ML19296D709
| ML19296D709 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 02/25/1980 |
| From: | Schwencer A Office of Nuclear Reactor Regulation |
| To: | Mayer L NORTHERN STATES POWER CO. |
| References | |
| NUDOCS 8003130044 | |
| Download: ML19296D709 (3) | |
Text
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%,.....f FEBRUARY 2 5 7980 Docket Nos. 50-282 and 50-306 Mr. L. O. Mayer, Manager Nuclear Support Services Northern States Power Company 414 Nicollet Mall - 8th Floor Minneapolis, Minnesota 55401
Dear Mr. Mayer:
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-enhanced release on safety.
By letters dated November 23,1976, the NRC staff requested all LWR licensees to assess the hicher fission gas release for fuel burnups above 20,000 Megawatt-day per metric.on (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 enhance-ment 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 operating reactors.
This conclusion is valid for typical reported LWR fuel bundle and batch burnups.
Any extension of these burnups or other factors which significantly affect fission gas release, LOCA PCT or fuel rod internal pressure is outside the scope of the conclusion.
Westinghouse was the only fuel supplier calculating that the increased release would cause internal fuel rod pressure to exceed coolant system pressure. The staff has approved revised design criteria which allow internal rod pressures greater than system pressure.
The staff is also completing the review of a Westinghouse revised fuel performance code. The staff, in evaluating reloads, has been requesting licensees using Westinghouse fuel to quantify the burnup when the newly approved design criteria will be violated.
In the reloads evaluated thus far, there appears to be significant burnup margin to the newly approved design criteria to compensate for modifications which may result from the staff review of the Westinghouse revised fuel performance code.
The responses concerning Combustion Engineering (CE) and Exxon PWR fuel bundles demonstrated that neither was there an adverse effect on ECCS evaluations nor did the internal fuel rod pressure exceed system pressure.
Therefore, no immediate licensing action is necessary on CE or Exxon fueled PWRs.
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Mr. L. O. Mayer FtsRuray 2 5 g o 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,/
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A. Schwencer, Chief Operating Reactors Branch #1 Division of Operating Reactors cc: See next page
Mr. L. O. Mayer Northern States Power Company FEBRUARY ? 5 800 cc: Gerald Charnoff, Esquire Shaw, Pittman, Potts and Trowbridge 1800 M Street, N.W.
Washington, D. C.
20036 Ms. Terry Hoffman Executive Director Minnesota Pollution Control Agency 1935 W. County Road B2 Roseville, Minnesota 55113 The Environmental Conservation Library Minneapolis Public Library 300 Nicollet Mall Minneapolis, Minnesota 55401 Mr. F. P. Tierney, Plant Manager Prairie Island Nuclear Generating Plant Northern States Power Company Route 2 Welch, Minnesota 55089 Joclyn F. Olson, Esquire Special Assistant Attorney General Minnesota Pollution Control Agency 1935 W. County Road B2 Roseville, Minnesota 55113 Robert L. t(ybo, Jr., Chairman Minnesota-Wisconsin Boundary Area Commission 619 Second Street Huds.on, Wisconsin 54016 Clarence D. Fierabend U. S. Nuclear Regulatory Commission P. O. Box 374 Red Wing, Minnesota 55066
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