ML15090A139

Request for Additional Information Regarding Fluence License Amendment Request

ML15090A139
Person / Time
Site:	Grand Gulf
Issue date:	03/30/2015
From:	Wang A Plant Licensing Branch IV
To:	Scarbrough R Entergy Nuclear Operations
References
TAC MF5303
Download: ML15090A139 (3)

Text

1 NRR-PMDAPEm Resource From: Wang, Alan Sent: Monday, March 30, 2015 4:24 PM To: 'SCARBROUGH, RICHARD A (RSCARBR

@entergy.com)'; 'Nadeau, James' Cc: Blechman, Paula

Subject:

Grand Gulf Nuclear Station, Unit 1, Request for Additional Information Regarding Fluence License Amendment Request (TAC No. MF5303)

Jeff and Jim, by letter dated November 21, 2014 (Agencywide Document Access and Management System (ADAMS) Accession No. ML14325A752), Entergy Operations, Inc. (Entergy, the licensee), submitted a license amendment request for the Grand Gulf Nuclear Stati on, Unit No. 1 (GGNS). The proposed amendment would revise it s licensing basis to adopt a single fluence methodology. By letter dated February 18, 2015 (ADAMS Accession No. ML15036A564), the US Nuclear Regulatory Commission (NRC) staff provided the results of the staff's acceptance revi ew of this amendment request and requested supplemental information. Ente rgy responded to this request by letter dated February 18, 2015 (ADAMS Accession No.

M L15049A536). The NRC sta ff has reviewed the licensee's February 18, 2015, submittal for regar ding the fluence methodology and has determined that the following additional informati on is required to complete its re view of the amendment request.

RAI 1 Confirm that fluence corrections are applied appropriately (i.e. considering bias and uncertainty) for all calculated fluence results that exceed 20%. The supplementary information provided in the licensee's response dated February 8, 2015, to the ac ceptance review RAI 1b indicates that only calculated fluence results with uncertainties greater than 30% are appropriately treated; it is not stated how calculated fluence results with uncer tainties between 20% and 30% are treated, if uncertainties in this range exist.

RAI 2 The fluence uncertainties for upper regions of the reactor vessel are highly sensitive to the assumed above core void fraction distribution. What analysis has been performed in support of the assumed void fraction in the region above the core including consideration of the MELLLA+ operating domain?

RAI 3 What is the potential for the high uncertainty outside-of-beltline reactor pressure vessel regions to be limiting with respect to pressure/temperature curve generation over the ent ire period of extended operation?

RAI 4 In GNRO-2015/00011, Attachment 1, it is stated that "this letter contains no new commitments." However, the response to RAI 1a in the same document states:

Installing dosimetry capsules and/or taking scrapings in specified areas out side of the beltline region would provide dosimetry data for a fu ture benchmark analysis outside of the beltline region. The uncertainty in the fluence calculations at locations above the top of the core is dominated by uncertainty in the water density. Taking scrapings and/or inserting dosimetry in 2 these locations (during future refueling out ages) would not only provide benchmarking data, but it would also provide t he data needed to check the output fr om thermal hydraulics codes that can be used in future improvements of the upper region wa ter density modeling.

The NRC staff request that Entergy provide a regulat ory commitment to install dosimetry capsules and/or scrapings, to qualify the 3D fluence method fo r fluence calculations ou tside of the beltline region. Provide details regarding the plans and schedule for installing dosimetry capsules and/or scrapings including the proposed locations for dosimetry capsule installation.

Also, provide a regulatory commitm ent to confirm that future ca lculated-to-measured (C/M) fluence values at the dosimetry location(s) are reasonably close to one in cluding explicit definition of "reasonably close to one" (e.g. C/M greater t han 0.8) and plans to address any substantial disagreements.

This RAI was discussed with Mr. Richard Scarbrough on March 30 , 2015, and it was agreed that a response would be provided within 30 days of receipt of this email. If circumstances result in the need to revise the requested response date, please c ontact me at (301) 415-1445 or via e-mail at Alan.Wang@nrc.gov.

Alan Wang Project Manager (Grand Gulf Nuclear Station) Nuclear Regulatory Commission Division of Operating Reactor Licensing Alan.Wang@NRC.gov Tel: (301) 415-1445

Fax: (301) 415-1222

Hearing Identifier: NRR_PMDA Email Number: 1959 Mail Envelope Properties (C0A338EE37A11447B136119705BF9A3F02881272B920)

Subject:

Grand Gulf Nuclear Station, Unit 1, Request for Additional Information Regarding Fluence License Amendment Request (TAC No. MF5303) Sent Date: 3/30/2015 4:24:18 PM Received Date: 3/30/2015 4:24:00 PM From: Wang, Alan Created By: Alan.Wang@nrc.gov Recipients: "Blechman, Paula" <Paula.Blechman@nrc.gov> Tracking Status: None

"'SCARBROUGH, RICHARD A (RSCARBR@entergy.com)'" <RSCARBR@entergy.com> Tracking Status: None "'Nadeau, James'" <jnadea1@entergy.com>

Tracking Status: None Post Office: HQCLSTR02.nrc.gov

Files Size Date & Time MESSAGE 4201 3/30/2015 4:24:00 PM

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