ML19345G168
| ML19345G168 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 04/04/1974 |
| From: | Hartley F CONNECTICUT YANKEE ATOMIC POWER CO. |
| To: | |
| References | |
| AO-50-213-74-5, NUDOCS 8103090802 | |
| Download: ML19345G168 (2) | |
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ABNORMAL OCCURRENCE REPORT f
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50-213 74-5 Report Date:
4-4-74 E*N$d[
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3-27-74 Facility:
Connecticut Yankee Atomic Power Company Identification of Occurrence:
Malfunction of Reactor Coolant Letdown Motor Operated Stop Valve Conditions Prior to Occurrence: Cold Shutdown Description of Occurrence:
The Reactor Coolant System letdown line is provided with a remotely operated isolation valve to automatically isolate the Reactor Coolant System from the Chemical and Volume Control System. This val.e closes automatically upon safety injection actuation signal.
After completing a reactor coolant system cooldown and depressurization evolution, the control room operator attempted to close the Letdown Motor Operated Isolation Valve (MOV-200) by actuating the control switch at the main control board. The main control board valve in-dication showed that the valve had not completed its closing cycle.
A local check revealed the valve in the half shut position. An attempt to manually close the valve failed.
Designation of Apparent Cause of Occurrence:
An investigation by maintenance personnel revealed that the packing gland was tightened to the extent that the valve would not function properly.
It appears that the valve packing dried in the cooldown process.
It is our opinion that the valve would have operated as required with the plant at normal operating temperature.
Analysis of Occurrence:
This stop valve is located close to the loop piping and closes upon actuation of core cooling.
It functions to protect the reactor coolant system from a letdown line break. The only conceivable condition in which the public safety would be compromised is the simultaneous rupture of the letdown line and malfunction of the valve in question.
Since the letdown line was not breeched during the period when the letdown line isolation valve was not operating properly, we conclude that the public health and safety was not compromised as a result of this occurrence.
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i AB!l0RfiAL OCCURRENCE REPORT No. 50-213 74-5 (Continued)
Corrective Action:
The valve packing gland was adjusted followed by a successful operability check in the cold condition. The valve operability will be verified upon reaching normal operating-temperatures.
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s F. W. Hartley Plant Superinten//
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Page 2 of 2
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