ML19326B388

AO 50-313/74-09:on 741017,leak Found on Cold Leg Drain Loop of Reactor Coolant Pump.Cause Unknown.Socket Weld Filler Matl Applied to Weld & Single Root Pass Made.Leak Test Performed;No Discrepancies Noted

ML19326B388
Person / Time
Site:	Arkansas Nuclear
Issue date:	10/25/1974
From:	Cavanaugh W, Phillips J, Rueter D ARKANSAS POWER & LIGHT CO.
To:
Shared Package
ML19326B382	List: ML19326B381 ML19326B388 ML19326B391
References
NUDOCS 8004150757
Download: ML19326B388 (4)

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1. Abnormal Occurrence Report No. 50-313/74-9

2. Report Date: 10/25/74 3. Occurrence Date: 10/17/74

4. Facility: Arkansas Nuclear One-Unit 1 Russe 11ville, Arkansas

. 5.

Identification of Occurrence: Crack in the socket weld on reactor coolant drain line (CCA-13-1-1-1/2) located between "B" steam generator and "B" reactor coolant pump. The socket weld is located just upstream of Valve RitD-8B a

6. Conditiv.s Prior to Occurrence:

Steady-State Power X Reactor Power ~

1669 Wth Ilot Standby Net. Output 550 We Cold Shutdown Percent of Full. Power 65 %

Refueling Shutdown Routine Startup Operation O

Routine Shutdown '

Operation ,

Load Changes During Routine Power Operation .

Other (Specify) 7 Description of Occurrence: -

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• A one (1) hour leak rate calculation, indicating a 2.15 gpm leakage, was completed at 1245 on October 17,~1974. An immediate investigation com-menced. An entry was made into the reactor building and a leak was four.d in the vicinity of the cold leg drain on loop 8, "B" reactor coolant pump. 3 At that time, it was r.ot possible to identify an exact cause of leakage, whether it was a defective weld, valve bonnet leak, packing, etc. Load reduction and shutdown commenced.

At hot shutdown, a leak was found in the coupling to 1-1/2 inch pipe t. eld of the drain. At that time, the situation was identified as an abnormal '

degradation of the Reactor Coolant Pressure Coundary, s /

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800415073'7 .

July 5, 1974 NSP-10, Rev. O Page 1 of 3

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\~_a' Abnormal Occurrence Report No. 50-313/74-9 Sheet 2

8. Designation of Apparent Cause of Occurrence:

Design Procedure bbnufre.ture Unusual Service Condition Including Installation / Environmental Construction Component Failure Operator __

Other (Sptsify) X Examination of the affected area was conducted by a qualified metal-lurgist, a consultant from Bechtel Engineering. A check of ferrite content of the weld revealed no abnormalities. A dimensional check of the clearance required for the fit up of a socket type weld was dona after the weld was ground out. This check revealed a more than adequate clearance between the coupling and the pipe. The existence of fatigue stress is being considered. Vibration readings were taken

('"'N for further analysis to determine the -possible existence of fatigue stress failure. --

9. Analysis of Occurrence:

There were no safety implications or haz:rd to the health and safety of plant per;onnel or the public, due to prompt identification of the Icak and cooldown to cold shutdown conditions. 2

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10. Corrective Action:

The socket weld filler material on the affected weld was completely ';

ground out. The 1-1/2 inch pipe was reinserted in the socket and a single root pass was made. The surface of the coupling and the single root pass were dye penetrant checked with no indications evident.

Qualified welders, working under a QA program, were used to p<:rform

• this repair. ANO QA/QC inspectors witnessed the entire repair. A leak test was performed with no discrepancies noted. -

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i. July 5, a.t NSP-10, Rev. O Page 2 of 3 -i l

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Abnormal Occurrence Report No.

Sheet 3

11. Failure Mta:

The three other similar welds on drain lines in the reactor coolant system were visually checked _ with no indications noted. A further analysis of the situation is required to determine if the additional investigation is necessary. The results are to be forwarded upon availability.

- j 12 Reviews and Approvals:

Reviewed and Approved by: Plant Safety Committee Yes (X) No ( )

Plant Superintendent

\ ) Yes (X) No ( )

V ._

Reference:

JWA-621 Date: 10/24/74 Reviewed by Date: O f (

Licensing Supervisor 3

Approved by ' # / M -,- ,f .,,[ [ Date: / 8 - Z s '- 7t /

/ a/fet "Re'vla Co 15e '

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Approved by- '

fnager of htfc' lear ServGs Date: /0/ I

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~2 Approved by: h'72,','p/ , ,/mf' Date:

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Director of Power Prod:.tction h"- 1s- 7f Approved by: ]

)- Date: /[ '

M Senior Vice Prdsident ~

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! 4 NM

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July S, 1974 NSP-10, Rev. O Pace t of 7

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