ML20085B598

Telecopy of Ao:On 720507,bolt Discovered in Steam Generator 2.Caused by Accident During Shipment.Review Conducted.Failed Bolt Determined to Be from Compensating Ring Shim.Operation Will Restart on 720517

ML20085B598
Person / Time
Site:	Palisades
Issue date:	05/15/1972
From:	Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	Block E US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085B488	List: ML20085B498 ML20085B513 ML20085B521 ML20085B527 ML20085B575 ML20085B598
References
NUDOCS 8307080213
Download: ML20085B598 (3)

Text

kGMCGBA CGO 1-012592A136 05/15/72 g 0 P UPL ATE mesWn union 003 JACKSON MICH O ZIP 60137 g O #

Q 60YCE H GRIEH DIVISION OF COMPLIANCE CHICAGO OPERATIONS OFFICE O USAEC g GLENN ELLYN, ILLINDIS 60137 O #

'O #

O O CONSUMERS POWEH COMPANY r Q PAdNALL ROAD OFFICE g

JACKSON, MICHIGAN '

c 5-15-72 T0- MR E J BLOCK, DIRECTOR '

DIRECT 03 ATE OF LICENSING t- 'a O UNITED STATES ATOMIC ENERGY COMMISSION a '

g WASHINGTON, DC '

O R E- DOCKET 50-255 --

~

g LICENSE DPR-20 Q DURING AN INSPECTION OF THE INLET PLENUM OF THE PRIMARY SIDE OF THE g NO 2 STEAM GENEHATOR AT THE PALISADES PLANT ON MAY 7,1972, A PORTION OF A BOLT WAS DISCOVERED. AT THE TIME THE PORTION OF THE BOLT WAS O FOUND, THE PLANT WAS IN A COLD SHUTDOWN CONDITION DURING AN OUTAGE g SCHEDULED TO CONDUCT BOTH PRIMARY AND SECONDARY SYSTEM MAINTENANCE.

O THE BOLT WAS THE PORTION ABCVE THE THREADS OF A 5-8 INCH DIAMATER g SHOULDER BOLT. A DETAILED REVIEW YIELDED THAT THE ONLY PRIMARY SYSTEM COMPONENT UTILIZING A 5/8 INCH SHOULDER BOLT IS THE COMPENSAT-O ING RING SHIM (A PORTION OF THE UPPER GUIDE STRUCTURE). THE MARK- g INGS ON THE SOLT IDENTIFIED THE BOLT TYPE AND BOLT MANUFACTURER. THE MANUFACTURER OF THE REACTOR INTERNALS CONFIRMED THAT THIS TYPE OF Q BOLT HAD BEEN USED. g WE BELIEVE THE CAUSE OF THE FAILURE OF THIS COMPENSATING RING SHIM Q BOLT STARTED WITH AN ACCIDENT DURING SHIPMENT OF THE UPPER GUIDE g STR UCTUR E. IN THIS ACCIDENT, THE UPPER GUIDE STRUCTURE AND THE COM-PENSATING RING SHIM WERE STRUCK RADIALLY. WHILE THE IMPACT WAS NOT Q CONFIRMED SUFFICIENT TO SEVER THE BOLT (INSPECTIONS SUBSEQUENT TO THE ACCIDENT THIS), IT COULD HAVE CAUSED DEFORMATION TO THE SHOULDER $

SECTION AND INITIATED A CRACK AT THE ROOT OF THE UPPER THREAD. THE O INSPECTIONS PERFORMED SUBSEQUENT TO THE ACCIDENT WOULD NOT HAVE DE- g TECTED A CHACK AND SHOULDER DEFORMATION. DURING NO AL HEATUP AND O - -

• # l887288Ef d a dj"gg 2 74 e

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O PAGE 2 Q

O EHL ailgram .

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C00LDOWN CYCLES, THE FORCE OF THE RING SHIM DUE TO DIFFERENTIAL O EXPANSION AGAINST THE SHOULDER BOLT INTRODUCED SUFFICIENT LOADING g) 1 IN THE ALHEADY WEAKENED BOLT WHICH EVENTUALLY RESULTED IN ITS l FAI LUR E. 1 O

THIS BOLT WAS ONE OF EIGHT BOLTS INSTALLED TO HOLD THE RING SHIM IN el PLACE ON THE UPPER GUIDE STRUCTURE FLANGE DURING SHIPPING AND REFUEL- 1 O ING OPERATIONS. THESE BOLTS ARE NOT REQUIRED DURING REACTOR OPERA- gl TIONS. '

O SHoutD FuaTHER BOLTS FAIL UNDER FULL FLOW CONDITIONS, THE BOLTS WOULD gl BE CARRIED BY THE FLOW STREAM DOWN THROUGH THE UPPER GUIDE STRUCTURE l AND THE CORE BARREL AND PASSES OUT THROUGH THE OUTLET N0ZZLES INTO A J

_O STEAM GENERATOR. THE HEAD OF THE BOLT PREVENTS ITS PASSAGE THROUGH g' THE STEAM GENEHATOR.

O UNDER PARTI AL FLOW OR IF THE FLOW WERE SHUT OFF WITH A BOLT IN g TRANSIT TO THE OUTLET N0ZZLES, THE BOLT COULD DROP DOWN AND REST ON THE TOP OF THE CORE SHROUD OR THE TOP OF FUEL ASSEMBLIES. IT IS O POSSIdLE THAT A BOLT COULD DROP DOWN BETWEEN AN OPENING IN THE CORE gl SHROUD LATEHAL SUPPORT PLATES AND LIE TRAPPED BETWEEN THE CORE SHROUD AND CORE BAdREL. IN NO CASE COULD A BOLT DROP BELOW THE TOP PLATE ]

O OF A FUEL ASSEMBLY IN THE CORE REGION BECAUSE THERE ARE NO OPENINGS g' LANGE ENOUGH TO PERMIT PASSAGE OF A 5/8 INCH SHOULDER BOLT.

O ASSUMING A BOLT WAS TO REACH THE TOP OF THE FUEL ASSEMBLY, IT IS g POSSIBLE UNDER NO FLOW CONDITIONS THE BOLT MIGHT HOLL PAST THE POST AND GUIDE ROD NUT OF A FUEL ASSEMBLY IF THE ADJACENT CONTROL BLADE O WERE FULLY INSENTED. IT MIGHT COME TO REST BETWEEN THE TOP OF THE g CONTROL BLADE AND THE BOTTOM OF THE LOWER END OF THE CONTROL SHROUD.

THIS COULD CAUSE INTERFERENCE WITH THE CONTROL BLADE WHEN WITHDRAWAL j Q WAS ATTEMPTED. WHEN FLOW IS RESTARTED, THE BOLT WOULD BE CARRIED g 007 0F THE REACTOR INTO THE STEAM GENERATOR. OUR REVIEW YIELDED THAT THIS WAS THE ONLY CASE IN WHICH THIS TYPE OF BOLT FAILURE COULD CAUSE O INTEaFEHENCE WITH A CONTROL ROD DRIVE MECHANISM. g uASED ON THE INSPECTIONS OF THE BOLT AND THE STEAM GENERATOR, WE O WOULD NOT EXPECT ANY DAMAGE TO THE STEAM GENERATORS IF FURTHER FAIL- g URES WEHE TO OCCUR. THE BOLT EXHIBITED ALMOST NO EVIDENCE OF TUMB-LING AND HAD OBVIOUSLY BEEN INACTIVE IN THE STEAM GENERATOR HEAD.

BASED ON THE APPARENT CAUSE OF THE BOLT FAILURE AND THE NONDETRINEN-TAL EFFECT UPON INTERNALS FUNCTIONING OR REACTOR OPERATIONS OF O FURTHER OCCURRENCES, WE PLANT TO RETURN THE PLAXX PALISADES PLANT TO g SERVICE ABOUT MAY 17, 1972. DURING THE NEXT REFUELING OUTAGE, A MODIFICATION WILL BE MADE THAT WILL PREVENT ESCAPE OF THE UPPER PORTIONX OX #

l PORTION OF A FAILED BOLT FROM THE COMPENSATING RING SHIM.

O WE WILL SUBMIT FURTHER DETAILS BY LETTER WITHIN THE NEXT TWO DAYS. g NALPH B SEWELL l

O NUCLEAR LICENSING ADMINISTRATOR

$g J Y g

! CONSUMEHS POWER COMPANY ,

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Q O f e i

O O PAGE'3 Q

O M8 .i. Mailgram ei O .

CC- BOYCE H GRIE11 Q USAEC $

GLENN ELLYN, ILL O caw e Q 1627 EST $

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