05000344/LER-1981-022, Forwards LER 81-022/03L-0.Detailed Event Analysis Encl

Forwards LER 81-022/03L-0.Detailed Event Analysis Encl

ML20031H168
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	10/16/1981
From:	Yundt C PORTLAND GENERAL ELECTRIC CO.
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20031H169	List: 05000344/LER-1981-022, Forwards LER 81-022/03L-0.Detailed Event Analysis Encl 05000344/LER-1981-022-03, /03L-0:on 810917,train a Was Inoperable Due to Suction Path from Control Room Being Isolated by Closed Manual Inlet Damper on Ventilation Sys.Caused by Loose Set Screw Allowing Operator to Be Moved W/O Moving Damper
References
CPY-793-81, NUDOCS 8110270213
Download: ML20031H168 (3)

LER-1981-022, Forwards LER 81-022/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3441981022R00 - NRC Website

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Portland General Electric Company q

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CPY-793-81 Mr. R. H. Engelken, Director Nuclear Regulatory Commission Region V 1450 Maria Lane Walnut Creek, California 94596-5368

Dear Sir:

In accordance with the Trojan Plant Operating License, Appendix A, US NRC Technical Specifications, Paragraph 6.9.1.9.b, attached is Licensee Event Report No. 81-22, concerning a situation where the manual inlet damper to the filter on Train "A" Control Room Emergency Ventilation System was found closed. Two independent trains are required to be operable in Modes 1-4 per Standard Tech-nical Specification 3.7.6.1.

The "B" train ventilation system was operable, therefore, impect on the plant was minimal. There was no effect on the public health or safety. This is a 30-day reportable occurrence.

Sincerely, G

C. P. Yundt General Manager CPY/MLD(LAW):na Att';hments c: LER Distribution List [hv

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hK03000344 23 011016"

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J REPORTABLE OCW RRENCE 1.

Report No.:

81-22 2.

a.

Report Date:

October 16, 1981 b.

Occurrence Date:

September 17, 1981 3.

Facility: Trojan Nuclear Plant, PO Box 439, Rainier, OR 97048 4.

Identification of Occurrence:

The manual filter inlet damper in the suction path from the Control Room to VC-142A was found completely closed. Closure of the damper isolated VC-142A which rendered "A" train of Control Room Emergency Ventilation System inoperable.

5.

Conditions Prior to Occurrence:

The plant was in Mode 1 at 100% power, steady-state operation.

6.

Description of Occurrence:

In reviewing data for the Control Room Emergency Ventilation Periodic Operating Test (POT-20-1), a Plant Engineer de" ermined that filter differential pressure was too low and began investigation as to why.

The manual filter inlet damper to VC-142A was found completely closed, although the operator for the damper was in the " locked open" positfon. Closure of the damper isolated VC-142A which rendered "A" train of Control Rcom Emergency Ventilation System inoperable.

7.

Designation of Apparent Cause of Occurrence:

The manual damper has an operating handle that attaches to the damper control cam by use of a setscrew. The setscrew had worked loose and allowed the handle to move semifreely, allowing false indication that the damper was open. Apparently, the damper was inadvertently closed by an operator when verifying the damper open per the procedure (POT-20-1), and the handle was then moved back to the open positiva but the damper remained closed.

8.

Analysis of Occurrence:

The setscrew attaching the operator to the damper was loose.

The torsional forces required to reopen the damper caused the setscrew to sl.p, allowing the operator to move without moving the damper.

This occurrence had no effect on the public health and safety nor on the habitability of the Control Room, since the "B" train was operable and no conditions requiring emergency ventilation system operation existed during the time the damper was closed.

9.

Corrective Action

The damper vaa opened and positioned to the proper position for the operator and the setscrew tightened to' reattach the operator to the damper.

POT-20-1 was run again to verify the operability of Train "A."

The system was declared operable after the 10-hour test was completed satisfactorily. Testing performed as a result of this occurrence has shown that the damper will not close due to air flow alone; it must be manually closed. Actual damper position is now verified monthly during performance of the surveillance test.

Additionally, the damper being closed results in low flow which is detected by low filter delta P.

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