ML19309F088

RO 80-1:on 791009,during ECCS Tank TD-2 Monthly Flow Rate Verification,Flow Rate Observed to Be 8 Gpm.Caused by Loose Lock Nuts Which Fix handle-to-ball Operating Shaft. Surveillance Program Will Be Strengthened

ML19309F088
Person / Time
Site:	Neely Research Reactor
Issue date:	04/11/1980
From:	Kirkland R Neely Research Reactor, ATLANTA, GA
To:
References
NUDOCS 8004280477
Download: ML19309F088 (2)

Text

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t, GEORGI A INSTITUTE OF TECHNOLOGY ' ~

SCHOOL OF NUCLEAR ENGINEERING ATLANTA. GEORGI A 30332

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FR AN G M. MEE LY NUCLE AR RESE ARCM CENTER TE LE P6* DM E s (404) 894-3600 April 11, 1980 U.S. Nuclear Regulatory Comission, Region Ii 101 Marietta Street, N.W. Suite 3100 Atlanta, Georgia 30303 Gentlemen:

Reference:

Docket 50-160 License R-97

Subject:

Licensee Event Report IER 80-1 One of the Technical Specification Surveillance requirements for the Georgia Tech Research Reactor (GTRR) is a monthly flow rate verification from the Energency Core Cooling System (tCCS) tank TD-2. On October 9, 1979, during the performance of this test, the flow rate was observed to be 8.0 gallons per minute. 'Ihis is less tnan the operational lower limit of 8.3 gallons per minute.

'Ihe technique for measuring the flow rate is to initiate ECCS flew and note tank level readings versus time. 'Ihese data are then used with a tark cali-bration curve to determine the flow rate. On October 9, 1979, the test was performed and a flow rate of 8.0 gallons per minute (gpm) was noted by the reactor operator. 'Ihe test was repeated and the operator observed that the rate could apparently be varied from 8.0 to 8.5 gpm cepending on the manner in which ball-valve No. 94 was opened. valve 94 is a 1 1/2 inch, handle operated ball valve of stainless steel, type .116 with Teflon seat material.

A mechanical stop is installed to restrict the open position of the valve so that the desired flow rate can be obtained from the tank. 'Ihe operator

stated that he felt the flow variation was due to a looseness of the two 5 lock nuts fixing the handle to the ball operatire chaft. 'Ihe lock nuts were tightened. At this time a misunderstanding arose rt;sulting in the Reactor Supervisor believing that the problem had been corrected. She system was next checked on December 5, 1979 and subsequently on December 14, 1979, January 25, 1980 and February 11, 1980. In each case, the system flow rate

. was within the operational limit of 8.5 1 0.2 gpm.

During a reactor shutdown in March, valve 94 was closely re-exami ted. It was found that some looseness still existea between the handle and the ball operat-ing shaft because of clearance between the " flats" on the shaft and handle. AOO1 Shim material was installed to improve the fit between the two pieces. We (T have not been able to completely check this repair because the reactor is 5 l j

presently in a Mode 1 status and there is no water in the ECCS tank. . //g Even though the test made on Dece::ter 5,1979 and those subsequent to it wemg%

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. April 11,1900 satisfactory, we bel.ieve it may have been possible for the flow rate from the tank to be as low as 6.0 gpm at tires. he required miminum flow rate from the ECCS system is 8.0 gm as stated in our Safety Analysis Report (section 4.4.8.3, page 79). me operational limit of 8.510.2 gpa was chosen to provide some flexibility.

The following steps have been or will be taken to prevent a recurrence of an incident of this kind in the future.

1. Re-instruct all operating personnel in the necessity and requirement for fullow-up invest.igation and/or action when any reactor associated system coes not appear to be functioning norrally.

Status: Corpleted

2. Fill tank TD-2 with D 02 and thouroughly check the operation of valve 94 to assure ourselves of consistant, reliable operation.

Status: Not complete. Eis will be done as soon as additional D 20 is available to charge the process water system.

3 Strengthen our surveillance prograrl by establishing a second review of the surveillance documentation to be performed by a person of at least the level of plant knowledge of a senior reactor operator.

Status: h e second review has been put into effect.

Until item 2 above has been conpletec, the GTPR will not be operated at power levels greater than 1 Md.

Should you require any additional info: ration on this matter, please advise me.

Sincerely urs, Robert S. Kirkland Associate Director RSK:lzm cc: Menbers, Nuclear Safeguards Cam:ittee L.E. Weaver L.D. McDowell

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