ML19296A864

Interim Deficiency Rept Re Weld Discrepancies in Reactor Vessel Support Structure.All Minor Weld Discrepancies Have Been Removed by Grinding.Other Weld Discrepancies Will Be Mapped for Further Evaluation

ML19296A864
Person / Time
Site:	Beaver Valley
Issue date:	01/04/1980
From:	DUQUESNE LIGHT CO.
To:
Shared Package
ML19296A848	List: ML19296A857 ML19296A864
References
NUDOCS 8002190153
Download: ML19296A864 (2)

Text

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$ BEAVER VALLEY PONER STATION - UNIT NO. 2

}/( INTERIM REPORT ON THE WELD DISCREPANCIES IN

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a REACTOR VESSEL SUPPORT (NEUTRON SHIELD TANK)

SIGNIFICANT DEFICIENCY 79-05 1.0

SUMMARY

A visual inspection of the reactor vessel structural support (neutron shield tank) at the jobsite storage area, by Duquesne Light Company / Site Quality Control (DLC/SQC) personnel, revealed some areas of weld overlap at the toe of two fillet welds, producing a potential lack of fusion condition. A disposition was issued to the jobsite on October 31, 1979, to randomly select approximately 30 percent of the weld overlap condition and to grind the overlap to a depth not to exceed 1/16 in. below base metal surface followed by a magnetic particle (m.p.) inspection. One of the two weld overlap areas revealed no weld indications after grinding and magnetic particle inspection, in accordance with the above disposition.

The second continuous weld area produced a linear indication along one toe of a fillet weld at eleven out of eleven areas randomly selected.

2.0 IMMEDIATE ACTION TAKEN Further grinding was performed on November 29, 1979, beyond the original 1/16 in, below base metal surface, on four of the eleven areas containing linear indications. The results of this grinding effort were evaluated and notification of the potentially reportable deficiency was made to NRC Region I on December 7, 1979, under 10CRF50.55 (3)(1)(iii).

3.0 DESCRIPTION

OF DEFICIENCY In two of the areas the indications were removed by grinding to a depth of 1/4 inch below the base metal surface. The remaining two indications are still present after grinding to a depth of 3/8iinch and 9/16 inch below base metal surface. The linear indications appeared to be confined to the weld metal /

fusion line, along one toe of a 1/2 in. fillet reinforcement of a full penetration weld, joining a 1-1/2 in. thick, cylindrical plate section to a 4 in. thick base flange Based on the limited examination performed to date, the magnetic particle indications appear to be characteristic of a lack of fusion and flux entrapment, resulting from improper welding techniques. The investigation is continuing.

4.0 ANALYSIS OF SAFETY IMPLICATIONS Analysis of safety implications will be provided in the final report.

5.,0 CORRECT VE ACTION TO REMEDY DEFICIENCY All linear indications will be removed and all weld excavations will be rewelded and magnetic particle inspected in accordance with original specification requirements prior to installation.

It is anticipated that complete excavation of the weld discrep-8002190 Zf}h

2 ancy wil,1 commence in mid-January 1980.

All welds on the support have been visually inspected and all minor (cosmetic) weld discrepancies have been removed by grinding. Weld discrepancies, other than those considered to be minor, are being mapped for further evaluation / disposition.

Recurrence of this weld condition will be prevented by removal of all weld surface conditions, such as weld overlap, prior to magnetic particle inspection.

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