ML16019A283

Request for Additional Information Related to License Amendment Request Regarding Extended Power Uprate

ML16019A283
Person / Time
Site:	Browns Ferry
Issue date:	01/28/2016
From:	Farideh Saba Plant Licensing Branch II
To:	James Shea Tennessee Valley Authority
Saba F
References
CAC MF4851, CAC MF4852, CAC MF4853
Download: ML16019A283 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 January 28, 2016 Mr. Joseph W. Shea Vice President, Nuclear Licensing Tennessee Valley Authority 1101 Market Street, LP 3R-C Chattanooga, TN 37402-2801

SUBJECT:

BROWNS FERRY NUCLEAR PLANT, UNITS 1, 2, AND 3 - REQUEST FOR ADDITIONAL INFORMATION RELATED TO LICENSE AMENDMENT REQUEST REGARDING EXTENDED POWER UPRATE (CAC NOS. MF4851, MF4582, AND MF4853)

Dear Mr. Shea:

By letter dated September 21, 2015 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15282A152), as supplemented by letters dated November 13, December 15, and December 18, 2015 (ADAMS Accession Nos. ML15317A361, ML15351A113, and ML15355A413, respectively), Tennessee Valley Authority (TVA) submitted a license amendment request (LAR) for the Browns Ferry Nuclear Plant (BFN), Units 1, 2, and 3. The proposed amendment would increase the authorized maximum steady-state reactor core power level for each unit from 3,458 megawatt thermal (MWt) to 3,952 MWt. This LAR represents an increase of approximately 20 percent above the original licensed thermal power level of 3,293 MWt, and an increase of approximately 14.3 percent above the current licensed thermal power level of 3,458 MWt.

The U.S. Nuclear Regulatory Commission (NRC) staff reviewed the licensee's submittals and determined that additional information is needed. On January 13, 2016, the NRC staff forwarded, by electronic mail, a draft of the staff's request for additional information (RAI) to TVA. On January 15, 2015, TVA informed the NRC staff that no clarification call is needed.

The official questions are found in the enclosed RAI. This request was discussed with Mr. Daniel Green of your staff, and it was agreed that TVA would respond by February 16, 2016.

J. Shea If you have any questions, please contact me at 301-415-1447 or Farideh.Saba@nrc.gov.

Sincerely, Farideh E. Saba, Senior Project Manager Plant Licensing Branch 11-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-259, 50-260, and 50-296

Enclosure:

Request for Additional Information cc w/enclosure: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST RELATED TO EXTENDED POWER UPRATE LICENSE AMENDMENT REQUEST TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT, UNITS 1, 2, AND 3 DOCKET NOS. 50-259, 50-260, AND 50-296 By letter dated September 21, 2015 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15282A152), as supplemented by letters dated November 13, December 15, and December 18, 2015 (ADAMS Accession Nos. ML15317A361, ML15351A113, and ML15355A413, respectively), Tennessee Valley Authority (the licensee) submitted a license amendment request (LAR) for the Browns Ferry Nuclear Plant (BFN),

Units 1, 2, and 3. The proposed amendment would increase the authorized maximum steady-state reactor core power level for each unit from 3,458 megawatt thermal (MWt) to 3,952 MWt. This LAR represents an increase of approximately 20 percent above the original licensed thermal power level of 3,293 MWt, and an increase of approximately 14.3 percent above the current licensed thermal power level of 3,458 MWt.

The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the information the licensee provided and determined that the following additional information associated with spent fuel pool (SFP) is required in order to complete the evaluation.

SFP-Reguest for Additional Information (RAI) 1 Section 50.36(c)(4) of Title 1O of the Code of Federal Regulations (10 CFR) states, in part, that, "Design features to be included [in the technical specifications (TSs)] are those features of the facility such as materials of construction and geometric arrangements, which, if altered or modified, would have a significant effect on safety." BFN TS 4.3.1.1 (a) requires a keff (effective neutron multiplication factor (aka k-effective)) of equal or less than 0.95, consistent with 10 CFR 50.68. The NRC staff notes the calculated keff found in the SFP nuclear criticality safety (NCS) analysis, in Section 2 of ANP-3160(NP), Revision 1 (attached as Enclosure 2 to the letter dated December 15, 2015), is determined, in part, from an upper limit on the reactivity of the fuel lattice used in the NCS analysis. In the NCS analysis, this limit is expressed as the maximum k~ (infinite lattice neutron multiplication factor (aka k-infinity)) calculated for fuel stored in the SFP rack geometry. The calculated keff is used to demonstrate compliance with the keff TS requirement. Therefore, the maximum allowable reactivity of fuel that may be stored in the SFP is a key feature in ensuring that the SFP subcriticality safety requirement is met.

Discuss what limits or controls the licensee is implementing to ensure that the reactivity of the fuel stored in the SFP does not exceed the bounds of the NCS analysis, ensuring that the regulatory requirement to maintain the TS value of keff less than 0.95 continues to be met.

Enclosure

SFP-RAI 2 The NCS analyses submitted by the licensee are used to demonstrate the regulatory requirement of 10 CFR 50.68(b)(4), which states, in part, that, "the k-effective of the spent fuel storage racks loaded with fuel of the maximum fuel assembly reactivity must not exceed 0.95, at a 95 percent probability, 95 percent confidence level, if flooded with borated water, and the k-effective must remain below 1.0 (subcritical), at a 95 percent probability, 95 percent confidence level, if flooded with unborated water." This requirement is evaluated against both normal conditions and postulated accident conditions. In the NCS analysis, the limiting accident condition is one in which a single Boral plate is missing.

In the previous SFP LAR dated September 21, 1978 (ADAMS Accession No. ML020040269),

which the NRC staff reviewed and approved in 1978, the licensee evaluated an accident condition where up to four Boral plates were missing. As part of this LAR, the licensee stated that, "the presence of the neutron absorber material in the fabricated fuel storage module will be verified at the reactor storage-pool site by use of a neutron source and neutron detectors." The licensee states there will be a permanent record of all test results and that, "a module will be accepted unless measurements indicate that five or more Boral sheets are not present."

Section 10.3.6 of the BFN Updated Final Safety Analysis Report states that each rack was tested prior to installation to check for missing Boral plates. However, the information available to the NRC does not provide clear assurance that the testing results showed that no Boral plates were found to be missing. Given that the limiting accident condition assumes fewer missing Boral plates than allowed by the acceptance criteria associated with initial receipt of the rack modules, the possibility exists for an unanalyzed condition that challenges the calculated margin to the regulatory limit.

Provide information that demonstrates that the testing of the neutron attenuation of each tube in each rack prior to installation showed that no more than one Boral plate was missing from any of the prescribed locations in the fabricated fuel storage modules, even though the criteria for acceptance of each rack modules would have allowed for some missing plates.

ML16019A283 *via email OFFICE NRR/DORL/LPLll-2/PM NRR/DORL/LPLI 1-2/LA N RR/DSS/SN PB/BC*

NAME FSaba (LRonewicz for) BClavton JDean DATE 1/19/2016 1/19/2016 1/21/2016 OFFICE NRR/DORL/LPLI 1-2/BC NRR/DORL/LPLll-2/PM NAME BBeasley FSaba ,,

DATE 1/22/2016 1/28/2016