ML18024A071

Letter Attaching Bechtel Engineering'S Interim Report on Spot Welding of Struts for SSES Units 1 and 2 and Advising the Commission That the Definitive Report Will Be Submitted by July 31, 1978

ML18024A071
Person / Time
Site:	Susquehanna
Issue date:	04/26/1978
From:	Curtis N Pennsylvania Power & Light Co
To:	Grier B NRC Region 1
References
Download: ML18024A071 (10)

Text

og f> +('OS REGULATORY INFORMATION DISTRIBUTION SYSTEM (RI DS )

DISTRIBUTION FOR INCOMING MATERIAL 50-387/388 REC'RIER B H ORG: CURTIS N W DOCDATE: 04/26/78 NRC PA PWR 5 LIGHT DATE RCVD: 05/Oi/78 DOCTYPE: LETTER . NOTARIZED: NO COPIES RECEIVED

SUBJECT:

LTR 1 ENCL 1 FORWARDING CQNSTRUCTION DEFICIENCY REPT CONCERNING SPOT WELDING OF STRUTS FOR SUBJECT FACILITY> CONTAINING BECHTEL ENGINEERING"S EVALUATION OF THIS REPT.

PLANT NAME:SUSQUEHANNA UNIT i REVIEWER INITIAL: X JM SUSQUEHANNA UNIT 2 DISTR IBUTER INITIAL:

DISTRIBUTION OF THIS MATERIAL IS AS FOLLOWS CONSTRUCTION DEFICIENCY REPORT <iOCFR50. 55<E).

(DISTRIBUTION CODE 8004)

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ve~sesIs~'va eaIa e aawbn+v~ a eels'aTF'r,' vsryysri ~Aa hiero~~ cfear're+i,+pq TWO NORTH NINTH STREET, ALLENTOWN, PA. 18101 PHONE: (215) 821-5151 NORMAN W. CURTIS Vice President-Engineering & Construction 821-5381 April 26, 1978

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NAI g Mr. Boyce H. Grier ~e au 978~

Director, Region I U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, Pennsylvania 19406 gpgp gyp~

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Dear Mr.'Griers relates to a reportable deficiency, under the provisions of 10CFR5855(e),

f/'his WhiCh WaS,identified tO Mr. A. TOth, NRC-RegiOn I, by Mr. A. R. SabOlr PPGLF during a telephone conversation on 3/27/78. The deficiency involves inadequate spot welding of strut material used in field fabricated supports for safety related electrical raceways, HVAC ducts and instrumentation panels. It is concluded that the inadequate fusion, of the spot welding may result in inadequate strength and, as such, represents a deficiency in construction (fabrication) which may adversely affect the safe operation of the plant under design loading conditions.

Bechtel Engineering's evaluation of the information available at present is contained in the attached "Interim Report on Spot Welding of Struts for Susquehanna Steam Electric Station Units 1 and 2ns We anticipate submittal of the required definitive report of the deficiency by 7/31/78.

Very truly yours, 781220084 N. W. Curtis Vice President-Engineering S Construction Attachment CIM:mcb ado tt. ~ Ail PENNSYLVANIA POWER 8, LIGHT COMPANY t(l

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Mr. B. H.-Grier April 26, 1978 cc: Mr. Ernst Volgenau (15)

Director Office of Inspection & Enforcement U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Mr. G. McDonald, Director Office of Management Information and Program Control U.S. Nuclear Regulatory Commission Washington, D.C. 20555

ppg >s 78 08g4 gp INTERIM REPORT ON SPOT WELDING OF STRUTS FOR SUSQUEHANNA STEAM ELECTRIC STATION UNITS 1 AND 2 Prepared by:

Checked Approved b Project Engineer z.Q.3cL .~E, BECHTEL POWER, CORPORATION SAN FRANCISCO, CALIFORNIA April 19, 1978 (P-111b)

INTERIM REPORT ON SPOT WELDING OF STRUTS TABLE OF CONTENTS 1.0 PURPOSE

3.0 DESCRIPTION

OF DEFICIENCY 4.0 ANALYSIS OF SAFETY IMPLICATIONS 5.0 CORRECTIVE ACTION 6.0 REMARKS

INTERIM REPORT APR 19'78 085497 ON SPOT WELDING OF STRUT MEMBERS 1.0 PURPOSE The purpose of this interim report is to provide available information pursuant to 10CFR 50.55(e), concerning the deficiencies observed in spot welding of struts.

2.0 BACKGROUND

'Strut members are light gage channels and are produced by cold rolling mild steel strip. The strut members used on Susquehanna Project are manufactured by Unistrut, Wayne,.

Michigan; Power Strut, Division of Van Huffel Tube Corpor-ation, Warren, Ohio and B-Line, Systems Incorporated, Highland, Indiana. The basic member produced is a channel section. These channel sections are sometimes connected to each other in various configurations such as back to back, back t'o side, or side to side by using a welding process'ommercially known as spot welding or resistance welding. This process essentially consists of passing high current through the thicknesses of adjoining members resulting, in metal to metal fusion.

The channel sections and/or built-up sections are used in field fabricated supports for safety related electrical raceways, HVAC ducts and instrumentation panels, and the governing specification or drawing is 8856-E-53, 8856-M-323-C and JG-16, respectively.

3.0 DESCRIPTION

OF DEFICIENCY Recently there have been a few instances on other nuclear projects where the spot welding was observed to be inad-equate resulting in separation of the adjoining members.

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Therefore, on. March 25 & 26, 1978, an inspection was per-formed on the Unistrut member P1004A and its equivalent by Power Strut and B-Line used in the installed electrical raceway and HVAC duct supports. The method of inspection consisted of 'sounding'he members with a ball peen hammer to detect separated spot welds and verification of the se-paration by insertion of a card between the members at the spot welds. The inspection results indicated a rather high incidence of spot welds with inadequate fusion. Therefore, project Quality Assurance (QA) issued Management Corrective Action Report (MCAR) 1-23 on March 28, 1978.

APR 19 '78 085 Q 97 4-0 ANALYSIS OF SAFETY IMPLICATIONS Various combinations and configurations of channel struts have been used in the support systems. Individual members have been designed as composite sections for which the con-nection (spot welding used in this instance) between adjoin-ing channels is essential to car'ry the postulated loads within established design margins. Thus, inadequate fusion at the spot welding may result in inadequate strength, and may adversely affect the safe operation of the plant under design loading conditions.

5.0 CORRECTIVE ACTION Presently, the deficiency has been observed only for the members with side plates spot welded to the side of a channel (Unistrut P-1004A or its Power Strut or B-Line equivalent). However, it appears that the deficiency may be generic and related to spot welding technique and/or procedure, irrespective of the configuration of the members or the manufacturer. Based upon above, the following action is planned:

5.1 For installed supports.

Spot welded members will be evaluated based on inspection and/or testing of r andomly selected representative samples. Members found to contain deficiencies will be either replaced or repaired. Repair procedures, quired, will be developed later.

if re-5.2 Strut members with side plates which are presently being installed.

On the assumption that spot welding may be totally in-effective, replacement of the equivalent weld capacity is being provided as an interim measure. This will con- .

tinue until the scope of the problem is established, test results are evaluated and final repair procedure, if required, is instituted.

5.3 For the strut members at the jobsite which have not yet been fabricated into supports. I This mater ial will be inspected and tested, and will be repaired or returned to the manufacturer, if required.

APR 19'78 08/49 p 5.4 Corrective action to prevent recurrence.

Surveys of the three manufacturing facilities will be conducted to evaluate current welding techniques and procedures and the adequacy of present quality assurance programs. Based upon the findings of these surveys, we will require the ma'nufacturer to institute corrective actions- to provide adequate assurance regarding the quality of spot welding.

6.0 REMARKS Until sufficient data and information are gathered and a pre-liminary assessment based upon this data is made, a firm" date for submittal of a final report can not be established. How-ever, Bechtel expects that this report will be available in June, 1978.