ML17252B063
| ML17252B063 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 05/08/1972 |
| From: | Grier B US Atomic Energy Commission (AEC) |
| To: | Brian Lee Commonwealth Edison Co |
| References | |
| Download: ML17252B063 (2) | |
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UNITED STATES ATOMIC.ENERGY COMMISSION DIRECTORATE OF REGULATORY OPERATIONS REGION Ill 799 ROOSEVELT ROAD,.
GLEN ELLYN9 ILLINOIS 60137 May 8, 1972 TELEPHONE (312) 858-2660 Commonwealth Edison Company ATTN:
Mr. Byron Lee, Jr.
Docket No. S0-249 Assistant to the President P. O. Box 767 Chicago, Illinois '60690 Gentlemen:
This acknowledges the notification received by Mr. Dance of this office on May 4, 1972, regarding an unplanned automatic shutdown of Dresden Unit 3 which occurred at 9:01 a.m. on May 4.
We were informed that the shutdown was followed by a primary system pressure transient which resulted in the discharge of steam through a safety valve to the containment building drywell.
We were also informed that there was no unplanned release of radioactive materials from the drywell as a result of this occurrence.
Based on subsequent discussions by our inspectors with representatives of your staff, both at the site and by telephone, it is our understanding that your investigation into this occurrence is continuing but that the precise cause of the automatic shutdown has not been determined, and was apparently the result of a spurious signal. It is our further understanding that adjustments will be made to the controls for the valve in the isolation condenser system which malfunctioned subsequent to the shutdown and tha_t proper operation of this valve will be demonstrated prior to resuming operations, and that the safety valve which lifted during the pressure transient will be replaced with a properly tested valve, also prior to resuming operations. Further, it is our understanding that you are expediting your program to establish the cause for the lifting of a safety valve at an apparent steam pressure less than that for which the valve was set to relieve.
We will examine your action on these matters during our ~ubsequent inspections.
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.;!.1 Commonwealth Edison Company May a. 1912 Should you* have any qu<i~~ii:ins regarding these~: *matter*s, we will be pleased to discuss them.with you.
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S'incerely yours*
Boyce 1i. Grier.
- Regional Director bee:
J.. G. Keppler, RO R. H. Engelken, RO P. A. Morris, RO A. Giambusso, L RO Files DR* Central* Files PDR NSIC DTIE
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