ML16250A018

Request for Deferral of Actions Related to Beyond-Design-Basis External Events Flooding Actions - Commitment Changes

ML16250A018
Person / Time
Site:	Pilgrim
Issue date:	08/18/2016
From:	Dent J Entergy Nuclear Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
2.16.047
Download: ML16250A018 (3)

Text

~Entergy Entergy Nuclear Operations, Inc.

Pilgrim Nuclear Power Station 600 Rocky Hill Road Plymouth, MA 02360 John A. Dent, Jr.

Site Vice President August18,2016 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

SUBJECT:

Request for Deferral of Actions Related to Beyond-Design-Basis External Events Flooding Actions - Commitment Changes Pilgrim Nuclear Power Station Docket No. 50-293 Renewed License No. DPR-35 LETTER NUMBER: 2.16.047

REFERENCES:

1. Notification of Permanent Cessation of Power Operations, November 10, 2015 (ML15328A053)

2. Coordination of Requests for Information Regarding Flooding Hazard Reevaluations and Mitigating Strategies for Beyond Design Basis External Events, September 1, 2015 (ML15174A257)

3. Entergy's Required Response of the Near-Term Task Force Recommendation 2.1:

Flooding-Hazard Reevaluation Report, March 12, 2015 (ML15075A082)

4. NEI 12-06 (Rev. 1) - Diverse and Flexible Coping Strategies (FLEX) Implementation Guide, October 2015

Dear Sir or Madam:

The purpose of this letter is to inform the U.S. Nuclear Regulatory Commission (NRC) Staff of commitment changes, as well as to request deferral of actions related to Beyond-Design-Basis External Events (BDBEE) flooding actions for Pilgrim Nuclear Power Station (PNPS).

In Reference 1, PNPS provided notification to the NRC that the plant would cease operation in 2019. In light of the decision to permanently shut down and defuel, activities planned between now and the 2019 shutdown were 'reviewed. One of the activities scheduled during this period was the performance of the Mitigating Strategies Assessment (MSA) for flooding to meet the evaluation request documented in Reference 2.

Entergy Nuclear Operations, Inc. Letter No. 2.16.047 Pilgrim Nuclear Power Station Page 2 of 3 PNPS no longer considers the performance of the MSA commitment to be necessary given the flooding reevaluation report (Reference 3) found limited impact for the site on the reevaluated flooding hazard. Walkdowns have confirmed that inundation associated with the Local Intense Precipitation or the combined effect flood will not impact Systems, Structures and Components important to safety.

Additionally, although no actions or procedures are credited for flooding protection, the plant's procedure for operation during severe weather (i.e., PNPS Procedure 2.1.42, Operation During Severe Weather) includes measures that can be used for mitigating external flood conditions (e.g., ensuring that exterior doors are closed, installing sandbags at door bottoms and drain scuppers).

As noted in Nuclear Energy Institute 12-06, Revision 1, Appendix G (Reference 4): For some scenarios it may be more effective (e.g., require less resources, simpler to implement, more reliable, result in overall improvement in flood protection, etc.) to address the impacts of the Mitigating Strategies Flood Hazard Information (reevaluated flood hazard information) through the development of an Alternate Mitigating Strategy (AMS) as opposed to modifying the FLEX strategies.

The AMS would be based on a sequence of events determined from using the flood as the initiating event. The AMS would not assume an Extended Loss of Alternating Current) (ELAP) and Loss of Ultimate Heat Sink (LUHS) unless or until such time as the flood event caused such consequences.

As noted in Reference 3, PNPS has already determined that the new flooding hazard does not result.in an ELAP and LUHS events and that the current design bases adequately addresses the new flooding event indicating the current design bases provides the needed level of safety.

Additionally it is noteworthy, from a safety perspective, the conditions resulting in the limited impact documented in Reference 1 for Probable Maximum Precipitation water depths along the power block buildings are based on one-hour precipitation rates having a probability of occurrence of 1 x 10-5 per year.

Several other factors were also considered in the determination that the MSA commitment is not warranted for PNPS. The evaluation of the current FLEX strategy against the reevaluated flood hazard, design of required modifications, and implementation of the modifications would take time. The resultant actions would, at best, be implemented shortly before the final shutdown and more likely following final plant shutdown.

Therefore, no additional flood mitigating actions are planned and the current commitment is hereby being withdrawn.

Additionally, PNPS is informing the NRG that, in light of Reference 2, the decision to permanently shut down and defuel, flooding activities being performed to meet the NRG 10 Code of Federal Regulations 50.54(f) request for information and any related commitments planned between now and the 2019 Cessation of Power Operations are requested to be deferred.

Entergy Nuclear Operations, Inc. Letter No. 2.16.047 Pilgrim Nuclear Power Station Page 3 of 3 With the limited operating time left, there is insufficient time to complete evaluations, design and approve changes to the plant, and then implement those changes such that a meaningful improvement to safety is achieved prior to the defueling of the plant.

If you have any questions or require additional information, please contact Everett P. Perkins, Jr. at (508) 830-8323.

There are no regulatory commitments contained in this letter.

Sincerely, nA.Dent,~

ite Vice President JAD/rb cc: Mr. Daniel H. Dorman Regional Administrator, Region I U.S. Nuclear Regulatory Commission 2100 Renaissance Boulevard, Suite 100 King of Prussia, PA 19406-2713 Ms. Booma Venkataraman, Project Manager Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 0-8C2A Washington, DC 20555 Office of Nuclear Reactor Regulation Japan Lessons Learned Division U.S. Nuclear Regulatory Commission Mail Stop 13 C5 Washington, DC 20555 NRC Senior Resident Inspector Pilgrim Nuclear Power Station