ML15212A727
| ML15212A727 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 09/04/2015 |
| From: | Victor Hall Japan Lessons-Learned Division |
| To: | Entergy Operations |
| Minarik, Anthony 415-6185 | |
| References | |
| TAC MF3675 | |
| Download: ML15212A727 (8) | |
Text
Vice President, Operations Entergy Operations, Inc.
River Bend Station 5485 U.S. Highway 61 N St. Francisville, LA 70775 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 September 4, 2015
SUBJECT:
RIVER BEND 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. MF3675)
Dear Sir or Madam:
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, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14073A647), flood hazard reevaluation report (FHRR) submitted by Entergy Operations, Inc.
(Entergy, the licensee) for River Bend Station, Unit 1 (River Bend), 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 10 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 COM-SECY-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 flood hazard information submitted by the licensee and has summarized the results of the review in the tables provided as an Enclosure to this letter.
Table 1 provides the current design-basis flood hazard mechanisms. Table 2 provides the reevaluated flood hazard mechanisms; however, the reevaluated flood hazard mechanisms bounded by the current design-basis (Table 1) are not included.
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 River Bend. Further, the 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 River Bend 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 NRC letter, "Coordination of Request for Information Regarding Flooding Hazard Reevaluation and Mitigating Strategies for Beyond Design Bases 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).
If you have any questions, please contact me at (301) 415-6197 or e-mail at Victor.Hall@nrc.gov.
Docket No. 50-458
Enclosure:
Summary of Results of Flooding Hazard Re-Evaluation Report cc w/encl: Distribution via Listserv Victor E. Hall, Senior Project Manager Hazards Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation
ENCLOSURE:
SUMMARY
TABLES OF REEVALUATED FLOOD HAZARD LEVELS
River Bend, Unit 1 Table 1. Current Design Basis Flood Hazards for Use in the MSA I
Mechanism Stillwater I
Waves/
Design Basis Reference I
Elevation I
Run up Hazard I
Elevation
- --1 Local Intense Precipitation I
Unit 1 96.0 ft MSL Not 96.0 ft MSL FHRR Table 4.1-1 applicable I
I 1 Unit 2 80.3 ft MSL Not 80.3 ft MSL FHRR Table4.1-1 applicable Streams and Rivers I
West Creek PMF 94.3 ft MSL Not 94.3 ft MSL FHRR Table 4.1-4 applicable Mississippi River 54.5 ft MSL Not 54.5 ft MSL FHRR Table 4.1-1 applicable Grants Bayou 101.8 ft MSL Not 101.8 ft MSL FHRR Table 4.1-1 I
applicable I
I I
Failure of Dams and Onsite Water Control/Storage Structures No impact on No impact on No impact on the site the site the site FHRR Table 4.1-1 identified identified identified I
' Storm Surge I
No impact on No impact on No impact on the site the site the site FHRR Table 4.1-1 I
identified identified identified i i Seiche I
No impact on No impact on No impact on the site the site the site FHRR Table 4.1-1 identified identified identified I
No impact on I I
Tsunami No impact on No impact on I
the site the site the site FHRR Table4.1-1 I
identified identified I
identified I
I I
I I
I I
I
River Bend, Unit 1 Table 1. Current Design Basis Flood Hazards for Use in the MSA Mechanism Stillwater Waves/
Design Basis Reference Elevation Run up Hazard Elevation
' Ice-Induced Flooding I
No impact on No impact on No impact on I the site the site the site FHRR Table 4.1-1 identified identified identified i
Channel Migrations/Diversions No impact on No impact on No impact on the site the site the site FHRR Table 4.1-1 I
identified identified identified I
i I
Note: Reported values are rounded to the nearest one-tenth of a foot
River Bend, Unit 1 Table 2. Reevaluated Flood Hazards for Flood-Causing Mechanisms for Use in the MSA r--
~-
I I Reevaluated I Mechanism Stillwater Waves/
Reference Elevation I
Run up Hazard Elevation Local Intense Precipitation I
I I
I Unit 1 98.3 ft MSL Minimal 98.3 ft MSL FHRR Tables 4.1-1, 4.1-2 & 4.1-3 Streams and Rivers i
West Creek PMF 95.1 ft MSL Not 95.1 ft MSL FHRR Table 4.1-4 applicable Mississippi River 59.7 ft MSL Not 59.7 ft MSL FHRR Table 4.1-1 applicable 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 ML15230A010 LTR: ML15212A727; ENCL: ML15219A667 *via email OFFICE NRR/JLD/JHMB/PM NRR/JLD/LA NRO/DSEA/RHM2/TR*
NRO/DSEA/RHM2/BC*
NAME AMinarik Slent WSharp ARivera-Varona DATE 8 / 18 /15 7/31/15 08/17/15 08/17/15 OFFICE NRR/JLD/JHMB/BC OGG*
NRR/JLD/JHMB/PM NAME MS hams SClark VHall DATE 8 / 18 /15 08/14/15 09/04/15