NL-13-1157, Pilot 10 CFR 50.69 License Amendment Request Response to Request for Additional Information

Pilot 10 CFR 50.69 License Amendment Request Response to Request for Additional Information

ML13184A267
Person / Time
Site:	Vogtle
Issue date:	07/02/2013
From:	Pierce C Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-13-1157
Download: ML13184A267 (11)

Text

Charles R. Pierce Southern Nuclear Regulatory Affairs Director Operating Company, Inc.

40 Inverness Center Parkway Post Offic Box 1295 Birmi ngham, Alabama 3520 1 Tel 205.992.7872 Fax 205. 992.7601 SOUTHERN ' \

COMPANY July 2, 2013 Docket Nos.: 50-424 NL-13-1157 50-425 U. S. Nuclear Regulatory Commission ATrN: Document Control Desk Washington , D. C. 20555-0001 Vogtle Electric Generating Plant Pilot 10 CFR 50.69 License Amendment Request Response to Request for Additional Information Ladies and Gentlemen:

By letter dated August 31, 2012, Southern Nuclear Operating Company (SNC) requested amendments to the Vogtle Electric Generating Plant (VEGP) Units 1 and 2 (TAC NOS ME9472 and ME9473) . The proposed amendments would revise the VEGP licensing basis to implement 10 CFR 50.69, risk informed categorization and treatment of structures, systems, and components for nuclear power plants, By letter dated April 17, 2013, the Nuclear Regulatory Commission (NRC) requested additional information. SNC responded to the request by letter dated May 17, 2013, and noted the responses to requests for additional information (RAls) 19, 25, 26, and 27 would require additional time to develop and would be provided within 120 days from the date of the SNC letter.

The enclosure to this letter provides SNC's response to RAI 19 and 27.

This letter contains no NRC commitments. If you have any questions, please contact Ken McElroy at (205) 992-7369.

U. S. Nuclear Regulatory Commission NL-13-1157 Page 2 Mr. C. R. Pierce states he is Regulatory Affairs Director of Southern Nuclear Operating Company, is authorized to execute this oath on behalf of Southern Nuclear Operating Company and, to the best of his knowledge and belief, the facts set forth in this letter are true.

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Enclosure:

Response to Request for Additional Information Regarding Pilot 10 CFR 50.69 License Amendment Request cc: Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bost, Executive Vice President & Chief Nuclear Officer Mr. T. E. Tynan, Vice President - Vogt/e Mr. B. L. Ivey, Vice President - Regulatory Affairs Mr. B. J. Adams, Vice President - Fleet Operations RType: CVC7000 U. S. Nuclear Regulatory Commission Mr. V. M. McCree, Regional Administrator Mr. R. E. Martin, NRR Senior Project Manager - Vogtle Mr. L. M. Cain, Senior Resident Inspector - Vogtle State of Georgia Mr. J. H. Turner, Environmental Director Protection Division

VogUe Electric Generating Plant Request to Revise the licensing Basis to Implement 10 CFR 50.69 Response to Request for Additional Information Regarding Pilot 10 CFR 50.69 license Amendment Request Enclosure Response to for Additional Information Regarding Pilot 10 CFR 50.69 license Amendment Request

Enclosure to NL-13-1157 Response to Request for Additional Information Regarding Pilot 10 CFR 50.69 License Amendment Request NRC RAI # 19 FSS-C4-01 included observations related to credit for suppression activities and severity factors.

SNC's response stated that SNC's method is consistent with a method that industry had reviewed (the unreviewed analysis method). Please describe the method used. If the method has not been accepted by the NRC, please provide a sensitivity study replacing the unacceptable method with the acceptable method indicating how great an impact this assumption has on the number of SSCs that would have been assigned low safety significant (LSS) but would now be HSS. This should include the standard categorization sensitivity studies (e.g., CCF and HEP evaluations) to the extent that the results of those sensitivity studies could also change.

SNC Response SNC's method is commonly referred to as the electrical cabinet factor method. This method is identified as an unendorsed method used in the Vogtle fire PRA in SNC's response to RAI # 27 (this enclosure). Refer to the table "list of Fire PRA Methods in Debate" under the fire PRA method "electrical cabinet heat release rate or severity factors and cabinet to cabinet fires". Replacement of this "unacceptable method" with a method acceptable to the NRC will be performed as part of the response to RAI # 27.

NRC RAI #27 Please identify and provide technical justification for any fire PRA methodology that has not been formally accepted by the NRC staff. The NRC staff has formally accepted methods during resolution of UAMs as well as NUREG/CR-6850 (as supplemented) or the National Fire Protection Association Standard 805, "Performance Based Standard for Fire Protection for light Water Reactor Electric Generating Plants," frequently asked question guidance. Please evaluate the significance of the use of any method not yet accepted by the NRC Staff on the categorization process. If a position on a method has been established by the NRC, please confirm that the accepted version of the method is used per the NRC position and, if not, then provide a revised analysis and results using an accepted approach.

SNC Response SNC has prepared a tabulation of fire PRA methods that have been in use in the industry and that have been the subject of recent communications relative to Unreviewed Analysis Methods (UAM) and NRC endorsement status. The attached Table shows these methods, identifies their applicability to the Vogtle fire PRA, and identifies SNC's understanding of the current NRC endorsement status.

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Enclosure to Nl-13-11 Response to Request for Additional Information Regarding Pilot 10 CFR 50.69 Amendment Request As in Table, SNC has three fire PRA methods in the Plant Vogtle fire that are unendorsed methods. They are as follow:

• Not using 0.001 as lowest value for failure of manual suppression (using values than 0.001, even 0)

• Not using lower failure threshold for sensitive electronics

• Electrical cabinet heat release rate or severity factors and cabinet to cabinet fires (one method one method commented, others exist)

In addition, as explained below, SNC has identified that the Vogtle fire PRA has used an alignment factor not accepted by NRC staff.

• Although an endorsed method has been used for alignment factor for oil pump fires, the alignment factor used by SNC for oil pump fires is slightly different than the factor accepted by NRC staff in NRC letter dated June 21,2012 (ML12172A06).

With the exception of these four items, is not aware of the use of fire PRA methodology that has not been accepted by the NRC staff.

SNC will remove three unendorsed methods from the Vogtle fire PRA and change the alignment factor for oil pump fires to the factor endorsed by the NRC. The resulting model will refined as necessary using the approved/endorsed methods. model generated will be designated as the Sensitivity model (BCS model).

SNC intends to use the model for the categorization process. Because the not contain unendorsed methods, there will not an impact on the categorization compared to an impact that might have been observed when using a PRA model containing unendorsed methods. SNC intends to use the model to to other RAls that request sensitivity analyses on NRC approved methods (e.g., RAls # and # 26). Each sensitivity study will performed individually.

The total Frequency (CDF) and total Large (LERF) determined from the model will be included in the response to RAls # 25 and # 26 as a measure of the combined effects of removal of the UAMs and as the point comparison for the requested sensitivity analyses.

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Enclosure to 3-1157 nnr,co to Request for Additional Information Regarding Pilot 10 license Amendment ......".....,.,,,,**

of PRA in Debate Used Vogtle Description unendorsed ire method?

PRA?

Model?

The used) 2 No No in occupied areas No

Enclosure to NL-13-1157 Response to Request for Additional Information Regarding Pilot 10 CFR 50.69 License Amendment Request Table: List of Fire PRA Methods in Debate Fix in Vogtle List of Fire PRA Methods Used in Is this FPRA Base in Debate Vogtle Description unendorsed Case Remarks No. (Source: NEI and NRC fire method? Sensitivity ADAMS ML13094A466) PRA?

Model?

Vogtle fire PRA does

c. Used to justify Non- not credit any incipient Justification needed No No No Abandonment detection Vogtle FPRA looked for the possibility of Yes MCR abandonment on (consis Non-abandonment with Need consistent industry loss of functions. No 4 No tent with No loss of function approach or guidance fire scenarios identified NUREGI in which operators CR 6850) would abandon MCR due to loss of function Need common approach to addressing if screening Vogtle FPRA uses Control room value applies to plant. Does CCDP=1.0 screening 5 abandonment (0.1 CCDP it bound all actions or just No No No value for all MCR screening value) address action at remote abandonment scenrios panel and add on all other actions Vogtle fire PRA did not reduce transient Administrative control 6 No No No ignition frequency frequency reduction based on administrative control E1-4

Enclosure to NL-13-1157 Response to Request for Additional Information Regarding Pilot 10 CFR 50.69 License Amendment Request Table: List of Fire PRA Methods in Debate Fix in Vogtle List of Fire PRA Methods Used in Is this FPRA Base in Debate Vogtle Description unendorsed Case Remarks No. (Source: NEI and NRC fire method? Sensitivity ADAMS ML13094A466) PRA?

Model?

a. FAa 64: includes Technical development credit for significant completed; staff memo No No No None administrative control coming soon

b. Controls for Need common approach or storage/placement value and should consider Yes No No None (HRAIvalue for FAa 64 administrative violation)

Vogtle FPRA assumed Handle separate from FAa uniform transient

64. The suggested method ignition source proposes the use of non

c. Areal factor Yes No No distribution in a uniform transient ignition physical analysis unit source distribution in a which is consistent physical analysis unit (PAU) with NUREG/CR-6850 Generically use lower Vogtle FPRA used HRR for transient Use accepted approach Yes if general lower HRRs in some combustibles (even use HRR appropriate for use of a lower PAUs based on an 7 though higher HRR is area and adjust frequency HRR without Yes No NRC endorsed method possible) to compensate (with justification an endorsed (by June 21, 2012 for perceived lower considering item 6a1b) method basis NRC letter) frequency of occurrence E1-5

to 3-11 Additional Inform it"... nC::.A Amendment nC'I"U.lI=::n Table: of Methods in Debate Fix Methods Is this FPRA Vogtle Description Remarks No.

Model?

8 cable No No induced Yes if counting 9 No No FAQ

to 3-1157 to for Additional Information Regarding Pilot 10 CFR Amendment Request Table: PRA Methods in Debate Fix in Vogtle of Methods Is this FPRA Description unendorsed Remarks (Source: NEI and NRC method?

ML13094A466) PRA?

for some No No

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Enclosure to Nl-13-1157 Response to Request for Additional Information Regarding Pilot 10 CFR 50.69 License Amendment Request Table: List of Fire PRA Methods in Debate l 1st f F* PRA M h d U d " Fix in Vogtle 0 "Ire et 0 s Is this se In FPRA Base In Debate " " Vogtle N0" (S ource.. NEI an d NRC Description unendorsed th d?

f" Ire S Case "t""t Remarks ADAMS Ml13094A466) me a " PRA? ensl IVI y Model?

Not updating generic data U t d h Vogtle F PRA used

'th I t l d t se accep e approac ItT d t 15 ~' , ~ an -speci IC a a update using plant-specific Yes No No pan specllc ,a a (Ignition frequency or d t ' t through Bayesian

,nn, ' re I'la b'I't~\I\

su...,...,resslon lit)' J a a as appropna e ,n'd ate) u..,. ,\

Industry provided - believe is No (but 6850 V tl F PRA d'd

, ,related to crediting flamastic does not og e ,Ire I 16 Credit for cable coatings t I' , t / d f' 'd I No No not credit any cable o e Imina e re uce Ire provi e c ear t'

, coalngs spread gUidance)

Industry provided - believe is No (but 6850 V tl F PRA d'd g

Credit for solid metal related to does not N N °t e d,ltre I'd I

17 , , t' / d ' f' 'd I 0 0 no cre I any so I bottom ca bl e t rays eIImina Ing re uClng Ire provi e c ear t I b tt t

' me a 0 om rays spread to other cable trays gUidance)

Vogtle Fire PRA did 18 Diesel ,generator fire L'Iml'ted use Yes N0 N0 not use diesel '

reduction factor generator fire reduction factor Related to methods with a "

st aff POSI"t'Ion (th aug h dOff I eren t Ensure usmg accepted th an th e ongma ". II th d . approaches as endorsed y au ore b NRC I tt method) y e er Electrical cabinet heat Vogtle Fire PRA used release rate or severity Alternative approaches that electrical cabinet factor 19 factors and cabinet to are developed should have Yes Yes Yes in cabinets in cable cabinet fires (one method phenomenological basis spreading room, 4.16 rejected , one method KV switch gear room E1-8