ML20196B209

RO Update:On 981028,reactor Was Shutdown Upon Discovery That RB Ventilation Dampers Would Not Automatically Close.Damper Cylinder Was Repaired on 981102 & Reactor Operation Resumed on 981103

ML20196B209
Person / Time
Site:	University of Michigan
Issue date:	11/25/1998
From:	Jun Lee MICHIGAN, UNIV. OF, ANN ARBOR, MI
To:	Michaels T NRC (Affiliation Not Assigned)
References
NUDOCS 9812010016
Download: ML20196B209 (2)

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MICHIGAN MEMORIAL-PHOENIX PROJECT PHOENIX MEMORIAL LABORATORY FORD NUCLEAR REACTOR ANN ARBOR. MICHIGAN 48109 2100 November 25,1998 Theodore S. Michaels, Senior Project Manager U.S. Nuclear Regulatory Commission Non-Power Reactors and Decommissioning Project Directorate Division of Reactor Program Management Office of Nuclear Reactor Management Washington, D.C. 20555-0001 Docket 50-2, License R-28 Re: Notification of a Discovered System Deficiency - Failure of Reactor Building Ventilation Supply and Exhaust Dampers to Close

Dear Mr. Micheals:

This letter is a follow-up repon en the Ford Nuclear Reactor Ventilation Damper Cylinder problem that was initially reponed in a letter dated October 29,1998. The reactor was shutdown October 28 upon  :

discovery that the reactor building ventilation dampers would not automatically close. The damper '

cylinder was repaired on November 2 and reactor operation was resumed November 3.

The reactor building confinement system exists to minimize the release of radioactivity to the unrestricted area in the event of a major experiment or fuel element failure. The reactor building ventilation supply and exhaust dampers are a part of the confinement system. The dampers are designed to close automatically when the building alarm is actuated by abnormally high radiation levels detected in the reactor building exhaust air (> 1 mrem /hr), if the fuel vault criticality monitor alarms or by operator action.

The proper operation of the damper cylinder had been verified when the reactor control systems were checked out on October 20,1998, as required by technical specification 4.3.1. On October 28,1998 at approximately 10:30 a.m., the day shift operator discovered that the damper cylinder was sticky while performing a routine daily surveillance check. The Assistant Manager for Reactor Operations was mformed and promptly evaluated the situation. The evaluation determined that the damper cylinder was not just sticky, but was inoperable. The day shift lead operator, upon being informed of the inoperable damper cylinder, then began a reactor shutdown at i1:14 a.m.

s University of Michigan Plant Department personnel were called to work on the dampers. They disconnected the air cylinder, then removed and disassembled it. Inspection of the disassembled ilD I

components revealed that water, oil, rust and dirt had collected inside the cylinder. Some of this /

material was lodged in the cup seals of the air cylinder's piston thereby causing the piston to bind. The air cylinder itself was not the source of any of this material, since its internal surfaces were free of rust and corrosion.

O '20 The air cylinder components were all cleaned and lubricated. The air cylinder was then reassembled and reinstalled. Plant Department installed a new three-way solenoid control valve and a new in-line oiler as replacement parts. The ventilation damper controls were exercised. The dampers worked smoothly and normally after the repairs were completed. Basqd on the successful refurbishment, the Assistant Manager for Reactor Operatjons authorized reactor restart and operation resumed November 3.

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l The components and piping of the reactor air system consist primarily of carbon steel and the i L compressed air is somewhat moisture-laden. This results in some corrosion and loose mst particles which are carried through the system and can collect at trapping points such as the ventilation damper ait cylinder. The moisture prob em is currently addressed by periodically blowing down several traps at

. low points in the air piping.

In order to prevent a future recurrence of this problem, clean air will be supplied to the damper air j cyliiider. Plant Department suggested and FNR management agreed that an in-line air filter be installed.  ;

A modification request and supporting work order have been initiated to install an air filterjust before  ;

the damper air cylinder solenoid valve. Also, copper air lines will be installed between the air filter and

' damper air cylinder. This work is scheduled for the week of November 30.

Sincerely, i

i John C. Lee, Interim Director .

Michigan Memorial- Phoenix Project l l

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l xc: NRC Document Control Desk  ;

Tom Burdick, NRC '

SRC Members l

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