ML20236T222

Ro:On 871030,deputy physicist-in-charge (DPIC) Bypassed Cylinder Down Limit Microswitch & Failed to Check Action of Interlock Sys When Checking Operation of Maintained Control Transient Rod.Maint Overhaul on Sys Ordered & DPIC Rebuked

ML20236T222
Person / Time
Site:	General Atomics
Issue date:	11/06/1987
From:	Asmussen K GENERAL ATOMICS (FORMERLY GA TECHNOLOGIES, INC./GENER
To:	Harold Denton Office of Nuclear Reactor Regulation
References
38-1143, NUDOCS 8712010083
Download: ML20236T222 (3)

Text

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- GATechnologies 7 am

• l l G A Technologies Inc.

PO. BOX 85600 l SAN DIEGO. CAUFORNIA 92138 l (619) 455-3000 November 6, 1987 38-1143 Mr. Harold R. Denton, Director Office of Ibclear Reactor Regulation U.S. !belear Regulatory Cmmission Washington, D.C. 20555 Reference Docket No. 50-89/163: Reactor Facility License No. R Reportable Occurrence

Dear Mr. Denton:

On Monday, November 2,1987, the NRC Office of Region V was notified by telephcne of a reportable occurrence concerning the GA Technologies Inc. (GA) Mark I TRIGA reactor '.R-38) . Details of the occurrence were presented at that time. This written report is being subnitted within 10 days as required by the applicable Technical Specifications. 'Ihe details of the occurrence are presented below.

Secuence of Events gy On Friday, October 20, 1987, following cmpletion of the required daily start-up checks, a senior operator started to conduct a series of runs for reactor custmers. When he attempted to start the first of these runs at about 0820, he fota.3 it impossible to maintain air pressure on the transient rod piston. As a consequence, he could not withdraw the central transient rod (CTR) to its full out position, which is the first step in starting up the reactor. He sought the help of the Deputy Physicist-in-Charge (DPIC) who then initiated a series of microswitch adjustments to attempt to correct the situation. ,

when this proved unsuccessful, the DPIC reasoned that he could bypass the C'IR Air Limit microswitch without interfering with the license required interlocks. After making the temporary bypass, he and the senior operator at the cmsole performed checks to assure that the safety system was still functional. Having satisfied himself that the maintenance was adequate, the DPIC made a proper entry in the Maintenance Log Book and declared the reactor operational.

Subsequently, six steady-state runs and one pulsed operation were conducted during the reainder of the day (until about 1325) and then the reactor was shutdown.

At 2200 on the same day (October 30, 1987) another senior reactor operator was performing the routine weekly checkout of the reactor system when he discovered that air could be applied to the transient py .I D

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rod regardless of the position of its cylinder. This is in violation of the interlock requirement set forth in the Technical Specifications in Table II, Item 3 which states that in steady state this interlock will prevent the a); plication of air to the transient rod unless its mweable' cylinder is fully down. He promptly notified the facility management and received instruction to reove the temporary bypass installed earlier that day by the DPIC and secure the reactor until the following Monday morning.

Discussion We reportable occurrence arose because of two errors on the part of the DPIC. First he mistook the Cylinder.DOWN LIMIT microswitch (which is in the interlock circuit) for the Cm AIR LIMIT microswitch which is not part of the interlock circuit. When the Cylinder DONN LIMIT microswitch was bypassed, air could be applied to the transient rod with the cylinder in any position.  % e second error by the DPIC was ,

the failure to check this specific action of the interlock system when he was checking the operation of the maintained control transient rod.

It is very important to note that the method of operation at the TRIGA Facility is such that no safety issues were raised by the bypass of the. cylinder DOWN LIMIT microswitch. This is because the first action of every start-up in steady state is to withdraw fully the transient rod while all other control rods are full down. An experienced Senior Reactor Operator conducted all the runs on the day in question and did in fact follow this procedure. We only deviation fran this procedure was that for the one pulsed operation on October 30. In this operation, it was of course the intent to apply air to the transient rod cylinder and fully withdraw the rod when the reactor was critical at low power (< 1 kw) .

Agtion Taken (1) On Monday, November 2,1987, the Facility management ordered a complete maintenance overhaul of the transient control rod drive system. This included acticns that were planned for the routine annual inspection that occurs in December each year. m is year, those activities will be conducted a month early. We drive systen will be overhauled on the shop bench with all worn or damaged microswitches to be replaced. When all maintenance work has been completed and the drive assenbly has been reinstalled, a complete check of all related safety functions will be conducted as per section 5.3 of the Technical Specifications.

(2) Since the safety checks conducted by, or under the supervision of, the DPIC were inconglete as per Section 5.3, he has been seriously rebuked. After consi& rable discussion, more serious disciplinary action was deemed unnecessary because the DPIC is a very senior and experienced reactor operator with nearly twenty years of experience

rc lj [, s e

at this facility.

His - duty is to maintain .and. ' repair most

. whanical and electrical items and to fabricate:and install most

= new experiments conducted on the reactors. All of' his past performance has demonstrated a careful regard for all aspects of I .

safety. In this light, we- judge' our corrective action to, be'

!< proper.-

If you should have questions on the above reportable occurrence,

' please' contact me at' (619) 455-2823 or Dr. W. Whittemore at the 'IRIGA Facility, (619) -455-3277.

Very truly yours, M c=W Keith E..Asmussen,. Manager i: Licensing, Safety and Nuclear Compliance

- hDf/bb

- oc: Mr. John B. Martin, NRC, Region V

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