ML19308D522

RO-77-32:on 770404,while Reducing Power for Maint,Rod 6 of Group 7 Failed to Move.Caused by Control Rod Drive Mechanism Blown Fuse Due to Control Stator Failure.Stator & Fuse Renewed

ML19308D522
Person / Time
Site:	Crystal River
Issue date:	04/28/1977
From:	Stewart W FLORIDA POWER CORP.
To:
Shared Package
ML19308D521	List: ML19308D520 ML19308D522
References
NUDOCS 8002280961
Download: ML19308D522 (2)

Text

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LIC EN U kk kV E N i~ ILPUHT

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,1 CCNTROL ULOCK:l l l l l l l [PLCASS PntNT ALL RCouinED INTOlk.1AT:~

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[ 'ilAM' ucENsE NUMern "H#' Yv',"E e!'lclnlpl1l l 0 l 0 l-l 0 l 0 l 0 l 0 l 0 l-l 0 l 0 l l4 l 1 l1 l1 l1 l l0 l3 l 7 09 14 15 25 as 30 31 32 CAftcony "v7pf 3oM "

coexET NUMutR EVENT DATE REPCAT DATC 0 1 CONT l - l - l 7 0 57 50 W SS l Ll 60 l 0l 5l 0l-l 0 l 3l 0 l 2 l 61 68 l 0 l 4 l0 l4 l7 l7 l 69 74 l 0 l 4 l2 l8 l7 l7 75 UL

, EVENT DESCRIPTION O l Reducine newer for maintenance Rod 6. Crono 7 would not move contrary to Technical

• 7 09 6L EE l Soecifiestion 3.1. 3.1. C. There were no redundant systems available. First occurrence 7 89 -

at EE l of this ern e . System restored operable by renewing CRDM stator.

7 89 BC 03 l -' '  !

? U9 SC c l (1.ER-77-32) '

7 03 _ mg 6C.

cbcE cooE ccMPCNENT CCOE A VOLATON

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7 89 10 11 12 l Cl Rl Dl Rl Vl El 17 W43 44 lD l1l5l0l47 lN l 48 -

CAUSE DESCRIPTION

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@l 7 89 Failure of CRDM stator caused control fuse to blow making Rod 6, Group 7 inoperable. l GG hl 7 19 Maintenance restored Rod 6 operable prior 'to plan't startup. l 80 I '

l FAC&lTV METH00 CF STATUS  % POWER OTHER STATUS OtSCOVtAY CISCOVERY OESCRPf;GN 8

70 ID I 9

l0l4l1l12 13l 10 N/A l lAl l N/A l 44 45 46 CO AYENc3 07 f SE AMCUNT Of ACTMTY LOCATCN OF RELE4.SE 8

7 8 9 LzJ LzJ 10 l

11 N/A l 44 l

45 N/A l e0 PERSONNEL EXPOSURES NUMBER TYPE OLSCRIPTON 13 l0 l 010 l lzl l N/A l 7 89 11 12 13 00 PERSONNEL INJURIES NUMOCR CEScnrPTON h l0 l0 l0l11 12l 7 09 N/A l 00 OFFSITE CONSEQUENCCS 1

l N/A -

7 09 l UD LOSS On OAMAGE TO TACiUTY TYPE D .

@W 7 u9 l EECTtPTCN to N/A l

c0 PUOttC11y 3l

? O9 N/A j CU

- &10lTIONAL

' U3 See attachedFACTOn3 Supolementarv Information

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> vu - f NAuL:_ Wi P. Stewart .l rHONt: (813) AM _41 =o

SUPPLEMENTARY INFORMATION

1. Report No: 50-302/77-32

2. Facilitv: Crystal River Unit #3

3. Raport Date: 28 April 1977

4. Occurrence Date: 4 April 1977 -

5. Identification of Occurrence:

In the process of reducing power with Control Rod Group 7, Rod 6 of this group would not move contrary to Technical Specification 3.1.3.1.C.

6. Conditions Prior to Occurrence:

~

Plant was reducing power in Mode I.

7. Description of Occurrence: "

At 1055, while reducing power for planned maintenance, Rod 6 of Group 7 was found to be inoperable. Manual movement of Rod 6 was attempted with no success. Trouble-shooting revealed that the fuse controlling Rod 6 was blown. Further investigation revealed the stator for Rod 6 CRDM had failed. The plant was shut down and after maintenance, Rod 6, Group 7 demonstrated and declared operable.

8. Desianation of Apparent Cause of Occurrence _:

The primary cause of this event was the CRDM stator had failed which in '

turn caused this mechanism's fuse to blow, causing Rod 6 of Group 7 to become inoperable. l i

9.

1 Analysis of occurrence:

l There were no safety implications as the Reactor could have been safely shut down at any time.  ;

10. Corrective Action:  !

l The CRDM stator and control fuse were renewed and Rod 6 of Group 7 was l restored operable.

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11. Failure Data:

This occurrence was non-repetitive.

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