ML20028A308

Forwards LER 82-042/03L-0.Detailed Event Analysis Encl

ML20028A308
Person / Time
Site:	Fort Saint Vrain
Issue date:	11/10/1982
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20028A309	List: ML20028A308 ML20028A310
References
P-82515, NUDOCS 8211180220
Download: ML20028A308 (5)

Text

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public servlee company e Odonde 7 . 16805 Road 19 1/2, Platteville, Colorado 80651-9298 November 10, 1982 Fort St. Vrain Unit No. 1 P-82515 k

L> n r 9 15I982 Mr. John T. Collins, Regional Administrator dL

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Region IV j Nuclear Regulatory Commission '--

611 Ryan P ~iaza Drive Suite 1000 Arlington, Texas 76011

Reference:

Facility Operating License No. DPR-34 Docket No. 50-267

Dear Mr. Collins:

Enclosed please find a copy of Reportable Occurrence Report No. 50-267/82-042, Final, submitted per the requirements of Technical Specification AC 7.5.2(b)4.

Also, please find enclosed one copy of the Licensee Event Report for Reportable Occurrence Report No. 50-267/82-042.

Verprulyyours, Abit r Don Warembourg Manager, Nuclear Production DW/cis Enclosure , gh cc: Director, MIPC M ,

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- PDR ADOCK 05000267 S PDR

REPORT DATE: __ November 10, 1982 REPORTABLE OCCURRENCE 82-042 ISSUE O OCCURRENCE DATE: October 13, 1982 Page 1 of 4 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD COUNTY ROAD 19 1/2 PLATTEVILLE, COLORADO 80651-9298 REPORT NO. 50-267/82-042/03-L-0 Final IDENTIFICATION OF OCCURRENCE:

On October 13, 1982, with the reactor shutdown, an unsampled, unplanned, radioactive gaseous release to the atmosphere took place.

The source of the gaseous effluent was a leak within the Reactor Building which was exhausted to the atmosphere via the filtered ventilation exhaust stack. The release to the atmosphere was less than maximum permissible concentration. This event constitutes a degraded mode of LCO 4.8.1, and is being reported per AC 7.5.2(b)4 of the Fort St. Vrain Technical Specifications. -

EVENT DESCRIPTION:

On October 13, 1982, the reactor was shutdown and depressurized for various core maintenance activities. One of these activities was the removal and repair of HV-2301 (helium purification train "A" inlet valve). Upon removal of the valve, blank flanges were installed on both the upstream (PCRV) and downstream (purification train) sections of remaining pipe. These flanges were installed utilizing standard conical type seals.

At 0555 hours0.00642 days <br />0.154 hours <br />9.176587e-4 weeks <br />2.111775e-4 months <br />, a high airborne activity monitor alarmed in the Reactor Building. The building was evacuated per station emergency procedures. The high airborne activity in the Reactor Building was exhausted to the atmosphere via the monitored and filtered ventilation exhaust stack. The exhaust stack radiation monitors (RIS-7324-1 and RIS-7324-2) showed a slight increase, but levels never exceeded maximum permissible concentrations. The total release was calculated to contain 0.78 curies of noble gas (primarily Xenon-133).

Upon investigation of the source of airborne gaseous activity, it was found that the blank flange (on the purification side of where HV-2301 was removed) had a leaking seal (See Figure 1). The source of activity was the helit.m being used to regenerate that purification train's dryer. During dryer regeneration, that particular flange was subjected to approximately 88 psig pressure. '

REPORTABLE OCCURRENCE 82-042 ISSilE O Page 2 of 4 1

CAUSE DESCRIPTION:

The seal between a blank flange and the purification train "A", where HV-2301 was removed, failed. This failure allowed helium being used to regenerate the train's dryer to escape to the Reactor Building.

The associated activity was then exhausted via the filtered Reactor Building exhaust stack to the atmosphere.

CORRECTIVE .

ACTION:

Upon receiving the high airborne activity within the Reactor Building, the building was evacuated per Emergency Procedures.

Emergency Procedures were initiated to determine the extent and contents of the atmospheric release. The unplanned release constituted an " Unusual Event," and proper notification was made to Federal and State authorities.

Regeneration of the purification train "A" dryer was stepped.

When accessible, a new seal was installed on the blank flange which was found to be leaking. The associated secondary cover was replaced on the well where HV-2301 is normally located, until the valve could be re-installed in the system.

No further corrective action is anticipated or required.

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Inlet of Train A Puri fication

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Sys tem llelium Puri fication Fil ter/ Absorber) Dryer

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Blank flange and gasket where leak (f

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Continuation to Outlet A-2303. of Train A

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Figure 1: Simplifled Section of flelium Purification System

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REPORTABLE OCCURRENCE 82-042 ISSUE O Page 4 of 4 4

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Prepared By: a o.a s A. -vlwC OwenJ.Clakton Q Senior TechAical Services Technician Reviewed By: A Charles Fuller du  :

Technical Services En ine ng Supervisor s

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Reviewed By: /' f EdwinDJatiylf" Station Manager i

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Approved By: / f/ff>/ #'

DoW Waremb6urg ~ ~

i Manager, Nuclear Prod ion i

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