ML18107A198

Responds to 990312 RAI Re Request for Change to TSs Permissible Enrichment Values for New Fuel Storage,Which Was Submitted on 990202

ML18107A198
Person / Time
Site:	Salem
Issue date:	04/12/1999
From:	Eric Simpson Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LCR-S98-17, LR-N990170, NUDOCS 9904220220
Download: ML18107A198 (4)

Text

.'

Public Service Electric and Gas Company E. C. Simpson Public Service Electric and Gas Company P.O. Box 236, Hancocks Bridge, NJ 08038 609-339-1700 Senior Vice President - Nuclear Engineering APR111999 LR-N990170 LCR S98-17 United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Gentlemen:

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING REQUEST FOR CHANGE TO TECHNICAL SPECIFICATIONS PERMISSIBLE ENRICHMENT VALUES FOR NEW FUEL STORAGE SALEM GENERATING STATION UNIT NOS. 1 AND 2 DOCKET NOS. 50-272 AND 50-311 By letter dated March 12, 1999 NRC forwarded four questions regarding PSE&G Request for Change to Technical Specifications which had been submitted by letter LR-N990056 dated February 2, 1999. These questions are restated in Attachment 1 to this letter along with our responses.

Should you have any questions regarding this request, please contact John Nagle, Salem Licensing, at (609) 339-3171.

/jcn Attachment (1) 9904220220 990412 PDR ADOCK 05000272 P _ PDR a\ Printed on

~ Recycled Paper

APR11199Sl

• Document Control Desk LR-N990170 C Mr. H. J. Miller, Administrator - Region I U. S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 Mr. P Milano, Licensing Project Manager - Salem U. S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 14E21 Rockville, MD 20852 Mr. S. Morris (X24)

USNRC Senior Resident Inspector Mr. K. Tosch, Manager IV Bureau of Nuclear Engineering 33 Arctic Parkway CN 415 Trenton, NJ 08625 95-4933

Document Control Desk Attachment I e

LRN990170 LCR S98-017 SALEM GENERATING STATION UNIT NOS. 1 AND 2 FACILITY OPERATING LICENSES DPR - 70 AND DRP - 75 DOCKET NOS. 50-272 AND 50-311 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING CHANGE TO TECHNICAL SPECIFICATIONS PERMISSIBLE ENRICHMENT VALUES FOR NEW FUEL STORAGE Question 1: Two analytical techniques are used to. determine the acceptability of storage of fuel assemblies with nominal enrichments greater than 4.65 wt% U-235. The first method is based on the reactivity decrease associated with the addition of Integral Fuel Burnable Absorbers (IFBAs). The second method uses the fuel assembly infinite multiplication factor (K-infinity) to establish a reference reactivity. The first method is incorporated into the technical specifications by specifying the number of IFBA rods required for fuel assembly storage. Since K-infinity will be used as an alternate method for determining the acceptability of fuel storage in the fresh fuel racks, why is there no k-infinity technical specification?

Response to Question 1: The K-infinity method is an alternate method for determining equivalence and supplements the IFBA credit data determined in the analysis of the fresh fuel racks. The IFBA credit method is used by PSE&G to ensure that the applicable criticality limits are met (Ke~0.95 under full density moderation conditions, Keff :s;0.98 under optimum moderation conditions). Use of the K-infinity method along with the IFBA credit data would be redundant and unneccessary. The K-infinity method of determining equivalent reactivity has been recently identified by Westinghouse to be potentially non-conservative, since it does not take into account the actual rack geometry and associated neutronic impacts. As a result, PSE&G has decided not to implement the K-infinity Technical Specification.

Question 2: The fresh fuel racks have been analyzed for both full density water flooding, where K-effective does not exceed 0.95, and for optimum low-density moderation conditions, where K-effective does not exceed 0.98. This is consistent with the NRC Standard Review Plan 9.1.1 and with the Improved Technical Specifications. The first criterion requiring k-eff to be less than or equal to 0.95 if fully flooded with unborated water has been incorporated in the Technical Specifications. Why is there no technical specification requiring k-eff to be less than or equal to 0.98 under the low-density optimum moderation accident conditions?

Response to Question 2:* The fresh fuel rack Keff is a function of the geometry (center-to-center distance), enrichment I burnable absorber content of the fresh fuel and the water density which is assumed. The maximum Keff value assumed Page I of2

-.., Document Control Desk Attachment 1 e

LR N990170 LCRS98-017 for th~ full density and optimum moderation analyses are really the design bases

• for the fresh fuel rack and are not a necessary part of the Technical Specification.

Meeting the enrichment, burnable absorber, and geometry Technical Specification requirements of the fresh fuel racks provides assurance that the design basis Kett values for the fresh fuel racks will be met. Thus the fresh fuel racks will remain adequately subcritical under all postulated moderation and accident conditions.

Review of the Standard Technical Specifications shows that the fully flooded Kett and the opimum moderation Kettare used. As a result, PSE&G will include the low density accident Kett as part of the fresh fuel rack Technical Specification.

Question 3: The k-infinity of 1.480 was based on a 17x17 V5H assembly enriched to 4.65 wt% U-235.Since the IFBA pin numbers have been changed to be consistent with the spent fuel pool storage requirements (i.e. 4.25 wt%), is this k-infinity value still valid or should it be modified to be consistent with a 4.25 wt%

enriched assembly?

Response to Question 3: Yes. The K-infinity value of 1.480 is still valid for the fresh fuel racks. However, due to potential non-conservatisms with this method, PSE&G does not plan to implement this method or include it in the Technical Specifications. Hence, the K-infinity value (1.480) determined in the Westinghouse fresh fuel rack analysis is not relevant to LCR S98-17 and does not need to be revised.

Based on the fresh fuel rack analysis which was attached to LCR S98-17, 4.65 w/o was determined to be the maximum enrichment which meets the Kett~ 0.95 (full density moderation case) and Kett~ 0.98 (low density moderation case) limits with no credit for IFBA. The fresh fuel rack criticality analysis developed equivalent pairs of enrichment and IFBA based on the no IFBA, 4.65 w/o assembly reference K-infinity value in fresh fuel rack geometry. The spent fuel pool storage maximum enrichment without IFBA credit in the Region 1 spent fuel racks was previously determined to be 4.25 w/o as part of the Salem reracking project. This enrichment formed the basis of the current Salem Technical Specification 5.6.1.2. IFBA credit requirements for enrichments >4.25 w/o in spent fuel rack geometry bound those for enrichments >4.65 w/o in fresh fuel rack geometry. Therefore, the 4.25 w/o spent fuel pool IFBA credit equation will be used for both the fresh fuel racks and the spent fuel racks for consistency and since this is conservative for the fresh fuel racks.

Question 4: Should the word "of' in Technical Specification 5.6.1.1.a be "or"?

Response to Question 4: The wording in Technical Specification 5.6.1.1.a should be "of' since PSE&G is not implementing the K-infinity method for determining equivalent reactivity.

Attachment 1Page2 of2