GNRO-2011/00089, Response to NRC Request for Additional Information Pertaining to License Amendment Request for Power Range Neutron Monitoring System

Response to NRC Request for Additional Information Pertaining to License Amendment Request for Power Range Neutron Monitoring System

ML112911553
Person / Time
Site:	Grand Gulf
Issue date:	10/18/2011
From:	Krupa M Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GNRO-2011/00089, TAC ME2531
Download: ML112911553 (4)

Text

Entergy Operations, Inc.

P. O. Box 756 Port Gibson, MS 39150 Michael A. Krupa Director, Extended Power Uprate Grand Gulf Nuclear Station Tel. (601) 437-6694 GNRO-2011/00089 October 18, 2011 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555

SUBJECT:

Response to NRC Request for Additional Information Pertaining to License Amendment Request for Power Range Neutron Monitoring System (TAC No. ME2531)

Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 License No. NPF-29

REFERENCES:

1. Entergy Operations, Inc. letter to the NRC (GNRO-2009/00054),

License Amendment Request Power Range Neutron Monitoring System Upgrade, November 3, 2009 (ADAMS Accession No. ML093140463)

2. Entergy Operations, Inc. letter to the NRC (GNRO-2011/00042),

Responses to NRC Requests for Additional Information Pertaining to License Amendment Request for Power Range Neutron Monitoring System (TAC No. ME2531), May 31, 2011 (ADAMS Accession No. ML111520123)

Dear Sir or Madam:

In Reference 1, Entergy Operations, Inc. (Entergy) submitted to the NRC a license amendment request (LAR), which proposes to revise the Grand Gulf Nuclear Station (GGNS)

Technical Specifications (TS) to reflect installing the digital General Electric-Hitachi (GEH)

Nuclear Measurement Analysis and Control (NUMAC) Power Range Neutron Monitoring (PRNM) System.

In Reference 2, Entergy submitted to the NRC responses to several Requests for Additional Information (RAIs) to support the staff s review and approval of Reference 1. In a telephone conversation held on October 12, 2011, Entergy discussed with the NRC Project Manager for GGNS an error discovered in the response to RAI 24, which was included in Attachment 1 of Reference 2. Specifically, a statement provided in the response to RAI 24 incorrectly denoted the reactor power level at which the Oscillation Power Range Monitor (OPRM) is enabled at GGNS to be 24%. The correct level is 29%.

GNRO-2011/00089 Page 2 of 2 Entergy is providing a corrected, revised page of the response in Attachment 1. The change is indicated by a revision bar in the margin of the replacement page. This page replaces the page of the original response. Note the page number in Attachment 1 is consistent with the page number in Attachment 1 of Reference 2.

The No Significance Hazards Determination and the Environmental Consideration provided in Reference 1 are not impacted by any information contained in this letter.

This letter contains no new commitments.

If you have any questions or require additional information, please contact Mr. Guy Davant at (601) 368-5756.

I declare under penalty of perjury that the foregoing is true and correct; executed on October 18, 2011.

Sincerely, MAK/ghd

Attachment:

Changed Page to the Response to NRC RAI 24 Pertaining to License Amendment Request for the Power Range Neutron Monitoring System Upgrade cc: Mr. Elmo E. Collins, Jr.

Regional Administrator, Region IV U. S. Nuclear Regulatory Commission 612 East Lamar Blvd., Suite 400 Arlington, TX 76011-4005 U. S. Nuclear Regulatory Commission ATTN: Mr. A. B. Wang, NRR/DORL (w/2)

ATTN: ADDRESSEE ONLY ATTN: Courier Delivery Only Mail Stop OWFN/8 B1 11555 Rockville Pike Rockville, MD 20852-2378 State Health Officer Mississippi Department of Health P. O. Box 1700 Jackson, MS 39215-1700 NRC Senior Resident Inspector Grand Gulf Nuclear Station Port Gibson, MS 39150

ATTACHMENT GRAND GULF NUCLEAR STATION GNRO-2011/00089 CHANGED PAGE TO THE RESPONSE TO NRC RAI 24 PERTAINING TO LICENSE AMENDMENT REQUEST FOR THE POWER RANGE NEUTRON MONITORING SYSTEM UPGRADE Notes The page number specified in this attachment is consistent with the page number in Attachment 1 of the original RAI response submittal (NRC ADAMS Accession No. ML1111520123).

The original page of the RAI response was marked GEH Proprietary ; however, this replacement page contains no such information.

Revised Page 71 of 101 The OPRM is a sub-system within PRNMS for stability monitoring and mitigation, which is enabled above a predetermined power level (29% for GGNS). OPRM trip setpoints correspond to a pre-determined number of confirmed oscillations and pre-determined oscillation amplitude, and are not calculated by GEH setpoint methodology. These OPRM setpoints do not have ALs, AVs, and NTSPs with margins based on instrument error and GEH setpoint methodology. This was explained in the response to RAI 10 of Reference 2.

The following information is excerpted from that response:

The OPRM setpoints are nominal setpoints, which are established using a comprehensive BWR Owners Group (BWROG) methodology for stability analysis approved by the NRC.

There is no AL or AV with defined instrument error margins to the NTSP for the OPRM setpoints. Note that OPRM setpoints are not considered to be Limiting Safety System Settings (LSSSs) since stability is a special event, and not an Anticipated Operational Occurrence (AOO), which defines LSSSs.

These OPRM setpoints are established as nominal values based on cycle specific reload stability analysis and are included in the Core Operating Limits Report (COLR).

Use of nominal setpoints for the OPRM Upscale function has been addressed during the licensing of PRNMS at Browns Ferry Unit 1 and at Monticello, previously. Note also that the OPRM trip setpoints are not listed in the BWR/6 Standard Technical Specifications.

Demonstration calculations for the nominal setpoints of the OPRM Upscale function are available for review. They may be viewed by the NRC at a GEH office, upon request.

The power level at which OPRM is enabled is also a nominal setpoint determined by stability methodology and not by GEH setpoint methodology. This enabling setpoint is considered a permissive and is not annotated in TSTF-493.

(d) How the performance data is used to establish the final setpoint, and as-left and as-found tolerances Setpoint Calculations The PRNM setpoints are calculated as described in the General Description section, above, using errors specified in the PRNM specifications as described Section (a), above. The specified PRNM errors are conservative and have high confidence (95%). Thus, the PRNM setpoint calculations based on specified PRNM errors and the approved GEH setpoint methodology meet the RG 1.105 95/95 requirements for AL/NTSPF margin. Specifically, since NTSP1 (LTSP) has the required margin to the AL to meet RG 1.105 requirements and since NTSPF is equal or more conservative than NTSP1, it also meets RG 1.105 requirements.

The equations for calculating the setpoints (AV, NTSP1, and NTSPF) and relevant explanations are given in the response to RAI 10 of Reference 2. In that response, the final setpoint is referred to as NTSP(Adj) whereas in this response it is referred to as NTSPF for clarity. Because NTSP1 (LTSP) meets the RG 1.105 requirements and NTSPF is generally more and never less conservative than NTSP1, it also meets RG 1.105 requirements. As an example, according to GEH methodology, the AL/NTSP1 margin is the algebraic addition of the bias errors plus a random error margin equal to 1.645

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