ML20206G111

Ro:On 870320,operator Incorrectly Lowered Pulse Rod Receiver to Reduce Core Excess Reactivity.Caused by Human Error.Matl Re Problem Will Be Introduced Into Requalification Training Course

ML20206G111
Person / Time
Site:	General Atomics
Issue date:	04/07/1987
From:	Asmussen K GENERAL ATOMICS (FORMERLY GA TECHNOLOGIES, INC./GENER
To:	Harold Denton Office of Nuclear Reactor Regulation
References
38-1055, NUDOCS 8704140453
Download: ML20206G111 (2)

Text

._ - -- . - --- .__

d>

GATechnologies GA Technologies Inc.

PO. BOX 85608 SAN DIEGO. CAUFORNIA 92138 (619) 455-3000

! April 7, 1987 38-1055 Mr. Harold R. Denton Director Office of Mclear Reactor Regulation U.S. E clear Regulatory Commission j Washington, D.C. 20555

Reference:

Docket No. 50-89/163; License No. R-38

Dear Mr. Denton:

! On Monday, April 6,1987, the NRC Office of Region V was notified by telephrne of a reportable occurrence concerning the GA Technologies Inc. (CA) Mark I 'IRIGA reactor (R-38) . Details of the occurrence were presented at that time. Bis written report is being subnitted within j 10 days as required by the applicable Technical Specifications. %e details of the occurrence are presented below.

i on March 20,1987, at 1438, a senior reactor operator set up and

performed a pulse on GA's Mark I TRIGA reactor for a visiting tour group. In filling out the usual pulse stang data record, the operator discovered that the core excess reactivity was measured to be $3.33 which is above the $3.25 license limit set forth for pulsing in Section 7.2(b) of the Technical Specification. In an attempt to lower

. the core excess reactivity, the operator lowered the receiver for the pulse rod (thus reducing the length of the stroke of the pulse rod).

q Wis had the effect of reducing what would have been a $2.64 pulse to j a $2.54 pulse for the pulse actually performed, but left the core j excess reactivity at the original $3.33. The operator was under the impression that his action had reduced the core excess reactivity.

%e correct procedure for the operator would have been to secure the reactor prior to the pulse, remove one of the outer-most fuel elements and store it, and reneasure the core excess to assure that it was then less than $3.25.

On April 3, a senior staff member was reviewing the operations conducted during the previous few days when he discovered the above incorrect operation. Bis event was reported to Region V during the next working day.

It may be noted that the fundamental method to limit the size of the pulse is to assure that the transient rod is limited, as in this case l of the R-38 reactor, to no more than $3.00. For many years the 8704140453 87o4o7

{DR ADOCK 05000089 PDR IU933 aven om HOPKINS DR , SAN DIEGO. CAUFORNIA 92121 h[lIt b

r a

transient rod in this reactor has been worth about $2.75 or less. Now it is worth only about $2.65. Consequently, we cannot under any circumstances perform a pulse that now exceeds $2.65. 'Ihe requirement that the core excess not exceed $3.25 during pulsing operation is an additional safety requirement, but does not alter the fact that the pulse size is limited by the reactivity worth of the transient rod.

For carpleteness, the recorded pulse (No.11,097) produced a peak power of 695 m, the released energy was 15.8 Mf-sec, and the ==vi==

fuel tenperature was 4100C. All of these values are consistent for the $2.54 pulse.

As a corrective measure, the facility management will introduce material specific to the above problem into the requalification operator training course. In addition, a memorandtsu has been issued to all facility reactor operators calling attention to the above error in operator procedure.

If you have any questions concerning the above, you may call me at (619) 455-2823 or Dr. W. Whittemore at (619) 455-3277.

Very truly yours, Keith E. Asmussen, Manager Licensing, Safety and Nuclear Compliance KEA/mk cc: Mr. John B. Martin, NRC Region V

e transient rod in this reactor has been worth about $2.75 or less. Now it is worth only about $2.65. Consequently, we cannot under any circumstances perform a pulse that now exceeds $2.65. '1he requirement that the core excess not exceed $3.25 during pulsing operation is an additional safety requirenent, but does not alter the fact that the pulse size is limited by the reactivity worth of the transient rod.

For ccmipleteness, the recorded pulse (No.11,097) produced a peak I power of 695 m, the released energy was 15.8 Mf-sec, and the maximum fuel temperature was 4100C. All of these values are consistent for the $2.54 pulse, g As a corrective measure, the facility management will introduce material specific to the above problem into the requalification operator training course. In addition, a memorandum has been issued to all facility reactor operators calling attention to the above error in operator procedure.

If you have any questions concerning the above, you may call me at (619) 455-2823 or Dr. W. Whittemore at (619) 455-3277.

Very truly yours, Keith E. Asmussen, Manager Licensing, Safety and Nuclear Ccunpliance KEA/mk cc: Mr. John B. Martin, NRC Region V