ML110490165

Summary of Telephone Conference Call with the USNRC and NextEra Energy Seabrook, LLC, to Clarify the Responses to the RAIs Pertaining to the SAMA Review of the Seabrook Station License Renewal Application

ML110490165
Person / Time
Site:	Seabrook
Issue date:	02/28/2011
From:	Michael Wentzel License Renewal Projects Branch 1
To:	NextEra Energy Seabrook
Wentzel, Michael J. NRR/DLR, 415-6459
References
TAC ME3959
Download: ML110490165 (5)

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~o February 28, 2011 LICENSEE:

NextEra Energy Seabrook, LLC FACILITY:

Seabrook Station

SUMMARY

OF TELEPHONE CONFERENCE CALLS HELD ON FEBRUARY 15, 2011, BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND NEXTERA ENERGY SEABROOK, LLC, TO CLARIFY THE RESPONSES TO THE REQUESTS FOR ADDITIONAL INFORMATION PERTAINING TO THE SEVERE ACCIDENT MITIGATION ALTERNATIVES REVIEW OF THE SEABROOK STATION LICENSE RENEWAL APPLICATION (TAC NUMBER ME3959)

The U.S. Nuclear Regulatory Commission (NRC or the staff) and representatives of NextEra Energy Seabrook, LLC (NextEra, or the applicant), held a telephone conference call on February 15, 2011, to discuss and clarify the applicant's responses to the staff's requests for additional information (RAls) concerning the Severe Accident Mitigation Alternatives review of the Seabrook Station, license renewal application (LRA). The telephone conference call was useful in clarifying the intent of the applicant's responses to the staff's RAls and identifying areas where further information was necessary. provides a listing of the participants and Enclosure 2 contains a listing of issues that the staff requested clarification on and that were discussed with the applicant, including a brief description on the status of the items.

The applicant had an opportunity to comment on this summary.

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Michael J. wentz!JrOject Manager Projects Branch 1 Division of License Renewal Office of Nuclear Reactor Regulation Docket No. 50-443

Enclosures:

As stated cc w/encls: Distribution via Listserv

TELEPHONE CONFERENCE CALL SEABROOK STATION LICENSE RENEWAL APPLICATION LIST OF PARTICIPANTS February 15, 2011 PARTICIPANTS AFFILIATIONS Michael Wentzel Ray Gallucci Donnie Harrison Bo Pham Steve Short Bruce Schm idt Garill Coles Richard Cliche Edward Carley Rich Turcotte Paul Willoughby U.S. Nuclear Regulatory Commission (NRC)

NRC NRC NRC Pacific Northwest National Labatory (PNNL)

PNNL PNNL NextEra Energy Seabrook, LLC. (NextEra)

NextEra NextEra NextEra ENCLOSURE 1

TELEPHONE CONFERENCE CALL SEABROOK STATION LICENSE RENEWAL APPLICATION February 15, 2011 The U.S. Nuclear Regulatory Commission (NRC or the staff) and representatives of NextEra Energy Seabrook, LLC (NextEra or the applicant), held a telephone conference call on February 15, 2011, to discuss and clarify the applicant's responses to the staff's requests for additional information (RAls) concerning the Severe Accident Mitigation Alternatives (SAMA) review of the Seabrook Station, license renewal application (LRA). The areas of clarification requested by the staff are discussed below:

1. Response to RAI 1.a. Relative to SAMA #192, provide the change in population dose-risk, and describe NextEra's plans for further consideration of this potentially cost-beneficial SAMA. Clarify why the Upper Bound Cost Benefit is only a factor of 1.4, rather than a factor of 1.9, greater than the Nominal Cost Benefit.

Discussion: The applicant stated that SAMA #192 has been added to Seabrook Station's Long Range Plan to implement this SAMA. The evaluation of this SAMA resulted in a decrease in population dose risk of 6. 14% with the Upper Bound Cost Benefit now assessed at $306.5K, reflecting the uncertainty factor of 1.9 (NextEra indicated that the Upper Bound Cost Benefit in the RAI response reflecting a factor of 1.4 was incorrect).

2. Response to RAI 1.b.1. Provide the fire and seismic core damage frequency (CDF) based on the 2006 probabilistic risk assessment (PRA) model used for the SAMA evaluation.

Discussion: The applicant stated that the fire and seismic COFs for the 2006 PRA model used in the SAMA evaluation is 1. 32E-06 per year and 3. 06E-06 per year, respectively.

3. The responses to RAI 1.f and 2.e state that Tables F.3.1.1.1-2 and F.3.2.1-2 consider initiating events. However, Tables F.3.1.1.1-2 and F.3.2.1-2 show only basic events, and so it is not clear how initiating events are explicitly considered in the importance analysis. For example, the most dominant initiating event contributor according to the listing in Table F.3.1.1.1-1 is loss of station power due to weather (LOSPW), but there appears to be no corresponding event in Tables F3.1.1.1-2 or F3.2.1-2. As an example, demonstrate in Tables F.3.1.1.1-2 and F.3.2.1-2 how LOSPW is considered.

Discussion: The staff will be issuing an additional RAI to address this issue.

4. The responses to RAI 1.f and 2.e also state that Attachment FA describes a number of SAMA PRA cases that specifically addressed initiating events. While this is the case, it is unclear if all of the dominant initiating events in Table F.3.1.1.1-1 are addressed. For example, while Attachment F.A describes uNOLOSP" as the modeling case used to determine the benefit of eliminating all LOSP events, none of the SAMAs evaluated using this case (I.e., SAMAs 13, 14, 16, 24, and 156) specifically addressed initiating event FLLP, "Flood in Turbine Building (causing LOSP)." Other examples from Attachment F.A are PRA cases "FIRE1" and "FIRE2," which are the PRA model cases ENCLOSURE 2

- 2 used to determine the benefit of eliminating control room induced LOCA and fire in Turbine Building causing loss of power to emergency buses, respectively. Neither of these modeling cases addresses the specific scenario of a fire in Switchgear Rooms A or B and no SAMAs were identified or developed to specifically address fire in Switchgear Rooms A and B. In the absence of initiating events in the RRW importance listing, provide a correlation of one or more SAM As to each of the risk significant initiating events (and a justification for any initiating events not addressed by a SAMA).

Discussion: The staff will be issuing an additional RAI to address this issue.

5. Response to RAI 1.e. states that the Seabrook Station PRA Group instructions are consistent with requirements of the American Society of Mechanical Engineers (ASME)

PRA standard, but neither the ASME standard nor its version is referenced.

Environmental Report (ER) Section F.3.3 states that 2005 focused peer review is against the ASME PRA standard, but again the version is not cited, Identify the version of the ASME standard that applies in these two cases.

Discussion: The applicant stated that the 2005 focused scope peer review was performed to the ASME RA-Sa-2003 PRA standard and the Seabrook Station PRA Group instructions are consistent with the requirements ofthe ASMEIANS RA-Sa-2009 PRA standard.

6. The response to RAI 2.a. states that "Therefore, all Level 1 sequences are evaluated by the containment event tree (CET) and it is not necessary to summarize and group similar sequences into Level 1 plant damage states." In light of this response, clarify if the text in the 5th paragraph of ER Section F.3.2.1 about grouping "inputs to the Level 2 analysis" and the benefits of grouping as a way to "focus on the limited number of representative sequences" is erroneous or if is there an explanation for this wording, Discussion: The applicant stated that the cited text in the ER was erroneous and has been clarified in response to RAI 2.a.

7. RAI 2.1 response.

i.

Relative to SAMA #193, provide the change in CDF and change in population dose-risk, and describe NextEra's plans for further consideration of this potentially cost-beneficial SAMA.

Discussion: The applicant stated that SAMA #193 has been added to Seabrook Station's Long Range Plan to be prioritized and considered for further implementation. The evaluation of this SAMA resulted in a decrease in population dose risk of 34. 5% with essentially no change in CDF.

ii.

Relative to basic event #10, page 38 of 116, confirm acronym "BE" means "basic event" or provide its meaning if not.

Discussion: The applicant stated that the acronym "BE" means "basic event. "

- 3

8. Response to RAI 3.b.

i.

Relative to the FIVE fire risk analysis methodology, clarify if fire-induced failures of components or human actions credited for mitigating the initiator are assessed, given that the initiator is now fire-induced (including identifying either new components or actions to be modeled or requantifying the random failure probabilities of previously modeled ones). In addition, clarify if hot shorts are considered and, if so, what probabilities are assigned to these.

ii.

Relative to the fire-induced interfacing system loss-of-coolant accident (ISLOCA)

& Containment Impact section. For the "only area where isolation valves both inside and outside containment could be affected," clarify how "important isolation valves [that] could be controlled locally at the valve" would be so controlled for valves inside containment during operation. For the letdown system and its "several; fail closed air operated valves (AOVs)," clarify the basis for the statement "it is not credible for all three valves to hot short." For "isolation failure of one or more valves of a single train," clarify the statement "the ability to remove power from fail closed valves to provide isolation" and the case for failed open valves due to hot shorting (which could not be de-powered?).

Discussion: The staff will be issuing an additional RAI to address these issues.

9. The response to RAI 3.c.a states that "However, the present PRA model has been updated to the more recent Electric Power Research Institute (EPRI) hazards" and that "This was done because, while the methodology and experts used in developing the EPRI hazard are essentially the same as the Seabrook Station Probabilistic Safety Assessment (SSPSA), the EPRI hazard is more recent and the EPRI uniform hazard spectrum (UHS) developed for the Seabrook Station site is more realistic than that used in the SSP SA." Since the EPRI hazard curve was assessed in the individual plant examination external events (IPEEE) as a sensitivity case, clarify what has changed to conclude that the EPRI hazard curve is more realistic than the SSPSA hazard curve.

Discussion: The staff will be issuing an additional RAI to address this issue.

10. RAI 3.g response. A seismic CDF of 2.2E-05 per year, based on the updated 2008 United States GeologiC Survey (USGS) seismic hazard curves (as determined from GI-199 information), was used to develop a factor of 2.6 multiplier on the maximum attainable benefit (MAB). The revised MAB was used to re-assess only those Phase \\I SAMAs that were qualitatively screened based on high cost or low benefit. Phase II SAMAs that were quantitatively evaluated and determined to not be cost-beneficial in the original analYSis were not re-assessed in the RAI response. Based on a scoping assessment by the NRC staff, applying the 2.6 multiplier to the estimated benefit for these non-reassessed SAMAs will result in many SAM As becoming potentially cost-beneficial, based on the current cost estimates. Provide an assessment of the impact of the higher seismic CDF on all SAMAs, including those identified and evaluated in response to RAls.

Discussion: The staff will be issuing an additional RAI to address this issue.

- 4

11. The response to RAI 5.b states that all top ranked basic events related to large early release frequency (LERF) have been addressed in response to RAI 2.f. This appears to be the case with the exception of basic event FWP161.FS, which has a LERF risk reduction worth (RRW) of 1.0886 (see ER Table F.3.2.1-2). Provide an assessment of this basic event for SAMAs.

Discussion: The staff will be issuing an additional RAI to address this issue.

12. The response to RAI 5.b provides the same disposition (not beneficial based on eliminating all supplemental electric power system (SEPS) failures), same associated SAMAs (#9 and #14), and same two pairs of case studies (PRA cases SEPS for #s 8-9 and OSEP1 for #s 10-11) for basic events #8, #9, #10, and #11, yet the estimated benefits are different between the pairs #s 8-9 and #s 10-11. Clarify the differences in the treatment of these four SAMAs, including the two different case studies.

Discussion: The staff will be issuing an additional RAI to address this issue.

13. In the response to RAI 5.f for Essential Switchgear Rooms, clarify if electrical raceway fire barriers also considered for areas where cables for redundant trains may be co located.

Discussion: The staff will be issuing an additional RAI to address this issue.

14. The results of a Phase II evaluation of SAMA 79 are provided in response to RAI 5.g.

Provide the change in CDF and change in population dose-risk for this SAMA (Case FW01, while as described in ER Appendix F.A, does not appear to have been used for any other SAMA).

Discussion: The applicant stated that the decrease in CDF is 12% and the decrease in population dose-risk is 7.3%.

15. RAI 5.n response. Provide the change in CDF and change in population dose-risk for SAMA 105 (PRA Case OLPRS).

Discussion: The applicant stated that the decrease in CDF is 1.8% and the decrease in population dose-risk is <1 %.

16. RAI 6.a response. The offsite economic cost risk (OECR) reduction is shown to be 9%

for SAMAs 96, 108, and 109, yet the benefit at both 7% discount rate and for the Upper Bound are reported in the ER to be <$1 K. Clarify the basis for the <$1 K benefit given the 9% reduction in OECR.

Discussion: The reduction in OECR reported in the RAI response is incorrect. The actual reduction in OECR is 0%.

17. RAI 6.k response. Clarify why NextEra believes the uncertainty distribution represents the uncertainty in the fire and seismic portions of the PRA model. Include a discussion of whether probability distributions were assigned for external events (such as for fire

- 5 ignition frequencies, non-suppression probabilities, hot short probabilities, seismic frequencies, other seismic parameters} and, if not, how this impacts the SAMA analysis.

Discussion: The staff will be issuing an additional RAI to address this issue.

February 28, 2011 LICENSEE:

NextEra Energy Seabrook, LLC FACILITY:

Seabrook Station

SUMMARY

OF TELEPHONE CONFERENCE CALLS HELD ON FEBRUARY 15, 2011, BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND NEXTERA ENERGY SEABROOK, LLC, TO CLARIFY THE RESPONSES TO THE REQUESTS FOR ADDITIONAL INFORMATION PERTAINING TO THE SEVERE ACCIDENT MITIGATION ALTERNATIVES REVIEW OF THE SEABROOK STATION LICENSE RENEWAL APPLICATION (TAC NUMBER ME3959)

The U.S. Nuclear Regulatory Commission (NRC or the staff) and representatives of NextEra Energy Seabrook, LLC (NextEra, or the applicant), held a telephone conference call on February 15, 2011, to discuss and clarify the applicant's responses to the staff's requests for additional information (RAls) concerning the Severe Accident Mitigation Alternatives review of the Seabrook Station, license renewal application (LRA). The telephone conference call was useful in clarifying the intent of the applicant's responses to the staff's RAls and identifying areas where further information was necessary. provides a listing of the participants and Enclosure 2 contains a Ilsting of issues that the staff requested clarification on and that were discussed with the applicant, including a brief description on the status of the items.

The applicant had an opportunity to comment on this summary.

IRA!

Michael J. Wentzel, Project Manager Projects Branch 1 Division of License Renewal Office of Nuclear Reactor Regulation Docket No. 50-443

Enclosures:

As stated cc w/encls: Distribution via Listserv DISTRIBUTION:

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• concurrence via e-mail OFFICE LA:DLR*

PM:RPB1 :DLR BC: RPB1 :DLR PM:RPB1:DLR NAME YEdmonds MWentzel BPham MWentzel DATE 02/24/2011 02/28/2011 02/27/2011 02/28/2011 OFFICIAL RECORD COpy

Memorandum to NextEra Energy Seabrook, LLC from M. Wentzel dated February 28, 2011

SUMMARY

OF TELEPHONE CONFERENCE CALLS HELD ON FEBRUARY 15, 2011, BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND NEXTERA ENERGY SEABROOK, LLC, TO CLARIFY THE RESPONSES TO THE REQUESTS FOR ADDITIONAL INFORMATION PERTAINING TO THE SEVERE ACCIDENT MITIGATION ALTERNATIVES REVIEW OF THE SEABROOK STATION LICENSE RENEWAL APPLICATION (TAC NUMBER ME3959)

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