ML19345G167
| ML19345G167 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 04/10/1974 |
| From: | Hartley F CONNECTICUT YANKEE ATOMIC POWER CO. |
| To: | |
| References | |
| AO-50-213-74-6, NUDOCS 8103090796 | |
| Download: ML19345G167 (2) | |
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h, $$d g [i3 ABNORMAL OCCURRENCE REPORT S
?7 APR161974 Report Number:
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Report Date_:
April 10,1974 -
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April 4, 1974 Facility:
Connecticut Yankee Atomic.'Mwer Company Identification of Occurrence:
Failure of Containment Penetration P-60 (Component Cooling Water Supply To The Neutron Shield Tank Cooler) Check Valve To Meet an Acceptable Leak Rate During Periodic Testing Conditions Prior to Occurrence:
Residual Heat Removal System in operation.
Reactor Coolant System 125F, 0 atmospheric pressure.
Description of Occurrence:
A routine periodic Containment Penetration Leak Rate Test of P-60 (Component Cooling Water Supply to Neutron Shield Tank Cooler) was conducted on 4-4-74.
Mathematical calculations relating liquid test leakage to equivalent pounds of air 0 40 psig were performed which determined the penetration leakage to be 2,715 lbs. air / day 0 40 psig.
As the maximum leakrate for all containment penetrations is equivalent to 1470 lbs. air / day 0 40 psig, the leakrate for this one penetration exceeded the total allowable.
Designation of Apparent Cause of Occurrence:
An investigation revealed that small particles of scale lodging between stem and guide bushing of the spring loaded check valve, maintained the valve disc in the open position. This system is in continuous operation except for short outage periods for maintenance or testing. The valve is open when the system is operating.
Analysis of Occurrence:
This check valve is a secondary containment boundary. The primary boundary consists of the piping and cooler which this line supplies with cooling water. Only a leak in the primary boundary wculd allow passage of containment air back through this check valve and then only if the component cooling water system is shutdown (normal operating pressure for this system is 75 psig and containment design pressure is 40 psig.) It is our opinion the occurrence presented no undue hazard or risk to personnel or public.
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ABNORMAL OCCURRENCE REPORT No. 50-213-74-6 _ (Continued)
Corrective Action:
The check valve cover was removed and the valve disc found in the open position. The valve was disassembled and cleansd. All mechanical parts were in good condition.
Small particles of scale were found lodged between the stem and stem guide.
Following inspection and cleaning the valve was re-assembled and a penetration retest performed with favorable results. (3.53 lbs. air / day 0 40 psig) on 4-5-74.
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F. W. Hartley C
Plant. Superintendent i
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