GNRO-2012/00151, Boron-10 Areal Density Gage for Evaluating Racks (BADGER) Testing

Boron-10 Areal Density Gage for Evaluating Racks (BADGER) Testing

ML12353A598
Person / Time
Site:	Grand Gulf
Issue date:	12/17/2012
From:	Mike Perito Entergy Operations
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
GNRO-2012/00151
Download: ML12353A598 (8)

Text

~Entergy GNRO-2012/00151 December 17, 2012 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Entergy Operations, Inc.

P. o. Box 756 Port Gibson, MS 39150 Michael Perito Vice President, Operations Grand Gulf Nuclear Station Tel. (601) 437-6409

Dear Sir or Madam:

Boron-10 Areal Density Gage for Evaluating Racks (BADGER) Testing Grand Gulf Nuclear Station, Unit No. 1 Docket No. 50-416 License No. NPF-29 Grand Gulf Nuclear Station - Response to Request for Additional Information Regarding Extended Power Uprate dated May 3,2011 (GNRO-2011/00034)

On May 3, 2011, Grand Gulf Nuclear Station (GGNS) submitted in the referenced letter, a response to a request for additional information (RAI). In the response, GGNS committed to performing periodic surveillances of the Boraflex neutron absorbing material at least every five years using Boron-10 Areal Density Gage for Evaluating Racks (BADGER) testing. Additionally, the first test campaign was to be completed by December 31,2012. Due to the need to improve reliability and accuracy of the equipment as described in attachment 1 to this letter and the testing schedule estimate in attachment 2, GGNS must defer the completion date for the first test campaign to December 31,2013. Attachment 3 contains the revised completion date for this commitment.

This letter revises the commitment due date for one commitment. If you have any questions or require additional information, please contact Jeffery Alan Seiter at 601-437-2344.

This commitment supersedes the commitment made by the referenced Entergy letter to the NRC dated May 3, 2011.

I declare under penalty of perjury that the foregoing is true and correct. Executed on December 17,2012.

Sincerely,

~

Attachments and cc: (see next page)

GNRO-2012/00151 Page 2 of 2 Attachments:

1 Boron-10 Areal Density Gage for Evaluating Racks (BADGER) Testing Deferral Justification 2

Badger Testing Schedule Estimate 3

List of Regulatory Commitments cc: with Attachments U.S. Nuclear Regulatory Commission ATIN: Mr. Elmo E. Collins, Jr. (w/2)

Region Administrator, Region IV 1600 East Lamar Boulevard Arlington, TX 76011-4511 U. S. Nuclear Regulatory Commission ATIN: Mr. Alan Wang, NRRlDORL (w/2)

Mail Stop OWFN 8 B1 Washington, DC 20555-0001 NRC Senior Resident Inspector Grand Gulf Nuclear Station Port Gibson, MS 39150 to GNRO-2012/00151 Boron-10 Areal Density Gage for Evaluating Racks (BADGER) Testing Deferral Justification

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~FlowControl Company NETCO November 29,2012 Robert Carroll Entergy Nuclear Operations Grand Gulf Nuclear Station 7003 Bald Hill Road Port Gibson, MS 39150

Dear Mr. Carroll:

NETCO 731 Grant Avenue Lake Katrine. NY 12449 Phone 845,382.6900 http://netco,cwfc.com As you are aware, unsuccessful prototype testing of the redesigned BADGER system in October at Penn State prevented deployment of the system at Grand Gulf in 2012.

As you are likely not as familiar with the BADGER system, it may not be readily apparent why the BADGER redesign is taking place at all. As such, I wanted to give you a bit of insight as to why the activities are currently being undertaken and hence, the reasons for the current delays in BADGER testing.

BADGER 2.0 Prototype Testing Following the BADGER testing campaigns at Millstone 1 in June 2011 and Oyster Creek in October and December 2011, NETCO has initiated a corrective action to improve the design and reliability of the BADGER testing system.

The impetus for this redesign is driven by two basic needs: 1) to improve the reliability of the BADGER data collection system components and 2) improve the accuracy and uncertainty of the BADGER measurements. BADGER testing was originally developed in 1995 for the Electric Power Research Institute to merely be a "management toor' used for monitoring the trend of Boraflex degradation and estimate the useful service life of Boraflex spent fuel racks. The BADGER system was not intended to be a determinant of whether or not,racks were satisfying a tech spec requirement. Many uncertainties, inherent in performing neutron attenuation measurements in an aqueous (spent fuel pool) environment remain in the BADGER system. Some of these uncertainties are uncontrollable, while others are a relic of counting neutron pulses in a non-idealized configuration with a point source. Previous measurements in spent fuel pools have resulted in somewhat large measurement uncertainties because of the limitations of performing neutron attenuation measurements in a geometrically confined space. While perhaps acceptable for spent fuel rack monitoring purposes, these large measurement uncertainties included in a criticality analysis, reduce the margin to the keff < 0.95 limit, prompting the need to improve the accuracy of the BADGER measurements.

Page 2 of 2 neutron areas where the BADGER head designed can be optimized. This has resulted in numerous design modifications to the BADGER heads in order to improve the measurement uncertainty, as well as improvements in the overall detector circuitry in an attempt to eliminate electrical The implementation these design changes was contingent on the demonstration in a clean pool test at the Cobalt-BO facility Radiation and Engineering Center.

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modifications implemented were not successful, as the neutron signals were renaolre to an level by neutron will you the nrn,nroc:-c:o will put BADGER testing when we can firm schedule to GNRO*2012/00151 Badger Testing Schedule Estimate

NETCO 731 Grant Avenue Lake Katrine, NY 12449 Phone 845.382.6900 http://netco.cwfc.com December 11, 2012 Robert Carroll Entergy Nuclear Operations Grand Gulf Nuclear Station 7003 Bald Hill Road Port Gibson, MS 39150

Dear Mr. Carroll:

Based on our schedule estimates to complete the BADGER redesign and prototype testing, we anticipate being able to complete a BADGER test at Grand Gulf in early to mid-3rd Quarter of 2013.

Sincerely, I

Matt Harris Principal Engineer/Radiation Safety Officer NETCO, a business unit of Curtiss-Wright Flow Control Company to GNRO-2012/00151 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.

COMMITMENT TYPE (Check One)

SCHEDULED I-----,..---------j COMPLETION ONE-DATE TIME CONTINUING (If Required)

ACTION COMPLIANCE Grand Gulf Nuclear Station (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 31,2013.

The following test approach, which was described in response to RAI # 2 in Entergy's 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 Criticality Safety Analysis (CSA) of Spent and New Fuel Storage Racks 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 GSA distributions bound the corresponding Badger measured distributions.

Alternatively, the measured gap distributions are acceptable jf the GSA 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-33621 P, 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>>. RAGKLlFE 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 RAGKLIFE analysis date to ensure current Region I storage locations will not need to be reclassified as Region I!

storage locations in the analysis interval.

x December 31, 2013