RS-17-149, Spent Fuel Pool Evaluation Supplemental Report, Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.1 of the Near-Term Task Force Review of Insights from The.

Spent Fuel Pool Evaluation Supplemental Report, Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.1 of the Near-Term Task Force Review of Insights from The.

ML17349A096
Person / Time
Site:	Peach Bottom
Issue date:	12/15/2017
From:	David Helker Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-17-149
Download: ML17349A096 (10)

Text

Exelon Generation 10 CFR 50.54(f)

RS-17-149 December 15, 2017 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555 Peach Bottom Atomic Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-44 and DPR-56 NRC Docket Nos. 50-277 and 50-278

Subject:

Spent Fuel Pool Evaluation Supplemental Report, Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident

References:

1. NRG Letter, Request for Information Pursuant to Title 1O of the Code of Federal Regulations 50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3, of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated March 12, 2012(ML12053A340)

2. NRG Letter, Final Determination of Licensee Seismic Probabilistic Risk Assessments Under the Request for Information Pursuant to Title 1O of the Code of Federal Regulations 50.54(f) Regarding Recommendation 2.1 "Seismic" of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated October 27, 2015, (ML15194A015)

3. NEI Letter, transmits EPRI 3002009564 for NRG endorsement, dated January 31, 2017 (MU 7031A171)

4. EPRI 3002009564, Seismic Evaluation Guidance Spent Fuel Pool Integrity Evaluation, dated January 2017

5. NRG Letter, Endorsement of Electric Power Research Institute Report 3002009564, "Seismic Evaluation Guidance: Spent Fuel Pool Integrity Evaluation", dated February 28, 2017(ML17034A408)

6. Exelon Generation Company, LLC Letter to USNRC, Seismic Hazard and Screening Report (Central and Eastern United States (CEUS) Sites), Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated March 31, 2014 (RS-14-071) (ML14090A247)

U.S. Nuclear Regulatory Commission Seismic Hazard 2.1 Spent Fuel Pool Evaluation December 15, 2017 Page 2

7. NRC Letter to Exelon Generation Company, LLC, Peach Bottom Atomic Power Station, Units 2 and 3, Staff Assessment of Information Provided Pursuant to Title 1O of the Code of Federal Regulations Part 50, Section 50.54(f), Seismic Hazard Reevaluations for Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated April 20, 2015(ML15051A262)

On March 12, 2012, the Nuclear Regulatory Commission (NRG) issued a Request for Information per 10CFR 50.54(f) (Reference 1) to all power reactor licensees. By letter dated October 27, 2015 (Reference 2), the NRC transmitted final seismic information request tables which identified that Peach Bottom Atomic Power Station, Units 2 and 3 is to conduct a limited scope Spent Fuel Pool Evaluation. By Reference 3, Nuclear Energy Institute (NEI) submitted an Electric Power Research Institute (EPRI) report entitled, Seismic Evaluation Guidance Spent Fuel Pool Integrity Evaluation (EPRI 3002009564) (Reference 4) for NRC review and endorsement. NRC endorsement was provided by Reference 5.

EPRI 3002009564 provides criteria for evaluating the seismic adequacy of a spent fuel pool (SFP) to the reevaluated ground motion response spectrum (GMRS) hazard levels. Section 4.3 of EPRI 3002009564 lists the parameters to be verified to confirm that the results of the report are applicable to Peach Bottom Atomic Power Station, Units 2 and 3, and that the Peach Bottom Atomic Power Station, Units 2 and 3 SFP is seismically adequate in accordance with NTTF 2.1 Seismic evaluation criteria.

The attachment to this letter provides the data for Peach Bottom Atomic Power Station, Units 2 and 3 that confirms applicability of the EPRI 3002009564 criteria and confirms that the SFP is seismically adequate in accordance with NTTF 2.1 Seismic evaluation criteria.

This letter closes Regulatory Commitment No. 2 of Reference 6.

This letter contains no new regulatory commitments or revisions to existing regulatory commitments.

If you have any questions regarding this report, please contact David J. Distel at 610-765-5517.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 151n day of December 2017.

Respectfully submitted, David P. Helker Manager - Licensing & Regulatory Affairs Exelon Generation Company, LLC

Attachment:

Site-Specific Spent Fuel Pool Criteria for Peach Bottom Atomic Power Station, Units 2 and 3

U.S. Nuclear Regulatory Commission Seismic Hazard 2.1 Spent Fuel Pool Evaluation December 15, 2017 Page 3 cc: Regional Administrator - NRG Region I NRG Senior Resident Inspector - Peach Bottom Atomic Power Station NRG Project Manager, NRA - Peach Bottom Atomic Power Station Mr. Brett A. Titus, NRR/JLD/JCBB, NRG Mr. Stephen M. Wyman, NRR/JLD/JHMB, NRG Mr. Frankie G. Vega, NRR/JLD/JHMB, NRG Director, Bureau of Radiation Protection - Pennsylvania Department of Environmental Resources S. T. Gray, State of Maryland R. R. Janati, Chief, Division of Nuclear Safety, Pennsylvania Department of Environmental Protection, Bureau of Radiation Protection

ATTACHMENT Site-Specific Spent Fuel Pool Criteria for Peach Bottom Atomic Station, Units 2 and 3

Peach Bottom Atomic Power Station, Units 2 and 3 Seismic Spent Fuel Pool Evaluation Page 1of6 The 10 CFR 50.54(f) letter requested that, in conjunction with the response to Near Term Task Force (NTTF) Recommendation 2.1, a seismic evaluation be performed for the SFP. More specifically, plants were asked to consider "all seismically induced failures that can lead to draining of the SFP ." Such an evaluation would be needed for any plant in which the ground motion response spectrum (GMRS) exceeds the safe shutdown earthquake (SSE) in the 1 to 1O Hz frequency range. The staff confirmed through References A and D that the GMRS exceeds the SSE and concluded that a SFP evaluation is merited for the Peach Bottom Atomic Power Station, Units 2 and 3. By letter dated February 28, 2017 (Reference B) the staff determined that EPRI 3002009564 was an acceptable approach for performing SFP evaluations considering the GMRS hazard levels.

The table below lists the criteria from Sections 4.1 thru 4.3 of EPRI 3002009564 along with data for Peach Bottom Atomic Power Station, Units 2 and 3 that confirms applicability of the EPRI 3002009564 criteria and confirms that the SFP is seismically adequate in accordance with NTTF 2.1 Seismic evaluation criteria.

SFP Criteria from EPRI 3002009564 Site-Specific Data Site Parameters

1. The site-specific GMRS should be The Peach Bottom Atomic Power Station (PBAPS) the same as that submitted to the GMRS used in the SFP evaluation (Reference N)

NRC between March 2014 and July is the GMRS developed for the Peach Bottom 2015, which the NRC has found Seismic Probabilistic Risk Assessment (SPRA).

acceptable for responding to the The SPRA GMRS was developed using the same NRC 50.54(f) letter (Reference D). approach used by EPRI to develop the GMRS that was submitted to the NRC. Additional updated source information and site-specific parameters were used in its development. Note that the GMRS developed by EPRI and submitted to the NRC only provided response spectra in the horizontal direction. For the SPRA, a vertical GMRS was also developed. The resulting vertical in-structure response spectra are used in the SFP evaluation.

The GMRS developed for the SPRA was reviewed as part of the full scope peer review performed for the SPRA. The peak horizontal spectral acceleration from the GMRS developed for the SPRA is approximately 0.65g (Reference 0).

Peach Bottom Atomic Power Station, Units 2 and 3 Seismic Spent Fuel Pool Evaluation Page 2 of 6 Structural Parameters

2. Site-specific calculations, performed Site-specific calculations, performed in accordance in accordance with Section 4.1 of with Section 4.1 of EPRI 3002009564, EPRI 3002009564 should demonstrate that the limiting SFP HCLPF is demonstrate that the limiting SFP 0.827g, which exceeds the GMRS of 0.65g in the High Confidence of Low Probability frequency range of interest (i.e. 10-20 Hz);

of Failure (HCLPF) is greater than therefore, this criterion is met for Peach Bottom the site-specific GMRS in the Atomic Power Station.

frequency range of interest (e.g., 10- It should be noted that peak broadening was not 20 Hz). used in the PBAPS analysis as used in Section C.3.7 of EPRI 3002009564. The controlling failure mode for the SFP is an out-of-plane shear (diagonal tension) crack of the floor slab, which occurs suddenly. Prior to the formation of the shear crack, there is minimal cracking due to flexure. The panel frequency was calculated using 50% of the un-cracked stiffness, consistent with EPRI Report 3002009564. Therefore, for the controlling failure mode, the frequency calculated is considered a lower bound. Note, given the shape of the in-structure response spectra based on the Peach Bottom GMRS, the lower the frequency, the higher the demand in terms of seismic acceleration.

The reason for the further broadening in the EPRI report (Reference P) is to account for uncertainty in the building and soil properties. For PBAPS, there is no variation in the soil properties because the Reactor Building is founded on solid rock. Lower bound structural properties are already considered in the evaluation by use of 50% of the un-cracked stiffness. This was coupled with a conservative damping of 4%. Note that if the stiffness is reduced further, the model becomes equivalent to that of a cracked model. In this case, the damping would increase and the natural frequency of the structure would decrease. The net result would be an overall reduction in the in-structure response spectra.

Given the approach used, the controlling failure mode and conservative assumptions regarding damping for generating in-structure response spectra, there is no reason to further lower the calculated frequency of the SFP slab. Therefore, this approach is considered to be consistent with the intent of the EPRI report.

Peach Bottom Atomic Power Station, Units 2 and 3 Seismic Spent Fuel Pool Evaluation Page 3 of 6

3. The SFP structure should be The SFP structure is included in the PBAPS Civil included in the Civil Inspection Inspection Program in accordance with 10 CFR Program performed in accordance 50.65 (Reference E); therefore, this criterion is met with Maintenance Rule. for PBAPS.

Non-Structural Parameters

4. To confirm applicability of the piping As documented in site Drawings M-87 and M-156 evaluation in Section 4.2 of EPRI (References F and G), the SFP piping penetrations 3002009564, piping attached to the occur at a depth not greater than 6 ft below the SFP should have penetrations no normal water level. Therefore, this criterion is met more than 6 ft below water surface. for PBAPS.

5. To confirm ductile behavior under The SFP gate is mainly constructed from aluminum increased seismic demands, SFP with some stainless steel parts as documented in gates should be constructed from Drawing M-1-M-61 (Reference L); therefore, this either aluminum or stainless steel criterion is met for PBAPS.

alloys.

6. Anti-siphoning devices should be Per Note 3 of Drawings M-363 Sheets 1 and 2 installed on any piping that could (References H and I), siphon breaker holes are lead to siphoning water from the provided on each of the lines that penetrate the SFP. In addition, for any cases SFP to prevent drain-down of the pools.

where active anti-siphoning devices Additionally, check valves are provided on all lines are attached to 2-inch or smaller penetrating the pool to prevent drain-down. As piping and have extremely large described, anti-siphoning devices are installed on extended operators, the valves all lines penetrating the pool to prevent siphoning.

should be walked down to confirm Therefore, this criterion is met for PBAPS.

adequate lateral support. No active anti-siphoning devices attached to 2-inch or smaller piping are present. Therefore, this criterion is met for PBAPS.

7. To confirm applicability of the The PBAPS SFP has a maximum length/width sloshing evaluation in Section 4.2 of dimension of 40 ft and a depth of approximately EPRI 3002009564, the maximum 38' - 9" based on Drawing S-139 (Reference K);

SFP horizontal dimension (length or therefore, this criterion is met for PBAPS.

width) should be less than 125 ft and the SFP depth should be greater than 36 ft.

Peach Bottom Atomic Power Station, Units 2 and 3 Seismic Spent Fuel Pool Evaluation Page 4 of 6

8. To confirm applicability of the The PBAPS SFP has a surface area of evaporation loss evaluation in approximately 1,413 ft 2 , which is greater than Section 4.2 of EPRI 3002009564, 500 ft2

• the SFP surface area should be greater than 500 ft2 and the licensed The licensed reactor core thermal power for each reactor core thermal power should unit is 4,016 MW, (Reference M). This is 0.4%

be less than 4,000 MW, per unit. greater than the maximum thermal power of 4,000 MW, specified in EPRI 3002009564. This slight exceedance is judged to not have a significant impact on the plant-specific evaluations and results described in EPRI 3002009564.

Appendix B to EPRI 30020099564 describes the approach for estimating site-specific boil off times.

It is noted that 4,000 MW, maximum thermal core power represents the upper range of several plants that were surveyed for representative heat loads and outage periods, rather than a limit on the applicability of the Appendix B methodology. It is also noted that the sloshing losses, which are used as input to the boil-off calculation, are based on conservative assumptions, as described in Section 3.2.3 of EPRI 3002009564. This report section describes that sloshing losses, computed in accordance with the SPID (Reference Q), are 4-5 times more than those experienced in actual seismic events. On this basis, the conservative sloshing amplitudes are judged to be an additional source of margin in the boil-off calculations.

Another source of margin in the boil-off results are the site-specific results shown in Figure 4-3 of EPRI 3002009564. This plot indicates that for the two BWR cases, there is at least 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> beyond the required 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> (for uncovering upper 1/3 height of fuel assemblies). On this basis, the slight exceedance (0.4%) of reactor core thermal power is not considered to be significant.

However, to confirm this assumption, a sensitivity study was performed using the sample SFP heat up and boil-off calculation in EPRI 3002009564, Appendix B. The SFP dimensions used in this calculation are similar to the dimensions of the PBAPS SFP and are therefore appropriate to be used for a sensitivity. Re-performing the sample calculation using a licensed reactor core power of 4,000 MWt provides an estimated time to boil-off to upper 1/3 of fuel assembly height (Tupper-third) of 234.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. Using the 84% envelope in figure B-2 of EPRI 3002009564, a heat load of 3.598 MW can

Peach Bottom Atomic Power Station, Units 2 and 3 Seismic Spent Fuel Pool Evaluation Page 5 of 6 be extrapolated for a power level of 4,016 MW,.

This heat load provides a Tupper-third of 234.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />.

This 0.6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> difference helps to confirm that the 16 MW, overrun has a negligible impact on the time before uncover of spent fuel relative to the allowable 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> (<1%).

Additionally, the most recent PBAPS uprate which increased the licensed thermal power from 3,951 MW, to 4,016 MW, was a measurement uncertainty uprate. Since this uprate took advantage of existing power measurement uncertainty, the heat load used in the stations SFP time to boil analysis remains unchanged. Therefore, any heat load information potentially used by EPRI from PBAPS in development of EPRI 3002009564 would have remained unchanged from before the power uprate.

Considering the negligible exceedance of the 4,000 MW1 limit, the small impact it has on time to spent fuel uncover, and the basis for the most recent uprate, the intent of this criterion is met for PBAPS.

Attachment

References:

A. NRG Letter, Final Determination of Licensee Seismic Probabilistic Risk Assessments Under the Request for Information Pursuant to Title 1O of the Code of Federal Regulations 50.54(f) Regarding Recommendation 2.1 "Seismic" of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated October 27, 2015 (ML15194A015)

B. NRG Letter, Endorsement of Electric Power Research Institute Report 3002009564, "Seismic Evaluation Guidance: Spent Fuel Pool Integrity Evaluation", dated February 28, 2017 (ML17034A408)

C. Exelon Generation Company, LLC Letter to USNRC, Seismic Hazard and Screening Report (Central and Eastern United States (CEUS) Sites), Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated March 31, 2014 (RS-14-071) (ML14090A247)

D. NRC Letter to Exelon Generation Company, LLC, Peach Bottom Atomic Power Station, Units 2 and 3, Staff Assessment of Information Provided Pursuant to Title 1O of the Code of Federal Regulations Part 50, Section 50.54(f), Seismic Hazard Reevaluations for Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated April 20, 2015(ML15051A262)

Peach Bottom Atomic Power Station, Units 2 and 3 Seismic Spent Fuel Pool Evaluation Page 6 of 6 E. Procedure ER-PB-450-1006, Rev. 4, "Peach Bottom Structures Monitoring Instructions" F. Drawing M-87, Rev. 17, Piping and Mechanical Reactor Building Unit No. 2 Plan at El.

195' -0" Area 7 G. Drawing M-156, Rev. 12, Piping and Mechanical Reactor Building Unit No. 3 Plan at El.

195' -0" Area 15 H. Drawing M-363 Sheet 1, Rev. 43, Unit 2 P&I Diagram Fuel Pool Cooling & Clean-up I. Drawing M-363 Sheet 2, Rev. 44, Unit 3 P&I Diagram Fuel Pool Cooling & Clean-up J. Drawing S-211, Rev. 3, Reactor Building - Unit #2 Spent Fuel & Dryer Separator Pools Plan K. Drawing S-139, Rev. 5, Reactor Building Area 7&8 Interior Wall Elevations 195' - O" to 234' -0" L. Drawing M-1-M-61, Rev. 1, Fuel Pool Gate Fuel Storage, Refueling System M. NRC Letter to Exelon Generation Company, LLC, Peach Bottom Atomic Power Station, Units 2 and 3 - Issuance of Amendments Re: Measurement Uncertainty Recapture Power Uprate (CAC Nos. MF9289 and MF9290; EPID L-2017-LLS-0001 ), dated November15,2017(ML17286A01~

N. Peach Bottom Analysis No. PS-1175, Rev. O, "Spent Fuel Pool Integrity Evaluation"

0. Probabilistic Seismic Hazards Analysis for Peach Bottom Atomic Power Station PSHA Results Report, FUGRO CONSULTANTS, INC. PROJECT REPORT, dated September 5, 2017 P. EPRI 3002009564, Seismic Evaluation Guidance Spent Fuel Pool Integrity Evaluation, dated January 2017 Q. EPRI 1025287, Seismic Evaluation Guidance Screening, Prioritization and Implementation Details (SPID) for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic, dated February 2013