ML20101R593

Comment on Proposed Rule 10CFR50 Re Loss of All Alternating Current Power & Draft Reg Guide 1.9,task DG-1021.Opposes Rule

ML20101R593
Person / Time
Site:	Oconee, Mcguire, Catawba, McGuire
Issue date:	07/06/1992
From:	Tucker H DUKE POWER CO.
To:	NRC OFFICE OF THE SECRETARY (SECY)
References
FRN-57FR14514, RTR-REGGD-01.009, RTR-REGGD-1.009, RULE-PR-50, TASK-DG-1021, TASK-RE 57FR14514-00021, 57FR14514-21, NUDOCS 9207160093
Download: ML20101R593 (4)

Text

w ll m ',',; . i s . 5 E O PROPOSED RULE 5g l Duk3 Pso:t Ccmpany P.O. Bor 1006 (5 7 Ffl l'/ 5l'/) 'i^t s. TuCxnR Senior Vice President Charlotte. N.C. 28201-1005 1-OL6CED Nuclear Generation uWC (704) 382-4531 DUMEPOwen '92 JLL 13 P4 :08  ;

July 6, 1992 nnU 1 Lim it -

r y y,t W . L.

Sacretary of the Commission U '"

U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Docketing and Service Branch subjects oconee ruclear Station Docket Numbers 50-269, -270, and -287 McGuire Nuclear Station Docket Numbers 50-369 and ~370 Catawba Nuclear Station Docket Numbers 50-413 and -414 Duke Power Company Comments on the Proposed Revision to 10 CFR 50.63, " Loss of All Alternating Current Power" The following discussion is in response to the NRC's request for comments on the proposed revision to the subject rule as it applies to emergency diesel generator (EDG) reliability. These comments are offered in consideration of determining a realistic approach to improving EDG reliability.

Backaround The proposed rule and accompanying Regulatory Guide 1.9, Revision 3 are results of discussions and negotiations regarding 1.00 reliability that began with the station blackout (SBO) issue. The SB0 issue highlighted that EDG reliability was a large contributor to core acit probability, and the industry committed to improve EDG reliability through Generic Issue B-56. A Nuclear Management and Resources Council (NUMARC) group and an NRC group worked on this issue concurrently, with the goal to develop a reliability plan that could be adopted by both groups. The result was that two plans were developed simultaneously;- Appendix D. to NUMARC 87-00 descrtPes the industry position on EDG reliability, and draft Regula;ory Guide 1.9, Rev. 3, describes the NRC's position. It was the intent of industry that the Regulatory Guide would incorporate by reference the contents of Appendix D of the NUMARC document; however, this was not the case.

Much erfort went into discussions between NUMARC and the NRC on how reliability could be improved (especially in light of the recent industry figures which place reliability at 98%+) . At the heart of .

the discussions was the issue of accelerated testing, which industry believes and NRC studies (NUREG-4590) confirm is one of the leading-causes of EDG unreliability, g71g093920706' SO 57FR14514- PDR -

e U. S. Nuclear Regulatory Commission July 6, 1991 Page 2

, hecific Comments The issuance of the Regulatory Guido as a rule is not warranted.

Development and use of a reliability program using NUMARC 87-00, Appendix D as guidance and elimination of accelerated testing will improve or maintain current reliability. Significant improvement of EDG reliability beyond the 98%+ level currently being experienced is an unrealistic expectation. We believe that development of reliability programs using the NUMARC document as guidance with the elimination of accelerated testing is a much more effective means of improving reliability than the issuance of fines on a daily basis until a specified number of successfu' starts is reached. Much of the intent of the rule is duplict d by the maintenance rule. In addition, in order to meet certain requtrements of the proposed Guide, it is extromely possible that set.e utibtles would have to install a " swing" diesel that may cost anywhere from $20 million to $ 100 million, depending on the site-specific circumstances and license requi ements. This clearly exceeds the scope of the current backfit analysis.

There is redundancy and overlap with the proposed 3 in 20 failure reporting requirement and the 4 in 25 " problem diesel" requirement.

It is recommended that the 3 in 30 be used as an early warning indication only, with no reporting requirement. Twenty demands repr6sents too small a sample size to be statistically meaningful for use as anything but an early _ warning mechanism. The corrective action for the 4 in 25 " problem diesel", 7 consecutive starts, is acceptable; however the rule should consider giving utilities the flexibility to decrease this number or use simulated testing, depending on the resolution of the root cause of the valid failures. The problem diesel trigger would then be acceptable as proposed. In addition, Duke believes that reporting each diesel failure, as is currently the practice, serves'no useful purpose.

Duke recommends instead that a report be prepared upon reaching the 4 in 25, 5 in 50, and 8 in 100 triggers. This meets the intent of providing a rew;nable and useful amount of information when it is needed. This is especially true as it relates to the requirement to make a 4-hour r sation after a valid failure. Determining if a failure is v31'< or invalid can be an intricate process, taking on the order c! dayo rather than hours.The statement should be corrected to state that a notification is required 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> af ter the failure is determined to be valid rd a double trigger is exceeded. This will prevent many notifications that would otherwise be made in error.

The regulatory consequences for exceeding the double trigger are too severe. Imposing a Sever.ity Level III violation and potential fines for each day that a "' t exceeds a double trigger will be a signal to promote fast acti, not quality

Y U. S. Nuclear Regulatory Commission July 6, 1991 Page 3 action. This proposed aspect of the regulation should be deleted.

As previously noted, +ccelerated testing of the EDGs has been shown to do more harm thau good; the constant testing, in some cases every 3 days for 2 years, has actually added to the overall unreliability of the machines. The proposed Guide rGquires accelerated testing when a double trigger and problem diesel trigger are exceeded. This is in direct conflict with the purpose of increasing reliability. This form of testing should be deleted.

In lieu of this testing, Duke Power recommends the actions specified in NUMARC's 87-00, Appendix D as the appropriate action for recovery when a double trigger is exceeded. ,

The last paragraph of Section 2.1 should be clarified such that the post-m rintenance test to declare the EDG operable does count if successful. If not successful, the test would not count and further troubleshooting would be pursued.

Equipment unavailability is addressed in the Maintenance Rule and the use of INPO industry-wide Plant Performance Indicator Program.

Therefore, unavailability should not be addressed again in the proposed rulo. Reliu ility and unavailability-are competing goals and the NRC should not-promote reduction of prudent maintenance activities to increase availability at the expense of reliability.

As an example, the proposed rule indicates that the NRC assumed that EDG availability exceeds 99.3% as a part of the resolution to SBO. The proposed rule further assumes that this availability level will be achieved during power operation and during refueling outages. The latter is a drastic change from current practice, m' ability to perform maintenance or. EDGs, especially during n a y .ss , is necessary. High reliability in EDGs is only partially

. 'ed through condition monitoring. On a per nuclear unit an r uvailability level of .007 is about 61 hours7.060185e-4 days <br />0.0169 hours <br />1.008598e-4 weeks <br />2.32105e-5 months <br /> per year W nuclear unit's diesels may be out of service. The current Mw ry median of unavailability is about .017. Therefore, the

.P is grossly insufficient and will result in degraded re:.ubility.

Table 1 of the Regulatory Guide allows tests 2.2.6 through 2.2.13 to be performed every 10 years. Currently, these tests are performed every refueling outage. This is a positive aspect of the Guide. Itowever, some of these tests should be performed whenever a significant adjustment is made to the generator excitation or governor subsystems. _In addition, the-Guide should incorporate enhancements to testing allowed by Generic Letter 84-15 that permit slow starting of the engine and eliminate many of the detrimental effects of fast starting The Guide should also address and permit the use of simulated testing in lieu of actual testing of the engine. This is especially important for certain subsystems such as controls Furthermore, the Guide should specify the conditions required to restart on the hot start test as well.

l

.- -. . = . _ . . - . _. - _

J

i l U. S. Nuclear Regulatory Commiss' ion July 6, 1991 Page 4 i

1. Thank you for this. opportunity _to comment onfthis-proposed ~ rule.

If-there are any questions, please call-Scott-Gewehr at (704) 373-7581.

} Very truly yours, i

~m

?JN //n t&c..- ,

a ,_

^

?

L /

Hal B. Tucker

! cc: Mr.'T. A. Reed, Project Manager Offics of-Nuclear Reactor-Regulation U. S. Nuclear Regulatory Commission Mail Stop 14H25,_OWFN Washington, D. C.- 20555

Mr. L. A. Wiens,-Project Manager

Office of Nuclear Reactor Regulation

! U. S. Nuclear Regulatory-Commission Mail Stop 14H25, OWFN-l Washington, D. C.- 20555 Mr. R. E. Martin, Project Manager i office of Nuclear Reactor Regulation i U. S. Nuclear Regulatory Commission ~

! Mail Stop 14H25, OWFN.

Washington, D. C. 20555 l

i Mr. S. D. Ebneter, Regional Administrator

! U.S. Nuclear Regulatory Commission --Region II 101 Marietta. Street, NW - Suite 2900 Atlanta, Georgia 30323 l Mr. Aleck Serkiz i

Office of Nuclear. Regulatory Research l U. S.LNuclear Regulatory Commission

! Mail Stop NLS314

[_ Washington, D. C. 20555 l

1

)

i 1

- . - .- . , . - . - , . _ . - - , - . -. - . . - - - . - - . . - - - , .