NL-13-1157, 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 AffairsDirector 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.
v 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......".....,.,,,,**
Description of PRA in Debate unendorsed method?
Used Vogtle ire 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 No.
List of Fire PRA Methods in Debate (Source: NEI and NRC ADAMS ML13094A466)
- c.
Used to justify Non-Abandonment 4
Non-abandonment with loss of function 5
Control room abandonment (0.1 CCDP screening value) 6 Administrative control frequency reduction Description Justification needed Need consistent industry approach or guidance Need common approach to addressing if screening value applies to plant. Does it bound all actions or just address action at remote panel and add on all other actions Is this unendorsed method?
No No No No Used in Vogtle fire PRA?
No Yes (consis tent with NUREGI CR 6850)
No No Fix in Vogtle FPRA Base Case Sensitivity Model?
No No No No Remarks Vogtle fire PRA does not credit any incipient detection Vogtle FPRA looked for the possibility of MCR abandonment on loss of functions. No fire scenarios identified in which operators would abandon MCR due to loss of function Vogtle FPRA uses CCDP=1.0 screening value for all MCR abandonment scenrios Vogtle fire PRA did not reduce transient ignition frequency based on administrative control E1-4
7 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 List of Fire PRA Methods in Debate No.
(Source: NEI and NRC ADAMS ML13094A466)
- a.
FAa 64: includes credit for significant administrative control
- b.
Controls for storage/placement (HRAIvalue for administrative violation)
- c. Areal factor Generically use lower HRR for transient combustibles (even though higher HRR is possible) to compensate for perceived lower frequency of occurrence Description Technical development completed; staff memo coming soon Need common approach or value and should consider FAa 64 Handle separate from FAa
- 64. The suggested method proposes the use of non uniform transient ignition source distribution in a physical analysis unit (PAU)
Use accepted approach use HRR appropriate for area and adjust frequency (with justification considering item 6a1b)
Is this unendorsed method?
No Yes Yes Yes if general use of a lower HRR without an endorsed method basis Used in Vogtle fire PRA?
No No No Yes Fix in Vogtle FPRA Base Case Sensitivity Model?
No No No No Remarks None None Vogtle FPRA assumed uniform transient ignition source distribution in a physical analysis unit which is consistent with NUREG/CR-6850 Vogtle FPRA used lower HRRs in some PAUs based on an NRC endorsed method (by June 21, 2012 NRC letter)
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to 3-11 Additional Inform it"...nC::.A Amendment nC'I"U.lI=::n Table:
of Methods in Debate No.
Methods Description Is this Vogtle Fix FPRA Model?
Remarks 8
cable induced No No 9
Yes if counting FAQ No No
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?
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 f F*
PRA M h d U d "
l 1st 0 "Ire et 0 s Is this se In In Debate Vogtle
. NEI d NRC Description unendorsed f"
N0" (Source.
an th d?
Ire ADAMS Ml13094A466) me a "
PRA?
Not updating generic data U
t d h
'th I t l
d t se accep e approac 15
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, ~ an -speci IC a a update using plant-specific Yes No (Ignition frequency or d t
' t
,nn, I'
b'I't~\\I\\
a a as appropna e su...,...,resslon re la lit)'J Industry provided - believe is No (but 6850
,related to crediting flamastic does not 16 Credit for cable coatings t
I',
t / d f'
'd I
No o e Imina e re uce Ire provi e c ear spread gUidance)
Industry provided - believe is No (but 6850 Credit for solid metal related to does not N
17 I,, t'
/ d f'
'd I
0 bottom ca ble trays e Imina Ing re uClng Ire provi e c ear spread to other cable trays gUidance)
Diesel generator fire L' 't d Y
N 18 Iml e use es 0
reduction factor Related to methods with a "t'
(th h dOff t
Ensure usmg accepted t ff aug I eren s a POSI Ion
". II th d
. approaches as endorsed than the ongma y au ore b NRC I tt method) y e er Electrical cabinet heat release rate or severity Alternative approaches that 19 factors and cabinet to are developed should have Yes Yes cabinet fires (one method phenomenological basis rejected, one method Fix in Vogtle FPRA Base Case S
"t""t ensl IVI y Model?
No No N
0 N0 Yes Remarks Vogtle F PRA used ItT d t pan specllc,a a through Bayesian
,n'd,\\
u..,. ate)
V tl F PRA d'd og e,Ire I
not credit any cable t'
coalngs V
tl F PRA d'd g
°t e d,ltre I'd I
no cre I any so I t I b tt t
me a 0 om rays Vogtle Fire PRA did not use diesel generator fire reduction factor Vogtle Fire PRA used electrical cabinet factor in cabinets in cable spreading room, 4.16 KV switch gear room E1-8