ML16252A222

Seabrook Station - Response to RAI Related to Severe Accident Mitigation Alternatives License Renewal Application

ML16252A222
Person / Time
Site:	Seabrook
Issue date:	09/06/2016
From:	McCartney E NextEra Energy Seabrook
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
SBK-L-16134, TAC ME3959
Download: ML16252A222 (9)

Text

. \. U.S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 Seabrook Station NEXTera SEABROOK September 6, 2016 10 CFR 54 SBK-L-16134 Docket No. 50-443 Response to RAI Related to Severe Accident Mitigation Alternatives NextEra Energy Seabrook License Renewal Application References: 1. NextEra Energy Seabrook, LLC letter SBK-L-10077, "Seabrook Station Application for Renewed Operating License," May 25, 2010. (Accession Number ML101590099) 2. NRC Letter, Requests for Additional Information for the Severe Accident Mitigation Alternatives ( S AM A) Review of the Seabrook Station License Renewal Application (TAC No. ME3959), July 8, 2016, (Accession Number ML16187A204) 3. Commissioner Memorandum and Order, CLI-16-07, "In the Matter of Entergy Nuclear Operations, Inc. (Indian Point Nuclear Generating Units 2 and 3)," dated May 4, 2016 (Accession Number ML16125Al50) In Reference 1, NextEra Energy Seabrook, LLC (NextEra) submitted an application for a renewed facility operating license for Seabrook Station Unit 1 in accordance with the Code of Federal Regulations, Title 10, Parts 50, 51, and 54. In Reference 2, the staff requested additional information to support addressing the Commission Memorandum and Order (CLI-16-07) which directed the NRC staff to supplement the SAMA analysis performed for the Indian Point Units 2 and 3 LRA with sensitivity analyses for two factors used in the SAMA analysis (Reference 3). The NextEra Seabrook response to the RAI is provided in the enclosure to this letter. The RAI response includes the results of a sensitivity analysis for the same two input parameters addressed by the Commission in CLI-16-07. The sensitivity analysis demonstrates that the SAMA analysis previously submitted for Seabrook Station remains bounding. NextEra Energy Seabrook, LLC, P.O. Box 300, Lafayette Road, Seabrook, NH 03874

' ' United States Nuclear Regulatory Commission 'SBK-L-16134 I Page 2 No new commitments are being made in this submittal. If there are any questions or additional information is needed, please contact Mr. Edward J Carley, Engineering Supervisor -License Renewal, at (603) 773-7957. If you have any questions regarding this correspondence, please contact Mr. Ken Browne, Licensing Manager, at (603) 773-7932. I declare under penalty of perjury that the foregoing is true and correct. Executed on September ___fo__, 2016 Sincerely, Enclosure: Response to RAI Related to Severe Accident Mitigation Alternatives cc: D. H. Dorman J.C. Poole P. C. Cataldo T. M. Tran L. M. James Mr. Perry Plummer NRC Region I Administrator NRC Project Manager NRC Senior Resident Inspector NRC Project Manager, License Renewal NRC Project Manager, License Renewal Director Homeland Security and Emergency Management New Hampshire Department of Safety Division of Homeland Security and Emergency Management Bureau of Emergency Management 33 Hazen Drive Concord, NH 03305 John Giarrusso, Jr., Nuclear Preparedness Manager The Commonwealth of Massachusetts Emergency Management Agency 400 Worcester Road Framingham, MA 01702-5399

. ,, U.S. Nuclear Regulatory Commission

• SBK-L-16134 /Enclosure I Page 1 Enclosure to SBK-L-16134 NextEra Energy Seabrook Response to RAI Related to Severe Accident Mitigation Alternatives NextEra Energy Seabrook License Renewal Application

. \ U.S. Nuclear Regulatory Commission 'SBK-L-16134 /Enclosure I Page 2 NRC RAI for Licensees regarding CLI-16-07 BACKGROUND: On May 4, 2016, the Commission issued a Memorandum and Order (CLI-16-07) in the Indian Point license renewal proceeding, in which it directed the Staff to supplement the Indian Point Severe Accident Mitigation Alternatives (SAMA) analysis with sensitivity analyses. Specifically, the Commission held that documentation was lacking for two inputs (TIMDEC and CDNFRM) used in the MACCS computer analyses, and that uncertainties in those input values could potentially affect the SAMA analysis cost-benefit conclusions. The Commission therefore directed the Staff to perform additional sensitivity analyses. The two inputs (TIMDEC and CDNFRM), are commonly used in the SAMA analyses performed for license renewal applications (LRAs ). These two input values were generally based on the values provided in NUREG-1150, "Severe Accident Risks: An Assessment for Five U.S. Nuclear Power Plants" and NUREG/CR-3673, "Economic Risks of Nuclear Power Reactor Accidents." The TIMDEC input value defines the time required for completing decontamination to a specified degree. The CDNFRM input parameter defines the cost (on a per person basis) of decontaminating non-farmland by a specified decontamination factor. The CDNFRM values used in NUREG-1150 ($3,000/personfor decontamination factor of 3 and $8,000/person for decontamination factor of 15) stem from decontamination cost estimates provided in NUREG/CR-3673, the same 1984 economic risk study referenced in support of the decontamination time inputs. These decontamination cost inputs are commonly escalated to account for inflation. REQUEST FOR ADDITIONAL INFORMATION: The NRC Staff believes the Commission's decision in CLI-16-07 may be applicable to the SAMA analysis performed for Seabrook Station, Unit 1 (Seabrook), inasmuch as that analysis may have also relied upon the NUREG-1150 values for TIMDEC and CDNFRM. We therefore request that NextEra Energy Seabrook, LLC (NextEra), either justify why CLI-16-07 does not apply to the SAMA analysis performed for Seabrook or supplement the SAMA analysis with sensitivity analyses for the CDNFRM and TIMDEC values. NextEra is requested to review the input values specified_in CLI-16-07 for the Indian Point LRA, and (1) to apply the maximum values specified by the Commission (one year (365 days) for TIMDEC and $100,000 for the CDNFRM values for the decontamination factor of 15) or, in the alternative, (2) to explain, with sufficient justification, its rationale for choosing any other value(s) for its sensitivity analyses. In any event, NextEra should execute sensitivity analyses for the release categories modeled that exceed 1015 Becquerels ofCs-137 released. NextEra is requested to evaluate how these sensitivity analyses may affect its identification of potentially cost-beneficial SAMAs. Finally, upon completing its sensitivity analysis, NextEra is requested to submit the spreadsheet (or equivalent table if another method is used) that conveys the population dose and off-site economic cost for each release category and integrates the results into a Population Dose Risk and an Offsite Economic Cost Risk for Seabrook.

. \. ' U.S. Nuclear Regulatory Commission 'SBK-L-16134 /Enclosure I Page 3 NextEra Seabrook Response Background: As discussed in the RAI, the NRC Commissioners issued a Memorandum and Order (CLI-16-07) in the matter of Entergy Nuclear Operations, Inc. (Indian Point Nuclear Generating Units 2 and 3) on May 4, 2016 (Enclosure Reference 1-1 ). The Commissioners directed the NRC staff to supplement Indian Point's SAMA analysis with a sensitivity analysis using values of 365 days for the TIMDEC input parameter and $100,000/person for heavy decontamination for the CDNFRM input parameter in the MACCS2 (MELCOR Accident Consequence Code) code for at least the four most severe accident categories modeled. The RAI issued to NextEra Energy Seabrook Station requests that Seabrook apply the maximum values specified by the Commission (one year (365 days) for TIMDEC and $100,000/person for the CDNFRM values for the decontamination factor of 15) for the release categories modeled that exceed 1015 Becquerels of Cs-137 released or, in the alternative, explain the rationale for choosing other values for the sensitivity analyses. NextEra Energy has performed a SAMA sensitivity analysis for Seabrook Station using the maximum input parameter values specified by the Commission in CLl-16-07 and by the NRC Staff in the RAI. The results of that analysis are described and summarized below. Decontamination Sensitivity Analysis A sensitivity analysis to determine the Modified Maximum Averted Cost Risk (MMACR) using the highest values allowed in MACCS2 for inputs TIMDEC and CDNFRM, 365 days and $100,000/person, respectively, for the decontamination factor of 15 (heavy decontamination), was performed as specified in CLI-16-07 and in the RAI. All other inputs into the MACCS2 code were unchanged. The evaluation used the higher TIMDEC and CDNFRM input parameter values in the same sensitivity analysis, so that the effects of increasing both values are evaluated concurrently. The RAI indicates that the severe accident categories that exceed 1015 Becquerels of Cs-13 7 released should be considered. Accident releases from Seabrook are modeled via 13 release categories (RC). 10 of the 13 accident release categories exceed the 1015 Becquerels for Cs-137, all of the release categories except SEl, INTACTl and INTACT2. However, as a conservative approach, all of Seabrook's release categories are included in this sensitivity analysis. This includes the following release categories: LEl -Large/Early Cont. Bypass-SG Tube Rupture LE2 -Large/Early Cont. Bypass -ISLOCA LE3 -Large/Early Cont. Penetration Failure to Isolate LE4 -Large Cont. Basemat Failure with Delayed Evacuation SEl -Small/Early Cont. Bypass-SG Tube Rupture w/ Scrubbed Release SE2 -Small/Early Cont. Bypass -ISLOCA w/ Scrubbed Release SE3 -Small/Early Cont. Penetration Failure to Isolate LL3 -Large/Late Cont. Venting LL4 -Large/Late Cont. Overpressure Failure LL5 -Large/Late Cont. Basemat Failure

' . U.S. Nuclear Regulatory Commission 'SBK-L-16134*/Enclosure I Page 4 SELL -Small/Early Cont. Pen. Failure to Isolate & Large/Late Cont. Basemat Failure INTACT! -Nominal Cont. Leakage (mapped to INTACT) INTACT2 -Excessive Cont. Leakage (mapped to INTACT) INTACT-Weighted summation ofINTACTl and INTACT2 After determining the revised population dose and economic costs using the maximum values for CDNFRM and TIMDEC for the above release categories, a Maximum Averted Cost Risk (MACR) was calculated for both the 7% (base) and 3% (sensitivity) discount rates as done in the Seabrook SAMA analysis. In addition, the MACR is increased by a factor of 2.1 to account for the potential risk increase due to seismic hazards. The seismic multiplier was derived and justified as discussed on page 29 of 96 in Enclosure Reference 1-2. The seismic-adjusted MACR is referred to as the "modified" Maximum Averted Cost Risk (MMACR). Note that in the previous Seabrook SAMA documentation, MMACR was referred to as the Maximum Averted (Attainable) Benefit (MAB), which provided the same measure of benefit. The MMACR calculated in this RAI sensitivity analysis is then compared to the 95th percentile MMACR determined in the Seabrook SAMA analysis. The 95th percentile MMACR is obtained by multiplying the MMACR by a factor of2.35 to account for the 95th percentile of the consequence as discussed on page 35of96 in Enclosure Reference 1-2. RAI Sensitivity Results I Comparison Table 1 presents the Level 3 base case results of Public Dose and Economic Risk from the previous Seabrook SAMA evaluation, page 27of96 in Enclosure Reference 1-2. The results of this RAI sensitivity analysis are presented in Tables 2 and 3. Table 2 provides the Population Dose Risk and Economic Cost Risk for each release category. Table 3 compares the Modified Maximum Averted Cost Risk (MMACR) results calculated for both the SAMA base case and the RAI sensitivity case. The results show that the MMACR for the RAI sensitivity case, which used CDNFRM and TIMDEC set to their maximum allowable values for heavy decontamination, is $9,607,670/year for a 7% discount rate. This MMACR is bounded by the 95th percentile of the MMACR in the Seabrook SAMA evaluation which was derived as 2.35 x $6,401,871/year = $15.04M/year. Likewise, the RAI sensitivity analysis MMACR calculated with maximum values for CDNFRM and TIMDEC using a 3% discount rate is $13.67M, which is also bounded by the 95th percentile base case of $15.04M/yr.

. \ U.S. Nuclear Regulatory Commission -SBK-L-16134 /Enclosure I Page 5 Table 1 Seabrook SAMA Base Case Level 3 Results (*) Release Population Economic Frequency Population Economic Category Dose Cost Dose Risk Cost Risk (person REI\ll) ($) (events/yr) (person ($/yr) REM/yr) LE-1 1.26E+07 5.60E+ I 0 5.19E-08 6.54E-OI 2.91E+03 LE-2 4.27E+07 7.14E+l0 l.8 lE-08 7.73E-Ol l.29E+03 LE-3 2.41E+07 6.80E+l0 8.61E-10 2.08E-02 5.85E+Ol LE-4 l.1 lE+07 4.91E+l0 2.11 E-08 2.34E-Ol l .04E+03 SE-1 2.43E+05 3.27£+08 5.08E-07 1.23£-01 l.66E+02 SE-2 8.60E+06 3.09E+IO 2.79£-08 2.40£-01 8.62E+02 SE-3 l.36E+06 2.67£+09 9.97£-07 1.36£+00 2.66E+03 LL-3 3.63E+06 9.05£+09 1.75£-07 6.35£-01 l.58E+03 LL-4 7.27E+06 3.lOE+lO 5.79E-08 4.21E-01 I .79E+03 LL-5 1.03£+07 5.24£+10 3.IOE-06 3.19E+Ol 1.62£+05 SELL l .48E+07 6.53E+10 9.84E-08 l.46E+OO 6.43E+03 INTACT 2.77E+03 2.18£+03 7.14£-06 1.98£-02 l .56E-02 Totals 1.37E+08 4.36E+ll 1.22E-05 3.79E+Ol 1.81E+05 (*) Table 1 is reproduced from table of release category public dose and economic risk results -Level 3 Model provided in letter SBK-L-12053 (Enclosure Reference 1-2), page 27 of96. Table 2 Seabrook SAMA RAI Sensitivity Level 3 Results Release Population Economic Frequency Population Economic Category Dose Cost Dose Risk Cost Risk (person REM) ($) (events/yr) (person ($/yr) REM/yr) LE-1 l.24E+07 l.l!E+ll 5.19£-08 6.44E-01 5.76E+03 LE-2 4.29E+07 1.34E+ 11 1.81E-08 7.76E-01 2.43E+03 LE-3 2.46E+07 l.39E+ 11 8.61E-10 2.12E-02 l.20E+02 LE-4 1.14E+07 9.89E+l0 2. l IE-08 2.4 lE-01 2.09E+03 SE-1 2.47E+05 7.18E+08 5.08E-07 1.25£-01 3.65E+02 SE-2 9.04E+06 6.69E+l0 2.79E-08 2.52E-Ol 1.87£+03 SE-3 l.35E+06 4.01E+09 9.97E-07 l.35E+OO 4.00E+03 LL-3 3.68E+06 J.68E+IO J.75E-07 6.44E-O 1 2.94E+03 LL-4 7.90E+06 6.41E+l0 5.79E-08 4.57E-Ol 3.71E+03 LL-5 9.64E+06 9.40£+10 3.lOE-06 2.99E+Ol 2.9JE+05 SELL 1.47E+07 l .26E+ 11 9.84£-08 1.45£+00 1.24£+04 INTACT 2.77E+03 2.18E+03 7.14£-06 l .98E-02 1.56E-02 Totals 1.38E+08 8.55E+ll 1.22E-05 3.59E+Ol 3.27E+05

.. U.S. Nuclear Regulatory Commission 'SBK-L-16134 /Enclosure I Page 6 Table 3 Seabrook Modified Maximum Averted Cost Risk Results I Comparison Base Case Results RAI Sensitivity Results Description 7% Real 3% Discount 7% Real 3% Discount Discount Rate Rate Sensitivity Discount Rate Rate Sensitivity Averted Public Exposure Cost (APE) $815,072 $1,138,946 $771,886 $1,078,600 Averted Offsite Property Damage Cost $1,950,586 $2,725,665 $3,520,343 $4,919, 175 (AOC) Averted Occupational Exposure Cost (AOE) $4,642 $7,549 $4,642 $7,549 Averted Onsite Cost (AOC) $278,210 $506,062 $278,210 $506,062 Maximum Averted Cost Risk ($/yr) $3,048,510 $4,378,222 $4,575,081 $6,511,386 Seismic Hazard Multiplier 2.10 2.10 2.10 2.10 Modified Maximum Averted Cost Risk $6,401,871 $9,194,265 $9,607,670 $13,673,911 ($/yr) Uncertainty Factor ( 95th Percentile) 2.35 Total MMACR at 95111 Percentile Uncertainty $15.04M Distribution Conclusion: As summarized in Table 3, the sensitivity values for the Modified Maximum Averted Cost Risk (MMACR) are bounded by the previous Seabrook SAMA MMACR, which accounted for the 95th percentile in averted cost risk. Additionally, the maximum increase in benefit of an individual SAMA candidate is bounded by the previous 95th percentile case. The maximum increased value of an individual SAMA candidate could be no greater than the largest ratio of the population dose risk or economic risk of the decontamination sensitivity case to the population dose risk or economic risk in the previous Seabrook SAMA case (Table 1) for all of the modeled release categories. The maximum increase ratio is less than the factor of 2.35 used in Seabrook's SAMA evaluation to judge each individual SAMA candidate against the benefit, which considered the benefit at the 951h percentile. Therefore, the results of the evaluation of potential SAMA candidates previously provided in the SAMA analysis bounds the results of the RAI sensitivity analysis. While the use of the higher RAI decontamination input parameters results in an increase in the MMACR, the RAI sensitivity analysis shows that the results are less than Seabrook's base SAMA MMACR, which considered the MMACR at the 95th percentile. Based on the above, the RAI sensitivity results do not present any new and significant information that could necessitate supplementation of the Final Supplemental Environmental Impact Statement for the Seabrook Station license renewal.

• , ' U.S. Nuclear Regulatory Commission *sBK-L-16134 /Enclosure I Page 7 Enclosure References: 1-1 Commissioner Memorandum and Order, CLI-16-07, "In the Matter of Entergy Nuclear Operations, Inc. (Indian Point Nuclear Generating Units 2 and 3)," dated May 4, 2016 1-2 NextEra Energy Seabrook Station Letter to NRC, "Seabrook Station Supplement 2 to Severe Accident Mitigation Alternatives Analysis" SBK-L-12053, dated March 19, 2012 (Accession Number ML12080Al37)