Text

Response to NRC Request for Additional Information Regarding the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plan
	ML14363A057
Person / Time
Site:	Browns Ferry
Issue date:	12/17/2014
From:	James Shea; Tennessee Valley Authority
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	CNL-14-208, TAC MF1185, TAC MF1186, TAC MF1187
	Download: ML14363A057 (291)
	v • d • e

Security-Related Information - Withhold from Public Disclosure in accordance with 10 CFR 2.390.

Enclosure 7 of this letter contains Security-Related Information.

Upon removal of Enclosure 7, this letter is uncontrolled.

Enclosure 7 has been removed (ce 12.18.214)

L44 141217 001 1101 Market Street, Chattanooga, Tennessee 37402 CNL-14-208 December 17, 2014 10 CFR 50.90 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Browns Ferry Nuclear Plant, Units 1, 2, and 3 Renewed Facility Operating License Nos. DPR-33, DPR-52, and DPR-68 NRC Docket Nos. 50-259, 50-260, and 50-296

Subject:

Response to NRC Request for Additional Information Regarding the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos.

MF1185, MF1186, and MF1187) - Probabilistic Risk Assessment Follow Up (162-Day Responses)

References:

1. Letter from TVA to NRC, "License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants (2001 Edition) (Technical Specification Change TS-480)," dated March 27, 2013 (ADAMS Accession No. ML13092A393)

2. Letter from TVA to NRC, "Response to NRC Request to Supplement License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187)," dated May 16, 2013 (ADAMS Accession No. ML13141A291)

3. Letter from NRC to TVA, "Browns Ferry Nuclear Plant, Units 1, 2, and 3 -

Request for Additional Information Regarding License Amendment Request to Adopt National Fire Protection Association Standard 805 Performance-Based Standard for Fire Protection for Light Water Reactor Generating Plants (TAC Nos. MF1185, MF1186, and MF1187)," dated November 19, 2013 (ADAMS Accession No. ML13298A702)

U.S. Nuclear Regulatory Commission CNL-14-208 Page 2 December 17, 2014

4. Letter from TVA to NRC, "Response to NRC Request for Additional Information Regarding the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187) - Set 1," dated December 20, 2013 (ADAMS Accession No. ML13361A093)

5. Letter from TVA to NRC, "Response to NRC Request for Additional Information Regarding the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187) - Set 2," dated January 10, 2014 (ADAMS Accession No. ML1401A088)

6. Letter from TVA to NRC, "Response to NRC Request for Additional Information Regarding the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187) - Set 3," dated January 14, 2014 (ADAMS Accession No. ML14077A201)

7. Letter from TVA to NRC, "Response to NRC Request for Additional Information Regarding the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187) - Set 4," dated February 13, 2014 (ADAMS Accession No. ML14055A305)

8. Letter from TVA to NRC, "Response to NRC Request for Additional Information Regarding the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187) - Set 5,"

dated March 14, 2014 (ADAMS Accession No. ML14079A159)

9. Letter from NRC to TVA, "Browns Ferry Nuclear Plant, Units 1, 2, and 3 -

Request for Additional Information Regarding Attachment X of License Amendment Request to Adopt National Fire Protection Association Standard 805, Performance-Based Standard for Fire Protection for Light Water Reactor Generating Plants (TAC Nos. MF1185, MF1186, and MF1187),"

dated May 20, 2014 (ADAMS Accession No. ML14126A388)

10. Letter from TVA to NRC, "Update to the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187),"

dated May 30, 2014 (ADAMS Accession No. ML14154A496)

U.S. Nuclear Regulatory Commission CNL-14-208 Page 3 December 17, 2014

11. Letter from NRC to TVA, "Browns Ferry Nuclear Plant, Units 1, 2, and 3 -

Request for Additional Information Regarding License Amendment Request to Adopt National Fire Protection Association Standard 805, Performance-Based Standard for Fire Protection for Light Water Reactor Generating Plants (TAC Nos. MF1185, MF1186, and MF1187)," dated May 21, 2014 (ADAMS Accession No. ML14133A526)

12. Letter from TVA to NRC, "Response to NRC Request for Additional Information Regarding the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187) - Attachment X and Fire Modeling," dated June 13, 2014 (ADAMS Accession No. ML14167A175)

13. Letter from NRC to TVA, "Summary of June 26, 2014 Meeting with Tennessee Valley Authority Regarding License Amendment Request to Adopt National Fire Protection Association Standard 805 for Browns Ferry Nuclear Plant Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187,"

dated July 29, 2014 (ADAMS Accession No. ML14183B546)

14. Letter from TVA to NRC, "Response to the Nuclear Regulatory Commission's (NRC) Request for Additional Information Regarding the License Amendment Request to Adopt National Fire Protection Association 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187)-Attachment X (second set)," dated July 10, 2014 (ADAMS Accession No. ML14192B044)

15. Letter from NRC to TVA, "Browns Ferry Nuclear Plant, Units 1, 2, and 3 -

Request for Additional Information Regarding License Amendment Request to Adopt National Fire Protection Association Standard 805, Performance-Based Standard for Fire Protection for Light Water Reactor Generating Plants (TAC Nos. MF1185, MF1186, and MF1187)," dated July 31, 2014 (ADAMS Accession No. ML14203A125)

16. Letter from TVA to NRC, "Response to NRC Request for Additional Information Regarding the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187) - Probabilistic Risk Assessment Follow Up (60-Day Responses)," dated August 29, 2014 (ADAMS Accession No. ML14248A291)

17. Letter from TVA to NRC, "Update to the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187)" dated September 16, 2014 (ADAMS Accession No. ML14260A324)

U.S. Nuclear Regulatory Commission CNL-14-208 Page 4 December 17, 2014

18. Letter from TVA to NRC, "Response to NRC Request for Additional Information Regarding the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187) - Probabilistic Risk Assessment Follow Up (90-Day Responses)," dated October 6, 2014 (ADAMS Accession No. ML14281A154)

19. Electronic Mail from F. Saba (NRC) to G. Williams (TVA) and C. Szabo (TVA), "Round 2 RAIs regarding NFPA 805 Attachment X for Browns Ferry Plant (MF1185, MF1186, and MF1187)," dated November 19, 2014 By letter dated March 27, 2013 (Reference 1), the Tennessee Valley Authority (TVA) submitted a license amendment request (LAR) for Browns Ferry Nuclear Plant (BFN), Units 1, 2, and 3, to transition to National Fire Protection Association Standard (NFPA) 805. In addition, by letter dated May 16, 2013 (Reference 2), TVA provided information to supplement the Reference 1 letter.

By letter dated November 19, 2013 (Reference 3), the NRC staff requested additional information to support the review of the LAR. By letters dated December 20, 2013, January 10, 2014, January 14, 2014, February 13, 2014, and March 14, 2014 (References 4, 5, 6, 7, and 8, respectively), TVA responded to the NRC staff's request for additional information (RAI).

By letter dated May 20, 2014 (Reference 9), the NRC staff requested additional information to support the review of the LAR, Attachment X, "Elimination of Containment Accident Pressure."

TVA responded to the NRC staff's RAI by letters dated June 13, 2014, and July 10, 2014 (References 12 and 14, respectively).

By letter dated May 21, 2014 (Reference 11), the NRC staff provided a follow-up RAI specific to fire modeling. TVA responded to the NRC staff's RAI in the above letter dated June 13, 2014 (Reference 12).

By letter dated July 31, 2014 (Reference 14), the NRC provided a follow-up RAI specific to the probabilistic risk assessment. The required due dates for responding to the RAI varied from 60 days to 162 days. By letters dated August 29, 2014 (Reference 16) and October 6, 2014 (Reference 18), TVA responded to the NRCs 60-day and 90-day RAIs, respectively.

By letters dated May 30, 2014, and September 16, 2014, (References 10 and 17, respectively)

TVA provided updates to the LAR. of this submittal provides the third set of TVA responses to the final set of RAIs identified in the July 31, 2014 (Reference 15) letter. As stated in the Reference 15 letter, these responses are nominal 162-day responses and are due by December 17, 2014. Enclosure 1 also provides responses to the second round RAIs, related to References 12 and 14, identified in the Reference 19 electronic mail. Enclosure 2 provides a listing of all RAls listed in the Reference 15 letter and the Reference 19 electronic mail with the actual date of the TVA response to each RAI.

U.S. Nuclear Regulatory Commission CNL-14-208 Page 5 December 17, 2014 As discussed during the public meeting between TVA and the NRC on June 26, 2014 (Reference 13), several Fire Probabilistic Risk Assessment (PRA) updates have been incorporated. These updates include an update to the Fire PRA model with the latest revision of the BFN Internal Events model , inclusion of changes related to TVA responses to RAis, fire modeling enhancements and other model refinements. Changes to human reliability analysis (HRA) dependencies for fire and non-fire events were included based on TVA responses to RAis. Other model refinements included fire modeling analysis updates based on new guidance and refinement of conservative full-room burn scenarios. In addition , the Main Control Room Abandonment fault tree modeling was refined . As a result of the these changes, there are reductions in Variances from Deterministic Requirements , changes in the scope of modifications needed, and better sensitivity results. provides updated TVA responses, consistent with the incorporated PRA updates, to RAis that were previously responded to in the Reference 4 through Reference 8, 12, and 18 letters, and changes to information provided in the References 10 and 17 letters. Changes to the responses are denoted by deleted text struck through , inserted text underlined and in bold ,

and a revision bar in the right margin . Enclosure 4 provides descriptions of changes made to the Reference 1 submittal, as supplemented by Reference 2, that are not related to TVA responses to RAis. Enclosure 5 provides a matrix denoting the changes made on each of the affected Reference 1 submittal Enclosure pages, as supplemented by Reference 2. Enclosure 6 provides markups of Reference 1 submittal Enclosure pages, as supplemented by Reference 2, that are classified as non security-related . Enclosure 7 provides markups of Reference 1 submittal Enclosure pages, as supplemented by Reference 2, that are classified as security-related. Enclosure 7 contains security-related information and should be withheld from public disclosure under 10 CFR 2.390.

Consistent with the standards set forth in Title 10 of the Code of Federal Regulations (1 0 CFR),

Part 50.92(c), TVA has determined that the additional information, as provided in this letter, does not affect the no significant hazards consideration associated with the proposed application previously provided in Reference 1.

There are no new regulatory commitments contained in this submittal. Please address any questions regarding this submittal to Mr. Edward D. Schrull at (423) 751-3850.

I declare under penalty of perjury that the foregoing is true and correct. Executed on this 17th day of December 2014.

. tiea 6L cc: See Page 6

U.S. Nuclear Regulatory Commission CNL-14-208 Page 6 December 17, 2014

Enclosures:

1. TVA Response to NRC Request for Additional Information: PRA Follow-Up RAIs (162-day) and SCVB Second Round RAIs

2. Summary of BFN NFPA 805 PRA Follow-Up RAI Response Dates

3. Updated TVA Response to Requests for Additional Information and Previously Submitted Update Letters

4. Description of Additional Changes Made to the Licensing Amendment Request

5. Matrix of Changes Made on Affected License Amendment Request Pages

6. Markups of License Amendment Pages - Non Security-Related

7. Markups of License Amendment Pages - Security-Related cc (Enclosure):

NRC Regional Administrator - Region II NRC Senior Resident Inspector - Browns Ferry Nuclear Plant NRC Project Manager - Browns Ferry Nuclear Plant State Health Officer, Alabama State Department of Health

ENCLOSURE 1 Tennessee Valley Authority Browns Ferry Nuclear Plant, Units 1, 2, and 3 TVA Response to NRC Request for Additional Information: PRA Follow-Up RAIs (162-day) and SCVB Second Round RAIs Probabilistic Risk Assessment (PRA) Request for Additional Information (RAI) 19.a.01 In the letter dated January 10, 2014, the licensee responded to PRA RAI 19.a summing those individual fire area delta risk values in LAR Attachment W that are positive and those that are negative as a means to obtain the total risk increase and decrease, respectively; however, these reported risk totals do not separate the total risk increase associated with all VFDRs retained in the post-transition plant from the total risk decrease (or offset) associated with risk-reduction modifications (e.g., the emergency high pressure makeup pump). Regulatory Guide (RG) 1.17 4 "An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis," Revision 2, May 2011 (ADAMS Accession No. ML100910006) states that combined change request (i.e., those that combine risk increases with risk decreases) should report the risk increases and risk decreases separately.

Provide an estimate of the risk increase from the retained VFDRs and, separately, the risk decrease associated with modifications made only to reduce risk.

RESPONSE

An estimate of the risk increase from the retained Variances from Deterministic Requirements (VFDRs) is shown in Table 1.

Table 1 - Risk Increase from VFDRs Increase in Core Damage Increase in Large Early Unit Frequency (CDF) Release Frequency (LERF)

Unit 1 2.36E-05 2.42E-06 Unit 2 3.29E-05 3.09E-06 Unit 3 3.19E-05 2.86E-06 An estimate of the risk decrease from modifications made only to decrease risk is shown in Table 2.

Table 2 - Fire Risk Decrease from Modifications Unit Decrease in CDF Decrease in LERF Unit 1 1.63E-04 2.48E-05 Unit 2 1.43E-04 2.13E-05 Unit 3 1.53E-04 2.15E-05 The TVA response to PRA RAI 19.b.01.c, in this enclosure, provides a summary of the risk increases and decreases including the total plant fire risk.

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PRA RAI 19.b.01.c In the letter dated February 13, 2014, the licensees response to PRA RAI 19.b and as clarified by the BFN Fire Risk Evaluation report, the top risk-significant fire scenarios for the compliant plant in Fire Area 03-03 for Units 1, 2 and 3 are associated with junction box (discussed in the response to PRA RAI 01.r.01) and cable (discussed in the response PRA RAI 17.d) fires. A review of the BFN Fire Risk Evaluation report confirms that similar scenarios, including self-ignited cable fires and cable fires due to welding and cutting, dominate the risk results of other fire areas, presumably because some of these fires are leading to full room burnout.

However, as noted in FAQs 13-0005, "Cable Fires Special Cases: Self-Ignited and Caused by Welding and Cutting," and 13-0006 past experimentation and operating experience indicate that the impact of such fires is limited such that only the tray or box of initiation may be assumed as the zone of influence. Other examples of apparently conservative modeling techniques include the assumed failure for all fire scenarios of some components whose cables are not routed (as discussed in the response to PRA RAI 11.a and RAI SSA 14). When introduced into the compliant plant, such conservatisms may produce non-conservative estimates of delta risk because risk-reduction modifications that reduce the risk of scenarios with conservatively high risk estimates will overestimate the magnitude of the actual risk reduction that will be achieved.

c. Provide quantitative results (i.e., core damage frequency (CDF), large early release frequency (LERF), change in Delta(¨) CDF, and ¨LERF values) of an assessment that demonstrate that the magnitude of the risk reduction from the improvements being implemented to reduce risk is greater than the magnitude of the risk of the retained VFDRs.

This assessment should explicitly investigate and account for any overestimation in risk associated with conservative assumptions in scenarios that dominate the compliant plant risk but that are greatly reduced by proposed modifications. The impact of the assumption on the additional risk of recovery actions should also be addressed.

RESPONSE

TVA performed the assessment demonstrating that the magnitude of risk reduction from the improvements being implemented to reduce risk is greater than the magnitude of the risk of the retained VFDRs by including credit for the modifications in the compliant plant and quantifying the results. The resulting CDF and LERF were subtracted from the post-transition model results, determining the magnitude of the risk increase from the retained VFDRs. The magnitude of risk reduction from the improvements being made was calculated by subtracting the CDF and LERF of the compliant plant with modifications to reduce risk from the CDF and LERF of the compliant plant without modifications made to reduce risk. Quantitative results of the assessment that demonstrates that the magnitude of the risk reduction from the improvements being implemented to reduce risk is greater than the magnitude of the risk of the retained VFDRs are provided in Tables 1, 2, and 3. Table 1 shows the risk of retained VFDRs.

Table 2 shows the magnitude of risk reduction from the improvements being made. Table 3 shows the total change in fire risk.

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Table 1 - Risk of Retained VFDRs1 Risk or Retained VFDRs

(¨CDF or ¨LERF)

Compliant with Post-Transition -

Post Transition Modifications Compliant with Unit / Metric (CDF or LERF) (CDF or LERF) Modifications Unit 1 CDF 5.03E-05 2.67E-05 2.36E-05 Unit 1 LERF 5.47E-06 3.05E-06 2.42E-06 Unit 2 CDF 5.64E-05 2.35E-05 3.29E-05 Unit 2 LERF 5.37E-06 2.28E-06 3.09E-06 Unit 3 CDF 5.92E-05 2.73E-05 3.19E-05 Unit 3 LERF 5.02E-06 2.17E-06 2.86E-06 Table 2 - Risk of Improvements1 Magnitude of Risk from Modifications

(¨CDF or ¨LERF)

Compliant Without Compliant Without Compliant with Modifications -

Modifications Modifications Compliant with Unit / Metric (CDF or LERF) (CDF or LERF) Modifications Unit 1 CDF 1.89E-04 2.67E-05 1.63E-04 Unit 1 LERF 2.78E-05 3.05E-06 2.48E-05 Unit 2 CDF 1.67E-04 2.35E-05 1.43E-04 Unit 2 LERF 2.35E-05 2.28E-06 2.13E-05 Unit 3 CDF 1.80E-04 2.73E-05 1.53E-04 Unit 3 LERF 2.36E-05 2.17E-06 2.15E-05 Table 3 - Total Fire Delta Risk1 Total Change in Fire Risk

(¨CDF or ¨LERF)

Risk Reduction from Risk of Retained Risk Reduction from Modifications VFDRs Modifications + Risk Unit / Metric (¨CDF or ¨LERF) (¨CDF or ¨LERF) of Retained VFDRs Unit 1 CDF -1.63E-04 2.36E-05 -1.39E-04 Unit 1 LERF -2.48E-05 2.42E-06 -2.24E-05 Unit 2 CDF -1.43E-04 3.29E-05 -1.10E-04 Unit 2 LERF -2.13E-05 3.09E-06 -1.82E-05 Unit 3 CDF -1.53E-04 3.19E-05 -1.21E-04 Unit 3 LERF -2.15E-05 2.86E-06 -1.86E-05 Note 1: Actual calculations may carry more digits than shown in each table, and may result in minor rounding errors when adding or subtracting these values.

Crediting the modifications in the compliant plant eliminates potential dominant conservative assumptions that may overestimate the compliant plant risk. This assessment shows that the total change in CDF and LERF is a risk improvement despite the risk increase from the retained VFDRs. This assessment does not affect the calculation of the additional risk of recovery actions, because the additional risk of recovery actions is determined by setting the recovery actions not to fail in the post transition model, quantifying, and subtracting the resulting CDF and LERF from the post-transition values.

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PRA RAI 24.a Section 2.4.3.3 of the NFPA 805 standard incorporated by reference into Title 10 of Code of Federal Regulations (10 CFR) Section 50.48(c) "Fire Protection - Part 50: Domestic Licensing of Production And Utilization Facilities - Code of Federal Regulations - Title 10: Energy," states that the probabilistic safety assessment (PSA) (PSA is also referred to as PRA) approach, methods, and data shall be acceptable to the authority having jurisdiction, which is the NRC.

RG 1.205, "Risk-Informed, Performance-Based Fire Protection for Existing Light-Water Nuclear Power Plants," identifies NUREG/CR-6850, NEI [Nuclear Energy Institute] 04-02, Revision 2, "Guidance for Implementing a Risk-Informed, Performance-Based Fire Protection Program Under 10 CFR 50.48(c)," and the ongoing FAQ process as documenting approaches, methods, and data acceptable to the staff for adopting a fire protection program consistent with NFPA 805.

The NRC staff identified several methods and weaknesses that were used in the Fire PRA.

RAIs were provided about these methods and weaknesses, and the responses have been reviewed. The staff noted that the justification provided for the methods and weaknesses listed below is not complete.

Methods and weaknesses:

x PRA RAI 01.f regarding the frequency of MCB scenarios x PRA RAI 01.h.ii regarding the frequency and severity factor of catastrophic turbine generator fires x PRA RAI 01.o regarding treatment of dependency for LERF-related HFEs x PRA RAI 01.r (as clarified by PRA RAI 01.r.01) regarding treatment of junction box fires x PRA RAI 01.s regarding use of quantitative screening criteria consistent with CC-II of SR QNS-C1 as clarified by RG 1.200, Revision 2 x PRA RAI 01.v regarding use of minimum joint HEPs x PRA RAI 10 regarding removal of credit for area-wide incipient detection in the auxiliary instrument rooms x PRA RAI 12 regarding scenario-specific timing for emergency depressurization dependent on both fire-induced and random failures x PRA RAI 20 (as clarified by PRA RAI 20.01) regarding credit for existing, non-fire-specific operator actions in the compliant plant x PRA RAI 22.01 regarding estimation of circuit failure probabilities The following Fire Modeling RAI appears to have caused changes that may impact the fire-affected components for a variety of fires. The aggregate change-in-risk evaluation should include the potential impact of changes in:

x FM RAI 01.g regarding treatment of cable spreading room oil spill fires E1-4

The following Fire Protection Engineering RAI appears to have caused changes that may impact risk results. The aggregate change-in-risk evaluation should include the potential impact of changes in:

x FPE RAI 05 regarding the risk treatment of electrical raceway fire barrier The following methods and weaknesses have been identified, but the NRC staff review is continuing with additional RAIs and further supporting information has been requested.

Alternatively, the licensee may replace any of these methods and weaknesses with another method by modifying the Fire PRA model.

Methods and weaknesses still under review:

x PRA RAI 04.01 regarding the credit for MCR abandonment due to loss of control x PRA RAI 04.k.01 regarding dependencies between alternate shutdown actions x PRA RAI 04.l.01 regarding the modeling of random failure probabilities for the backup control panel shutdown path x PRA RAI 10.c.01 regarding the unavailability and unreliability value applied to the total flooding, clean agent suppression system in the cable spreading room x PRA RAI 19.b.01 regarding the apparent dominance of risk scenarios from normally, relatively benign ignition sources (e.g., junction boxes)

The following methods and weaknesses have been identified for which the NRC staff review is continuing with additional Fire Modeling RAIs that may cause changes that impact the fire-affected components for a variety of fires:

x FM RAI 01.01 regarding fire propagation in cable trays x FM RAI 02.01 regarding the damage delay time for cables in covered trays

a. Provide the results of a composite analysis that shows the integrated impact on the fire risk (CDF, LERF, ¨CDF, ¨LERF) after replacing all the identified methods and weaknesses. As the review process is concluded, additional changes to replace any method or weakness still under review may be required. In this composite analysis, for those cases where the individual issues have a synergistic impact on the results, a simultaneous analysis must be performed. For those cases where no synergy exists, a one-at-a-time analysis may be done. If the impact on the change in risk from transition is negligible, a quantitative evaluation is unnecessary.

RESPONSE

The results of a composite analysis that shows the integrated impact on the fire risk (CDF, LERF, CDF, LERF) after replacing all the identified methods and weaknesses, with the exception of those retained in the Fire PRA as described in the revised TVA responses to PRA RAI 24, Parts b and d (see Enclosure 3), is provided in the updated LAR Attachment W (in Enclosure 7 of this letter). The total plant CDF and LERF is provided in LAR Attachment W, Table W-1, and the Fire Area Total CDF and LERF and Total CDF, LERF are provided in LAR Attachment W, Table W-8 for Unit 1, Table W-9 for Unit 2, and Table W-10 for Unit 3.

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Marked up pages showing the changes to LAR Attachment W are provided in Enclosure 7 of this letter.

E1-6

PRA RAI 24.c Section 2.4.3.3 of the NFPA 805 standard incorporated by reference into Title 10 of Code of Federal Regulations (10 CFR) Section 50.48(c) "Fire Protection - Part 50: Domestic Licensing of Production And Utilization Facilities - Code of Federal Regulations - Title 10: Energy," states that the probabilistic safety assessment (PSA) (PSA is also referred to as PRA) approach, methods, and data shall be acceptable to the authority having jurisdiction, which is the NRC.

RG 1.205, "Risk-Informed, Performance-Based Fire Protection for Existing Light-Water Nuclear Power Plants," identifies NUREG/CR-6850, NEI [Nuclear Energy Institute] 04-02, Revision 2, "Guidance for Implementing a Risk-Informed, Performance-Based Fire Protection Program Under 10 CFR 50.48(c)," and the ongoing FAQ process as documenting approaches, methods, and data acceptable to the staff for adopting a fire protection program consistent with NFPA 805.

The NRC staff identified several methods and weaknesses that were used in the Fire PRA.

RAIs were provided about these methods and weaknesses, and the responses have been reviewed. The staff noted that the justification provided for the methods and weaknesses listed below is not complete.

Methods and weaknesses:

x PRA RAI 01.f regarding the frequency of MCB scenarios x PRA RAI 01.h.ii regarding the frequency and severity factor of catastrophic turbine generator fires x PRA RAI 01.o regarding treatment of dependency for LERF-related HFEs x PRA RAI 01.r (as clarified by PRA RAI 01.r.01) regarding treatment of junction box fires x PRA RAI 01.s regarding use of quantitative screening criteria consistent with CC-II of SR QNS-C1 as clarified by RG 1.200, Revision 2 x PRA RAI 01.v regarding use of minimum joint HEPs x PRA RAI 10 regarding removal of credit for area-wide incipient detection in the auxiliary instrument rooms x PRA RAI 12 regarding scenario-specific timing for emergency depressurization dependent on both fire-induced and random failures x PRA RAI 20 (as clarified by PRA RAI 20.01) regarding credit for existing, non-fire-specific operator actions in the compliant plant x PRA RAI 22.01 regarding estimation of circuit failure probabilities The following Fire Modeling RAI appears to have caused changes that may impact the fire-affected components for a variety of fires. The aggregate change-in-risk evaluation should include the potential impact of changes in:

x FM RAI 01.g regarding treatment of cable spreading room oil spill fires E1-7

The following Fire Protection Engineering RAI appears to have caused changes that may impact risk results. The aggregate change-in-risk evaluation should include the potential impact of changes in:

x FPE RAI 05 regarding the risk treatment of electrical raceway fire barrier The following methods and weaknesses have been identified, but the NRC staff review is continuing with additional RAIs and further supporting information has been requested.

Alternatively, the licensee may replace any of these methods and weaknesses with another method by modifying the Fire PRA model.

Methods and weaknesses still under review:

x PRA RAI 04.01 regarding the credit for MCR abandonment due to loss of control x PRA RAI 04.k.01 regarding dependencies between alternate shutdown actions x PRA RAI 04.l.01 regarding the modeling of random failure probabilities for the backup control panel shutdown path x PRA RAI 10.c.01 regarding the unavailability and unreliability value applied to the total flooding, clean agent suppression system in the cable spreading room x PRA RAI 19.b.01 regarding the apparent dominance of risk scenarios from normally, relatively benign ignition sources (e.g., junction boxes)

The following methods and weaknesses have been identified for which the NRC staff review is continuing with additional Fire Modeling RAIs that may cause changes that impact the fire-affected components for a variety of fires:

x FM RAI 01.01 regarding fire propagation in cable trays x FM RAI 02.01 regarding the damage delay time for cables in covered trays

c. In the response, explain how the RG 1.205 risk acceptance guidelines are satisfied for the composite analysis. If applicable, include a description of any new modifications or operator actions being credited to reduce risk (or delta risk) as well as a discussion of the associated impacts to the fire protection program.

RESPONSE

LAR Attachment W, Section W.2 describes how the Regulatory Guide 1.205 risk acceptance guidelines are satisfied for the composite analysis. No new modifications or changes to modifications beyond those already provided in the revised LAR Attachment S (in Enclosures 6 and 7 of this letter) or operator actions beyond those already identified in the TVA response to PRA RAI 20.01 (in TVA letter dated August 29, 2014) and the revised LAR Attachment G (in Enclosure 7 of this letter) are being credited to reduce risk or delta risk.

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Containment Systems Branch (SCVB) RAI 11 NRC Generic Letter (GL) 89-13 includes the following requirement:

"Conduct, on a regular basis, performance testing of all heat exchangers, which are cooled by the service water system and which are needed to perform a safety function, to verify heat exchanger heat transfer capability."

(a) At what frequency is the Residual Heat Removal (RHR) heat exchanger performance testing performed for satisfying the above GL 89-13 requirement?

(b) Describe the GL 89-13 RHR heat exchanger performance testing method.

(c) Provide previous (prior to 2012 test) heat transfer capability results and the worst fouling factor results obtained from the GL 89-13 RHR heat exchanger tests performed at the end of service cycle.

RESPONSE

(a) In the response to Generic Letter (GL) 89-13 for BFN, dated March 16, 1990, TVA proposed an alternative to heat exchanger performance testing. The BFN GL 89-13 program requires regular inspection and cleaning. In the letter dated April 23, 1990, the NRC stated that the BFN programs, described in the March 16, 1990 letter, were either consistent with the recommended actions of GL 89-13, or represented alternative approaches that appeared to be equally effective. In addition to the performance tests referenced in LAR, Attachment X, and described in the TVA response to SCVB RAI 01 (in TVA letter dated June 13, 2014),

two other tests have been performed for the purpose of measuring Residual Heat Removal (RHR) heat exchanger performance. TVA has not used these historical tests as a basis for establishing the heat exchanger performance for safety analysis input; however, they do provide additional insight into expected fouling factors. The fouling results determined in tests performed in October 1994 and March 2001, provided in Part c of this RAI response, are in the same range as the values determined in January 2012 being used to support the increase in k-factor. Additionally, the results support that there is a large margin between the measured fouling factors and the fouling factor of 0.001517 hr-ft2-F/BTU credited in the safety analysis.

(b) As described in the TVA response to Part a of this RAI, the BFN GL 89-13 program requires regular cleaning and inspection in lieu of heat exchanger performance testing. However, the following process was used to perform heat exchanger tests in October 1994 and March 2001. A data collection device and temporary test instrumentation were installed to accurately measure fluid temperatures at the inlet and outlet of the heat exchanger.

Permanent plant instrumentation was connected to the data collection system to measure system flows. The heat exchanger was tested with the RHR system operating in the shutdown cooling mode during a plant outage. Multiple flow and temperature data points were recorded during a period of stable operation, which were then used to perform a heat balance calculation across both sides of the heat exchanger, yielding the heat transfer rate, Q. Utilizing Q, measured flows, and data from the heat exchanger manufacturers data sheet, an overall fouling resistance for the heat exchanger was determined. In these analyses, shell side fouling factor was assumed to be zero and all measured resistance was taken as tube side fouling.

(c) October 1994 Test of 2C RHR Heat Exchanger One set of test data was collected. This data set was used to calculate Q and the fouling factor.

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March 2001 Test of 2D RHR Heat Exchanger Five sets of test data were recorded. Data sets 2 and 3 were discarded because of problems with the flow data and data sets 4 and 5 did not give consistent results. Data set 1 was used to calculate Q and the fouling factor.

The following table provides a comparison of the fouling factors determined from the October 1994, March 2001, and January 2012 performance tests.

HISTORICAL TEST RESULTS CALCULATED APPROXIMATE TIME HEAT FOULING FACTOR SINCE LAST CLEANING TEST DATE EXCHANGER (hr-Ft2-F/BTU) (years)

October 1994 RHR 2C 0.00083 1.5 years March 2001 RHR 2D 0.00068 2 years Jan 2012 RHR 3A 0.000516 2 years Jan 2012 RHR 3C 0.000674 4 years Safety Analysis ALL 0.001517 NA E1-10

SCVB RAI 12 In letter dated June 13, 2014, refer to response to SCVB-RAI-6 which states:

"The SHEX model output for the NFPA 805 Case 3 containment analysis used a k-factor of 289 BTU/sec-°F. This value was subsequently adjusted to a k-factor of 270 BTU/sec-°F using a TVA suppression pool heat balance calculation model. The TVA heat balance model was benchmarked against SHEX model results and is used to evaluate the effects of small changes to SHEX model case inputs such as k-factor and UHS temperature."

Since Case 3 was the most limiting case with the least NPSH margin, the NRC staff requests the following information for this case:

(a) Why RHR heat exchanger k-factor equal to 289 BTU/sec-°F was used in the SHEX model instead of 270 BTU/sec-°F?

(b) What were the NPSH margins for k-factors equal to 289 BTU/sec-°F and k-factor equal to 270 BTU/sec-°F in the SHEX model?

(c) Provide a description of the TVA suppression pool heat balance model that was used for adjustment of results.

(d) Provide the results of benchmarking of SHEX model with the TVA suppression pool heat balance model.

RESPONSE

(a) At the time of the SHEX analysis, TVA had initially predicted that in order to obtain an acceptable peak suppression pool temperature result, it would be necessary to reduce the conservatism for two of the Case 3 SHEX inputs, i.e., k-factor and Residual Heat Removal Service Water (RHRSW) initiation time, relative to the assumptions used for Cases 1 and 2.

Therefore, a k-factor of 289 BTU/sec-°F was used versus 270 BTU/sec-°F and an RHRSW initiation time of 1.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months was used versus 2.0 hours0 days 0 hours 0 weeks 0 months . During the subsequent review process for the final calculation, TVA determined that this reduction in conservatism was not needed and that all NFPA 805 analysis cases should be done using the same input assumptions (i.e., k-factor of 270 BTU/sec-°F and an RHRSW initiation time of 2.0 hours0 days 0 hours 0 weeks 0 months .

To accomplish this, the SHEX results were adjusted for these changes using a TVA suppression pool heat balance calculation model (i.e., the TVA Model) as discussed in Part c of this RAI response.

(b) The TVA model was used to calculate an adder to account for the change in peak pool temperature resulting from the change in input assumptions. The net positive suction head (NPSH) margin values for SHEX and the TVA model are given in the table below.

Minimum RHRSW Available Required k-factor Initiation Peak Pool NPSH NPSH Minimum (BTU/sec- Time Temperature (NPSHa) (NPSHr) NPSH

°F) (hrs) (°F) (ft) (ft) Margin SHEX 289 1.5 199.1 20.67 16 4.67 TVA Model 289 1.5 196.5 22.06 16 6.04 Adder 5.9 SHEX 270 2.0 199.1+5.9=205 17.08 16 1.08 Adjusted TVA Model 270 2.0 202.4 18.66 16 2.66 E1-11

(c) The TVA T Model is a mass and energy balance mod el that includ des mass an nd energy in nputs to thee Reactor Prressure Vess sel (RPV) fro om injection n sources and decay hea at and transffer of energ gy from the RPV R to the suppression s pool via the e Safety Reliief Valves (S SRVs). The comp puter code solves the ma ass and ene ergy balance e for the Sup ppression Po ool and RPVV.

The developed d code allows for f various operating o parrameters to be entered. The code ttakes thesee inputs and performs an n integration n of several m mass, tempe erature, and pressure differrential equations. The output is the results of the ese differential equation ns.

(d) The TVA T Model was w benchm marked to NF FPA 805 Casse 3 ( see N NFPA 805 LA AR, Appendiix X,Section X.5) prior to using it tot adjust Caase 3. The T TVA Model w was run usin ng the same inputs s as the SHEX model up pon which Case C 3 was b based. The plot of resullting suppresssion pool temperature t es in the follo owing figure shows good d agreementt. The differrence at pea ak pool temperature t e is approximmately 2.65 °F.

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ENCLOSURE 2 Tennessee Valley Authority Browns Ferry Nuclear Plant, Units 1, 2, and 3 Summary of BFN NFPA 805 PRA Follow-Up RAI Response Dates CNL Letter Number /

RAI Question Number Date and Type of Response Actual Date of Response Probabilistic Risk Assessment (PRA) Follow-up RAIs PRA 01.r.01 10/7/2014 (90) CNL-14-172 October 6, 2014 PRA 04.01 10/7/2014 (90) CNL-14-172 October 6, 2014 PRA 04.c.01 10/7/2014 (90) CNL-14-172 October 6, 2014 PRA 04.k.01 10/7/2014 (90) CNL-14-172 October 6, 2014 PRA 04.l.01 10/7/2014 (90) CNL-14-172 October 6, 2014 PRA 10.c.01 10/7/2014 (90) CNL-14-172 October 6, 2014 PRA 14.01 9/9/2014 (60) CNL-14-147 August 29, 2014 PRA 19.a.01 12/17/2014 (162) CNL-14-208 December 17, 2014 PRA 19.b.01.a 10/7/2014 (90) CNL-14-172 October 6, 2014 PRA 19.b.01.b 10/7/2014 (90) CNL-14-172 October 6, 2014 PRA 19.b.01.c 12/17/2014 (162) CNL-14-208 December 17, 2014 PRA 20.01 9/9/2014 (60) CNL-14-147 August 29, 2014 E2-1

CNL Letter Number /

RAI Question Number Date and Type of Response Actual Date of Response PRA 22.01 - Discussion of 9/9/2014 (60) CNL-14-147 method August 29, 2014

- Updated risk 12/17/2014 (162) Updated risk results results included in integrated analysis provided in PRA 24.a dated December 17, 2014 PRA 24.a 12/17/2014 (162) CNL-14-208 December 17, 2014 PRA 24.b 10/7/2014 (90) CNL-14-172 October 6, 2014 PRA 24.c 12/17/2014 (162) CNL-14-208 December 17, 2014 PRA 24.d 10/7/2014 (90) CNL-14-172 October 6, 2014 SCVB RAI 11 12/17/2014 CNL-14-208 December 17, 2014 SCVB RAI 12 12/17/2014 CNL-14-208 December 17, 2014 E2-2

ENCLOSURE 3 Tennessee Valley Authority Browns Ferry Nuclear Plant, Units 1, 2, and 3 Updated TVA Response to Requests for Additional Information and Previously Submitted Update Letters This enclosure provides revisions to previous Tennessee Valley Authority (TVA) responses to NRC Requests for Additional Information (RAIs) and revisions to information provided in TVA letters dated May 30, 2014, "Update to the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187)," and September 16, 2014, "Update to the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187)."

Fire Protection Engineering (FPE) RAI 03 TVA previously responded to FPE RAI 03 by letter dated January 10, 2014 (CNL-14-001). TVA determined that the Hydraulic Analysis for Units 1, 2, and 3 New Main Transformers calculation contained a nonconservative assumption regarding flow with two pumps in operation.

Specifically, Section 3.9 of the calculation stated that "as an approximation for the two-pump supply curve, the flow from the test results for one pump is multiplied by two, with the corresponding residual pressure remaining the same." In practice, the flow with two pumps in operation will be less than twice the flow with one pump in operation.

To resolve this issue, the calculation was re-performed using AFT Fathom Version 7.0, which is a more accurate and up-to-date hydraulic modeling software than "THE" Sprinkler Program version 1.10. Therefore, references to "THE" Sprinkler Program have been replaced with references to AFT Fathom in the main body of the calculation. In addition, the hose stream allowance has been reduced from 500 gallons per minute (gpm) to 250 gpm. Using a 500 gpm hose stream allowance is not necessary because both NFPA 15 and Design Criteria BFN-50-7026 specify using 250 gpm. These changes have eliminated the need for two pump operation, i.e., only one pump is necessary to supply the water requirements for a fire in all of the safety-related areas analyzed in this calculation. of this letter provides the non security-related marked up pages showing the changes to LAR, Attachment L, "NFPA 805 Chapter 3 Requirements for Approval," described in the below revised response.

The below revised response supersedes the previous response for FPE RAI 03 in its entirety.

The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE Browns Ferry Nuclear Plant (BFN), Units 1, 2, and 3 have three electric motor-driven fire pumps located in the Intake Pumping Station (i.e., Fire Area (FA) 25-1) and one diesel-driven fire pump E3-1

located at the Number (No.) 2 Gate Structure (i.e., FA Yard). All four pumps provide high pressure fire water to the main fire header. The three electric fire pumps are not spatially separated from each other but are separated from the diesel-driven fire pump. The Intake Pumping Station and the No. 2 Gate Structure are separated from each other by over 400 feet (ft). The Intake Pumping Station and the No. 2 Gate Structure are separated from the Reactor Building by over 200 ft. All fire scenarios other than the maximum switchyard fire (i.e.,

FA Switch) require only one operating fire pump to provide sufficient suppression capability.One fire pump is sufficient to adequately supply suppression capability to each required fire protection system. For the maximum switchyard fire, two pumps are required. All four fire pumps are available for any fire in FA Switch. For FA Yard fires, all three electric fire pumps are available. For a FA 25-1 fire, the diesel-driven fire pump is available. At least one fire pump is available for all other fire areas. LAR Attachment L, Approval Request 4 is revised to remove the following statement: "and a transformer fire that requires two fire pumps will not affect the Diesel Fire Pump Building."

In a letter to the Nuclear Regulatory Commission (NRC) dated January 15, 1992, BFN submitted the Fire Protection Report (i.e., a Design Basis Document), that was supplemented with a comparison of BFN to Branch Technical Position (BTP) Chemical Engineering Branch (CMEB) 9.5-1. BTP CMEB 9.5-1, Sections C.6.b(6)(a) and (b) state in part "Each pump and its driver and controls should be located in a room separated from the remaining fire pump by a fire wall with a minimum rating of three hours." This part of BTP CMEB 9.5-1, Sections C.6.b(6)(a) and (b) is equivalent to NFPA 805 Section 3.5.5. In response to Sections C.6.b(6)(a) and (b),

BFN discusses that there are three 100% capacity electric fire pumps that are physically separated from the one 100% diesel fire pump. The NRC responded in a letter to BFN dated March 31, 1993, documenting the NRC Safety Evaluation (SE) of the Fire Protection Report (FPR). Section 2.14 of the NRC SE, titled "Fire Protection Water Supply Systems," addresses this fire pump configuration. Within Section 2.14 of the NRC SE, numerous aspects of the system, including number of pumps, size and rating of pumps, and fire main design are listed.

In the NRC SE Section 3.0, "Conclusions," it is stated that the "licensees Fire Protection Plan and Fire Hazards Analysis described in BFN-FPR was reviewed and found acceptable." The NRC SE Section 3.0 concludes by stating, "Consequently, based on this SE and the SEs mentioned above, the staff concludes that TVA's fire protection program described by the BFN-FPR submitted on January 15, 1992, conforms with BTP CMEB 9.5-1 and is therefore acceptable." The current configuration of the fire pumps is identical to the configuration that existed at that time.

Therefore, the "complies with previous approval" statement in LAR Attachment A, Section 3.5.5, Water Supply Pump Separation, relies on the existing four pump configuration, NRC approval of TVA's fire protection program's conformance with BTP CMEB 9.5-1, and the equivalency of BTP CMEB 9.5-1, Sections C.6.b(6)(a) and (b) to NFPA 805 Section 3.5.5.

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FPE RAI 04 TVA previously responded to FPE RAI 04 by letter dated January 10, 2014 (CNL-14-001). TVA determined that the test described in the original response would result in risk to the operation of the plant, and that raw service water (RSW) demand would not allow for running cooling tower lift pump bearing lube water without a fire pump. Therefore, TVA has determined that a modification is needed to correct the deficiency of running a fire pump to support normal plant operations.

Enclosure 6 of this letter provides the non security-related marked up pages showing the changes to LAR, Attachment S, Table S-3, "Implementation Items," and LAR Attachment A, "NEI 04-02 Table B-1 Transition of Fundamental Fire Protection Program & Design Elements,"

described in the revised response. Enclosure 7 provides the security-related marked up pages showing the changes to LAR, Attachment S, Table S-2, "Plant Modifications Committed,"

described in the revised response.

The below revised response supersedes the previous response for FPE RAI 04 in its entirety.

The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE High Pressure Fire Protection (HPFP) System pressure is maintained by an interconnection to the raw service water (RSW) System. The National Fire Protection Association (NFPA)

Standard 20 code compliance review identified that a fire pump is often utilized to supplement the RSW System when the RSW System cannot meet the total demand. Challenges to RSW System demand have occurred when cooling towers are in service, which have resulted in inadequate flow and pressure to the bearing lubricating water supply for the cooling tower lift pumps.

Design Change Notices (DCNs) 70332, 70337 and 70351 have been implemented to install duplex strainers upstream of the cooling tower lift pump stations to improve RSW System performance. Subsequently, a test of the RSW System will be performed to confirm that these modifications were successful in precluding the need to run a fire pump to support system load.

License Amendment Request (LAR) Attachment S, Table S-3, Implementation Item 44 is revised to state the following:deleted and a new modification (i.e., Modification 106) is added to LAR Table S-2 as follows:

"Install additional equipment to provide water to the cooling tower lift pump bearing lubrication water system in order to provide this system a water supply independent from the RSW and HPFP systems to ensure that pressure is maintained in the fire protection system during normal operation without using a fire pump."

LAR Attachment A, NFPA 805 Chapter 3 Reference 3.5.8, is also revised to reflect the deletion of LAR Table S-3, Implementation Item 44, and incorporation of LAR Table S-2, Modification 106.

"Implement corrective actions as required to ensure that pressure is maintained in the fire protection system during normal operation without using a fire pump. In addition, perform testing of the Raw Service Water System to confirm that pressure is maintained in the fire protection system during normal operation without using a fire pump."

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FPE RAI 05 TVA previously responded to FPE RAI 05 by letter dated January 10, 2014 (CNL-14-001).

Additional changes have been made to eliminate some applications of 1-hour rated Electrical Raceway Barrier Systems (ERFBSs) in fire areas that do not have automatic suppression. The ERFBS to address VFDR 05-0006 is being changed to a 3-hour rated barrier. The ERFBS to address VFDR 21-0007 is being eliminated by re routing the subject cable out of FA 21.

As described in the January 10, 2014, TVA response to FPE RAI 05, Existing Engineering Equivalency Evaluations (EEEEs) are no longer used to demonstrate that the ERFBS is adequate for the hazard without credit for suppression. Therefore, references to EEEEs have been deleted in LAR Tables C-1, "NFPA 805 Ch 4 Compliance (NEI 04-02 Table B-3) 791,"

and C-2, "NFPA 805 Required Fire Protection Systems and Features," as shown in Enclosure 7 and Enclosure 6, respectively. LAR Attachment V,Section V.2.5 has been revised to delete "In addition, the engineering equivalency evaluation is referenced in Tables C1 and C2," as shown in Enclosure 6.

The below revised response supersedes the previous response for FPE RAI 05 in its entirety.

The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE There are sixfour instances involving 1-hour ERFBS in fire areas that do not have automatic suppression. These are shown in the Table below. In each of these instances, the ERFBS iswas not yet installed when the LAR was submitted, and a separation issue is tracked by one or more VFDRs identified in the table below. The analysis results presented in the LAR were based on resolving the VFDRs by installing 1-hour ERFBS and an Engineering Equivalency Evaluation (EEE) to demonstrate that the ERFBS is adequate for the hazard without credit for suppression. This method resulted in a deterministic resolution of the VFDR, wherein the probability of ERFBS failure is not reflected in the delta () Core Damage Frequency (CDF) for the fire area.

Fire Cable Associated Configuration VFDR LAR Table S-2 Area Protected Equipment No. Item No.

5 PP626-IB 4kV Shutdown 1-hour rated VFDR- 87 ES50-I (Sd) Board (Bd) ERFBS, 05-0006 B AC load Detection, cables (two Manual cables to suppression prevent fault propagation) 12 3B180-B1 4kV Sd Bd 3EA 1-hour rated VFDR- 14 DC control ERFBS, 12-0006 power cable Detection, Manual suppression E3-4

Fire Cable Associated Configuration VFDR LAR Table S-2 Area Protected Equipment No. Item No.

13 3PL6363-II 480v Sd Bd AC 1-hour rated VFDR- 17 3PL451-II power cables ERFBS, 13-0005 Detection, VFDR-Manual 13-0008 suppression 21 3B188-B3 4kV Sd Bd 3EC 1-hour rated VFDR- 91 control power ERFBS, 21-0006 cable Detection, Manual suppression 21 3B193-B2 4kV Sd Bd 3ED 1-hour rated VFDR- 92 control power ERFBS, 21-0007 cable Detection, Manual suppression 23 3B180-B1 VFDR- 14 4kV Sd Bd 3EA 1-hour rated 23-0009 DC control ERFBS, power cable Detection, Manual suppression TVA has re-considered the use of EEEs for this application and has decided not to disposition 1-hour ERFBS without automatic suppression as adequate for the hazard. The current plan for these applications is to install 1-hour ERFBS and to resolve the VFDRs using the fire risk evaluation process. Documentation affected by this change will be revised. In addition, LAR Attachment V,Section V.2.5 is revised by deleting the fourth sentence of the first paragraph and replacing it with the following:

"In those instances, the separation issues will be resolved using the fire risk evaluation process."

Thus, the first paragraph of LAR Attachment V,Section V.2.5 now reads:

"BFN has Electrical Raceway Fire Barrier Systems (ERFBS) installed, and modifications planned to install ERFBS, in accordance with NFPA 805 Chapter 3 Section 3.11.5 to meet the separation requirements of NFPA 805 Chapter 4 Section 4.2.4. In most cases the ERFBS are 1-hour rated and are or will be installed in areas where automatic detection and suppression is available. In some cases, the 1-hour rated ERFBS may not have automatic suppression. In those instances, the separation issues will be resolved using the fire risk evaluation process. The ERFBS are referenced in Tables C-1 and C-2 as a required Fire Protection System/Feature for the Fire Area. In addition, the engineering equivalency evaluation is referenced in Tables C-1 and C-2."

Separation issues and resolutions which involve ERFBS are documented in the Fire Risk Evaluation calculation. LAR Attachment C, Table C-2 also identifies that credit will be taken for a modification to install ERFBS as a fire protection feature and identifies resolution by denoting E3-5

the ERFBS modification as "Separation" or "Risk." After this change in method is implemented, the affected sections in the LAR will be revised to reflect the results of the updated fire risk evaluations. The revision to the LAR will be provided to the NRC after the Fire PRA is updated and additional quantification is performed in response to remaining NRC Requests for Additional Information (RAIs).

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FPE RAI 07 TVA previously responded to FPE RAI 07 by letter dated December 20, 2013 (CNL-13-141).

The December 20, 2013 response provided specific modification numbers that were crediting Thermo-Lag. Modification scope changes have modified this list. In order to preclude revising the response when modifications are changed in the future, references to these modifications and Design Change Notices (DCNs) are removed. When modifications involving ERFBS are changed in the future, these changes will not affect this RAI response.

The below revised response supersedes the previous response for FPE RAI 07 in its entirety.

The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE AllThe credited Electrical Raceway Fire Barrier Systems (ERFBS) for the post-transition plant configuration are Thermo-Lag. Table 9.3.11.H of the FPR lists the currently installed ERFBS, all of which utilize Thermo-Lag 330-1.

The current plan for the NFPA 805 transition ERFBS modifications is to utilize Thermo-Lag as the one-hour barrier for wrapping cables, conduits, and junction boxes. This includes LAR Table S-2, Modification Items 14, 17, 42, 46, 57, 65, 67, 74, 87, 91, and 92. Design Changes (DCNs) 707462 and 70492 have been issued for Modification Items 14 and 17, respectively.

Both specify using Thermo-Lag 330-1 as the ERFBS.

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FPE RAI 10 TVA previously responded to FPE RAI 10 by letter dated March 14, 2014 (CNL-14-025). LAR Attachment S, Table S-2, Modifications 78 and 79 proposed modifications to install an area wide incipient (i.e., very early warning) fire detection system, that uses very early warning fire detectors and a new automatic gaseous fire suppression system in the Cable Spreading Rooms (CSRs). TVA has decided not to install the area wide very early warning fire detection system (VEWFDS) and the automatic gaseous suppression system in the CSRs. Fire modeling refinements have been made which resulted in acceptable baseline risk values without credit for proposed incipient detection and gaseous suppression systems. With these refinements, credit for existing detection and suppression was found to be sufficient. The fire modeling refinements are described in the TVA letter dated September 16, 2014, Enclosure 3. In addition, TVA has determined that an implementation item is required to ensure that training is developed and implemented for incipient detection system alarm response. Enclosure 6 of this letter provides non security-related marked up pages showing the changes to LAR, Table S-3 described in the revised response. Enclosure 7 of this letter provides security-related marked up pages showing the changes to LAR, Table S-2 described in the revised response. Enclosure 7 of this letter also provides the revised PRA risk results incorporating the deletion of Modifications 78 and 79 in the security-related markup of LAR, Attachment W.

The below revised response supersedes the previous response for FPE RAI 10 in its entirety.

The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE LAR Attachment S, Table S-2 identifies three modifications associated with incipient detection systems (i.e., very early warning fire detection systems). These three modifications are Items 3, 77, and 78.

LAR Attachment S, Table S-2, Item 77 proposes modifications to install area wide incipient detection (i.e., a very early warning fire detection system) in the auxiliary instrument rooms (Fire Compartments 16-K, 16-M, and 16-O). TVA has decided not to install the area wide very early warning fire detection system in the auxiliary instrument rooms. This decision was made because the risk increase of removing the credit for prompt detection is less than 1% total plant Core Damage Frequency (CDF) and Large Early Release Frequency (LERF). Therefore, the effect on the Fire PRA is negligible. LAR Table S-2 is revised to delete Item 77. In addition, LAR Section V.2.4 is revised to remove discussions of credit for area wide very early warning fire detection in the auxiliary instrument room (see Enclosure 1, Attachment 1 of TVA letter dated March 14, 2014this enclosure). The TVA response to FPE RAI 12, Part c provides further information on the effect of removing the area wide very early warning fire detection system from the Fire Probabilistic Risk Assessment (PRA). In-cabinet protection will stillis be provided as discussed below.

The detection systems identified in LAR Attachment S, Table S-2, Item 78 will provideproposes area wide coverage incipient fire detection systems for the Units 1, 2, and 3 Cable Spreading Rooms (CSRs). TVA has decided not to install the area wide very early warning fire detections systems in the CSRsThese systems have not been designed and are addressed in the TVA response to FPE RAI 12, Part d (in this enclosure). A discussion of the current conceptual design approach is also provided in the TVA response to FPE RAI 12, Part d.

LAR Attachment S, Table S-2, Item 3 addresses incipient detection to bethat has been installed in the electrical panels in the Units 1, 2, and 3 Auxiliary Instrument Rooms. These detection E3-8

systems have been designed and the modifications are beinghave been implemented. These detection systems are addressed in the remainder of this RAI response.

NFPA 72-2010, "National Fire Alarm and Signaling Code," applies to these detection systems along with meeting the requirements of NFPA 76-2012, "Standard for the Fire Protection of Telecommunications Facilities," for response transport times and sensitivity settings. Code compliance reviews will be performed as part of implementationThe installed area wide very early warning fire detections systems have been designed in accordance with and meet the requirements in these codes.

The design of the detection systems will includes one detector installed in each Auxiliary Instrument Room, with each detector monitoring four zones. Each of the four zones will monitors the electrical panels in one of the four rows of panels. The detection system would send an alarm to the main control room (MCR) fire alarm annunciator and Fire Operations annunciator. This would alert personnel to respond to a potential fire so it cancould be extinguished manually during the incipient stage. The system will indicates which of the four zones are in alarm to permit personnel to investigate the row of panels from which the alarm is originating.

Testing and commissioning of each incipient detector will behave been completed in accordance with the vendors acceptance test and associated sensitivity testing. The vendor commissioning of the detector demonstrates compliance with criteria established by applicable standards, which includes testing the sensitivity and transport time. In accordance with NFPA 76, this type of system is required to have a transport time of no greater than 60 seconds from any one sampling point. The sensitivity and setpoints will beare controlled by surveillance procedure(s). Routine inspection, testing and maintenance will be conducted in accordance with vendor recommendations, including sensitivity and transport time tests.

Procedures and training will be developed as part of NFPA 805 implementation covering responses to an alarm. Personnel will respond to alarm conditions to locate the source and extinguish any fire that may occur. To ensure that procedures are developed and training is provided, a new implementation item, Item 48, is added to LAR Table S-3. The LAR table requires that certain items be completed prior to implementation of the NFPA 805 fire protection program. The new implementation item reads: "Develop and deliver training to Fire Operations on incipient detection systems alarm response procedures."

Design and installation will beare in compliance with each of the elements, limitations and criteria of NUREG/CR-6850, Supplement 1, "Fire Probabilistic Risk Assessment Methods Enhancements," Chapter 13, and FAQ 08-0046 including the closeout memo (ADAMS Accession No. ML093220426) with no deviations.

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FPE RAI 11, Part b TVA previously responded to FPE RAI 11, Part b, by letter dated March 14, 2014 (CNL-14-025).

LAR Attachment S, Table S-2, Modifications 78 and 79 proposed modifications to install an area wide incipient (i.e., very early warning) fire detection system, that uses very early warning fire detectors and a new automatic gaseous fire suppression system in the CSRs. TVA has decided not to install the area wide VEWFDS and the automatic gaseous suppression system in the CSRs. Fire modeling refinements have been made which resulted in acceptable baseline risk values without credit for proposed incipient detection and gaseous suppression systems. With these refinements, credit for existing detection and suppression was found to be sufficient. The fire modeling refinements are described in the TVA letter dated September 16, 2014, . Enclosure 7 of this letter provides the security-related marked up pages showing the changes to LAR, Table S-2 described in the revised response. Enclosure 7 of this letter also provides the revised PRA risk results incorporating the deletion of Modifications 78 and 79 in the security-related markup of LAR, Attachment W.

The below revised response supersedes the previous response for FPE RAI 11, Part b in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE Part b Fire modeling refinements were performed for the CSRs, as discussed in the TVA letter to the NRC dated September 16, 2014 (CNL-14-160). These fire modeling refinements, off-set the risk benefit of the proposed modification described in Attachment S, Table S-2, Modification 78 to install area wide incipient (i.e., very early warning) detection systems, using very early warning fire detectors (VEWFDS). Therefore, this modification will not be installed.

LAR Attachment S, Table S-2, Item 79 had proposed modifications to install a new automatic gaseous suppression system in the CSRs. The fire modeling refinements discussed in the TVA letter to the NRC dated September 16, 2014 (CNL-14-160) off-set the risk benefit of this modification. Therefore TVA has decided not to install the new automatic gaseous suppression system in the CSRs.

LAR Table S-2 is revised to delete Items 78 and 79. In addition, LAR Section V.2.4 is revised to remove discussions of the area wide incipient detection system in the CSR and the automatic gaseous suppression system in the CSRs. The Fire PRA has been updated to remove the credit for the incipient detection system in the CSR and the automatic gaseous suppression system in the CSRs.

LAR Attachment S, Table S-2, Modifications 78 and 79 propose modifications to install an area wide very early warning fire detection system and a new automatic gaseous fire suppression system in the CSRs. Although the designs for these modifications are still conceptual, the design details for the proposed area wide very early warning fire detection system and the total flooding clean agent system in the CSR portion of Fire Compartment 16-A, are provided in the TVA responses to FPE RAI 10 (Modification 78 only) and FPE RAI 12, Part d (Modifications 78 and 79).

As discussed in LAR Attachment V,Section V.2.4, the Fire PRA applies a prompt detection credit and an automatic suppression credit for transient fires, cable fires caused by welding and cutting, transient fires caused by welding and cutting, and self-ignited cable fires.

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The Fire PRA credit for the area wide detection system is discussed in detail in the TVA response to PRA RAI 10, Part a. With the exception of the sampling point locations (i.e., area wide versus in-cabinet), the Fire PRA credit was applied consistent with the guidance from NUREG/CR-6850 and NUREG/CR-6850, Supplement 1 (i.e., FAQ 08-0046) and is justified as follows:

x Both area wide and in-cabinet very early warning fire detection systems are required to be designed and installed to the same codes and standards (i.e., NFPA 72 and NFPA 76) and are required to be listed by a nationally recognized testing laboratory (i.e., Underwriter's Laboratory (UL)).

x The appropriate manual fire suppression failure probabilities in NUREG/CR-6850, Supplement 1 (i.e., FAQ 08-0050) are selected based on the specific initiator.

x The unavailability and unreliability of the area wide very early warning fire detection system is considered equivalent to an in-cabinet system, as further discussed in the TVA response to FPE RAI 12, Part a.

x The detection system unavailability and unreliability value of 1E-02 from FAQ 08-0046 is appropriately included.

x Prompt detection has been credited for the subject CSR fire scenarios in accordance with the guidance from NUREG/CR-6850, Appendix P for a high-sensitivity smoke detection system.

x Even when the detection system and manual suppression, via the fire watch for welding and cutting scenarios, are successful, the analysis still assumes damage to one cable tray. The tray damaged by the fire is conservatively assumed to be one of the top 25 risk contributing cable trays in Fire Compartment 16-A for each unit.

x Fire scenario end states for unsuccessful detection or suppression conservatively assume all targets in the respective units CSR are damaged (i.e., whole room damage).

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FPE RAI 12 TVA previously responded to FPE RAI 12, Parts a, b, and d, by letter dated March 14, 2014 (CNL-14-025). LAR Attachment S, Table S-2, Modifications 78 and 79 proposed modifications to install an area wide incipient (i.e., very early warning) fire detection system, that uses VEWFDs, and a new automatic gaseous fire suppression system, in the CSRs. TVA has decided not to install the area wide very early warning fire detection system and the automatic gaseous suppression system in the CSRs.

The below revised response supersedes the previous response for FPE RAI 12, Parts a, b, c, and d in their entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE LAR Attachment S, Table S-2, Modifications 78 and 79 propose modifications to install, in the CSRs, an area wide incipient (i.e., very early warning) fire detection system, that uses very early warning fire detectors (VEWFDs), and a new automatic gaseous fire suppression system. As discussed in the TVA response to FPE RAI 10, TVA has determined that the proposed modification described in LAR Attachment S, Table S-2, Modification 77 to install area wide very early warning fire detection systems in the auxiliary instrument rooms (i.e., Fire Compartments 16-K, 16-M, and 16-O), and discussed in LAR Attachment V,Section V.2.4, will not be installed.

Parts a, b, and d As discussed in the revised TVA responses to FPE RAI 10 and FPE RAI 11, Part b, in this enclosure, TVA has determined that the proposed modifications described in Attachment S, Table S-2, Modification 78 to install area wide incipient (i.e., very early warning) detection systems, using VEWFDS, and Modification 79 to install a new automatic gaseous suppression system in the CSRs, and discussed in LAR Attachment V,Section V.2.4, will not be installed.

The CSR area wide very early warning fire detection system will actuate a total flooding gaseous suppression system. Additional design information for these systems and further details regarding how the detection system will be used to actuate the automatic suppression system are provided in the TVA response to FPE RAI 12, Part d.

The availability and reliability of the CSR area wide very early warning fire detection system is equivalent to in-cabinet very early warning fire detection systems based on the following:

x Both area wide and in-cabinet very early warning fire detection systems are required to be designed and installed to the same codes and standards (i.e., NFPA 72 and NFPA 76) and are required to be listed by a nationally recognized testing laboratory (i.e., UL).

x The obscuration criteria and location of detectors (i.e., pipe openings) for area wide detection systems will follow NFPA 72 standards, NUREG/CR 6850, Supplement 1, Section 13.2, and manufacturer listings. NFPA 76, as referenced in FAQ 08-0046, provides guidance on area wide application of the detection systems.

x Area wide detection systems will be operated in accordance with referenced standards such as NFPA 76 and NFPA 72, and manufacturer requirements, that are the equivalent to the standards regulating the in-cabinet detection systems.

x The air sampling detectors will follow routine maintenance and inspection procedures to ensure optimum reliability and availability of the detector. Availability of the area wide systems is similar to in-cabinet protection methods as the same protocols will apply in E3-12

terms of maintenance and monitoring. The detection system will be supervised for multiple troubles; failures will be indicated by a trouble signal on the fire alarm system that reports to the MCR fire alarm annunciator and Fire Operation's annunciator. If area wide fire detection is unavailable, then compensatory measures will be provided, consistent with the methodology for in-cabinet detection systems.

Part b Although the designs for the modifications installing the area wide very early warning fire detection system and automatic gaseous fire suppression system in the CSR portion of Fire Compartment 16-A are still conceptual, the following discussion provides the current modification approach.

The new detection system will also be used to activate the clean agent gaseous suppression systems. The gaseous suppression systems will provide area wide coverage for the entire CSR, regardless of the location of the top 25 risk contributing cable trays.

Specific design and plant operation information is provided in the TVA response to Part d of this RAI, for the detection and gaseous suppression systems.

The TVA response to Part d of this RAI also provides additional design details for the detection system, including the type of system, location of sampling points, and how the detection system will actuate the automatic suppression system.

Part c The prompt detection credit was taken for two transient fire scenarios in the Unit 1 auxiliary instrument room (i.e., Fire Compartment 16-K) based on the proposed plant modification for the installation of an area wide very early warning fire detection system in the fire compartment (i.e., LAR Attachment S, Table S-2, Modification 77). This modification will not be installed, as discussed in the initial paragraph of this response. Therefore, prompt detection in Fire Compartment 16-K will no longer be credited for transient fire scenarios.

A sensitivity analysis has been performed to analyze the effect of removing the prompt detection credit (i.e., by removing suppression from the transient fire scenarios). The risk increase results from the removal of the prompt detection credit for two transient fire scenarios in Fire Compartment 16-K, are provided in Table FPE RAI 12.c, in Attachment 2 to this enclosure.

The risk increase of removing the credit for prompt detection is less than 1% total plant Core Damage Frequency (CDF) and Large Early Release Frequency (LERF). Therefore, the effect on the Fire PRA is negligible. The Fire PRA will be updated to remove the credit for the area wide fire detection system in Fire Compartment 16-K. LAR Attachment W will be revised to reflect the results of the updated Fire PRA quantifications. The revision to the LAR will be provided to the NRC after the Fire PRA is updated and additional quantification is performed in response to the remaining NRC RAIs.

Part d Although the proposed designs for the modifications installing the area wide detection system and automatic gaseous fire suppression system in the CSR portion of Fire Compartment 16-A are still conceptual, the following discussion provides the current modification approach.

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The detection system will be designed to locate sampling points for area-wide detection to provide optimum coverage for the detection scheme. The detection system will be capable of sending a signal to actuate a total flooding clean agent suppression system. The detection system will be designed and installed in accordance with NFPA 72-2010 and will meet the requirements of NFPA 76-2012 for response transport times and sensitivity settings. The clean agent suppression system will be designed in accordance NFPA 2001-2012.

The detection system will have alarm thresholds, where the lower level alarm thresholds will initiate a signal to the plant fire alarm system. These lower level alarm thresholds will not initiate activation of the clean agent suppression system. A higher level alarm threshold will actuate the clean agent suppression system for the room being monitored. The design of the suppression system will incorporate adequate gaseous concentrations to perform the required suppression function. Nozzles will be located to be capable of properly extinguishing a fire in the CSRs.

There will be no time delay factored into the activation of the clean agent suppression system once the highest alarm threshold is achieved.

The TVA response to PRA RAI 10 discusses how the designs are treated in the Fire PRA.

E3-14

Safe Shutdown Analysis (SSA) RAI 03 TVA previously responded to SSA RAI 03 by letter dated January 14, 2014 (CNL-14-006). This revision reflects a change in analysis approach described in the revised TVA response to FPE RAI 05 in this enclosure. This revision is consistent with the revised TVA response to FPE RAI 05.

The below revised response supersedes the previous response for SSA RAI 03 in its entirety.

The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE Electrically-induced secondary fires can potentially result from the failure of a circuit breaker to isolate an electrical fault caused by the initial fire. Larger circuit breakers require control power to operate, and fire events can cause breaker control power to be lost. Within a fire event time sequence, such a loss of control power may be early (e.g., the initial fire damages the cable providing control power to an electrical board) or late (e.g., the fire fails a battery charger or its power supply such that the available control power voltage degrades over time as the associated battery depletes). The details regarding potential secondary fires resulting from the special case of CT open circuits are discussed separately in the TVA response to Safe Shutdown Analysis (SSA) RAI 02 in this enclosureTVA letter dated January 14, 2014.

The BFN NFPA 805 transition strategy to address potential secondary fires is two-fold.

1) AnyThe majority of Variances from Deterministic Requirements (VFDRs) related to early control power loss concurrent with the potential for an associated power cable fire-induced fault isare being deterministically resolved by a plant modification such that the secondary fire initiation vulnerability is removed. However, there are some applications of 1-hour rated ERFBS in fire areas without automatic suppression where the VFDR resolution does not meet deterministic separation requirements.

These VFDRs are resolved by the performance based approach. These ERFBS applications are provided in revised TVA response to FPE RAI 05 in this enclosure.

The plant response to secondary fires is not modeled in the PRA, and application of ERFBS that do not meet deterministic separation requirements to VFDRs involving secondary fires due to failure of fault protection is limited. In these cases, equipment and cables affecting circuit breaker control power and power cables requiring fault protection will be sufficiently separated such that they are not damaged in a single fire scenario. Thus secondary fire events are prevented.

2) Regarding the late loss of control power situations, the VFDR risk was evaluated by the Fire PRA. The Fire PRA determined the risk was insignificant from potential secondary fires resulting from breaker control power loss due to battery depletion. This determination was based on the following failure probabilities and timing sequence relationship factors:

x battery time-to-depletion analyses x low probability of failure to restore a battery charger within the available battery depletion timeframes x low probability of fire non-suppression within battery depletion time E3-15

x low probability of fires that fail battery chargers while also failing a target power cable of concern.

Considering the factors cited in the four bullet points above for late control power loss situations, the initiation of a secondary fire would require the following events and human failure actions:

a) Loss of the control power battery charger soon after the onset of the fire. A delay in the charger loss would add to the length of time the board retained control power.

Delayed charger loss would allow greater time for breaker control power to function while the fire is being suppressed.

b) Inability of BFN fire operations personnel to suppress the fire to prevent further damage within the battery depletion time once the charger was lost.

c) Failure by BFN staff to transfer the board to an alternate control power supply or restore the associated charger to service prior to battery depletion.

d) Development of fire damage such that an associated power cable faults only after battery depletion.

e) Energizing the associated power cable (i.e., its breaker closed) when it is damaged.

The occurrence of the preceding set of events was judged to be so improbable as to be incredible, that plant risk was insignificant, and such potential secondary fires did not warrant further modeling in the Fire PRA. Because the occurrence of an electrically-induced secondary fire for late control power loss is considered incredible, no secondary fire locations exist, no components are involved in a secondary fire, and no recovery actions are impeded or affected by a secondary fire.

Evaluations for DID and SM were performed consistently for all of the FAs within the scope of the NFPA 805 transition project. The qualitative DID evaluation for the potential secondary fire initiation issues verified that appropriate balance existed between the three DID elements of:

1) fire prevention, 2) rapid fire detection, control, and extinguishment, and 3) providing adequate protection for plant essential safety systems against fire effects. DID recovery actions were established where necessary to improve this balance.

Regarding the potential for secondary fire initiation, the BFN NFPA 805 philosophy for establishing DID recovery actions for VFDRs related to late control power loss secondary fires was:

x For VFDRs involving safety related electrical boards which might incur a late control power loss, DID recovery actions to restore battery chargers or transfer to an alternate control power source were established.

x For VFDRs involving loss of non-safety related battery chargers, DID balance did not require the establishment of formal recovery actions for such low probability events.

While preparing the response to this RAI, TVA identified two instances where safety related board VFDRs involving a late loss of control power (i.e., VFDR 02-03-0026 and VFDR 16-0228) did not have an associated DID action, contrary to the BFN NFPA 805 DID philosophy stated above. These two instances were entered into the site corrective action program for resolution.

The revision to the LAR, reflecting the Fire Risk Evaluation update, will be provided to the NRC after the Fire Risk Evaluation is updated in response to the remaining NRC RAIs.

SM criteria require the evaluation of the analytical techniques applied to ensure that adequate margin exists to account for uncertainties. Regarding the potential secondary fire initiation issues, the SM evaluation considered the battery capacity analyses, the Fire PRA, and the fire E3-16

modeling analyses which support the Fire PRA. The evaluation concluded adequate margin exists in these analyses and their methodologies.

In summary, the loss-of-control power condition which results in a breakers inability to open under a fault condition was addressed in the BFN NFPA 805 transition by:

1) Ensuring that no early loss of direct current (DC) control power will occur for breakers protecting power cables that could be faulted in the same FA. Plant modifications were identified as appropriate to address the related VFDRs.

and by

2) The Fire PRA judging the risk to be insignificant from fire-induced faults which could occur only after battery depletion.

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SSA RAI 04 TVA previously responded to SSA RAI 04 by letter dated December 20, 2013 (CNL-13-141).

The December 20, 2013, response provided TVA's justification for assuming hot shorts for 3-phase AC power circuit cable-to-cable proper phase sequence faults and 2-wire ungrounded DC motor power cable-to-cable proper polarity faults only for high/low pressure interfaces. TVA has subsequently determined that future analyses considering the effects of a hot short on circuits required for safe shutdown equipment will not consider hot shorts for 3-phase AC power circuit cable-to-cable proper phase sequence faults and 2-wire ungrounded DC motor power cable-to-cable proper polarity faults for high/low pressure interfaces. Enclosure 6 of this letter provides the non security-related marked up pages showing the changes to LAR, Attachment B, "NEI 04-02 Table B-2 Nuclear Safety Capability Assessment - Methodology Review,"

associated with the revised response.

The below revised response supersedes the previous response for SSA RAI 04 in its entirety.

The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE NEI 00-01, Revision 1, Section 3.5.2.3, "Circuit Failures Due to Hot Short," provides guidance for analyzing the effects of a hot short on circuits for required safe shutdown equipment. This section includes an example of a typical ungrounded control circuit. However, Section 3.5.2.3 does not discuss the circuit failures excluded from deterministic analysis allowed in NEI 00-01, Revision 1, Appendix B. The "aligns with intent" statement in LAR Attachment B, Table B-2, Section 3.5.2.3, was made to clarify that hot short circuit failure exclusions are not discussed in Section 3.5.2.3 but, are included in NEI 00-01, Revision 1, Appendix B.

In accordance with NEI 00-01, Revision 1, Appendix B.1, "Justification for the Elimination of Multi-Conductor Hot Short Involving Power Cables," for a three-phase alternating current (AC) power cable, the potential for a fire to cause a hot short on all three phases in the proper sequence to that results in a spurious operation is highly unlikely for the following reasons:

x The aggressor cable would need to be a 3-phase power cable in the same raceway x The aggressor cable would need to be energized x The overcurrent protection device for the aggressor circuit would need to be set sufficiently high to ensure the valve motor starting current would not trip the breaker when the valve motor initially started running x Both the aggressor and target power cables would need to have the cable insulation fail to hot short the three phase conductors without them shorting to each other or shorting to ground x The aggressor cable would need to short to the target cable in the exact sequence necessary for the valve to operate to the undesired position Similar arguments may be used to demonstrate the implausibility of consequential hot shorts on a direct current (DC) reversing motor of a motor operated valve.

x A typical reversing DC compound motor power circuit uses five conductors and must energize a series field, a shunt field, and an armature for the motor to operate. The polarity of the armature determines the direction of the motor. For this type of motor, two specific conductors of the power cable would require a hot short from an aggressor cable (of the same and correct polarity).

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x A conductor-to-conductor short must occur between two other specific conductors of the power cable, in order to bypass the Open or Close contactor.

x The power fuses for the affected valve must remain intact to provide an electrical return path.

x An additional hot short of the opposite polarity would be required to cause valve operation if the power fuses were blown by the faults.

The likelihood of all of these faults occurring, without grounding (i.e., causing fuses of the aggressor, or target circuits to blow), is very low. Additionally, there are far fewer DC power cables in a plant, and even fewer, if any, continually running DC loads in the plant to serve as aggressors, making the possibility of consequential hot shorts in DC power cables for compound motors as implausible as three-phase consequential hot shorts.

NEI 00-01 Revision 2, Table B.1-0, carries forward the determination that 3-phase AC hot shorts and proper polarity DC motor hot shorts are only required to be considered for high/low pressure interfaces.

Therefore, considering hot shorts for 3-phase AC power circuit cable-to-cable proper phase sequence faults and 2-wire ungrounded DC motor power cable-to-cable proper polarity faults only for high/low pressure interfaces is justified.

Subsequent to the project instruction for the Browns Ferry Post-Fire Safe Shutdown Cable Identification, NUREG/CR-7150, Volume 1 (EPRI Report 1026424), "Joint Assessment of Cable Damage and Quantification of Effect from Fire (JACQUE-FIRE),"

was issued in October 2012. In this report, irrespective of high/low pressure interface consideration, the Phenomena Identification and Ranking Table (PIRT) panel concluded the spurious operation of a three-phase AC motor due to proper polarity hot shorts on three-phase power cabling is incredible and the spurious operation of DC compound-wound motors due to proper polarity hot shorts in the motive/power cabling is incredible.

As defined in the report, the term "incredible" used in conjunction with the phenomenon of a fire-induced circuit failure, signifies the PIRT panel's conclusion that the event cannot occur. In these cases, the PIRT panel could find no evidence of the phenomenon ever occurring, and there were no credible engineering principles or technical argument to support it happening during a fire. Any likelihood value assigned to these types of phenomena would have little meaning. Therefore, TVA does not consider these types of circuit failures as credible based on the PIRT panel conclusions.

E3-19

SSA RAI 06 TVA previously responded to SSA RAI 06 by letter dated January 14, 2014 (CNL-14-006). TVA letter dated August 28, 2014, "Third Six-Month Status Report and Revised Overall Integrated Plan in Response to the March 12, 2012, Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond- Design-Basis External Events (Order Number EA-12-049) for Browns Ferry Nuclear Plant (TAC Nos. MF0902, MF0903, and MF0904)," revised the Overall Integrated Plan for FLEX, removing the 3 Megawatt (MW) Diesel Generators (DGs). Consequently, in order to provide backup AC power to the Emergency High Pressure Makeup (EHPM) system, DGs will be installed, capable of supplying backup power to all three EHPM systems simultaneously.

The below revised response supersedes the previous response for SSA RAI 06 in its entirety.

The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE LAR Attachment S, Table S-2 Modification 35 proposes modifications to install a new EHPM pump for each unit capable of injecting water into the reactor vessel at high pressure. LAR Attachment S, Table S-2, Modification 35a proposes modifications that would provide the capability of supplying power to the EHPM pumps from new diesel generators (DGs) that are being installed as part of BFN Flexible and Diverse Coping Mitigation Strategies (FLEX)

Integrated Plan submitted to the NRC by letter dated February 28, 2013 (ADAMS Accession Number ML13064A465). Although the designs for these modifications are not finalized, the following discussions provide the current modification approach.

General Design Each unit will have a motor driven EHPM pump and associated valves and controls located in the Turbine Building. The EHPM system will normally be powered from offsite power sources, with alternate power available from new, non-safety related DGs. The EHPM pump will take suction from the Condensate Storage Tank (CST) for the respective unit and discharge to the reactor pressure vessel (RPV) via the feedwater lines. The system will be designed to control RPV inventory over a wide range of pressure from safety relief valve (SRV) setpoint (i.e., ~1150 psig) to zero pressure. The system will be capable of operation from a local control station in the turbine building. The option to control the system from the MCR is also under consideration.

Mechanical Design Each EHPM pump will take suction from the respective units CST and have access to the entire volume of the tank (i.e., below the standpipe), similar to the suction path for the High Pressure Coolant Injection (HPCI) and Reactor Core Isolation Cooling (RCIC) pumps. The pumps and piping will be located below the elevation of the CST such that piping is maintained filled by elevation head.

Each EHPM pump will discharge into the reactor feedwater lines downstream of the feedwater pumps, high pressure heaters and upstream of the feedwater check valves. Piping and valves will be provided to allow full flow return to the CST. Flow control valves will be provided to regulate flow to the RPV over a full range of flow and reactor pressure.

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TVA anticipates that the bounding scenario for the hydraulic design of the EHPM pump will be to prevent core damage in the event of loss of all other makeup, up to one SRV spuriously opening and initiation of injection at 20 minutes after a reactor scram.

Electrical Design The EHPM system will be provided with four kilovolts (kV) of power from the respective units 4kV Unit Board C, which in turn is supplied offsite power from the respective Unit Station Service Transformer (USST) or from the Common Station Service Transformer (CSST). Normal and alternate 4 kV power will be supplied to switchgear located near the pump, which will be used to distribute alternating current (AC) power to the system at required voltage levels.

DC control power will be supplied by batteries and battery chargers dedicated to each EHPM system.

Alternate 4 KV power will be supplied to the EHPM switchgear from new DGs capable of providing backup power to all three EHPM pumps, simultaneouslybeing installed as part of the BFN FLEX Integrated Plan. Each EHPM pump will have a separate DG capable of supplying power required for operation of the system.

Instrumentation and Control The EHPM system will be designed with sufficient instrumentation and controls to start and stop the pump, monitor and control flow and discharge pressure, and to transfer power supplies.

Operation of the system will be manual.

Support Systems The EHPM system will be designed to minimize the need for external support systems. The only support currently planned from outside the new EHPM system is 4kV AC power from the AC power distribution system or the alternate supply DGs and water from the condensate storage system. Other typical support such as DC control power, pump and motor cooling, lighting, and heating, ventilation and air conditioning (HVAC) will be dedicated to the system.

Proposed Safe Shutdown Operation The EHPM pump is credited in the Fire PRA to inject water from the CST to the RPV within 20 minutes of the most limiting event to provide core cooling. This timing is related to operation of the pump from local controls in the turbine building. The system is also credited for longer term operation (i.e., four hours) to maintain RPV inventory and to remove decay heat when used in conjunction with the hardened wetwell vent. As discussed in the TVA response to SSA RAI 02 Part e in this enclosure, possible secondary CT fires which could fail the EHPM pump power supply are accounted for in the Fire PRA and the alternate power supply would not be affected.

E3-21

SSA RAI 12 TVA previously responded to SSA RAI 12 by letter dated December 20, 2013 (CNL-13-141). As originally conceived, the design was going to include both the open and close conductor within the braided shield. TVA has determined that a vulnerability exists with the original design concept. Specifically, the design utilized insulated braided shield control power cables, which are to contain wires from both the open and close portions of the motor-operated valve (MOV) control power circuit. Under certain plant conditions, depending on the specific MOV and location of the postulated fire event, one of the two wires within the cable could become energized and therefore become an aggressor source capable of creating a hot short to the other wire inside the cable. Such a short circuit could bypass the protection of the cables external shield and possibly result in spurious valve operation. TVA has revised the design such that only a single MOV control circuit conductor is contained within each braided shield cable.

The below revised response supersedes the previous response for SSA RAI 12 in its entirety.

The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE The 10 Residual Heat Removal (RHR) system valves that are being modified to address spurious opening are:

Valve Number Valve Description 1-FCV-074-0060 RHR SYS I CONTAINMENT SPRAY OUTBD VLV 1-FCV-074-0071 RHR SYSTEM II SUPP POOL VLV 1-FCV-074-0074 RHR SYSTEM II CNTMT SPRAY OUTBD VLV 2-FCV-074-0057 RHR SYS I SUPP POOL SPRAY/TEST ISOL VLV 2-FCV-074-0060 RHR SYS I DRYWELL SPRAY OUTBD VLV 2-FCV-074-0071 RHR SYS II SUPP POOL SPRAY/TEST ISOL VLV 2-FCV-074-0074 DRYWELL SPRAY LINE OUTBOARD CONTAINMENT 3-FCV-074-0057 RHR SYS I SUPP POOL SPRAY/TEST ISOL VLV 3-FCV-074-0060 RHR SYS I CONTAINMENT SPRAY OUTBD VLV 3-FCV-074-0074 RHR SYSTEM II CNTMT SPRAY OUTBD VLV Although the designs for these modifications are not finalized, the current plans are that the modifications will reconfigure the valves control circuits in four major ways, as described below, to reduce the probability of fire-induced spurious opening. Each of these valves utilizes 120 volt (V) AC control power from its own ungrounded control power transformer (CPT).

x The local control station handswitches (HSs) will be removed or abandoned. This aspect of the modification eliminates a target cable vulnerability where fire-induced damage could spuriously open the valve.

x The valve position and torque switches used in the motor contactor circuit will be moved to the neutral side of the motor contactors. With the switches wired in this manner, a postulated single hot short to the limit switch (LS) or torque switch (TS) would not result in spurious opening of the valve.

x Logic relay and valve interlock contacts in the OPEN circuit will be rewired to the hot side of the MCR HS contacts. Once rewired, postulated shorts around the logic relay and interlock contacts would be prevented by the normally open MCR HS contacts from causing spurious valve operation.

x The OPEN contactor circuit conductors between the MCR HS contacts and the motor E3-22

control center (MCC) will be routed in a cable separate from any CPT hot conductors, either in a dedicated raceway or in control power cable trays limited to cables carrying no more than 30 amperes (amps). The new cable will have thermoset insulation and will have an integral, insulated braided shield. The cable shield will be bonded to the CPT neutral, such that a postulated hot short (i.e., inter-cable or ground fault equivalent hot short) would physically make contact with the reference grounded shield, thereby causing electrical protective device clearing, prior to contacting the target circuit conductor that could cause spurious valve operationopening.

The insulated braided shield will be sized so that it is protected by the CPT neutral fuse if routed in a dedicated conduit or the larger of the CPT neutral fuse or a 30 amp protection device if routed in control power cable tray. The new insulated braided shield cable will not be routed in the same fire areas where the cable carrying the valve LS/TS conductors is routed, with the exception of the MCC location fire area.

A conceptual sketch of the modified portion of the circuit design is provided below.

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Fire Modeling (FM) RAI 01, Part b.i TVA previously responded to FM RAI 01, Part b.i, by letter dated December 20, 2013 (CNL-13-141). As described in the revised TVA responses to FPE RAI 10 and FPE RAI 11 in this enclosure, the modifications to install the VEWFDS and gaseous suppression systems into the CSR were deleted. TVA determined that the resulting CSR fire scenarios were too risk significant and refined the scenarios. Part of the refinements use the less conservative cable tray spread timing for thermoset cable trays from NUREG/CR-6850 for thermoplastic cables.

This is recommended by NUREG/CR-7010.

The below revised response supersedes the previous response for FM RAI 01, Part b.i in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

Revised Response The Scoping Fire Modeling analysis assumes that all scenarios involving ignition sources capable of igniting secondary combustibles result in a damaging hot gas layer. All targets in the fire compartment are considered damaged with a severity factor of 1.

Detailed fire modeling calculations to determine time to ignition of secondary combustibles and subsequent flame spread and fire propagation were performed consistent with the processes recommended by NUREG/CR-6850, "Fire PRA Methodology for Nuclear Power Facilities," and NUREG/CR-7010, "Cable Heat Release Ignition, and Spread in Tray Installations During Fire (CHRISTIFIRE) Phase 1: Horizontal Trays." The fire growth and propagation analysis was conducted using the methodology described below.

The time to ignition of a horizontal stack of cable trays was determined by calculating the critical heat release rate (HRR) needed to damage the first (i.e., closest) cable tray in the stack. The critical HRR was determined using FDT 09 or FDT 05.1 and the HRR was manipulated until the temperature or heat flux at the tray location reached the damage criteria. Cable trays were assumed to ignite when the fire reached the critical HRR for damage or if the cable tray was located within the flame with no additional consideration of thermal response. Cables in conduit were not considered to contribute to fire growth or spread.

To calculate the burning area, the entire width of the cable tray was assumed to ignite. The length of the tray assumed to initially ignite was determined by the length of the tray exposed to the fire.

In accordance with NUREG/CR-6850, Section R.4.2, the burning area for horizontal cable trays in a stack was determined using the empirical model for upward flame propagation assuming the angle of horizontal spread from tray level to tray level is 35 degrees to either side.

Horizontal cable tray flame spread rates from NUREG/CR 6850, Section R.4.1.2 were used.

The heat release rates per unit area (HRRPUA) for cables were equal to or exceeded the values recommended by NUREG/CR-7010, Section 9.2.2.

After the first cable tray in a stack of horizontal thermoplastic cable trays was assumed to ignite, the propagation of fire within the stack was assumed to occur at a rate of one tray per minute. If there was a second stack of cable trays adjacent to the first stack, spread to the first (i.e.,

lowest) tray in the second stack was assumed to occur one minute after ignition of the first tray in the first stack.

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For thermoset cable tray stacks, propagation of fire within the stack follows or is more conservative than the timing guidance in NUREG/CR-7010, "Cable Heat Release Ignition, and Spread in Tray Installations During Fire (CHRISTIFIRE) Phase 1: Horizontal Trays" (i.e., FLASH-CAT), which concludes that propagation of a fire within a stack follows the timing outlined in NUREG/CR-6850, Section R.4.2.2 for either thermoplastic or thermoset cables.

Only fire propagation to stacks immediately adjacent to the source have been modeled, in accordance with FAQ 08-0049.

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FM RAI 01, Part b.ii TVA previously responded to FM RAI 01, Part b.ii, by letter dated December 20, 2013 (CNL-13-141). As described in the revised TVA responses to FPE RAI 10 and FPE RAI 11 in this enclosure, the modifications to install the VEWFDS and gaseous suppression systems into the CSR were deleted. TVA determined that the resulting CSR fire scenarios were too risk significant and refined the scenarios. Part of the refinements credit Flamemastic tray coating that is present in the CSR.

LAR Table C-2 has been revised to include Flamemastic as a "Required Fire Protection Feature for Risk" in Fire Zones 25-01 and 16-A, as shown in Enclosure 6 of this letter. LAR Table V-4, "Assessment of Supporting Requirements From Follow-on Peer Review," item FSS-H2, is revised to identify that in addition to self-ignited cable fires, some cable fires caused by welding and cutting have credited Flamemastic, as shown in Enclosure 6 of this letter.

The below revised response supersedes the previous response for FM RAI 01, Part b.ii in its entirety. The changes from the previous response are shown with inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE For self-ignited cable fires and cable fires caused by welding and cutting in the scoping fire modeling analysis, Flamemastic 77 fire protection coating was credited to delay, for 10 minutes, damage to and ignition of cables in cable trays, as allowed by NUREG/CR-6850, Section Q.2.1.

The cables in the initial tray were considered damaged without delay for all self-ignited cable fires and for cable fires due to welding and cutting.

Flamemastic fire protection coating was credited for the transient fires and transient fires caused by welding and cutting in the CSR portion of Fire Compartment 16-A as a result of the risk significance of transient fires. For these scenarios, Flamemastic fire protection coating was credited to delay time for 12 minutes for ignition and 10 minutes for damage. This is consistent with the guidance provided in NUREG/CR-6850, Appendix Q.

Cable trays provided with bottom covers were credited to delay, by 20 minutes, damage to and ignition of thermoset cables as allowed by NUREG/CR-6850, Section Q.2.2. Cable trays provided with bottom covers were also credited to delay, by 4 minutes, damage to and ignition of thermoplastic cables, based on test results from NUREG/CR-0381, "A Preliminary Report on Fire Protection Research Program Fire barriers and Fire retardant Coatings Tests." Fire growth and propagation was not postulated for any fully enclosed cable tray. Cable tray covers were not credited when located within the zone-of-influence (ZOI) of a high hazard event (e.g., high energy arcing faults (HEAFs)).

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FM RAI 01, Part g TVA previously responded to FM RAI 01, Part g, by letter dated February 13, 2014 (CNL-14-020). Based on refinements required to offset risk increases elsewhere, the 10% oil fire scenarios target sets were refined to only include targets in the Zone of Influence (ZOI) rather than whole room damage. Because the target sets for the 10% and 100% are now different, a change to the severity factor (SF) used between the two damage states was required. The use of the SF from NUREG/CR-6850, Appendix E was determined to be appropriate and is used versus the SF in the June 21, 2012, memo from Joseph Gitter to Biff Bradley, "Recent Fire PRA Methods Review Panel Decisions and EPRI 1022993, 'Evaluation of Peak Heat Release Rates in Electrical Cabinets Fires,'" referenced in the February 13, 2014, response for pump fires. The previous sensitivity discussed in the February 13, 2014, response has been updated and is part of the base Fire PRA.

The below revised response supersedes the previous response for FM RAI 01, Part g in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE The following mechanical equipment are located in the Unit 3 cable spreading room (CSR).

x Chilled Water Pumps 3A and 3B which do not contain oil x Control Bay Chillers 3A and 3B which contain lube oil Because Chilled Water Pumps 3A and 3B do not contain lube oil, fires were correctly analyzed by not considering lube oil fire scenarios. The fire modeling analysis, as submitted with the LAR, determined that damage by the oil fire scenarios for Control Bay Chillers 3A and 3B would be bounded by their electrical fires. However, based on further analysis, oil fires for these ignition sources have the potential to create larger fires and therefore, the detailed fire modeling workbook will be updated with these new scenarios.

To determine the effect that these new fire scenarios would have on the Fire PRA, a sensitivity analysis was completed by evaluating these oil fire scenarios. These oil fire scenarios were evaluated following the guidance endorsed by the June 21, 2012, memo from Joseph Gitter to Biff Bradley, "Recent Fire PRA Methods Review Panel Decisions and EPRI 1022993,

'Evaluation of Peak Heat Release Rates in Electrical Cabinets Fires.'" As a conservative approach, to the sensitivity analysis, both the 10% and 100% oil spill fires were assumed to damage all targets in the CSR immediately. The 10% oil fire scenarios were developed using the ZOI for an oil fire resulting from a 10% oil spill. The oil fire severity factors that were used are based on NUREG/CR-6850, Appendix E, Section E.3. The detailed fire modeling analysis and report will behave been updated to include oil fires for these ignition sources and as such, future Fire PRA quantifications will include the results from these oil fire scenarios. The revision to the LAR will be provided to the NRC after the Fire PRA is updated and additional quantification is performed in response to all the NRC RAIs.

These fire modeling updates to the control bay chiller oil spill fire scenarios have been reflected in the updated fire risk results in the TVA response to PRA RAI 24 in of this letter.

The fire risk results of the new oil fire scenarios, with conservative target damage as described above, are provided in Table FM RAI 01.g, in Attachment 1 to this enclosure.

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The results of the sensitivity analysis in Table FM RAI 01.g show that there is a slight increase in the Core Damage Frequency (CDF) and Large Early Release Frequency (LERF) for each unit. Despite the increase, BFN meets the guidance for a Region II plant with total CDF and LERF below 1E-04/reactor year (rx-yr) and 1E-05/rx-yr, respectively, for overall plant risk. BFN also meets the CDF/LERF criteria for a Region II plant, which allows a positive delta (¨)CDF of 1E-05/rx-yr and ¨LERF of 1E-06/rx-yr for acceptable risk increases.

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Probabilistic Risk Assessment (PRA) RAI 01, Part f TVA previously responded to PRA RAI 01, Part f, by letter dated March 14, 2014 (CNL-14-025).

TVA has applied the guidance provided in NUREG/CR-6850, Appendix L to the Main Control Board (MCB) fire scenarios in the updated fire risk results provided in response to PRA RAI 24, Part a (see Enclosure 1 of this letter).

The below revised response supersedes the previous response for PRA RAI 01, Part f in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE A sensitivity analysis that applied theThe guidance in NUREG/CR-6850, Appendix L has been applied to thewas performed to analyze the risk impact that apportioning the full Bin 4 frequency (i.e., 8.24E-04) to each postulated Main Control Board (MCB) fire scenarios such that the full Bin 4 frequency (i.e., 8.24E-04) was applied to each postulated MCB fire scenariowould have on the total fire risk of the Post-Transition (PT) and Compliant (Comp) models for each unit. The location weighting factor was determined to be 1.5, following the guidance in NUREG/CR-6850, Table 6-2. The full Bin 4 frequency multiplied by the location weighting factor (i.e., 1.24E-03) was applied to each MCB fire scenario. All other values neededused to calculate the CDF and LERF (e.g., Probability of Target Damage, Conditional Core Damage Probability (CCDP), Conditional Large Early Release Probability (CLERP)) for the MCB fire scenarios were not affected. The results of this sensitivity analysis are provided in Table PRA RAI 01.f in Attachment 2 to this enclosure.

The results of this sensitivity show a slight increase to the CDF and LERF for each Unit. Despite the increase, BFN meets the guidance for a Region II plant with total CDF and LERF below 1E-04/rx-yr and 1E-05/rx-yr, respectively, for overall plant risk. BFN also meets the change in CDF/LERF criteria for a Region II plant which allows a positive delta (¨) CDF of 1E-05/rx-yr and

¨LERF of 1E-06/rx-yr for acceptable risk increasesThe final disposition of the MCB fire scenarios are reflected in the updated fire risk results that are provided to the NRC in the TVA response to PRA RAI 24, Part a, in Enclosure 1 of this letter.

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PRA RAI 01, Part g TVA previously responded to PRA RAI 01, Part g, by letter dated January 10, 2014 (CNL-14-001). As discussed in the TVA response to FPE RAI 10, TVA has determined that the proposed modification described in LAR Attachment S, Table S-2, Modification 77 to install area wide very early warning fire detection systems in the auxiliary instrument rooms (i.e., Fire Compartments 16-K, 16-M, and 16-O), and discussed in LAR Attachment V,Section V.2.4, will not be installed. In addition, as discussed in the revised TVA responses to FPE RAI 10 and FPE RAI 11 in this enclosure, TVA has determined that the proposed modifications described in Attachment S, Table S-2, Modification 78 to install area wide VEWFDS in the CSRs and Modification 79 to install a new automatic gaseous suppression system in the CSRs, and as discussed in LAR Attachment V,Section V.2.4, will not be installed. Therefore, the sensitivity analyses for these systems are no longer used or discussed in this RAI.

The below revised response supersedes the previous response for PRA RAI 01, Part g in its entirety. The change from the previous response is shown with deleted text struck through and a revision bar in the right margin.

REVISED RESPONSE Quantitative sensitivity analyses were performed after the peer review for some of the fire modeling methods used in the Fire PRA. These are discussed in LAR Attachment V,Section V.2, with additional clarification provided in the LAR Supplement dated May 16, 2013.

The subject of these sensitivity analyses are:

x The use of generic ignition frequencies based upon NUREG/CR-6850, Supplement 1, Chapter 10 x The reduction of the HRR to 69 kW for selected transient fires x The crediting of very early warning fire detection systems (VEWFDS) and automatic suppression for fire scenarios in the Cable Spreading Room and Unit 1 Auxiliary Instrument Rooms For each of the above quantitative sensitivity analyses, BFN met the guidance specified in Regulatory Guide 1.174 for a Region II plant, with total CDF and LERF below 1E-04/reactor (rx)-year (yr) and 1E-05/rx-yr for overall plant risk. BFN also met the CDF/LERF criteria for a Region II plant, which allows a positive CDF of 1E-05/rx-yr and positive LERF of 1E-06/rx-yr for acceptable risk increases with the above sensitivities.

For the remaining sources of uncertainty, additional quantitative analysis of uncertainty intervals does not provide sufficient benefit over a qualitative characterization. Because of the wide range in modeling choices in NUREG/CR-6850, the fire modeling guidance was applied in a conservative manner. Several sources of uncertainty and related assumptions in the fire modeling analysis are discussed in the TVA response to FM RAI 06.a. Additional examples of the conservatisms present in the Fire PRA are:

x The 98th percentile HRR was generally used as the mean value, which would result in an overestimation of fire severity. The ASME/ANS Fire PRA standard requires use of two point fire modeling, and for most risk-significant fires, two points were modeled, one being the severity factor for damage to the ignition source only, and the other for effects beyond the source. For the latter, the 98th percentile was predominately used which conservatively bounds a large range of HRRs. This method results in the use of the 98th percentile HRR for fire damage beyond the source, resulting in conservative target set damage assumptions.

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x NUREG/CR-6850 fire modeling assumptions that involved the growth and propagation of a fire include conservative peak heat release rates, conservative cable flame spread rates, and conservative cable tray propagation rule sets. This directly leads to a reduction in effectiveness of detection/suppression and the time available for manual suppression, and tend to produce conservative estimates of the damage. These conservatisms were implicitly included in the fire damage states.

The quantitative sensitivity analyses that were performed, combined with a qualitative assessment of fire modeling uncertainty, provides sufficient insight into conservatisms of the fire modeling analyses, as well as the effect of input parameter uncertainty on the results of the Fire PRA. The conservatisms in the selection of methods and data associated with NUREG/CR-6850 are expected to outweigh and influence the variability in results more than the parametric data uncertainty. Therefore, meeting Fire Selection Scenario (FSS)-E3 Category I through the use of the current qualitative assessment of fire modeling input parameter uncertainty is sufficient and acceptable for the NFPA 805 application.

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PRA RAI 01.r.01 TVA previously responded to PRA RAI 01.r.01, by letter dated October 6, 2014 (CNL-14-172).

TVA has revised the response to PRA RAI 01.r.01 to clarify that the Fire Compartment frequency in 16-A is actually based on combustible loading, and cable length is only used in the MCR when breaking up fire scenarios based on units. The frequency of the cable fire scenarios in the Unit 1 MCR were divided based on cable tray length and not weighting, which does not follow NUREG/CR-6850. Therefore, the cable fire scenarios analyzed in the Unit 1 MCR assume damage to all cable trays in the Unit 1 MCR. In addition, the response is revised to reflect that TVA has determined that junction box scenarios with risk values greater than 1E-07/yr for CDF and 1E-08/yr for LERF do not need further refinement based on the plant meeting the overall risk objectives.

The below revised response supersedes the previous response for PRA RAI 01.r.01 in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE Response to Part a:

The Fire Probabilistic Risk Analysis (Fire PRA) has some physical analysis units (PAUs) that were evaluated by a single Full Compartment Burn scenario. In the TVA response to PRA RAI 01.r (TVA letter dated December 20, 2013), the first bullet (i.e., Full compartment burn scenarios:) discussion addressed the PAUs that are modeled as full compartment burns. The response to PRA RAI 01.r states in the first bullet discussion, "The ignition frequency for these scenarios was the sum of the contribution from each of the ignition sources assigned to the PAU." The risk contribution of PAUs modeled as full compartment burn scenarios is calculated by multiplying the sum of the frequencies associated with all the ignition sources in the PAU times the conditional core damage probability (CCDP) or conditional large early release probability (CLERP) obtained from failing all the targets mapped to the PAU. These full compartment burn scenarios include the frequency contribution of junction boxes (Bin 18) as apportioned to the PAU.

Each PAU was evaluated based on core damage frequency (CDF) and large early release frequency (LERF) to determine if appropriate risk results were achieved or if detailed fire scenario analysis within the PAU was necessary for risk reduction purposes. PAUs modeled as full compartment burn were not subdivided into multiple scenarios if the resulting PAU CDF and LERF values were lower than 1.0E-08/year (yr) and 1.0E-09/yr, respectively.

Response to Part b:

The difference between the first bullet under "Fire Scenarios" heading and the "Full compartment burn scenarios" heading in the TVA response to PRA RAI 01.r is the level of resolution in the scenario definition. Specifically, the first heading refers to "full compartment burn scenarios." These are PAUs in the Fire PRA where no detailed analysis has been conducted (i.e., multiple fire scenarios within the PAU with separate target sets are not specified for the ignition sources identified in the PAU). The risk contribution of full compartment burn scenarios is calculated as described in the response to Part a of this RAI.

In contrast, the first bullet under the "Fire Scenarios" heading in the TVA response to PRA RAI 01.r refers to the group of PAUs that received more detailed analysis where multiple fire scenarios have been defined and quantified within a PAU. Fire scenarios for the different E3-32

ignition sources identified in the PAU have been quantified, including scenarios associated with junction boxes. There are some PAUs within this group where the target set for junction box or self-ignited cable fires scenarios are the only ignition source within the PAU postulated as full compartment burns. That is, in some PAUs where multiple fire scenarios have been defined and quantified, the risk associated with the junction box and self-ignited cable fires scenarios is calculated by multiplying the ignition frequency of junction box and self-ignited cable fires apportioned to the PAU by the CCDP (or CLERP) resulting from failing all the targets in the PAU. This approach is only performed in PAUs where the resulting risk values are relatively low when compared to scenarios associated with other ignition sources within the PAU.

Response to Part c:

For all PAUs, the fire ignition frequency of the self-ignited cable fires and junction box fires are assigned to the same target sets. Therefore, junction box fires utilize the same CCDP as the self-ignited cable fires. The risk contribution of the junction box fire scenarios is expected to be significantly reduced by the Fire PRA frequently asked question (FAQ) 13-0005 update, as discussed in the TVA response to PRA RAI 19.b.01.a in this enclosure.

Consistent with Fire PRA FAQs 13-0005 and 13-0006, based on risk contribution, the self-ignited cable fires and junction box scenarios are refined by an iterative process to reduce the risk contribution of these scenarios until the risk is low enough to meet the PRA objective. The criteria for determining whether a junction box fire scenario would be evaluated for further refinement is based on meeting the Fire PRA objective of refining scenarios to a CDF of less than or near 1E-07/yr and a LERF or less than or near 1E-08/yr. Scenarios that dodid not meet this criteria have been or will be evaluated further for refinement. In all but a few cases, these scenarios were refined to meet the above scenario risk objective. However, because the overall plant risk objective was met, no additional refinement was deemed necessary for some scenarios.

The iterative approach used is consistent with the quantitative screening guidelines in Chapter 7 of NUREG/CR-6850, "EPRI/NRC-RES Fire PRA Methodology for Nuclear Power Facilities,"

and the screening techniques recommended in FAQ 13-0006, Section 3.2 "Preliminary Analysis" for establishing a conservative CCDP for the first screening level.

For all PAUs, junction box fire scenarios have been modeled in the updated model using one of the following methods:

1. Because of the relatively low frequency of junction boxes and self-ignited cable fires, the CCDP of the full compartment is used as a conservative surrogate for consequences to produce relatively low risk contribution. This is consistent with the general approach of developing a Fire PRA where all targets in a PAU are initially conservatively mapped to all fire scenarios for the purpose of determining if additional fire modeling refinements are necessary.

2. For PAUs where the application of method 1 did not meet the PRA objective, the cable fire and junction box fire scenarios were refined in the updated PRA model by an iterative process to reduce the risk contribution of these scenarios until the risk is not overly conservative. A target set for these scenarios was developed using the zone of influence of a cable tray fire (per the guidance of Appendix R, section R.1 of NUREG/CR-6850). This resulted in multiple trays and/or conduit (depending on the raceway configuration of the PAU) being assumed damaged. This was the guidance available at the time of the License Amendment Request (LAR) development when neither Fire PRA FAQ 13-0005 nor FAQ 13-0006 were available.

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For all PAUs, with the exception of Fire Compartments 16-A and 25-1, this level of refinement, if necessary, is expected to result in sufficiently low risk contribution for junction box fires that meet the PRA objectives, such that further analysis is not warranted.

3. PAU 16-A comprises the Main Control Room (MCR) and the Cable Spreading Room (CSR). In the MCR and the CSR, junction box fire scenarios use the same target sets as the self-ignited cable fire scenarios. The cable fire frequency was apportioned between the MCR and the CSR based on the cable tray lengthcombustible loading ratio within each room. This is consistent with the NUREG/CR-6850, Chapter 6 bin frequency apportionment process.

As described in the TVA response to PRA RAI 17.d (in TVA letter dated February 13, 2014), the cable fire scenarios in the LAR model for the MCR werewithin the MCR, the resultant room cable fire scenario frequency was further subdivided into fire scenarios. These scenarios were assigned a frequency based on the ratio of tray length for each fire scenario. These cable fire scenarios were divided by unit and conservatively assumed to damage to all cable trays located in that units MCR.

However, the PRA model has been updated since the LAR to incorporate the guidance of Fire PRA FAQ 13-0005 for Unit 1 (Units 2 and 3 did not necessitate further refinement). The risk values for these scenarios in the MCR either currently meet the risk objective of being less than or near 1E-07/yr for CDF and 1E-08/yr for LERF, or will behave been evaluated further for refinement.

In the CSR portion of PAU 16-A, junction box fire scenarios also use the same target sets as the self-ignited cable fire scenarios. As with the Unit 1 MCR, tThe PRA model for the CSR has been updated since the LAR to incorporate the guidance of Fire PRA FAQ 13-0005. The scenarios assume that the fire damages one of the top 25 most risk significant cable trays in each unit of the CSR.

Because the target set for each scenario includes at least one cable tray, this is considered bounding of any actual fire damage that could be caused by a junction box fire. Although the target set for scenarios that represent junction box fires in PAU 16-A is conservative, the risk values of these scenarios either currently meet the risk objective of being less than or near 1E-07/yr for CDF and 1E-08/yr for LERF, or will behave been evaluated further for refinement. In all but a few cases, these scenarios were refined to meet the above scenario risk objective. However, because the overall plant risk objective was met, no additional refinement was determined to be necessary for some scenarios. TVA considers this to be appropriate and consistent with the intent of Fire PRA FAQ 13-0006.

4. PAU 25-1 comprises the 550 elevation of the Intake Pumping Station, the Cable Tunnels up to door 440, and the 565 Condenser Circulating Water (CCW) Pump Deck, excluding the A and C Residual Heat Removal Service Water (RHRSW) Rooms. In PAU 25-1, junction box fire scenarios were developed that analyze self-ignited cable fires, and junction box fires.

The target set for these scenarios was developed using the zone of influence of a cable tray fire (per the guidance of Appendix R, section R.1 of NUREG/CR-6850). This was the guidance available at the time of the LAR development, when neither Fire PRA FAQ 13-0005 or FAQ 13-0006 were available. This results in multiple trays and conduit being assumed damaged. Two of the scenarios were limited to a single cable tray due E3-34

to the presence of cable coating material. Using one tray as the target set for these scenarios is consistent with the Fire PRA FAQ 13-0005 process for cable fires.

Because the target set for each scenario includes at least one cable tray, this is considered bounding of any actual fire damage that could be caused by a junction box fire. Although the target set for scenarios that represent junction box fires in PAU 25-1 is conservative, the risk values of these scenarios either currently meet the risk objective of being less than or near 1E-07/yr for CDF and 1E-08/yr for LERF, or will be evaluated further for refinement. TVA considers this to be appropriate and consistent with the intent of Fire PRA FAQ 13-0006, Section 3.2 "Preliminary Analysis" for establishing a conservative CCDP for the first screening level.

Response to Part d:

Although some of the target sets for scenarios that represent junction box fires may be conservative (as detailed in the response to Part c of this RAI), the risk values of these scenarios either currently meet the risk objective of being less than or near 1E-07/yr for CDF and 1E-08/yr for LERF, or will behave been evaluated further for refinement. In all but a few cases, these scenarios were refined to meet the above scenario risk objective. However, since the overall plant risk objective was met, no additional refinement was determined to be necessary for some scenarios. TVA considers this to be appropriate and consistent with the intent of Fire PRA FAQ 13-0006.

The iterative approach used is consistent with the screening techniques recommended in FAQ 13-0006, Section 3.2 "Preliminary Analysis" for establishing a conservative CCDP for the first screening level.

Response to Part e:

With respect to the calculation for junction box frequency, TVA would like to clarify the following:

x The frequency of junction box fires is apportioned using the "PAU" frequency and not "fire zone." The term "fire zone" is a term that is used in FAQ 13-0006 and was an error in the PRA RAI 01.r response. A revised response to PRA RAI 01.r is provided in Enclosure 2 of this letter.

x Consistent with Chapter 6 of NUREG/CR-6850, TVA used a process for apportioning the generic (i.e., plant wide) junction box frequency based on a cable loading ratio in the different PAUs within the scope of the Fire PRA. Chapter 6 of NUREG/CR-6850 recommends on page 6-17 that "The number of junction boxes in an area may be difficult to determine. The frequency can be apportioned based on ratio of cable in the area to the total cable in the plant. Therefore, the ignition source-weighting factor of the cables may be used for this bin, as well." TVA did not identify and count the junction boxes in any PAUs.

x Section 3.1 of FAQ 13-0006 states that the process for apportioning the generic junction box fire ignition frequency based on the amount of cable (e.g., cable loading, number of cables, cable lengths) in the different PAUs within the scope of the Fire PRA remains a valid approach and the clarifications and recommendations presented in the FAQ are alternative methods.

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x In all but two PAUs, the resultant PAU ignition frequency for junction box fires is mapped to a single target set (as discussed above in the response to Part c), and no further frequency adjustment is applied for these PAUs.

x For two PAUs (16-A and 25-1), a frequency adjustment factor was applied to the PAU junction box frequency. This frequency adjustment factor used length of trays within the PAU as a representative ratio of cables and as a surrogate for the ratio of junction boxes. This is discussed in more detail below.

o PAU 16-A comprises the MCR and the CSR. In the MCR and the CSR, junction box fire scenarios use the same target sets as the self-ignited cable fire scenarios. The cable fire frequency was apportioned between the MCR and the CSR based on the cable tray lengthcombustible loading ratio within each room. This is consistent with the Chapter 6 of NUREG/CR-6850 bin frequency apportionment process.

Within the MCR and CSR, the resultant room cable fire scenario frequency was further subdivided into fire scenarios. These scenarios were assigned a frequency based on the ratio of tray length for each fire scenario.

As described in the TVA response to PRA RAI 17.d, the cable fire scenarios in the LAR model for the MCR were divided up by unit and conservatively assumed damage to all cable trays located in that units MCR. However, the PRA model has since been refined to incorporate the guidance of Fire PRA FAQ 13-0005 for Unit 1 (Units 2 and 3 did not necessitate further refinement). For Unit 1, three scenarios were developed and these scenarios now only assume damage to one of the three cable trays for each Unit. The frequency adjustment factor for these three scenarios is based on the ratio of cable length.For consistency between the MCR cable fire scenarios, the Unit 1 cable fire scenarios in the MCR were combined such that they were not divided into three separate scenarios, the Unit 1 MCR cable fire scenario is assumed to damage all cable trays in the Unit 1 MCR. This is consistent with the methodology in the Unit 2 and 3 MCRs. AllThe total cable tray length in the PAU Units 1, 2, and 3 MCRs is included in the denominator of the ratio calculation. The length of the respective tray in each of the three scenarios is the numerator in the ratio calculation. The risk values for these scenarios in the MCR either currently meet the risk objective of being less than or near 1E-07/yr for CDF and 1E-08/yr for LERF, or will behave been evaluated further for refinement.

In all but a few cases, these scenarios were refined to meet the above scenario risk objective. However, because the overall plant risk objective was met, no additional refinement was determined to be necessary for some scenarios.

In the CSR portion of PAU 16-A, junction box fire scenarios use the same target sets as the self-ignited cable fire scenarios. For these scenarios, a frequency adjustment factor was used based on the ratio of cable tray length. A CCDP was calculated for all cable trays in the PAU, however, due to the large number of scenarios only the top 25 most risk significant cable trays in each unit of the CSR were used in the analysis. AllThe total cable tray length in the PAUCSR is included in the denominator of the ratio calculation. The portion of tray in each of the 25 scenarios is the numerator of the ratio calculation. The 25th scenariocable tray with the least risk significance of the top 25 trays includes the remaining cable tray length to capture all cable trays that have a CCDP that is equal to or less than the 25th cable tray CCDPs.

The cable trays and conduits in the CSR portion of PAU 16-A are uniformly distributed throughout the floor area. Therefore, the use of cable tray length as an E3-36

apportioning factor is reasonable. This is consistent with the guidance in Fire PRA FAQ 13-0006. Because the target set for each scenario includes at least one cable tray, this is considered bounding of any actual fire damage that could be caused by a junction box fire. As discussed above, all scenarios are considered bounding of junction box fires.

o In PAU 25-1, junction box fire scenarios use the same target sets as the self-ignited cable fire scenarios. The frequency adjustment factor for these junction box fire scenarios is based on the ratio of cable length. All cable tray length in the PAU is included in the denominator of the ratio calculation. The portion of tray in each of the junction box fire scenarios is the numerator of the ratio calculation.

The target set for these scenarios was developed using the zone of influence of a cable tray fire (per the guidance of Appendix R, section R.1 of NUREG/CR-6850).

This results in multiple trays and conduit being assumed damaged. Two of the scenarios were limited to a single cable tray due to the presence of cable coating material. Using one tray as the target set for these scenarios is consistent with the Fire PRA FAQ 13-0005 process for cable fires.

Because the target set for each scenario includes at least one cable tray, this is considered bounding of any actual fire damage that could be caused by a junction box fire. Because these scenarios combine to incorporate the full junction box PAU frequency, and the targets set are considered bounding of junction box fires for each scenario, the frequency adjustment factor that is based on cable length is not important to junction boxes.

Although the target set for scenarios that represent junction box fires is conservative, the risk values of these scenarios either currently meet the risk objective of being less than or near 1E-07/yr for CDF and 1E-08/yr for LERF, or will behave been evaluated further for refinement.

In all but a few cases, these scenarios were refined to meet the above scenario risk objective. However, because the overall plant risk objective was met, no additional refinement was determined to be necessary for some scenarios. TVA considers this to be appropriate and consistent with the intent of Fire PRA FAQ 13-0006.

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PRA RAI-01, Part v TVA previously responded to PRA RAI 01, Part v, by letter dated March 14, 2014 (CNL-14-025).

TVA has revised its response to PRA RAI 01, Part v to reflect a 1E-06 floor for all Human Failure Event (HFE) combinations that contain Sever Accident Management Guideline (SAMG) actions utilized in the LERF analysis. Please note that in its March 14, 2014 response to PRA RAI 01, Part v, TVA classified Table PRA RAI 01.v-1, "Results of sensitivity study on total fire CDF and LERF," and Table PRA RAI 01.v-2, "Results of sensitivity study on ¨CDF and ¨LERF,"

as security-related information and requested withholding from public disclosure under 10 CFR 2.390. TVA has subsequently determined that the information provided in Table PRA RAI 01.v-1 and Table PRA RAI 01.v-2 is not security-related information. Therefore, this revised response provides markups of both tables.

The below revised response supersedes the previous response for PRA RAI 01, Part v in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE Using a 1E-5 floor for all HFE combinations does not give proper credit to long term decay heat removal (DHR) HFE dependencies in the Level 1 model. Combinations containing those long term DHR HFEs should have a 1E-6 floor for the following reasons. Long term DHR HFEs are those actions associated with using the containment vent to remove decay heat including post vent injection HFEs. Also included are HFEs associated with establishing late suppression pool cooling for DHR. These HFEs occur approximately 10 hours1.157407e-4 days 0.00278 hours 1.653439e-5 weeks 3.805e-6 months to 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months after the reactor scram, whereas most of the other HFEs occur within approximately six hours of the reactor scram. By the time these long term DHR actions are needed, a shift turnover would have occurred and an emergency response organization would have been implemented. A low dependency exists between these long term DHR HFEs and the earlier actions.

In the LERF model, several post core damage actions are cued and guided by the Severe Accident Management Guideline (SAMG) procedures. When these procedures are entered, the command and control of the plant is turned over to the TSC SAM team (Technical Support Center Severe Accident Management). As in the case of the Level 1 DHR HFEs, a low dependency exists between these SAMG actions and the earlier pre-core damage actions. Therefore, a 1E-6 floor for all HFE combinations that contain these SAMG actions is utilized in the LERF analysis.

Even highly qualified and trained teams are subject to confirmation bias and overconfidence. This can cause them to execute an incorrect plan even when ample clues and information exist that indicate their plan is flawed When a new team of qualified experts takes control of the situation, they are much more likely to recognize conditions and problems that were either not recognized or were not considered relevant to the initial team. The subsequent actions of these new teams would reflect the updated thinking and planning and would not be highly dependent on earlier actions by the initial team.

A sensitivity study compared the Fire PRA quantification CDF and LERF metrics for the baseline case that utilized a multiple floor of 1E-71E-5 and 1E-6 with a sensitivity Fire PRA quantification that utilized the aboveonly a 1E-5 and 1E-6 floors. Tables PRA RAI 01.v-1 and PRA RAI 01.v-2 in Attachment 2 to this enclosurebelow provide the results of the sensitivity and E3-38

the values submitted in the LAR. Table PRA RAI 01.v-1 contains the results of the sensitivity study on the total fire CDF and LERF. Table PRA RAI 01.v-2 contains the results of the sensitivity study on the ¨CDF and ¨LERF.

In subsequent Fire PRA quantifications, a joint probability floor of 1E-5 will be used for all CDF combinations that do not include long term DHR HFEs and all LERF combinations that do not include SAMG actions. For CDF combinations that include long term DHR HFEs and LERF combinations that include SAMG actions, a joint probability floor of 1E-6 will be used.

After this change in method is implemented, the affected sections in the LAR will be revised to reflect results of the updated Fire PRA quantifications. The revision to the LAR will be provided to the NRC after the Fire PRA is updated and additional quantification is performed in response to the remaining NRC RAIsThis joint probability floor is reflected in the revised LAR Attachment W results provided in Enclosure 7 of this letter.

Table PRA RAI 01.v-1:

Results of sensitivity study on total fire CDF and LERF CDF LERF W/ One LERF CDF W/ % %

Original HFE Original Unit ChangesOne Increase Increase (Two HFE FloorChange (Two HFE HFE Floor CDF LERF Floors) s Floors) 6.78E-05 6.28E-05 7.96% 2.16E-06 2.14E-06 0.62%

Unit 1 6.78E-05 5.03E-05 34.75% 1.05E-05 5.47E-06 92.87%

7.41E-05 6.59E-05 12.37% 1.90E-06 1.90E-06 0.24%

Unit 2 7.38E-05 5.64E-05 30.84% 1.10E-05 5.37E-06 104.81%

5.89E-05 5.30E-05 11.15% 1.84E-06 1.83E-06 0.07%

Unit 3 7.74E-05 5.92E-05 30.70% 1.08E-05 5.02E-06 115.49%

Table PRA RAI 01.v-2:

Results of sensitivity study on ¨CDF and ¨LERF

¨CDF ¨LERF

¨CDF (Post- ¨LERF (Post-(Post- (Post-transition - transition -

transition - % transition - %

Compliant) Compliant)

Unit Compliant) Increase Compliant) Increase W/ One HFE W/ One HFE Original ¨CDF Original ¨LERF FloorChange FloorChange (Two HFE (Two HFE s s Floors) Floors)

-5.33E-04 -5.37E-04 0.73% 2.00E-07 1.93E-07 3.93%

Unit 1

-1.27E-04 -1.39E-04 8.30% -1.82E-05 -2.24E-05 18.67%

-4.59E-04 -4.67E-04 1.51% 3.01E-08 3.19E-08 -5.73%

Unit 2

-9.86E-05 -1.10E-04 10.60% -1.33E-05 -1.82E-05 26.88%

-5.43E-04 -5.45E-04 0.47% 1.17E-07 1.18E-07 -1.25%

Unit 3

-1.09E-04 -1.21E-04 10.07% -1.36E-05 -1.86E-05 26.76%

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PRA RAI 02 TVA previously responded to PRA RAI 02 by letter dated January 10, 2014 (CNL-14-001). TVA has subsequently determined that the methodology, as discussed in the January 10, 2014, response, was overly conservative and elected to refine the approach to meet PRA objectives.

The below revised response supersedes the previous response for PRA RAI 02 in its entirety.

The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE The fire modeling analysis, which is an input to the Fire PRA, considered transient fires and hot work fires in each fire compartment. For all fire compartments, with the exception of the cable spreading room (CSR) portion of Fire Compartment 16-A, all accessible floor areas were postulated as possible transient and hot work ignition source locations. By analyzing transient fires at all accessible floor areas within these fire compartments, all potential pinch point locations were considered for damage.

Transient and hot work fires were not postulated in locations within PAUs that were considered inaccessible (i.e., where precluded by design). Inaccessible areas are defined as those occupied by permanent fixtures such as plant equipment, structural features, piping, and cable trays. These permanent fixtures must either occupy the floor space entirely or be sufficiently low to the floor (i.e., 2 ft or less), so as to obstruct the placement of transient material.

For the CSR portion of Fire Compartment 16-A, each transient and hot work fire scenario was divided into three damage states based on time to damage and resulting nonsuppression probabilities.

x The first damage state assumes damage to a single cable tray. The cable trays selected are those with the highest Conditional Core Damage Probability (CCDP) in the CSR.

x The second damage state represents unsuccessful suppression after the first damage state, but before the third damage state. The two cable tray combinations selected each have risk significant CCDPs.

x The third damage state represented the unsuccessful suppression after the second damage state. The fire scenario was assumed to spread beyond two cable trays, and conservatively damage all targets in the CSR.

Using this methodology, the entire transient frequency of the CSR was apportioned to risk significant cable trays, which ensured that transient and hot work scenarios were analyzed at risk significant locations.

As discussed in the fire modeling documentation, each transient and hot work fire scenario, analyzed in the CSR portion of Fire Compartment 16-A, assumed damage to one of the cable trays with the highest Conditional Core Damage Probability (CCDP) in the CSR. If damage was considered to spread beyond the tray, the fire scenario conservatively assumed all targets in the CSR were damaged. Using this methodology, the entire transient frequency of the CSR was apportioned to risk significant cable trays, which ensured that transient and hot work scenarios were analyzed at risk significant locations.

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PRA RAI 04, Part c TVA previously responded to PRA RAI 04, Part c, by letter dated February 13, 2014 (CNL-14-020). The TVA response to PRA RAI 04, Part c is revised to reflect that updated abandonment results will be provided as discussed in the TVA response to PRA RAI 04.c.01 (in TVA letter dated October 6, 2014) and to reflect that the final MCR abandonment criteria are stated in the TVA response to PRA RAI 04.01 (in TVA letter dated October 6, 2014).

The below revised response supersedes the previous response for PRA RAI 04, Part c in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE The range of probabilities for properly shutting down the plant is based on the modeling of the HFEs associated with the two shutdown paths, and is calculated on a scenario-specific basis.

The scenario-specific probabilities are calculated based on the operator actions and equipment required to perform the two alternate shutdown strategies. The scenario-specific probability variation is the result of the summation of the human error probabilities (HEPs) for the operator actions (i.e., HFEs) associated with the utilization of the backup control panel 25-32 shutdown path, with the HEPs for the local recovery actions, which is based on the scenario specific fire impacts, and the random failure probabilities of the equipment. This makes the HEPs associated with the local recovery actions scenario-specific. The CCDPs span from 1.73E-03 to 3.51E-01. The CLERPs span from 7.84E-06 to 1.68E-03TVA has prepared a control room abandonment results table as described in the revised TVA response to PRA RAI 04.c.01 (in this enclosure).

The probabilities were applied in the scenario analysis based on an evaluation of whether the scenario would result in MCR abandonment. This is defined and modeled in the Fire PRA as described in the TVA response to PRA RAI 04.01 in TVA letter dated October 6, 2014when the fire damage alone in a scenario leaves no available Nuclear Safety Capability Analysis (NSCA) safe shutdown success path. For loss of habitability scenarios, which were determined by the MCR fire modeling, abandonment was assumed to occur.

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PRA RAI 04.c.01 TVA previously responded to PRA RAI 04.c.01 by letter dated October 6, 2014 (CNL-14-172).

The TVA response to PRA RAI 04.c.01 is revised to reflect changes in the modeling of MCR abandonment.

The below revised response supersedes the previous response for PRA RAI 04.c.01 in its entirety The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE As noted in this RAI, the TVA response to RAI 04.c (in TVA letter dated February 13, 2014) reported a maximum CCDP of 0.351. The response further explained the approach that was used to implement the abandonment modeling in the Fire PRA. That approach was more sophisticated than the majority of Fire PRAs for other licensees because it developed a CCDP for each abandonment scenario based on the specific characteristics of the scenario rather than developing a few CCDPs and applying them to broad bins of scenarios. This latter approach, implemented by most licensees, results in the need to insert some conservatism because the CCDP needs to bound the potential worst case characteristics of the scenarios in the bin, which will be conservative for the other scenarios in the bin. Because the approach used in the BFN Fire PRA considers each abandonment scenario individually, the CCDPs are scenario specific and reflect variables such as fire size and extent of fire damage without having to use a bounding approach.

TVA is currently revisinghas revised the modeling of MCR abandonment as described in the TVA response to PRA RAI 04.01 in this enclosurethe TVA letter dated October 6, 2014. This revision, which is further discussed in our responses to PRA RAI 04.k.01 and PRA RAI 04.l.01, both in this enclosurethe TVA letter dated October 6, 2014, will resulted in changes in the MCR Abandonment CCDPs. In lieu of the modeling construct described in the TVA response to PRA RAI 04.c.01 (in TVA letter dated October 6, 2014), the revised modeling includes an abandonment fault tree that contains logic and basic events for the required HEPs (including a cognitive failure to abandon), HEP dependencies, and equipment failures (both fire-induced and random) that could occur and result in core damage or a large early release. The abandonment model is used to quantify the fire CDF and LERF for the scenarios that meet the criteria stated in the TVA response to PRA RAI 04.01 for loss of control scenarios and the revised TVA response to PRA RAI 04.c, in this enclosure, for loss of habitability scenarios. The revised scenario cutsets contain combinations of the HEPs and equipment failures that contribute to the CCDPs and CLERPs. Based on the results of the revised model, this response is revised to provide the fire CDF and LERF results consistent with the revised model structure and not in the manner described in the TVA response to PRA RAI 04.c.01 in TVA letter dated October 6, 2014. These results represent the integrated risk that includes all failures that contribute to the abandonment scenario.

When the calculation is completed, tThe updated CCDPs will beare provided with the updated risk results as part of the combined/integrated analysis requested in PRA RAI 24, Part a,see of this letter along with an explanation of the CCDP values, as needed. In order to promote a complete understanding of the frequencies of core damage resulting from abandonment cases, there will be four values (one frequency and three probabilities) reported for each case considered, based on the following constructan explanation of how the MCR abandonment scenarios are quantified is provided below.

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Habitability abandonment is modeled to occur with the frequency of the fires that reach the loss of habitability conditions. These frequencies are included in the results table as the Fire Ignition Frequency (FIF) for the habitability scenarios. The scenarios also include target damage from the fire. The abandonment model is quantified and includes required HEPs and equipment failures that might occur. This results in cutsets that include the combinations of the HEPs and equipment failures in the CCDP and CLERP cutsets, so the CCDP and CLERP represent the composite failure probabilities for these scenarios.

Loss of control abandonment is modeled to occur with the frequency of fires that impact targets that result in the loss of control conditions described in the TVA response to PRA RAI 04.01. These frequencies are included in the results table as the FIF for the loss of control scenarios. The abandonment model is quantified and includes required HEPs (including a cognitive failure to abandon) and equipment failures that might occur. This results in cutsets that include the combinations of the HEPs and equipment failures in the CCDP and CLERP cutsets, so the CCDP and CLERP represent the composite failure probabilities for these scenarios.

The revised CCDP results include a new maximum CCDP of 5.83E-01 for a large fire in the cable spreading room or MCR. As with each MCR abandonment scenario, the cutsets were reviewed and the resulting CCDP is justified based on the ability to recover the required equipment for successful shutdown from outside the MCR using the backup control panel and local control switches, which allows recovery of control of equipment for cables damaged in possible fires in fire compartments 16-A, 16-K, 16-M, and 16-O.

The increase in CCDP from the value of 3.51E-01 is primarily due to the inclusion of HEP dependencies and the inclusion of the random failure probabilities for equipment relied on for the backup control panel alternate shutdown path.

The scenario frequencies, abandonment scenario type, CCDPs, CLERPs, CDF, and LERF are provided for each abandonment scenario. The Unit 1 MCR abandonment fire CDF and LERF results are provided in Table 04.c.01-1. The Unit 2 MCR abandonment fire CDF and LERF results are provided in Table 04.c.01-2. The Unit 3 MCR abandonment fire CDF and LERF results are provided in Table 04.c.01-3.

CDF = Fs

CCDP CCDP = CLOHP

CAFP, or CCDP = CLOCP

CAFP Where:

CDF = Core Damage Frequency Fs = Frequency of the Fire Scenario (the frequency that the fire starts in a particular ignition source and affects a particular set of targets based on the scenario)

CCDP = Conditional Core Damage Probability (probability of core damage given the occurrence of the fire scenario)

CLOHP = Conditional Loss of Habitability Probability (probability that the scenario leads to a loss of habitability of the control room, requiring abandonment - applies to fire in the control room only)

CLOCP = Conditional Loss of Control Probability (probability that the scenario leads to a loss of control from the control room, requiring abandonment - applies to fires in the four Control Building areas cited in RAI PRA 04.01).

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CAFP = Conditional Abandonment Failure Probability (probability that achieving safe shutdown fails given that abandonment is required).

For large early release (LER), CDF becomes LERF and CCDP becomes CLERP.

TVA will prepare a control room abandonment results table providing the following information regarding core damage results.

For Loss of Habitability Scenarios:

x The total ignition frequency of the scenarios that have the potential to lead to loss of habitability x The range of CLOHP values for these scenarios x The range of CAFP values for these scenarios x The range of CCDP values for these scenarios x The total CDF for loss of habitability For Loss of Control Scenarios:

x The total frequency of scenarios that can lead to loss of control for three cases:

o Scenarios where the MCR should be abandoned on loss of control, but either the operators fail to abandon or operators fail to shut down the plant successfully, despite of the availability of all of the required equipment outside the MCR (i.e., at the remote shutdown panel or at other locations in the plant) o Scenarios where the MCR is abandoned due to a loss of control and the remote shutdown still fails due to a loss of equipment (either fire-induced or random) that is required to be available for remote shutdown.

o Scenarios where the conditions created by the fire-induced failures are beyond the capability of the alternate shutdown equipment or procedures (i.e., even if the operators follow the abandonment procedure correctly and all the equipment they actuate functions properly, successful shutdown cannot be achieved) x The total frequency of all scenarios that can lead to loss of control. This value is not equal to the sum of the values from the three loss of control abandonment cases mentioned above, because there would be double counting involved. The reason for the double counting is that there is not necessarily a one-to-one correspondence between each scenario and those cases. That is, any given scenario could have two or three possible outcomes if there are failure probabilities involved rather than just direct fire failures (e.g., some cutsets could lead to failure due to human actions, some cutsets could lead to failure due to equipment failures, and some cutsets could lead to failure due to conditions beyond the capability of alternate shutdown). Therefore, that scenario frequency would appear in all three lists.

x The range of CLOCP values across all of these scenarios.

x The range of CAFP values for the first and second cases above.

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o For the first case, the CAFP value for any given scenario will be the sum of the HEPs (or dependent HEP terms) that appear in the cutsets for the scenario, and the range will be the smallest and largest sum across all scenarios.

o For the second case, the CAFP value for any given scenario will be the sum of the equipment failure probabilities (or probabilities of failure combinations) of the equipment required for achieving successful remote shutdown that appear in the cutsets for the scenario. These could be random failures or fire-induced failures. If a cutset exists that contains only direct fire-induced failures (i.e., the fire causes loss of control AND fails a function essential to alternate shutdown), the CAFP would be 1.0.

The range will be the smallest and largest sum across all scenarios.

o For the third case, CAFP is (by definition) 1.0.

x The range of CCDP values for all three cases.

x The total CDF for loss of control for the same three cases, and total for all loss of control scenarios.

The equivalent information will be supplied for Large Early Release.

Given this construct, when a detailed MCR model is fully integrated into the Fire PRA fault trees (as TVA is in the process of doing) CAFP is the metric of interest because it is equivalent to what the plants using a simplified approach have been reporting as the CCDP. TVA will determine whether there are any CAFP values of 1.0 (that is, are there any scenarios at BFN where abandonment is the only way of successfully shutting down the plant, and the conditions are such that following the abandonment procedure will not achieve the goal of avoiding core damage). If there are no scenarios with CAFP values of 1.0, TVA will provide additional detail explaining and justifying why such a result is reasonable.

Updated risk results including the results of this analysis will be provided as part of the combined/integrated results in response to PRA RAI 24 Part a.

E3-45

Table 04.c.01 Unit 1 MCR Abandonment Results 1 1 1 Scenario Scenario FIF CCDP CDF CLERP LERF Type Habitability Abandonment U1 Habitability 5.80E-05 1.76E-01 1.02E-05 2.86E-03 1.66E-07 (Habitability Abandonment with no Unit 1 Spurious SRV Failures) 16-A.3505-TWC-ALL-CSR Control 4.92E-06 5.37E-01 2.64E-06 3.47E-02 1.71E-07 16-A.3005-T-ALL-CSR Control 2.94E-06 5.37E-01 1.57E-06 3.44E-02 1.01E-07 16-A.4001-C-MCR-U1 Control 1.09E-05 1.02E-01 1.11E-06 2.86E-03 3.11E-08 Habitability Abandonment U1 SRV Habitability 1.98E-06 5.37E-01 1.07E-06 3.43E-02 6.81E-08 Failure (Habitability Abandonment with Unit 1 Spurious SRV Failures) 16-A.4501-CWC-MCR-U1 Control 2.94E-06 1.01E-01 2.96E-07 2.80E-03 8.22E-09 16-A.4001-C-CSR-SUPP-1 Control 2.56E-06 8.50E-02 2.17E-07 5.51E-04 1.41E-09 16-A.4001-C-CSR-SUPP-2 Control 5.67E-07 3.21E-01 1.82E-07 3.55E-03 2.02E-09 16-K.013-CAB Control 2.65E-06 3.45E-02 9.17E-08 1.75E-02 4.65E-08 16-K.TS04 Control 8.91E-06 9.89E-03 8.81E-08 3.82E-04 3.40E-09 16-K.TS11 Control 6.99E-06 8.98E-03 6.27E-08 3.78E-04 2.64E-09 16-A.3005-T-CSR-2TRAY-7-9 Control 1.82E-07 3.20E-01 5.82E-08 3.26E-03 5.93E-10 16-A.3005-T-CSR-2TRAY-9 Control 1.71E-07 3.20E-01 5.48E-08 3.24E-03 5.55E-10 16-K.007-CAB Control 1.59E-06 3.43E-02 5.47E-08 1.75E-02 2.79E-08 16-K.009-CAB Control 1.59E-06 3.43E-02 5.47E-08 1.75E-02 2.79E-08 16-K.012-CAB Control 1.59E-06 3.43E-02 5.47E-08 1.75E-02 2.79E-08 16-K.023-CAB Control 1.59E-06 3.43E-02 5.47E-08 1.75E-02 2.79E-08 16-K.024-CAB Control 1.59E-06 3.43E-02 5.47E-08 1.75E-02 2.79E-08 16-A.3005-T-CSR-2TRAY-7-73 Control 1.48E-07 3.32E-01 4.92E-08 2.88E-03 4.27E-10 16-A.3005-T-CSR-2TRAY-73 Control 1.39E-07 3.31E-01 4.62E-08 2.86E-03 3.99E-10 16-K.010-CAB Control 1.06E-06 3.42E-02 3.63E-08 1.75E-02 1.86E-08 16-K.025-CAB Control 1.06E-06 3.42E-02 3.63E-08 1.75E-02 1.86E-08 16-K.026-CAB Control 1.06E-06 3.42E-02 3.63E-08 1.75E-02 1.86E-08 16-A.3005-T-CSR-2TRAY-7-31 Control 1.19E-07 1.56E-01 1.86E-08 1.60E-04 1.90E-11 16-A.3005-T-CSR-2TRAY-7-34 Control 1.19E-07 1.56E-01 1.86E-08 1.60E-04 1.90E-11 16-A.3005-T-CSR-2TRAY-7-35 Control 1.19E-07 1.56E-01 1.86E-08 1.60E-04 1.90E-11 16-A.3005-T-CSR-2TRAY-7-36 Control 1.19E-07 1.56E-01 1.86E-08 1.60E-04 1.90E-11 16-A.3005-T-CSR-2TRAY-7-37 Control 1.19E-07 1.56E-01 1.86E-08 1.60E-04 1.90E-11 16-K.005-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.006-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.008-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.011-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.014-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.015-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.016-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.017-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 E3-46

Table 04.c.01 Unit 1 MCR Abandonment Results 1 1 1 Scenario Scenario FIF CCDP CDF CLERP LERF Type 16-K.018-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.019-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.020-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.021-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.022-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.027-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.028-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.029-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.030-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.031-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.032-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.033-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.034-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.035-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.036-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.037-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-K.038-CAB Control 5.31E-07 3.36E-02 1.79E-08 1.75E-02 9.30E-09 16-A.3005-T-CSR-2TRAY-31 Control 1.12E-07 1.56E-01 1.75E-08 1.60E-04 1.79E-11 16-A.3005-T-CSR-2TRAY-34 Control 1.12E-07 1.56E-01 1.75E-08 1.60E-04 1.79E-11 16-A.3005-T-CSR-2TRAY-35 Control 1.12E-07 1.56E-01 1.75E-08 1.60E-04 1.79E-11 16-A.3005-T-CSR-2TRAY-36 Control 1.12E-07 1.56E-01 1.75E-08 1.60E-04 1.79E-11 16-A.3005-T-CSR-2TRAY-37 Control 1.12E-07 1.56E-01 1.75E-08 1.60E-04 1.79E-11 16-A.3005-T-CSR-2TRAY-7-57 Control 1.62E-07 8.21E-02 1.33E-08 2.06E-04 3.33E-11 16-A.3005-T-CSR-2TRAY-7-58 Control 1.62E-07 8.21E-02 1.33E-08 1.85E-04 2.99E-11 16-A.3005-T-CSR-2TRAY-7-59 Control 1.62E-07 8.21E-02 1.33E-08 1.85E-04 2.99E-11 16-A.3005-T-CSR-2TRAY-7-60 Control 1.62E-07 8.21E-02 1.33E-08 1.85E-04 2.99E-11 16-A.3005-T-CSR-2TRAY-7-61 Control 1.62E-07 8.21E-02 1.33E-08 1.85E-04 2.99E-11 16-A.3005-T-CSR-2TRAY-57 Control 1.52E-07 8.18E-02 1.24E-08 2.03E-04 3.09E-11 16-A.3005-T-CSR-2TRAY-58 Control 1.52E-07 8.18E-02 1.24E-08 1.82E-04 2.77E-11 16-A.3005-T-CSR-2TRAY-59 Control 1.52E-07 8.18E-02 1.24E-08 1.82E-04 2.77E-11 16-A.3005-T-CSR-2TRAY-60 Control 1.52E-07 8.18E-02 1.24E-08 1.82E-04 2.77E-11 16-A.3005-T-CSR-2TRAY-61 Control 1.52E-07 8.18E-02 1.24E-08 1.82E-04 2.77E-11 16-A.3005-T-CSR-SUPP-1 Control 7.61E-08 8.09E-02 6.17E-09 1.36E-04 1.04E-11 16-A.3005-T-CSR-SUPP-2 Control 1.69E-08 3.11E-01 5.27E-09 1.85E-03 3.13E-11 16-A.3005-T-CSR-SUPP-7-1 Control 4.92E-08 7.84E-02 3.85E-09 1.21E-04 5.94E-12 16-A.3005-T-CSR-SUPP-7-2 Control 1.09E-08 3.09E-01 3.37E-09 1.72E-03 1.88E-11 MCA_16-K_17 Control 8.85E-08 3.30E-02 2.92E-09 1.73E-02 1.53E-09 E3-47

Table 04.c.01 Unit 1 MCR Abandonment Results 1 1 1 Scenario Scenario FIF CCDP CDF CLERP LERF Type MCA_16-K_16-L Control 7.86E-08 3.18E-02 2.50E-09 1.72E-02 1.35E-09 16-A.3005-T-CSR-2TRAY-7-47 Control 3.37E-08 5.80E-02 1.95E-09 3.05E-04 1.03E-11 16-A.3005-T-CSR-2TRAY-47 Control 3.17E-08 5.79E-02 1.84E-09 3.05E-04 9.67E-12 16-A.020-VMTR-FRB Control 3.22E-09 4.77E-01 1.54E-09 1.14E-02 3.67E-11 16-A.021-VMTR-FRB Control 3.22E-09 4.77E-01 1.54E-09 1.14E-02 3.67E-11 FS-TRAN-8 Control 9.00E-09 1.58E-01 1.42E-09 2.75E-05 2.48E-13 FS-TRAN-30 Control 6.88E-09 1.24E-02 8.55E-11 2.31E-04 1.59E-12 Note 1: The actual calculation may carry more digits than shown in this table, which may result in rounding differences in the FIFs, CDFs, and LERFs. The FIF is the product of the ignition frequency, severity factor, and non-suppression probability for the scenario.

E3-48

Table 04.c.01 Unit 2 MCR Abandonment Results 1 1 1 Scenario Scenario FIF CCDP CDF CLERP LERF Type Habitability Abandonment U2 Habitability 5.81E-05 2.48E-01 1.44E-05 3.72E-03 2.16E-07 (Habitability Abandonment with no Unit 2 Spurious SRV Failures) 16-A.3505-TWC-ALL-CSR Control 4.92E-06 5.83E-01 2.87E-06 3.33E-02 1.64E-07 16-A.3005-T-ALL-CSR Control 2.94E-06 5.83E-01 1.71E-06 3.30E-02 9.67E-08 Habitability Abandonment U2 SRV Habitability 1.95E-06 5.83E-01 1.14E-06 3.28E-02 6.40E-08 Failure (Habitability Abandonment with Unit 2 Spurious SRV Failures) 16-A.4001-C-CSR-SUPP-1 Control 2.56E-06 3.42E-01 8.74E-07 4.05E-03 1.03E-08 16-M.TS05 Control 9.88E-06 1.43E-02 1.42E-07 1.94E-03 1.92E-08 16-M.TS10 Control 7.91E-06 1.52E-02 1.20E-07 1.26E-03 9.98E-09 16-M.013-CAB Control 2.65E-06 3.26E-02 8.66E-08 1.86E-02 4.94E-08 16-A.3005-T-CSR-2TRAY-7-15 Control 1.63E-07 3.83E-01 6.24E-08 4.10E-03 6.68E-10 16-A.3005-T-CSR-2TRAY-7-57 Control 1.62E-07 3.73E-01 6.03E-08 3.38E-03 5.47E-10 16-A.3005-T-CSR-2TRAY-7-60 Control 1.62E-07 3.73E-01 6.03E-08 3.41E-03 5.51E-10 16-A.3005-T-CSR-2TRAY-15 Control 1.53E-07 3.83E-01 5.87E-08 4.08E-03 6.25E-10 16-A.3005-T-CSR-2TRAY-57 Control 1.52E-07 3.73E-01 5.68E-08 3.37E-03 5.13E-10 16-A.3005-T-CSR-2TRAY-60 Control 1.52E-07 3.73E-01 5.68E-08 3.39E-03 5.16E-10 16-A.3005-T-CSR-2TRAY-7-58 Control 1.62E-07 3.40E-01 5.50E-08 3.29E-03 5.32E-10 16-A.3005-T-CSR-2TRAY-7-59 Control 1.62E-07 3.40E-01 5.50E-08 3.29E-03 5.32E-10 16-A.3005-T-CSR-2TRAY-7-61 Control 1.62E-07 3.40E-01 5.50E-08 3.29E-03 5.32E-10 16-A.3005-T-CSR-2TRAY-7-16 Control 1.56E-07 3.33E-01 5.20E-08 3.22E-03 5.03E-10 16-A.3005-T-CSR-2TRAY-7-45 Control 1.56E-07 3.33E-01 5.20E-08 3.22E-03 5.03E-10 16-A.3005-T-CSR-2TRAY-7-73 Control 1.48E-07 3.51E-01 5.20E-08 3.24E-03 4.80E-10 16-A.3005-T-CSR-2TRAY-58 Control 1.52E-07 3.39E-01 5.16E-08 3.28E-03 4.99E-10 16-A.3005-T-CSR-2TRAY-59 Control 1.52E-07 3.39E-01 5.16E-08 3.28E-03 4.99E-10 16-A.3005-T-CSR-2TRAY-61 Control 1.52E-07 3.39E-01 5.16E-08 3.28E-03 4.99E-10 16-M.008-CAB Control 1.59E-06 3.23E-02 5.15E-08 1.86E-02 2.96E-08 16-M.009-CAB Control 1.59E-06 3.23E-02 5.15E-08 1.86E-02 2.96E-08 16-M.012-CAB Control 1.59E-06 3.23E-02 5.15E-08 1.86E-02 2.96E-08 16-M.022-CAB Control 1.59E-06 3.23E-02 5.15E-08 1.86E-02 2.96E-08 16-M.023-CAB Control 1.59E-06 3.23E-02 5.15E-08 1.86E-02 2.96E-08 16-A.3005-T-CSR-2TRAY-16 Control 1.47E-07 3.33E-01 4.89E-08 3.21E-03 4.72E-10 16-A.3005-T-CSR-2TRAY-45 Control 1.47E-07 3.33E-01 4.89E-08 3.21E-03 4.72E-10 16-A.3005-T-CSR-2TRAY-73 Control 1.39E-07 3.50E-01 4.88E-08 3.22E-03 4.49E-10 16-A.3005-T-CSR-2TRAY-7-31 Control 1.19E-07 3.83E-01 4.56E-08 3.28E-03 3.90E-10 16-A.3005-T-CSR-2TRAY-7-34 Control 1.19E-07 3.83E-01 4.56E-08 3.28E-03 3.90E-10 16-A.3005-T-CSR-2TRAY-7-35 Control 1.19E-07 3.83E-01 4.56E-08 3.28E-03 3.90E-10 16-A.3005-T-CSR-2TRAY-7-36 Control 1.19E-07 3.83E-01 4.56E-08 3.28E-03 3.90E-10 16-A.3005-T-CSR-2TRAY-7-37 Control 1.19E-07 3.83E-01 4.56E-08 3.28E-03 3.90E-10 E3-49

Table 04.c.01 Unit 2 MCR Abandonment Results 1 1 1 Scenario Scenario FIF CCDP CDF CLERP LERF Type 16-A.3005-T-CSR-2TRAY-7-68 Control 1.63E-07 2.76E-01 4.49E-08 3.24E-03 5.28E-10 16-A.3005-T-CSR-2TRAY-31 Control 1.12E-07 3.83E-01 4.29E-08 3.25E-03 3.64E-10 16-A.3005-T-CSR-2TRAY-34 Control 1.12E-07 3.83E-01 4.29E-08 3.25E-03 3.64E-10 16-A.3005-T-CSR-2TRAY-35 Control 1.12E-07 3.83E-01 4.29E-08 3.25E-03 3.64E-10 16-A.3005-T-CSR-2TRAY-36 Control 1.12E-07 3.83E-01 4.29E-08 3.25E-03 3.64E-10 16-A.3005-T-CSR-2TRAY-37 Control 1.12E-07 3.83E-01 4.29E-08 3.25E-03 3.64E-10 16-A.3005-T-CSR-2TRAY-68 Control 1.53E-07 2.76E-01 4.23E-08 3.23E-03 4.95E-10 16-M.006-CAB Control 1.06E-06 3.20E-02 3.40E-08 1.86E-02 1.98E-08 16-M.010-CAB Control 1.06E-06 3.20E-02 3.40E-08 1.86E-02 1.98E-08 16-M.024-CAB Control 1.06E-06 3.20E-02 3.40E-08 1.86E-02 1.98E-08 16-M.025-CAB Control 1.06E-06 3.20E-02 3.40E-08 1.86E-02 1.98E-08 16-A.3005-T-CSR-SUPP-1 Control 7.61E-08 3.39E-01 2.58E-08 3.06E-03 2.33E-10 16-A.3005-T-CSR-SUPP-7-1 Control 4.92E-08 3.39E-01 1.66E-08 2.65E-03 1.30E-10 16-M.007-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.011-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.014-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.015-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.016-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.017-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.018-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.019-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.020-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.021-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.026-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.027-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.028-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.029-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.030-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.031-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.032-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.033-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.034-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.035-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.036-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.037-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.038-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 16-M.039-CAB Control 5.31E-07 3.11E-02 1.65E-08 1.78E-02 9.46E-09 E3-50

Table 04.c.01 Unit 2 MCR Abandonment Results 1 1 1 Scenario Scenario FIF CCDP CDF CLERP LERF Type MCA_16-M_18 Control 7.91E-08 1.86E-01 1.47E-08 1.75E-02 1.38E-09 16-A.3005-T-CSR-2TRAY-7-22 Control 1.17E-07 6.38E-02 7.45E-09 5.04E-04 5.89E-11 16-A.3005-T-CSR-2TRAY-7-25 Control 1.17E-07 6.38E-02 7.45E-09 5.04E-04 5.89E-11 16-A.3005-T-CSR-2TRAY-7-26 Control 1.17E-07 6.38E-02 7.45E-09 5.04E-04 5.89E-11 16-A.3005-T-CSR-2TRAY-7-28 Control 1.17E-07 6.38E-02 7.45E-09 5.04E-04 5.89E-11 16-A.3005-T-CSR-2TRAY-7-30 Control 1.17E-07 6.38E-02 7.45E-09 5.04E-04 5.89E-11 16-A.3005-T-CSR-2TRAY-22 Control 1.10E-07 6.37E-02 7.00E-09 4.97E-04 5.46E-11 16-A.3005-T-CSR-2TRAY-25 Control 1.10E-07 6.37E-02 7.00E-09 4.97E-04 5.46E-11 16-A.3005-T-CSR-2TRAY-26 Control 1.10E-07 6.37E-02 7.00E-09 4.97E-04 5.46E-11 16-A.3005-T-CSR-2TRAY-28 Control 1.10E-07 6.37E-02 7.00E-09 4.97E-04 5.46E-11 16-A.3005-T-CSR-2TRAY-30 Control 1.10E-07 6.37E-02 7.00E-09 4.97E-04 5.46E-11 16-A.3005-T-CSR-2TRAY-7-6 Control 3.04E-08 5.53E-02 1.68E-09 1.46E-04 4.43E-12 16-A.3005-T-CSR-2TRAY-6 Control 2.86E-08 5.51E-02 1.57E-09 1.24E-04 3.54E-12 16-A.020-VMTR-FRB Control 3.22E-09 4.54E-01 1.46E-09 1.12E-02 3.61E-11 16-A.021-VMTR-FRB Control 3.22E-09 4.54E-01 1.46E-09 1.12E-02 3.61E-11 MCA_16-M_16-L Control 1.16E-08 2.70E-02 3.13E-10 1.66E-02 1.93E-10 FS-TRAN-19 Control 6.88E-09 9.59E-03 6.61E-11 7.74E-04 5.33E-12 FS-TRAN-43 Control 6.88E-09 9.59E-03 6.61E-11 7.74E-04 5.33E-12 Note 1: The actual calculation may carry more digits than shown in this table, which may result in rounding differences in the FIFs, CDFs, and LERFs. The FIF is the product of the ignition frequency, severity factor, and non-suppression probability for the scenario.

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Table 04.c.01 Unit 3 MCR Abandonment Results 1 1 1 Scenario Scenario FIF CCDP CDF CLERP LERF Type Habitability Abandonment U3 Habitability 3.91E-05 2.77E-01 1.09E-05 5.71E-03 2.24E-07 (Habitability Abandonment with no Unit 3 Spurious SRV Failures)

Habitability Abandonment U3 SRV Habitability 2.09E-05 4.95E-01 1.03E-05 2.85E-02 5.95E-07 Failure (Habitability Abandonment with Unit 3 Spurious SRV Failures) 16-A.3505-TWC-ALL-CSR Control 4.92E-06 4.95E-01 2.43E-06 2.83E-02 1.39E-07 16-A.3005-T-ALL-CSR Control 2.94E-06 4.94E-01 1.45E-06 2.79E-02 8.18E-08 16-A.020-VMTR-A Control 5.36E-06 1.74E-01 9.33E-07 2.34E-03 1.25E-08 16-A.021-VMTR-A Control 5.36E-06 1.74E-01 9.33E-07 2.34E-03 1.25E-08 16-O.TS09 Control 7.64E-06 4.59E-02 3.51E-07 4.12E-03 3.15E-08 16-O.TS06 Control 7.64E-06 4.49E-02 3.43E-07 2.85E-03 2.18E-08 16-O.015-CAB Control 2.65E-06 6.39E-02 1.70E-07 1.92E-02 5.10E-08 16-O.011-CAB Control 1.59E-06 6.34E-02 1.01E-07 1.89E-02 3.01E-08 16-O.014-CAB Control 1.59E-06 6.34E-02 1.01E-07 1.89E-02 3.01E-08 16-O.024-CAB Control 1.59E-06 6.34E-02 1.01E-07 1.89E-02 3.01E-08 16-O.025-CAB Control 1.59E-06 6.34E-02 1.01E-07 1.89E-02 3.01E-08 16-O.009-CAB Control 1.06E-06 6.30E-02 6.69E-08 1.88E-02 2.00E-08 16-O.012-CAB Control 1.06E-06 6.30E-02 6.69E-08 1.88E-02 2.00E-08 16-O.026-CAB Control 1.06E-06 6.30E-02 6.69E-08 1.88E-02 2.00E-08 16-O.027-CAB Control 1.06E-06 6.30E-02 6.69E-08 1.88E-02 2.00E-08 16-O.003-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.004-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.005-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.006-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.007-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.008-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.010-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.013-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.016-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.017-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.018-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.019-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.020-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.021-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.022-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.023-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.028-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.029-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.030-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 E3-52

Table 04.c.01 Unit 3 MCR Abandonment Results 1 1 1 Scenario Scenario FIF CCDP CDF CLERP LERF Type 16-O.031-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.032-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.033-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.034-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.035-CAB Control 5.31E-07 6.19E-02 3.29E-08 1.78E-02 9.46E-09 16-O.4001-C Control 4.92E-06 5.56E-03 2.74E-08 1.19E-04 5.86E-10 16-A.3005-T-CSR-2TRAY-7-1 Control 6.85E-08 2.66E-01 1.82E-08 1.46E-03 1.00E-10 16-A.3005-T-CSR-2TRAY-1 Control 6.44E-08 2.65E-01 1.71E-08 1.45E-03 9.35E-11 MCA_16-O_16-N Control 1.59E-08 3.49E-01 5.56E-09 1.74E-02 2.77E-10 MCA_16-O_19 Control 6.77E-08 5.75E-02 3.89E-09 1.72E-02 1.16E-09 16-A.020-VMTR-FRB Control 3.22E-09 3.22E-01 1.04E-09 1.04E-02 3.35E-11 16-A.021-VMTR-FRB Control 3.22E-09 3.22E-01 1.04E-09 1.04E-02 3.35E-11 FS-TRAN-81 Control 7.57E-09 2.69E-02 2.04E-10 8.57E-04 6.49E-12 FS-TRAN-88 Control 7.57E-09 1.19E-02 9.01E-11 9.10E-04 6.89E-12 FS-TRAN-71 Control 1.44E-08 5.69E-03 8.19E-11 9.10E-04 1.31E-11 Note 1: The actual calculation may carry more digits than shown in this table, which may result in rounding differences in the FIFs, CDFs, and LERFs. The FIF is the product of the ignition frequency, severity factor, and non-suppression probability for the scenario.

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PRA RAI 04, Part d TVA previously responded to PRA RAI 04, Part d, by letter dated February 13, 2014 (CNL-14-020). The TVA response to PRA RAI 04, Part d is revised to reflect that TVA now determines LERF for abandonment scenarios by utilizing the Fire PRA LERF fault tree with credit for operator actions required for abandonment as described in the TVA response to PRA RAI 04.01 (in TVA letter dated October 6, 2014).

The below revised response supersedes the previous response for PRA RAI 04, Part d in its entirety The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE LERF wasis determined for abandonment scenarios by multiplying the frequency and CCDP of the scenario by the HEP for the event HFFA0064PCICLOSE. This event represents the operator action to vent the control air supply to containment isolation valves, which failed the containment isolation valves closed. The modification that enables this function is described in LAR Attachment S, Table S-2, Modification 93utilizing the Fire PRA LERF fault tree with credit for operator actions for abandonment as described in the TVA response to PRA RAI 04.01 (in TVA letter dated October 6, 2014).

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PRA RAI 04, Part e TVA previously responded to PRA RAI 04, Part e, by letter dated February 13, 2014 (CNL-14-020). The TVA response to PRA RAI 04, Part e is revised to reflect that the final MCR abandonment criteria are stated in the TVA response to PRA RAI 04.01 (in TVA letter dated October 6, 2014).

The below revised response supersedes the previous response for PRA RAI 04, Part e in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE MCR abandonment decisions are based on one of two cues. The first cue is a significant reduction of MCR habitability due to the fire effects such as smoke or heat. Fire modeling is used to determine the ignition sources (initiators) and fire severities that would cue control room abandonment due to MCR habitability issues. A fire scenario and frequency is established for each MCR initiator that meets the cue criteria and abandonment is assumed for this scenario.

The second cue is an MCR fire scenario that results in a loss of control. Functionality abandonment occurs when the fire damage alone in a scenario leaves no available safe shutdown success path. In these scenarios, it is assumed that operators would abandon the control room and use ex-control room alternative shutdown procedures. In order to identify those scenarios that result in this level of equipment damage, each scenario in the affected fire compartments for each unit was evaluated without crediting the EHPM pump modification. If the resulting cutsets based on review showed no safe shutdown path was available, then the use of alternative shutdown would be required. Both of these abandonment scenario types are represented in the Fire PRA model. The Fire PRA model assumed that the control room supervisor would make the decision to abandon based on observed MCR conditions or plant conditions that are similar to those discussed aboveFunctionality abandonment is described in the TVA response to PRA RAI 04.01 (in TVA letter dated October 6, 2014).

The considerations for the decision to abandon will be addressed by the post-transition fire procedures and will be based upon Senior Reactor Operator (SRO) judgment that physical occupation is no longer feasible or the equipment needed to safely shut down the plant is not available in the particular unit's MCR. The modeling of the conditions that cue the decision to abandon will be refined once the procedure is complete, as required by LAR Attachment S, Table S-3, Implementation Item 33.

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PRA RAI 04, Part g TVA previously responded to PRA RAI 04, Part g, by letter dated February 13, 2014 (CNL-14-020). The TVA response to PRA RAI 04, Part g is revised to reflect that the final MCR abandonment criteria are stated in the TVA response to PRA RAI 04.01, o4.c.01, and 04.k.01 (in TVA letter dated October 6, 2014).

The below revised response supersedes the previous response for PRA RAI 04, Part g in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE The cues for entry into the Compartment 16 Safe Shutdown Instruction (SSI) abandonment section were modeled as either loss of control or loss of a habitable MCR environment due to fire effects. Because of the obvious and severe nature of the abandonment cues, the PRA model assumed that the operators would abandon the MCR when these cues are present.

While the operators may need to make some decisions during the cognitive stage of the abandonment actions, the need for the actions is primarily recognized by being in and following the abandonment SSI. The individual abandonment HFEs associated with the key SSI steps were dominated by the execution errors; cognitive errors and cognitive timing were not considered. Errors associated with omitting procedure steps are considered in the execution portion of the analysisFunctionality abandonment including cognitive error and cues is described in the TVA responses to PRA RAI 04.01, PRA RAI 04.c.01, and PRA RAI 04.k.01 (in TVA letter dated October 6, 2014).

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PRA RAI 04, Part k TVA previously responded to PRA RAI 04, Part k, by letter dated February 13, 2014 (CNL-14-020). The TVA response to PRA RAI 04, Part k is revised to reflect the TVA response to PRA RAI 04.k.01 (in TVA letter dated October 6, 2014). In addition, the response is revised to clarify that condensate flood-up is credited in the MCR abandonment model as an initial injection source for scenarios that involve an open Safety Relief Valve (SRV).

The below revised response supersedes the previous response for PRA RAI 04, Part k in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE For alternative shutdown, there are two independent shutdown paths credited: the backup control panel shutdown path and the EHPM pump shutdown path. The backup control panel shutdown path uses RCIC and LPCI for injection and SPC or Alternate Shutdown Cooling (ASDC) for decay heat removal. Inventory control and pressure control are also required to achieve safe shutdown with this path. For the EHPM pump path, operation of the EHPM pump assures core cooling for inventory control. Long term decay heat removal is accomplished by use of the hardened wetwell vent. The two paths are modeled as independent and utilization of one path does not have a detrimental effect on the other path because the EHPM pump can inject at both high and low pressure. Because of this assumption, dependencies between actions to initiate RCIC and LPCI and actions to initiate the EHPM pump were not considered.

Long term decay heat removal can be established by either SPC, ASDC, or the hardened wetwell vent. Based on existing MAAP analysis, the wetwell vent is not required until 12 or more hours after the reactor scram. By this time the emergency response organization would be staffed and providing support to the operations crew. Therefore, the Fire PRA assumed there would be no dependency between these actions. For abandonment scenarios involving open SRVs, only one shutdown path utilizingeither Residual Heat Removal (RHR) or Condensate are credited as an initial injection source was credited. Therefore, there are no potential dependencies associated with this pathAs discussed in the TVA response to PRA RAI 04.k.01 (in TVA letter dated October 6, 2014), HRA dependencies are evaluated to ensure that any contribution, however negligible, is included in the risk results.

The two alternate shutdown pathways are independent in nature and no action taken on one path can adversely affect the other. This will be verified when the new SSIsFire Safe Shutdown Procedures are validated prior to implementation.

LAR Attachment S, Table S-3, Implementation Items 32 and 33 address the requirement to update both the Fire PRA and HRA analyses to reflect the effects of the finalized modifications and procedures, which include the Fire Area 16 SSIFire Safe Shutdown Procedures.

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PRA RAI 04, Part l TVA previously responded to PRA RAI 04, Part l, by letter dated February 13, 2014 (CNL-14-020). The TVA response to PRA RAI 04, Part l is revised to clarify that all random equipment failures have been included for MCR abandonment as described in the TVA response to PRA RAI 04.l.01 (in TVA letter dated October 6, 2014).

The below revised response supersedes the previous response for PRA RAI 04, Part l in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE HEPs are assumed to be significantly greater than equipment failure probabilities for the backup control shutdown path. Therefore, hardware failure probabilities for the backup control panel shutdown path were ignored in the calculation of CDF and LERF. The HEP total is approximately 0.1, which is above nominal equipment failure probabilities of the equipment used for safe shutdown. Equipment failure probabilities are included for the EHPM pump and hardened wetwell vent shutdown path.

As stated in the resolution for Facts and Observations (F&O) 7-16 in LAR Attachment V, given that the mean values of hardware failures and their associated uncertainties are small in comparison with those associated with the HFEs for MCR abandonment, this exclusion is deemed acceptable from an overall risk perspective.As discussed in the TVA response to PRA RAI 04.l.01 (in TVA letter dated October 6, 2014), TVA incorporated the previously excluded random equipment failures that could affect the ability to achieve safe shutdown following abandonment. This includes the fire-induced failures of the shutdown panel itself as well as the random and fire induced failure of the equipment operated from the panel or locally in the field as part of the abandonment shutdown process that would affect the safe shutdown path.

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PRA RAI 05 TVA previously responded to PRA RAI 05 by letter dated March 14, 2014 (CNL-14-025).

Following submittal of TVA letter CNL-14-025, several methodologies and approaches were revised in the BFN Fire PRA which changed or eliminated some deviations from NUREG/CR-6850. Enclosure 6 of this letter provides the non security-related marked up pages showing the changes to LAR, Attachment V, "Fire PRA Quality," described in the revised response.

The below revised response supersedes the previous response for PRA RAI 05 in its entirety.

The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE As noted in LAR Section 4.5.1.2, the process for creation of the Fire PRA model and quantification of that model used a methodology consistent with the guidance provided in NUREG/CR-6850 and subsequent clarifications documented in responses to NFPA 805 FAQs.

Deviations from NUREG/CR-6850 that were utilized in the Fire PRA model development are documented in LAR Attachment V.

The results of the sensitivity studies for these deviations are provided in LAR Attachment V.

These deviations and sensitivities, with the exception of the deviation discussed in LAR Section V.2.3, are not related to the guidance from the June 21, 2012, memo from NRC to NEI, "Recent Fire PRA Methods review Panel Decisions and EPRI 1022993, 'Evaluation of Peak Heat Release Rates in Electrical Cabinets Fires'" (hereinafter referred to as "the June 21 memo"). A discussion of the reduced transient heat release rates can be found in the TVA response to PRA RAI 16 (in the TVA letter dated February 13, 2014). The deviations and sensitivities discussed in LAR Attachment V are listed below and additional clarification is provided for any related changes.

1. LAR Section V.2.2 - "Generic Ignition Frequency Sensitivity Analysis" to support the use of updated generic fire frequencies arising from the industry review of fire events.

2. LAR Section V.2.3 - "Use of 69kW Heat Release Rate Used for Selected Transient Fires."

3. LAR Section V.2.4 - "Credit for very early warning fire detectors (VEWFDs) and Automatic Suppression for Fire Scenarios in Cable Spreading Room and Unit 1 Auxiliary Instrument Room." As discussed in the revised TVA responses to FPE RAI 10 and FPE RAI 11 (in this enclosure), TVA has determined that the proposed modifications described in Attachment S, Table S-2, Modification 78 to install area wide very early warning fire detection systems in the CSRs and Modification 79 to install a new automatic gaseous suppression system in the CSRs, and as discussed in LAR Attachment V,Section V.2.4, will not be installed. Therefore, there is no deviation from approved methodTVA has applied a prompt detection credit for area wide very early warning fire detection systems in the Unit 1 Auxiliary Instrument Room and the CSRs.

a. The area wide very early warning fire detection system is no longer being installed in the Auxiliary Instrument Rooms (See FPE RAI 10). A sensitivity study was performed, as documented in the TVA response to FPE RAI 12, Part c (in this enclosure), to analyze the effect of removing the prompt detection credit.

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b. A sensitivity study was performed for the area wide very early warning fire detection system in the CSRs that is detailed in LAR Section V.2.4.

4. LAR Section V.2.5 - "Credit for Electrical Raceway Fire Barrier Systems (ERFBS) that are installed in accordance with NFPA 805 Chapter 3 Section 3.11.5." As discussed in the response to FPE RAI 5 (in the TVA letter dated January 10, 2014), this deviation has been removed. TVA has re-considered the use of Engineering Equivalency Evaluations for this application and decided not to disposition 1-hour ERFBS without automatic suppression as adequate for the hazard. The current plan for these applications is to install 1-hour ERFBS and to resolve the Variance from Deterministic Requirements using the fire risk evaluation process.

TVA haspreviously identified the following items as deviations that are not addressed in LAR Attachment Vin its response to PRA RAI 05 (in TVA letter dated March 14, 2014). However, due to the changes in the methodology of these items, listed below, TVA no longer considers these items to be deviations from NUREG/CR-6850.

1. The TVA response to PRA RAI 01.f (in this enclosureTVA letter dated March 14, 2014) addresses the apparent deviations noted in the RAI for F&O 2-54. The TVA response to PRA RAI 01.f provides the results of a sensitivity studyAs stated in the revised response to PRA RAI 01, Part f (in this enclosure), the treatment of MCR fire scenarios has been revised to apply the full Bin frequency to each of the postulated MCB fire scenarios and a location weighting factor of 1.5 was determined using the guidance in NUREG/CR-6850. Therefore, treatment of MCB fires in the BFN Fire PRA is no longer considered a deviation.

2. The catastrophic turbine/generator (T/G) fire postulated for PAU 26A is not consistent with Table O-2 of NUREG/CR-6850. The TVA response to PRA RAI 01.h, Part ii (in Enclosure 2 of this letter) provides the results of a sensitivity analysisThe frequency and severity factor of catastrophic turbine generator fires has been revised and is included in the composite analysis provided in the TVA response to PRA RAI 24, Part a (in Enclosure 1 of this letter) and the PRA that will be used at the beginning of the self-approval of post-transition changes.

3. The dependency analysis was not performed between non-LERF and LERF actions.

The TVA response to PRA RAI 01.o (in this enclosure) states that in subsequent Fire PRA quantifications, the HRA will consider LERF HFE dependenciesDependency between LERF and CDF actions is included in the composite analysis provided in the TVA response to PRA RAI 24, Part a (in Enclosure 1 of this letter) and the PRA that will be used at the beginning of the self-approval of post-transition changes.

4. It is unclear whether those ignition sources that do not result in any scenarios that propagate to secondary targets were maintained in the analysis to reflect the fire-induced failure of the ignition source itself. The TVA response to PRA RAI 01.s (in TVA letter dated February 13, 2014) states that non-propagating scenarios that were originally screened have been identified and will be entered into SAFE-PB and quantified to include the risk contribution into the Fire PRAThe quantitative screening criteria has been updated to be consistent with the criteria in NUREG/CR-6850 Task 7 and non-propagating fire scenarios that do not screen are included in the composite analysis provided in the TVA response to PRA RAI 24, Part a (in Enclosure 1 of this letter) and the PRA that will be used at the beginning of the self-approval of post-transition changes.

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5. The joint probability floor value recommended in NUREG-1792 was not used in the Fire PRA. The TVA response to PRA RAI 01.v (in this enclosure) states that in subsequent Fire PRA quantifications, a joint probability floor of 1E-5 will be used for all combinations that do not include long term DHR HFEs. For combinations that include long term DHR HFEs, a joint probability floor of 1E-6 will be used. The TVA response to PRA RAI 01.v provides the results of a sensitivity analysisThe quantitative screening criteria has been updated to be consistent with the criteria in NUREG/CR-6850 Task 7 and non-propagating fire scenarios that do not screen are included in the composite analysis provided in response to PRA RAI 24, Part a (in Enclosure 1 of this letter) and the PRA that will be used at the beginning of the self-approval of post-transition changes.

TVA previously identified the following deviations which were not included in LAR, Attachment V. LAR Attachment V has been updated (as shown in Enclosure 6 of this letter) to include discussion of the following items.

16.The MCR analysis indicates that frequency is apportioned by tray length and not weight or combustible loading as suggested by NUREG/CR-6850. TVA uses a different approach for apportionment of cable tray fire frequencies than is suggested in PRA FAQ 13-0005, the cable fire scenarios analyzed in the BFN MCR analysis conservatively assesses the risk represented by cable fire scenarios in the MCR.

The revised TVA response to PRA RAI 17.d (in TVA letter dated February 13, 2014this enclosure) provides the basis for the approach used in the analysis.

The first five above described deviations will be included in the quantification in the next revision of the baseline Fire PRA model. After these changes in methods are implemented, the affected sections in the LAR will be revised to reflect the results of the updated Fire PRA quantifications. The revision to the LAR will be provided to the NRC after the Fire PRA is updated and additional quantification is performed in response to remaining NRC RAIs.

2. The apparent deviation noted for F&O 2-56 was addressed in the TVA response to PRA RAI 01.h, Part i (in TVA letter dated February 13, 2014), that provided the basis for the approach used in the analysis.

TVA used parts of the guidance described in the June 21, 2012, memo from NRC to NEI, "Recent Fire PRA Methods review Panel Decisions and EPRI 1022993, 'Evaluation of Peak Heat Release Rates in Electrical Cabinets Fires,' " (hereinafter referred to as "the June 21 memo") as discussed below.

1. For "Frequencies for Cable Fires Initiated by Welding and Cutting," TVA incorporated the June 21 memo guidance for updated frequencies for cable fires initiated by welding and cutting, with no deviations. Therefore, a sensitivity study is not required.

2. Clarification for Transient Fires: For most fire compartments, TVA analyzed transient fires consistent with the guidance in NUREG/CR-6850, with no deviations. TVA applied the June 21 memo guidance to reduce the transient heat release rates in other fire compartments. This is discussed in LAR Section V.2.3 and the TVA response to PRA RAI 16 (in TVA letter dated February 13, 2014). Because TVA did not deviate from either of these NRC endorsed methods, a sensitivity study is not required.

3. Alignment Factor for Pump Oil Fires: With the exception of oil fire scenarios for Control Bay Chillers 3A and 3B in the CSR, TVA analyzed oil fires consistent with the guidance E3-61

in NUREG/CR-6850, with no deviations. As described in the revised TVAs response to FM RAI 01.g (in TVA letter dated January 14, 2014this enclosure) addressing oil fire scenarios for Control Bay Chillers 3A and 3B in the CSR included a sensitivity study using the oil alignment factors from the June 21 memo. Because TVA did not deviate from either of these NRC endorsed methods, a sensitivity study is not requiredthe treatment of the 100% oil fires was not changed; however, a change was noted with the treatment of the 10% oil fires. This revision of the oil fire scenarios for Control Bay Chillers 3A and 3B in the CSR is consistent with the treatment of oil fire scenarios in NURER/CR-6850 and is no longer considered a deviation. These fire modeling updates to the control bay chiller oil spill fire scenarios have been reflected in the updated fire risk results provided in the TVA response to PRA RAI 24, Part a (in Enclosure 1 of this letter).

4. Electrical Cabinet Fire Treatment Refinement Details: This guidance is not endorsed by the NRC and was not used by TVA.

5. EPRI 1022993, "Evaluation of Peak Heat Release Rates (HRRs) in Electrical Cabinet Fires": This guidance is not endorsed by the NRC and was not used by TVA.

TVA has identified no other deviations from accepted methods and approaches.

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PRA RAI 10 TVA previously responded to PRA RAI 10 by letter dated March 14, 2014 (CNL-14-025). LAR Attachment S, Table S-2, Modifications 78 and 79 had proposed modifications to install an area wide incipient (i.e., very early warning) fire detection system, that uses very early warning fire detectors (VEWFDs), and a new automatic gaseous fire suppression system, in the CSRs, respectively. As discussed in the revised TVA responses to FPE RAI 10 and FPE RAI 11 in this enclosure, TVA has decided not to install the area wide very early warning fire detection system and the automatic gaseous suppression system in the CSRs.

The below revised response supersedes the previous response for PRA RAI 10 in its entirety.

The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE As discussed in the revised TVA response to FPE RAI 10 in this enclosure, TVA has determined that the proposed modifications described in LAR Attachment S, Table S-2, Modification 77 and Modification 78 to install area wide incipient (i.e. very early warning) detection systems, using very early warning fire detectors (VEWFDs), in the auxiliary instrument rooms (i.e., Fire Compartments 16-K, 16-M, and 16-O) and CSRs, respectively, and discussed in LAR Attachment V will not be installed. In addition, as discussed in the revised response to FPE RAI 11 in this enclosure, TVA has determined that the proposed modification described in LAR Attachment S, Table S-2, Modifications 78 and 79 propose modifications to install an area wide very early warning detection system and a new automatic gaseous fire suppression system in the cable spreading rooms (CSRs) and discussed in LAR Attachment V will not be installed. Therefore, the remainder of this response addresses only the area wide systems in the CSR portion of Fire Compartment 16-A.

Part a As discussed in LAR Attachment V,Section V.2.4, the Fire PRA credits both prompt detection and automatic suppression for transient fires, cable fires caused by welding and cutting, transient fires caused by welding and cutting, and self-ignited cable fires. This credit is based on the VEWFDs (i.e., aspirating smoke detectors) to be installed as part of the very early warning fire detection system in the CSRs.

Current plans include VEWFDs to send pre-activation alerts to plant personnel, as discussed in the TVA response to FPE RAI 12, Part d. The detectors are not credited to detect the fire in its incipient phase. Instead, prompt detection and suppression is credited for preventing fire propagation beyond the fire origin only, which is within the guidance in NUREG/CR-6850, Appendix P for a high-sensitivity smoke detection system.

Transient fires and self-ignited cable fires credited prompt detection, via the very early warning fire detection system, to actuate the automatic suppression system, which limited the target damage to one cable tray. When either prompt detection or automatic suppression was unsuccessful, all targets in the CSR were considered damaged.

Transient fires caused by welding and cutting and cable fires caused by welding and cutting credited prompt detection, via the very early warning fire detection system, to actuate the automatic suppression system and limit the fire damage to one cable tray. If the detection system was unsuccessful, the fire watch was credited to promptly detect the fire and manually suppress it, which also limited the target damage to one cable tray. If the detection system, E3-63

automatic suppression system, or fire watch was unsuccessful, all targets in the CSR were assumed to be damaged.

Part b As discussed in the TVA response to FPE RAI 12, Part d, the CSR area wide detection system and the associated suppression system will be designed, installed, operated, and maintained to the specifications in NFPA 72, NFPA 76 for response transport times and sensitivity settings, NFPA 2001, "Standard on Clean Agents Fire Extinguishing Systems," and manufacturer listing requirements. Both systems will provide area wide coverage for the CSR. The system designs will incorporate adequate concentrations and the detectors and nozzles for the systems will be located such that a fire in any location of the CSR can be properly detected and/or extinguished by these systems.

The existing guidance in NUREG/CR-6850, Appendix P, recommends the treatment of high-sensitivity smoke detectors by crediting a prompt detection response. TVA recognizes that a very early warning fire detection system in an area wide application introduces an additional layer of complexity, in that the specific location of the fire may not be immediately apparent.

That being the case, it may not be until the fire has grown beyond the incipient phase (i.e., until it has entered the active burning/growth phase) that its location becomes apparent. Given this consideration, no credit is assumed in the Fire PRA for suppression to prevent damage to the source of the fire. Instead, prompt detection and suppression are credited for preventing fire propagation beyond the fire origin only.

Therefore, the area wide detection system and the associated suppression system will be able to effectively control the postulated fires in Fire Compartment 16-A, consistent with the guidance provided in NUREG/CR-6850, Sections 11.5.1.8.2 and P.1.2.

Part c The availability and reliability of the CSR area wide detection system is justified and explained in detail in the TVA response to FPE RAI 12, Part a.

A total flooding clean agent suppression system will be installed in the CSR portion of Fire Compartment 16-A. Applying an unavailability and unreliability value of 2E-02 for the area wide total flooding suppression system was appropriately included in the Fire PRA, based on the following:

The new total-flooding, clean agent system will be designed, installed, and maintained to the current NFPA standard (NFPA 2001) for Clean Agent Fire Extinguishing Systems.

NUREG/CR-6850 uses the failure probabilities (i.e., system reliability) for automatic suppression systems based on NSAC-179L, "Automatic and Manual Suppression Reliability Data for Nuclear Power Plant Fire Risk Analyses," April 1994. NSAC-179L examined fire events up to 1988 that are now over 26 years old. Many of these systems were likely installed more than 26 years ago. A new system will be designed and installed incorporating decades of technological improvements and code/standard refinement to significantly improve system reliability, for example:

x Later editions of NFPA 2001 contain more definitive requirements, calculation methods and guidelines for establishing minimum design concentrations, safety factors, agent quantity, hold times, etc., for all types of fires, including deep-seated fires. Additional design factors include: unclosable openings, acid gas formation, fuel geometry, E3-64

enclosure geometry, obstructions, uncertainty of agent quantity distribution at tee splits, and agent lost through initial compartment relief venting.

x Enhanced electronic supervision capabilities for all system components and features necessary for proper system operation. Current industry standard practice includes audible and visual indication of all adverse conditions (e.g., low cylinder pressure, wiring/circuit faults, damper status/closure, actuating devices, power interruption).

The fire scenarios crediting the total flooding suppression system in the Fire PRA account for the unreliability and unavailability of the detection system with a value of 1E-02, as discussed in the TVA response to FPE RAI 11, Part b, independently. This is conservative when compared to the non-suppression probability values in NUREG-6850, Appendix P, for gaseous suppression systems, which include detection failures.

In addition, the sensitivity analysis discussed in LAR Section V.2.4 analyzed the effect of changing the total probability of non-suppression to 5E-02. Selecting a non-suppression probability of 5E-02 bounds the reliability of Halon, deluge and pre-action systems, which have the lowest reliability of the recommended values in NUREG/CR-6850, Appendix P. As a result of this sensitivity, BFN meets the guidance for a Region II plant with total CDF and LERF below 1E-04/rx-yr and 1E-05/rx-yr, respectively, for overall plant risk. BFN also meets the CDF/LERF criteria for a Region II plant which allows a positive ¨CDF of 1E-05/rx-yr and ¨LERF of 1E-06/rx-yr for acceptable risk increases.

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PRA RAI 10.c.01 TVA previously responded to PRA RAI 10.c.01 by letter dated October 6, 2014 (CNL-14-172).

LAR Attachment S, Table S-2, Modifications 78 and 79 had proposed modifications to install an area wide incipient (i.e., very early warning) fire detection system, that uses very early warning fire detectors (VEWFDs), and a new automatic gaseous fire suppression system, in the CSRs, respectively. As discussed in the revised TVA responses to FPE RAI 10 and FPE RAI 11 in this enclosure, TVA has decided not to install the area wide very early warning fire detection system and the automatic gaseous suppression system in the CSRs.

The below revised response supersedes the previous response for PRA RAI 10.c.01 in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE As discussed in the revised TVA responses to FPE RAI 10 and FPE RAI 11 in this enclosure, TVA has determined that the proposed modifications described in Attachment S, Table S-2, Modification 78 to install area wide incipient (i.e., very early warning) detection systems using very early warning fire detectors (VEWFDS), and Modification 79 to install a new automatic gaseous suppression system in the CSRs will not be installed.

The unavailability and unreliability value of 2.0E-02 applied for the non-detection portion of the proposed clean agent system is based on the United Facilities Criteria (UFC) 3-601-02.

UFC 3-601-02 provides an Inspection, Testing, and Maintenance (IT&M) program for achieving 99% system performance. UFC 3-601-02 references U.S. Air Force: Headquarters Air Force Civil Engineer Support Agency Operations and Programs Support Division (AFCESA/CES)

Technical Report 01-10, which provides a system availability and reliability of 0.99 for total-flooding clean agent systems. This 0.99 value includes the detection capability of the system.

The IT&M program provided in UFC 3-601-02 is consistent with NFPA and manufacturer requirements and frequencies. Therefore, a total-flooding clean agent system, including the detection system components, when designed and installed per NFPA 2001, Standard for Clean Agent Fire Extinguishing Systems (2012) and maintained in accordance with NFPA and manufacturer requirements is capable of achieving a 0.99 availability and reliability value. For the Fire PRA, TVA used the value of 2.0E-02 for the suppression system components and a value of 1.0E-02 for the detection system components. These values combined provide a conservative value exceeding the value found in the UFC 3-601-02.

An additional representative data point provided in NSAC-179L, Automatic and Manual Fire Suppression Reliability Data for Nuclear Power Plant Fire Risk Analyses, for Halon systems shows a value of 1.6E-02, when not including the detection systems.

In summary, the availability and reliability value of 2.0E-02 represents the non-detection components of the clean agent suppression system, and is conservative with respect to current performance criteria from the UFC. The value also reflects that the new gaseous suppression system and components will be listed/approved by a nationally recognized testing agency, installed in accordance with manufacturer requirements and current codes and standards (which have undergone significant changes over the past 26 years), and will be fully supervised and monitored.

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TVA is considering the deletion of one or both of the modifications related to area wide Incipient Detection and automatic gaseous fire suppression in the Cable Spreading Rooms (i.e., LAR, Table S-2, "Plant Modifications Committed," items 78 and 79) as discussed in TVA Letter dated September 16, 2014. The final disposition of these modifications will be reflected in the submittal of updated fire risk results planned for December 17, 2014.

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PRA RAI 11, Part a TVA previously responded to PRA RAI 11, Part a, by letter dated January 14, 2014 (CNL-14-006). TVA has modified the event tree to credit alternate shutdown cooling and the Emergency High Pressure Makeup (EHPM) pump cooling capability for the fire model. of this letter provides the non security-related markup of the change to LAR Table S-3, Implementation Item 47i.

The below revised response supersedes the previous response for PRA RAI 11, Part a in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE In general, the Fire PRA model followed the guidelines of NUREG/CR-6850 and the High Level Requirements (HLRs) and Supporting Requirements (SRs) of ASME/ANS RA-Sa-2009. Listed below are the HLRs and SRs that were deemed not applicable (N/A) to the Fire PRA model by the full scope peer review team and the justifications for classifying them as such.

1) The Fire PRA model was adapted from the internal events model using the same inputs and parameters, except for modifications to represent fire risk events. In the development of the Fire PRA model, the requirements of the following HLRs and SRs were not affected. They were evaluated during the internal events peer review and met Category II or better. Some SRs had associated F&Os which were resolved as specified in LAR Attachment U.

DA-A IE-C11 QU-C3 SY-A20 DA-B IE-C14 SC-A1 SY-B3 DA-C LE-A SY-A9 SY-B4 DA-E LE-B SY-A11 IE-C6 LE-C SY-A15 IE-C10 LE-D SY-A16

2) SR SY-A19 was identified in LAR Table V-1 as "not applicable" but should be marked as "Met." SY-A19 was determined to be not applicable at the time of the peer review because the BFN Fire PRA model used the internal events PRA model information for unavailability of components. The new components added for the Fire PRA, except for the EHPM pump, were modeled for unavailability caused by damaging fires only, because the out-of-service unavailability of the new components is included in the component or function it supports. Because the EHPM pump was added to the Fire PRA model for both unavailability due to test or maintenance, as well as a damaging fire causing unavailability, the SR was met for Capability Category I, II, and III. Therefore, this SR should be identified as "Met." LAR Attachment V, Table V-1, which provides the list of High Level Requirements (HLRs) and SRs that are not applicable, is revised to remove SY-A19 (in the fourth column of the Table) from Table V-1.

3) Two new initiating events (IEs) were identified in the Fire PRA review as being applicable to the Fire PRA: General Transient (GTRAN) and Stuck Open Relief Valve (IOOV). However,Both of these IEs were already accounted for in the existing event tree/accident sequences. The event trees were modified to show credit for Alternate Shutdown Cooling (ASDC) and credit for the EHPM pump for the GTRAN and IOOV event trees. These trees were modified to credit alternate shutdown cooling and injection from the high pressure makeup pump for fire events only.

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These sources of cooling are not being credited in the internal events model. No new event trees/accident sequences were implemented in the Fire PRA. See the disposition to PRM-B3 on pages V-73 and V-74 of the BFN NFPA 805 LAR for a detailed description of the modeling of fire induced initiating events. Therefore, the following HLRs/SRs were identified as not applicableThese updates may affect the following SRs but will be assessed during the upcoming focused scope peer review:

AS-A2 AS-A9 AS-B7 IE-A6 AS-A3 AS-A11 AS-C IE-A7 AS-A4 AS-B1 IE-A1 IE-A9 AS-A6 AS-B2 IE-A2 IE-A10 AS-A7 AS-B5 IE-A3 IE-B AS-A8 AS-B6 IE-A5 PRM-B6

4) There were notwo new success criteria modeled in the Fire PRA that have been identified that require plant response model construction. The definition of success criteria, as specified in ASME/ANS RA-Sa-2009, is the minimum number or combinations of systems or components required to operate to ensure safety functions are satisfied. The Aadditional components (i.e., ASDC and EHPM pump) were included in the Fire PRA model to support the new top events. These modes of cooling were only credited for the fire model and were not credited for the internal events model. These updates may affect the following SRs but will be assessed during the upcoming focused scope peer reviewdid not affect the minimum number or combinations of systems or components required to operate. They were added to provide another level of redundancy, and as such, the following Supporting Requirements were deemed not applicable:

PRM-B8 SC-A3 SC-B2 SC-A2 SC-A4 SC-C2

5) PRM-B15 was deemed not applicable because there was no new Fire PRA specific accident progression identified beyond the onset of core damage which addresses LERF estimation in the internal events PRA.

6) The Fire PRA HRA initially used the same human actions as the internal events model.

These human actions were further refined in accordance with the Supporting Requirements for HRA-A, HRA-B, HRA-C, and HRA-D. Because all the requirements in the HR HLRs were included in the HRA HLRs, the following HLRs/SRs were deemed not applicable:

HR-A HR-C HR-H1 HR-B HR-D

7) SRs IE-C15 and IE-D were previously covered by the IGN and CF SRs while SRs under MU-A, MU-B, MU-C, MU-D, and MU-E were covered under the FMU SRs.

8) The cable selection process does not include any assumed routing cases. The Fire PRA team identified a set of components for which the location of associated cables was identified. All other components were assumed to fail for all fire scenarios; therefore CS-A11, CS-C3 and FSS-E4 were deemed not applicable.

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9) SR FQ-F2 requires documentation to support any claim of nonapplicability of referenced requirements in Section 2 of ASME/ANS RA-Sa-2009 standard. The Fire PRA analysis did not claim nonapplicability of any of those requirements, and as such, FQ-F2 was deemed not applicable.

10) SR IE-C7 requires a time trend analysis to meet Capability Category III, but no time trend analysis is required for Capability Category II. The BFN PRA did not include a time trend analysis, and as such, IE-C7 was deemed not applicable.

11) Internal flooding does not affect the Fire PRA; therefore the following HLRs/SRs were deemed not applicable.

IFEV-A IFPP-B IFSN-A IFSO-A IFEV-B IFQU-A IFSN-B IFSO-B IFPP-A IFQU-B

12) SR ES-B5 provides relief for components susceptible to fire-induced spurious operations. The provisions of this SR have not been used in the Fire PRA, therefore it was deemed not applicable.

13) Based on the plant-specific review of BFN fire events from January 1, 2000 to December 31, 2009, for Units 1, 2 and 3, a total of 67 fire events were identified and reviewed, with 59 of these events being immediately screened from further consideration based on where and when the fire events occurred. The eight remaining events were placed into their respective fire ignition bins. Only one of these events was identified as potentially challenging, due to fire in a cabinet located in a flammable environment.

No unusual patterns of occurrence or outlier fire events were noted. Given that there were no unusual patterns of fires and no more than one fire event per bin that was not immediately screened based on where and when the fire event occurred, no plant specific updates of generic frequencies were considered. Guidance in NUREG/CR-6850, Section 6.5.2 states that if there are only a small number of fire events in the plant, use of generic fire frequencies is warranted. With only one plant specific fire event associated with each bin, the frequency of that bin would increase significantly if Bayesian updates were employed. Typically the fire frequency for each bin was smaller than once per 100 years, while a plant will have less than 100 years of total experience.

Therefore, with just one fire event the frequency would increase significantly after performing a Bayesian update. The updated frequency would be overly conservative based on a small probability that the event occurs early in the observation period.

Because generic industry parameters were used in the BFN analysis, the following SRs were deemed not applicable:

DA-D IE-C2 IE-C4 IE-C13 FSS-E2 IE-C3 IE-C12 IGN-A6

14) No parameters outside the bounds of HLR-FSS-C or HLR-FSS-D have been credited in the Fire PRA, therefore, FSS-E1 was deemed not applicable.

15) The Alarm Response procedures, the EOIs, and the abnormal operating instructions (AOIs) were all reviewed to determine whether there were any spurious alarms or indications that could cause an undesired operator action that could cause a detrimental effect in the Fire PRA. All of the alarms required verification, either by using indications E3-70

from other parameters, or by manual verification. The AOIs were reviewed and were determined that upon entry into the procedure multiple indications and conditions are required to be verified as a part of the procedure. Almost all of the steps in the EOIs have multiple sources and channels in the MCR. Other steps have multiple means of detection from the MCR. All other spurious indications from a single instrument that could cause an undesired operator action were assumed to be failed in the Fire PRA.

Therefore, HRA-B4 was deemed not applicable.

16) During development of the Fire PRA, the plan was to screen compartments using guidance from NUREG/CR-6850 and the ANS/ASME PRA Standard. Although several compartments fell below the criteria specified in NUREG/CR-6850 and the ANS/ASME PRA Standard, no compartments were screened out of the analysis. All compartments were retained for further analysis and therefore, the following HLRs/SRs were deemed not applicable:

QLS-A QNS-A* QNS-C QLS-B QNS-B* QNS-D*

Note: Except for QNS-D2, these HLRs were originally marked as "Met" because a screening analysis was performed. Although several compartments fell below the criteria laid out in NUREG/CR-6850 and the ANS/ASME PRA Standard, no compartments were screened out in the analysis. All compartments were retained for further analysis so each of these HLRs and SRs included therein were judged to be not applicable as well. LAR Attachment V, Table V-1 is revised to add QNS-A, QNS-B and QNS-D to the Table and delete QNS-D2 (in the fifth column of the Table) from the Table.

17) There are no subtrees, modules or split fractions used in the Fire PRA model, therefore AS-B4 and QU-B10 were deemed not applicable:

18) The Fire PRA is a spatial analysis so any comparison would require the identification of a plant with a similar arrangement of cables, raceways, and ignition sources. No such plant exists; therefore, QU-D4 was deemed not applicable.

19) The Fire PRA model does not use non-nuclear power industry sources for fire ignition frequencies; therefore, SRs IGN-A2 and IGN-A3 were deemed not applicable.

20) With regard to SR FSS-C7, there were no dependencies between automatic suppression and manual suppression. If automatic suppression failed, the fire PRA did not take credit for fire brigade manual initiation of the failed automatic suppression system. The only dependency was between automatic detection and manual suppression. If automatic suppression was successful, there was no need for manual suppression. If automatic suppression failed, and automatic detection was successful, Operations personnel would dispatch the fire brigade to manually suppress the fire. If automatic detection failed, manual detection would prompt action from the fire brigade to manually suppress the fire. The dependency between Fire PRA modeling of automatic and manual detection and suppression is further discussed in the TVA response to PRA RAI 01 Part j in this enclosure. Therefore, this SR was deemed not applicable.

21) SR AS-A10, this was previously marked as "not applicable" but should be marked as a "Not Met" finding. This SR is similar to AS-A1 and AS-A5, in regard to the fire emergency response procedures. The Fire PRA model followed the internal events model. The Fire PRA model took credit for draft fire emergency response procedures that provided descriptions of operator actions dealing with fires. The Fire PRA team E3-71

worked closely with the overall NFPA 805 transition team to develop the draft fire emergency response procedures. While no significant changes are expected to be made to the draft procedures, any change made during the development of the final procedures will be appropriately incorporated into the model and will be reviewed for adequacy consistent with the commitment specified in LAR Attachment S, Table S-3, Implementation Item 33. This will also be discussed in the TVA response to PRA RAI 01 Part d (in a future letter). In addition, LAR Attachment V, Table V-1 is revised to delete AS-A10 (in the first column of the Table) from the Table.

As described in the TVA response to PRA RAI 24.b (in the TVA letter dated October 6, 2014), a focused scope peer review will be performed prior to transition to NFPA 805. To ensure this peer review is performed, the TVA response to PRA RAI 11.b and 11.c added Implementation Item 47, to LAR Table S-3. The LAR requires that certain items be completed prior to the implementation of the NFPA 805 fire protection program.

The response to PRA RAI 23.d (in the TVA letter dated March 14, 2014), as corrected in of TVA letter dated October 6, 2014, further revised the proposed Implementation Item 47 provided in the response to PRA RAI 11.b and c to include the LERF Analysis (element LE-C6) and the response to PRA RAI 24.b added a statement to provide assurance that the focused scope peer review findings will be resolved before self-approval of post transition changes as follows: "Perform a focused-scope peer review of the Fire PRA. The peer review will include, as a minimum, the following elements: Fire PRA Cable Selection and Location (CS), Human Reliability Analysis (HRA),

Fire Risk Quantification (FQ), Uncertainty and Sensitivity Analysis (UNC), and LERF Analysis (element LE-C6). Any focused scope peer review Finding level Facts &

Observations (F&Os) will be resolved prior to self-approval of post-transition changes."

In addition to reviewing the above Fire PRA elements, the peer review will also include a review of the Accident Sequence Analysis (AS). This response to PRA RAI 11.a revises the proposed LAR, Table S-3 Implementation Item 47 as follows: "Perform a focused-scope peer review of the Fire PRA. The peer review will include, as a minimum, the following elements: Fire PRA Cable Selection and Location (CS), Human Reliability Analysis (HRA), Fire Risk Quantification (FQ), Uncertainty and Sensitivity Analysis (UNC),

Accident Sequence Analysis (AS) and LERF Analysis (element LE-C6). Any focused scope peer review Finding level Facts & Observations (F&Os) will be resolved prior to self-approval of post-transition changes."

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PRA RAI 17, Part d TVA previously responded to PRA RAI 17, Part d, by letter dated February 13, 2014 (CNL-14-020). TVA has revised the response to clarify that the Fire Compartment frequency is based on combustible loading. Only the scenario level goes to cable length. In addition, TVA has revised the response to delete specific level of detail related to percentages of cable fire frequency. Refinements made to offset risk increases elsewhere have changed the percentage values reported in the original response. Rather than update these values and continue to maintain this very specific level of detail, TVA has revised the response to a more of general discussion of technical approach. Also, to address concerns of being overly "conservative" and overestimating risk, TVA has added additional information to explain that although conservative, the Main Control Room (MCR) cable fire scenarios are appropriate and meet risk objectives.

The below revised response supersedes the previous response for PRA RAI 17, Part d in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE The two types of cable fire scenarios considered in the MCRs were Bin 5, cable fires caused by welding and cutting (i.e., Bin 5 scenarios) and Bin 12, self-ignited cable fires (i.e., Bin 12 scenarios). Fire Compartment 16-A consists of the MCRs and the CSRs.

The plant-wide cable fire scenario frequencies are apportioned to Fire Compartment 16-A by combustible loading. The frequencies are further subdivided between the MCR and the CSR by the combustible loading ratio between the two areas. This is consistent with the cable combustible loading weighting approach recommended in NUREG/CR-6850.

With the cable tray fire frequency apportioned by tray length, the MCRs are 6.69% of the cable fire frequency for Fire Compartment 16-A. Using the cable weighting, or combustible loading, approach suggested by NUREG/CR-6850, the cable fire frequency for the MCRs are 10.1% of the total cable fire frequency of Fire Compartment 16-A.

Within the MCR, the resultant room cable fire scenario frequency was further subdivided into fire scenarios. These scenarios were assigned a frequency based on the ratio of tray length for each fire scenario. TVA acknowledges that the resulting fire ignition frequency for cable fires in the MCRs using the guidance of NUREG/CR-6850 is higher than the method TVA utilizedusing tray length for cable fires scenarios in the MCR does not necessarily agree with the guidance of NUREG/CR-6850. However, in the BFN analysis, the cable fire scenarios were divided up by unit and conservatively assumed damage to all cable trays located in that units MCR. The current guidance in the NRC-approved Fire PRA FAQ 13-0005 limits damage from cable fires to the raceway of origin, not all the cable trays located in the MCRs, as was assumed in the BFN analysis. Therefore, using the methodology of failing all cables in each unit to analyze the cable fire scenarios in the MCRs is conservative and more than offsets any potential non-conservatism in the ignition frequency apportionment.

Based on historical data of cable fires in U.S. nuclear power plants, a more realistic methodology has been approved by Fire PRA FAQ 13-0005 for self-ignited and hot work-initiated cable fires. Using the methodology in Fire PRA FAQ 13-0005 significantly reduces the risk impact from cable fire scenarios. In addition, all cable trays were conservatively assumed to result in self-ignited cable fires, without analyzing the specific cables contained in each cable tray. Based on industry guidance, some trays do not have the potential to create self-ignited cable tray fires. For instance, self-ignited non-power cable fire scenarios do not need to be considered because of an extremely low probability of occurrence and many cable trays in the E3-73

MCRs do not contain power cables. Also, based on NUREG/CR-6850, Appendix R, self-ignited cable fires should be postulated in cable trays with unqualified cables only or a mix of qualified and unqualified cables. It is likely that some cable trays within the MCRs do not contain unqualified cables and therefore self-ignited cable fires would not need to be postulated for these trays.

Consistent with Fire PRA FAQ 13-0005, based on risk contribution, the self-ignited cable fire scenarios have been refined by an iterative process to reduce the risk contribution of these scenarios until the risk is low enough to meet the PRA objective. The criteria for determining whether a fire scenario would be evaluated for further refinement is based on meeting the Fire PRA objective of refining scenarios to a CDF/LERF of less than or near 1E-07/yr, 1E-08/yr, respectively.

In conclusion, even though TVA uses a different approach for apportionment of cable tray fire frequency than is suggested in NUREG/CR-6850, the cable fire scenarios analyzed in the MCR analysis conservatively quantify the risk represented by cable fire scenarios in the MCRs and meet the risk objectives.

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PRA RAI 17, Part e TVA previously responded to PRA RAI 17, Part e, by letter dated February 13, 2014 (CNL-14-020). The TVA response to PRA RAI 17, Part e is revised to reflect that the final MCR abandonment criteria are stated in the TVA response to PRA RAI 04.01 (in TVA letter dated October 6, 2014).

The below revised response supersedes the previous response for PRA RAI 17, Part e in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE Multi-unit effects were addressed in the MCR modeling as follows:

x Main Control Room Fire Scenarios - Each MCR scenario was quantified for each unit in the Fire PRA model. This ensures that no risk significant scenarios are omitted. A number of the control board scenarios have shared features such as the Unit 0 control board located in the Units 1 and 2 MCR. These MCB scenarios contain targets that affect controls for multiple units.

x Habitability Abandonment - The Units 1 and 2 control rooms make up one large room, whereas Unit 3 has its own control room. The control room abandonment times were calculated for the combined MCR for Units 1 and 2, which has a larger volume leading to longer abandonment times than Unit 3.

x Functionality Abandonment - Functionality abandonment multi-unit impacts are described in the TVA response to PRA RAI 04.01 (in TVA letter dated October 6, 2014)Functionality abandonment occurs when the fire damage alone in a scenario leaves no available safe shutdown success path for the affected unit. These scenarios assumed that operators would abandon the control room and use ex-control room alternative shutdown procedures. In order to identify those scenarios which result in this level of equipment damage, each scenario in the affected fire compartments for each unit was evaluated without crediting the EHPM pump modification; if the resulting cutsets based on review showed no safe shutdown path was available then the use of alternative shutdown would be required.

x Shared Systems - There are a number of shared systems at BFN, such as plant air, raw cooling water, RHR, Service Water (SW), Emergency Equipment Cooling Water (EECW), and electrical power. These shared systems are directly modeled in the Fire PRA Computer Aided Fault Tree Analysis (CAFTA) to invoke multi-unit initiators and system failures. These events generally involve degradation or loss of support systems that are common to each unit. Therefore, the system-by-system analysis for plant-specific failures includes consideration of the effects of system degradation on the other units.

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PRA RAI 18, Part b TVA previously responded to PRA RAI 18, Part b, by letter dated January 10, 2014 (CNL-14-001). The TVA response to PRA RAI 18, Part b is revised to reflect that Alternate Shutdown Cooling (ASDC) is now modeled in the Fire PRA.

The below revised response supersedes the previous response for PRA RAI 18, Part b in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE Part b.

The approach described in LAR Attachment W, Section W.2.1 was used for all Variance from Deterministic Requirements (VFDRs) where the Fire PRA modeled the NSCA equipment associated with the VFDR. An extension of the process was used for cases where the Fire PRA did not model the exact equipment associated in the VFDR as identified in the NSCA. For example, the PRA did not model the logic associated with the Alternate Shutdown Cooling mode of RHR. This mode was credited in the NSCA as a means of Decay Heat Removal (DHR). To model the CDF and LERF associated with these components' Alternate Shutdown Cooling VFDRs, the compliant plant model was reviewed and basic events associated with an equivalent higher level function (i.e., suppression pool cooling as a means of DHR) were "toggled off." The generic approach was to ensure the compliant model restored the higher level function associated with failure of the VFDR. Another example of this approach included process monitoring VFDRs, in which the Fire PRA credited different instrumentation than the specific VFDR. The basic events associated with failure of the function supported by the instrumentation were reviewed and the basic events "toggled off" for the equivalent function, as required. For systems not required to be modeled in the Fire PRA such as electric board room HVAC, there was no CDF or LERF associated with the VFDR because the equipment did not contribute to the risk of compliant plant. Thus there was no toggling of basic events or recovery actions for these cases.

The specific case of the modeling of MCR abandonment scenarios and calculation of CDF and LERF were treated as described in LAR Attachment W, Section W.2.1; by modeling success of recovery actions or by modeling the actions being performed at the primary control station. A description of the modeling and treatment of abandonment scenarios is provided in the response to PRA RAI 18, Part a.

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PRA RAI 19, Part a TVA previously responded to PRA RAI 19, Part a, by letter dated January 10, 2014 (CNL-14-001). TVA has revised the response to PRA RAI 19, Part a to reflect that quantitative results demonstrating that the magnitude of the risk reduction from the improvements being implemented to reduce risk is greater than the magnitude of the risk of the retained VFDRs is provided in the TVA response to PRA RAI 19.b.01, Part c in Enclosure 1 of this letter.

The below revised response supersedes the previous response for PRA RAI 19, Part a in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE Part a.

The total change in CDF and LERF is provided in LAR are, Section W.2.2, as a sum of the risk increases and decreases. The total risk increase and decrease at the Fire Area level for BFN Units 1, 2, and 3 are provided below:

Total Total Unit +CDF1 -CDF1 +LERF1 -LERF1 CDF1 LERF1 Unit 1 1.89E-06 -5.39E-04 2.70E-07 -7.74E-08 -5.37E-04 1.93E-07 Unit 2 9.92E-07 -4.67E-04 1.46E-07 -1.14E-07 -4.67E-04 3.19E-08 Unit 3 0.00E+00 -5.45E-04 1.58E-07 -3.92E-08 -5.45E-04 1.18E-07 Note 1: In some cases, the summation of the positive and negative CDF and LERF results in slightly different total CDF and LERF than reported in the LAR. The differences are minor and are the result of rounding. The LAR totals are shown in the Total CDF and Total LERF columns in this table.The quantitative results (i.e., core damage frequency (CDF), large early release frequency (LERF), change in (¨) CDF, and ¨LERF values) of an assessment that demonstrates that the magnitude of the risk reduction from the improvements being implemented to reduce risk is greater than the magnitude of the risk of the retained VFDRs is provided in the TVA response to PRA RAI 19.b.01, Part c in Enclosure 1 of this letter.

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PRA RAI 19, Part b TVA previously responded to PRA RAI 19, part b, in a letter dated January 10, 2014 (CNL 14-001). TVA provided an update to PRA RAI 19, Part b in a letter dated February 13, 2014 (CNL-14-020) that corrected an error in some of the values in the table providing the risk significant fire scenarios in Fire Area (FA) 08 for the Unit 1, 2 and 3 compliant Fire PRA models. The TVA response to PRA RAI 19, Part b, as revised by TVA letter dated February 13, 2014, is revised to reflect the changes to the top scenarios in the compliant plant resulting from the updated Fire PRA model.

The change from the previous updated response, dated February 13, 2014, is shown with deleted text struck through, inserted text in bold, underline, and a revision bar to the right.

REVISED RESPONSE Part b.

Summarized below are the top few risk significant scenarios for risk significant fire areas in the compliant case. In each scenario in the compliant case, basic events associated with VFDRs on the credited train in NSCA have been removed from being failed by the fire. The core damage and large early release scenarios described here are the results of:

x Fire-induced failures (with the exception of those associated with the credited train).

x Random failures of the credited train.

The following discussion of the risk significant scenarios in FA 16 applies to BFN Units 1, 2, and 3 compliant Fire PRA model:

CCDP1 IGF (Conditional CDF1 (Core (Ignition Core Damage Damage Unit Scenario Frequency) Probability) Frequency)

Unit 1 16-K.023-CAB-SUP 8.31E-05 9.64E-02 8.00E-06 Unit 1 16-K.024-CAB-SUP 8.31E-05 9.64E-02 8.00E-06 Unit 2 16-M.022-CAB-SUP 8.31E-05 9.64E-02 8.00E-06 Unit 2 16-M.023-CAB-SUP 8.31E-05 9.64E-02 8.00E-06 Unit 3 16-O.025-CAB-SUP 8.31E-05 9.64E-02 8.00E-06 Unit 3 16-O.024-CAB-SUP 8.31E-05 9.64E-02 8.00E-06 Unit 1 Main Control Room 6.00E-05 4.90E-01 2.94E-05 Habitability Abandonment Unit 1 16-A.3505-TWC-ALL-CSR 4.91E-06 4.89E-01 2.40E-06 Unit 2 Main Control Room 6.00E-05 4.55E-01 2.73E-05 Habitability Abandonment Unit 2 16-A.3505-TWC-ALL-CSR 4.91E-06 4.55E-01 2.24E-06 Unit 3 Main Control Room 6.00E-05 4.61E-01 2.77E-05 Habitability Abandonment Unit 3 16-A.3505-TWC-ALL-CSR 4.91E-06 4.61E-01 2.27E-06 E3-78

Note 1: The CCDP is an average value based on the total CDF and the total IGF from different scenarios with the same impacts, and the actual calculation may carry more digits than shown in this table, which may result in rounding differences when multiplying the IGFs and CCDPs.

The risk in FA 16 is dominated by fire scenarios that are modeled as control room abandonment scenarios. The core damage risk for control room abandonment is modeled as the set of operator actions required in the main control room prior to transferring command and control to the backup control panel, and the set of actions that need to occur at the backup control panel (i.e., panel 25-32) and locally to utilize the RCIC and LPCI Systems with control of SRVs. In the compliant case, the local actions that need to occur outside of the primary control station are considered as occurring at the primary control station or to be completely successful (i.e., are not required) for safe shutdown, and do not contribute to the risk of the compliant plant.

The following discussion applies to the risk significant fire scenarios in FA 03-0326 for the Unit 1, 2 and 3 compliant Fire PRA models:

Unit Scenario IGF CCDP1 CDF1 Unit 1 03-03.4001-C 1.31E-04 1.13E-01 1.48E-05 Unit 1 03-03.3000-T-3-G-2 3.62E-05 1.13E-01 4.10E-06 Unit 2 03-03.4001-C 1.31E-04 1.13E-01 1.48E-05 Unit 2 03-03.3000-T-3-G-2 3.62E-05 1.13E-01 4.10E-06 Unit 3 03-03.4001-C 1.31E-04 1.25E-01 1.64E-05 Unit 1 OSP (Offsite Power) 4.73E-02 1.00E-03 4.74E-05 Impact Unit 1 OSP and EHC Impact 6.02E-03 1.10E-03 6.62E-06 Unit 2 OSP Impact 4.73E-02 9.66E-04 4.57E-05 Unit 2 OSP and EHC Impact 6.02E-03 1.06E-03 6.39E-06 Unit 3 OSP Impact 4.73E-02 1.19E-03 5.65E-05 Note 1: The CCDP is an average value based on the total CDF and the total IGF from different scenarios with the same impacts, and the actual calculation may carry more digits than shown in this table, which may result in rounding differences when multiplying the IGFs and CCDPs.

The fire scenarios result in accident sequence GTRAN-5A, which is a general transient sequence. Accident sequence GTRAN-5A is an isolation accident (Power Conversion System not credited in the Fire PRA) with successful early high pressure injection from either the HPCI or RCIC Systems. Long term high pressure injection from the HPCI or RCIC System, or early suppression pool cooling fails, and Control Rod Drive (CRD) System fails (not credited in the Fire PRA). Manual depressurization with two SRVs at Heat Capacity Temperature Limit (HCTL) about four hours after the scram is successful and subsequent low pressure injection with either the RHR or Core Spray (CS) System fails.

In these fire scenarios, the SPC, LPCI, and CS Systems are failed due to loss of the Emergency Equipment Cooling Water (EECW) System to both RHR and CS Room Coolers. Both loops of the RHR System are failed due to a combination of fire induced and random failure of loss of power supplies to EECW pumps and failure of the pumps themselves. Off-site power is failed due to the fire; EECW Pumps A3 and C3 are failed due to the fire, and random failure to run of DG C which supplies power to EECW Pump B3 results in the loss of EECW. The loss of the E3-79

EECW System results in the loss of the NSCA credited path for Units 1 (LPCI Pump 1A), 2 (LPCI Pump 2D), and 3 (LPCI Pump 3B).

Core damage is caused by loss of injection and the RPV is at low pressure.

The OSP impact scenario risk is dominated by the high ignition frequency and the loss of offsite power. The loss of offsite power results in cutsets that are dominated by common cause failures of the emergency diesel generators.

The OSP and EHC impact scenario risk is dominated by the common cause failure of the MSIVs to fail to close, with the EHC system failed (which would normally isolate the steam line) due to the fire and common cause failures of the emergency diesel generators The following discussion applies to the risk significant fire scenarios in Fire Area 03-0325-01 for the Unit 1, 2, and 3 compliant Fire PRA model:

Unit Scenario IGF CCDP1 CDF1 Unit 3 03-03.022-BCHG-2 7.46E-05 1.05E-01 7.82E-06 Unit 1 25-1.005-CAB 9.08E-04 3.42E-03 3.10E-06 Unit 2 25-1.005-CAB 9.08E-04 3.19E-03 2.90E-06 Unit 3 25-1.005-CAB 9.08E-04 3.91E-03 3.55E-06 Note 1: The actual calculation may carry digits than shown in this table, which may result in rounding differences when multiplying the IGFs and CCDPs.

The fire scenario results in accident sequence GTRAN-7, which is a general transient sequence. Accident sequence GTRAN-7 is an isolation accident (PCS not credited in the Fire PRA) with all high pressure injection failed immediately after scram. Depressurization with two SRVs is successful. Low pressure injection from the RHR or CS System is successful but must be initiated within 30 minutes. Suppression pool cooling fails but decay heat removal with drywell sprays or the primary containment vent is successful. Without SPC, the Primary Containment Pressure Limit is reached in approximately 10 hours1.157407e-4 days 0.00278 hours 1.653439e-5 weeks 3.805e-6 months . The successful vent fails the RHR and CS Systems due to inadequate net positive suction head (NPSH). Drywell (DW) spray is not successful and late (post vent) low pressure injection from the CRD System (not credited in the Fire PRA), condensate, RHRSW, SDC, CS from CST, and RHR from CST fails. Core damage is caused by loss of injection and the RPV is at low pressure.

In these fire scenarios, the scram successfully occurs, the Power Conversion System (PCS) fails (not credited in the Fire PRA) and there are no stuck open relief valves. HPCI or RCIC is successful for at least 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months . Early suppression pool cooling is not successful or initiated in time to prevent exceeding HCTL and 190 °F in the suppression pool. Therefore, long term HPCI or RCIC is not successful. Manual depressurization is successful once. After depressurization, low pressure injection by RHR in the LPCI mode and CS are unsuccessful. Low pressure injection with standby coolant injection or condensate injection is unsuccessful.

RHR SPC fails due to a combination of fire induced and random failures of the RHRSW and EECW system. RHRSW provides cooling water to the RHR heat exchangers, and EECW provides cooling to the EDGs and RHR pump room coolers. The south EECW header is failed due to fire impacts to RHRSW pump D1 discharge valve. EECW Pump D3 is in standby and cannot be started. This results in a loss of EECW flow to the EDGs supporting the RHRSW pumps for RHR heat exchanger cooling on RHR SPC Loop II.

The EECW north header is available, but fails randomly, resulting in the loss of the EDGs supporting loop I RHR SPC. The total loss of EECW also results in loss of the RHR and E3-80

CS pump room coolers. Depressurization succeeds, but LPCI and CS are lost due to the loss of EECW, and the loss of RHRSW/EECW pumps precludes using standby coolant injection. Condensate injection is failed due to a fire induced loss of offsite power, resulting in a loss of injection.

Core damage occurs with the reactor at low pressure.

In this fire scenario, all high pressure injection is failed due to the fire affecting the HPCI steam supply valves, HPCI instrumentation, and HPCI suction and discharge valves. The RCIC System is failed due to the fire affecting the RCIC steam supply valves and instrumentation.

SPC Loop II is failed due to the fire affecting the RHR Pump D and the fire affecting the RHRSW Pumps B1 and off-site power failure in addition to random failure of DG C power supply for RHRSW Pump B2 for RHR Heat Exchanger B cooling. The loss of RHR Heat Exchanger B cooling results in the loss of the NSCA credited LPCI path using RHR Pump 3B.

SPC Loop I is failed due to the fire affecting the beakers that supply Reactor Motor Operated Valve (RMOV) Board 3D. This also results in the loss of Loop I SDC and RHRSW injection, and LPCI from CST.

The following discussion applies to the risk significant fire scenarios in FA 08 for the Unit 1, 2 and 3 compliant Fire PRA models The following discussion applies to the risk significant fire scenarios in Fire Area 25-01 for the Unit 1, 2, and 3 compliant Fire PRA model:

Unit Scenario IGF CCDP1 CDF1 Unit 1 08.001-CAB 6.07E-04 2.90E-02 1.76E-05 Unit 2 08.001-CAB 6.07E-04 3.59E-02 2.18E-05 Unit 3 08.001-CAB 6.07E-04 2.77E-02 1.68E-05 Unit 1 25-1.3000-T-12 2.06E-05 1.07E-01 2.20E-06 Unit 2 25-1.3000-T-12 2.06E-05 1.07E-01 2.20E-06 Unit 3 25-1.3000-T-12 2.06E-05 1.11E-01 2.29E-06 Note 1: The actual calculation may carry more digits than shown in this table, which may result in rounding differences when multiplying the IGFs and CCDPs.

In these fire scenarios, the scram successfully occurs, the PCS fails (not credited in the Fire PRA) and there are no stuck open relief valves. HPCI or RCIC is successful for at least 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months . Early suppression pool cooling is not successful or initiated in time to prevent exceeding HCTL and 190 °F in the suppression pool. Therefore, long term HPCI or RCIC is not successful. Manual depressurization is successful. After depressurization, low pressure injection by RHR in the LPCI mode and CS are unsuccessful. Low pressure injection with standby coolant injection or condensate injection is unsuccessful.

RHR SPC fails due to a combination of fire induced and random failures of the RHRSW and EECW system. RHRSW provides cooling water to the RHR heat exchangers, and EECW provides cooling to the EDGs and RHR pump room coolers. RHRSW to the Loop II RHR heat exchangers is failed due to fire impacts to RHRSW pump D2 and B2. Loop I RHR SPC is lost due to fire impacts to the South EECW header EECW pumps B3 and D3.

The north header is failed due to random failure of EDG 3EB for pump C3, and swing pump C1 is failed due to the fire, and two pumps are required for adequate flow from the EECW system. The loss of EECW fails the EDGs supporting the RHR pumps. The same E3-81

impacts to EECW results in the loss of room cooling for both loops of RHR LPCI and CS, and the loss of RHRSW/EECW pumps precludes using standby coolant injection.

Condensate in level control is failed due to fire impacts to offsite power, resulting in a total loss of injection.

Core damage occurs with the reactor at low pressure.

The fire scenarios result in accident sequence GTRAN-5A, which is a general transient sequence. Accident sequence GTRAN-5A is an isolation accident (i.e., PCS not credited in the Fire PRA) with successful early high pressure injection from either the HPCI or RCIC System.

Long term high pressure injection from the HPCI or RCIC System, or early suppression pool cooling fails, and the CRD System fails (not credited in the Fire PRA). Manual depressurization with two SRVs at HCTL about four hours after the scram is successful and subsequent low pressure injection with either the RHR or CS System fails.

In this fire scenario, Loop II of SPC, LPCI, and CS for Units 1 and 2 are failed due to the fire affecting the RHR Pumps B, D, and associated valves. Loop I for Unit 3 is lost due to the fire affecting the power from 4 kV Shutdown Board C and D to EECW Pumps B3 and D3, which supply RHR and CS Room Coolers. The credited NSCA path for Units 1 and 2 (RHR Pumps 1A and 2C) and the path for Unit 3 (RHR Pump 3B) is lost due to the loss RHR Room cooling of the credited Loop. Room cooling is failed due to a combination of fire induced and random failure. Specifically room cooling to Loop I for Units 1 (LPCI Pump 1A) and 2 (LPCI Pump 2C) and Loop II for Unit 3 (LPCI Pump 3B) is lost due to test and maintenance unavailability of EECW Pump A3 or C3 (i.e., one of the two NSCA credited and required EECW pumps).

Core damage is caused by loss of injection and the RPV is at low pressure.

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PRA RAI 19.b.01, Part a TVA previously responded to PRA RAI 19.b.01 [PRA RAI 19.01.b], Part a, by letter dated October 6, 2014 (CNL-14-172). During a December 2, 2014, conference call with the NRC, TVA agreed to supplement its response to PRA RAI 19.01.b, Part a to address additional benign ignition sources. As discussed during the conference call, TVA considers "relatively benign ignition sources" to be limited to junction box fires, cable fires caused by welding and cutting, self-ignited cable fires, and fixed ignition source scenarios that damage the source equipment only. The below revised response provides discussion of additional benign ignition sources.

The below revised response supersedes the previous response for PRA RAI 19.b.01, Part a in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE:

The treatment of risk significant self-ignited cable fire scenarios has been updated in the BFN fire modeling analysis to follow the guidance in Fire PRA FAQ 13-0005, as necessary to meet the plant risk objective. Based on risk contribution, the self-ignited cable tray fire scenarios are have been refined by an iterative process to reduce the risk contribution of these scenarios until the risk from these scenarios is not overly conservative. Self-ignited cable fires scenarios that were refined are no longer assumed to propagate beyond the initial tray, and therefore, the Fire PRA target damage set has been significantly reduced. As such, self-ignited cable fires are no longer expected todo not yield high risk estimates when compared to the overall plant risk.

The fire ignition frequency for junction box fires, cable fires caused by welding and cutting, and self-ignited cable fires are combined into single scenarios in the updated model as allowed by Fire PRA FAQ 13-0005. Refer to the TVA response to PRA RAI 01.r.01 in this enclosure for additional discussion on the treatment of junction box fires. The junction box fires and cable fires caused by welding and cutting fires initially utilize the same CCDP as the self-ignited cable fires, which is expected to bewas reduced by the Fire PRA FAQ 13-0005 update. This approach is consistent with Fire PRA FAQ 13-0006. Based on risk contribution, the junction box scenarios are refined by an iterative process to reduce the risk contribution of these scenarios until the risk from these scenarios is not overly conservative. Therefore, junction box fires are no longer expected toand cable welding and cutting fires do not yield high risk estimates when compared to the overall plant risk.

Fixed ignition source scenarios that damage the source equipment only represent the minimum risk impact for a fire originating in an individual fixed ignition source. Because these scenarios represent the minimum risk impact for an ignition source, they do not yield overly conservative risk results.

The treatment of self-ignited cable fires and junction boxesignition sources that are considered to be "relatively benign," as described above, is appropriate and will not be overly conservative in the compliant casedoes not yield overly conservative risk estimates that would lead to non-conservative estimates of delta risk. The final disposition of junction boxthese fire scenarios will beis reflected in the updated fire risk results that will be provided to the NRC after the Fire PRA is updated and additional quantification is performed in the TVA response to PRA RAI 24 Part A provided in Enclosure 1 to this letter.

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PRA RAI 21, Part d TVA previously responded to PRA RAI 21, Part d, by letter dated January 10, 2014 (CNL-14-001). The TVA response to PRA RAI 21, Part d is revised to more clearly define the Emergency High Pressure Makeup (EHPM) pump credit applied in the Fire PRA model.

The below revised response supersedes the previous response for PRA RAI 21, Part d in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE Part d.

On the event tree level, the Fire PRA model credits the EHPM system as a final high pressure injection system for all sequences that involve a loss of all other high pressure injection sources. To achieve an acceptable end state, decay heat removal must also be successful.

ThisThe final EHPM system is also credited in sequences where decay heat removal has failed, leading to primary containment failure, but only for the purpose of assessing a different level 1 plant damage state (i.e., containment fails before core uncovery). Similar but distinct fault tree models were developed to accommodate timing constraints for the initiation of the system. This is the only sequence dependent variable because the system does not depend on vessel depressurization, reactor building environment, or the suppression pool as a suction source.

These timing criteria were based on the structure of the general transient event tree that incorporated a split fraction for various success criteria timings.

The timing criteria were not based on any specific thermal-hydraulic analysis during the modeling of this initial design concept. System successes in these cases were judgments made in order to estimate the potential contribution of this system for these sequences. The four hour timing criterion was based on the timing value typically used in the PRA to separate initial and long term injection. The PRA definition of initial injection success was continued injection for at least four hours or condensate flood-up with a two hour post condensate flood-up injection that credits the EHPM pump. The next major timing criterion for the EHPM system occurs more than eight hours after the scram, and would be after normal injection was lost due to a successful primary containment vent. In this case, the EHPM pump's suction source would not be dependent on suppression pool temperature. Separate timing was not considered for this initiation action because it would not provide enough human error probability (HEP) improvement over the four hour case to warrant the additional model complexity.

Each EHPM system fault tree is connected to the PRA fault tree via the top logic. Each case includes the normal power supply dependency (i.e., 4kV Unit Board 1C for Unit 1, 4kV Unit Board 2C for Unit 2, and 4kV Unit Board 3C for Unit 3), DC control power, the suction supply dependency (i.e., the CST), an estimated test and maintenance unavailability, random check valve failure events, and failure to start and failure to run events. This suction supply dependency model also includes an operator action to refill the CST because it was assumed the CST would not have the necessary inventory to provide 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of makeup. For the four hour initiation case an additional alternate power source from the proposed supplemental diesel was built into the fault tree logic and includes an operator action to transfer to that power supply.

This additional alternate power source from the proposed supplemental diesel is also credited for a two hour post-core damage in vessel recovery with the EHPM pump in the LERF model. Because final design information is not available, all of these reliability numbers with the exception of the normal power supply were best estimates based on existing similar equipment. The normal power supply models were already in the internal events fault tree.

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The development of the system design information to support the PRA modeling was a joint effort between the BFN NFPA 805 site team and the PRA team.

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PRA RAI 24, Part b TVA previously responded to PRA RAI 24, Part b, by letter dated October 6, 2014 (CNL-14-172). TVA has revised the response to PRA RAI 24, Part b, to replace references to actions to be performed with references to actions that have been performed, revise the discussion of the total flooding system modification in the CSR because Modification 79 is not being installed as discussed in the revised TVA response to FPE RAI 11 in this enclosure, and correct references to other RAI responses that are revised in this enclosure.

The below revised response supersedes the previous response for PRA RAI 24, Part b in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE The following describes how each method (i.e., each bullet) will be addressed in the final composite analysis results provided in support of the LAR and the PRA that will be used at the beginning of the self-approval of post-transition changes:

x PRA RAI 01.f regarding the frequency of Main Control Board (MCB) scenarios: The frequency of MCB fires has been revised and will be included in the composite analysis provided in response to PRA RAI 24 Part a and the PRA that will be used at the beginning of the self-approval of post-transition changes.

x PRA RAI 01.h.ii regarding the frequency and severity factor of catastrophic turbine generator fires: The frequency and severity factor of catastrophic turbine generator fires will behas been revised and is included in the composite analysis provided in response to PRA RAI 24 Part a and the PRA that will be used at the beginning of the self-approval of post-transition changes.

x PRA RAI 01.o regarding treatment of dependency for LERF-related HFEs: Dependency between LERF and CDF actions will be included in the composite analysis provided in response to PRA RAI 24 Part a and the PRA that will be used at the beginning of the self-approval of post-transition changes.

x PRA RAI 01.r (as clarified by the revised TVA response to PRA RAI 01.r.01 in this enclosure) regarding treatment of junction box fires: The treatment of junction box fires is described in the revised TVA response to RAI 01.r.01 in this enclosure. Based on the technical justifications provided in the revised TVA response to RAI 01.r.01, the approach is being retained in the fire PRA. As stated in the revised TVA response to PRA RAI 19.b.01 in this enclosure, TVA has incorporated guidance from Fire PRA FAQs 13-0005 and 13-0006 to reduce the contribution of self-ignited cable fires and junction box fires and these fires are not expected to be significant or have been evaluated for further refinement.

x PRA RAI 01.s regarding use of quantitative screening criteria consistent with CC-II of SR QNS-C1 as clarified by RG 1.200, Revision 2: The quantitative screening criteria has been updated to be consistent with the criteria in NUREG/CR-6850 Task 7 and non-propagating fire scenarios that do not screen will beare included in the composite analysis provided in response to PRA RAI 24 Part a and the PRA that will be used at the beginning of the self-approval of post-transition changes.

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x PRA RAI 01.v regarding use of minimum joint HEPs: Minimum joint HEPs of 1E-05 for all combinations that do not contain long term decay heat removal actions or LERF actions and 1E-06 for those that do will beare included in the composite analysis provided in response to PRA RAI 24 Part a and the PRA that will be used at the beginning of the self-approval of post-transition changes.

x PRA RAI 10 regarding removal of credit for area-wide incipient detection in the auxiliary instrument rooms: Credit has been removed from the Fire PRA for area-wide incipient detection in the auxiliary instrument rooms and updated risk results will beare included in the composite analysis provided in response to PRA RAI 24 Part a and the PRA that will be used at the beginning of the self-approval of post-transition changes.

x PRA RAI 12 regarding scenario-specific timing for emergency depressurization dependent on both fire-induced and random failures: The Fire PRA will be revised to consider random failures of high pressure injection when determining the timing for emergency depressurization. This will beis included in the composite analysis provided in response to PRA RAI 24 Part a and the PRA that will be used at the beginning of the self-approval of post-transition changes.

x PRA RAI 20 (as clarified by PRA RAI 20.01) regarding credit for existing, nonfire-specific operator actions in the compliant plant: Credit will beis given for existing nonfire-specific operator actions taken both internal to and outside of the main control room in the Fire PRA post-transition and compliant plant models and updated results will beare included in the composite analysis provided in response to PRA RAI 24 Part a and the PRA that will be used at the beginning of the self-approval of post-transition changes.

x PRA RAI 22.01 regarding estimation of circuit failure probabilities: Updated results estimating the circuit failure probabilities using NUREG/CR-7150 will beare included in the composite analysis provided in response to PRA RAI 24 Part a and the PRA that will be used at the beginning of the self-approval of post-transition changes.

x FM RAI 01.g regarding treatment of cable spreading room oil spill fires: The detailed fire modeling analysis has been revised to include cable spreading room oil fires. The results of these fire scenarios will beare included in the composite analysis provided in response to PRA RAI 24 Part a and the PRA that will be used at the beginning of the self-approval of post-transition changes.

x FPE RAI 05 regarding the risk treatment of ERFBS [Electrical Raceway Fire Barrier System]: The 1-hour ERFBS without automatic suppression will beis treated as a Variance from Deterministic Requirement (VFDR) and resolved with the Fire Risk Evaluation Process. The results of these fire scenarios will beare included in the composite analysis provided in response to PRA RAI 24 Part a and the PRA that will be used at the beginning of the self-approval of post-transition changes.

x PRA RAI 04.01 regarding the credit for MCR abandonment due to loss of control:

Cognitive failure of the operators to abandon will beis included in the Fire PRA.

Updated results will beare included in the composite analysis provided in response to PRA RAI 24 Part a and the PRA that will be used at the beginning of the self-approval of post transition changes.

x PRA RAI 04.k.01 regarding dependencies between alternate shutdown actions:

Dependencies will beare included where necessary between alternate shutdown actions. Updated results will beare included in the composite analysis provided in E3-87

response to PRA RAI 24 Part a and the PRA that will be used at the beginning of the self-approval of post-transition changes.

x PRA RAI 04.l.01 regarding the modeling of random failure probabilities for the backup control panel shutdown path: Random failure probabilities for the backup control panel shutdown path will beare included in the Fire PRA. Updated results will beare included in the composite analysis provided in response to PRA RAI 24 Part a and the PRA that will be used at the beginning of the self-approval of post-transition changes.

x PRA RAI 10.c.01 regarding the unavailability and unreliability value applied to the total flooding, clean agent suppression system in the cable spreading room: Justification has been provided for the unavailability and the unreliability value applied as described in the TVA response to PRA RAI 10.c.01 in this enclosureModification 79 will not be installed as discussed in the revised response to FPE RAI 11 in this enclosure and has been removed from the Fire PRA.

x PRA RAI 19.b.01 regarding the apparent dominance of risk scenarios from normally, relatively benign ignition sources (e.g., junction boxes): The treatment of self-ignited cable fires has been updated to follow Fire PRA FAQ 13-0005 for risk significant cable fires as described in the TVA response to PRA RAI 1019.b.01 Part a in this enclosurein TVA letter dated October 6, 2014. Therefore, self-ignited cable fires are no longer expected to be risk significant. The fire ignition frequency of the junction box fires and self-ignited cable fires are combined into one scenario per the guidance of Fire PRA FAQ 13-0006. Because the junction box fires utilize the same conditional core damage probabilities as the self-ignited cable fires, junction box fires are no longer expected to be risk significant eitheror have been evaluated for further refinement. If junction box fires are significant, they will be investigated to determine if further refinement is needed.

Updated results will beare included in the composite analysis provided in response to PRA RAI 24 Part a and the PRA that will be used at the beginning of the self-approval of post-transition changes.

x FM RAI 01.01 regarding fire propagation in cable trays: As described in the TVA response to FM RAI 01.01 (in TVA letter dated June 13, 2014), TVA considered "immediately adjacent" trays consistent with the guidance in FAQ 08-0049. Ignition timing and flame propagation of adjacent stacks was modeled consistent with NUREG/CR-6850. This will behas been retained in the Fire PRA.

x FM RAI 02.01 regarding the damage delay time for cables in covered trays: As described in the TVA response to FM RAI 02.01 (in TVA letter dated June 13, 2014), all cables that use the delay time guidance in NUREG/CR-6850, Section Q.2.2, are qualified cables. Covered trays containing unqualified cables are credited with a delay time of four minutes. This four-minute delay time is based on the tests whose results are documented in NUREG/CR-0381 "A Preliminary Report on Fire Protection Research Program Fire Barriers and Fire Retardant Coatings Tests." This will behas been retained in the Fire PRA.

Each change that needs to be made is being tracked by the TVA commitment tracking system. As described in the TVA response to PRA RAI 11.b and 11.c (in the TVA letter dated January 14, 2014), a focused scope peer review will be performed prior to transition to NFPA 805. To ensure this peer review is performed, the TVA response to PRA RAI 11.b and 11.c added Implementation Item 47, to LAR Table S-3. The LAR table requires that certain items be completed prior to the implementation of the NFPA 805 fire protection E3-88

program. The response to PRA RAI 23.d (in the TVA letter dated March 14, 2014), as corrected in Enclosure 2 to this letter, further revised the proposed Implementation Item 47 provided in the response to PRA RAI 11.b and c to include the LERF Analysis (element LE-C6) as follows: "Perform a focused-scope peer review of the Fire PRA. The peer review will include, as a minimum, the following elements: Fire PRA Cable Selection and Location (CS), Human Reliability Analysis (HRA), Fire Risk Quantification (FQ), Uncertainty and Sensitivity Analysis (UNC), and LERF Analysis (element LE-C6)."

To provide assurance that the focused scope peer review findings will be resolved before self-approval of post-transition changes, this response to PRA RAI 24.b revises the proposed LAR, Table S-3 Implementation Item 47 to require resolution of any focused scope peer review findings as follows: "Perform a focused-scope peer review of the Fire PRA.

The peer review will include, as a minimum, the following elements: Fire PRA Cable Selection and Location (CS), Human Reliability Analysis (HRA), Fire Risk Quantification (FQ), Uncertainty and Sensitivity Analysis (UNC), and LERF Analysis (element LE-C6). Any focused scope peer review Finding level Facts & Observations (F&Os) will be resolved prior to self-approval of post-transition changes."

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PRA RAI 24, Part d TVA previously responded to PRA RAI 24, Part d, by letter dated October 6, 2014 (CNL-14-172). TVA has revised the response to PRA RAI 24, Part d, to revise the discussion of the total flooding system modification in the CSR because Modification 79 is not being installed, as discussed in the revised TVA response to FPE RAI 11 in this enclosure, and correct references to RAI responses in other TVA letters.

The below revised response supersedes the previous response for PRA RAI 24, Part d in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE The unavailability and reliability value applied to the total flooding, clean agent suppression system in the cable spreading room discussed in the TVA response to PRA RAI 10.c.01 in this enclosure, tThe treatment of junction box and self-ignited cable fires discussed in the TVA response to PRA RAI 19.b.01 in this eEnclosure 1 to TVA letter dated October 6, 2014, the treatment of fire propagation between trays discussed in the TVA response to Fire Modeling (FM) RAI 01.01 in TVA letter dated June 13, 2014, and damage timing associated with covered trays described in the TVA response to FM RAI 02.01 in TVA letter dated June 13, 2014, will behave been retained. The assumptions associated with each will be evaluated as part of the application of the PRA model. No other methods or weaknesses will be retained in the PRA that is used to estimate the change in risk of post-transition changes to support self-approval.

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Containment and Ventilation Branch (SCVB) RAI 01, Part a TVA previously responded to SCVB RAI 01, Part a, by letter dated June 13, 2014 (CNL-14-097). TVA identified an error in the original response with respect to the system flow test used to test the two heat exchangers. The June 13, 2014 letter described the test as being performed during a High Pressure Cooling Injection (HPCI) System flow surveillance, when in fact it was done during a Reactor Core Isolation Cooling (RCIC) System flow test.

The RCIC system was used during the test to supply a heat load for the heat exchanger test.

Heat load determination for the test is measured at the heat exchanger inlets and outlets and is not derived from the system supplying the heat. Therefore, the specific system used (i.e., HPCI or RCIC) is supplemental information in the description of the test and is not relevant to the method by which heat exchanger heat load is determined and the RAI response.

The below revised response supersedes the previous response for SCVB RAI 01, Part a in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

REVISED RESPONSE (a) Heat exchanger performance tests were conducted on Unit 3 Residual Heat Removal (RHR) heat exchangers 3A and 3C in January 2012. Test protocol followed the guidelines of Electric Power Research Institute (EPRI) TR-107397, "Service Water Heat Exchanger Testing Guidelines," dated March 1998 and EPRI NP-7552, "Heat Exchanger Performance Monitoring Guidelines," dated December 1991. These EPRI guidelines are consistent with the recommendations provided in Generic Letter (GL) 89-13, "Service Water System Problems Affecting Safety-Related Equipment."

A data collection device and temporary test instrumentation were installed to accurately measure RHR System and RHR Service Water (RHRSW) System flows and fluid temperatures at the inlet and outlet of the heat exchangers. The two heat exchangers were individually tested with the RHR System operating in the suppression pool cooling mode during a scheduled Reactor Core Isolation Cooling (RCIC)High Pressure Cooling Injection (HPCI) System quarterly flow surveillance test. Conducting the test in association with the RCICHPCI surveillance test is beneficial because exhaust steam from the RCICHPCI turbine elevates the suppression pool temperature (increasing the heat transfer rate) and improves test accuracy by maintaining a stable pool temperature during data collection. Multiple flow and temperature data points were recorded during a period of stable operation, which were then used to perform a heat balance calculation across both sides of the heat exchanger, yielding the heat transfer rate, Q. Utilizing Q, measured flows, and data from the heat exchanger manufacturers data sheet, an overall fouling resistance for each heat exchanger was determined.

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Modification 87 TVA previously revised LAR, Attachment S, Table S-2, Item 87 by letter dated September 16, 2014 (CNL-14-160). TVA has determined that an ERFBS installation is not feasible for cable PP626. Therefore the cable will be re-routed to resolve the separation issue. of this letter provides security-related markup pages of LAR, Table S-2 described in the revised discussion.

The revised description provided below supersedes the previous revision of Modification 87 in its entirety. The changes from the previous response are shown with deleted text struck through, inserted text in bold, underline, and a revision bar in the right margin.

Modification 87 Description of Modification:

"Enclose power cables PP626 and ES50-I in ERFBS [Electrical Raceway Fire Barrier System] in Fire Area 05."

Description of Revision to Modification:

LAR, Attachment S, Table S-2, item 87 is revised to "EncloseRe-route power cable PP626 in ERFBS inaway from Fire Area 05."

Justification TVA has determined that cable ES50-I is not located in FA 05 and therefore meets separation requirements without the ERFBS modification. TVA has also determined that an ERFBS is not feasible for cable PP626. Therefore, cable PP626 will be re-routed to resolve the separation issue.

VFDR, Recovery Action, and LAR, Attachment A Changes:

Associated VFDR-05-006 will be revised to delete reference to cable ES50-1. Resolution of the VFDR will not be affected.

Estimated Probabilistic Risk Impact:

This change may result in a decrease in riskCable PP626 will be routed in a manner that does not significantly affect fire risk.

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ENCLOSURE 4 Tennessee Valley Authority Browns Ferry Nuclear Plant, Units 1, 2, and 3 Description of Additional Changes Made to the Licensing Amendment Request This enclosure provides descriptions of changes made to the Browns Ferry Nuclear Plant (BFN)

NFPA 805 License Amendment Request (LAR) that were not described in previous TVA responses to NRC Requests for Additional Information (RAIs) and were not included in TVA letters dated May 30, 2014, "Update to the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187)," and September 16, 2014, "Update to the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187)."

The marked-up BFN NFPA 805 LAR pages provided in Enclosure 6 and Enclosure 7 of this letter are annotated to identify the changes associated with each of the descriptions provided below.

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Problem Event Report (PER) 872482 PER 872482 evaluated a self-identified incorrect reference. LAR Attachment A, "NEI 04-02 Table B-1 Transition of Fundamental Fire Protection Program & Design Elements,"

Attachment C, Table C-1, "NFPA 805 Ch 4 Compliance (NEI 04-02 Table B-3)," Attachment C, Table C-2, "NFPA 805 Required Fire Protection Systems and Features," and Attachment S, Table S-3, "Implementation items," incorrectly reference B22 911104 201 as the electronic document management system file designation for the engineering evaluation for the unprotected openings in 1-hour floor ceiling assemblies on Elevations 621.25 and 639, of the Reactor Buildings. The affected pages are revised to refer to the correct file designation of B22 911004 201. Enclosure 6 of this letter provides non security-related marked up pages showing the changes to LAR Attachment A, LAR Attachment C, Table C-2, and LAR Attachment S, Table S-3. Enclosure 7 of this letter provides security-related marked up pages showing the changes to LAR Attachment C, Table C-1.

PER 893663 PER 893663 evaluated self-identified errors in LAR Attachment A . The LAR Attachment A, compliance basis for Section 3.5.3, "[Water Supply Pump Code Requirements]," and Section 3.5.5, "[Water Supply Pump Separation Requirements]," describe the capacity of "2,250 gpm at 300 foot total head" as the rated capacity of the fire pumps. The capacity of "2,250 gpm at 300 foot total head" is actually the required flow rate, not the rated, i.e.,

nameplate, capacity of the fire pumps. The affected pages are revised to correct and clarify the characterization of the capacity of "2,250 gpm at 300 foot total head." Enclosure 6 of this letter provides non security-related marked up pages showing the changes made to LAR Attachment A.

PER 915193 TVA has determined that there are several documentation deficiencies related to calculation MDQ0009992012000104, BFN Scoping Fire Modeling Report, that require correction. The deficiencies evaluated by PER 915193 are:

1. Multiple transient fire scenarios that were located in high radiation areas were not walked down and therefore have no target failures in the fire scenario modeling database, SAFE.

Transient Fire Scenarios without targets should be reviewed to ensure appropriate target sets are included for each scenario.

2. Transient fire scenarios across all three units are inconsistent. For the transient scenario drawings in MDQ0009992012000104, Section 6, a transient scenario identified in one units transient scenarios drawing may not have been identified in a similar area in a different units transient scenario drawing.

3. Many transient fire scenarios identified in the fire scenario modeling database (SAFE) are not shown on a transient scenario drawing in MDQ0009992012000104, Section 6. There are also typographical errors identified for some transient scenario drawings in MDQ0009992012000104, Section 6.

4. Some transient fire scenario boundaries cross from one fire compartment boundary into another. For clarity and consistency it is recommended to subdivide these transient fire scenarios so that the floor area associated with any one fire scenario falls within a single fire compartment.

5. Six transient scenarios were found to be walked down with target failures and the target failures were not entered into the fire modeling database, SAFE. These fire scenarios are:

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01-04.3000-T-1-K, 01-05.3000-T-1-B, 01-05.3000-T-1-F, 03-01.3000-T-3-SW-541, 03-03.3000-T-3-M, and 03-03.3000-T-3-B.

6. Many ignition sources were found to contain oil but the associated fire scenarios did not analyze a bounding target set for an oil fire scenario. Oil fire scenarios for these ignition sources were not analyzed because they were not capable of creating a hot gas layer.

However this is a non-conservative assumption as other targets could still be damaged.

7. Automatic suppression is credited in multiple fire scenarios within the scoping fire modeling calculation (MDQ0009992012000104).

8. The documentation for development of fire scenarios in the Turbine Building needs improvement. Specifically the calculation should better document the process, references, and results for how Offsite Power and EHC target equipment/raceway locations were identified and how fire initiator impact to these Fire PRA targets were identified.

9. Some Fire PRA cable termination endpoint equipment does not have a fire zone assignment in the fire modeling database (SAFE). As such, the equipment could not be added to the fire scenario in the database. Cables were often manually added to the fire scenario to work around this in the past. For improved efficiency, the Fire PRA cable end point equipment should have fire zones assigned so that the equipment can be directly added to the fire scenario in the database (SAFE). of this letter provides non security-related marked up pages showing the changes made to LAR Table C-2. Enclosure 7 of this letter provides security-related marked up pages showing the changes made to LAR Table C-1.

PER 931983 Some NFPA 805 modifications install a one hour rated ERFBS in compartments that do not have a fire suppression system. In these cases, the modification is not deterministically compliant because the one hour barrier must be used with area wide detection and suppression. TVA has determined that calculation MDN0009992012000100, "Fire Risk Evaluation," Revision 4, lists three VFDRs are listed in Section 1.1.1 of the respective fire area evaluation as DETERMINISTICALLY RESOLVED by an ERFBS modification when they should have been listed as a RISK evaluation. The three affected VFDRs are:

x VFDR-05-0006 ERFBS Modification 87 Fault protection issue on 4Kv Sd Bd B x VFDR-21-0006 ERFBS Modification 91 Fault protection issue on 4Kv Sd Bd 3EC x VFDR 21-0007 ERFBS Modification 92 Fault protection issue on 4Kv Sd Bd 3ED of this letter provides security-related marked up pages showing the changes made to LAR Table C-1.

PER 940133 PER 940133 evaluated self-identified errors found during revision of calculation EDQ099920110010 "NFPA 805 - Nuclear Safety Capability Analysis." TVA determined that Variances From Deterministic Requirements (VFDRs) had not been written for the following 4 kiloVolt (kV) Shutdown Board (SDBD)/Fire Area (FA) combinations:

x 4kV SDBD 3ED in FA 01-01, x 4kV SDBD 3ED in FA 01-02 x 4kV SDBD 3ED in FA 01-03 x 4kV SDBD A in FA 01-05 x 4kV SDBD B in FA 01-05 E4-3

x 4kV SDBD C in FA 01-05 x 4kV SDBD 3EA in FA 03-02 x 4kV SDBD 3EC in FA 03-02 x 4kV SDBD 3EA in FA 03-03 x 4kV SDBD 3EC in FA 03-03 provides security-related marked up pages showing the changes made to LAR Attachment C, Table C-1.

PER 946868 PER 946868 evaluated the need for the corrective action to the Carbon Dioxide (CO2) system described in LAR Table S-3, Item 22. NFPA 805 LAR Table S-3 Item 22 states, in part: "Adjust CO2 discharge timer for the Control Building CO2 systems in the Computer Rooms 1, 2, and 3 and Auxiliary instrument Rooms 1,2 and 3 such that a CO2 design concentration of 50% is maintained for a minimum of 20 minutes." The 20-minute time period is defined as "soak time."

TVA has determined that manual CO2 suppressions in Fire Area (FA) 16 is not required.

Therefore, LAR Attachment C, Tables C-1 and C-2, and LAR Attachment S, Table S-3 have been revised to delete the manual carbon dioxide systems from the required FP systems lists and to delete the corrective action requiring adjustment of the CO2 discharge timer from Implementation Item 22.

TVA reviewed the following NFPA 805 analyses and verified that no credit was taken for manually activated CO2 systems in Fire Area 16:

x EEEs supporting fire area boundaries between FA 16 and other adjoining fire area x Other EEEs within FA 16 x Fire Modeling/PRA calculations x Fire Risk Evaluation for FA 16 Neither the code of record for these systems, nor the retroactive requirements of NFPA 12-2008 require this increase in soak time. Based on the lack of original installation testing documentation for these systems and the desire not to create a potentially hazardous, environment for post timer adjustment testing, alternative pathways for success have been identified via review of the LAR and associated documentation. In summary, after review of the LAR, existing EEEs, and Fire PRA analyses supporting the LAR, TVA has determined that the manual carbon dioxide suppression systems located in the Auxiliary Instrumentation Rooms and Computer Rooms (all within FA 16) are not required. Therefore, these systems should not be identified as "Required" and upgrades are not needed to support the NFPA 805 transition.

From the review of NFPA 805 analyses, TVA determined that corrective action described in LAR Implementation Item 22 to increase the soak time is not required. of this letter provides non security-related marked up pages showing the changes made to LAR, Attachment C, Table C-2 and LAR Attachment S, Table S-3. Enclosure 7 of this letter provides security-related marked up pages showing the changes to LAR Attachment C, Table C-1.

PER 956311 PER 956311 documents a typographical error in LAR Attachment G. The error occurred in the Actions description for VFDR-01-03-0051. The 1-BKR-070-0008 (Reactor Building Closed E4-4

Cooling Water (RBCCW) Pump 1B) is in Compartment 6B not 6A and 0-BKR-070-0011 (RBCCW Pump 1C) is in Compartment 6A, not Compartment 6B. Evaluation of LAR, Attachment G, also determined that Action for "0-43BU-211-000D/005 in EMERG at Compartment 5," should be deleted in the LAR Attachment G for the following Recovery Action IDs:

x RISK-RA-01-04-08 x RISK-RA-02-03-05 x DID-RA-02-03-11 x RISK-RA-04-04 The evaluation also determined that LAR, Attachment G required revision to delete "Turn off normal AC lights in the 3EB and 3ED Shutdown Board Room at switches located at the main entrance and next to the sliding fire door in the 3EB Shutdown Board Room." from Recovery Action IDs DID-RA-24-01 and DID -RA-24-02." of this letter provides security-related marked up pages showing the changes to LAR Attachment G, Table G-1.

PER 961102 During review of Fire Protection/Appendix R calculations, TVA discovered that some engineering evaluations had not been reviewed during the development of the NFPA 805 LAR.

HAI Report 0006-0006-000-001, "Browns Ferry Nuclear Plant Review of Existing Engineering Equivalency Evaluations," documents the review of existing BFN Fire Protection Engineering Equivalency Evaluations against the guidance defined in NEI 04-02, "Guidance for Implementing a Risk-Informed, Performance Based Fire Protection Program Under 10 CFR 50.48 (c)," as clarified by NRC/Industry Frequently Asked Questions (FAQs). of this letter provides non security-related marked up pages showing the changes made to LAR, Attachment A, "NEI 04-02 Table B-1 Transition of Fundamental Fire Protection Program and Design Elements." Enclosure 7 of this letter provides security-related marked up pages showing the changes to LAR Attachment C, Table C-1.

PER 965449 TVA determined that calculation MDQ099920110009, "NFPA 805 Transition - Fire Area Designation," was incorrectly referenced in some attachments within the LAR and supporting analyses. MDQ099920110009 evaluates the adequacy of fire barriers to meet the criteria of NFPA 805. Therefore, TVA has revised LAR Attachment C, Tables C-1 and C-2 to delete calculation MDQ099920110009 as appropriate. of this letter provides non security-related marked up pages showing the changes made to LAR, Attachment C, Table C-2. Enclosure 7 of this letter provides security-related marked up pages showing the changes to LAR, Attachment C, Table C-1.

PER 965486 TVA identified a discrepancy in LAR Attachment C, Table C-1 for Fire Area 13, Performance Goal "3. Decay Heat Removal." The Method of Accomplishment for Unit 3 Decay Heat E4-5

Removal is states, Decay heat removal is achieved through the use of the 3B train of RHR in the Suppression Pool Cooling mode using RHRSW pump B1. However, the NFPA 805 -

Nuclear Safety Capability Analysis calculation that forms the basis for this LAR statement lists Alternate Shutdown Cooling as the Unit 3 Decay Heat Removal method. Therefore, the LAR Attachment C, Table C-1Unit 3 Performance Goal is revised to read, Decay heat removal is achieved through the use of the 3B train of RHR in the Alternate Shutdown Cooling mode using RHRSW pump B1. of this letter provides security-related marked up pages showing the changes to LAR, Attachment C, Table C-1.

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LAR, Attachment S, Table S-2, Modification 82 Description of Modification:

"Modify power supply for condensate system flow controls 2(3)-FIC-2-29 and 2(3)-LIC- 2-3 to allow manual control of the valves for fires in the Auxiliary Instrument Rooms from the MCR."

Description of Revision to Modification:

LAR, Attachment S, Table S-2, item 82 is revised to "Modify condensate system flow controls 1,2,3 FIC 2-29 to function automatically and 1,2,3 LSV 2-3 to prevent flow diversion for fires in the Auxiliary Instrument Rooms."

Justification TVA determined that actions required for manual operation of the condensate system should be eliminated in order to reduce risk for fires in the Auxiliary Instrument rooms. This expanded scope requires modifications for Unit 1.

VFDR, Recovery Action, and LAR, Attachment A Changes:

This issue is not associated with any VFDRs.

Estimated Probabilistic Risk Impact:

This change is made specifically to reduce PRA risk. of this letter provides security-related marked up pages showing the changes to LAR Attachment S, Table S-2.

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LAR, Attachment S, Table S-2, Modification 93 Description of Modification:

"Install manual valves in the TB that allow the control air headers in the individual reactor buildings to be depressurized."

Description of Revision to Modification:

LAR, Attachment S, Table S-2, item 97 is revised to "Install a modification to allow operators to isolate control air to the individual reactor buildings."

Justification The description of the modification commitment is being changed to allow the use of existing valves by providing a means of operator access.

VFDR, Recovery Action, and LAR, Attachment A Changes:

This issue is not associated with any VFDRs.

Estimated Probabilistic Risk Impact:

This change is consistent with modeling of the feature in the PRA. of this letter provides security-related marked up pages showing the changes to LAR Attachment S, Table S-2.

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LAR, Attachment S, Table S-2, Modification 97 Description of Modification:

"Install air release valves at the discharge of the electric fire pumps per NFPA 20-1987, 4-3.5.2."

Description of Revision to Modification:

LAR, Attachment S, Table S-2, item 97 is deleted.

Justification During design review, TVA determined that the fire pumps and discharge piping upstream of the check valve are near the minimum level of the reservoir. Therefore the amount of air that can accumulate in the discharge piping is minimal. The NPFA code deviation will be dispositioned using an engineering evaluation VFDR, Recovery Action, and LAR, Attachment A Changes:

This issue is not associated with any VFDRs.

LAR, Attachment A, item 3.5.3 [Water Supply Pump Code Requirements] is changed to delete Modification 97 to address compliance with NFPA 20.

Estimated Probabilistic Risk Impact:

This modification is not related to the PRA. of this letter provides security-related marked up pages showing the changes to LAR Attachment S, Table S-2.

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LAR, Attachment S, Table S-2, Modification 98 Description of Modification:

"Install baffles on sprinkler heads in the control building that are less than 6 feet apart per NFPA 13-1985, 4-4.19."

Description of Revision to Modification:

LAR, Attachment S, Table S-2, item 98 is revised to "Implement modifications to correct separation problems for sprinkler heads in the control building that are less than 6 feet apart per NFPA 13-1985, 4-4.19."

Justification The description of the modification commitment is being changed to allow more options for achieving compliance with NFPA 13.

VFDR, Recovery Action, and LAR, Attachment A Changes:

This issue is not associated with any VFDRs.

Estimated Probabilistic Risk Impact:

This modification is not related to the PRA. of this letter provides security-related marked up pages showing the changes to LAR Attachment S, Table S-2.

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LAR, Attachment S, Table S-2, New Modification 105 As described under PER 940133, in this enclosure, TVA identified a fault protection/secondary fire issue that was overlooked in the earlier analysis. Fire damage to associated circuits on Shutdown Board A in Fire Area 01-05 causes fault protection issues when the ability to trip the associated load breaker is lost. TVA proposes a modification to resolve the new VFDR 01-05-0032. Modification 105 states: "Re-route or enclose in ERFBS the normal control power cable B651-IA for 4kV Shutdown Board A in Fire Area 01-05." This modification will not have significant effect on PRA risk quantification because secondary fire affects are not modeled in the PRA. of this letter provides security-related marked up pages showing the changes to LAR Attachment S, Table S-2.

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ENCLOSURE 5 Tennessee Valley Authority Browns Ferry Nuclear Plant, Units 1, 2, and 3 Matrix of Changes Made on Affected License Amendment Request Pages E5-1

License Amendment Request Change Matrix BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 107 Attachment A Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 893663 108 Attachment A Enclosure 6 March 14, 2014 letter, Enclosure 4 and March 14, 2014 letter Enclosure 4 and December 17, 2014 letter, Enclosure 4, Modification 97 December 17, 2014 letter, Enclosure 4, PER 893663 110 Attachment A Enclosure 6 December 17, 2014 letter, Enclosure 3, FPE RAI 04 120 Attachment A Enclosure 6 May 30, 2014 letter, TVA-1 September 16, 2014 letter, Attachment 1 125 Attachment A Enclosure 6 May 30, 2014 letter, TVA-2 126 Attachment A Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 872482 127 Attachment A Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 872482 129 Attachment A Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 961102 130 Attachment A Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 961102 211 Attachment B Enclosure 6 December 17, 2014 letter, Enclosure 3, SSA RAI 04 238 Table C-1 Enclosure 7 Editorial 243 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 961102 January 14, 2014 letter, FPE RAI 08 244 Table C-1 Enclosure 7 Revised to reflect latest risk results 249 Table C-1 Enclosure 7 Revised to reflect modification installed 250 Table C-1 Enclosure 7 Revised to reflect modification installed 258 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 940133 262 Table C-1 Enclosure 7 Editorial 268 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 961102 January 14, 2014 letter, FPE RAI 08 December 17, 2014 letter, Enclosure 4, PER 915193 NSCA model refinements E5-1

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 269 Table C-1 Enclosure 7 Revised to reflect latest risk results 272 Table C-1 Enclosure 7 Revised to reflect modification installed 278 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 940133 282 Table C-1 Enclosure 7 Editorial 286 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 NSCA model refinements 287 Table C-1 Enclosure 7 Revised to reflect latest risk results 294 Table C-1 Enclosure 7 NSCA Model Refinements 295 Table C-1 Enclosure 7 NSCA Model Refinements 296 Table C-1 Enclosure 7 Revised to reflect modification installed 301 Table C-1 Enclosure 7 Editorial 310 Table C-1 Enclosure 7 NSCA model refinements December 17, 2014 letter, Enclosure 4, PER 940133 314 Table C-1 Enclosure 7 Editorial 318 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 NSCA model refinements December 17, 2014 letter, Enclosure 4, PER 961102 January 14, 2014 letter, FPE RAI 08 319 Table C-1 Enclosure 7 Revised to reflect latest risk results 321 Table C-1 Enclosure 7 Revised to reflect modification installed 334 Table C-1 Enclosure 7 Revised to reflect modification installed 343 Table C-1 Enclosure 7 Editorial 347 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 872482 348 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 872482 December 17, 2014 letter, Enclosure 4, PER 915193 December 17, 2014 letter, Enclosure 4, PER 961102 E5-2

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 349 Table C-1 Enclosure 7 Revised to reflect latest risk results 352 Table C-1 Enclosure 7 NSCA model refinements 356 Table C-1 Enclosure 7 Revised to reflect modification installed 359 Table C-1 Enclosure 7 NSCA model refinements 360 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 940133 364 Table C-1 Enclosure 7 Editorial 367 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 872482 368 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 872482 369 Table C-1 Enclosure 7 Revised to reflect latest risk results 374 Table C-1 Enclosure 7 Editorial 381 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 961102 January 14, 2014 letter, FPE RAI 08 December 17, 2014 letter, Enclosure 4, PER 915193 382 Table C-1 Enclosure 7 Revised to reflect latest risk results 383 Table C-1 Enclosure 7 Revised to reflect modification installed 387 Table C-1 Enclosure 7 Revised to reflect modification installed 389 Table C-1 Enclosure 7 Revised to reflect modification installed 397 Table C-1 Enclosure 7 NSCA model refinements 401 Table C-1 Enclosure 7 Editorial 407 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 961102 January 14, 2014 letter, FPE RAI 08 408 Table C-1 Enclosure 7 Revised to reflect latest risk results 412 Table C-1 Enclosure 7 Revised to reflect modification installed E5-3

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 417 Table C-1 Enclosure 7 Revised to reflect modification installed 425 Table C-1 Enclosure 7 Editorial 430 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 September 16, 2014 letter, Attachment 2 431 Table C-1 Enclosure 7 Revised to reflect latest risk results 433 Table C-1 Enclosure 7 September 16, 2014 letter, Attachment 2 434 Table C-1 Enclosure 7 May 30, 2014 letter, TVA-4 436 Table C-1 Enclosure 7 September 16, 2014 letter, Attachment 2 441 Table C-1 Enclosure 7 May 30, 2014 letter, TVA-5 458 Table C-1 Enclosure 7 Revised to reflect modification installed 462 Table C-1 Enclosure 7 Editorial 466 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 January 14, 2014 letter, FPE RAI 08 September 16, 2014 letter, Attachment 2 December 17, 2014 letter, Enclosure 4, PER 961102 467 Table C-1 Enclosure 7 Revised to reflect latest risk results 470 Table C-1 Enclosure 7 Revised to reflect modification installed 486 Table C-1 Enclosure 7 NSCA model refinements 490 Table C-1 Enclosure 7 Editorial 493 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 495 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 872482 496 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 872482 December 17, 2014 letter, Enclosure 4, PER 915193 December 17, 2014 letter, Enclosure 4, PER 961102 497 Table C-1 Enclosure 7 Revised to reflect latest risk results 500 Table C-1 Enclosure 7 Revised to reflect modification installed E5-4

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 507 Table C-1 Enclosure 7 Editorial 510 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 511 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 872482 512 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 872482 513 Table C-1 Enclosure 7 Revised to reflect latest risk results 518 Table C-1 Enclosure 7 Editorial 524 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 January 14, 2014 letter, FPE RAI 08 May 30, 2014 letter, TVA-3 December 17, 2014 letter, Enclosure 4, PER 961102 525 Table C-1 Enclosure 7 Revised to reflect latest risk results 530 Table C-1 Enclosure 7 Revised to reflect modification installed 536 Table C-1 Enclosure 7 Editorial 541 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 January 14, 2014 letter, FPE RAI 08 December 17, 2014 letter, Enclosure 4, PER 961102 542 Table C-1 Enclosure 7 Revised to reflect latest risk results 543 Table C-1 Enclosure 7 Revised to reflect modification installed 544 Table C-1 Enclosure 7 Revised to reflect modification installed 554 Table C-1 Enclosure 7 NSCA model refinements 557 Table C-1 Enclosure 7 Revised to reflect modification installed May 30, 2014 letter, TVA-4 559 Table C-1 Enclosure 7 NSCA model refinements 560 Table C-1 Enclosure 7 May 30, 2014 letter, TVA-4 December 17, 2014 letter, Enclosure 4, PER 940133 564 Table C-1 Enclosure 7 Editorial E5-5

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 567 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 568 Table C-1 Enclosure 7 May 30, 2014 letter, TVA-3 January 14, 2014 letter, FPE RAI 08 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 961102 569 Table C-1 Enclosure 7 Revised to reflect latest risk results 570 Table C-1 Enclosure 7 Revised to reflect modification installed 574 Table C-1 Enclosure 7 Revised to reflect modification installed 582 Table C-1 Enclosure 7 Revised to reflect modification installed 585 Table C-1 Enclosure 7 Revised to reflect modification installed 587 Table C-1 Enclosure 7 September 16, 2014 letter, Attachment 1 589 Table C-1 Enclosure 7 Revised to reflect modification installed 590 Table C-1 Enclosure 7 NSCA model refinements 596 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 940133 600 Table C-1 Enclosure 7 Editorial 603 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 872482 605 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 872482 December 17, 2014 letter, Enclosure 4, PER 961102 606 Table C-1 Enclosure 7 Revised to reflect latest risk results 608 Table C-1 Enclosure 7 Revised to reflect modification installed 609 Table C-1 Enclosure 7 Revised to reflect modification installed 614 Table C-1 Enclosure 7 Editorial 616 Table C-1 Enclosure 7 Revised to reflect latest risk results 625 Table C-1 Enclosure 7 Editorial 626 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 E5-6

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page December 17, 2014 letter, Enclosure 4, PER 961102 627 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 961102 September 16, 2014 letter, Attachment 1 628 Table C-1 Enclosure 7 Revised to reflect latest risk results 641 Table C-1 Enclosure 7 Editorial 642 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 643 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 644 Table C-1 Enclosure 7 Revised to reflect latest risk results 653 Table C-1 Enclosure 7 Editorial 654 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 655 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 656 Table C-1 Enclosure 7 Revised to reflect latest risk results 663 Table C-1 Enclosure 7 Editorial 665 Table C-1 Enclosure 7 Revised to reflect latest risk results 673 Table C-1 Enclosure 7 NSCA Model Refinements 674 Table C-1 Enclosure 7 NSCA Model Refinements 678 Table C-1 Enclosure 7 Editorial 679 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 680 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 681 Table C-1 Enclosure 7 Revised to reflect latest risk results 682 Table C-1 Enclosure 7 Editorial 684 Table C-1 Enclosure 7 Revised to reflect modification installed 695 Table C-1 Enclosure 7 Editorial 696 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 698 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 699 Table C-1 Enclosure 7 Revised to reflect latest risk results E5-7

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 707 Table C-1 Enclosure 7 Editorial 708 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 710 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 711 Table C-1 Enclosure 7 Revised to reflect latest risk results 719 Table C-1 Enclosure 7 Editorial 720 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 721 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 3, FPE RAI 05 722 Table C-1 Enclosure 7 Revised to reflect latest risk results 723 Table C-1 Enclosure 7 Revised to reflect modification installed 725 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 3, FPE RAI 05 729 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965486 730 Table C-1 Enclosure 7 Editorial 731 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 961102 December 17, 2014 letter, Enclosure 4, PER 965449 732 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 961102 December 17, 2014 letter, Enclosure 3, FPE RAI 05 733 Table C-1 Enclosure 7 Revised to reflect latest risk results 735 Table C-1 Enclosure 7 Revised to reflect modification installed December 17, 2014 letter, Enclosure 3, FPE RAI 05 740 Table C-1 Enclosure 7 May 30, 2014 letter, TVA-4 744 Table C-1 Enclosure 7 Editorial 745 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 746 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 747 Table C-1 Enclosure 7 Revised to reflect latest risk results 753 Table C-1 Enclosure 7 Editorial 754 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 755 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 E5-8

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 756 Table C-1 Enclosure 7 Revised to reflect latest risk results 762 Table C-1 Enclosure 7 Editorial 763 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 961102 December 17, 2014 letter, Enclosure 4, PER 965449 764 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 765 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 961102 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 946868 December 20, 2013 letter, Enclosure 1, FM RAI 01.b.ii 766 Table C-1 Enclosure 7 Revised to reflect latest risk results 787 Table C-1 Enclosure 7 Revised to reflect modification installed 792 Table C-1 Enclosure 7 NSCA model refinements 808 Table C-1 Enclosure 7 Revised to reflect modification installed 814 Table C-1 Enclosure 7 Revised to reflect modification installed 831 Table C-1 Enclosure 7 NSCA model refinements 832 Table C-1 Enclosure 7 NSCA model refinements 833 Table C-1 Enclosure 7 NSCA model refinements 839 Table C-1 Enclosure 7 Revised to reflect modification installed 842 Table C-1 Enclosure 7 Revised to reflect modification installed 846 Table C-1 Enclosure 7 Revised to reflect modification installed 848 Table C-1 Enclosure 7 May 30, 2014 letter, TVA-5 851 Table C-1 Enclosure 7 May 30, 2014 letter, TVA-4 857 Table C-1 Enclosure 7 Editorial 858 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 961102 December 17, 2014 letter, Enclosure 4, PER 965449 859 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 860 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 E5-9

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 861 Table C-1 Enclosure 7 Revised to reflect latest risk results 868 Table C-1 Enclosure 7 Editorial 869 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 961102 December 17, 2014 letter, Enclosure 4, PER 965449 870 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 871 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 872 Table C-1 Enclosure 7 Revised to reflect latest risk results 878 Table C-1 Enclosure 7 Editorial 879 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 961102 December 17, 2014 letter, Enclosure 4, PER 965449 880 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 881 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 Revised to reflect latest PRA model 882 Table C-1 Enclosure 7 Revised to reflect latest risk results 889 Table C-1 Enclosure 7 Editorial 890 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 891 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 892 Table C-1 Enclosure 7 Revised to reflect latest risk results 899 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 940133 903 Table C-1 Enclosure 7 Editorial 904 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 905 Table C-1 Enclosure 7 September 16, 2014 letter, Attachment 1, Modification 92 and December 17, 2014 letter, Enclosure 4, PER 931983 906 Table C-1 Enclosure 7 Revised to reflect latest risk results 907 Table C-1 Enclosure 7 Revised to reflect modification installed 909 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 931983 Revised to reflect modification installed E5-10

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 913 Table C-1 Enclosure 7 Editorial 914 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 915 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 Revised to reflect latest PRA model 916 Table C-1 Enclosure 7 Revised to reflect latest risk results 925 Table C-1 Enclosure 7 Editorial 926 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 927 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 NSCA model refinements 928 Table C-1 Enclosure 7 Revised to reflect latest risk results 929 Table C-1 Enclosure 7 Revised to reflect modification installed 932 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 3, FPE RAI 05 938 Table C-1 Enclosure 7 Editorial 939 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 940 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 941 Table C-1 Enclosure 7 Revised to reflect latest risk results 946 Table C-1 Enclosure 7 Editorial 947 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 949 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 950 Table C-1 Enclosure 7 Revised to reflect latest risk results 955 Table C-1 Enclosure 7 Revised to reflect modification installed 957 Table C-1 Enclosure 7 Revised to reflect modification installed 961 Table C-1 Enclosure 7 Editorial 962 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 964 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 965 Table C-1 Enclosure 7 Revised to reflect latest risk results 970 Table C-1 Enclosure 7 Editorial E5-11

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 971 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 973 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 NSCA model refinements 974 Table C-1 Enclosure 7 Revised to reflect latest risk results 975 Table C-1 Enclosure 7 NSCA model refinements Revised to reflect modification installed 976 Table C-1 Enclosure 7 NSCA model refinements 980 Table C-1 Enclosure 7 Editorial 983 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 984 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 915193 985 Table C-1 Enclosure 7 Revised to reflect latest risk results 986 Table C-1 Enclosure 7 Revised to reflect modification installed 989 Table C-1 Enclosure 7 NSCA model refinements 995 Table C-1 Enclosure 7 Editorial 996 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 997 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 998 Table C-1 Enclosure 7 Revised to reflect latest risk results 1003 Table C-1 Enclosure 7 Editorial 1004 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 1005 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 1006 Table C-1 Enclosure 7 Revised to reflect latest risk results 1011 Table C-1 Enclosure 7 Editorial 1013 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 961102 1017 Table C-1 Enclosure 7 Editorial 1018 Table C-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 965449 1020 Table C-1 Enclosure 7 Revised to reflect latest risk results E5-12

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 1021 Table C-1 Enclosure 7 NSCA model refinements 1022 Table C-1 Enclosure 7 NSCA model refinements 1024 Table C-1 Enclosure 7 Revised to reflect modification installed 1027 Table C-2 Enclosure 6 January 14, 2014 letter, FPE RAI 08 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 961102 1028 Table C-2 Enclosure 6 January 14, 2014 letter, FPE RAI 08 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 915193 December 17, 2014 letter, Enclosure 4, PER 961102 NSCA model refinements 1029 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 965449 NSCA model refinements 1030 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 965449 NSCA model refinements January 14, 2014 letter, FPE RAI 08 December 17, 2014 letter, Enclosure 4, PER 961102 1031 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 872482 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 915193 December 17, 2014 letter, Enclosure 4, PER 961102 1032 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 872482 December 17, 2014 letter, Enclosure 4, PER 965449 1033 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 965449 January 14, 2014 letter, FPE RAI 08 December 17, 2014 letter, Enclosure 4, PER 961102 December 17, 2014 letter, Enclosure 4, PER 915193 E5-13

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 1034 Table C-2 Enclosure 6 January 14, 2014 letter, FPE RAI 08 September 16, 2014 letter, Attachment 2 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 961102 1035 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 965449 September 16, 2014 letter, Attachment 2 1036 Table C-2 Enclosure 6 January 14, 2014 letter, FPE RAI 08 December 17, 2014 letter, Enclosure 4, PER 961102 December 17, 2014 letter, Enclosure 4, PER 872482 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 915193 1037 Table C-2 Enclosure 6 May 30, 2014, letter, TVA-3 December 17, 2014 letter, Enclosure 4, PER 872482 December 17, 2014 letter, Enclosure 4, PER 965449 1038 Table C-2 Enclosure 6 January 14, 2014 letter, FPE RAI 08 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 961102 1039 Table C-2 Enclosure 6 May 30,2014 letter, TVA-3 January 14, 2014 letter, FPE RAI 08 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 961102 1040 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 965449 January 14, 2014 letter, FPE RAI 08 December 17, 2014 letter, Enclosure 4, PER 961102 December 17, 2014 letter, Enclosure 4, PER 872482 1041 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 961102 E5-14

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page September 16, 2014 letter, Attachment 1 1042 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 961102 1043 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 965449 1044 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 965449 1045 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 965449 December 17 2014 letter, Enclosure 3, FPE RAI 05 1046 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 3, FPE RAI 05 December 17, 2014 letter, Enclosure 4, PER 961102 December 17, 2014 letter, Enclosure 4, PER 965449 1047 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 961102 December 17, 2014, Enclosure 4, PER 946868 1048 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 961102 December 20, 2013 letter, Enclosure 1, FM RAI o1.b.ii December 17, 2014 letter, Enclosure 4, PER 965449 1049 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 965449 Editorial 1050 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 965449 1051 Table C-2 Enclosure 6 September 16, 2014 letter, Attachment 1, Modification 92 December 17, 2014 letter, Enclosure 4, PER 931983 December 17, 2014 letter, Enclosure 4, PER 965449 Revised to reflect latest PRA model 1052 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 3, FPE RAI 05 December 17, 2014 letter, Enclosure 4, PER 965449 1053 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 965449 1054 Table C-2 Enclosure 6 NSCA model refinements E5-15

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 915193 1055 Table C-2 Enclosure 6 December 17, 2014 letter, Enclosure 4, PER 965449 December 17, 2014 letter, Enclosure 4, PER 961102 1107 Table G-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 940133 1108 Table G-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 940133 1110 Table G-1 Enclosure 7 NSCA model refinements 1112 Table G-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 956311 1113 Table G-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 940133 1116 Table G-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 956311 1117 Table G-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 940133 NSCA model refinements 1118 Table G-1 Enclosure 7 NSCA model refinements 1119 Table G-1 Enclosure 7 NSCA model refinements December 17, 2014 letter, Enclosure 4, PER 940133 1121 Table G-1 Enclosure 7 September 16, 2014 letter, Attachment 1 1124 Table G-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 956311 May 30, 2014 letter, TVA-7 1127 Table G-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 956311 September 16, 2014 letter, Attachment 2, Modification 34 1129 Table G-1 Enclosure 7 September 16, 2014 letter, Attachment 1 1133 Table G-1 Enclosure 7 NSCA model refinements 1135 Table G-1 Enclosure 7 May 30, 2014 letter, TVA-6 1137 Table G-1 Enclosure 7 September 16, 2014 letter, Attachment 1 December 17, 2014 letter, Enclosure 4, PER 940133 1140 Table G-1 Enclosure 7 NSCA model refinements December 17, 2014 letter, Enclosure 4, PER 940133 E5-16

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 1142 Table G-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 956311 1168 Table G-1 Enclosure 7 NSCA model refinements 1179 Table G-1 Enclosure 7 NSCA model refinements 1181 Table G-1 Enclosure 7 May 30, 2014 letter, TVA-7 1183 Table G-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 940133 1185 Table G-1 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 956311 NSCA model refinements 1190 Table H-1 Enclosure 6 February 13, 2014 letter, Enclosure 1, FM RAI 02.e September 16, 2014, letter, Attachment 3 October 6, 2014, letter, Enclosure 1, PRA RAI 19.b.01, Part a December 20, 2013 letter, Enclosure 1, PRA RAI 01.r October 6, 2014, letter, Enclosure 1, PRA 01.r.01 1205 Attachment J Enclosure 6 January 10, 2014 letter, FM RAI 03.b.i as revised by March 14, 2014 letter, Enclosure 2, FM RAI 03.b.i 1242 Attachment L Enclosure 6 December 17, 2014 letter, Enclosure 3, FPE RAI 03 1243 Attachment L Enclosure 6 December 17, 2014 letter, Enclosure 3, FPE RAI 03 1291 Table S-2 Enclosure 7 Editorial 1295 Table S-2 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 940133 Editorial 1296 Table S-2 Enclosure 7 December 17, 2014 letter, Enclosure 4, PER 940133 1297 Table S-2 Enclosure 7 Editorial 1301 Table S-2 Enclosure 7 March 14, 2014 letter, Enclosure 4 December 17, 2014 letter, Enclosure 4, PER 940133 Editorial May 30, 2014 letter, TVA-8 1302 Table S-2 Enclosure 7 September 16, 2014 letter, Attachment 1 1303 Table S-2 Enclosure 7 September 16, 2014 letter, Attachment 1 E5-17

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 1305 Table S-2 Enclosure 7 September 16, 2014 letter, Attachment 2 1307 Table S-2 Enclosure 7 NSCA model refinements 1310 Table S-2 Enclosure 7 September 16, 2014 letter, Attachment 1 1312 Table S-2 Enclosure 7 NSCA model refinements 1313 Table S-2 Enclosure 7 March 14, 2014 letter, Enclosure 4 and September 16, 2014 letter, Attachment 1 September 16, 2014 letter, Attachment 2 1314 Table S-2 Enclosure 7 September 16, 2014 letter, Attachment 2 1315 Table S-2 Enclosure 7 September 16, 2014 letter, Attachment 1 September 16, 2014 letter, Attachment 2 1316 Table S-2 Enclosure 7 September 16, 2014 letter, Attachment 2 Editorial 1317 Table S-2 Enclosure 7 September 16, 2014 letter, Attachment 2 1318 Table S-2 Enclosure 7 September 16, 2014 letter, Attachment 2 March 14, 2014 letter, Enclosure 4 1319 Table S-2 Enclosure 7 September 16, 2014 letter, Attachment 1 March 14, 2014 letter, Response to FPE RAI 10 and FPE RAI 12, Part c and Enclosure 4 1320 Table S-2 Enclosure 7 December 17, 2014 letter, Enclosure 3, FPE RAI 10 December 17, 2014 letter, Enclosure 3, FPE RAI 11, Part b 1321 Table S-2 Enclosure 7 NSCA model refinements September 16, 2014 letter, Attachment 1 1322 Table S-2 Enclosure 7 December 17, 2014 letter, Enclosure 4, Modification 82 1323 Table S-2 Enclosure 7 September 16, 2014 letter, Attachment 1 as revised by December 17, 2014 letter, Enclosure 3 September 16, 2014 letter, Attachment 2 1324 Table S-2 Enclosure 7 September 16, 2014 letter, Attachment 1 1325 Table S-2 Enclosure 7 September 16, 2014 letter, Attachment 1 1326 Table S-2 Enclosure 7 March 14, 2014 letter, Enclosure 4 E5-18

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page December 17, 2014 letter, Enclosure 4, Modification 97 1327 Table S-2 Enclosure 7 December 17, 2014 letter, Enclosure 4, Modification 98 1328 Table S-2 Enclosure 7 September 16, 2014 letter, Attachment 2 1329 Table S-2 Enclosure 7 December 17, 2014, letter, Enclosure 4, New Modification 105 December 17, 2014 letter, Enclosure 3, FPE RAI 04 1336 Table S-3 Enclosure 6 December 17, 2014, Enclosure 4, PER 946868 1339 Table S-3 Enclosure 6 January 10, 2014 letter, Response to PRA RAI 14 as revised by August 29, 2014, letter, response to RAI 14.01 and October 6, 2014 letter, Enclosure 2 December 17, 2014 letter, Enclosure 4, PER 872482 December 17, 2014 letter, Enclosure 4, PER 961102 1340 Table S-3 Enclosure 6 January 10, 2014 letter, Response to FPE RAI 04 as revised by December 17, 2014 letter, Enclosure 3, FPE RAI 04 January 10, 2014 letter, Response to FM RAI 01.d.i January 14, 2014, letter, Response to PRA RAI 11.b and c as revised by March 14, 2014 letter response to PRA RAI 23.d and October 6, 2014 letter response to PRA RAI 24 Part b and December 17, 2014 letter, Enclosure 3, PRA RAI 11, Part a December 17, 2014, letter, Enclosure 3, FPE RAI 10.

1356 Table U-1 Enclosure 6 May 30, 2014 letter, TVA-9 1360 Table U-1 Enclosure 6 March 14, 2014 letter, PRA RAI 23.d May 30, 2014 letter, TVA-9 1378 Table U-1 Enclosure 6 May 30, 2014 letter, TVA-9 1379 Table U-1 Enclosure 6 May 30, 2014 letter, TVA-9 1381 Table U-1 Enclosure 6 May 30, 2014 letter, TVA-9 1385 Table U-1 Enclosure 6 May 30, 2014 letter, TVA-9 1386 Table U-1 Enclosure 6 May 30, 2014 letter, TVA-9 1387 Table U-1 Enclosure 6 January 10, 2014 letter, PRA RAI 23.i 1388 Table U-1 Enclosure 6 May 30, 2014 letter, TVA-9 1394 Table U-1 Enclosure 6 May 30, 2014 letter, TVA-9 E5-19

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 1406 Table U-1 Enclosure 6 May 30, 2014 letter, TVA-9 1407 Table U-1 Enclosure 6 May 30, 2014 letter, TVA-9 1443 Attachment V Enclosure 6 January 14, 2014 letter, PRA RAI 11.b and c as revised by:

March 14, 2014 letter, PRA RAI 23.d, October 6, 2014 letter, PRA RAI 24 Part b, and December 17, 2014 letter, Enclosure 3, PRA RAI 11, Part a December 17, 2014 letter, Enclosure 3, PRA RAI 05 1444 Attachment V Enclosure 6 Updated to reflect PRA results provided in December 17, 2014 letter, Enclosure 7, Attachment W 1445 Attachment V Enclosure 6 January 14, 2014 letter FPE RAI 09 1446 Attachment V Enclosure 6 March 14, 2014 letter FPE RAI 10 as modified by December 17, 2014 letter, Enclosure 3, FPE RAI 10 December 17, 2014 letter, Enclosure 3, FPE RAI 11, Part b 1447 Attachment V Enclosure 6 March 14, 2014 letter FPE RAI 10 as modified by December 17, 2014 letter, Enclosure 3, FPE RAI 10 December 17, 2014 letter, Enclosure 3, FPE RAI 11, Part b 1448 Attachment V Enclosure 6 March 14, 2014 letter FPE RAI 10 as modified by December 17, 2014 letter, Enclosure 3, FPE RAI 10 December 17, 2014 letter, Enclosure 3, FPE RAI 11, Part b December 17, 2014 letter, Enclosure 3, FPE RAI 05 1449 Table V-1 Enclosure 6 January 14, 2014 letter PRA RAI 11.a 1454 Table V-3 Enclosure 6 Editorial 1494 Table V-4 Enclosure 6 January 14, 2014 letter, Enclosure 1, PRA RAI 11.a 1497 Table V-4 Enclosure 6 January 14, 2014 letter, Enclosure 1, PRA RAI 11.a 1517 Table V-4 Enclosure 6 Corrected excluded ASSESSMENT exclusion per Fire PRA Summary Document 1526 Table V-4 Enclosure 6 Editorial 1527 Table V-4 Enclosure 6 Editorial 1532 Table V-7 Enclosure 6 Editorial 1533 Table V-7 Enclosure 6 Editorial E5-20

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 1535 Table V-7 Enclosure 6 Editorial 1536 Table V-7 Enclosure 6 Editorial 1537 Table V-7 Enclosure 6 Editorial 1538 Table V-7 Enclosure 6 Fire PRA Summary Notebook Editorial 1539 Table V-7 Enclosure 6 Editorial 1540 Table V-7 Enclosure 6 Editorial 1541 Table V-7 Enclosure 6 Editorial January 10, 2014 letter, Enclosure 1, PRA RAI 01.a 1542 Table V-7 Enclosure 6 January 10, 2014 letter, Enclosure 1, PRA RAI 01.a 1543 Table V-7 Enclosure 6 January 10, 2014 letter, Enclosure 1, PRA RAI 01.a Editorial 1544 Table V-7 Enclosure 6 Editorial 1545 Table V-7 Enclosure 6 March 14, 2014 letter, Enclosure 1, PRA RAI 01.f as revised by December 17, 2014 letter, Enclosure 3, PRA RAI 01, Part f 1546 Table V-7 Enclosure 6 March 14, 2014 letter, Enclosure 1, PRA RAI 01.f as revised by December 17, 2014 letter, Enclosure 3, PRA RAI 01, Part f Editorial 1547 Table V-7 Enclosure 6 Editorial 1548 Table V-7 Enclosure 6 March 14, 2014 letter, Enclosure 1, PRA RAI 01.f as revised by December 17, 2014 letter, Enclosure 3, PRA RAI 01, Part f March 14, 2014 letter, Enclosure 1, FPE RAI 11 December 17, 2014 letter, Enclosure 3, FPE RAI 10 December 17, 2014 letter, Enclosure 3, FPE RAI 11, Part b Editorial 1549 Table V-7 Enclosure 6 Editorial 1550 Table V-7 Enclosure 6 Editorial 1551 Table V-7 Enclosure 6 Editorial E5-21

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page 1552 Table V-7 Enclosure 6 Editorial 1553 Table V-7 Enclosure 6 Editorial 1554 Table V-7 Enclosure 6 Editorial March 14, 2014 letter, Enclosure 1, FPE RAI 11 1558 Table V-7 Enclosure 6 Editorial 1561 Table V-7 Enclosure 6 Editorial 1562 Table V-7 Enclosure 6 Editorial 1563 Table V-7 Enclosure 6 August 29, 2014 letter, Enclosure 1, PRA RAI 22.01 1564 Table V-7 Enclosure 6 August 29, 2014 letter, Enclosure 1, PRA RAI 22.01 January 14, 2014 letter PRA RAI 01.l 1565 Table V-7 Enclosure 6 January 14, 2014 letter PRA RAI 01.l 1567 Table V-7 Enclosure 6 Editorial January 10, 2014 letter, Enclosure 1, PRA RAI 01.m 1568 Table V-7 Enclosure 6 March 14, 2014 letter, Enclosure 1, PRA RAI 01.o Editorial 1569 Table V-7 Enclosure 6 Editorial 1570 Table V-7 Enclosure 6 Editorial February 13, 2014 letter, Enclosure 1, PRA RAI 01.p 1571 Table V-7 Enclosure 6 February 13, 2014 letter, Enclosure 1, PRA RAI 01.p 1572 Table V-7 Enclosure 6 Revised to reflect associated calculation Editorial December 20, 2013 letter, Enclosure 1, PRA 01.q 1573 Table V-7 Enclosure 6 December 20, 2013 letter, Enclosure 1, PRA 01.q Editorial 1574 Table V-7 Enclosure 6 Editorial 1575 Table V-7 Enclosure 6 Editorial 1576 Table V-7 Enclosure 6 Editorial E5-22

BFN Units 1, 2, and 3 NFPA 805 Transition CNL-14-208 Report Affected Page Enclosure Number Containing (of 1661 pages) Section Markup Source of Change(s) Incorporated on Page February 13, 2014 letter, Enclosure 1, PRA RAI 01.s 1577 Table V-7 Enclosure 6 January 10, 2014 letter PRA RAI 01.t Editorial 1578 Table V-7 Enclosure 6 January 10, 2014 letter PRA RAI 01.t January 10, 2014 letter PRA RAI 01.u Editorial 1579 Table V-7 Enclosure 6 Editorial February 13, 2014 letter, Enclosure 1, PRA RAI 01.s 1582 Table V-7 Enclosure 6 Editorial 1583 Table V-7 Enclosure 6 Updated to reflect latest PRA model Editorial 1584 Table V-7 Enclosure 6 Editorial 1585 Table V-7 Enclosure 6 Editorial 1586 Table V-7 Enclosure 6 Editorial 1587 Table V-7 Enclosure 6 Editorial 1588 Table V-7 Enclosure 6 Editorial 1589 Table V-7 Enclosure 6 Editorial 1590 Table V-7 Enclosure 6 Editorial 1591 Table V-7 Enclosure 6 Editorial 1592 Table V-7 Enclosure 6 Editorial 1593 Table V-7 Enclosure 6 Editorial 1594 Table V-7 Enclosure 6 Editorial 1596 Table V-7 Enclosure 6 Editorial 1601 - 1605 Attachment W Enclosure 7 Revised to reflect latest risk results.

1606 - 1654 Tables W-1 Enclosure 7 Pages replaced in their entirety with Tables showing changes reflecting the latest through W-10 risk results. In addition, Tables W-8, W-9, and W-10 are revised to reflect changes related to March 13, 2014 letter FPE RAI 13.

E5-23

ENCLOSURE 6 Tennessee Valley Authority Browns Ferry Nuclear Plant, Units 1, 2, and 3 Markups of License Amendment Pages - Non Security-Related The markups provided in this enclosure are based on TVA letter dated March 27, 2013, "License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants (2001 Edition) (Technical Specification Change TS-480)," (ADAMS Accession No. ML13092A393), Enclosure, "Browns Ferry Nuclear Plant Units 1, 2, and 3 NFPA 805 Transition Report," pages, as supplemented by TVA letter dated May 16, 2013, "Response to NRC Request to Supplement License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Plant, Units 1, 2, and 3 (TAC Nos. MF1185, MF1186, and MF1187)," (ADAMS Accession No. ML13141A291).

The markups show deleted text as struck out. Inserted text is shown in text boxes with arrows indicating where the text is to be inserted. References to the TVA submittal describing the changes are provided in text boxes located in the right margin of each page.

Contents:

Marked up pages showing changes to:

License Amendment Request (LAR), Attachment A, "NEI 04-02 Table B-1 Transition of Fundamental Fire Protection Program & Design Elements"

LAR, Attachment B, "NEI 04-02 Table B Nuclear Safety Capability Assessment -

Methodology Review"

LAR, Attachment C, "NEI 04-02 TABLE B FIRE AREA TRANSITION," Table C-2, "NFPA 805 Required Fire Protection Systems and Features"

LAR Attachment H, "NFPA 805 Frequently Asked Questions Summary Table,"

Table H-1, "NEI 04-02 FAQs Utilized in LAR Submittal"

LAR, Attachment J, "Fire Modeling Verification and Validation (V&V)," Table J-1, "V & V Basis for Fire Models / Model Correlations Used"

LAR, Attachment L, "NFPA 805 Chapter 3 Requirements for Approval (10 CFR 50.48(c)(2)(vii))"

LAR, Attachment S, "Modifications and Implementation Items," Table S-3, "Implementation Items"

LAR, Attachment U, "Internal Events PRA Quality," Table U-1, "Internal Events PRA Peer Review - Facts and Observations"

LAR, Attachment V, "Fire PRA Quality"

LAR, Attachment V, Table V-1, "List of N/A HLRs and SRs for the BFN Fire PRA Peer Review"

LAR, Attachment V, Table V-3, "Fire PRA Peer Review Facts and Observations (F&Os)

That Were Resolved In Follow-on Peer Review" CNL-14-208, Page E6-1 of 144

LAR, Attachment V, Table V-4, "Assessment of Supporting Requirements From Follow-on Peer Review"

LAR Attachment V, Table V-7, "BFN Fire PRA Follow-on Peer Review Facts and Observations (F&Os)"

CNL-14-208, Page E6-2 of 144

TVA BFN Attachment A - NEI 04-02 Table B-1 Transition of Fundament Fire Protection Program & Design Elements A. NEI 04-02 Table B-1 Transition of Fundamental Fire Protection Program & Design Elements 55 Pages Attached Page A-1 CNL-14-208, Page E6-3 of 144 BFN Units 1, 2, and 3 NFPA 805 Transition Report, Page 76 of 1661

Attachment A NEI 04-02 Table B-1 Transition of Fundamental Fire Protection Program & Design Elements Compliance NFPA 805 Ch. 3 Reference Requirements / Guidance Statement Compliance Basis Section 2.14 of the NRC Safety Evaluation dated March 31, 1993 states "The fire pumps take suction from a separate bay in the Intake Pumping-Station which is supplied from the Wheeler Reservoir. The Wheeler reservoir provides an unlimited supply of fire suppression water."

Section 3.0 of the NRC Safety Evaluation dated March 31, 1993 states "The licensee's Fire Protection Plan and Fire Hazards Analysis described in BFN-FPR was reviewed and found acceptable... Consequently, based on this SE and the SEs mentioned above, the staff concludes that TVA's fire protection program described by the BFN-FPR submitted on January 15, 1992, conforms with BTP CMEB 9.5-1 and is therefore acceptable. "

Current plant documentation (Fire Protection Report, drawings, calculations, specifications, etc.) was reviewed to determine that plant changes or modifications do not invalidate previous NRC approval.

References Document ID 0-FPR-VOLUME 1/PART 1 Rev. 14 [Section 9.3.11.B] - Fire Protection Plan 1992-1-15 [Section 9.3.11.B and Enclosure C.6.b(11)] - BFN-NRC, Browns Ferry Nuclear Plant - Fire Protection Report 1993-03-31 [Sections 1.0, 2.0, and 3.0] - NRC-BFN, Safety Evaluation for Fire Protection Program - Browns Ferry Nuclear Plant Units 1, 2 and 3 3.5.2 [Water Supply Tank Code 3.5.2* Complies BFN complies via Exception No. 1.

Requirements] The tanks shall be interconnected such that fire pumps can take suction from either or both. A failure in one tank or its piping shall not allow both The BFN fire pumps take suction from the Wheeler Reservoir. Two tanks to drain. The tanks shall be designed in accordance with NFPA 22, independently separated fire water pumping trains are provided and each Standard for Water Tanks for Private Fire Protection. train is capable of providing 100% of the requirements for safety-related areas. The connections of each fire water pumping train with the yard Exception No. 1: Water storage tanks shall not be required when fire main loop is separated with sectionalizing valves between connections.

pumps are able to take suction from a large body of water (such as a The electric motor-driven fire pumps and diesel-driven fire pump are lake), provided each fire pump has its own suction and both suctions and adequately separated and each fire pump has its own suction. Electric pumps are adequately separated. motor-driven fire pumps are located in the intake pumping station and the diesel fire pump is located in a building adjacent to gate 2 on the Exception No. 2: Cooling tower basins shall be an acceptable water Condenser Circulating Water System cold water channel.

source for fire pumps when the volume is sufficient for both purposes and water quality is consistent with the demands of the fire service.

References Document ID BFN-50-7026 Rev. 7 [Sections 3.7.1.1, 3.7.2.1 and 3.7.2.2] - High Pressure Fire Protection System December 17, 2014 letter, Enclosure 4, PER 893663 3.5.3 [Water Supply Pump 3.5.3* Complies with 3 electric motor drive fire pumps and 1 diesel engine driven fire pump, Code Requirements] Fire pumps, designed and installed in accordance with NFPA 20, Use of EEEEs each rated at 2,250 gpm at 300 foot total head are provided at BFN.

Standard for the Installation of Stationary Pumps for Fire Protection, shall be provided to ensure that 100 percent of the required flow rate and Only one fire pump is necessary to supply 100 percent of the required flow pressure are available assuming failure of the largest pump or pump required to provide rate and pressure assuming failure of the largest pump or pump power power source. source.

The fire pumps at BFN are evaluated to be compliant with NFPA 20 - 1987 and NFPA 20 - 1999 as shown in the referenced Code Compliance Evaluation.

Fire Safety Analysis Data Manager (4.129) TVA Browns Ferry Run: 03/23/2013 10:31 Page: 31 of 55 CNL-14-208, Page E6-4 of 144 BFN Units 1, 2, and 3 NFPA 805 Transition Report, Page 107 of 1661

Attachment A NEI 04-02 Table B-1 Transition of Fundamental Fire Protection Program & Design Elements March 14, 2014 letter Enclosure 4 Compliance and NFPA 805 Ch. 3 Reference Requirements / Guidance Statement Compliance Basis December 17, 2014 Item for Implementation: letter, Enclosure 4, Modification 97 Corrective actions were identified in the Code Compliance Evaluation.

These corrective actions are identified in Modifications 96 and 97 in Table S-2 of Attachment S and Implementation Item 17 in Table S-3 of Attachment S.

References Document ID 0-FPR-VOLUME 1/PART 1 Rev. 14 [Section 4.4.1(a)] - Fire Protection Plan MDQ099920100008 Rev. 1 [All] - NFPA-20 Code Compliance Evaluation - High Pressure Fire Pumps 3.5.4 [Water Supply Pump 3.5.4 Complies A diesel engine-driven fire pump is provided in addition to the 3 electric Diversity and Redundancy] At least one diesel engine-driven fire pump or two more seismic Category motor-driven fire pumps. As stated in BFN-50-7026, the diesel driven I Class IE electric motor-driven fire pumps connected to redundant Class pump can supply 100 percent of the required flow rate and pressure, IE emergency power buses capable of providing 100 percent of the meeting the requirement of this section.

required flow rate and pressure shall be provided.

References Document ID 0-FPR-VOLUME 1/PART 1 Rev. 14 [Section 4.4.1(a)] - Fire Protection Plan BFN-50-7026 Rev. 7 [Section 3.7.2.1] - High Pressure Fire Protection System December 17, 2014 letter, Enclosure 4, PER 893663 3.5.5 [Water Supply Pump 3.5.5 Complies with The BFN design includes three electric fire pumps in a common Intake Separation Requirements] Each pump and its driver and controls shall be separated from the Previous Pumping Station. The diesel fire pump is located in a separate structure remaining fire pumps and from the rest of the plant by rated fire barriers. Approval on the CCW cold water channel. TVA has previous approval for the three electric motor-driven fire pumps located in the Intake Pumping Station to not be separated from each other by fire barriers.

The TVA letter to the NRC entitled "Browns Ferry Nuclear Plant - Fire Protection Report", dated January 15, 1992, Section 4.4.1 of the Fire Protection Plan states The system is supplied raw water by three motor driven vertical turbine pumps. rated at 2250 gpm each at 300 foot total head and located in the Intake Pumping Station, and by one diesel-engine

-driven vertical turbine fire pump rated at 2250 gpm at 300 foot total head and located in a building adjacent to gate structure 2 on the CCW cold water channel.

This discussion is also supplemented by Enclosure 2 which is entitled It should be noted that the rating of "2250 gpm at Comparison of Browns Ferry Nuclear Plant Fire Protection Program to 300 foot total head" is the capacity at which each NRC Branch Technical Position CMEB 9.5-1." Section C.6.b(6)(a) & (b) pump is required to provide water to the high states "Three 100 percent electrical fire pumps are located inside the pressure fire protection system, not the rated Intake Pumping Station. A 100 percent diesel engine driven fire pump is capacity of each pump. provided remote from the electric fire pumps and is located in a separate building adjacent to gate structure 2 on the cold water channel."

The NRC Safety Evaluation dated March 31, 1993 states in Section 1.0, "The following SE documents the staff's review of the Fire Protection Plan and Fire Hazards Analysis described by the BFN-FPR. The BFN-FPR establishes the TVA fire protection program for BFN... As part of its BFN-FPR submittal, the licensee has compared their new Fire Protection Fire Safety Analysis Data Manager (4.129) TVA Browns Ferry Run: 03/23/2013 10:31 Page: 32 of 55 CNL-14-208, Page E6-5 of 144 BFN Units 1, 2, and 3 NFPA 805 Transition Report, Page 108 of 1661

Attachment A NEI 04-02 Table B-1 Transition of Fundamental Fire Protection Program & Design Elements Compliance NFPA 805 Ch. 3 Reference Requirements / Guidance Statement Compliance Basis References Document ID 1988-08-03 [Enclosure 3, Section 3.2.2] - Browns Ferry Nuclear Plant (BFN) - Summary of Deviations from National Fire Protection Association (NFPA) Code 1989-11-03 [Section 7.0] - NRC-BFN, Supplemental Safety Evaluation on Post-Fire Safe Shutdown System and Final Review of the National Fire Protection Association Code Deviations - Browns Ferry Nuclear Plant, Unit 2, (EDMS Number A02 891108 003)

BFN-50-7026 Rev. 7 [Section 3.7.2.2 and 3.7.2.3] - High Pressure Fire Protection System 3.5.8 [Water Supply Pressure 3.5.8 Complies with HPFP System pressure is maintained by an interconnection to the raw Maintenance Limitations] A method of automatic pressure maintenance of the fire protection water Use of EEEEs service water system at approximately 50 psig. The referenced NFPA 20 -

system shall be provided independent of the fire pumps. 1987 Edition Code Compliance Evaluation identified that a fire pump is often utilized to maintain pressure when the raw service water system cannot meet the total system demands.

Item for Implementation:

Implement corrective actions required to ensure that pressure is maintained in the fire protection system during normal operation without using a fire pump. See Implementation Item 44 in Table S-3 of Attachment S. December 17, 2014 References Document ID letter, Enclosure 3, Modification Item 106 in Table S-2 FPE RAI 04 BFN-50-7026 Rev. 7 [Section 3.7.2.2] - High Pressure Fire Protection System MDQ099920100008 Rev. 1 [All] - NFPA-20 Code Compliance Evaluation - High Pressure Fire Pumps 3.5.9 [Water Supply Pump 3.5.9 Complies An alarm is provided on the fire alarm panel in the control room to indicate Operation Notification] Means shall be provided to immediately notify the control room, or other operation of the fire pumps.

suitable constantly attended location, of operation of fire pumps.

References Document ID MDQ099920100008 Rev. 1 [Att D 7-4.7, Att. C 9-4.3.1] - NFPA-20 Code Compliance Evaluation - High Pressure Fire Pumps 3.5.10 [Water Supply Yard 3.5.10 Complies with An underground yard fire main loop is installed at BFN to furnish Main Code Requirements] An underground yard fire main loop, designed and installed in accordance Use of EEEEs anticipated water requirements.

with NFPA 24, Standard for the Installation of Private Fire Service Mains and Their Appurtenances, shall be installed to furnish anticipated water The underground yard main at BFN is evaluated to be in compliance with requirements. NFPA 24 - 1984 Edition as shown in the referenced Code Compliance Evaluation.

References Document ID MDQ099920100011 Rev. 1 [All] - NFPA-24 Code Compliance Evaluation Fire Safety Analysis Data Manager (4.129) TVA Browns Ferry Run: 03/23/2013 10:31 Page: 34 of 55 CNL-14-208, Page E6-6 of 144 BFN Units 1, 2, and 3 NFPA 805 Transition Report, Page 110 of 1661

Attachment A NEI 04-02 Table B-1 Transition of Fundamental Fire Protection Program & Design Elements Compliance NFPA 805 Ch. 3 Reference Requirements / Guidance Statement Compliance Basis 3.9.1 [Fire Suppression System 3.9.1* N/A General requirements. The requirements of this Section are addressed in Code Requirements] If an automatic or manual water-based fire suppression system is required Sections 3.9.1(1) through 3.9.1(4).

to meet the performance or deterministic requirements of Chapter 4, then the system shall be installed in accordance with the appropriate NFPA standards including the following:

3.9.1 [Fire Suppression System 3.9.1 (1) NFPA 13, Standard for the Installation of Sprinkler Systems Complies with Sprinkler systems at BFN are evaluated to be in compliance with NFPA 13 Code Requirements] (1) Use of EEEEs - 1985, 1987, 1991 and 2002 editions as shown in the referenced Code Compliance Evaluations.

Partial suppression is provided for fire zones 01-01, 01-02, 01-03, 01-04, 02-01, 02-02, 02-03, 02-04, 03-01 and 03-02 in the Reactor Building.

These sprinkler systems are adequate as evaluated in MDQ099920110009.

See Table C-2 of the LAR for required systems.

Item for Implementation: and September 16, 2014 letter, Attachment 1 Corrective actions were identified in the Code Compliance Evaluations.

These corrective actions are identified in Modifications 98, 99, 100 and 101 in Table S-2 of Attachment S and Implementation Item 20 in Table S-2 3 of Attachment S.

References Document ID May 30, 2014 letter MDQ099920100005 Rev. 1 [All] - NFPA-13 Code Compliance Evaluation - 1985 Edition TVA-1 MDQ099920110001 Rev. 1 [All] - NFPA-13 Code Compliance Evaluation - 1987 Edition MDQ099920110002 Rev. 1 [All] - NFPA-13 Code Compliance Evaluation - 1991 Edition MDQ099920110003 Rev. 1 [All] - NFPA-13 Code Compliance Evaluation - 2002 Edition MDQ099920110009 Rev. 1 - NFPA-805 Transition - Fire Area Designation 3.9.1 [Fire Suppression System 3.9.1 (2) NFPA 15, Standard for Water Spray Fixed Systems for Fire Complies with Water spray systems at BFN are evaluated to be in compliance with NFPA Code Requirements] (2) Protection Use of EEEEs 15 - 1985, or NFPA 15 - 2001 as shown in the referenced Code Compliance Evaluations.

See Table C-2 of the LAR for required systems.

Item for Implementation:

Corrective actions were identified in the Code Compliance Evaluations.

These corrective actions are identified in Modification 102 in Table S-2 of Attachment S and Implementation Item 21 in Table S-3 of Attachment S.

References Document ID MDQ099920100007 Rev. 1 [All] - NFPA-15 Code Compliance Evaluation - 1985 Edition MDQ099920110004 Rev. 1 [All] - NFPA-15 Code Compliance Evaluation - 2001 Edition Fire Safety Analysis Data Manager (4.129) TVA Browns Ferry Run: 03/23/2013 10:31 Page: 44 of 55 CNL-14-208, Page E6-7 of 144 BFN Units 1, 2, and 3 NFPA 805 Transition Report, Page 120 of 1661

Attachment A NEI 04-02 Table B-1 Transition of Fundamental Fire Protection Program & Design Elements Compliance NFPA 805 Ch. 3 Reference Requirements / Guidance Statement Compliance Basis References Document ID MDQ099920100004 Rev. 0 [Attachment E; Section 4.3.3.4] - NFPA-12 Code Compliance Evaluation 3.10.9 [Gaseous Suppression 3.10.9 Complies The possibility of thermal shock was considered in the design of the CO2 System Cooling The possibility of secondary thermal shock (cooling) damage shall be fire suppression systems.

Considerations] considered during the design of any gaseous fire suppression system, but particularly with carbon dioxide.

1992-1-15 [Enclosure 2 Section C.6.e] - BFN-NRC, Browns Ferry Nuclear Plant (BFN) - Fire Protection Report (FPR)

References Document ID May 30, 2014 letter MDQ099920100004 Rev. 0 [Supplement Section C.6.e] - NFPA-12 Code Compliance Evaluation TVA-2 3.10.10 [Gaseous Suppression 3.10.10 N/A Carbon Dioxide is the product of decomposition and will not react with the System Decomposition Issues] Particular attention shall be given to corrosive characteristics of agent atmosphere and form corrosive products.

decomposition products on safety systems.

According to the NFPA Fire Protection Handbook, 2008 edition, CO2 does not leave residue. The lack of residue eliminates the possibilities for corrosion on equipment in areas protected by CO2 suppression systems.

References Document ID NFPA Fire Protection Handbook Rev. 2008 Ed. [Chapter 1, Section 17] -

3.11 Passive Fire Protection 3.11 Passive Fire Protection Features. N/A Section Heading.

Features. This section shall be used to determine the design and installation requirements for passive protection features. Passive fire protection features include wall, ceiling, and floor assemblies, fire doors, fire dampers, and through fire barrier penetration seals. Passive fire protection features also include electrical raceway fire barrier systems (ERFBS) that are provided to protect cables and electrical components and equipment from the effects of fire.

3.11.1 Building Separation. 3.11.1 Building Separation. Complies with All major buildings within the power block are separated from each other Each major building within the power block shall be separated from the Use of EEEEs by barriers having a fire resistance rating of 3-hours, or are evaluated to others by barriers having a designated fire resistance rating of 3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months or be equivalent to a 3-hour rating.

by open space of at least 50 ft (15.2 m) or space that meets the requirements of NFPA 80A, Recommended Practice for Protection of BFN utilizes the exception to this section.

Buildings from Exterior Fire Exposures.

Exception: Where a performance-based analysis determines the Evaluation MDQ099920110009 documents the acceptability of the adequacy of building separation, the requirements of 3.11.1 shall not separation of the Refuel Floor from the Reactor Building, Control Building, apply. and Turbine Building, the separation of the Transformers in the Yard from adjacent structures (Turbine and Reactor Buildings), the separation of the chillers from the Unit 1 and 2 Diesel Generator Building, and the separation of the miscellaneous structures in the yard and buildings containing safe shutdown equipment.

References Document ID 0-FPR-VOLUME 1/PART 2 Rev. 14 [Section 6.0] - The Fire Protection Report, Fire Hazards Analysis MDQ099920110009 Rev. 1 - NFPA-805 Transition - Fire Area Designation Fire Safety Analysis Data Manager (4.129) TVA Browns Ferry Run: 03/23/2013 10:31 Page: 49 of 55 CNL-14-208, Page E6-8 of 144 BFN Units 1, 2, and 3 NFPA 805 Transition Report, Page 125 of 1661

Attachment A NEI 04-02 Table B-1 Transition of Fundamental Fire Protection Program & Design Elements Compliance NFPA 805 Ch. 3 Reference Requirements / Guidance Statement Compliance Basis 3.11.2 Fire Barriers. 3.11.2 Fire Barriers. Complies Interior and exterior walls are designed to provide the fire-resistance rating Fire barriers required by Chapter 4 shall include a specific fire-resistance shown on the fire compartmentation drawings. Floor and ceilings are rating. Fire barriers shall be designed and installed to meet the specific fire designed to maintain vertical fire separation as required.

resistance rating using assemblies qualified by fire tests. The qualification fire tests shall be in accordance with NFPA 251, Standard Methods of The fire-resistance rating for reinforced concrete is influenced by the Tests of Fire Endurance of Building Construction and Materials, or ASTM thickness, moisture and air content, type of aggregate, workmanship, E 119, Standard Test Methods for Fire Tests of Building Construction and direction of loading, and level of stress as determined from tests Materials. performed in accordance with ASTM E119.

Gypsum Wallboard. Plaster, and Lath These wall assemblies are tested and approved by a nationally recognized testing laboratory and tested in accordance with ASTM E119.

Concrete Block Concrete block assemblies are tested by a nationally recognized testing laboratory in accordance with applicable industry standards. UL category "Concrete Blocks (CAZT)" covers solid and hollow blocks of Portland cement and fine and course aggregates. Concrete blocks produced in accordance with UL 618 (which uses UL 263 as fire test) are included in this category. Other blocks are classified by UL on the basis of fire tests conducted in accordance with UL 263, which is equivalent to ASTM E119 according to the NFPA Fire Protection Handbook, 2008 edition.

References Document ID DS-M17.3.3 Rev. 2 [Section 3] - Fire Barrier Standard December 17, 2014 NFPA Fire Protection Handbook Rev. 2008 Ed. [2-67] - letter, Enclosure 4, PER 872482 Complies with Evaluation MDQ099920110009 documents the acceptability of the fire Use of EEEEs barriers for each fire area at BFN.

FHA Section 4.3 documents the acceptability of unrated features in the barriers between the Main Steam and Feedwater Piping Tunnel and the Reactor Buildings.

MDQ0100930090 documents the acceptability of protection provided for cables within conduits that are embedded in concrete in Fire Areas 17, 18 and 19.

MDQ0303880381 and MDQ2303880380 document the acceptability of structural steel protection in the Control Building, Reactor Buildings and Intake Pumping Station.

MDQ0009992012000109 documents the acceptability of protection provided for cables within conduits that are embedded in concrete in Shutdown Board Rooms 2A and 2B.

B22 911004 201 MDQ0009992012000112 documents the acceptability of the seismic gaps to maintain the three-hour barrier between buildings.

RIMS B22 911104 201 documents the acceptability of unsealed penetrations in the floor/ceiling assemblies in the RWCU valve room on Fire Safety Analysis Data Manager (4.129) TVA Browns Ferry Run: 03/23/2013 10:31 Page: 50 of 55 CNL-14-208, Page E6-9 of 144 BFN Units 1, 2, and 3 NFPA 805 Transition Report, Page 126 of 1661

Attachment A NEI 04-02 Table B-1 Transition of Fundamental Fire Protection Program & Design Elements Compliance NFPA 805 Ch. 3 Reference Requirements / Guidance Statement Compliance Basis Elevation 621.25 and the RWCU filter/demineralizer room on Elevation 639.

MDQ0009992012000113 documents the acceptability of an opening between Fire Areas 16 and 26 that has been sealed with concrete block.

References Document ID 0-FPR-VOLUME 1/PART 2 Rev. 14 [Section 4.3] - The Fire Protection Report, Fire Hazards Analysis 1992-1 BFN-NRC, Browns Ferry Nuclear Plant - Fire Protection Report 1993-03 NRC-BFN, Safety Evaluation for Fire Protection Program - Browns Ferry Nuclear Plant Units 1, 2 and 3 MDQ0009992012000109 Rev. 0 [All] - Shutdown Board Rooms 2A and 2B Effect of Fire on Embedded Conduits Evaluation MDQ0009992012000112 Rev. 0 [All] - Evaluation of Seismic Gaps between Buildings MDQ0009992012000113 Rev. 0 [All] - Fire Area 16 Fire Barrier Wall Opening Evaluation MDQ0100930090 Rev. 1 [All] - Effect of Fire on Embedded Conduits Serving Equipment in Fire Areas 17 & 19 & 18 MDQ0303880381 Rev. 1 [All] - Fire Hazard Analysis for the Structural Steel on Elevation 593 of the Control Building B22 911004 201 December 17, 2014 MDQ099920110009 Rev. 1 [All] - NFPA-805 Transition - Fire Area Designation letter, Enclosure 4, MDQ2303880380 Rev. 0 [All] - Fire Hazard Analysis for the Structural and Supporting Steel in the Unit 2 Reactor Building and Intake Pumping Station PER 872482 RIMS B22 911104 201 Rev. 7/6/1988 [All] - Engineering Evaluation for the Unprotected Openings in 1-Hour Floor Ceiling Assemblies on Elevations 621.25' and 639' of the Reactor Buildings 3.11.3 Fire Barrier 3.11.3* Fire Barrier Penetrations. Complies with Penetrations in fire barriers are provided with listed fire-rated door Penetrations. Penetrations in fire barriers shall be provided with listed fire-rated door Use of EEEEs assemblies or listed rated fire dampers of 11/2 or 3-hour rating. The fire assemblies or listed rated fire dampers having a fire resistance rating resistive ratings of the door assemblies and fire dampers are consistent consistent with the designated fire resistance rating of the barrier as with the fire resistive ratings of the associated barriers. Further discussion determined by the performance requirements established by Chapter 4. is provided in Sections 3.11.3(1) through 3.11.3(3).

(See 3.11.3.4 for penetration seals for through penetration fire stops.)

Passive fire protection devices such as doors and dampers shall conform The exception to this section is utilized at BFN.

with the following NFPA standards, as applicable: (see subsections)

Evaluation SL-010944 (R06 120309 483) documents the acceptability of Exception: Where fire area boundaries are not wall-to-wall, floor-to-ceiling the fire barriers in the Intake Pumping Station.

boundaries with all penetrations sealed to the fire rating required of the boundaries, a performance-based analysis shall be required to assess the adequacy of fire barrier forming the fire boundary to determine if the barrier will withstand the fire effects of the hazards in the area. Openings in fire barriers shall be permitted to be protected by other means as acceptable to the AHJ.

References Document ID 0-FPR-VOLUME 1/PART 2 Rev. 14 [Section 3.3.4] - The Fire Protection Report, Fire Hazards Analysis MDQ099920110009 Rev. 1 - NFPA-805 Transition - Fire Area Designation SL-010944 (R06 120309 483) Rev. 0 - Fire Protection Engineering Evaluation for Intake Pumping Station Fire Barriers Fire Safety Analysis Data Manager (4.129) TVA Browns Ferry Run: 03/23/2013 10:31 Page: 51 of 55 CNL-14-208, Page E6-10 of 144 BFN Units 1, 2, and 3 NFPA 805 Transition Report, Page 127 of 1661

Attachment A NEI 04-02 Table B-1 Transition of Fundamental Fire Protection Program & Design Elements Compliance NFPA 805 Ch. 3 Reference Requirements / Guidance Statement Compliance Basis References Document ID MDQ099920100015 Rev. 1 [All] - NFPA-80 Code Compliance Evaluation MDQ099920100016 Rev. 1 [All] - NFPA-90A Code Compliance Evaluation 3.11.4 Through Penetration 3.11.4* Through Penetration Fire Stops. N/A General requirements. The requirements of this Section are addressed in Fire Stops. Through penetration fire stops for penetrations such as pipes, conduits, Sections 3.11.4(a) and 3.11.4(b).

bus ducts, cables, wires, pneumatic tubes and ducts, and similar building service equipment that pass through fire barriers shall be protected as follows.

3.11.4 Through Penetration 3.11.4* (a) The annular space between the penetrating item and the Complies with Penetration seals are evaluated to be in compliance with this section in Fire Stops. (a) through opening in the fire barrier shall be filled with a qualified fire- Use of EEEEs the referenced Engineering Evaluations and Fire Protection Report resistive penetration seal assembly capable of maintaining the fire Volume 1 Part 2.

resistance of the fire barrier. The assembly shall be qualified by tests in accordance with a fire test protocol acceptable to the AHJ or be protected by a listed fire-rated device for the specified fire-resistive period.

References Document ID 0-FPR-VOLUME 1/PART 2 Rev. 14 [Section 3.3.4] - The Fire Protection Report, Fire Hazards Analysis December 17, 2014 1992-1 BFN-NRC, Browns Ferry Nuclear Plant - Fire Protection Report letter, Enclosure 4, 1993-03 NRC-BFN, Safety Evaluation for Fire Protection Program - Browns Ferry Nuclear Plant Units 1, 2 and 3 PER 961102 MDQ0009992012000112 Rev. 0 [All] - Evaluation of Seismic Gaps between Buildings MDN2100890068 - Pressure/Fire Boundary Seal Design R25654623 MDN2100890081 - Pressure/Fire Boundary Seal Design B25932153 & B25934165 MDQ0100890003 Rev. 0 [All] - Evaluation of Building Gap and Seal Details MDQ0100890018 - Analysis of SBO, NSR, and UNK Appendix R Penetrations MDQ0100940033 Rev. 1 [All] - Appendix R - Welded Plate Penetration Evaluation MDQ0100890035 - Fire Boundary Seal Design for Gypsum Walls MDQ0100980006 Rev. 3 [All] - Engineering Evaluation of Penetration Seals MDQ0100950013 - Appendix R Bolted Plate Penetration Seal Evaluation MDQ099920110009 Rev. 1 - NFPA-805 Transition - Fire Area Designation RIMS B22 911004 003 Rev. 7/27/1988 [All] - Engineering Evaluation of the Bus Duct Penetrations SL-010944 (R06 120309 483) Rev. 0 - Fire Protection Engineering Evaluation for Intake Pumping Station Fire Barriers 3.11.4 Through Penetration 3.11.4* (b) Conduits shall be provided with an internal fire seal that has an Complies with Conduit seals are evaluated to be in compliance with this section in Fire Stops. (b) equivalent fire-resistive rating to that of the fire barrier through opening fire Use of EEEEs accordance with the referenced Engineering Evaluation and the Fire stop and shall be permitted to be installed on either side of the barrier in a Protection Report, Volume 1, Part 2.

location that is as close to the barrier as possible.

Exception: Openings inside conduit 4 in. (10.2 cm) or less in diameter MDQ1100890013 - Fire Barrier Seal Design for C16171606 December 17, 2014 shall be sealed at the fire barrier with a fire-rated internal seal unless the MDQ2100890004 - Pressure/Fire Boundary Seal Design R26215118 letter, Enclosure 4, conduit extends greater than 5 ft (1.5 m) on each side of the fire barrier. In MDQ2100890066 - Pressure/Fire Boundary Seal Design R25654061 PER 961102 this case the conduit opening shall be provided with noncombustible MDQ2100890079 - Pressure/Fire Boundary Seal Design S26213862 material to prevent the passage of smoke and hot gases. The fill depth of MDQ3100890074 - Pressure/Fire Boundary Seal Design 035834321 the material packed to a depth of 2 in. (5.1 cm) shall constitute an MDQ3100890080 - Pressure/Fire Boundary Seal Design R35654243 acceptable smoke and hot gas seal in this application. MDQ3100890094 - Pressure/Fire Boundary Seal Design R35652034 MDQ3100890105 - Pressure/Fire Boundary Seal Design R35652027 MDQ3100920093 - Cable Trays Fire Seal LDSE Fire Safety Analysis Data Manager (4.129) TVA Browns Ferry Run: 03/23/2013 10:31 Page: 53 of 55 CNL-14-208, Page E6-11 of 144 BFN Units 1, 2, and 3 NFPA 805 Transition Report, Page 129 of 1661

Attachment A NEI 04-02 Table B-1 Transition of Fundamental Fire Protection Program & Design Elements Compliance NFPA 805 Ch. 3 Reference Requirements / Guidance Statement Compliance Basis References Document ID 0-FPR-VOLUME 1/PART 2 Rev. 14 [Section 3.3.4] - The Fire Protection Report, Fire Hazards Analysis MDN2100890043 - Pressure/Fire Boundary Seal Design C25932433 1992-1 BFN-NRC, Browns Ferry Nuclear Plant - Fire Protection Report MDQ003988224 - Electrical Conduit Fire Seal Assessment (EC-1) 1993-03 NRC-BFN, Safety Evaluation for Fire Protection Program - Browns Ferry Nuclear Plant Units 1, 2 and 3 December 17, 2014 MDQ0100980006 Rev. 3 [All] - Engineering Evaluation of Penetration Seals letter, Enclosure 4, PER 961102 SL-010944 (R06 120309 483) Rev. 0 - Fire Protection Engineering Evaluation for Intake Pumping Station Fire Barriers MDQ3100910304 - Internal Conduit Fire Seal-Promaflex) 3.11.5 Electrical Raceway Fire 3.11.5* Electrical Raceway Fire Barrier Systems (ERFBS). Complies with ERFBS are evaluated to be in compliance with this section in accordance Barrier Systems (ERFBS). ERFBS required by Chapter 4 shall be capable of resisting the fire effects Use of EEEEs with the referenced Engineering Evaluations and the Fire Protection of the hazards in the area. ERFBS shall be tested in accordance with and Report, Volume 1, Part 2.

shall meet the acceptance criteria of NRC Generic Letter 86-10, Supplement 1, "Fire Endurance Test Acceptance Criteria for Fire Barrier Systems Used to Separate Safe Shutdown Trains Within the Same Fire Area." The ERFBS needs to adequately address the design requirements and limitations of supports and intervening items and their impact on the fire barrier system rating. The fire barrier systems ability to maintain the required nuclear safety circuits free of fire damage for a specific thermal exposure, barrier design, raceway size and type, cable size, fill, and type shall be demonstrated.

Exception No. 1: When the temperatures inside the fire barrier system exceed the maximum temperature allowed by the acceptance criteria of Generic Letter 86-10, "Fire Endurance Acceptance Test Criteria for Fire Barrier Systems Used to Separate Redundant Safe Shutdown Training Within the Same Fire Area," Supplement 1, functionality of the cable at these elevated temperatures shall be demonstrated. Qualification demonstration of these cables shall be performed in accordance with the electrical testing requirements of Generic Letter 86-10, Supplement 1, Attachment 1, "Attachment Methods for Demonstrating Functionality of Cables Protected by Raceway Fire Barrier Systems During and After Fire Endurance Test Exposure."

Exception No. 2: ERFBS systems employed prior to the issuance of Generic Letter 86-10, Supplement 1, are acceptable providing that the system successfully met the limiting end point temperature requirements as specified by the AHJ at the time of acceptance.

References Document ID 0-FPR-VOLUME 1/PART 1 Rev. 14 [Table 9.3.11.H] - Fire Protection Plan 1992-1 BFN-NRC, Browns Ferry Nuclear Plant - Fire Protection Report 1993-03 NRC-BFN, Safety Evaluation for Fire Protection Program - Browns Ferry Nuclear Plant Units 1, 2 and 3 2006-11-15 [All] - TVA BFN Technical Specification (TS) No. 459, Request for an Appendix R License Amendment 2007-04-25 [All] - NRC-BFN, Browns Ferry Nuclear Plant, Units 1, 2 and 3 Issuance of Amendments Regarding Revision to Appendix R License Conditions To Reflect Three-Unit Operation (EDMS Number L44 070511 005)

MDQ0100950053 Rev. 0 [All] - Thermo-Lag 330-1 Engineering Evaluations Fire Safety Analysis Data Manager (4.129) TVA Browns Ferry Run: 03/23/2013 10:31 Page: 54 of 55 CNL-14-208, Page E6-12 of 144 BFN Units 1, 2, and 3 NFPA 805 Transition Report, Page 130 of 1661

TVA BFN Attachment B - NEI 04-02 Table B-2 Nuclear Safety Capability Assessment Methodology Review B. NEI 04-02 Table B Nuclear Safety Capability Assessment - Methodology Review 101 Pages Attached Page B-1 CNL-14-208, Page E6-13 of 144 BFN Units 1, 2, and 3 NFPA 805 Transition Report, Page 132 of 1661

Attachment B NEI 04-02 Table B-2 Nuclear Safety Capability Assessment - Methodology Review 2.4.2.2 Nuclear Safety Capability Circuit Analysis NEI 00-01 Ref. NEI 00-01 Guidance 3.5.2.3 Circuit Failures Due to a Hot Short [C, A Hot Short on Ungrounded Circuits Ungrounded Circuits]

In the case of an ungrounded circuit, a single hot short may be sufficient to cause a spurious operation. A single hot short can cause a spurious operation if the hot short comes from a circuit from the positive leg of the same ungrounded source as the affected circuit. In reviewing each of these cases, the common denominator is that in every case, the conductor in the circuit between the control switch and the start/stop coil must be involved.

Figure 3.5.2-5 depicted below shows a typical ungrounded control circuit that might be used for a motor-operated valve. However, the protective devices and position indication lights that would normally be included in the control circuit for a motor-operated valve have been omitted, since these devices are not required to understand the concepts being explained in this section. In the discussion provided below, it is assumed that a single fire in a given fire area could cause any one of the hot shorts depicted. The discussion provided below describes how to address the impact of these cable faults on the operation of the equipment controlled by this circuit.

[Refer to NEI 00-01 Rev. 1 for Figure 3.5.2-5]

Hot short No. 1: A hot short at this location from the same control power source would energize the close relay and result in the undesired closure of a motor operated valve.

Hot short No. 2: A hot short at this location from the same control power source would energize the open relay and result in the undesired opening of a motor operated valve.

Applicability Applicable Alignment Statement Alignment Basis Reference Aligns with Intent Hot shorts on ungrounded circuits were considered to occur either from EDQ099920110010 Rev. 1 [Sections 4.0 and 6.6.3] - NFPA 805 -

internal cable wire-to-wire shorts or external cable-to-cable shorts. For cable Nuclear Safety Capability Analysis failures on ungrounded circuits, the methodology assumes the hot short would EPM-DP-EP-004 Rev. 2 [Section 5.2 and Appendix A - Sections 3.0 have sufficient potential to cause a spurious operation of the component. In & 3.2] - Post Fire Safe Shutdown Cable Identification (EDMS specific cases, the effect of a fire-induced hot short may not be assumed if a Number R06 121128 917) detailed evaluation demonstrates that no aggressor hot short source NEI 00-01 Rev. 1 [Appendix C - Section C.4] - Guidance for Post-conductors are routed in the same raceways as the target conductor. These Fire Safe Shutdown Circuit Analysis evaluations are documented in the calculation entitled, "NFPA 805 - Nuclear Safety Capability Analysis." December 17, 2014 letter, Enclosure 3, The BFN Treatment of hot shorts on ungrounded circuits does not specifically align with this guidance. Two types of cable hot short conditions are SSA RAI 04 considered to be of sufficiently low likelihood that they are not assumed credible, except for analysis involving high/low pressure interface components . NUREG/CR-7150, Vol. 1 (EPRI Report 1026424), Joint Assessment of in accordance with NEI 00-01. These hot short exceptions are 3 phase AC Cable Damage and Quantification of Effect from Fire (JACQUE-FIRE) was power circuit cable-to-cable proper phase sequence faults and 2-wire issued in October 2012. In this report, irrespective of high/low pressure ungrounded DC circuit cable-to-cable proper polarity faults. interface consideration, the Phenomena Identification and Ranking Table (PIRT) panel concluded the spurious operation of a three-phase AC motor due to proper polarity hot shorts on three-phase power cabling is incredible and the spurious operation of DC compound-wound motors due to proper polarity hot shorts in the motive/power cabling is incredible. As defined in the report, "the term "incredible" used in conjunction with the phenomenon of a fire-induced circuit failure, signifies the PIRT panel's conclusion that the event cannot occur. In these cases, the PIRT panel could find no evidence of the phenomenon ever occurring, and there were no credible engineering principles or technical argument to support its happening during a fire. Any likelihood value assigned to these types of phenomena would have little meaning." Therefore, TVA does not consider these hot short type circuit failures as credible based on the PIRT panel conclusions.

Fire Safety Analysis Data Manager (4.129) TVA Browns Ferry Run: 03/23/2013 19:16 Page: 79 of 101 CNL-14-208, Page E6-14 of 144 BFN Units 1, 2, and 3 NFPA 805 Transition Report, Page 211 of 1661

Security-Related Information - Withhold Under 10 CFR 2.390 (Table C-1 only)

TVA BFN Attachment C - NEI 04-02 Table B-3 Fire Area Transition C. NEI 04-02 Table B Fire Area Transition Table C NFPA 805 Ch 4 Compliance (NEI 04-02 Table B-3) 791 Pages Table C NFPA 805 Required Fire Protection Systems and Features 30 Page Page C-1 CNL-14-208, Page E6-15 of 144 BFN Units 1, 2, and 3 NFPA 805 Transition Report, Page 234 of 1661

Attachment C Table C NFPA 805 Required Fire Protection Systems and Features Fire Area ID: 01 Unit 1, RB EL 519'-565', from R1 to a line 10' east of R4 Compliance Basis: NFPA 805 Section 4.2.4.2 Performance-Based Approach - Fire Risk Evaluation with simplifying deterministic assumptions Required Required Suppression Detection Required Fire Fire Zone ID Description System System Protection Feature Required Fire Protection Feature and System Details (All) Area Wide None None R, D Procedures/Recovery Actions:

-- DID: Recovery action(s) required to meet DID criteria.

-- Risk: Recovery action(s) required to meet Risk criteria.

01-01 Unit 1, RB EL 519'-565', from R1 E, R, D, S E, R, D, S E, R, D, S Cable Tray Covers:

to a line 10' east of R4 -- EEEE/LA: LA/Intervening Combustibles Exemption December 17, 2014

-- Risk letter, Enclosure 4, Combustible Loading: PER 965449

-- EEEE/LA: EEEE/FHA Section 4.3; EEEE/MDQ0009992013000151; EEEE/MDQ099920110009 Detection System, smoke detection:

CNL-14-208, Response to NRC Request for Additional Information Regarding the License Amendment Request to Adopt NFPA 805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants for the Browns Ferry Nuclear Pl

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