05000302/LER-1979-009-03, /03L-0 on 790124:while Performing Reactor Protection Sys Functional Testing,Rod Group 6 Dropped Into Core,Rod Group Overlap Was Exceeded.Caused by a AC Power Breaker Being Left Open

/03L-0 on 790124:while Performing Reactor Protection Sys Functional Testing,Rod Group 6 Dropped Into Core,Rod Group Overlap Was Exceeded.Caused by a AC Power Breaker Being Left Open

ML19261B499
Person / Time
Site:	Crystal River
Issue date:	02/15/1979
From:	Cooper J FLORIDA POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19261B496	List: 05000302/LER-1979-009, Forwards LER 79-009/03L-0 05000302/LER-1979-009-03, /03L-0 on 790124:while Performing Reactor Protection Sys Functional Testing,Rod Group 6 Dropped Into Core,Rod Group Overlap Was Exceeded.Caused by a AC Power Breaker Being Left Open
References
LER-79-009-03L, LER-79-9-3L, NUDOCS 7902260423
Download: ML19261B499 (2)

LER-1979-009, /03L-0 on 790124:while Performing Reactor Protection Sys Functional Testing,Rod Group 6 Dropped Into Core,Rod Group Overlap Was Exceeded.Caused by a AC Power Breaker Being Left Open

Event date:
Report date:
3021979009R03 - NRC Website

text

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EVENT cEsCairricN ANo Pres AsLE c 1927,whileperformingReactorProtectionSyetemFunctionalTesting(SP-11p) 3i: [At

, rod group 6 dropped into the core.

Group 7 was immediately inserted. Rod

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igroup overlap of 25% - 5 was exceeded contrary to Technical Specification 9

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3.1.3.6. Investigation revealed both AC power breakers to group 6 open.

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, Breakers were restored to their required position and rod withdrawal commenced

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No effect upon health and safety of public as rod group 6 moved in a safe shutdown direction. No previous occurrences.

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ESCRt*T1cN AND CORRECnvE AC90NS h a ! l The cause of this event i c: atteihuted m " A" Ar newo* tmi breker be4~

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,,, inadvertently left open at the completion of a previously performed preventi'ae maintenance procedure PM-126.

As corrective action an additional section to [PM-126 was added to assure system restoration prior to procedural completion.1

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SUPPLEMENTARY INFORMATION Report No.:

50-302/79-009/03L-0 Facility:

Crystal River Unit #3 Report Date:

13 February 1979 Occurrence Date:

24 January 1979 Identification Of Occurrence:

Regulating rod group 6 exceeded overlap contrary to Technical Specification 3.1.3.6.

Conditions Prior to Occurrence:

Mede 1 power operation (100%)

Description of Occurrence:

At 1027, while performing Surveillance Procedure SP-110, Reactor Protective System Functional Testing, rod group six (6) dropped into the core from 97% withdrawn.

Rod group seven (7) was immediately inserted to 0%.

Investigation revealed that both the "A" and "B" AC power train breakers to group 6 were open.

Further investigation determined that the "A" train breaker was inadvertently left open during the performance of Preventative Maintenance Procedure PM-126, Electrical Checks of CRD Power Train. PM-126 was completed just prior to the start of Surveillance Procedure SP-110.

As per the instructions contained in SP-110, the I&C Technician opened the "3"

train breaker being unaware of the open breaker in "A" train. This resulted in the loss of AC power to rod group 6.

The breakers were restored to their required positions and rod withdrawal commenced at 1037.

Designation of Anparent Cause:

The cause of this event is attributed to "A" AC power train breaker being inadvertently left open at the completion of Preventive

}bintenance Procedure PM-126.

Analysis of Occurrence:

Health and safety of the plant and general public was not endangered as rod group 6 moved in a safe shutdown direction.

Corrective Action

An additional section to Preventive Maintenance Procedure PM-126 was added to assure system restoration prior to completion.

Failure Date:

No previous occurrences reported.

/rc