ML20043B756

Informs That Util Intends to Utilize Relationship Between Frosstey & FROSSTEY-2 to Support Cycle 15 Calculations.Nrc Approval of FROSSTEY-2 Needed by Aug 1990 for LOCA Analysis Program

ML20043B756
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	05/23/1990
From:	Tremblay L VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
BVY-90-061, BVY-90-61, NUDOCS 9005310242
Download: ML20043B756 (2)

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' VERMONT YANKEE NUCLEAR POWER CORPORATION

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y- Ferry Road. Brattleboro, VT 053017002

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ENGINEERING OFFICE

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$80 MAIN STREE1 DOLTON. M A 01740 (508)779 4711 May 23,1990 BVY 90-061 i United Str as Nuclear Regulatory Commission J Document Control Desk Washington,DC 20555

References:

a) License No. DPR 28 (Docket No. 50-271) b) Letter, USNRC to VYNPC, NVY 85-205, dated September 27,1985

.- c) Letter, VYNPC to USNRC, FVY 87 116, dated December 16,1987 d) letter, VYNPC to USNRC, FVY 88=89, dated October 13,1988

'1 e) Letter, USNRC to VYNPC, NVY 89 241 dated December 11,1989 f) letter, USNRC to VYNPC, NVY 89-242, dated December 12,1989 g) letter, USNRC to YAEC, NVY 90-032, dated February 20,1990 h) Letter, USNRC to VYNPC, NVY 90-051, dated Mamh 9,1990 i) 12tter, USNRC to VYNPC, NVY 90-053, dated Mamh 15,1990 i

k))I Letter, USNRC oter, VYNPC to YA"C, to USNRC, BVY NVY 90-054, 90-045, dated dated April March 21,1990 19,1990 l) Leuet, VYNPC to USNRC, BVY 90-054, dated May 10,1990

Subject:

Status of Vermont Yankee Cycle 15 Reload Methods Approvals

Dear Sir:

By letter dated October 13,1988 (Reference (d)), Vermont Yankee outlined the schedules for submittal and use of new analysis methods for defining the operating limits contained in the Vermont Yankee Core Operating Limits Report. Since that time, the NRC Staff has approved SLICK (Reference (c)), the 1 D Kinetics Option of RETRAN (Reference (f)), SIMULATE 1 (Reference (g)), CASMO 3 (Reference (j)), and the Vennont Yankee Specific Benchmarking (Reference (i)). These methods have been approved as a result of a concentrated effort by the NRC Staff on a schedule fully consistent with Vermont Yankee's refueling licensing requirements for Cycle 15.

The only remaining approval requested for Cycle 15 is FROSSTEY-2, a revision of the previously approved fuel performance computer code FROSSTEY (Reference (b)) submitted as part of Yankee Atomic Electric Company's program to obtain state-of the art LOCA analysis capability for Vermont Yankee (Reference (c)). This modified code is currently under review by

'the USNRC, By Reference (h), NRC transmitted four (4) questions to Vermont Yankee which have resulted from staff review of FROSSTEY 2. Vermont Yankee has provided responses to Questions 1 and 4 of Reference (h) by means of References (k) and (1). Responses to Questions 2 and 3 of Reference (h) have required a significant amount of time and effort on the part of Yemiont

. Yankee. Additional time to respond to these remaining questions beyond the date provided in m References (k) and (1) was irquested from and granted by tbe NRC Project Manager (M. Fairtile) per a May 17,1990 telecon. Vermont Yankee is working on an expedited basis to complete its response to Questions 2 and 3 of Refc>ence (h), and plans to submit such responses in the near future.

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J United States Nuclear Regulatory Commission -

May 23,1990 Page 2 i

Given that the Vermont Yankee Cycle 15 reload calculations have already been performed with the FROSSTEY 2 code, an effort was initiated to develo an altemative strategy with respect to the -

use of FROSSTEY-2 strictly for Cycle 15 reload analys pur)oses. As a part of this effort,recent calculations have determined that the FROSSTEY coce yleids results equivalent to the FROSSTEY code when applied to Cycle 15 reload calculations of gap conductance and linear heat generation rates corresponding to 1% claddinll plastic strain and fuel cc. terline melting. This 1 "workarotm:l" strategy was discussed with the NRC Project Manager and cognizant members of NRC Staff during a visit to NRC headq uarters by representatives of Vermont Yankee on May 2, 1990.. NRC staff members attending this meeting agreed that the use of this workaround strategy for Cycle 15 reload analysis purposes qualified as an acceptable altemative strategy, and requested that Vennont Yankee formahze its intentions in writing.

i Accordingly, please be infomied that Vermont Yankee intends to utilire the above described -

relationshi-) between FROSSTEY and FROSSTEY 2 to support Cycle 15 reload calculations that have alreac y been performed with FROSSTEY-2. Immediate approval of FROSSTEY 2 for Cycle L 15 reload analysis purposes is therefore no longer required. However, approval of FROSSTEY 2 by August 1990 is still needed for the Vennont Yankee specific LOCA analysis pro;; ram.

Therefore, we request that the review priority assigned to FROSSTEY 2 be consistent wit i that assigned to the ongoing review of Vermont Yankee's LOCA analysis methods. Vermont Yankee is expediting its response to remaining staff questions regarding FROSSTEY-2 to accommodate this review schedule, We trust that the information provided above is acceptable; however, should you have any questions in this matter, please coautet us.

Very truly yours,

, VERMONT YANKEE NUCLEAR POWER CORPORATION MMt b, Leonard A.Tremblay,Jr. Y Senior Licensing Engineer cc: USNRC Regional Administrator, Region i USNRC Resident Inspector VYNPS USNRC Project Manager VYNPS l

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