ML19309B964
| ML19309B964 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 03/10/1980 |
| From: | Ippolito T Office of Nuclear Reactor Regulation |
| To: | Rich Smith VERMONT YANKEE NUCLEAR POWER CORP. |
| References | |
| NUDOCS 8004070408 | |
| Download: ML19309B964 (3) | |
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March 10,1980 Docket No. 50-271 Mr. Robert L. Smith Licensing Engineer Vermont Yankee Nuclear Power Corporation 25 Research Drive Westboro, Massachusetts 01581
Dear Mr. Smith:
During the last several years, data have begun to indicate that the fission gas release rate from LWR fuel pellets is increased (enhanced) with burnup. Many of the current fuel performance analyses do not consider the impact of burnup release on safety. By letters dated November 23, 1976, the NRC staff requested all LWR licensees to assess the higher fission gas release for fuel burnups above 20,000 Megawatt-day per metric ton (MWD /T).
Also, by NRC staff letter dated January 18, 1978, all U. S. LWR fuel suppliers were requested to revise their fuel performance analyses to include the enhancement of fission gas release at higher burnups.
All responses to the November 23, 1976 letters have been reviewed. We have concluded that no immediate licensing action is required for operat-
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ing reactors. This conclusion is valid for typical reported LWR fuel bundle and batch burnups. Any extension of these burnups or other fac-tors which significantly affect fission gas release, LOCA PCT or fuel rod internal pressure is outside the scope of the conclusion.
The effect of enhanced release on BWR ECCS performance has been discussed with General Electric (GE). GE has pointed out that because of opera-tional restrictions and physical limitations, the LOCA analysis is not limiting in high burnup fuel (25,000 WD/T). High burnup fuel generally cannot achieve linear power densities near the LOCA limit early in cycle.
The limiting fuel bundle is usually in its second cycle of reactor opera-tions where burnup levels are below -20,000 ND/T. Late in a BWR fuel cycle, there is less axial power peaking reducing the feasibility for any given axial location to exceed LOCA linear power density limits, and the fuel bundle power is generally limited by MCPR considerations. Thus, it is unlikely that a high burnup bundle can exceed the ECCS performance criteria in case of a LOCA. The argument is appropriate for Exxon fuel bundle design also based on the review of Exxon analyses for operating BWRs.
Therefore, no imediate licensing action is necessary on operating BWRs.
8004070/
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Mr. Robert L. Smith Inasmuch as you and/or the staff will be evaluating all future reloads against fuel vendors' revised fuel performance codes which provide for increase in fission gas release at higher burnups, we consider this a satisfactory resolution of this concern.
Sincerely.
[
o, Chief Operating Reactors Branch #3 Division of Operating Reactors cc: See next page e
Mr. Robert L. Smith cc:
Ms. J. M. Abbey John R. Stanton, Director Vermont Yankee Nuclear Power Radiation Control Agency Corporation Hazen Drive 77 Grove Street Concord, New Hampshire 03301 Rutland, Vermont 05701 John W. Stevens Mr. Donald E. Vandenburgh, Conservation Society of Vice President Southern Vermont Vermont Yankee Nuclear Power P. O. Box 256 Corporation Townshend, Vermont 05353 Turnpike Road, Route 9 Westboro, Massachusetts 01581 Dr. Mars Longley, Director Occupational & Radiological Health John A. Ritsher, Esquire 10 Baldwin Stre,et Ropes & Gray Montpelier, Vermont 05602 225 Franklin Street Boston, Massachusetts 02110 kew England Coalition on Nuclear Pollution Laurie Burt Hill and Dale Farm Assistant Attorney, General West Hill - Faraway Road Environmental Protection Division Putney, Vermont 05346 Attorney General's Office One Ashburton Place, 19th Floor Public Service Board Boston Massachusetts 02108 State of Vermont 120 State Street Ronald J. Wilson Montpelier, Vermont 05602 81018th Street, N. W.
Suite 802 W. F. Conway, Plant Superintendent Washington, D. C.
20006 Vermont Yankee Nuclear Power Corporation Honorable M. Jerome Diamond P. O. Box 157 Attorney General Vernen, Vermont 05354 State of Vermont 109 State Street Mr. Charles Sheketoff Pavilion Office Building Assistant Director Montpelier, Vermont 05602 Vermont Public Interest Research Group, Inc.
Mr. J. E. Griffin, President 26 State Street Vermont Yankee Nuclear Powe Montpelier, Vermont 05602 Corporation 77 Grove Street Brooks Memorial Library Rutland, Vermont 05701 224 Main Street Brattleboro, Vermont 05301
.