ML14083A377
| ML14083A377 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 07/14/2014 |
| From: | Audrey Klett Plant Licensing Branch II |
| To: | Nazar M Nextera Energy |
| Klett A DORL/LPL2-1 301-415-0489 | |
| References | |
| TAC ME8991, TAC MF8990 | |
| Download: ML14083A377 (5) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. Mano Nazar President and Chief Nuclear Officer Nuclear Division NextEra Energy P. 0. Box 14000 700 Universe Boulevard Juno Beach, FL 33408-0420 July 14, 2014
SUBJECT:
TURKEY POINT NUCLEAR GENERATING UNIT NOS. 3 AND 4-REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST TO ADOPT NATIONAL FIRE PROTECTION ASSOCIATION STANDARD 805 PERFORMANCE-BASED STANDARD FOR FIRE PROTECTION (TAC NOS. ME8990 AND ME8991)
Dear Mr. Nazar:
By letter dated June 28, 2012, as supplemented by letters dated September 19, 2012, March 18, April16, and May 15, 2013, and January 7, April4, and June 6, 2014, Florida Power & Light Company (the licensee) submitted a license amendment request for the Turkey Point Nuclear Generating Unit Nos. 3 and 4 (Turkey Point 3 and 4). The proposed amendment requested approval to transition the fire protection licensing basis from Title 10 of the Code of Federal Regulations (1 0 CFR), Section 50.48(b) to 10 CFR 50.48(c), National Fire Protection Association Standard 805, Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants.
The U.S. Nuclear Regulatory Commission (NRC) staff reviewed the information provided by the licensee and participated in an audit at Turkey Point 3 and 4 the week of December 10, 2012. By correspondence dated September 11, 2012, March 15, and November 7, 2013, and February 10, and May 27, 2014, the NRC staff requested additional information. By letters dated September 19, 2012, March 18, April16, and May 15, 2013, and January 7, April4, and June 6, 2014, the licensee responded to those requests. The NRC staff determined that it needs additional information regarding the licensee's probabilistic risk assessment (PRA) to complete the review. The enclosure to this letter contains the NRC staff's request for additional information (RAI). As previously discussed with Ms. Olga Hanek of the licensee's staff on July 10, 2014, the NRC is requesting responses to the RAI as follows:
Responses due July 31, 2014: RAis and portions of RAis that involve clarifications of the licensee's PRA methodology (i.e., PRA RAis 01.j.01.01, 01.k.01, 01.r.02.c.01, 01.t.01.01, 07.01.c.01, 11.01.c.01, 13.01.c.01, 18.01.01, and 29.b.01), and Responses due August 15, 2014: RAis and portions of RAis that request quantitative results (i.e., PRA RAis 01.k.01, 07.01.c.01, 11.01.c.01, 13.01.c.01 and 29.c).
If you have any questions, please contact me at (301) 415-0489.
Docket Nos. 50-250 and 50-251
Enclosure:
Request for Additional Information cc w/encl.: Distribution via Listserv Sincerely, Audrey L. Klett, Project Manager Plant Licensing Branch 11-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST TO ADOPT NATIONAL FIRE PROTECTION ASSOCIATION STANDARD 805 PERFORMANCE-BASED STANDARD FOR FIRE PROTECTION FOR LIGHT WATER REACTOR ELECTRIC GENERATING PLANTS FLORIDA POWER & LIGHT COMPANY TURKEY POINT NUCLEAR GENERATION UNIT NOS. 3 AND 4 DOCKET NOS. 50-250 AND 50-251 BACKGROUND By letter dated June 28, 2012 (Agencywide Documents and Management System (ADAMS)
Accession No. ML12191A048), as supplemented by letters dated September 19, 2012, March 18, April16, and May 15, 2013, and January 7, April4, and June 6, 2014 (ADAMS Accession Nos. ML12278A106, ML13099A441, ML13109A008, ML13157A011, and ML14030A114, ML14113A176, and ML14177A650 respectively), Florida Power & Light Company (the licensee) submitted a license amendment request (LAR) for the Turkey Point Nuclear Generating Unit Nos. 3 and 4 (Turkey Point 3 and 4). The proposed amendment requested approval to transition the fire protection licensing basis from Title 10 of the Code of Federal Regulations (10 CFR),
Section 50.48(b) to 10 CFR 50.48(c), National Fire Protection Association Standard 805 (NFPA-805), Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants.
The U.S. Nuclear Regulatory Commission (NRC) staff reviewed the information provided by the licensee and participated in an audit at Turkey Point 3 and 4 the week of December 10, 2012. By correspondence dated September 11, 2012, March 15, and November 7, 2013, and February 10, and May 27, 2014 (ADAMS Accession Nos. ML12256A935, ML13038A310, ML13312A230, ML14016A064, and ML14132A081, respectively), the NRC staff requested additional information.
By letters dated September 19, 2012, March 18, April16, and May 15, 2013, and January 7, April4, and June 6, 2014, the licensee responded to those requests. The NRC staff determined that it needs the following additional information to complete its review.
REQUEST FOR ADDITIONAL INFORMATION Probabilistic Risk Assessment (PRA) RAI 01.j.01.01 The response to PRA 01.j.01 identified several fire-specific parameters for which Monte Carlo uncertainty has been performed to generate mean values that include state-of-knowledge-correlations. The response reported that the mean values are no more than 1 percent higher than the point estimates. A 1 percent difference of a total core damage frequencr (CDF) of abo~~ 5 x 1 o-5/year is a negligible val_u_e compared to the CDF guideline of 1 x 1 o- /year for trans1t1on. The entry for PRA RAI 01.J 1n the Table on page 94 of 101 under Enclosure "Post Transition PRA Disposition" in the response dated April 4, 1014, states that the "Point value will continue to be used based on the point value being consistent with the mean value." A one percent difference of a total CDF of about 5 x 1 o-5/year is about 5 x 1 o-7/year, which is five times greater than the self-approval CDF guideline after transition. If mean values will not be generated post-transition, clarify in the "Post Transition PRA Disposition" how the results of the post-transition fire risk evaluations will be verified to be close enough to the mean that they can distinguish between lying above or below the self-approval mean value guidelines.
PRA RAI 01.k.01 In the April 4, 2014, RAI response to PRA RAI 29a, the entry for PRA RAI 01.k in the Table on page 92 of 101, under "Post Transition PRA Disposition," states that "[c]redit for joint HEPs [human error probabilities] below 1 OE-05 will be retained with adequate justification per the PRA Standard." NUREG-1921 indicates, and NUREG-1792 (Table 2-1) states that joint HEP values should not be below 1 o-5. Electric Power Research Institute (EPRI) Table 4-3 provides a lower limiting value of 1 o-6 for sequences with a very low level of dependence.
Alternatively, the NRC staff has accepted general use of a 1 o-5 floor value for fire specific joint HEPs and 1 o-6 floor value for joint HEPs from the internal events that are credited in the fire PRA without additional justification for individual HEPs.
- i.
Confirm that each HEP value used to support the LAR below 1 o-5 includes its own justification that demonstrates the inapplicability of the NUREG-1792 lower value guideline. Provide an estimate of the number of joint HEPs between 1 o-5 and 1 o-6 and at least two different examples of the justification.
ii.
Confirm that each HEP value below 1 o-6 further includes its own justification that demonstrates that all the individual actions are independent. Provide an estimate of the number of HEPs less than 10-6 and at least two different examples of the justification.
iii.
Clarify in the "Post Transition PRA Disposition" how joint HEPs will be retained.
PRA RAI 01.r.02.c.01 The April 4, 2014, response to RAI PRA 01.r.02.c states that "scenarios have been created for the back panels in which adjacent panels are assumed to be impacted from fire propagation." Briefly summarize how the method to consider propagation of fire beyond the ignition source cabinets in the back panels of the main control room aligns with the approach recommended in Appendix S of NUREG/CR-6850. If the approach differs, provide justification for its use.
PRA RAI 01.t.01.01 In the April 4, 2014, response to PRA RAI 29 the entry for RAI 01.t.01 in the Table on page 95 of 101 under "Final Composite Analysis Disposition" states that the Fire PRA "[e]liminated panel factors and incorporated use of NUREG/CR-6850, Appendix H." However, this disposition does not fully characterize the modeling changes addressed by the response to PRA RAI 01.t.01 (e.g.,
those associated with the damage accrual function and its treatment of the preheating of targets, treatment of dependencies between manual non-suppression probabilities, the reliability and unavailability of credited automatic detection and suppression systems, etc.). Clarify in the "Final Composite Analysis Disposition" that the fire PRA used to support the final composite analysis and post-transition will be updated to incorporate the analysis and modeling changes described in the response to PRA RAI 01.t.01.
PRA RAI 07.01.c.01 The April4, 2014, response to PRA RAI 07.01.c states that "panels of 440 V [volts] or greater[... ]
are not assumed to propagate a fire outside[... ] consistent with the guidance of NUREG/CR-6850
[... ]." Associated guidance in Frequently Asked Question 08-0042 from Supplement 1 of NUREG/CR-6850 applies to electrical cabinets below 440 V. With respect to Bin 15 as discussed in Chapter 6, it clarifies the meaning of "robustly-or well-sealed" when used in conjunction with these lower voltage cabinets. For those cabinets of 440 V and higher, the original guidance in Chapter 6 remains: "Also note that panels that house circuit voltages of 440 V or greater are counted because an arcing fault could compromise panel integrity (an arcing fault could burn through the panel sides, but this should not be confused with the high energy arcing fault type fires)." Therefore, propagation of fire outside the ignition source panel must be evaluated for Bin 15 panels that house circuits of 440 volts or greater. Clarify whether the fire PRA used to support the final composite analysis and post-transition will be updated to incorporate the analysis and modeling changes described in the response to PRA RAI 07.01, but also including an evaluation about fire propagation outside of Bin 15 panels that house circuits of 440 V or greater in accordance with accepted guidance as summarized above.
PRA RAI 11.01.c.01 The April4, 2014, response to RAI PRA 11.01.c did not provide the requested frequencies for the fire-induced main control room (MCR) abandonment scenarios. The results of the delta-risk evaluation for MCR abandonment documented in the license amendment request and experience from other NFPA-805 reviews indicate that the assumption about the probability of failing to successfully shut down after MCR abandonment is a key assumption that can directly impact the regulatory decision. To support resolution of this key assumption, provide the requested MCR abandonment frequency for the compliant case, and for each of the three variant case bins developed from the final composite analysis.
PRA RAI 13.01.c.01 The April4, 2014, response to PRA RA113.01.c states that the methods used for evaluating delta (.~) CDF and ~LERF "provide a conservative bounding analysis of the delta risk." An overestimate of the compliant plant risk, unless offset with a similar overestimate-in the variant plant risk, results in a non-conservative analysis of the delta risk. The method applied to the cable spreading room described in the response to RAI13.01.a and summarized below applies different assumptions to the variant and the complaint plant risk estimates with an indeterminate but most likely nonconservative impact on the change in risk estimate.
The March 18, 2013, response to PRA RAI 13 states that "[t]here are no outside control room fires which result in the loss of sufficient control room control capabilities to warrant control room abandonment. For a control room fire, control room abandonment results from habitability (temperature and visual impact of the fire)." The response to PRA RAI 13 discusses cable spreading room fires and states that following fires in this area, the plant will be shut down using the MCR and assisted by primary control station actions as needed. Nevertheless, PRA RAI 13.01 states that cable-spreading room fire "scenarios with variant-case CCDP [conditional core damage probability]>0.056 (... )used 0.056 as the compliant case CCDP." The 0.056 value was developed to characterize the failure to shut down using only a single, least reliable train and after MCR abandonment. This approach sets the variance from deterministic requirements (VFDR) delta risk to zero for all scenarios having a variant-case CCDP less than 0.056. Hence, this approach, and any similar approach that essentially sets to zero the delta risk for scenarios impacting VFDRs (e.g., assuming such impact only for hot gas layer scenarios}, is non-conservative for the delta risk. There appears to be no reason to use worst case MCR abandonment CCDP for every fire in the cable spreading room that doesn't always fail all equipment but the least reliable train, and that doesn't require the operator to abandon the MCR.
In general, compliant case CCDPs for the cable room fires should be smaller than the worst case MCR abandonment CCDP. Apparently the variant case CCDP has been estimated (to know whether it is greater than 0.056), and the accepted method of removing variations from deterministic requirement failures from the variant case models to represent the compliant plant could be applied. An alternative is to not credit MCR abandonment due to loss of control and resolve VFDRs in the compliant case (e.g., set associated recovery actions in the variant case to successful). Provide a change in risk estimate that is not indeterminately nonconservative.
PRA RAI 18.01.01 The April4, 2014, response to PRA RAI 18.01 states that a review of transient controls during the period between November 2009 and April 2012 revealed violations "primarily related to outage activities," which implies that at least some violations were identified during power operations or low-power operations, such as plant start-up. In accordance with the memorandum dated June 21, 2012 (ADAMS Accession No. ML12171A583), from Joseph Giitter to Biff Bradley, titled, "Recent Fire PRA Methods Review Panel Decisions and EPRI 1022993, 'Evaluation of Peak Heat Release Rates in Electrical Cabinets Fires,"' characterize these violations, considering whether (1) they impact the transient fire heat release rate determination and (2) whether they reflect isolated incidents or a more general pattern of violations.
PRA RAI 29.b.01 The April4, 2014, response to RAI PRA 29.b indicates that a FlowServe reactor coolant pump (RCP) seal PRA model (logic structure and basic event values) has been developed for the FlowServe RCP seal package that will be installed. The response states that an implementation item will be added to LAR AttachmentS, Table S-2, "that will include confirmation of the above logic against the NRC approved FlowServe Topical Report."
- i.
Confirm whether the referenced "NRC approved" report is, "Model for Failure of RCP Seals Given Loss of Seal Cooling in CE NSSS [Combustion Engineering Nuclear Steam Supply System] Plants," WCAP-16175-P-A, Rev 0, March 2007 (ADAMS Accession No. ML071130391 ). If this is not the report that is used, please clarify.
ii.
Provide technical design and testing evaluations that support the Turkey Point PRA model.
iii.
Summarize the differences and similarities between the FlowServe RCP PRA model in the Turkey Point PRA and the PRA models in WCAP-16175-P-A. Separately discuss the logic model and the basic events values if possible.
iv.
Summarize whether any testing will be required to confirm the projected reliability of the seals and how such testing is reflected in the FlowServe RCP PRA model.
- v.
Provide an additional Table S-3 implementation item that will specifically identify when a confirmatory evaluation of the achieved NFPA-805 transition change in risk that includes the installed and tested seals will be completed, what change in risk guidance will be used to determine any required action, and what that action will be required to replace or compliment the new implementation item 18 on page 100 of 101 in the RAI response.
PRA RAI29.c By letter dated February 10, 2014, in PRA RAI 29.a, the NRC staff requested the licensee to indicate how it will address the use of unacceptable methods identified in previous RAI responses in its final composite analysis results. By letter dated April4, 2014, the licensee responded to this RAI. The response to RAI 29.a in "Attachment to L-2014-071" included a Table (i.e., the Table) on pages 92 to 96. The Table included one column labeled, "Issue," one labeled, "Final composite Analysis Disposition," and one labeled, "Post Transition PRA Disposition." The "Issue" column referenced the RAI number that raised the issue.
In this RAIIetter, the NRC staff is requesting additional information about seven of the RAI responses in the Table. The NRC staff is also requesting in this RAIIetter additional information related to the April 4, 2014, responses to RAis 18.01 and 29.b that were not included in the Table.
- i.
By August 15, 2014, please update and provide the Table to address the proposed resolution of the RAis requested in this letter.
ii.
By August 15, 2014, provide final risk estimates (i.e., the CDF, LERF, ~CDF, and ~LERF, and additional risk of recovery actions) based on a PRA that uses only acceptable methods as summarized in the response to RAI 29.c.i for any method that affects the transition change in risk estimates. Discuss the likelihood that the risk increase in any individual fire area would exceed the acceptance guidelines and, if so, why exceeding the guidelines should be acceptable.
ML14083A377 OFFICE LPLII-2/PM LPLII-2/LA NRR/APLA!BC*
NAME AKiett BCiayton HHamzehee (SDinsmore fad DATE 07/14/14 06/07/14 07/14/14 RidsAcrsAcnw_MaiiCTR RidsNrrDraAfpb BMiller, NRR SWall, NRR
- by email LPLII-2/BC (A)
LPLII-2/PM LRegner AKiett 07/14/14 07/14/14