ML20210D408
| ML20210D408 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 09/15/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20210D401 | List: |
| References | |
| NUDOCS 8609190184 | |
| Download: ML20210D408 (5) | |
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UNITED STATES 8
NUCLEAR REGULATORY COMMISSION o
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-l WASHINGTON, D. C. 20556
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SAFETY EVALUATION BY THE OFFICE OF NOCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.10 TO FACILITY OPERATING LICENSE NPF-?5 i
AND AMENDMENT NO. 3 TO FACILITY OPERATING LICENSE NPF-52 CATAWBA NUCLEAR STATION, UNITS 1 AND 2 f
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INTRODUCTION By letter dated March 24, 1986, Duke Power Company, et al., (the licensee) 2-proposed changes to the Technical Specifications -(TS) for the diesel gener-ators.(DGs) at Catawba Nuclear Station, Units 1 and 2.
Supplemental letters dated June 30, 1986, and July 28, 1986, provided clarification to scme of the changes requested in the March 24, 1986, letter. The proposed changes are related to the testing requirements for the DGs as well as changes to the DGs' fuel oil storage requirements. The licensee's request is in accordance with the staff's guidance outlined in Generic Letter 84-15. The licensee has also f
used the technical specifications approved for the North Anna and Perry Nuclear Plants as a basis for the proposed changes to TS 3/4.8.1,"A. C. Sources," and 4
its associated bases.
EVALUATION l
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(a) The amendments change TS 3.8.1.Ib.1), b.2). 3.8.1.2b'.1) and b.2) to reflect new fuel oil storage requirements. based upon the 5750 kw rating for the DGs. The previous fuel oil volumes were calculated based upon the DG original rating of 7000 kw. The NRC Staff's Supplement 4 to the Catawba SER evaluated the change in the rating of the DGs. The r.ew 1teit of 5750 kw for j
i each diesel was found acceptable to cover all necessary LOCA and blackout i
loads. There are no current plans to return the diesels' rating back up to 7000 kw since the lower rating is adequate and also causes less wear during testing. The staff has evaluated the fuel consumption rate for' the lower DG rating in light of the guidance provided in Se:: tion 5.4 of ANSI N195-1976,
'" Fuel Oil Systems for Standby Diesel Generators", and finds the reduced fuel oil volumes acceptable.
1 (b) The amendments change action statements 3.8.1.la., b., c., and d. to require that the operability of a DG be demonstrated by both starting it and.
i running it loaded on the offsite power system. The previous TS required.that L
is only be started. The proposed change to load the DG is made to reduce the i
amount of diesel generator operating time under detrimental no-load or light-load co..Jitions. The staff finds this change to be a factor. in reducing operation of the DG under conditions which are known to produce detrimental.
i effects and is, therefore, acceptable. This change is also in accordance with previously approved TS for North Anna and Perry Nuclear Plants, r
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J (c) The amendments change action statements 3.8.1.la. and b. to delete the previous requirement to demonstrate that one DG is operable for loss of an offsite circuit or loss of an offsite circuit and the other diesel gener-ator provided it has bee.n successfully tested within the past 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The staff fir.ds that this chenge reduces unnecessary testing and the associated detrimental effects of frequent starts and is. therefore, acceptable. This change is.also in accordance with previously approved TS for North Anna and Perry Nuclear Plants.
(d) The amendments change action statements 3.8.1.la., b., c., and d.
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- to extend the length of time allowed to demonstrate that a diesel generator is operable from I hour in all cases to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> for the loss of two power sources (offsite or onsite) and 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> for the loss of one power source.
The previous requirement to retest at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> is also eliminated. The staff finds that these changes provide sufficient time to perform an orderly start and loading tast on the DGs, reduce unnecessary l
testing and the associated detrimental effects of frequent starts and are, therefore, acceptable. This change is also in accordance with the guidance l
provided in Generic Letter 84-15 and with previously approved TS for North Anna and Perry Nuclear Plants.
(e) The amendments change action statement 3.8.1.lb. and c. to elimi-nate the need to demonstrate the operability of a diesel generator when its e
i redundant counterpart is inoperable due to preplanned testing or maintenance.
j The staff finds that this change reduces unnecessary testing and the asso-ciated detrimental effects of frequent starts and is, therefore, acceptable..
This change is also in accordance with previously approved TS for North Anna i
and Perry Nuclear Plants.
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i (f) The amendments change action statements 3.8.1.lb. and c. to add a i
footnote that requires that surveillance testing on a redundant diesel gen-i erator be completed regardless of when the inoperable diesel generator is restored to operability. The staff finds that this change ensures that both diesel generators are tested for consnon-mode failures which may have caused the initial inoperability of the first DG and is, therefore, acceptable.
This change is also in accordance with previously approved TS for North Anna i
and Perry Nuclear Plants.
(g) The amendments change action statement 3.8.1.1c. to combine the statement for the loss of one diesel generator with the action statement re-quiring that components powered from the redundant diesel generator be detennined operable. This change is editorial and does not result in any changes to the actions required by the operator. Therefore, it is acceptable.
(h) With regard to the changes made in Table 4.8-1, titled " Diesel Generator Test Schedule " the first specific proposal is to change the basis for the testing schedule from "a per nuclear unit basis" to "a per diesel generator basis." The second proposal is to reduce the test frequency for
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an individual diesel generator based on the number of failures from the present minimum interval of once per three days to a minimum of once per seven days.
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The objective of testing the diesels en a regular basis is to ensure the DGs' operabflity by ' timely failure detection aridinecessary corrective action. Such testing provides a degree cf assurance of tte DGs' availability during the periods between tests. Therefore, the existing and the previous DG testing concepts are that the above assurance has to be demonstrated with mare frequent testing as the nurrber of DG failures increases. Thus, the existing and the previous TS require that diesels be tested u ti:at the int;erval depends on the demonstrated DG performance, i.e., the interval shortens as the number of failures increases. Furthermore, the previot 5 test interval is established conservatively cn a per nuclear unit basis, rather than on a per diesel be'is.
s Thus, improper diagnosis of a DG failure cculti potentially rtasult in more fre-quent testing of all the DGs. Also, test intirvals that are too short could have an adverse impact on DG reliability.
Past experience has shown that many licensees have been frequently te. sting their good DGs mainly to quickly get out of the frequent test cycles imposed by the TS. The staff cnd industry agree that current requirements for testing of good DGs do not improve reif abiliif of the good DGs and may be a factor in potentially degrading them. Also, ecessive testing may have negative effects on the overall expected life of the DG's and, hence, such testing is not warranted. Therefore, the staff agrees with the licensee's propcsd to count DG failures on a per DG basis rather than on a per nuclear unit basis and that the frequency of testing a DG will be based on the number of its own failures.
This is consistent with the g'uidance provided in Generic Letter 84-15 on DG reliability. Thus, the staff finds that these proposed changes are acceptable because they improve DG reliability and.are not detrimental to the health and safety of the public.
In addition, the staff has for sometime been evaluating the frequency of DG testing and the associated potential for severe degradation of engine parts due to frequent fast start testing. The staff concludes that the test fre-quency can be reduced to minimize this potential without affecting the overall DG reliability. Therefore, the staff finds that the licensee's proposal to reduce the test frequency for an individual diesel generator, based on the number of failures, from the present minimum intervai of once per three days to a minimum of once per seven days is acceptable.
This is consistent with the guidance provided in Generic Letter 84-15 on DG reliability.
The final change proposed in Table 4.8-1 would provide an explicit direct incentive if the licensee performs a thorough and comprehensive complete overhaul (the DG would be rebuilt to like-new conditions) of the DG that is approved by the DG manufacturer.
Following such an overhaul and the one--
time satisfaction of the appropriate surveillance tests, the licensee would not be required to count previous failures of that DG if an acceptable re-liability can be demonstrated. With "no previous failures" in the past 20 or 100 tests, the DG would re-enter the test schedule at the monthly test frequency. Accelerated testing (weekly) would not become required until either 2 failures in 20 tests or 5 failures in 10G tests occur. The staff finds that this change is acceptable because a thorough and complete overhaul of a DG, that has experienced excessive number of failures, wculd potentially provide for better reliability.
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The proposed reliability criterion for the rebuilt DG is the successful com-pletion of 14 consecutive tests, at least 4 of which would be " fast cold" starts. Statistically, the probability that.a DG with an actual reliability of less than 0.90 demand will satisfy this 14-test criterion is no greater than 20% and decreases rapidly with the actual reliability. The probability L
i that a DG with an actual reliability of less than 0.95 will satisfy the 14-test criterion is 42% or less. Said in the converse, if the rebuilt DG passes the 14-test criterion, the statistics would indicate that the proba-bility that the actual reliability of the DG is 0.95 or better is about 50%
i and that the probability that the actual reliability is 0.90 or better is 1
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about.90%. The staff, therefore, finds the proposed 14-test criterion to be acceptable. A note of caution should be added regarding repeated attempts to satisfy the 14-test criterion because in such a case the statistical situation i
changes.
If a DG passes the criterion on a second attempt, the probability that the actual reliability is 0.95 would be reduced to only about 25%.
t Therefore, if the 14-test criterion is not passed on the first attempt, tne previous test failures remain in effect. This is specifically required as j
part of the reliability test criterion in the current Table 4.8-1 and is, therefore, acceptable.
4 (1) The amendments change TS 4.8.1.1.Ib. and 4.8.1.1.2. to allow cer-9 I
tain surveillances to be conducted during unit operations. TS 4.8.1.1.lb.
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previously required that both of the offsite circuits be demonstrated operable at least once per 18 months during shutdown by transferring (man-ually and automatically) Unit power supply from the nonnal circuit to the i
alternate circuit. The licensee proposed to delete the words "during shutdown" from the requirement.
TS 4.8.1.1.2. previously re
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all the diesel generator surveillances listed underneath it (quired that1 thru 14) be 9
perfonned at least once per 18 months during shutdow'n. The licensee pro-i posed to delete the words "during shutdown" from the general requirement in TS 4.8.1.1.29 and has added them only to the specific surveillances in 4.8.1.1.2g.1) 4),.6),.7),.8),.9), and.10).
In the March 24, 1986 letter, the licensee stated that an override signal would be generated and the diesels would be capable of carrying out their intended functions during j
all the surveillances that now may be conducted during unit operation. The staff, therefore, finds these changes acceptable.
(j) The amendments delete the footnote from TS 4.8.1.1.2.d regarding i
the operability of the cathodic protection system. The required date for the system operability has passed and the system is now operable. Thus, the footnote is no longer needed.
The amendments revise Bases Sections 3/4.8.1, 3/4.8.2, and 3/4.8.3 to in-clude a discussion regarding the industry's increased experience with DG degradation due to excessive testing and to reference Generic Letter 84-15 titled " Proposed Staff Actions to Improve and Maintain Diesel Generator i
Reliability." We find the revised bases, as' proposed in the licensee's letter of March 24, 1986, to be equivalent to those in Generic Letter 84-15.
Therefore, the revised bases are acceptable.
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ENVIRONMENTAL C0hSIDERATION The anenaments involve a change in use of facility components located within the restricted area as defined in 10 CFR Part 2G ano changes in surveillance requirenents. The staff has deterr.ined that t.he amendments involve no signi-ficant increase in the amounts, and no significaat change in the types, of any effluents that may be released offsite and that there is no significant in-crease in individual or cumuletive occupational exposure.
The Ccenission has previously issued a proposed finding that the amenduents involve no significant hazards consideration, and there have been no public conrents on such finding.
Accordingly, the amendments meet the eligibility criteria for categorical ex-clusien set forth in 10 CFR Section 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statenent or environmental assessnent need be prepared in connection with the issuance of the amendments.
CONCLUSION t
The Conmission made a proposed determination that the eraendaents involve no significant hazards consideration which was published in the Federal Register (El FR 22233) on June 18, 1986, and co sulted with the state of South Carolina.
n Ne public comments were received, and the state of South Carolina dio not have any cocments.
We have concluded, based on the considerations discussed above, that: (1) there is reascnable assurance thet the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations, and the issuance of the amendrents will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors: Kahtan Jabbour, FWR#4/DPWR-A James Lazevnick, EICSB/0PWR-A Robert Giardina, PSB/DPWR-A Dated: September 15, 1986 P