ML13308B515
| ML13308B515 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 07/29/1972 |
| From: | Coe R SOUTHERN CALIFORNIA EDISON CO. |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8103060684 | |
| Download: ML13308B515 (2) | |
Text
Southern California Edison Company P 0. BOX 800 Regulatory File Cy.
2244 WALNUT GROVE AVENUE ROBERT N. COE ROSEMEAD, CALIFORNIA 91770 TELEPHONE VicE PRESIDENT August 28, 1972 Director Directorate of Licensing U. S. Atomic Energy Commission 1717 "H" Street, N. W.
Washington, D. C. 20545 sion2
Dear Sir:
On May 9, 1972, Southern California Edison Company notified your office that unit load restrictions due to turbine overspeed considerations had been removed.
It was felt at the time that equipment modifications and improved overspeed predic tability rendered this action prudent.
On July 29, 1972, the unit tripped from full load (450 MWe gross) due to a generator loss of field trip. The unit reached 133% overspeed. This value was approximately 2%
greater than anticipated. Complete evaluation of this incident is in progress.
However, for conservatism, unit load restrictions were considered prudent. Consequently, the maximum unit load is currently limited according to the following program:
Maximum Load (Gross)
Minimum Condenser MWe Back Pressure 440 2.00" Hg 435 1.75" Hg 430 1.50" Hg These limitations serve to provide reasonable assur ance that the turbine will not exceed 133% overspeed in the event of a unit trip coincident with governor failure. These restrictions are based upon the most recently observed over speed values.
4834
-2 Evaluation of the turbine overspeed characteristics continues. Design of reheat interceptor and stop valves and/
or a steam dump system is in progress.
Very truly yours, JCS:dl