ML18003B419
| ML18003B419 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 01/23/2018 |
| From: | Brett Titus Beyond-Design-Basis Management Branch |
| To: | Diya F Union Electric Co |
| Titus B | |
| References | |
| EPID L-2017-JLD-0042 | |
| Download: ML18003B419 (14) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 January 23, 2018 Mr. Fadi Diya Senior Vice President and Chief Nuclear Officer Ameren Missouri Callaway Plant P.O. Box 620 Fulton, MO 65251
SUBJECT:
CALLAWAY PLANT, UNIT 1 - STAFF REVIEW OF SPENT FUEL POOL EVALUATION ASSOCIATED WITH REEVALUATED SEISMIC HAZARD IMPLEMENTING NEAR-TERM TASK FORCE RECOMMENDATION 2.1:
SEISMIC (EPID L-2017-JLD-0042)
Dear Mr. Diya:
The purpose of this letter is to inform Union Electric Company, doing business as Ameren Missouri (the licensee), of the results of the U.S. Nuclear Regulatory Commission (NRC) staff's review of the spent fuel pool (SFP) evaluation for Callaway Plant, Unit 1 (Callaway), which was submitted in response to Item 9 of Enclosure 1 of the NRC's March 12, 2012, request for information (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12053A340) issued under Title 10 of the Code of Federal Regulations Part 50, Section 50.54(f) (hereafter referred to as the 50.54(f) letter). The NRC staff concludes that the licensee's assessment was performed consistent with the NRG-endorsed SFP Evaluation Guidance Report and that the licensee has provided sufficient information to complete the response to Item 9 of the 50.54(f) letter.
BACKGROUND On March 12, 2012, the NRC issued a 50.54(f) letter as part of implementing lessons learned from the accident at the Fukushima Dai-ichi nuclear power plant. Enclosure 1 to the 50.54(f) letter requested that licensees reevaluate seismic hazards at their sites using present-day methodologies and guidance. Enclosure 1, Item 4, of the 50.54(f) letter requested that licensees perform a comparison of the ground motion response spectrum (GMRS) and the safe shutdown earthquake (SSE). The staff's assessment of the information provided in response to Items 1-3 and 5-7 and the comparison portion of Item (4) of the 50.54(f) letter was provided by letter dated April 21, 2015 (ADAMS Accession No. ML15063A517). Enclosure 1, Item 9, of the 50.54(f) letter requested that, when the GMRS exceeds the SSE in the 1 to 10 Hertz frequency range, a seismic evaluation be made of the SFP. More specifically, plants were asked to consider " ... all seismically induced failures that can lead to draining of the SFP."
F. Diya By letter dated January 31, 2017 (ADAMS Accession No. ML17031A171), the Nuclear Energy Institute (NEI) staff submitted Electric Power Research Institute (EPRI) Report No. 3002009564 entitled, "Seismic Evaluation Guidance: Spent Fuel Pool Integrity Evaluation" (SFP Evaluation Guidance Report). The SFP Evaluation Guidance Report provides criteria for evaluating the seismic adequacy of an SFP to the reevaluated GMRS hazard levels. This report supplements the guidance in EPRI Report 1025287, "Seismic Evaluation Guidance: Screening, Prioritization and Implementation Details (SPID)" (ADAMS Accession No. ML12333A170). The NRC endorsed the SFP Evaluation Guidance Report by letter dated February 28, 2017 (ADAMS Accession No. ML17034A408), as an acceptable method for licensees to use when responding to Item 9 in Enclosure 1 of the 50.54(f) letter.
By letter dated October 27, 2015 (ADAMS Accession No. ML15194A015), the NRC staff stated that SFP evaluation submittals for sites with GMRS peak spectral accelerations above 0.8g are expected by December 31, 2017.
By letter dated July 6, 2017 (ADAMS Accession No. ML17177A446), the NRC issued a generic audit plan and entered into the audit process described in Office Instruction LIC-111, "Regulatory Audits", dated December 29, 2008 (ADAMS Accession No. ML082900195), to assist in the timely and efficient closure of activities associated with the 10 CFR 50.54(f) letter.
The Callaway site was included in the list of applicable licensees. The staff exercised the audit process as described below during the SFP evaluation review.
REVIEW OF LICENSEE SPENT FUEL POOL EVALUATION By letter dated October 3, 2017 (ADAMS Accession No. ML172768201 ), the licensee submitted its SFP evaluation for Callaway. The NRC staff assessed the licensee's implementation of the SFP Evaluation Guidance Report through the completion of a reviewer checklist, which is included as an enclosure to this letter.
TECHNICAL EVALUATION Section 4.0 of the SFP Evaluation Guidance Report develops SFP evaluation criteria for plants with GMRS peak spectral acceleration greater than 0.8g. These criteria address SFP structural elements (e.g., floors, walls, and supports); non-structural elements (e.g., penetrations);
seismically-induced SFP sloshing; and water losses due to heat-up and boil-off. Section 4.0 also provides applicability criteria, that enables licensees to determine if their site-specific conditions are within the bounds considered in developing some of the evaluation criteria in the guidance report. In its review, the staff confirms that the SFP Evaluation Guidance Report methodology has been followed when calculating the site-specific seismic capacity of the SFP, and that Callaway's site-specific values and conditions are within the acceptable limits and bounds considered for the non-structural evaluation criteria specified in the SFP Evaluation Guidance Report.
SPENT FUEL POOL STRUCTURAL EVALUATION Section 4.1 of the SFP Evaluation Guidance Report provides a SFP structural evaluation approach used to demonstrate that the SFP structure is sufficiently robust against the reevaluated seismic hazard. This approach supplements the guidance in Section 7 of the SPID and follows acceptable methods used to assess the seismic capacity of structures, systems, and components (SSCs) for nuclear power plants. In short, Sections 4.1.1 and 4.1.2 describe an acceptable method for licensees to use to calculate a site-specific seismic high confidence of
F. Diya low probability of failure (HCLPF) value for the SFP that is then compared to the site-specific GMRS.
The licensee stated that it followed the SFP structural evaluation approach presented in the SFP Evaluation Guidance Report and, as a part of the audit process, provided site-specific data to the NRC staff to confirm the stated results for Callaway.
As a part of the audit process, the NRC staff reviewed the information provided in calculation AMN-12-CALC-001, Rev. 0, and confirmed that the site-specific HCLPF value calculated for Callaway's SFP followed the methodology of the SFP Guidance Report and that the HCLPF value is greater than the GMRS. The staff concludes that SFP SSCs were appropriately evaluated and that the licensee has demonstrated that there is high confidence the SFP structure is sufficiently robust to withstand ground motions with peak spectral acceleration up to and including the peak spectral acceleration of Callaway's GMRS.
SPENT FUEL POOL NON-STRUCTURAL EVALUATION Section 4.2 of the SFP Evaluation Guidance Report provides criteria for evaluating the non-structural aspects of the SFP, such as piping connections, fuel gates, and anti-siphoning devices, as well as SFP sloshing and heat up and boil-off of SFP water inventory. Additionally, page 4-11 of the SFP Evaluation Guidance Report provides a summary of the pertinent SFP non-structural parameters important to the methodology described in Section 4.2.
The licensee stated that it followed the SFP non-structural evaluation approach presented in the guidance report and provided site-specific data to confirm its applicability. The staff reviewed the non-structural information provided, which included Callaway's site-specific attributes, against the criteria described in the SFP Evaluation Guidance Report, and confirmed that the methods and conclusions are applicable to the Callaway site. Therefore, the staff concludes that the licensee adequately evaluated the non-structural considerations for SSCs whose failure could lead to potential drain-down of the SFP due to a seismic event. Further, the staff concludes that the licensee demonstrated that a potential drain-down of the SFP as a result of the reevaluated seismic hazard is unlikely.
AUDIT REPORT The July 6, 2017, generic audit plan describes the NRC staffs intention to issue an audit report that summarizes and documents the NRC's regulatory audit of licensee's submittals associated with reevaluated seismic hazard analyses. The NRC staffs Callaway audit was limited to the review of the calculation discussed above. An audit summary document is included as to this letter.
CONCLUSION The NRC staff reviewed the licensee's SFP evaluation report. Based on its review, the NRC staff concludes that the licensee's implementation of the SFP integrity evaluation met the criteria of the SFP Evaluation Guidance Report for Callaway and therefore, the licensee responded appropriately to Item 9 in Enclosure 1 of the NRC's 50.54(f) letter. The NRC staff further concludes that the licensee has demonstrated an adequate margin to preclude a potential drain-down of the SFP as a result of the reevalutaed seismic hazard at Callaway.
F. Diya If you have any questions, please contact me at (301) 415-3075 or via e-mail at Brett. Titus@nrc.gov.
Sincerely, Brett Titus, Senior Project Manager Beyond-Design-Basis Management Branch Division of Licensing Projects Office of Nuclear Reactor Regulation Docket No. 50-483
Enclosures:
- 1. Technical Review Checklist
- 2. NRG Staff Audit Summary cc w/encl: Distribution via Listserv
TECHNICAL REVIEW CHECKLIST BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO SPENT FUEL POOL EVALUATIONS FOR HIGH GROUND MOTION RESPONSE SPECTRUM SITES IMPLEMENTING NEAR-TERM TASK FORCE RECOMMENDATION 2.1 SEISMIC CALLAWAY PLANT, UNIT 1 DOCKET NO. 50-483 BACKGROUND By letter dated March 12, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12053A340), the U.S. Nuclear Regulatory Commission (NRC) issued a request for information to all power reactor licensees and holders of construction permits in active or deferred status, pursuant to Title 10 of the Code of Federal Regulations ( 10 CFR), Section 50.54(f) (hereafter referred to as the "50.54(f) letter"). Enclosure 1 of the 50.54(f) letter requests addressees to reevaluate the seismic hazard at their site using present-day methods and guidance for licensing new nuclear power plants, and identify actions to address or modify, as necessary, plant components affected by the reevaluated seismic hazards. , Item 4, of the 50.54(f) letter requested that licensees perform a comparison of the ground motion response spectrum (GMRS) with the safe shutdown earthquake (SSE). , Item 9, requests that, when the GMRS exceeds the SSE in the 1 to 10 Hertz (Hz) frequency range, a seismic evaluation be made of the spent fuel pool (SFP). More specifically, plants were asked to consider all seismically induced failures that can lead to draining of the SFP.
Additionally, by letter dated January 31, 2017 (ADAMS Accession No. ML17031A171 ), the Nuclear Energy Institute (NEI) submitted Electric Power Research Institute (EPRI) Report No.
3002009564 entitled, "Seismic Evaluation Guidance: Spent Fuel Pool Integrity Evaluation" (SFP Evaluation Guidance Report). The SFP Evaluation Guidance Report supports the completion of SFP evaluations for sites with reevaluated seismic hazard exceedance in the 1 to 10 Hz frequency range. The NRC endorsed the SFP Evaluation Guidance Report by letter dated February 28, 2017 (ADAMS Accession No. ML17034A408), as an acceptable method for licensees to use when responding to Item 9 in Enclosure 1 of the 50.54(f) letter. Licensee deviations from the SFP Evaluation Guidance should be discussed in their SFP evaluation submittal.
By letter dated October 3, 2017 (ADAMS Accession No. ML172768201 ), Union Electric Company, doing business as Ameren Missouri {the licensee), provided a SFP report in response to Enclosure 1, Item 9, of the 50.54(f) letter for Callaway Plant, Unit 1 (Callaway). The NRC staff performed its review of the licensee's submittal to assess whether the licensee responded appropriately to Item 9 in Enclosure 1 of the 50.54(f) letter. The NRC staff evaluated whether the SFP Guidance Report methodology has been followed when calculating the site-specific seismic capacity of the SFP, and that Callaway's site-specific values and conditions are within the acceptable limits and bounds considered for the non-structural evaluation criteria specified in the SFP Evaluation Guidance Report. The NRC staff also confirmed that the requested information in response to Item 9 of the 50.54(f) letter was provided.
A review checklist was used for consistency and efficiency. The application of this staff review is limited to the SFP evaluation as part of the seismic review as part of the Near-Term Task Force (NTTF} Recommendation 2.1.
Enclosure 1
NTTF Recommendation 2.1 Spent Fuel Pool Evaluations Technical Review Checklist for Callaway, Unit 1 Site Parameters:
I. Site-Specific GMRS The licensee:
- Used the site-specific GMRS hazard, consistent with the Yes information in the Seismic Hazard and Screening Report (SHSR) or its update, that was evaluated and accepted in the NRC staff assessment, when calculating the SFP high confidence of low probability of failure (HCLPF) value.
Notes from the reviewer:
- 1. The NRC staff reviewed the licensee's calculation AMN-12-CALC-001, Rev. 0, as a part of the audit process for Callaway. The staff notes that the calculation derives seismic input values for the Fuel Building from other seismic input values that were ultimately generated by the NRG-accepted GMRS. See conclusion below for details.
Deviation(s) or Deficiency(ies), and Resolution:
No deviations or deficiencies were identified.
The NRC staff concludes:
- The licensee's derivation of the Fuel Building In-Structure Response Spectra (ISRS) using enveloping, scaled, and smoothed data from the ISRS of the Auxiliary/Control Building (that was generated using the GMRS) is reasonable for the purposes of this calculation. Scaling of response spectra is a common practice in seismic evaluations, and Callaway's implementation of this practice is reasonable for this purpose.
Structural Parameters:
II. Seismic Design of the SFP Structure The licensee:
- Performed site-specific calculations to demonstrate that the limiting Yes SFP HCLPF capacity value is greater than the peak spectral acceleration of the site-specific GMRS.
Notes from the reviewer:
- 1. The NRC staff confirmed that the licensee followed the methodology described in the SFP Evaluation Guidance Report in calculation AMN-12-CALC-001, Rev. 0, to calculate a SFP HCLPF capacity. The resulting HCLPF value is greater than the site-specific GMRS; therefore, it is reasonable to conclude that the SFP has sufficient capacity to withstand a seismic event at least up to the GMRS without failure that would lead to a rapid draindown.
Deviation(s) or Deficiency(ies), and Resolution:
No deviations or deficiencies were identified.
The NRC staff concludes that:
- The SFP has sufficient capacity to withstand a seismic event at least up to the GMRS without failure that would lead to a rapid draindown.
Ill. SFP Structure Included in the Civil Inspection Program Performed in Accordance with Maintenance Rule The licensee:
- Stated that the SFP structure is included in the Civil Inspection Yes Program performed in accordance with Maintenance Rule (10 CFR 50.65).
Notes from the reviewer:
- 1. The licensee stated that the SFP structure is included in the Callaway Civil Inspection Program, Procedure ESP-ZZ-01013, including Appendices A, B, and C.
Deviation(s) or Deficiency(ies), and Resolution:
No deviations or deficiencies were identified.
The NRC staff concludes that:
- The SFP structure is included in the Civil Inspection Program Yes performed in accordance with Maintenance Rule (10 CFR 50.65).
Non-Structural Parameters:
IV. Applicability of Piping Evaluation The licensee:
- Stated that there are no piping penetrations attached to the SFP Yes more than 6 [feet] ft. below the surface of the water and cited plant drawings (M-23EC04, M-23EC06, and M-23EF12).
Notes from the reviewer:
- 1. The NRC staff reviewed available Final Safety Analysis Report (FSAR) drawing M-22EC01 and found the licensee's statement to be consistent with the General Notes of the FSAR drawing.
Deviation(s) or Deficiency(ies), and Resolution:
No deviations or deficiencies were identified.
The NRC staff concludes that:
- There are no piping penetrations attached to the SFP more than 6 ft. below the surface of the water.
V. Ductile Behavior of SFP Gates The licensee:
- Stated that the SFP gate is constructed from a ductile material (e.g . Yes aluminum or stainless steel alloys).
Notes from the reviewer:
- 1. The licensee stated that the SFP gates are constructed from ASTM A240, Type 304L, which is a stainless steel alloy. This is consistent with the materials specified in the SFP Evaluation Guidance Report to ensure ductile behavior of the gates.
Deviation(s) or Deficiency(ies), and Resolution:
No deviations or deficiencies were identified.
The NRC staff concludes that:
- The SFP gates are constructed from a material expected to exhibit ductile behavior under increased seismic demands.
VI. Siphoning Evaluation The licensee:
- Stated that anti-siphoning devices are installed on piping systems Yes that could lead to siphoning inventory from the SFP.
- In cases where anti-siphoning devices were not included on the NIA applicable piping, a description documenting the evaluation performed to determine the seismic adequacy of the piping is provided.
- Stated that the piping of the SFP cooling system cannot lead to rapid Yes drain down due to siphoning.
- Stated that no anti-siphoning devices are attached to 2" or smaller Yes piping with extremely large extended operators.
- Provided a seismic adequacy evaluation, in accordance with NIA NP-6041, for cases where active siphoning devices are attached to 2" or smaller piping with extremely large extended operators.
Notes from the reviewer:
- 1. The licensee stated that anti-siphoning holes are present in SFP-attached piping that could lead to siphoning of water. The staff verified that the FSAR supports this statement (FSAR Sections 9.1.3.2.1.1 and 9.1.3.3).
Deviation(s) or Deficiency(ies), and Resolution:
No deviations or deficiencies were identified.
The NRC staff concludes:
- Anti-siphoning devices exist in applicable piping systems that could Yes lead to siphoning water from the SFP.
- Piping of the SFP cooling system is not likely to lead to rapid Yes draindown due to siphoning.
- No active anti-siphoning devices are attached to 2" or smaller piping Yes with extremely large extended operators.
VII. Sloshing Evaluation The licensee:
- Specified the SFP dimensions (length, width, and depth). Yes
- Specified that the SFP dimensions are bounded by the dimensions Yes specified in the report (i.e., SFP length and width <125ft.; SFP depth >36ft.).
Notes from the reviewer:
- 1. SFP dimensions (Figure 2 of AMN-12-CALC-001, Rev. 0)
- SFP Length - 50 ft.
- SFP Width - 28.5 ft.
- SFP Depth - 41 ft.
- 2. Figure 4.2 of the SFP Evaluation Guidance Report shows site-specific results of the remaining water inventory used as the initial condition for evaporative losses which are evaluated in the next section of the EPRI Report and this checklist.
Deviation(s) or Deficiency(ies), and Resolution:
No deviations or deficiencies were identified.
The NRC staff concludes:
- SFP dimensions are bounded by the dimensions specified in the Yes report (i.e., SFP length and width <125ft.; SFP depth >36ft.).
VIII. Evaporation Evaluation The licensee:
- Provided the surface area of the plant's SFP. Yes
- Stated that the surface area of the plant's SFP is greater than Yes 500 ft2
- Provided the licensed reactor core thermal power. Yes
- Stated that the reactor core thermal power is less than 4,000 Yes megawatt thermal (MW1) per unit.
Notes from the reviewer:
- 1. Surface area of pool= 1425 ft2 (Figure 2 of AMN-12-CALC-001, Rev. 0)
- 2. Reactor thermal power= 3565 MW1 (FSAR Section 1.1.5)
Deviation(s) or Deficiency(ies), and Resolution:
No deviations or deficiencies were identified.
The NRC staff concludes:
- The surface area of the plant's SFP is greater than 500 ft 2 . Yes
- The reactor core thermal power is less than 4,000 MW1 per unit. Yes
==
Conclusions:==
The NRC staff reviewed the licensee's SFP evaluation report. Based on its review, the NRC staff concludes that the SFP Guidance Report methodology has been followed when calculating the site-specific seismic capacity of the SFP, and that Callaway's site-specific values and conditions are within the acceptable limits and bounds considered for the non-structural evaluation criteria specified in the SFP Evaluation Guidance Report. Therefore, the licensee responded appropriately to Item 9 in Enclosure 1 of the 50.54(f) letter. The NRC staff further concludes that the licensee has demonstrated an adequate margin to preclude a potential drain-down of the SFP as a result of the reevalutaed seismic hazard at Callaway.
AUDIT
SUMMARY
BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO CALLAWAY PLANT, UNIT 1 SPENT FUEL POOL EVALUATION ASSOCIATED WITH REEVALUATED SEISMIC HAZARD IMPLEMENTING NEAR-TERM TASK FORCE RECOMMENDATION 2.1: SEISMIC (EPID L-2017-JLD-0042)
BACKGROUND AND AUDIT BASIS By letter dated March 12, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12053A340), the U.S. Nuclear Regulatory Commission (NRC) issued a request for information pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Section 50.54(f) (hereafter referred to as the 50.54(f) letter). Enclosure 1 to the 50.54(f) letter requested that licensees reevaluate the seismic hazards for their sites using present-day methods and regulatory guidance used by the NRC staff when reviewing applications for early site permits and combined licenses.
By letter dated October 27, 2015 (ADAMS Accession No. ML15194A015), the NRC made a determination of which licensees were to perform: (1) an SPRA [seismic probabilistic risk assessment], (2) limited scope evaluations, or (3) no further actions based on a comparison of the reevaluated seismic hazard and the site's design-basis earthquake. (Note: Some plant-specific changes regarding whether an SPRA was needed or limited scope evaluations were needed at certain sites have occurred since the issuance of the October 27, 2015, letter.)
By letter dated July 6, 2017 (ADAMS Accession No. ML17177A446), the NRC issued a generic audit plan and entered into the audit process described in Office Instruction LIC-111, "Regulatory Audits", dated December 29, 2008 (ADAMS Accession No. ML082900195), to assist in the timely and efficient closure of activities associated with the letter issued pursuant to 10 CFR Part 50, Section 50.54(f). Callway Plant, Unit 1 (Callaway) was included in the list of applicable licensees.
REGULATORY AUDIT SCOPE AND METHODOLOGY The areas of focus for the regulatory audit are the information contained in the spent fuel pool (SFP) evaluation submittal and all associated and relevant supporting documentation used in the development of the SFP evaluation, but not limited to, methodology, process information, calculations, computer models, etc.
AUDIT ACTIVITIES The Callaway audit took place at the NRC Headquarters in Rockville, MD, beginning on July 6, 2017. Licensee personnel participated remotely, via email, from their respective offices. A list of the licensee staff and NRC staff that participated in the audit is contained in Table 1.
Enclosure 2
Table 1 NRC Staff Licensee Staff Name Title Name Title Brett Titus Project Manager Elizabeth Ptasznik Licensing Engineer Bruce Huhmann Supervising Engineer On November 8, 2017, the NRC staff requested, via email, that the licensee upload the calculation that was performed to determine the high-confidence low probability of failure (HCLPF) value for the SFP onto the licensee's ePortal (electronic reading room). The licensee uploaded calculation AMN-12-CALC-001, Rev. 0, onto the ePortal on November 8, 2017, as requested by the NRC staff.
DOCUMENTS AUDITED AMN-12-CALC-001, Rev. 0 OPEN ITEMS AND REQUEST FOR INFORMATION Following the review of the SFP HCLPF calculation, there were no open items identified by the NRC staff that required proposed closure paths, and there were no requests for information discussed or planned to be issued.
DEVIATIONS FROM AUDIT PLAN There were no deviations from the July 6, 2017, generic audit plan.
AUDIT CONCLUSION The issuance of this document, containing the staff's review of the SFP evaluation submittal, concludes the SFP audit process for Callaway.
NAME BTitus SLent MShams BHarris DATE 1/2/18 1/3/18 1/16/18 1/18/18 OFFICE NRR/DLP/PBMB/PM NAME BTitus DATE 1/23/18