ML19323C867
| ML19323C867 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 05/12/1980 |
| From: | CONNECTICUT YANKEE ATOMIC POWER CO. |
| To: | |
| Shared Package | |
| ML19323C862 | List: |
| References | |
| NUDOCS 8005190335 | |
| Download: ML19323C867 (1) | |
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ATTACHMENT EVENT DESCRIPTION 5
l On April 28, 1980, at approximately 1940 hours0.0225 days <br />0.539 hours <br />0.00321 weeks <br />7.3817e-4 months <br /> the main stack RMS monitor increased from its background reading of approximately 400 cpm to approximately 950 cpm.
This event took place shortly after completion of a 2000 gallon dilution of the primary system.
Initial investigation of the cause could not be pinpointed but it did narrow the problem down to the waste gas system. This conclusion was sub-sequently verified by local air samples in the waste gas building.
By 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br /> the count rate on the stack RMS monitor had returned to its background level of approximately 400 cpm.
The release was calculated to be 5.6% of MPC and 9.98% of the instantaneous release rate allowed by Environmental Technical Specifications.
Calculations showed that 2.04 curies of Xe-133 and 2.60 curies of Xe-135 had been released.
Further calculations showed that the whole body dose at the site boundary from this release was calculated to be 3.7 ' micro-rem.
The waste gas system was shutdown until controlled testing could be performed in order to determine the cause of this release.
t EVENT CAUSE Furtiier testing of the waste gas system indicated that the leak path from the gas system to the waste disposal building was through the dcgasifier rupture disc flange.
The 'heatup and cooldown of the degasifier appears to have caused the flange to leak for a short period of time.
This leakage vented into the waste diposal building which is vented to the main stack.
CORRECTIVE ACTION The rupture disc flange was taken apart, the rupture disc replaced, the gaskets replaced, and the flange made backup.
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