ML19317D935

AO-269/74-16:on 741008,contents of a Gaseous Waste Decay Tank Released to Auxiliary Bldg During Increased Vent Header Pressure.Caused by Operation of a Gaseous Waste Compressor & B Gaseous Waste Decay Tank During Release

ML19317D935
Person / Time
Site:	Oconee
Issue date:	10/23/1974
From:	DUKE POWER CO.
To:
Shared Package
ML19317D926	List: ML19317D925 ML19317D935
References
NUDOCS 7912100611
Download: ML19317D935 (2)

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DUKE PC'.;ER CO:TANY OC05:2 U51T 1 Report Un.: A0-269/74-16 Report Date: October 23, 1974 gy Occurrence Date: October 8, 1974 Facility: Oconce Unit 1, Seneca, South Carolina .

Idcrei f ':., tion of Occurrence: Gascous waste release to the Auxiliary Building

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Conditions Pricr to Occurrence: Unit 1 at 30 percent full power, Unit 2 shutdoun Description of Occurrence: -

On October 8, 1974, Oconee Unit I reactor coolant system letdown flow to the "A" biced holdup tank resulted in increasing vent header pressure. The "A" gasects vaste cc pressor and the "B" gascous waste decay tank (GUD) were operating uhile the contents of the "A" GWD tank were being released.

At 2033, a hi;h yent header pressure alara (+2 inches H O) 2 was received and the control operator started the "B" unste gas ccapressor and stopped the reacter ;colant letdown f1cu to decrease vent header pressure. Vent header pressure immediate?y returned to normal. At 2040 the Unit 2 vent gas radiation conitors 22IA-45 and 2RIA-46 alarmed and the auxiliary and turbine building exhaust fans were stopped. Further radiation monitors alarmed in the auxiliary building and the Unit 1 vent. The "B" gaseous waste compressor was stopped.

Health physics personnel sampled the Unit 2 vent, auxiliary building hallway and the gaseous waste compressor room. The release frca the "A" GND tank uas stopped, and a negative pressure was established on the vent header.

At 2130, Operations personnel entered the auxiliary building with respiratory protection, made visual inspections, and placed the "A" Gi!D tank in service and isolated the "S" tank. At 2204, the auxiliary building fans were started and the Unit 1 and 2 vent alarns cleared. At 2310, health physics personnel cicared the auxiliary building for entry. At 2315, it was discovered that an instrbrent line for the "3" gaseous vaste separator tank unloading valve was disconnected. The loose tubing was reconnected and the co= pressor was tagged out until it could be checked.

Designation of Accarent Cause of Occurrence:

A station =odificatien was perforced during the day shift on October 8, 1974 to both "A" and "B" wasrc gas compressors.

The vibration on the waste gas compressors was causing execesive wear on the unloading valve (C'. D-78 and 79) controllers. The modification =oved the controllers to the wall behind the po oo 6/

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corpressors and utiliced an existing tubing tray for rerouting the instrument piping. Apparently, the piping ces not fully eennected, and when the "B" was startcJ, the contents of the "B" GWD tank

. gaseous waste ccepre cor captied to the auxiliary building. '

Ana lynis of Occurrencei Oconce Nuclear Statien Technical Specification 3.10, "nelcase of Gaseous Radioactive h'aste," provides objective limits as to the quantities of radio-active gas which may be released. In this instance, the quantities of gas released can be calculated based upon the decrease in pressure in the "B" GUD tank during the release and the known activity at the' beginning of the release.

The total gaseous activity release,d was 25.8 Ci which was 0.05_gercent of the annual objective limit. The total f odine released was 2.377 x 10 Ci which was 0.06 percent of the annual objective limit. The maximum release rate averaged over a one-hour period was not exceeded and personnel on site did not receive any significant radiation exposure. The health and safety of the public was not affected.

Corrective Action:

A meeting was held on October 15, 1974 with the station Manager and all supervisors which stressed the necessity for attention to detail and completeness in any maintenance activa.

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