ML13322A749
| ML13322A749 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 02/29/1980 |
| From: | Ziemann D Office of Nuclear Reactor Regulation |
| To: | Dietch R Southern California Edison Co |
| References | |
| NUDOCS 8004090242 | |
| Download: ML13322A749 (3) | |
Text
Docket No. 50-206 Mr. R. Dietch Vice President Nuclear Engineering and Operations Southern California Edison Company 2244 Walnut Grove Avenue Post Office Box 300 Rosemead, California 91770
Dear Mr. Dietch:
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 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 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 burn ups. 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 fIel supplier calculating that the increased release would cause internal fuel rod pressure to exceed coolant system pressure. The staff has approved revised jesign 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 dejign criteria will be violated. In the reloads eval uated thus far, there appears to be a significant burnup margin to the newly approved evaluated design criteria to compensate for modifications which may result from the staff's review of the Westinghouse revised fuel performance code.
Soo 9
OFFICE IT....--
S U R N A M E DATE.
0 vFNM6...................................................9 NRC FORM 318 (9-76) N'RCNI 0240
- U.S.
GOVERNMENT PRINTING OFFICE: 1979-289-369
Mr. R. Dietch 2
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, Dennis L. Ziemann, Chief Operating Reactors Branch #2 Division of Operating Reactors cc: -See next page DISTRIBUTION Docket NRC PDR Local PDR ORB #2 Reading NRR Reading DLZiemann HSmith ABurger MMendonca PCheck OELD OI&E (3)
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DATE
.J2/1 NRC FORM 318 (9-761 NRCM10240
-3ZU.S. GOVERNMENT PRINTING OFFICE: 1979-289-.369
Mr. February 29, 1980 cc Charles R. Kocher, Assistant Director, Technic& Assessment General Counsel Division Southern California Edison Company Office of Radiation Programs Post Office Box 800 (AW-459)
Rosemead, California 91770 U. S. Environmental Protection Agency David R. Pigott Crystal Mall #2 Samuel B. Casey Arlington, Virginia 20460 Chickering & Gregory Three Embarcadero Center U. S. Environmental Protection Twenty-Third Floor Agency San Francisco, California 94111 Region IX Office ATTN:
EIS COORDINATOR Jack E. Thomas 215 Freemont Street Harry B. Stoehr San Francisco, California 94111 San Diego Gas & Electric Company P. 0. Box 1831 San Diego, California 92112 Resident Inspector c/o U. S. NRC P. 0. Box 3550 SanOnofre, California 92672 Mission Viejo Branch Library 24851 Chrisanta Drive Mission Viejo, California 92676 Mayor City of San Clemente San Clemente, California 92672 Chai rman Board of Supervisors County of San Diego San Diego, California 92101 California Department of Health ATTN:
Chief, Environmental Radiation Control Unit Radiological Health Section 714 P Street, Room 498 Sacramento, California 95814