ML20151X524
| ML20151X524 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 06/27/1977 |
| From: | Klingler G, Nolan F, Sniezek J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | |
| References | |
| PNO-77-114, NUDOCS 9809170134 | |
| Download: ML20151X524 (2) | |
Text
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.une 27, 1977 h$bW PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRE QU J
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ThispreliminarynotificationconstitutesEARLYnoticeofaneventofJ,k(4
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POSSIBLE safety or public interest significance. The information presented is as initially received without verification or evaluation and is basically all that is known by IE staff on this date.
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l Facil.ity: ' Sacramento Municipal Utility District (Rancho Seco)
Docket No. 50-312
SUBJECT:
UNPLANNED RELEASE OF AIRBORNE RADI0ACTI ITY 1
A licensee representative reported to the Region V (Walnut Creek, California) office the unplanned release of airborne radioactivity from the Rancho Seco plant at approximately 9:20 a.m. on June 24, 1977.
The release occurred when craft personnel of a contractor (Scott Co.)
were attempting to repair inward buckling (which occurred in February 1977) of the Reactor Coolant Drain Tank (RCDT).
During the repairs a previously closed isolation valve in a line which enters the tank was accidently cracked open allowing radioactive reactor makeup water to enter the tank. As a consequence, dissolved radioactive' gas was released to the Auxiliary Building and discharged to the environment through the Auxiliary Building Ventilation Stack.
The radioactive particulate monitor in the stack initiated an " alert" alarm 1
and a precautionary assembly of site personnel for evacuation was commenced i
in accordance with the facility emergency plan.
Personnel from the plant, staff successfully reclosed the valve within approximately 10 minutes, thus isolating the source of airborne radio-activity.
Site evacuation was secured at approximately 11:00 a.m.
Dosimeters worn by the craft personnel involved in the repair activity (three of whom were inside the RCDT) showed very low (less than 25 mrem)
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radiation exposure. Precautionary whole body counting of these individuals confirmed there had been no measurable internal deposition of radioactive material.
The licensee's preliminary evaluation showed that the airborne release to the environment was well within NRC limits.
Reactor operation was uninterrupted by the occurrence.
CONTINUE O
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I Page 2 PNO-77-114
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Continued June 27, 1977 l
A routine report of the occurrence was made to the local news media by the licensee.
A radiation specialist was dispatched to the site by the Region V office on June 24, 1977 to confirm the information reported by the licensee and evaluate corrective actions.taken to prevent recurrence.
A written re. port of the occurrence is to be submitted by the licensee in accordance with the facility license.
NRC Region V received initial notification of this occurrence by telephone from the Assistant Plant. Superintendent at approximately 12:15 p.m.
on June 24, 1977. This information is current as of 11:00 a.m. June 27, 1977.
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Contact:
GKlingler, IE x27451 FNolan, IE x27451 JSniezek, IE x27541 Distribution: Transmitted H St M/3E l
Chairman Rowden C. C. Xammerer, CA
'G. F. Murphy, JCAE Commissioner Kennedy S. J. Chilk, SECY H. H. Whiteside, SCNR j
Commissioner Gilinsky H. R. Myers, HCEE Transmitted: MNBB"JlDI P Bldg 1 l k SSBldgllYM L. V. Gossick, ED0~
E. G. Case, NRR C. V. Smith, HMSS I
S. H. Hanauer, EDO J. A. Harris, PA
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W. G. Mcdonald, MIPC Luge (MAIL E. Volge R. G. Ryan, OSP T. J. ETTe)rnan, OIA IE u, J YI l
Region 2
H. K. Shapar, ELD PRELIMINARY.Il0TIFICATION l
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