ML19340B298

LER 80-024/03L-0:on 800914,during Core Unload,Fuel Bundle Was Removed While Source Range Monitor Was Reading Less than Min Required by Tech Specs.Caused by Misunderstanding of Recent Tech Spec Change

ML19340B298
Person / Time
Site:	Quad Cities
Issue date:	10/08/1980
From:	Knoespel P COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19340B294	List: ML19340B293 ML19340B298
References
LER-80-024-03L-03, LER-80-24-3L-3, NUDOCS 8010210760
Download: ML19340B298 (3)

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, EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h lT]Tl l During the Unit One End of Cycle 5 core unload, fuel bundle LJB429 was removed from l  ;

gl . core coordinate 37-48 while the SRM -in that quadrant was reading only 2.3 counts per l

,o,4, j second. This was. contrary to Technical Specification 3.10.B.2. which requires at 1 j g , -least 3 counts per second. There was no safety significance associated with this j t

,og,; event. The Northwest quadrant contained only three controlled as amblies and was  ;

neutronically-uncoupled f rcm the fuel remaining in the other three quadrants.

l0l7ll Criticality was not possible because analysis has indicated that an array of as many i j' i 0,8 ; l as 9 uncontrolled fuel assemblies will still-remain suberitical.  !

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ji;a,l The cause of this event was a misunderstanding of a recent change to Technical 1 s I li ! l : Specification 3.10.B. to which the Station had received verbal approval. The  ! l

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! ml personnel involved were instructed a's to the correct i n te rp re t'a t ion. In the future,- l l i I 31 I where practical, the use of changes to Technical Specifications, will be r'estricted l .j

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1. LER NUMBER: 'LER/RO-80-24/03L-0 ll. LICENSEE NAME: Commonwealth Edison Company Quad-Cities Nuclear Power Station

.ill. FACILITY-NAME: Unit One IV. DOCKET huMBER: 050-254 V. EVENT DESCRIPTION:

On September 14, 1980, during the Unit One End of Cycle 5 core unload, fuel bundle LJB429 was removed from core coordinate 37-48 whlle the SRM in that quadrant was reading only 2.3 counts per second. This was con-I trary to Technical Specification 3 10.B.2., which requires at least 3

! counts per second on the SRM during core alterations except when there l are no more than two fuel assemblies in that quadrant. Assembly LJB429

. was one of 3 bundles remaining in' the northwest quadrant at the time it was removed, and was diagonally adjacent to two assemblies around the SRM. The other three quadrants contained a total 'of approximately 50 assemblies with the corresponding SRMs reading more than 10 counts per second.

Technical Specification 3.10.B.2. had recently been changed to allow removal of=the last-two' assemblies in a quadrant with less'than 3 counts per second on - the SRM. The change had been approved by the NRC, but only verbal-approval had been received at'the Station at the time of the core unload.

On September 14, as the northwest quadrant was being unloaded, the Nuclear l

Engineer realized that none of the shift personnel had been informed of the Tech Spec change nor the verbal approval. The Shift Engineer placed a telephone call to the Operating Engineer. The Operating Engineer explained the change and its limitations to the Shift Engineer and the l Nuclear Engineer. The Shift Engineer then relayed.the explanation to the Reactor. Operator, also by phone. It was this explanation which was l misunderstood by the Reactor Operator, who then allowed the removal of l LJB429 which 'he thought was permissible under the' changed Technical Specification. The error.was realized before the unloading of the next quadrant was begun, and the core was unloaded with no further complications due to low SRM count rates.

VI. PROBABLE CONSEQUENCES OF THE OCCURRENCE:

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l The , reason for requiring 3 counts per second on the SRMs is to assure

.that'the reactor. core is adequately monitored during core alterations.

At the time that. LJB429 was removed from the core,~ the SRM in that quad-rant was reading 2.3 counts per.. second and 'had:been reading more than 4 counts'per second before the assembly immediately prior to LJB429 was L: unloaded. 'Thus, the SRM was functioning properly and did provide infor-i .mation on the status of.the core to the Reactor Operator. 'In addition, the SRMs in 'the other three quadrants were all" reading more than -10 H

counts perJ second and were available"to monitor the other areas of the

-Core.

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VI. PROBABLE CONSEQUENCES OF THE OCCURRENCE: (Continued)

General Elestric Company has indicated in the past . chat with any combination of fuel types used by Commonwealth Edison an array of as many as 9 uncontrolled fuel assemblies would still~ remain subcritical. Since the northwest quadrant contained only.3 controlled assemblies and was neutronically uncoupled from the fuel remaining in the other three quad-rants, criticality was not possible at the time the SRM count rate dropped to less than ; counts per second. There was, therefore, no safety significance is.ociated with this event.

Vll. CAUSE:

.The Reactor Operator allowed the removal of assembly LJB429 with fewer than 3 counts per second on the SRM tecause he misunderstood a recent

. change to Technical Specification 3.1).B. At the time of the core unload, the approved charge had not baen received at the Station in writing but verbal permission to unload the core utilizing the change had been received from the NRC. No written reference of the as-approved change was available to the shift personnel.

Vill. CORRECTIVE A,r. TION:

The immediate corrective action for this event was to inform the Reactor Operator of the correct interpretation of the new Technical Specification and of its limitations. In the future, where practical, the use of changes to the Technical Specifications will be restricted until either i the advance copy of the change, or the final printed copy is on site and is properly distributed.

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