LIC-13-0179, Probabilistic Risk Assessment (PRA) RAI Responses 01.j.04, 01.j.05, and 01.j.06 - NFPA-805 Transition

Probabilistic Risk Assessment (PRA) RAI Responses 01.j.04, 01.j.05, and 01.j.06 - NFPA-805 Transition

ML13353A569
Person / Time
Site:	Fort Calhoun
Issue date:	12/18/2013
From:	Cortopassi L Omaha Public Power District
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LIC-13-0179, TAC ME7244
Download: ML13353A569 (9)

Text

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ilppB Omaha Public Power Olstrfcl 444 South 16h Street Mall Omaha, NE 68102-2247 L1C-13-0179 December 18, 2013 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Fort Calhoun Station, Unit No.1 Renewed Facility Operating License No. DPR-40 NRC Docket No. 50-285

References:

See Pages 3 and 4

SUBJECT:

Probabilistic Risk Assessment (PRA) RAI Responses 01.j.04, 01.j.05, and 01.j.06 - NFPA-805 Transition (ME7244)

Attached is the Omaha Public Power District (OPPD) response to the Nuclear Regulatory Commission (NRC) request for additional information (RAI) (Reference 19) regarding probabilistic risk assessment (PRA) responses 01.j.04, 01.j.05, and 01.j.06. This information is submitted in support of OPPD's license amendment request (LAR) (Reference 1) to adopt NFPA 805, Performance-Based Standard for Fire Protection for Light Water Reactor Generating Plants (2001 Edition). A brief history of correspondence related to this issue is as follows:

The NRC reviewed OPPD's application (Reference 1) as supplemented by References 2 through 4 and determined that additional information was required in order to complete their review.

References 5, 9, 12, 14, 16, and 19 contain NRC requests for additional information regarding the NFPA 805 LAR. OPPD responded to the NRC RAls in References 6, 7, and 8, 10, 11, 13, 15, 17, and 18.

There are no new regulatory commitments being made in this letter because of the enclosed NFPA 805 RAI responses.

Please note that OPPD plans to supplement the NFPA 805 transition LAR, which will reflect the applicable information delineated in the enclosed RAI responses. AR 48249 is tracking the LAR supplement.

In accordance with 10 CFR 50.91, a copy of this letter, without the attachment, is being provided to the designated State of Nebraska official.

If you should have any questions regarding this submittal or require additional information, please contact Mr. Bill R. Hansher, Supervisor-Nuclear Licensing, at 402-533-6894.

Employment with Equal Opportunity

U. S. Nuclear Regulatory Commission LlC-13-0179 Page 2 I declare under penalty of perjury that the foregoing is true and correct.

Executed on December~

Louis P. Cortopassi Site Vice President and CNO LPC/BJV/mle

Attachment:

Response to PRA RAls 01.j.04, 01.j.05, and 01.j.06 c:

M. L. Dapas, NRC Regional Administrator, Region IV J. W. Sebrosky, NRC Senior Project Manager L. E. Wilkins, NRC Project Manager J. C. Kirkland, NRC Senior Resident Inspector Manager Radiation Control Program, Nebraska Health & Human Services, R & L Public Health Assurance, State of Nebraska (w/out attachments)

U. S. Nuclear Regulatory Commission LlC-13-0179 Page 3 Reference List

1. Letter from OPPD (J. A. Reinhart) to NRC (Document Control Desk), License Amendment Request 10-07, Proposed Changes to Adopt NFPA 805, Performance-Based Standard for Fire Protection for Light Water Reactor Generating Plants (2001 Edition) at Fort Calhoun Station, dated September 28, 2011 (LlC-11-0099) (ML112760660)

2. Letter from OPPD (D. J. Bannister) to NRC (Document Control Desk), Supplement to License Amendment Request (LAR) 10-07, Proposed Changes to Adopt NFPA 805, Performance-Based Standard for Fire Protection for Light Water Reactor Generating Plants (2001 Edition) at Fort Calhoun Station, dated December 19, 2011 (ML113540334) (LlC-11-0130)

3. Letter from OPPD (D. J. Bannister) to NRC (Document Control Desk), Clarification of Supplement to License Amendment Request (LAR) 10-07, Proposed Changes to Adopt NFPA 805, Performance-Based Standard for Fire Protection for Light Water Reactor Generating Plants (2001 Edition) at Fort Calhoun Station, dated December 22, 2011 (ML11363A077) (LlC-11-0136)

4. Letter from OPPD (D. J. Bannister) to NRC (Document Control Desk), Submittal of Fire Dynamic Input Files in Response to NRC NFPA 805 Transition License Amendment Request Audit Team Request at Fort Calhoun Station, dated March 20, 2012 (ML12083A147) (LlC 0033)

5. Letter from the NRC (L. E. Wilkins) to OPPD (David J. Bannister), Fort Calhoun Station, Unit No.1 - Request for Additional Information Re: License Amendment Request to Adopt National Fire Protection Agency Standard NFPA 805 (TAC No. ME7244), dated April 26, 2012 (NRC-12-0041) (ML121040048)

6. Letter from OPPD (D. J. Bannister) to NRC (Document Control Desk), Responses to Requests for Additional Information Re: License Amendment Request 10-07 to Adopt NFPA 805, "Performance-Based Standard for Fire Protection for Light Water Reactor Generating Plants," 2001 Edition, at Fort Calhoun Station, dated July 24, 2012 (LlC-12-0083)

(ML12208A131)

7. Letter from OPPD (D. J. Bannister) to NRC (Document Control Desk), Responses to Requests for Additional Information Re: License Amendment Request 10-07 to Adopt NFPA 805, "Performance-Based Standard for Fire Protection for Light Water Reactor Generating Plants," 2001 Edition, at Fort Calhoun Station, dated August 24, 2012 (LlC-12-0120)

(ML12240A151 )

8. Letter from OPPD (L. P. Cortopassi) to NRC (Document Control Desk), Responses to Requests for Additional Information Re: License Amendment Request 10-07 to Adopt NFPA 805, "Performance-Based Standard for Fire Protection for Light Water Reactor Generating Plants," 2001 Edition, at Fort Calhoun Station, September 27, 2012 (LlC-12-0135)

(ML12276A046)

9. Email from NRC (L. E. Wilkins) to OPPD (D. L. Lippy), DRAFT: Fort Calhoun NFPA 805, Second Round (ME7244), dated February 22,2013 (NRC-13-0014)

10. Letter from OPPD (M. J. Prospero) to NRC (Document Control Desk), Responses to Second Request for Additional Information Re: License Amendment Request to Adopt NFPA 805 at Fort Calhoun Station (TAC No. ME7244), dated April 23, 2013 (LlC-13-0033)

11. Letter from OPPD (L. P. Cortopassi) to NRC (Document Control Desk), Remaining Responses to Second Request for Additional Information Re: License Amendment Request to Adopt NFPA 805 at Fort Calhoun Station (TAC No. ME7244), dated May 21,2013 (LlC 0060)

12. Email fromNRC(J.M.Sebrosky)toOPPD(D.L.Lippy).FortCalhounNFPA805.Third Round of RAls (ME7244), dated June 27,2013 (NRC-13-0081)

U. S. Nuclear Regulatory Commission LlC-13-0179 Page 4

13. Letter from OPPD (L. P. Cortopassi) to NRC (Document Control Desk), Responses to Third Request for Additional Information Regarding License Amendment Request to Adopt NFPA 805 at Fort Calhoun Station (TAC No. ME7244), dated July 29,2013 (LlC-13-0096)

14. Email fromNRC(L.E.Wilkins)toOPPD(D.L.LippY).FortCalhounNFPA805.Third Round, Second Part, of RAls (ME7244), dated August 14, 2013 (NRC-13-0102)

15. Letter from OPPD (L. P. Cortopassi) to NRC (Document Control Desk), Safe Shutdown Analysis (SSA) RAI Response - NFPA-805 Transition (ME7244), dated September 12, 2013 (LlC-13-0129)

16. Email from NRC (L. E. Wilkins) to OPPD (M. L. Edwards), Fort Calhoun Fourth Round RAls for NFPA 805 LAR (ME7244), dated September 27,2013 (NRC-13-0130)

17. Letter from OPPD (L. P. Cortopassi) to NRC (Document Control Desk), Probabilistic Risk Assessment (PRA) RAI Response - NFPA-805 Transition (ME7244), dated October 11, 2013 (ML13288A139) (LlC-13-0142)

18. Letter from OPPD (L. P. Cortopassi) to NRC (Document Control Desk), Safe Shutdown Analysis (SSA) RA117.02 Response - NFPA-805 Transition (ME7244), dated November 11, 2013 (LlC-13-0167)

19. Email from NRC (L. E. Wilkins) to OPPD (8. R. Hansher), Fort Calhoun Station RAls Re:

NFPA-805 (ME7244), dated November 15, 2013 (ML13322A020) (NRC-13-0146)

LI C-13-0 179 Attachment Page 1 Omaha Public Power District (OPPD)

Response to PRA RAls 01.j.04, 01.j.05, and 01.j.06 License Amendment Request to Adopt National Fire Protection Association Standard 805 Performance-Based Standard for Fire Protection for Light Water Reactor Generating Plants at Fort Calhoun Station, Unit 1 (TAC No. ME7244)

By letter dated September 28, 2011 [Reference 1] (Agencywide Documents Access and Management System (ADAMS) Accession No. ML112760660), as supplemented by letters dated December 19 and 22, 2011, and March 20, 2012 (ADAMS Accession Nos. ML113540334, ML11363A077, and ML12083A147, [References 2 -

4] respectively), Omaha Public Power District, (the Licensee), submitted a license amendment request (LAR) to transition their fire protection licensing basis at the Fort Calhoun Station, Unit 1, from Title 10 of the Code of Federal Regulations (CFR), Section 50.48(b), to 10CFR50.48(c), National Fire Protection Association Standard NFPA 805 (NFPA 805).

A review team, consisting of U.S. Nuclear Regulatory Commission (NRC) staff and contractors from Pacific Northwest National Laboratory (PNNL) and the Center for Nuclear Waste Regulatory Analyses (CNWRA) participated in a regulatory audit of Fort Calhoun in Blair, NE from March 5 -9, 2012. By letter dated April 26, 2012, [Reference 5] (ADAMs Accession No. ML12198A406) the NRC issued requests for additional information (RAls).

By letters dated July 24, 2012 [Reference 6]

(ADAMs Accession No. ML12208A131), August 24, 2012 [Reference 7] (ADAMs Accession No. ML12240A151), and September 27,2012 [Reference 8] (ADAMS Accession No. ML12276A046) the licensee provided responses to the RAls. The NRC staff reviewed the information provided by the licensee in response to the first set of RAls and determined that additional information was needed for the staff to complete its evaluation. Consequently, the staff issued additional RAls on February 22,2013, [Reference 9] (ADAMS Accession No. ML13053A226), June 27, 2013

[Reference 12] (ADAMS Accession No. ML13178A035), August 14, 2013 [Reference 14]

(ADAMS Accession No. ML13226A122) and September 27, 2013 [Reference 16] (ADAMS Accession No. ML13270A287). The licensee responded to these RAls in letters dated April 23, 2013 [Reference 10] (ADAMS Accession No. ML13116A015), May 21, 2013 [Reference 11]

(ADAMS Accession No. ML13144A814), July 29, 2013 [Reference 13] (ADAMS Accession No. ML13211A055), September 12, 2013 [Reference 15], October 11, 2013 [Reference 17] (ADAMS Accession No. ML13288A139), and November 11,2013 [Reference 18].

The U.S. NRC staff has reviewed the information provided in your application and determined that additional information is required in order to complete its review. These RAls can be found below. Please contact me if a clarifying call is needed.

LlC-13-0179 Attachment Page 2 Probabilistic Risk Assessment (PRA) Request for Additional Information (RAI) 01.j.04 By "LIC-13-0142, Probabilistic Risk Assessment (PRA) RAI Response - [[NFPA" contains a listed "[" character as part of the property label and has therefore been classified as invalid. Transition|letter dated October 11, 2013]] (ADAMS Accession No. ML13288A139) the licensee responded to PRA RAI 01.j.02 and provided a summary description of the Human Reliability Analysis (HRA) process leading to a Human Error Probability (HEP) of 0.015 for main control room (MCR) abandonment.

The conditional core damage probability (CCDP) for MCR abandonment includes the equipment unreliability and is 0.141. It appears from the licensee's response that this single value is used for every MCR abandonment scenario.

a. If any values other than 0.141 are used as the CCDP, (e.g., 1.0) please provide the other values, a characterization of the scenarios where these values are used, and a summary of how each value is developed. This information should include explanations of how the following scenarios i, ii, and iii are addressed. A method based on these scenarios is discussed in the Safety Evaluation for the Duane Arnold Energy Center, Amendment No. 286, issued on September 10, 2013 (ADAMS Accession No. ML13210A449).

i. Scenarios where the fire fails few functions aside from MCR habitability and successful shutdown is straightforward.

ii. Scenarios where the fire could cause some recoverable functional failures or spurious operations that complicate the shutdown but successful shutdown is likely.

iii. Scenarios where the fire induced failures cause great difficulty for shutdown by failing multiple functions and/or causing complex spurious operations that make successful shutdown unlikely.

b. If no values other than 0.141 are used, please explain how scenarios characterized under a.i, a.ii, and a.iii above are included in the MCR abandonment evaluations.

Evaluate the impact of any changes to the MCR abandonment evaluation as part of the aggregate change in risk requested in PRA RAI 24. If the result of any change is negligible with respect to your current CDF/LERF/delta CDF/delta LERF estimates in PRA RAI 24, a qualitative evaluation would be consistent with RG 1.174 guidelines.

OPPD Response to PRA 01.j.04a.

That is correct; the single value for CCDP discussed in response to PRA RAI 01.j.02 was applied to all scenarios leading to MCR abandonment due to loss of habitability.

In response to the current PRA RAI 01.j.04, the analysis was revised such that each main control room fire scenario with the potential to cause abandonment due to loss of habitability was assigned to one of the following three bins:

Bin 1: Scenarios where the fire fails few functions aside from control room habitability and successful shutdown from outside the control room is straightforward.

Bin 2: Scenarios where the fire could cause some recoverable functional failures or spurious operations that complicate shutdown, but where successful shutdown remains likely.

lIC-13-0179 Attachment Page 3 Bin 3: Scenarios where fire-induced failures cause great difficulty by failing multiple functions and/or complex spurious operations that make shutdown from outside the control room unlikely.

Bin 2 was assigned the CCDP developed in response to PRA RAI 01.j.01 (i.e., 0.141). This CCDP includes contribution from both human and equipment failures. The plant impact associated with this bin is considered most representative of the abandonment scenarios to which the alternate shutdown process is designed, proceduralized, and trained upon.

For Bin 1, the CCDP was recalculated assuming that the emergency diesel generator is not required for successful shutdown (Le., where offsite power is not failed by the fire). Fire scenarios assigned to this bin were verified to not fail offsite power. The need for auxiliary feedwater, charging, and the remaining modeled functions are retained in this CCDP calculation. The human error contribution was unmodified from Bin 2.

This resulted in a CCDP of 0.0749, considering both human and equipment failures. This value was conservatively rounded up to a Bin 1 CCDP of 0.10.

Bin 3 was assigned a CCDP of 1.0. A hypothetical example of a Bin 3 fire scenario might be one involving spurious operation of multiple components, leading to a LOCA beyond the RCS makeup capability available at the alternate shutdown panel.

The Bin 1, 2, and 3 CLERP values are assumed equivalent to the CCDP values (Le., 0.10, 0.141, and 1.0, respectively) since the alternate shutdown process does not include provision for containment isolation.

Note that containment isolation may occur automatically following control room abandonment, but this plant response has not been explicitly evaluated.

The main control room analysis used for the composite sensitivity study response to PRA RAI 24 was updated to incorporate the above binning approach. The following table summarizes the total plant CDF, total plant LERF, VFDR ~CDF, and VFDR ~LERF for the base fire PRA (Reference 1) and for the composite sensitivity study (PRA RAI 24) modified to include the above binning approach.

Base Fire PRA Composite (Reference 1 -

Sensitivity Study ML112760660)

(PRA RAI 24) + MCR Abandonment Binning Approach Net VFDR ACDF for NFPA S.72E-06 6.07E-06 805 Transition (/yr)

Net VFDR ALERF for NFPA 6.67E-07 8.62E-07 805 Transition (/yr)

Total CDF (internal, flood, 6.01 E-OS 9.99E-OS fire) (/yr)

Total LERF (internal, flood, 4.82E-06 8.S8E-06 fire) (/yr)

LlC-13-0179 Attachment Page 4 In conclusion, the total CDF, total LERF, VFDR flCDF, and VFDR flLERF remain within RG 1.174 Revision 1 Region II using the fire PRA model supporting the composite sensitivity study response to PRA RAI 24, modified to include the above binning approach for MCR abandonment scenarios. The binning approach only slightly increased the risk metrics reported in response to PRA RAI 24, and the conclusions of the PRA RAI 24 response remain valid.

OPPD Response to PRA 01.j.04b.

The analysis was revised in response to Part 'a' to eliminate the use of a single CCDP value applied to all scenarios leading to MCR abandonment due to loss of habitability.

PRA RAI 01.j.05 With respect to the main control room abandonment human error probability (HEP) of 0.015 cited in PRA RAI 01.j.04 above, the licensee in its response to PRA RAI 01.j.01.a.iv dated May 21, 2013 (ADAMS Accession No. Ml13144A814) stated that the abandonment probability is the result of "more of a bounding approach." An HEP of 0.015 is too small for a bounding approach according to the scoping fire HRA quantification approach (chapter 5.2) of NUREG-1921, "EPRIINRC-RES Fire Human Reliability Analysis Guidelines -

Final Report".

The licensee has not described the analysis in detailed enough terms for the NRC staff to do a detailed review. Given NRC's observation about the low value estimated for the HEP for MCR abandonment, please provide assurance that the HRA for MCR abandonment will be included as a part of the fire HRA focused scope peer review and upgrade to be completed prior to self approval, as identified in the response to PRA RAI 23.01 dated October 11, 2013 (ADAMS Accession No. Ml13288A139).

OPPD Response to PRA 01.j.05 The OPPD human reliability analysis of plant shutdown following main control abandonment due to loss of habitability will be included within the scope of the focused-scope peer review committed to via the response to PRA RAI 23.01.

PRA RAI 01.j.06 In a "LIC-13-0142, Probabilistic Risk Assessment (PRA) RAI Response - [[NFPA" contains a listed "[" character as part of the property label and has therefore been classified as invalid. Transition|letter dated October 11, 2013]], (ADAMS Accession No. Ml13288A 139) the licensee responded to PRA RAI 01.j.02. Part b of that response referred to the loss of a key safety function, as opposed to loss of habitability, as a condition necessitating abandonment.

However, RAI 01.j.02 issued on August 14, 2013, (ADAMS Accession No. Ml13226A 122) refers to abandonment due only to loss of habitability and implies that loss of control would be assigned a CCDP of 1.0. Given the licensee's response to PRA RAI 01.i.02 in the October 11 letter that no credit will be taken for the CCDP for loss of control, please clarify whether the discussions on timing in the response to PRA RAI 01.j.02 apply to loss of habitability only.

OPPD Response to PRA 01.j.06 In response to PRA RAI 01.j.02 Part b, reference to main control room abandonment following loss of a key safety function was unnecessary. Consistent with the response to PRA RAI 01.i.02, the FCS

LlC-13-0179 Attachment Page 5 fire PRA does not credit alternate shutdown to mitigate fires that require abandonment due to loss of plant control. The fire PRA credits alternate shutdown only to mitigate fires that require abandonment due to loss of habitability.