ML17150A260
| ML17150A260 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 06/09/2017 |
| From: | John Marshall Japan Lessons-Learned Division |
| To: | Higginbotham K Nebraska Public Power District (NPPD) |
| Govan, Tekia NRR/JLD 301-415-6197 | |
| Shared Package | |
| ML17150A140 | List: |
| References | |
| Download: ML17150A260 (4) | |
Text
OFFICIAL USE ONLY-SECURITY-RELATED INFORMATION UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. Kenneth Higginbotham Vice President-Nuclear and CNO Nebraska Public Power District Cooper Nuclear Station 72676 648A Avenue P.O. Box 98 Brownville, NE 68321 June 9, 2017
SUBJECT:
COOPER NUCLEAR STATION-NRG RESPONSE TO NEBRASKA PUBLIC POWER DISTRICT'S REQUEST TO OBTAIN U.S. ARMY CORPS OF ENGINEERS INFORMATION TO ADDRESS RECOMMENDATION 2.1-FLOODING OF THE NEAR-TERM TASK FORCE REVIEW OF INSIGHTS FROM THE FUKUSHIMA DIA-ICHI ACCIDENT
Dear Mr. Higginbotham:
This letter provides the U.S. Nuclear Regulatory Commission's (NRC's) response to the letter received from Nebraska Public Power District (NPPD, the licensee) on October 14, 2016 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML16293A590, Non-Public), requesting access to design and operating information from the U.S. Army Corps of Engineers (USAGE) related to the Missouri River dam system. The licensee's letter stated that the request for information is needed to support the development of the integrated assessment for the Cooper Nuclear Station (Cooper) with regard to dam failure.
Background
By letter dated March 12, 2012, the 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) "Conditions of license" (hereafter referred to as the "50.54(f) letter). The request was issued in connection with implementing lessons-learned from the 2011 accident at the Fukushima Dai-ichi nuclear power plant, as documented in The Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident." Enclosure 2 to the 50.54(f) letter requested that licensees reevaluate flood 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. For the sites where the reevaluated flood exceeds the design-basis, the licensees are expected to perform an integrated assessment or a focused evaluation to identify potential opportunities for safety enhancements to address the reevaluated hazard.
A portion of this letter contains Security-Related Information. When redacted, this letter is DECONTROLLED.
OFFICIAL USE ONLY-SECURITY-RELATED INFORMATION
OFFICIAL USE ONLY-SECURITY-RELATED INFORMATION By letter dated December 22, 2015 (ADAMS Accession No. ML15355A416), the NRC staff issued an interim staff response letter that provided a summary of the staff's assessment of the reevaluated flood-causing mechanisms described in the February 3, 2015 (ADAMS Accession No. ML15041A523), flood hazard reevaluation report submitted by NPPD for Cooper. The interim response letter identified local intense precipitation, streams and rivers, failure of dams and onsite water control/storage structures, ice-induced flooding, and channel migration/diversion as flood hazard mechanisms that exceeded the current design basis at the Cooper site. The letter further indicated that the site's response with respect to these flood hazards will need to be further evaluated by the licensee as part of an integrated assessment or focused evaluation.
On September 19, 2016 (ADAMS Accession No. ML16334A473), the NRC staff held a closed meeting with the licensee to discuss the approach for the analysis of dams that will be submitted as part of the integrated assessment for Cooper. As a result of this meeting, on October 14, 2016, NPPD submitted a request for access to design and operation information from the USACE for the Missouri River dam system. The purpose of the request was for NPPD to estimate the likelihood of a flood exceeding the consequential flooding conditions at the site due to dam failure such that NPPD can develop the appropriate coping mechanism to maintain the key safety functions.
NRC Response The NRC staff discussed the October 14, 2016, NPPD request with the USAGE. This discussion included NPPD's use of guidance provided in Nuclear Energy Institute (NEI) 16-05, Revision 1, "External Flooding Assessment Guidelines." According to that guidance, the licensee can provide a qualitative discussion utilizing appropriately justified generic studies and information to describe the likelihood of the flood severity associated with reaching and exceeding the consequential flooding conditions.
In response to the discussion between the NRC and the USACE staff regarding the NPPD request, the USACE responded to the NRC by letter dated April 25, 201 ?(ADAMS Accession No. ML17129A414, Non-Public).
Given the USACE estimates of consequential flooding frequency due to dam failure at the Cooper site, the NRC staff finds that NPPD can focus its portion of the integrated assessment addressing dam failure on demonstrating Cooper's ability to cope with the dam failure flood-causing mechanism through an effective mitigation strategy, as described in Section 8.1 of NEI 16-05. In addition, the NRC staff expects NPPD to address the remaining flood-causing mechanisms discussed in the NRC December 22, 2015, letter within its integrated assessment or through a focused evaluation, as appropriate.
OFFICIAL USE ONLY-SECURITY-RELATED INFORMATION
Pkg: ML17150A140; NON-PUBLIC Letter ML17116A266; PUBLIC Letter ML17150A260
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