GNRO-2011/00034, Request for Additional Information Regarding Extended Power Uprate

Request for Additional Information Regarding Extended Power Uprate

ML111240288
Person / Time
Site:	Grand Gulf
Issue date:	05/03/2011
From:	Krupa M Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GNRO-2011/00034
Download: ML111240288 (8)

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) 437-6684 GNRO-2011/00034 May 3, 2011 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

SUBJECT:

Request for Additional Information Regarding Extended Power Uprate Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 License No. NPF-29

REFERENCES:

1. Email from A. Wang to F. Burford dated April 4, 2011, GG EPU SG and Chemical Engineering Branch Request for Additional Information (M4679) (Accession Number ML110940136)

2. License Amendment Request, Extended Power Uprate, dated September 8, 2010 (GNRO-2010/00056, Accession Number ML102660403)

Dear Sir or Madam:

The Nuclear Regulatory Commission (NRC) requested additional information (Reference 1) regarding certain aspects of the Grand Gulf Nuclear Station, Unit 1 (GGNS) Extended Power Uprate (EPU) License Amendment Request (LAR) (Reference 2). Attachment 1 provides responses to the additional information requested by the Steam Generator and Chemical Engineering Branch.

No change is needed to the no significant hazards consideration included in the initial LAR (Reference 2) as a result of the additional information provided. There are new commitments included in this letter.

If you have any questions or require additional information, please contact Jerry Burford at 601-368-5755.

GNRO-2011/00034 Page 2 of 2 I declare under penalty of perjury that the foregoing is true and correct. Executed on May 3, 2011.

Sincerely, MAK/FGB/dm Attachments:

1. Response to Request for Additional Information, Steam Generator and Chemical Engineering Branch

2. List of Regulatory Commitments 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 1 GNRO-2011/00034 Grand Gulf Nuclear Station Extended Power Uprate Response to Request for Additional Information Steam Generator and Chemical Engineering Branch to GNRO-2011/ 00034 Page 1 of 3 Response to Request for Additional Information Steam Generator and Chemical Engineering Branch By letter dated September 8, 2010, Entergy Operations, Inc. (Entergy) submitted a license amendment request (LAR) for an Extended Power Uprate (EPU) for Grand Gulf Nuclear Station, Unit 1 (GGNS) (ADAMS Accession Number ML102660403). By letter dated March 9, 2011 (GNRO-2011/00017, ADAMS Accession Number ML110680507) Entergy provided responses to the initial set of questions from the Steam Generator and Chemical Engineering Branch.

Subsequently, the U.S. Nuclear Regulatory Commission (NRC) staff has determined that the following additional information requested by the Steam Generator and Chemical Engineering Branch (ADAMS Accession Number ML110940136) is needed for the NRC staff to complete their review of the amendment. Entergys response to each item is also provided below.

RAI # 1 Based on industry operating experience, degradation of Boraflex panels occur in a much less uniform configuration than is shown in the spent fuel pool map provided in your letter dated March 9, 2011. That map shows that Region II racks (the racks that are degraded beyond a usable condition) are located together in the center of the pool. Please provide a map of the spent fuel pool which shows the cumulative dose to each panel in the pool. Also, discuss why Region II cells would be located in one specific area of the pool, and other cells outside of that area would not experience similar degradation after housing recently discharged fuel.

Response

A map of the GGNS spent fuel pool (SFP) is provided in Figure 1-1. As depicted in the legend, the cells that are red have a cumulative dose greater than or equal to 2.3 E10 rads; those that are yellow have a cumulative dose less than 2.3E10 rads and greater than or equal to 1.3E10 rads; those that are dark green have a cumulative dose less than 1.3E10 rads and greater than or equal to 5.9E09 rads; and those that are light blue have a cumulative dose less than 5.9E09 rads. As described in the March 9, 2011 response, Region II cells are those that have reached a cumulative dose of 2.3E10 rads.

Region II is a discrete area due to freshly discharged high dose rate fuel that was placed in the current Region II locations in support of the Blackness test campaigns. This fuel remained in these locations for approximately one year. These high dose fuel assemblies were replaced with freshly discharged fuel in subsequent cycles. Other areas of the pool have been typically loaded with a single assembly that has remained in that location. Since a large fraction of the dose emitted by a discharged fuel assembly occurs during the first year, the Region II area leads the balance of the pool. Recent SFP loading patterns have been established to distribute discharged fuel assemblies to minimize the cumulative dose to Region I Boraflex panels, thereby limiting the number of Boraflex panels that exceed the dose threshold of 2.3E10 rads.

to GNRO-2011/ 00034 Page 2 of 3 Figure 1-1 GGNS Spent Fuel Pool Boraflex Panel Cumulative Dose Distribution to GNRO-2011/ 00034 Page 3 of 3 RAI # 2 In your response letter dated March 9, 2011, it states, an additional BADGER [Boron-10 Areal Density Gauge for Evaluating Racks] measurement will be performed prior to the end of 2012.

The need for additional tests will be determined following the 2012 test campaign, based on the test results along with projected rack performance. The NRC staff believes that the data from the performance of a one-time BADGER campaign is insufficient to ensure that the Boraflex neutron absorber material will continue to perform its intended function.

a. Please provide the future (i.e., after 2012) surveillance approach and BADGER testing for the Boraflex material. The NRC staff has provided the details of one acceptable program for periodic surveillance of Boraflex neutron absorbing materials in the Generic Aging Lessons Learned, Rev 2, program XI.M22, Boraflex Monitoring.

Response

GGNS will perform periodic surveillances of the Boraflex neutron absorbing material at least every five years using Boron-10 Areal Density Gage for Evaluating Racks (BADGER) testing.

The first test campaign will be completed by December 31, 2012.

The following test approach, which was described in response to RAI # 2 in Entergys March 9, 2011 letter to the NRC, will be used. The tests will consist of at least 30 panels. The Badger to Racklife uncertainty will be developed from the test results. This value will be considered acceptable if it is less than the existing Badger/Racklife uncertainty. Additionally, the minimum Badger areal density results will be confirmed to be greater than the CSA assumption. The gap size and location probability distributions will also be compared to those used in the CSA. The acceptability of these parameters will be based on verifying that all of the CSA distributions bound the corresponding Badger measured distributions. Alternatively, the measured gap distributions are acceptable if the CSA calculations are repeated using the measured gap distributions and the resulting 95/95 k-effective is bounded by the corresponding CSA Region 1 result (see Table 1 of NEDC-33621P, Grand Gulf Nuclear Station Fuel Storage Criticality Safety Analysis of Spent and New Fuel Storage Racks, Attachment 2 to the November 23, 2010 letter (ADAMS Accession Number ML103330093)).

RACKLIFE analysis will continue to be performed each cycle. This analysis will include a comparison of the RACKLIFE predicted silica to the plant measured silica. This comparison will determine if adjustments to the RACKLIFE loss coefficient are merited. The analysis will include projections to the next planned RACKLIFE analysis date to ensure current Region I storage locations will not need to be reclassified as Region II storage locations in the analysis interval.

This commitment supersedes the commitments made by Entergy letter to the NRC dated March 9, 2011.

Attachment 2 GNRO-2011/00034 Grand Gulf Nuclear Station Extended Power Uprate List of Regulatory Commitments to GNRO- 2011/00034 Page 1 of 1 List of Regulatory Commitments The following table identifies those actions committed to by Entergy in this document. Any other statements in this submittal are provided for information purposes and are not considered to be regulatory commitments.

TYPE (Check one) SCHEDULED ONE- CONTINUING COMPLETION TIME COMPLIANCE DATE COMMITMENT (If Required)

ACTION GGNS will perform periodic surveillances of the Boraflex neutron absorbing material on at least a five year frequency using Boron-10 Areal Density Gage for Evaluating Racks (BADGER) testing. The first test campaign will be completed by December 31, 2012.

The tests will consist of at least 30 panels. The Badger to Racklife uncertainty will be developed from the test results. This value will be considered acceptable if it is less than the existing Badger/Racklife uncertainty.

Additionally, the minimum Badger areal density results will be confirmed to be greater than the CSA assumption.

The gap size and location probability distributions will also be compared to those used in the CSA. The acceptability of these parameters will be based on verifying that all of the CSA distributions bound the corresponding Badger measured distributions.

Alternatively, the measured gap distributions are acceptable if the CSA calculations are repeated using the x

measured gap distributions and the resulting 95/95 k-effective is bounded by the corresponding CSA Region 1 result (see Table 1 of NEDC-33621P, Grand Gulf Nuclear Station Fuel Storage Criticality Safety Analysis of Spent and New Fuel Storage Racks, to the November 23, 2010 letter (ADAMS Accession Number ML103330093)).

RACKLIFE analysis will continue to be performed each cycle. This analysis will include a comparison of the RACKLIFE predicted silica to the plant measured silica.

This comparison will determine if adjustments to the RACKLIFE loss coefficient are merited. The analysis will include projections to the next planned RACKLIFE analysis date to ensure current Region I storage locations will not need to be reclassified as Region II storage locations in the analysis interval.