05000313/LER-1978-009-01, /01T-0:on 780413,B&W Advised Util That Results of 0.04 Ft Squared RCS Pump Discharge Break Analysis Unacceptable.Caused by ECCS Analysis re-evaluation Performed for Newer B&W Plants

/01T-0:on 780413,B&W Advised Util That Results of 0.04 Ft Squared RCS Pump Discharge Break Analysis Unacceptable.Caused by ECCS Analysis re-evaluation Performed for Newer B&W Plants

ML19326B402
Person / Time
Site:	Arkansas Nuclear
Issue date:	04/27/1978
From:	Enos T ARKANSAS POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19326B397	List: 05000313/LER-1978-009, Forwards LER 78-009/01T-0 05000313/LER-1978-009-01, /01T-0:on 780413,B&W Advised Util That Results of 0.04 Ft Squared RCS Pump Discharge Break Analysis Unacceptable.Caused by ECCS Analysis re-evaluation Performed for Newer B&W Plants ML19326B406 ML19326B409 ML19326B416
References
LER-78-009-01T, LER-78-9-1T, NUDOCS 8004150768
Download: ML19326B402 (4)

LER-1978-009, /01T-0:on 780413,B&W Advised Util That Results of 0.04 Ft Squared RCS Pump Discharge Break Analysis Unacceptable.Caused by ECCS Analysis re-evaluation Performed for Newer B&W Plants

Event date:
Report date:
3131978009R01 - NRC Website

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l-Reportable Ocewrey.ce Report No. 50-313/78-9 2.

Report Date:

April 27, 1978 3.

Occurrence Date:

April 13, 1978 4

Facility:

Arkansas Nuclear One-Unit 1 Russellville, Arkansas 72801 S.

Identification of Occurrence:

Results of an analysis of a 0.04 f t2 RCS pump discharge break which had not been previously analyzed and which showed unacceptable results.

6.

Conditions Prior to Occurrence:

Steady-State Power _

Reactor Power 0

MWth Hot Standby Net Output 0

MWe Cold Shutdown y

Percent of Full Power 0

'5 Refueling Shutdown Load Changes During Routine g

Powrer Operation

,j Routine Startup Operation Routine Shutdown Operation Other (specify) 7.

Description of Occurrence:

We were notified on Agril 13, 1978 by our NSSS vendor of the rasults of an analysis of a 0.04 f t-RCO pump discharge break which had not been previously analyzed and which showed unacceptable results.

The unacceptable results occur af ter apprentuately 1700 seconds when one acsumes that one high pressure injection train is working and that 50% of the flow from that EPI pump is not reaching the core due to flow out of the break.

Additional analyses have been perforged by B&W for break sizes of 0.3, 0.2, 0.15, 0.13, 0.1, 0.07, 0.04, ft which show that the worst case break is 0.13 f t2, i n m

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d Reportable Occurrence Report No. 50-?13/78-9 8.

Designation of Apparent Cause of Occurrence:

D sign Procedure Manufacture Unusual Service Condition Including Environmental Installation /

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Construction Component Failure (See Failure Data)

Operator Other (specify)

X Reevaluation of ECCS analysis as a result of analysis results performed for'3&W's newer generation plants. Due to the small probability of this very specific occurrence with concurrent loss of offsite power and failure of a diesel generator there was no significant hacard to the health and safety of the public.

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1 9.

Analysis of Occurrence:

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Without proper cprator action 10CFR50/46 tmits could be exceeded for a limited range of very small break sizes in a specific small L

portion of RCS piping.

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Reportable Occurrence Report No. 50-313/78-9 10.

Corrective Action

Operator action will be taken in the event the Postulated Small

' Break LOCA should occur.

This action will consist of opening the cross connect valve between the two main headers of high pressure injection and opening two isolation valves.

i 11.

Failure Data:

s None i

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