ML19308D424

RO-77-43:on 770427,regulatory Rods Group 7 Found Out of Specified Limits.Caused by Grounded Connector Shield in 24 Volt Programmer.Connector Repaired & Further Investigation Underway

ML19308D424
Person / Time
Site:	Crystal River
Issue date:	05/17/1977
From:	Stewart W FLORIDA POWER CORP.
To:
Shared Package
ML19308D401	List: ML19308D400 ML19308D424
References
NUDOCS 8002280728
Download: ML19308D424 (2)

Text

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@l 7 09 In Mode 1 ope ration, Control Rod Group 7 dropped into the core on two occas' ions caus'ing

" ti 0 l the overlap between Croup 6 and 7 to be less than 25% contrary to Technical Specification 7 n0

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3.1.3.6. Redundancy N/A. First and second occurrence of this type. On both occasions.

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0 l 7 u9 the croun was retrieved and the overino adiusted to within -

the soecified if mits in the G.

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7 0U (LER 77-43) pauE bs SYSifM CAUSE COMIONENT CODE COMPONENT CODE. COMPONENT CooE SUPPleA MANUFACTUACR VOLAtON

@ l Rl Bl lE l 7 09 10 l Cl Rl Dl Rl Vl El lNl lD l 1l 5 l 0 l lN l l 11 12 17 43 44 47 48 CAUSE DESCRIPTION 0 Ql 7 a9 The cause of these occurrences appears to have been a grounded shield in a connector Ql 7 H9 to the 24 volt program:ner that was not identified until after the second occurrence.

bi Gi C* The connector was repaired, clearing the ground and restoring the system operable.

F AJiln Y METHoo oF STATUS . % POWER oTHEn STATUS otSCovEnY Q

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PERSONNEL EXPOSunES NUMDEA TYPE DESCAiPTON  ;

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OFFSITE CONSEOUENCES 1

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f SUPPLEMENTARY INFORMATION

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1. Report No: 50-302/77-43 .

2. Facility: Crystal River Unit #3

3. Report Date: 17 May 1977

4. Occurrence Date: 27 April 1977

5. Identification of occurrence:

Regulating rods Group 7 out of specified limits contrary to Technical Specification 3.1. 3.6.

6. Conditions Prior to Occurrence:

Normal Mode 1 steady state operation.

7. Description of Occurrence:

i.

On two occasions, 0417 and 1020, regulating rods Group 7 dropped into the core causing the overlap between Group 6 and 7 to be less than the required ' overlap of 25%. On the first occasion, Group 7 automatically withdrew and the overlap was manually adjusted to the specified limit within the allowed time frame. The second occasion, Group 7 was re-latched and the overlap was manually adjusted to the specified limit s_ in 50 minutes.

, 8. Designation of Apparent Cause of Occurrence:

The first occasion was investigated and no cause was determined. On the'second occasion, further investigation revealed a grounded connector shield in the 24 volt programmer.

9. Analysis of Occurrence:

At no time during these two occurrences was the safety of the general public affected.

10. Corrective Action:

i The connector in the 24 volt programmer was repaired. This was thought to have been the corrective action solution, however, a 'similar event occurred on 13 May 1977. Investigation into this problem is underway.

The latest occurrence will be reported when further information can be obtained.

11. Failure Data:

These were the first and second occurrences of this type.

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