ML19308D395

RO-77-44:on 770427,regulating Rod Insertion Limits Exceeded. Caused by Xenon Buildup & Group 7 Being Fully Inserted. Personnel Instructed to Monitor Rod Index Limits More Closely

ML19308D395
Person / Time
Site:	Crystal River
Issue date:	05/18/1977
From:	Stewart W FLORIDA POWER CORP.
To:
Shared Package
ML19308D394	List: ML19308D393 ML19308D395
References
NUDOCS 8002280706
Download: ML19308D395 (3)

Text

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1. Report No: 50-302/77-44

2. Facility: Crystal River Unit #3

3. Report Date: 18 May 1977

4. Occurrence Date: 27 April 1977

5. Identification of occurrence:

Regulating rod insertion limits exceeded contrary to Technical Speci-fication 3.1.3.6.

6. Conditions Prior to Occurrence:

Mode 1 power operation. Power reduced to approximately 2108 MWT in ,

order to place Group 7 regulating rods in ful1 insertion during per- 3 formance of Reactor Protective System Functional Test (SP-110). f

7. Description of Occurrence:

At 1950 on 27 Apr111977 during the performance of SP-110, Group 6 regulating control rods moved out exceeding insertion limits by 5%.

The Group was adjusted to within limits by 2002, an elapsed time of U 12 minutes.

8. Designation of Apparent Cause of Occurrence:

Because of previous experience of Group 7 dropping into core (See LER-77-43), power was run back to allow full insertion of that group during performance of SP-110. Subsequent xenon buildup caused Group 6 to withdraw but, because of sequence override, Group 7. remained fully in-serted. Operator failed to observe that rod index limits were exceeded.

9. Analysis of Occurrence:

There were no safety implications with this occurrence.

10. Corrective Action:

Operations personnel have been instructed to monitor the rod index limits more closely,

11. Failure Data:

This was the first occurrence of this type.

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