ML15355A087
| ML15355A087 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 12/22/2015 |
| From: | Tekia Govan Japan Lessons-Learned Division |
| To: | Cortopassi L Omaha Public Power District |
| Govan, Tekia NRR/JLD 415-6197 | |
| References | |
| TAC MF4711 | |
| Download: ML15355A087 (8) | |
Text
OFFICIAL USE ONLY SECURITY RELATED INFORMATION UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. Louis Cortopassi Site Vice President and Chief Nuclear Officer Omaha Public Power District Fort Calhoun Station Mail Stop FC-2-4 9610 Power Lane Blair, NE 68008 December 22, 2015
SUBJECT:
FORT CALHOUN STATION, UNIT 1-INTERIM STAFF RESPONSE TO REEVALUATED FLOOD HAZARDS SUBMITTED IN RESPONSE TO 10 CFR 50.54(f) INFORMATION REQUEST-FLOOD-CAUSING MECHANISM REEVALUATION (TAC NO. MF4711)
Dear Mr. Cortopassi:
The purpose of this letter is to provide a summary of the U.S. Nuclear Regulatory Commission (NRC) staff's assessment of the reevaluated flood-causing mechanisms described in the February 4, 2015 (Agencywide Documents Access and Management System (ADAMS)
Accession No. ML15042A127), flood hazard reevaluation report (FHRR) submitted by Omaha Public Power District (the licensee) for Fort Calhoun Station, Unit 1 (Fort Calhoun), 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. 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 reevaluate 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.
Enclosure two transmitted herewith contains Security-Related Information. When separated from the Enclosure, this document is decontrolled.
OFFICIAL USE ONLY SECURITY RELATED INFORMATION
OFFICIAL USE ONLY SECURITY RELATED INFORMATION 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. 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 Fort Calhoun. 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, Nuclear Energy Institute (NEI) guidance document 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 Fort Calhoun 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 for the Reevaluation of Flooding Hazards for Operating Nuclear Power Plants" (ADAMS Accession No. ML15209A682).
OFFICIAL USE ONLY SECURITY RELATED INFORMATION
OFFICIAL USE ONLY SECURITY RELATED INFORMATION If you have any questions, please contact me at (301) 415-6197 or e-mail at tekia.govan@nrc.gov.
Docket No. 50-285
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 Sincerely, Tekia Govan, Project Manager Hazards Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation OFFICIAL USE ONLY SECURITY RELATED INFORMATION
ENCLOSURE 1:
SUMMARY
TABLES OF REEVALUATED FLOOD HAZARD LEVELS
Fort Calhoun Station, Unit 1 Table 1. Current Design Basis Flood Hazards for Use in the MSA 1 Mechanism Stillwater Waves/
Design Basis Reference Elevation Run up Hazard Elevation i Local Intense Precipitation Not included Not included Not included FHRR Table 3.14-1 in DB in DB in DB Streams and Rivers I
Missouri River I
1,014.5 ft I
Not 1,014.5 ft FHRR Table 3.14-1 NAVD88 applicable I NAVD88 I
Failure of Dams and Onsite Water Control/Storage Structures
[Redacted]
[Redacted]
I [Redacted]
[Redacted]
[Redacted]
' Storm Surge I
No Impact No Impact No Impact FHRR Table 3.14-1 I
on the Site on the Site on the Site Identified Identified Identified Seiche No Impact No Impact No Impact FHRR Table 3.14-1 on the Site on the Site on the Site Identified Identified Identified
~----
Tsunami No Impact No Impact No Impact on the Site on the Site on the Site FHRR Table 3.14-1 Identified Identified Identified Ice-Induced Flooding Not included Not included Not included FHRR Table 3.14-1 in DB in DB in DB I
I Channel Migrations/Diversions I
Not included Not included Not included FHRR Table 3.14-1 in DB in DB in DB Note 1: Reported values are rounded to the nearest one-tenth of a foot.
Fort Calhoun Station, Unit 1 Table 2. Reevaluated Flood Hazards for Flood-Causing Mechanisms for Use in the MSA 1*2*3 Mechanism Stillwater Waves/
Reevaluated Reference Elevation Run up Hazard Elevation Local Intense Precipitation I
I Zone A 1,006.0 ft Minimal 1,006.0 ft FHRR Table 3.14-1 NAVD88 NAVD88 I
Streams and Rivers I
I I
Main Building Complex 1 1,010.4 ft 8.1 ft 1,018.5 ft I
FHRR Table 2.2-13 NAVD88 NAVD88 Main Building Complex 2 1,010.3 ft 7.9 ft 1,018.2 ft I
FHRR Table 2.2-13 I
NAVD88 NAVD88 I
Main Building Complex 3 I
1,010.4 ft 1,019.4 ft 9.0 ft i
FHRR Table 2.2-13 I
NAVD88 NAVD88 I
Main Building Complex 4 1,010.6 ft 4.3 ft 1,014.9ft I
FHRR Table 2.2-13 NAVD88 NAVD88 I
ISFSI 1,010.6ft 3.4 ft 1,014.0ft FHRR Table 2.2-13 NAVD88 I
NAVD88 I
Failure of Dams and Onsite Water Control/Storage Structures3
[Redacted]4 (Redacted]
[Redacted]
[Redacted]
[Redacted]
i
[Redacted]
Note 5 ----------------------------------------
[Redacted]
Note 5 ----------------------------------------
(Redacted]
Note 5 ----------------------------------------
Fort Calhoun Station, Unit 1 Table 2. Reevaluated Flood Hazards for Flood-Causing Mechanisms for Use in the MSA 1*2*3 Mechanism
[Redacted]
[Redacted]
[Redacted]
Ice-Induced Flooding Channel Migration/Diversion Stillwater Elevation Waves/
Run up Reevaluated Hazard Elevation Reference
Note 5 ----------------------------------------
Note 5 ----------------------------------------
Note 5 ----------------------------------------
1,006.1 ft NAVD88 Not applicable 1,006.1 ft NAVD88
Note 6 --------------------
FHRR Table 3.14-1 FHRR Sections 2.8 and 3.8 Note 1: Reevaluated hazard mechanisms bounded by the current design basis (see Table 1) are not included in this table.
Note 2: Reported values are rounded to the nearest one-tenth of a foot.
Note 3: 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 4: Flood height informed by use of 2-D model.
Note 5: The licensee is expected to update and submit these scenarios to the NRC by September 30, 2016, because evaluations of these scenarios using the 2-D model are not available. Reevaluated flood elevations using the 2-D model are expected to be bounded by the elevation from the [Redacted] Failure. However, the associated effects and flood event durations will differ from the [Redacted] Failure scenario and should be separately evaluated and provided in the September 30, 2016 submittal.
Note 6: Channel Migration/Diversion is dependent on the results of Streams and Rivers, Failure of Dams, and Onsite Water Control/Storage Structures scenarios in Table 2. It is expected that the water elevations for Channel Migration/
Diversion would be bounded by these associated scenarios, however the associated effects may be different. The licensee is expected to complete the evaluation for Channel Migration/Diversion, including the associated effects, and provided the results in the September 30, 2016 submittal.
PKG ML15355A099; L TR: ML15355A087; ENCL 1: ML15349A931 (PUBLIC);
ENCL 2: ML15349A926 (NON-PUBLIC)
- via email OFFICE NRR/JLD/JHMB/PM NRR/JLD/LA NRO/DSEA/RHM1fTR*
NRO/DSEA/RHM1fTL*
NAME TGovan Slent KSee KErwin DATE 12/21/2015 12/21/2015 12/17/2015 12/17/2015 OFFICE NRR/JLD/JHMB/BC NRR/JLD/JHMB/PM NAME MShams TGovan DATE 12/21/2015 12/22/2015