ML19309D783

AO 50-313/75-03:on 750620,180 Degree Visible Crack Found in Socket Weld on Upstream Side of Isolation Valve RBV-6510F. Caused Not Determined.Valve RBV-6510F Replaced

ML19309D783
Person / Time
Site:	Arkansas Nuclear
Issue date:	07/03/1975
From:	ARKANSAS POWER & LIGHT CO.
To:
Shared Package
ML19309D774	List: ML19309D773 ML19309D783
References
NUDOCS 8004110669
Download: ML19309D783 (3)

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1. Abnormal Occurrenco Report No. 50-313/75-3 1

2. Report Dato: July 3, 1975 3. Occurrence Date: June 20, 1975 4 Facility:

5. Identification of Occurrence:

A visible crack of 180 degrees in socket weld on upstream side of valve RBV-6510F, which is second isolati6n valve to outer seal cavity pressure transmitter on Reactor Coolant Pump "B".

6. Conditions Prior to Occurrence: -

Steady-State Power Reactor Power 0 MWth flot Standby Net Output 0 Mwe Cold Shutdown Percent of Full Power 0 *s Refueling Shutdown Load Changes During Routino Power Operation-Routine Startup Operation ,

Routine Shutdown Operation Other (specify) Hot shutdown s

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7. Description of Occurrence: .

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At approximately 0500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> on June 20, 1975, while at. Hot Shutdown conditions, a leak was discovered on upstream side of RBV-6510F.

Leakage was less than 0.2 gpm and was isolable by valve RBV-6510B.

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goo 4110 b57 March 4, 1975 NSP-10, Rev. 2 Page 2 of 4 -

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O Abnormal Occurrence Report No. 50-313/75-3

8. - Designation of Apparent Cause of Occurrenco:

1 Design , Procedure Manufacture , Unusual Service Condition

Including Environmental 1

Installation / ,

Construction Component Failurc 4

Operator i Other (specify) Not determined at this time. _  ;

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9. Analysis of Occurrence:

There were no safety implications or hazard to the health and safety of plant personnel or the public due to prompt identification and corrective action as well as the small magnitude of the leak.'

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Rtrch 4, 1975 NSP-10, Re v. 2 Page 3 Of 4

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Abnormal Occurrence Report No. 50-313/75-3

10. Corrective Action: 1 l

The old valve was removed and replaced with a new valve.

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11. Failuro Data:  ;

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j No equipment malfunction was involved. The affected 4 eld as identified

] in item 5 is similar to cracked weld ,in Abnormal Occurrence Report No.

50-313/74-12 for which metallurgical examination has been performed.  ;

Results will be available by August 15, 1975.

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4 March 4,-1975 NSP-10, Rev. 2 Page 4 of 4

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