined, and any cylinder head that leaks because of a crack shall be replaced.
The above air-roll test may be dis-continued following the first refueling outage sub.iect to the following conditions:
(a) All cylinder heads are Group III heads (i.e., cast af ter September 1980).
(b) Ouality revalidation inscettions, as icentified ir the Cesign Peview/ Quality Revalidation report, have been completed for all cylincer heads.
(c) Group III heads continue to demonstrate. leak-free performance.
This should be confirmed with TDI before air-roll tests are discontinued.
5.
Periodic inspections of the turbochargers shall include the follcwing:
I (a) The turbocharger thrust bearings shculd _be visually insoected for excessive wear af ter 40 nonorelubed starts since the orevious visual inscection.
J (b) Turbocharger rotor axial clearance should be measured at i
each refueling outage to verify comoliance with TCI/Elliott-scecifications.
In addition, thrust bearing measurements should be coroared with measurements taken previously-to determine a need for further inspection or corrective 1
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(cl Soectrograohic and ferrographic engine oil analysis shall be perfortred quarterly to orovide early evidence of bearino degradation.
Particular attention should be paid to coocer level and particulate size, which could signify thrust
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bearino degradation.
(d) The nozzle ring components and inlet guide vanes should be visually inspected at each refueling outage for missirg parts or parts showing distress on a one-turbocharger-per refuelinc-outage basis.
In additien, these inscections should be performed for all turbochargers at each turbocharger overhaul (i.e., at approximately 5-year intervals,.
If any missing parts or distress is roted, the entire ring assembly should be replaced and the subject turbecharger should be reinsoected at the next refueling outage.
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