ML19345G181
| ML19345G181 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 11/13/1973 |
| From: | Hartley F CONNECTICUT YANKEE ATOMIC POWER CO. |
| To: | Anthony Giambusso US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| AO-73-11, CYH-2504, NUDOCS 8103100245 | |
| Download: ML19345G181 (3) | |
Text
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CONNECTICUT YA N K EE AT O M IC POWER COMPANY I
HADDAM NECK PLANT RR 21. BOX 127E, EAST H AMPTON, CONN. 06424 L
November 13, 1973 Mr. A. Giambusso
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Dear Mr. Giambusso:
As defined by Technical Specifications for Connecticut Yankee Atomic Power Station, the following report involving an unplanned release of radioactive material from the site is reported as Abnormal Occurrence 73-11.
During routine rounds an auxiliary operator detected water leaking from a tell tale on the RWST thermosiphon heater return isolation valve.
This tank is located outside, within the " controlled" area; consequently the water leaking from the valve was spilling on black top and drainina into a local storm sewer drain. This occurred at 10:30 P.M. on November 1.
The operator immediately closed the valve thereby reducing the leak substantially. A hose was then installed on the tell tale to direct further leakage to the aerated drains collection tank. The last person known to have inspected this area at 5:30 P.M. reports that he noticed nothing unusual.
Based on the auxiliary operators description of the leak and the elapsed time since the area had been inspected earlier it could have been leaking a maximum of 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> and the estimated volume that could l
have been discharged is calculated to be 270 liters. This was diluted l
with a service water flow of 6,000 gpm before leaving the plant site.
Subsequent analysis of the storm sewer indicated that some radioactive liquid had been discharged. Analysis of the gross activity content in the refueling water storage tank at the time was 1.3 x 10-3 pc/cc.
i l
The failed valve had not been operated recently and it appears that automatic initiation of heating steam to the heater caused the diaphragm l
to begin leaking. The steam system had not been in service since last l
spring.
At no time could the site boundary concentrations MPC limits have l
been approached. The release values are shown in Attachment A to this report.
The valve in question is an ITT Grinnel diaphragm valve. The diaphragm is designed to isolate the working parts from the fluid stream. A vent f',311 I
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9 Mr. A. Giambusso November 13, 1973 plug'provides a means of checking the integrity of the diaphragm under service conditions. The vendors representative recommends replacing the existing carbon steel valve bonnet with a bonnet constructed of stainless steel.
In addition to the stainless steel bonnet, the valve diaphragm will be replaced with a cured rubberized diaphragm having an extended litetime. Also a travel stop device will be installed on the valve stem to prevent over compression of the diaphragm on the body weir.
As reported in Abnormal Occurrence 73-6 dated July 3,.1973, valves of similiar service will be modified to accept a travel stop device.
Additionally the rubberized diaphragms will be replaced with diaphragms having an extended lifetime.
It is anticipated that refueling interval replacement of the valve diaphragm and the addition of a travel stop device will prevent recurrence of this type failure.
Very truly yours,
/&V F. W. Hartley gf,PlantSuperintendent RHG/bn Attachment
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't ATTACHMENT A MPC site Bounaary lo ta i. acti vi ty Isotope uc/mi Concentration pc/mi-Released.pCi.
1 Co-58 9 x 10-5 9.36 x 10-8pCi/ml 6.36 x 10 pCi 2
2 CO-60 3 x 10-5 4.74 x 10-8pCi/ml 3.22 x 10 pci Ce-144 1 x 10-5 4.38 x' 10-8pCi/ml 2.98 x 10
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2 Ci Ru-103 8 x 10-5 2.2 x 10-8 pCi/ml 1.49 x 10 pCi 2
Cr-51 2 r. 10-3 7.74 x 10-8pCi/ml 5.26 x 10 pCi 2
H-3 3 x 10-3 2.75 x 10-5 Ci/ml 1.87 x 10 pCi 5
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