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| | number = ML15240A134 | | | number = ML15240A134 |
| | issue date = 09/03/2015 | | | issue date = 09/03/2015 |
| | title = Sequoyah Nuclear Plant Units 1 & 2- Interim Staff Response to Reevaluated Flood Hazards Submitted in Response to 10 CFR50.54 Information Request - Flood Causing Mechanism Reevaluation | | | title = Interim Staff Response to Reevaluated Flood Hazards Submitted in Response to 10 CFR50.54 Information Request - Flood Causing Mechanism Reevaluation |
| | author name = Uribe J F | | | author name = Uribe J |
| | author affiliation = NRC/NRR/JLD | | | author affiliation = NRC/NRR/JLD |
| | addressee name = Shea J W | | | addressee name = Shea J |
| | addressee affiliation = Tennessee Valley Authority | | | addressee affiliation = Tennessee Valley Authority |
| | docket = 05000327, 05000328 | | | docket = 05000327, 05000328 |
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| | page count = 8 | | | page count = 8 |
| | project = TAC:MF6032, TAC:MF6033 | | | project = TAC:MF6032, TAC:MF6033 |
| | | stage = Other |
| }} | | }} |
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| =Text= | | =Text= |
| {{#Wiki_filter:QFFICIAL. USli ONbY SECURITY RELATED INFORMATION UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. Joseph W. Shea Vice President, Nuclear Licensing Tennessee Valley Authority 1101 Market Street, LP 3R-C Chattanooga, TN 37 402-2801 September 3, 2015 SUBJECT: SEQUOYAH NUCLEAR PLANT, UNITS 1AND2 -INTERIM STAFF RESPONSE TO REEVALUATED FLOOD HAZARDS SUBMITTED IN RESPONSE TO 10 CFR 50.54(f) INFORMATION REQUEST -CAUSING MECHANISM REEVALUATION (TAC NOS. MF6032 AND MF6033) Dear Mr. Shea: The purpose of this letter is to provide a summary of the U.S. Nuclear Regulatory Commission (NRC) staff's assessment of the re-evaluated flood-causing mechanisms described in the March 12, 2015 (Agencywide Document Access and Management System (ADAMS) Accession No. ML 15071A462), flood hazard reevaluation report (FHRR) submitted by Tennessee Valley Authority (TVA.the licensee) for Sequoyah Nuclear Plant, Units 1 and 2 (Sequoyah), as well as supplemental information resulting from requests for additional information and audits. By letter dated March 12, 2012, the NRC issued a request for information pursuant to Title 1 O of the Code of Federal Regulations, Section 50.54(f) (hereafter referred to as the 50.54(f) letter) (ADAMS Accession No. ML 12053A340). The request was issued as part of implementing lessons-learned from the accident at the Fukushima Dai-ichi nuclear power plant. Enclosure 2 to the 50.54(f) letter requested licensees to re-evaluate flood-causing mechanisms using present-day methodologies and guidance. Concurrently, with the reevaluation of flooding hazards, licensees were required to develop and implement mitigating strategies in accordance with NRC Order EA-12-049, "Requirements for Mitigation Strategies for Beyond-Design-Basis External Events" (ADAMS Accession No. ML 12054A735). On March 30, 2015, the Commission provided Staff Requirements Memoranda (SRM) (ADAMS Accession No. ML 15089A236) to COMSECY-14-0037, "Integration of Mitigating Strategies for Beyond-Design-Basis External Events and the Reevaluation of Flooding Hazards," dated November 21, 2014 (ADAMS Accession No. ML 14309A256), affirming that licensees need to address the reevaluated flooding hazards within their mitigating strategies for beyond-design-basis external events. The NRC staff has reviewed the information submitted by the licensee and has summarized the results of the review in the tables provided as Enclosure 1 to this letter. Table 1 provides the current design-basis flood hazard mechanisms. Enclosure 2 transmitted herewith contains Security-Related Information. When separated from the Enclosure, this document is decontrolled. 'OFFICIAL USE ONLYŽ SECURITY RELATED INFORMATION OFFICIAL' 'SE ONLY SECURITY RELAiTEO INFORMAiTION J. Shea -2 -Table 2 provides reevaluated flood hazard mechanisms; however, reevaluated hazard mechanisms bounded by the current design-basis (Table 1) are not included. Because Table 2 includes security-related information, Enclosure 1 contains the redacted version of Table 2. Enclosure 2 is withheld from public disclosure and restores the security-related information to Table 2. The NRC staff has concluded that the licensee's reevaluated flood hazards information, as summarized in the Enclosure, is suitable for the assessment of mitigating strategies developed in response to Order EA-12-049 (i.e., defines the mitigating strategies flood hazard information described in guidance documents currently being finalized by the industry and NRC staff) for Sequoyah. Further, the NRC staff has concluded that the licensee's reevaluated flood hazard information is a suitable input for other assessments associated with Near-Term Task Force Recommendation 2.1 "Flooding". The NRC staff plans to issue a staff assessment documenting the basis for these conclusions at a later time. In addition, NEI 12-06 "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide" is currently being revised. This revision will include a methodology to perform a Mitigating Strategies Assessment (MSA) with respect to the reevaluated flood hazards. Once this methodology is endorsed by the NRC, flood event duration parameters and applicable flood associated effects should be considered as part of the Sequoyah MSA. The NRC staff will evaluate the flood event duration parameters (including warning time and period of inundation) and flood-related associated effects developed by the licensee during the NRC staff's review of the MSA. As stated above, Table 2 of the enclosure to this letter describes the reevaluated flood hazards that exceed the current design-basis. In order to complete its response to the information requested by Enclosure 2 to the 50.54(f) letter, the licensee is expected to submit an integrated assessment or a focused evaluation, as appropriate, to address these reevaluated flood hazards, as described in the NRC letter, "Coordination of Request for Information Regarding Flooding Hazard Reevaluation and Mitigating Strategies for Beyond-Design-Basis External Events" (ADAMS Accession No. ML 15174A257). This letter describes the changes in the NRC's approach to the flood hazard reevaluations that were approved by the Commission in its SRM to COMSECY-15-0019, "Closure Plan forthe Reevaluation of Flooding Hazards for Operating Nuclear Power Plants" (ADAMS Accession No. ML 15209A682). OFFICIAb USI! ONbY SECURITY RELATED INFORMATION Ol=l=ICIAb USE ONbY SECURITY REbATEC INl=Ol'nll4TION J.Shea -3 -If you have any questions, please contact me at (301) 415-3809 or e-mail at Juan.Uribe@nrc.gov. Docket Nos. 50-327 and 50-328 Enclosures: 1) Summary of Results of Flooding Sincer ribe, Project Manager Hazards Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation Hazard Re-Evaluation Report (Redacted Version) 2) Summary of Results of Flooding Hazard Re-Evaluation Report (Non-Public Version) cc w/encl: Distribution via Listserv OFFICIAb. lislili QHkV SEGPBITY BEi AJFD INFORBUIION ENCLOSURE 1: SUMMARY TABLES OF REEVALUATED FLOOD HAZARD LEVELS-REDACTED VERSION Sequoyah, Units 1 & 2 Table 1. Current Design Basis Flood Hazards for Use in the MSA Mechanism Stillwater Waves/ I Design Basis Reference Elevation Run up Hazard Elevation -----------------------Local Intense Precipitation 705.7 ft msl Minimal 705.7 ft msl FHRR Section 3.4.1 Streams and Rivers Diesel Generator Building 722.0 ft msl 1.2 ft ! 723.2 ft msl FHRR Section 3.4.2 I FHRR Section 3.4.8.1 I i I ERCW Pumping Station 722.0 ft msl 4.2 ft I 726.2 ft msl FHRR Section 3.4.2 FHRR Sec.tion 3.4.8.1 i ' I Failure of Dams and Onsite ! Water Control/Storage I Structures I I 708.6 ft msl Not 708.6 ft msl FHRR Section 3.4.8.2 applicable Storm Surge i Not included Not included Not included FHRR Section 3.4.4 I in DB in DB in DB Seiche I Not included Not included Not included FHRR Section 3.4.4 in DB in DB in DB I Tsunami Not included Not included Not included FHRR Section 3.4.5 in DB in DB in DB Ice-Induced Flooding I Not included Not included Not included FHRR Section 3.4.6 in DB in DB in DB I I Sequoyah, Units 1 & 2 Table 1. Current Design Basis Flood Hazards for Use in the MSA r ------------------------------------------------Mechanism Stillwater Waves/ Design Basis Reference Elevation Run up Hazard Elevation Channel Migrations/Diversions Not included Not included Not included I FHRR Section 3.4.7 in DB in DB in DB Note: Reported values are rounded to the nearest one-tenth of a foot. | | {{#Wiki_filter:QFFICIAL. USli ONbY SECURITY RELATED INFORMATION UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 September 3, 2015 Mr. Joseph W. Shea Vice President, Nuclear Licensing Tennessee Valley Authority 1101 Market Street, LP 3R-C Chattanooga, TN 37402-2801 |
| Sequoyah, Units 1 & 2 Table 2. Reevaluated Flood Hazards for Flood-Causing Mechanisms for Use in the MSA ,-----------------l Mechanism Stillwater Waves/ Reevaluated Reference Elevation Run up Hazard Elevation Local Intense Precipitation I ! I I 706.3 ft msl I 706.3 ft msl Minimal FHRR Table 11-1 i ! I I I I I Streams and Rivers [Redacted] [Redacted] [Redacted] [Redacted] [Redacted] ---------------------------Note 1: The licensee is expected to develop flood event duration parameters and applicable flood associated effects to conduct the MSA. The staff will evaluate the flood event duration parameters (including warning time and period of inundation) and flood associated effects during its review of the MSA. -----, I Note 2: Reevaluated hazard mechanisms bounded by the current design basis (see Table 1) are not included in this table. Note 3: Reported values are rounded to the nearest one-tenth of a foot.
| | |
| OFFICIAL USE ONLY SECURITY RELATED INFORMATION J. Shea -3 -If you have any questions, please contact me at (301) 415-3809 or e-mail at Juan.Uribe@nrc.gov. Sincerely, IRA/ Juan F. Uribe, Project Manager Hazards Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation Docket Nos. 50-327 and 50-328 Enclosures: 1) Summary of Results of Flooding Hazard Re-Evaluation Report (Redacted Version) 2) Summary of Results of Flooding Hazard Re-Evaluation Report (Non-Public Version) cc w/encl: Distribution via Listserv DISTRIBUTION: PUBLIC JUribe, NRR RidsNrrDorlLpl2-2 Resource RidsRgn3MailCenter Resource RidsOpaMail Resource ARivera-Varona, NRO MWillingham, NRO MShams, NRR JLD R/F LQuinn-Willingham, NRO RidsNrrDorl Resource RidsNrrLASLent RidsAcrsAcnw_MailCtr Resource KErwin, NRO RRivera-Lugo, NRO RidsNRRJLD Resource RidsNroDsea Resource RidsNrrPMSequoyah Resource RidsOgcMailCenter Resource CCook, NRO ACampbell, NRO BHarvey, NRO ADAMS Accession Nos.: PKG ML 15240A163; LTR: ML 15240A134; ENCL: ML 15238B656 (PUBLIC) ML 15226A549 (NON-PUBLIC) *via email OFFICE NRR/JLD/JHMB/PM NRR/JLD/LA NRO/DSEA/RHM1/TR* NRO/DSEA/RHM2/BC* NAME JUribe SLent SBreithaupt ARiveraVarona DATE 8 I 28 /15 8 / 28 /15 8 / 17 /15 8 / 17 /15 OFFICE NRR/JLD/JHMB/BC NRR/JLD/JHMB/PM NAME MShams JUribe DATE 8 / 28 /15 9 / 3 /15 OFFICIAL RECORD COPY 10FFICIAL USE ONLYŽ SECURlff-RELATED INFORMATION
| | ==SUBJECT:== |
| }} | | SEQUOYAH NUCLEAR PLANT, UNITS 1AND2 - INTERIM STAFF RESPONSE TO REEVALUATED FLOOD HAZARDS SUBMITTED IN RESPONSE TO 10 CFR 50.54(f) INFORMATION REQUEST - FLOOD-CAUSING MECHANISM REEVALUATION (TAC NOS. MF6032 AND MF6033) |
| | |
| | ==Dear Mr. Shea:== |
| | |
| | The purpose of this letter is to provide a summary of the U.S. Nuclear Regulatory Commission (NRC) staff's assessment of the re-evaluated flood-causing mechanisms described in the March 12, 2015 (Agencywide Document Access and Management System (ADAMS) Accession No. ML15071A462), flood hazard reevaluation report (FHRR) submitted by Tennessee Valley Authority (TVA.the licensee) for Sequoyah Nuclear Plant, Units 1 and 2 (Sequoyah), as well as supplemental information resulting from requests for additional information and audits. |
| | By letter dated March 12, 2012, the NRC issued a request for information pursuant to Title 1O of the Code of Federal Regulations, Section 50.54(f) (hereafter referred to as the 50.54(f) letter) |
| | (ADAMS Accession No. ML12053A340). The request was issued as part of implementing lessons-learned from the accident at the Fukushima Dai-ichi nuclear power plant. Enclosure 2 to the 50.54(f) letter requested licensees to re-evaluate flood-causing mechanisms using present-day methodologies and guidance. Concurrently, with the reevaluation of flooding hazards, licensees were required to develop and implement mitigating strategies in accordance with NRC Order EA-12-049, "Requirements for Mitigation Strategies for Beyond-Design-Basis External Events" (ADAMS Accession No. ML12054A735). On March 30, 2015, the Commission provided Staff Requirements Memoranda (SRM) (ADAMS Accession No. ML15089A236) to COMSECY-14-0037, "Integration of Mitigating Strategies for Beyond-Design-Basis External Events and the Reevaluation of Flooding Hazards," dated November 21, 2014 (ADAMS Accession No. ML14309A256), affirming that licensees need to address the reevaluated flooding hazards within their mitigating strategies for beyond-design-basis external events. |
| | The NRC staff has reviewed the information submitted by the licensee and has summarized the results of the review in the tables provided as Enclosure 1 to this letter. Table 1 provides the current design-basis flood hazard mechanisms. |
| | Enclosure 2 transmitted herewith contains Security-Related Information. When separated from the Enclosure, this document is decontrolled. |
| | 'OFFICIAL USE ONLY' SECURITY RELATED INFORMATION |
| | |
| | OFFICIAL' 'SE ONLY SECURITY RELAiTEO INFORMAiTION J. Shea Table 2 provides reevaluated flood hazard mechanisms; however, reevaluated hazard mechanisms bounded by the current design-basis (Table 1) are not included. Because Table 2 includes security-related information, Enclosure 1 contains the redacted version of Table 2. is withheld from public disclosure and restores the security-related information to Table 2. |
| | The NRC staff has concluded that the licensee's reevaluated flood hazards information, as summarized in the Enclosure, is suitable for the assessment of mitigating strategies developed in response to Order EA-12-049 (i.e., defines the mitigating strategies flood hazard information described in guidance documents currently being finalized by the industry and NRC staff) for Sequoyah. Further, the NRC staff has concluded that the licensee's reevaluated flood hazard information is a suitable input for other assessments associated with Near-Term Task Force Recommendation 2.1 "Flooding". The NRC staff plans to issue a staff assessment documenting the basis for these conclusions at a later time. |
| | In addition, NEI 12-06 "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide" is currently being revised. This revision will include a methodology to perform a Mitigating Strategies Assessment (MSA) with respect to the reevaluated flood hazards. Once this methodology is endorsed by the NRC, flood event duration parameters and applicable flood associated effects should be considered as part of the Sequoyah MSA. The NRC staff will evaluate the flood event duration parameters (including warning time and period of inundation) and flood-related associated effects developed by the licensee during the NRC staff's review of the MSA. |
| | As stated above, Table 2 of the enclosure to this letter describes the reevaluated flood hazards that exceed the current design-basis. In order to complete its response to the information requested by Enclosure 2 to the 50.54(f) letter, the licensee is expected to submit an integrated assessment or a focused evaluation, as appropriate, to address these reevaluated flood hazards, as described in the NRC letter, "Coordination of Request for Information Regarding Flooding Hazard Reevaluation and Mitigating Strategies for Beyond-Design-Basis External Events" (ADAMS Accession No. ML15174A257). This letter describes the changes in the NRC's approach to the flood hazard reevaluations that were approved by the Commission in its SRM to COMSECY-15-0019, "Closure Plan forthe Reevaluation of Flooding Hazards for Operating Nuclear Power Plants" (ADAMS Accession No. ML15209A682). |
| | OFFICIAb USI! ONbY SECURITY RELATED INFORMATION |
| | |
| | Ol=l=ICIAb USE ONbY SECURITY REbATEC INl=Ol'nll 4 TION J.Shea If you have any questions, please contact me at (301) 415-3809 or e-mail at Juan.Uribe@nrc.gov. |
| | Sincer ribe, Project Manager Hazards Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation Docket Nos. 50-327 and 50-328 |
| | |
| | ==Enclosures:== |
| | : 1) Summary of Results of Flooding Hazard Re-Evaluation Report (Redacted Version) |
| | : 2) Summary of Results of Flooding Hazard Re-Evaluation Report (Non-Public Version) cc w/encl: Distribution via Listserv OFFICIAb. lislili QHkV SEGPBITY BEi AJFD INFORBUIION |
| | |
| | ENCLOSURE 1: |
| | |
| | ==SUMMARY== |
| | TABLES OF REEVALUATED FLOOD HAZARD LEVELS-REDACTED VERSION |
| | |
| | Sequoyah, Units 1 & 2 Table 1. Current Design Basis Flood Hazards for Use in the MSA Mechanism Stillwater Elevation Waves/ |
| | Run up IDesign Basis Hazard Reference Elevation -- --------- |
| | Local Intense Precipitation 705.7 ft msl Minimal 705.7 ft msl FHRR Section 3.4.1 Streams and Rivers Diesel Generator Building 722.0 ft msl 1.2 ft ! 723.2 ft msl FHRR Section 3.4.2 I FHRR Section 3.4.8.1 I |
| | i I |
| | ERCW Pumping Station 722.0 ft msl 4.2 ft I 726.2 ft msl FHRR Section 3.4.2 FHRR Sec.tion 3.4.8.1 i |
| | Failure of Dams and Onsite ! |
| | I Water Control/Storage I Structures I I 708.6 ft msl Not 708.6 ft msl FHRR Section 3.4.8.2 applicable Storm Surge i Not included Not included Not included FHRR Section 3.4.4 in DB in DB in DB I Seiche Not included Not included Not included FHRR Section 3.4.4 in DB in DB in DB I |
| | I Tsunami Not included Not included Not included FHRR Section 3.4.5 in DB in DB in DB Ice-Induced Flooding I Not included Not included Not included FHRR Section 3.4.6 in DB in DB in DB I |
| | I |
| | |
| | Sequoyah, Units 1 & 2 Table 1. Current Design Basis Flood Hazards for Use in the MSA r - |
| | Mechanism Stillwater Waves/ Design Basis Reference Elevation Run up Hazard Elevation Channel Migrations/Diversions Not included Not included Not included I FHRR Section 3.4.7 in DB in DB in DB Note: Reported values are rounded to the nearest one-tenth of a foot. |
| | |
| | Sequoyah, Units 1 & 2 Table 2. Reevaluated Flood Hazards for Flood-Causing Mechanisms for Use in the MSA Mechanism Stillwater Elevation Waves/ |
| | Reevaluated Reference -- ---, |
| | Run up Hazard Elevation I |
| | Local Intense Precipitation ! |
| | I I |
| | 706.3 ft msl Minimal 706.3 ft msl I FHRR Table 11-1 i I |
| | ! I I I I I Streams and Rivers |
| | [Redacted] [Redacted] [Redacted] [Redacted] [Redacted] |
| | l - -- - - - ---------- - - ---- -- --- |
| | Note 1: The licensee is expected to develop flood event duration parameters and applicable flood associated effects to conduct the MSA. The staff will evaluate the flood event duration parameters (including warning time and period of inundation) and flood associated effects during its review of the MSA. |
| | Note 2: Reevaluated hazard mechanisms bounded by the current design basis (see Table 1) are not included in this table. |
| | Note 3: Reported values are rounded to the nearest one-tenth of a foot. |
| | |
| | PKG ML15240A163; LTR: ML15240A134; ENCL: ML15238B656 (PUBLIC) |
| | ML15226A549 (NON-PUBLIC) *via email OFFICE NRR/JLD/JHMB/PM NRR/JLD/LA NRO/DSEA/RHM1/TR* NRO/DSEA/RHM2/BC* |
| | NAME JUribe SLent SBreithaupt ARiveraVarona DATE 8 I 28 /15 8 / 28 /15 8 / 17 /15 8 / 17 /15 OFFICE NRR/JLD/JHMB/BC NRR/JLD/JHMB/PM NAME MShams JUribe DATE 8 / 28 /15 9 / 3 /15}} |
Letter Sequence Other |
|---|
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Response to NRC Regulatory Issue Summary 2024-01, Preparation and Scheduling of Operator Licensing Examinations
ML24177A0282024-06-25025 June 2024
Emergency Plan Implementing Procedure Revisions
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1B-B Diesel Generator Failure - Final Significance Determination Letter
ML24145A1052024-05-29029 May 2024
301 Exam Approval Letter
ML24134A1762024-05-13013 May 2024
Submittal of 2023 Annual Radiological Environmental Operating Report
CNL-24-040, Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure Revisions2024-05-0808 May 2024
Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure Revisions
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Providing Supplemental Information to Apparent Violation
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10 CFR 50.46 Annual Report for Sequoyah Nuclear Plant Units 1 and 2
ML24116A2612024-04-25025 April 2024
Interim Report of a Deviation or Failure to Comply - Transducer Model 8005N
ML24114A0482024-04-23023 April 2024
Annual Radioactive Effluent Release Report for 2023 Monitoring Period
CNL-24-037, Clinch River, Sequoyah, Units 1 and 2, Watts Bar, Unit 1 and 2, Nuclear Quality Assurance Plan, TVA-NQA-PLN89-A, Revision 422024-04-22022 April 2024
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Tennessee Multi-Sector Permit (Tmsp), 2024 Annual Discharge Monitoring Report for Outfalls SW-3, SW-3, and SW-9
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Discharge Monitoring Report (Dmr), March 2024
CNL-24-024, Hydrologic Engineering Center River Analysis System Project Milestone Status Update2024-04-17017 April 2024
Hydrologic Engineering Center River Analysis System Project Milestone Status Update
CNL-24-033, Central Emergency Control Center Emergency Plan Implementing Procedure Revisions2024-04-17017 April 2024
Central Emergency Control Center Emergency Plan Implementing Procedure Revisions
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Cycle 27 Core Operating Limits Report Revision 0
ML24032A0202024-01-31031 January 2024
NPDES Biocide/Corrosion Treatment Plan Annual Report, Cy 2023
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Issuance of Amendment Nos. 366 and 360; 164 and 71 Regarding the Adoption of TSTF-567, Revision 1, Add Containment Sump TS to Address GSI-191 Issues
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ML24011A3202024-01-11011 January 2024
Submittal of Discharge Monitoring Report (Dmr), December 2023
IR 05000327/20234422024-01-11011 January 2024
95001 Supplemental Inspection Report 05000327/2023442 and 05000328/2023442 and Follow-Up Assessment Letter
ML24011A3162024-01-11011 January 2024
Submittal of Discharge Monitoring Report (Dmr), August 2023
ML24011A3192024-01-11011 January 2024
Submittal of Discharge Monitoring Report (Dmr), November 2023
ML24011A3172024-01-11011 January 2024
Submittal of Discharge Monitoring Report (Dmr), September 2023
ML24011A3182024-01-11011 January 2024
Submittal of Discharge Monitoring Report (Dmr), October 2023
ML24010A2132024-01-10010 January 2024
CFR 21.21 Final Report Regarding Siemens Medium Voltage Circuit Breakers
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Response to NRCs November 8, 2023, Request for Additional Information - Related to Independent Spent Fuel Storage Installation
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Application to Revise Function 5 of Technical Specification Table 3.3.2-1, Engineered Safety Feature Actuation System Instrumentation, for the Sequoyah Nuclear Plant and Watts Bar Nuclear Plant (SQN-TS-23-02 and WBN-TS-23-08)
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Integrated Inspection Report 05000327/2023003 and 05000328/2023003
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Revisions to the Sequoyah Nuclear Plant Units 1 and 2 Technical Requirements Manual
2024-07-09
[Table view] |
Text
QFFICIAL. USli ONbY SECURITY RELATED INFORMATION UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 September 3, 2015 Mr. Joseph W. Shea Vice President, Nuclear Licensing Tennessee Valley Authority 1101 Market Street, LP 3R-C Chattanooga, TN 37402-2801
SUBJECT:
SEQUOYAH NUCLEAR PLANT, UNITS 1AND2 - INTERIM STAFF RESPONSE TO REEVALUATED FLOOD HAZARDS SUBMITTED IN RESPONSE TO 10 CFR 50.54(f) INFORMATION REQUEST - FLOOD-CAUSING MECHANISM REEVALUATION (TAC NOS. MF6032 AND MF6033)
Dear Mr. Shea:
The purpose of this letter is to provide a summary of the U.S. Nuclear Regulatory Commission (NRC) staff's assessment of the re-evaluated flood-causing mechanisms described in the March 12, 2015 (Agencywide Document Access and Management System (ADAMS) Accession No. ML15071A462), flood hazard reevaluation report (FHRR) submitted by Tennessee Valley Authority (TVA.the licensee) for Sequoyah Nuclear Plant, Units 1 and 2 (Sequoyah), as well as supplemental information resulting from requests for additional information and audits.
By letter dated March 12, 2012, the NRC issued a request for information pursuant to Title 1O of the Code of Federal Regulations, Section 50.54(f) (hereafter referred to as the 50.54(f) letter)
(ADAMS Accession No. ML12053A340). The request was issued as part of implementing lessons-learned from the accident at the Fukushima Dai-ichi nuclear power plant. Enclosure 2 to the 50.54(f) letter requested licensees to re-evaluate flood-causing mechanisms using present-day methodologies and guidance. Concurrently, with the reevaluation of flooding hazards, licensees were required to develop and implement mitigating strategies in accordance with NRC Order EA-12-049, "Requirements for Mitigation Strategies for Beyond-Design-Basis External Events" (ADAMS Accession No. ML12054A735). On March 30, 2015, the Commission provided Staff Requirements Memoranda (SRM) (ADAMS Accession No. ML15089A236) to COMSECY-14-0037, "Integration of Mitigating Strategies for Beyond-Design-Basis External Events and the Reevaluation of Flooding Hazards," dated November 21, 2014 (ADAMS Accession No. ML14309A256), affirming that licensees need to address the reevaluated flooding hazards within their mitigating strategies for beyond-design-basis external events.
The NRC staff has reviewed the information submitted by the licensee and has summarized the results of the review in the tables provided as Enclosure 1 to this letter. Table 1 provides the current design-basis flood hazard mechanisms.
Enclosure 2 transmitted herewith contains Security-Related Information. When separated from the Enclosure, this document is decontrolled.
'OFFICIAL USE ONLY' SECURITY RELATED INFORMATION
OFFICIAL' 'SE ONLY SECURITY RELAiTEO INFORMAiTION J. Shea Table 2 provides reevaluated flood hazard mechanisms; however, reevaluated hazard mechanisms bounded by the current design-basis (Table 1) are not included. Because Table 2 includes security-related information, Enclosure 1 contains the redacted version of Table 2. is withheld from public disclosure and restores the security-related information to Table 2.
The NRC staff has concluded that the licensee's reevaluated flood hazards information, as summarized in the Enclosure, is suitable for the assessment of mitigating strategies developed in response to Order EA-12-049 (i.e., defines the mitigating strategies flood hazard information described in guidance documents currently being finalized by the industry and NRC staff) for Sequoyah. Further, the NRC staff has concluded that the licensee's reevaluated flood hazard information is a suitable input for other assessments associated with Near-Term Task Force Recommendation 2.1 "Flooding". The NRC staff plans to issue a staff assessment documenting the basis for these conclusions at a later time.
In addition, NEI 12-06 "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide" is currently being revised. This revision will include a methodology to perform a Mitigating Strategies Assessment (MSA) with respect to the reevaluated flood hazards. Once this methodology is endorsed by the NRC, flood event duration parameters and applicable flood associated effects should be considered as part of the Sequoyah MSA. The NRC staff will evaluate the flood event duration parameters (including warning time and period of inundation) and flood-related associated effects developed by the licensee during the NRC staff's review of the MSA.
As stated above, Table 2 of the enclosure to this letter describes the reevaluated flood hazards that exceed the current design-basis. In order to complete its response to the information requested by Enclosure 2 to the 50.54(f) letter, the licensee is expected to submit an integrated assessment or a focused evaluation, as appropriate, to address these reevaluated flood hazards, as described in the NRC letter, "Coordination of Request for Information Regarding Flooding Hazard Reevaluation and Mitigating Strategies for Beyond-Design-Basis External Events" (ADAMS Accession No. ML15174A257). This letter describes the changes in the NRC's approach to the flood hazard reevaluations that were approved by the Commission in its SRM to COMSECY-15-0019, "Closure Plan forthe Reevaluation of Flooding Hazards for Operating Nuclear Power Plants" (ADAMS Accession No. ML15209A682).
OFFICIAb USI! ONbY SECURITY RELATED INFORMATION
Ol=l=ICIAb USE ONbY SECURITY REbATEC INl=Ol'nll 4 TION J.Shea If you have any questions, please contact me at (301) 415-3809 or e-mail at Juan.Uribe@nrc.gov.
Sincer ribe, Project Manager Hazards Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation Docket Nos. 50-327 and 50-328
Enclosures:
- 1) Summary of Results of Flooding Hazard Re-Evaluation Report (Redacted Version)
- 2) Summary of Results of Flooding Hazard Re-Evaluation Report (Non-Public Version) cc w/encl: Distribution via Listserv OFFICIAb. lislili QHkV SEGPBITY BEi AJFD INFORBUIION
ENCLOSURE 1:
SUMMARY
TABLES OF REEVALUATED FLOOD HAZARD LEVELS-REDACTED VERSION
Sequoyah, Units 1 & 2 Table 1. Current Design Basis Flood Hazards for Use in the MSA Mechanism Stillwater Elevation Waves/
Run up IDesign Basis Hazard Reference Elevation -- ---------
Local Intense Precipitation 705.7 ft msl Minimal 705.7 ft msl FHRR Section 3.4.1 Streams and Rivers Diesel Generator Building 722.0 ft msl 1.2 ft ! 723.2 ft msl FHRR Section 3.4.2 I FHRR Section 3.4.8.1 I
i I
ERCW Pumping Station 722.0 ft msl 4.2 ft I 726.2 ft msl FHRR Section 3.4.2 FHRR Sec.tion 3.4.8.1 i
Failure of Dams and Onsite !
I Water Control/Storage I Structures I I 708.6 ft msl Not 708.6 ft msl FHRR Section 3.4.8.2 applicable Storm Surge i Not included Not included Not included FHRR Section 3.4.4 in DB in DB in DB I Seiche Not included Not included Not included FHRR Section 3.4.4 in DB in DB in DB I
I Tsunami Not included Not included Not included FHRR Section 3.4.5 in DB in DB in DB Ice-Induced Flooding I Not included Not included Not included FHRR Section 3.4.6 in DB in DB in DB I
I
Sequoyah, Units 1 & 2 Table 1. Current Design Basis Flood Hazards for Use in the MSA r -
Mechanism Stillwater Waves/ Design Basis Reference Elevation Run up Hazard Elevation Channel Migrations/Diversions Not included Not included Not included I FHRR Section 3.4.7 in DB in DB in DB Note: Reported values are rounded to the nearest one-tenth of a foot.
Sequoyah, Units 1 & 2 Table 2. Reevaluated Flood Hazards for Flood-Causing Mechanisms for Use in the MSA Mechanism Stillwater Elevation Waves/
Reevaluated Reference -- ---,
Run up Hazard Elevation I
Local Intense Precipitation !
I I
706.3 ft msl Minimal 706.3 ft msl I FHRR Table 11-1 i I
! I I I I I Streams and Rivers
[Redacted] [Redacted] [Redacted] [Redacted] [Redacted]
l - -- - - - ---------- - - ---- -- ---
Note 1: The licensee is expected to develop flood event duration parameters and applicable flood associated effects to conduct the MSA. The staff will evaluate the flood event duration parameters (including warning time and period of inundation) and flood associated effects during its review of the MSA.
Note 2: Reevaluated hazard mechanisms bounded by the current design basis (see Table 1) are not included in this table.
Note 3: Reported values are rounded to the nearest one-tenth of a foot.
PKG ML15240A163; LTR: ML15240A134; ENCL: ML15238B656 (PUBLIC)
ML15226A549 (NON-PUBLIC) *via email OFFICE NRR/JLD/JHMB/PM NRR/JLD/LA NRO/DSEA/RHM1/TR* NRO/DSEA/RHM2/BC*
NAME JUribe SLent SBreithaupt ARiveraVarona DATE 8 I 28 /15 8 / 28 /15 8 / 17 /15 8 / 17 /15 OFFICE NRR/JLD/JHMB/BC NRR/JLD/JHMB/PM NAME MShams JUribe DATE 8 / 28 /15 9 / 3 /15
