05000455/LER-1990-008-10, :on 900929,fuel Assembly Dropped During Reconstitution Due to Procedural Inadequacy

:on 900929,fuel Assembly Dropped During Reconstitution Due to Procedural Inadequacy

ML20058E329
Person / Time
Site:	Byron
Issue date:	10/29/1990
From:	Pleniewicz R, Stauffer G COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
BYRON-90-1030, LER-90-008-10, LER-90-8-10, NUDOCS 9011070130
Download: ML20058E329 (5)

LER-1990-008, on 900929,fuel Assembly Dropped During Reconstitution Due to Procedural Inadequacy

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(viii) 10 CFR 50.73(a)(2)(x)
4551990008R10 - NRC Website

text

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Ccmm:nwealth Edis n Dyron Nuclear Station 4450 North German Church Road C

Byron,litanois 61010 October 76, 1990 t

Ltra DYRON 90-1030 i

U. S. Nuclear Regulatory Commit lon Document Control Desk Washington, D.C.

20555 Dent Sir The enclosed Licensee Event Report from Dyron Generating Station is being transmitt.ed to you in accordance with the requirements of 10CFR20.403(a)(4).

This report is number 90-000; Docket No. 50-455.

Sincerely, Jn R. Plenlewica Station Manager Dyron Nuclear Powe Station RP/m1m Enclosures Licensee Event Report No.90-000 cca A. Bert Davis, NRC Region III Administrator W. Kropp, HRC Senior Residt*t Inspector INPO Record Center CECO Distribution List f/

(0657R/0077R)

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ABSTRACT (timit to 1400 spaces, i.e. approximately fif teen single-space typewritten itnes) (16)

On September 29, 1990, at approximately 2130. Byron Unit Two was in a refueling outage with the tantor vessel defueled. Wettinghouse and f uel Handling personnel were performing bottom nor:1e fuel reconstitution activities in the spent fuel pool in preparation f or f uel reload.

Reconstitution of fuel assembly 177K had been completed after removing the indicated fuel rodlet and replacing it with a stainless steel dumy rodlet. The reconstitution basket lid was closed and the steps cere performed to secure the Ild in place prior to rotating the basket to the upright position.

nuring the rotation process, the f uel assembly slipped out of the basket and came to rest on the top o' en empsy fuel rack while remaining partially inserted in the reconstitution basket.

The assembly has been transferred to a failed fuel storage canister in the spent fuel pool. Procedural and work activity changes have been made.

This event was determined to be reportable in accordance with 10CFR20.403(a)(4).

(0657R/0077R/2)

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ptANT CONDITIONS PRIOR 10 EVENT:

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Refuelino Rx power. 0%.

RC$ (AB) Temperature /pressere.fD'r / 0 pSIG __

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On September 29, 1990, at approximately 2130, Byron Unit 2 was in a refueling outage with the reactor vessel defueled. Westinghouse and fuel Handling personnel were performing bottom nor:1e fuel reconstitution activities in the spent fuel pool in preparation for fuel reload. All refueling equipment was operable and functioning normally.

Reconstitution of fuel assemoly T77K had been completed af ter removing the indicated fuel rodlet and replacing it with a stainless steel dummy rodlet. The reconstitution basket lid was closed and the steps were performed to secure the lid in place prior to rotating the basket to the upright position. After the lid was closed, a J-hook lif t test was performed to determine if the lid could be physically lif ted to the open position as a final check prior to the rotation of the basket. After the J-hook test was successfully completed, the basket rotation step was initiated to restore the fuel assembly to the upright position.

During the rotstion process, the fuel assembly slipped out of the basket and came to rest on the top of an empty fuel rack while remaining partially inserted in the reconstitution basket. Westinghouse reconstitution personnel notified the Senior Reactor Operator present on the refueling floor.

The Westinghouse and Fuel Handling personnel stopped their activities and the Licensed Shift Supervisor for the plant was notified. Byron Abnormal Operating procedure 80A REFUEL 1. Fuel Handling Emergency. was entered. The Station Health physics personnel were cor,tacted to determine if any assembly fuel rodlets had suffered integrity damage. Based upon finding no detectable increase in radiation levels and no observable bubbling f rom the assembly, it was determined that no loss of integrity had occurred. The Nuclear Regulatory Coasnission Operations Center was notified of the event at 2220 using the Emergency Notifications system telephone network in accordance with 10CFR20.403(a)(4).

Subsequent recovery actions conducted by Westinghouse, Fuel Handling and Technical Staf f Nuclear Engineering personnel, in accordance with Special Test procedure SpP 90-69, returned the assembly to the reconstitution basket and rotated the basket back to the inverted position at approximately 0300 on 10/01/90. A visual inspection of the basket Ild and closure devices was performed to determine the cause l

of the lid opening. No failure or damage to the lid or closure device was apparent during the inspection.

l It was determined that the opening of the lid was caused by a failure of the closure device to be fully i

engaged and locked prior to the basket rotation.

l The assembly was later suspended f rom the $ pent Fuel pool Bridge Crane for inspection. The inspection revealed that the Number 2 Grid Strap on f ace Number 1 had sheared of f rendering the assembly unusable.

The assembly was then transferred to a failed fuel storage canister for long term storage.

(06$7R/0077R/3) l

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CAVILQLLY1MI:

The partial displacement of Fuel Assembly T77K from the reconstitution basket occurred when the reconsti-ution hasket bottom lid opened during basket rotation. Normally, lock pins on the lid pass through holes in the t,asket flange and are locked in place by swinging lock plates which physically

. restrain the lid pins. These lock plates are then subsequently pinned in place by lock screws to prevent them from disengaging the lid pins. The lid was later determined to be not fully closed which allowed the lock plates to be rotated into the lock position and the lock screws to be inserted without retiraining the lid pins, this allowed the lid to open when the basket was rotated to the upright position.

Additionally, the J-hook test (which was not contained in the Westinghouse procedure, but was routinely performed by their technicians) was performed to serify the lid was locked in place prior to the basket rotation, in this case, the J-hook test was faulted when the hook secured both the basket lid and the fuel assembly bottom nortle, thereby providing a false indication.

The root cause for this event is being attributed to procedural inadequacy. The Westinghosse fuel reconstitution procedure failed to provide adequate guidance to the Westinghouse technicians to allow them to ascertain the actual status of the reconstitution basket lid.

D.

$AFETY ANALY$1):

The damage to the assembly was limited to a grid strap which was sheared during the impact. Minor damage occurred in two of the empty spent fuel rack storage locations while no damage occurred to any other f uel assembly or component in the spent fuel pool. The dropping of a spent fuel assembly is bounded by the refueling accident analysis, which assumes that one fuel assembly is dropped onto another assembly, and is discussed in the Byron and Braidwood Updated Final Safety Analysis Report.

E.

LO!GLC11YLALIl0 tis The assembly has been transferred to a f ailed fuel storage canister in the spent fuel pool. The following procedural and work activity changes have been made to prevent recurrence:

1.

The Westinghouse procedure was rev; sed to perform an independent visual confinnation of the basket top and hottom lid hold down buttons (pins) as being latched and checked with a J-hook test prior to rotation of the basket.

2.

Additional steps were added to the Westinghouse procedure and checklist to provide guidance on how to close and secure the lid.

3.

Supervision of the crew was enhanced to ensure a Westinghouse supervisor is present at the reconstitution platform anytime the crew is performing any activity.

4 Westinghouse performed tailgating / training for the workers prior to resuming reconstitution activities. Olscussion included detatis of this event, corrective actions and normal performance of duties including procedural compilance.

in addition Byron Station has requested Westinghouse to review this event for 10CFR Part 21 appilcability and design adequacy. This is being tracked by Byron Action Item Record 455-225-90-22900.

(0657R/0077R/4)

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There have been no previous occurrences of dropped fuel assemblies during fuel reconstitution.

This esent is not reportable to NPRDS.

G.

(QM QNENT FAILURE DATA:

i There has not been a component f ailure identified as a result of this event.

(0657R/0077R/5)