ML20086D100

Preliminary Deficiency Rept Re NSSS Primary Loop Pipe Welding.Discrepant Conditions Discovered on 730920.Welding Halted Until Faulty Conditions Corrected.Wismer & Becker & Westinghouse Conducting Investigations

ML20086D100
Person / Time
Site:	Diablo Canyon
Issue date:	10/24/1973
From:	Searls F PACIFIC GAS & ELECTRIC CO.
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML20086D064	List: ML20086D075 ML20086D098 ML20086D100
References
NUDOCS 8311300155
Download: ML20086D100 (4)

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. Mr. R. H. Engelken, Director ..

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Directorate of Regulatory Operations .

Ragion V U. S. Atomic Energy. Commission

• P. O. Box 1515 .

Barkeley, California 94701 Re: Docket No. 50-275 Diablo Canyon Unit 1

Dear Mr. Engelken:

On Friday, September 21, 1973, the Region V office was notified by our Director of Quality Assurance of apparent discrepan-

cies between the manner in which work was performed on the Diablo Canyon Unit 1 nuclear steam supply system primary loop piping and

,; the manner in which this work was supposed to be performed under the cpecification. The apparently discrepant conditions were discovered '

Thursday, September 20, 1973, by one of our Construction Department field engineers during a routine inspection of work in progress followed by a review of the performing contractor's (Wismer & Becker) documentation. The affected work was stopped the day of discovery by the field engineer. Pending satisfactory resolution of the

-cpparent. discrepancies, no further welding or other work or activities cn-the pipe and equipment which could be detrimental to the investiga-tion and resolution of the apparent discrepancies will be permitted.

Work will resume when a course of action to correct faulty conditions, if any exist,~is determined, or when we are satisfied that the work as it presently exists, although not performed in strict accordance with procedure and specification, has been properly documented and does not

- compromise quality requirements.

Discrepant Condition #1: Paragraph 6.7 of Specification 8752

( .provides in part as follows: ,

Weld defects revealed by non-destructive examina-tions shall be eliminated and repaired in accord-ance with a procedure approved P- oristructor.

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H. Engelken . October 24, 1973 Atomic Energy Commission Page 2 ,

In disregard of this requirement,.the contractor, following radio-graphic examination of welds No. 2-5A and.3-2A, performed work to

.- ' remove discontinuities without appropriate documentation.

The contractor's explanation is that the specific radio-graphic examinations were not called for by the specification, procedure or code, but were made as a decision on their part to check the quality of their workmanship with welding of each joint cpproximately one-half completed. From the radiographs, they determined the apparent discontinuities were within acceptance limits of the code but, exercising conservative . judgment, decided to take corrective removal action to eliminate the possibility of later interpretation of the discontinuities as rejectable at final inspection ~. The contractor has agreed'that repairs of this type chould have been, and will henceforth be, treated in strict and complete accordance with established procedures with documentation.

PGandE Minor Variation No. M228 and Wismer & Becker Non-Conformance Report No. 13 have been initiated to document this discrepancy.

Discrepant Condition #2: Paragraph 6.68 of Specification 8752 provides in part as follows:

Cutting of stainless steel materials shall be -

performed by machining, sawing, or iron-free aluminum oxide abrasive discs'.

Paragraph 3.67 provides in part as'follows: '

, Grinding and polishing shall be done using only

' . rubber or resin bonded aluminum oxide or silicon

, carbide grinding wheels.

Wismer & Becker's Weld Repair Procedure #3500-200 requires that:

Material removed shall.be by grinding with rubber ,

1 or resin bonded aluminum oxide or silicon carbide.

, grinding wheels which have not previously been j used on other. types of material.

Contrary to these requirements, the contractor used the l carbon-arc gouging process in removing weld material from Weld No. 3-2A.

l As a result PGandE has revised paragraph 6.68 to read as follows:

Cutting of stainless steel materials shall be -

performed by machining,-sawing, or iron-free l

aluminum oxide abrasive discs. Where approved by Constructor, carbon air arc gouging may be i

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used for removing weld metal providing that the ex'cavation is prepared for repairs by removing

? . all remaining slag, scale or oxides, by machining or grinding 1/16' inch minimum to sound metal.

Sound metal shall be veri'fied by liquid penetrant examination. Grinding shall be with rubber or F -

resin bonded aluminum oxide or silicon carbide

, grinding wheels not previously used on other E

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materials . .

Wismer & Becker's Weld Repair Procedure No. 3500-200 has been

' revised to include this specification change, and. the revision is in the process of review and approval. Repairs to Weld No. 3-2A will be made according to the revised procedure when it is approved.

PGandE

'- . Deviation No. 181 and Wismer & Becker Non-Conformance Report No. 11 are being processed to document this discrepancy.

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i . Discrepant Condition #3i Paragraph 6.54 of Specification 8752 provides as follows:

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, Wold metal layers generally shall not exceed 1/8

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f inch in thickness in order that a minimum amount i of base metal penetration will result. All welds E

shall be deposited as stringer beads. Welds shall E be made by making a complete pass over the joint P before going to.the next pass. " Block" welding b technique shall not be used. Weaving shall not y exceed two'clectrode diameters or the gas cup r orifice inside diameter. The manner of depositing g weld metal shall be such that cutting of a, groove

. face shall be held to a minimum.

Wismer & Becker's Weld Procedure No. 3500-1 reiterates these require-L ments. In our judgment Wismer & Becker used alignment-welding tech-E niques to maintain apparatus and pipe alignment'during welding of the b

primary c.ystem which were in violation of the PGandE atT Wismer & Becker s

procedures. In addition, .their method of welding, utilizing the some-time simultaneous services of two welders in diagonally opposed k

quadrants, did not rigidly conform to specification and procedure.

PGandE, with assistance from Wismer & Becker'and Westinghouse

Electric Corporation, has embarked on a comprehensive investigative

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program to evaluate the quality of the welds, both completed and partially completed, of the primary coolant loop main piping. The h condition of the welds,~ pipe and equipment is being carefully reviewed with analytical and physical investigation, as deemed appropriat'e, to

{ determine the consequences of the discrepant actions.

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, Engelken 9 9 October 24, 1973

omic Energy Commission ,

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In order to determine the quality of weld joints Nos. 3-5A '

.nd 3-5B a non-destructive examination program recommended by -

Westinghouse was undertaken commencing October 10, 1973. This pro-gram included visual examination with magnification, a dye penetrant examination, and 300 KV X-ray examination of carefully prepared _- -

surfaces of the welds. The findings of this examination are being evaluated by Westinghouse, and the conclusions will be submitted to D PGandE.

PGandE's Department of Engineering Research, assisted by the General Construction Department, is conducting a thorough review of the thermal history of both completed and partially completed field welds on the primary coolant loop, and the results of their report will be considered, together with the Westinghouse findings, by PGandE's Engineering Department. It is presently expected that complete findings with conclusions will be available in November.

If further investigative steps are determined to be necessary, they will be defined and initiated at that time. PGandE Deviation No. 182 and.Wismer & Becker Non-Conformance Report No. 12 are being processed to document this discrepancy. A final report of the resolution of this discrepancy will be submitted to you. .

Preliminary results indicate that the work performed to date is in accordance with the intent of Specification 8752, the nuclear steam supplier's recommended installation procedures, and the ASME Boiler and Pressure Vessel Code requirements. To prevent future discrepancies PGandE currently is reviewing the Specification, the EllREF contractor's work proce.dures, and the nuclear steam supplier's .jyp~

tecommended installation procedures to provide improved guidelines M l. ;

where necessary and to remove ambiguities and deficiencies if they are wen found to exist. W. ?

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Both PGandE and Wismer & Becker are concerned with the &T disclosure of these apparent discrepancies. Effective October 1, N[

a welding supervisor was assigned by Wismer & Becker, full-time, to1973,(ff.

oversee welding operations, to coordinate the activities and training ff .y of foremen and welders, and to assure that procedures are rigidly 7f./ (.

followed. PGandE, on Octobe/ 10, 1973, instituted a special training program for on-site field engineering and inspecting personnel to [PC. J. ".

refamiliarize them with the quality requirements of on-site activities. M ..

This program will continue until we are satisfied that our people are -41 (

fully informed and that all work is in full compliance with applicable 4 :.

quality requirements. .

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Wry truly yours, ,p. L,.,,.

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Dr. Donald F. Knuth, Director Directorate of Regulatory Operations U. S. Atomic Energy Commission Office of Regulation Washington, D. C. 20545 Re: Docket 50-275 ..

Dear Dr. Knuth:

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Enclosed is a copy of a letter we addressed to Mr. R. H. Engelken which, under 10 CFR 50.55, should have ..

been addressed to you. If you require a copy actually addressed to you, please let ne know. The final report will, of course, be so addressed.

Very truly yours, i

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Dear Dr. Knuth:

Enclosed is a copy of a letter we addressed to Mr. R. H. Engelken which, under 10 CFR 50.55, should have been addressed to you. If you require a copy actually addressed to you, please let me know. The final report will, of course, be so addressed.

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