ML15050A245

Response to Request for Supplemental Information Needed for Acceptance of Requested Licensing Action Regarding the Safety Limit Minimum Critical Power Ratio License Amendment Request

ML15050A245
Person / Time
Site:	Pilgrim
Issue date:	02/13/2015
From:	Dent J Entergy Nuclear Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
2.15. 015, TAC MF5431
Download: ML15050A245 (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 February 13, 2015 U.S, Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

SUBJECT:

Response to Request for Supplemental Information Needed For Acceptance of Requested Licensing Action Regarding the Safety Limit Minimum Critical Power Ratio License Amendment Request (TAC NO.

MF5431)

Entergy Nuclear Operations, Inc.

Pilgrim Nuclear Power Station Docket No. 50-293 License No. DPR-35

REFERENCES:

1. Entergy Letter to NRC, "Proposed Change to Pilgrim Technical Specifications Concerning the Safety Limit Minimum Critical Power Ratio", dated December 10, 2014 (2.14.076)

2. NRC Letter to Entergy, "Pilgrim Nuclear Power Station -

Supplemental Information Needed For Acceptance of Requested Licensing Action Regarding the Safety Limit Minimum Critical Power Ratio License Amendment Request (TAC NO. MF5431)", dated February 3, 2015 LETTER NUMBER: 2.15. 015

Dear Sir or Madam:

In Reference 1, Entergy proposed to amend Facility Operating License DPR-35 for the Pilgrim Nuclear Power Station (PNPS) by modifying Technical Specification Section 2.1.2. The application proposed to change the Safety Limit Minimum Critical Power Ratio (SLMCPR) in Technical Specification (TS) Section 2.1.2 from > 1.08 to > 1.1 0 for two recirculation loop operation and from Ž 1.11 to Ž_ 1.12 for single loop operation.

In Reference 2, the Nuclear Regulatory Commission (NRC) staff requested that Entergy provide the regulatory criteria used to determine that the license amendment request (LAR) is acceptable.

Entergy Nuclear Operations, Inc. Letter Number: 2.15.015 Pilgrim Nuclear Power Station Page 2 of 3 The applicable regulatory requirements and criteria are:

10 CFR 50.36, "Technical specifications", requires safety limits upon important process variables that are found to be necessary to reasonably protect the integrity of certain of the physical barriers that guard against the uncontrolled release of radioactivity. In this instance, the Safety Limit Minimum Critical Power Ratio (SLMCPR) ensures the integrity of the fuel cladding during normal and abnormal operations and to mitigate the transient and accident conditions.

10 CFR 50, Appendix A, GDC 10, "Reactor design" states "The reactor core and associated coolant, control, and protection systems shall be designed with appropriate margin to assure that specified acceptable fuel design limits are not exceeded during any condition of normal operation, including the effects of anticipated operational occurrences."

Fuel design limits can be exceeded ifthe core exceeds critical power. Critical power is a term used for the power at which the fuel departs from nucleate boiling and enters a transition to film boiling. For boiling water reactors (BWRs), the critical power is predicted using a correlation known as the GE (General Electric) critical quality boiling length correlation, or better known as the GEXL correlation. Due to core wide and operational variations, the margin to boiling transition is most easily described in terms of a critical power ratio (CPR), which is defined as the rod critical power as calculated by GEXL divided by the actual rod power. The more a CPR value exceeds 1.0, the greater the margin to boiling transition. The SLMCPR is calculated using a statistical process that takes into account operating parameters and uncertainties. The operating limit MCPR (OLMCPR) is equal to the SLMCPR plus a CPR margin for transients. At the OLMCPR, at least 99.9 percent of the rods avoid boiling transition during steady state operation and transients caused by a single operator error or equipment malfunction.

The proposed increase in the SLMCPR in PNPS TS Section 2.1.2 follows the requirements above and ensures the integrity of the fuel cladding.

This submittal contains no new regulatory commitments.

If you have questions regarding this subject, please feel free to contact Everett P.

Perkins at (508) 830-8323.

I declare under the penalty of perjury that the foregoing information is true and correct.

Executed on the 13th day of February, 2015 Sincerely, John A. Dent, Jr.

Site Vice President JAD/mew

Entergy Nuclear Operations, Inc. Letter Number: 2.15.015 Pilgrim Nuclear Power Station Page 3 of 3 cc:

U.S. Nuclear Regulatory Commission Mr. John Priest, Director ATTN: Dan Dorman Massachusetts Department of Public Health Regional Administrator, Region 1 Schraft Center Suite 1 M2A 2100 Renaissance Blvd, Suite 100 Radiation Control Program King of Prussia, PA 19406-2713 529 Main Street Charlestown, MA 02129 Ms. Nadiyah Morgan, Project Manager Mr. John Giarrusso, Jr.

Division of Operating Reactor Licensing Nuclear Preparedness Manager Office of Nuclear Reactor Regulation Mass. Emergency Management Agency U.S. Nuclear Regulatory Commission 400 Worcester Road One White Flint North O-8F4 Framingham, MA 01702 11555 Rockville Pike Rockville, MD 20852 NRC Senior Resident Inspector Pilgrim Nuclear Power Station Plymouth, MA 02360