ML20086D871

Ro:On 730205,all-purpose Fuel Grapple Became Detached from Jib Crane Hoist Cable When Tension Applied to Cable.Caused by Design Error.Grapple & Cable End Stud Reassembled,End Stud Drilled & Roll Pin Installed & Staked

ML20086D871
Person / Time
Site:	Vermont Yankee
Issue date:	03/06/1973
From:	Riley B VERMONT YANKEE NUCLEAR POWER CORP.
To:	US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086D869	List: ML20086D871
References
VYV-2479, NUDOCS 8312050206
Download: ML20086D871 (2)

Text

-

o O .

t' I

., - 9 VERMONT YANKEE N UCLEAR POWER CORPOR ATION '

SEVENTY GCVCN OROVF* CTRECT i

lttJTI.AND, VEltMONT OG701 FtEPLY TO:

VYV-2479 P. O. BOX 157 VERNON, VERMONT c5354 March;6, 1973 i

y 5%

I g

Director fE- 7 Directorate of Licensing United States Atomic Energy Commission

'" g \mSU C at? 411 Y

Washington, D.C. 20545

' OkET h

REFERENCE:

Operating License DPR-28 4

$ws p Docket No. 50.271 fu \ ' .-

Dear Sir:

During our recent fuel reconstitution an in. ident occurrel which we feel should be reported in accordance with Technical Specifications for the Vermont Yankee Nuclear Power Station, Section 6.7.C.

At 2124 on February 5,1973, the all-purpose fuel Frapple became detached f ron the jib crane hoist cable when tension was applied to the 4 cable. The grapple was attached to a fuel element at the_ time. The i fuel element was observed to remain seated in the fuel rack when the cable end stud pulled free of the grapple body. This incident attains i greater significance when viewed in the context of having been preceded by numerous fuel moves. The grapple was recovered and investigation revealed that the cable end stud was intact, its threads were undamaged, and that the locknut was present and could be threaded easily the length of the stud.

Q fl Additionally, it was observed that a. hole was provided in the side of the body of the grapple to permit installation or a pin but that a pin had

!j)- never, in f act, been installed nor was it ' called for by vendor drawing.

i ;It was concluded that the separation of stud and cable came about through

! g~  ; the repeated slight twisting of the cable ca~ sed by a 'non-symetrical rotation: '

!db i' of the all-purpose grapple during attachment and removal.

( fR)#

v3 The grapple and cable end stud were reassembled, the end stud drilled, and a roll pin installed and staked. The cable was inspected and nousigns

- Jf/ of deterioration were found.' The grapple assembly was then verified to be _

operable by lifting a fuel element under close observation while it remained in the storage rack.

s 8312050206 730329 Pg*y' i I PDR ADOCK 05000271 . -

l 5 PDR . .

1590-

F v .

'f * ( ( \,

, e b' VERMON[<dNKEE NUCl_ CAR POWER CORPORATION direc torate of Licensing March 6, 1973 Paf;c 2 The Plant Operations Review Comnittee concluded; that the installation of a roll pin in the grapple / cable end stud assembly will prevent recurrence of this problen, use of the jib innediately af ter repair was reasonable, and the future use of the jib crane to move fuel has been adequately safeguarded.

Very truly yours, VERMONT YANKEE NUCLEAR POWER CORPORATION k

B.U. Riley

3 Plant Superintendent hl TC / e 1, n.

4 9