ML19345G129
| ML19345G129 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 03/12/1973 |
| From: | Searls F PACIFIC GAS & ELECTRIC CO. |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| 1775, NUDOCS 8103020685 | |
| Download: ML19345G129 (2) | |
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PACIFIC GAS AND E LE C T RIC C O M PANY bbW3 l
77 BEALE STREET
- SAN F R A N CISCO, C ALIFO R N I A 94106 *(415) 781-4211
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March 12, 1973
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Attention:
- Director, Directorate of Licensing Re:
Docket No. 50-133 License No. DPR-7 Humboldt Bay Power Plant Gentlemen:
As a matter of information, we are hereby informing you of a minor, unplanned release of liquid radwaste to the discharge canal from Unit No. 3 of Humboldt Bay Power Plant on January 26, 1973.
This occurrence was discussed with Mr. A. D. Johnson of the Region V Regulatory Operations office on that date.
The quantity and types of radioactivity released were similar to those for planned releases, and the concentration of radioactivity released was well below any reportable level specified in 10 CF.'t 20.
The release occurred when a manual, remotely operated valve from the radwaste concentrator to the No. 2 concentrated waste tank unintentionally was left partially open allowing the tank, which had been filled in a previous operation, to overflow onto the floor of the tank.
The vault drain to the radwaste sump had been plugged with debris.
As a result, the vault filled to a level of approximately two foot allowing some solution to flow along the annular spaces between the concrete and the instrument penetrations in the west wall of the vault, which are at that eleva-tion.
This water then entered an outside drail:, which can be valved either to the radwaste sump or to the dischargs canal, but at that time was valved to the canal.
As soon as the leakage was discovered the drain was valved to the radwaste sump, the cause of the leakage was determined, and the valve from the concentrator to the No. 2 concentrated waste tank was closed.
The vault was pumped to the No. 3 waste receiver tank, and then the vault drain was unplugged.
The floor area near the outside drain was cleaned and repainted to l
fix the residual contamination.
The instrument penetrations through which the water leaked were recaulked.
y l msome P00R ORIGINAL m{
g U. S. Atomic Energy Commission March 12, 1973 Attn.:
Director, Directorate of Licensing Page 2 The investigation of this occurrence consisted of the fol-lowing:
measuring Ehe radioactivity concentration of the No. 2 con-centrated waste tank, the water in the vault, and the water on the floor around the drain Which was valved to the canal; estimating the amount of water that leaked to the canal by defining the maximum length of time water could have leaked from the vault (operator's observations on routine rounds) and estimating leakage rate (operator's observations); collecting the intake and discharge canal composite samples Which had been accumulating since January 24, 1973; and analyzing the above data.
The analysis of the above data permitted calculation of the total activity released by two different methods.
It is conservatively es centrationof3.8x10-pimatedthat50gallonsofwater,withacon-nC1/ml, were released to the canal.
This resulted in concentrations in the plant outfall canal Which were well below any reportable limits specified in 10 CFR 20 and less than the State of California North Coast Regional Water Quality Control Board Ibnit of 1 x 10-6 pCi/ml When measured over any period of seven con-secutive days.
Very truly yours, rr g- / f CC:
Mr. R. W.
Smith i
Direct t l
Directorate of Regulatory Operations Region V U. S. Atomic Energy Commission 2111 Bancroft Way Berkeley, California 94704 l
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