ML20062M105

Submits Addl Info on C/A for Reportable Occurrence 50-20/1993-1,operation W/Fewer than Required Number of 100 Kw Nuclear Safety Sys Level Channels.Existing dual-range Amplifiers Will Be Converted to low-range Only

ML20062M105
Person / Time
Site:	MIT Nuclear Research Reactor
Issue date:	12/28/1993
From:	Bernard J MASSACHUSETTS INSTITUTE OF TECHNOLOGY, CAMBRIDGE
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9401060130
Download: ML20062M105 (2)

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i  ;/h1 NUCLEAR REACTOR LABORATORY- -' '-

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- # ' AN INTERDEPARTMENTAL CENTER OF MASSACHUSETTS INSTITUTE OF TECHNOLOGY O. K. HARUNG 138 Albany Street, Cambodge, Mass. 02139 4296 J. A BERNARD,JR.

. Director - Telefax No. (617) 253 7300 Director of Reactor Operations Telex No. 92-1473-MIT-CA'A Tel. No. (617) 253-4202 December 28,1993 '

l U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Attn: Document Control Desk ~ U

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Subject:

' Additional Information on Corrective' Action for Reportable Occurrence 1 50-20/1993-1, Operation with Fewer than the Required Number.of <100 kW ~

~ Nuclear Safety System Level Channels .

Gentlemen:  ;

Item #9(iii) of the written report dated December 17, 1993 for Reportable Occurrence 50-20/1993-1 stated that. consideration would be given to modifying the existing low-range amplifiers so that they were no longer dual-range. This action would have two advantages. First,it would eliminate the need for a separate action to place the low-range amplifiers in the low-range ; mode subsequent to their installation. Second, the '  !

specially-designed connection that is at the front of each' amplifier could then be used to test all of the circuitry associated with each amplifier and removal of the input signal cable at the rear of each amplifier would be avoided. Thus, conversion of these amplifiers fmm dual-to low-range only would eliminate the need for corrective actions 9(i) and 9(ii) as stated in the written repon. This would be desirable because those actions were administrative in >

nature whereas conversion of the amplifiers is achieved via hardware. Moreover, removal

- of the input signal cable for testing risks damage to the amplifiers.

• On December 21, 1993, the MIT- Reactor Safeguards Committee reviewed ROR #1993-1 and approved the proposed modification. Accordingly, the corrective action z ~

s to address the root cause of ROR '#19931 will be to convert the existing dual.-range amplifiers to low-range only. This will be completed by January 21,1994. The actions -  ;

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' U.'S. Nuclear Reactor Commission i Page 2 listed under paragraphs 9(i) and 9(ii) of the written report will be continued on a temporary basis until the conversion is made. . However, they will not be permanently incorporated into the checklist governing reactor startup in the natural circulation mode. .

Sincerely,

,% Q b John A.' Bernard, Ph.D.

Director of Reactor Operations MIT Research Reactor

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J cc: USNRC- Pmject Manager, ,

NRR/ONDD ,

USNRC - Region 1 - Chief,. -

FRSSB/DRSS USNRC - Region 1 - Project Scientist, I

Effluents Radiation Protection Section (ERPS)

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