GNRO-2012/00027, Responses to NRC Requests for Additional Information Pertaining to License Amendment Request for Criticality Safety Analysis

Responses to NRC Requests for Additional Information Pertaining to License Amendment Request for Criticality Safety Analysis

ML12109A281
Person / Time
Site:	Grand Gulf
Issue date:	04/18/2012
From:	Krupa M Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GNRO-2012/00027
Download: ML12109A281 (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-2012/00027 April 18, 2012 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

SUBJECT:

Responses to NRC Requests for Additional Information Pertaining to License Amendment Request for Criticality Safety Analysis Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 License No. NPF-29

REFERENCES:

1. Entergy Operations, Inc. letter to the NRC (GNRO-2011/00076),

License Amendment Request - Criticality Safety Analysis and Technical Specification 4.3.1, Criticality, September 9, 2011 (ADAMS Accession No. ML1125321287)

2. NRC e-mail to Entergy Operations, Inc., CSA LAR, March 21, 2012

Dear Sir or Madam:

In Reference 1, Entergy Operations, Inc. (Entergy) submitted to the NRC a license amendment request (LAR), which proposes to: 1) revise the criticality safety analysis (CSA) for the spent fuel and new fuel storage racks; 2) impose additional requirements for the spent fuel and new fuel storage racks in TS 4.3.1, Criticality; and 3) delete the spent fuel pool loading criteria Operating License Condition.

In Reference 2, the NRC transmitted to Entergy three requests for additional information (RAIs) pertaining to the CSA LAR. Responses to these RAIs are provided in the attachment to this letter.

This letter contains no new commitments.

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

GNRO-2012/00027 Page 2 of 2 I declare under penalty of perjury that the foregoing is true and correct; executed on April 18, 2012.

Sincerely, MAK/FGB/ghd Attachments: 1. Responses to NRC Requests for Additional Information Pertaining to License Amendment Request - Criticality Safety Analysis

2. NETCO Potential 10 CFR Part 21 Notification 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-2012/00027 Grand Gulf Nuclear Station Extended Power Uprate Responses to NRC Requests for Additional Information Pertaining to License Amendment Request - Criticality Safety Analysis to GNRO-2012/00027 Page 1 of 2 Responses to NRC Requests for Additional Information Pertaining to License Amendment Request - Criticality Safety Analysis Entergy Operations, Inc. (Entergy) submitted to the NRC a license amendment request (LAR),

which proposes to: 1) revise the criticality safety analysis (CSA) for the spent fuel and new fuel storage racks; 2) impose additional requirements for the spent fuel and new fuel storage racks in TS 4.3.1, Criticality; and 3) delete the spent fuel pool loading criteria Operating License Condition.

In an e-mail dated March 21, 2012, the NRC transmitted to Entergy three requests for additional information (RAIs) pertaining to the CSA LAR. Responses to these RAIs are provided below.

RAI #1 In the GGNS response letter dated November 21, 2011, RAI 3, the licensee stated that in 2010, NETCO identified a latent software error that incorrectly incorporated the drift correction factor into the areal density calculations for each analyzed panel in a BADGER campaign. In order for the staff to have reasonable assurance that the BADGER tool will provide pertinent and informative data to inform the licensee about the state of degradation of Boraflex in the SFP, the staff requests additional information about the data processing error and steps taken to address this error.

a) Please provide the initial correspondence letter NETCO provided to GGNS identifying this issue.

b) Please discuss the summary of actions taken by GGNS as a result of this error.

Response

On July 22, 2010, NETCO issued a potential 10 CFR Part 21 notification (see Attachment 2).

The NETCO error notification was entered into the GGNS Corrective Action Process for operability and reportability considerations. The revised areal densities reported by NETCO decreased when the error was corrected. The escape coefficients used in the GGNS Racklife calculation were then adjusted to better conform the updated Racklife predicted boron loss to the BADGER test results. These increased escape coefficients continue to be used for the current Racklife predictions. An evaluation was then completed to show that the reactivity margin between the Design Basis Bundle in the Analysis of Record and the actual fuel stored in the Spent Fuel Pool more than offset the reactivity penalty associated with the reduced areal density and the racks still maintained Keff 0.95 for the stored fuel.

A new CSA, which also considers the updated boron loss data, has been prepared. That CSA is the subject of the CSA LAR.

RAI # 2 The staff understands that GGNS has an upper containment spent fuel pool that credits Boraflex in maintaining subcriticality. Discuss whether the upper containment pool is included in the Boraflex Monitoring Program. Also, please discuss in detail the surveillance approach that will be used in monitoring this material in the upper containment pool, specifically the methods to GNRO-2012/00027 Page 2 of 2 of neutron attenuation testing (i.e., in-situ testing), frequency of inspection, sample size, data collection, and acceptance criteria.

Response

Racklife calculations are also performed for the Boraflex storage racks located in the GGNS Upper Containment Pool. Since fuel assemblies are not stored in these racks during normal operation, their use is limited to short durations during refueling outages for the temporary storage of fuel assemblies. Thus, their accumulated doses and boron losses are well bounded by the racks in the spent fuel pool. As such, no neutron attenuation testing has been conducted on the racks in the Upper Containment Pool. Racklife predicted peak panel doses and boron losses for the Spent Fuel Pool and the Upper Containment Pool are given in Table 1, below, for 02/19/2012 (EOC18).

Table 1 Racklife Predicted Peak Panel Doses and Boron Loss for 02/19/2012 Peak Panel Dose Peak Panel Pool (Rad) Boron Loss (%)

Spent Fuel Pool 4.09E10 10.8 Upper Containment Pool 1.16E10 7.8 RAI #3 Provide the current number of usable storage racks for the upper containment and spent fuel pools.

Response

The Spent Fuel Pool contains 15 usable Boraflex storage racks while the Upper Containment Pool contains 7 usable Boraflex storage racks.

TS 4.3.3 allows the storage of up to 4348 assemblies in the spent fuel pool and 800 assemblies in the upper containment pool. There are racks to provide storage for up to 4348 assemblies in the spent fuel pool and up to 712 assemblies in the upper containment pool. Of the storage cells in the spent fuel pool, there are currently 126 cells designated as Region II cells and the balance (4222 cells) are Region 1 cells. All of the storage cells in the upper containment pool are considered to be usable.

GGNS has restricted fuel storage in some of the racks for reasons other than reactivity control.

The restrictions may be due to access limitations, load restrictions or dose restrictions; these are generally still considered to be usable locations. A total of 717 cells are restricted in the Region 1 racks in the spent fuel pool and 126 are restricted in the upper containment pool.

Attachment 2 GNRO-2012/00027 NETCO Potential 10 CFR Part 21 Notification

Notice of Inability to Evaluate Possible 10CFR21 Implications RE: Decrease in average BADGER measured Boraflex B10 areal density/Grand Gulf.

Date: 7/22/10 NOTE: Please acknowledge receipt to NETCO QA Manager as soon as possible (LMariani@curtisswright.com).

Recent improvements in the method used to calibrate BADGER equipment lead to the discovery that a correction factor used to account for physical differences between the un-attenuated region of the reference panel fuel cell and each of the other fuel cells subjected to BADGER measurement may not, in all instances, have provided conservative results. As a consequence in some cases, the corrected value of the average measured Boraflex areal density has been seen to decrease.

In connection with the most recent BADGER campaign conducted at Grand Gulf Nuclear Station, NETCO reported in NET-287-01, BADGER TEST CAMPAIGN AT GRAND GULF NUCKEAR STATION, 2/8/08, that the average areal density for all panels measured was 0.0207 +/- 0.0016 grams of B10 per cm2. Re-evaluation of the average measured areal density has provided a revised value for the average measured areal density of 0.0185 +/- 0.0020 grams of B10 per cm2. During the Grand Gulf BADGER campaign 32 Boraflex panels were tested. The spent fuel pool contains 4393 fuel cells.

For these panels, the average measured areal density has decreased by approximately 10.6 percent below the previously reported value. Further, the minimum value of measured areal density reported in NET-287-01 was 0.0170 grams of B10 per cm2. The recalculated value was determined to be 0.0157 gram of B10 per cm2. Thus the minimum measured value of areal density decreased by 7.6 percent.

Depending upon how these results are used in connection with the Grand Gulf criticality analysis of record for the spent fuel pool, there may be an associated decrease in margin to the Keff < 0.95 limit. In that NETCO is not able to evaluate the impact of these revisions on criticality margin and is therefore unable to evaluate possible 10CFR21 implications, these results are provided for your consideration and possible evaluation of 10CFR21 implications.

The date of discovery of these modified values of measured areal density was made on July 22, 2010. In the event that you require further information please do not hesitate to contact NETCO.

Sincerely, Matthew C. Harris, NETCO BADGER Test Engineer cc. Matthew Eyre, Director, NETCO Leo Mariani, QA Manager, NETCO