ML19329E688

Interim Deficiency Rept Re Underfabricated Pipe Support Fillet Welds.Caused by QC Misinterpretation of Insp Technique.Engineers to Begin More Rigorous Application of QC Insp Instructions

ML19329E688
Person / Time
Site:	Midland
Issue date:	08/04/1978
From:	Howell S CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
References
HOWE-135-78, NUDOCS 8006170820
Download: ML19329E688 (6)

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Consumers l R a, m ( C : .1 p.. ..

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qny-H Power Si+a " "-"

t C0mpany Vice hesident General of fices: 1945 West Parnell Road, Jackson, Michtgen 49201

• Area Code 517 780 0453 s August 4, 1978 Howe-135-78 .

Mr J G Keppler, Regional Director .

Office of Inspection & Enforcement , ,

Region III n; US Nuclear Regulatory Commission .

O 799 Roosevelt Road Glen Ellyn, IL 60137 MIDLAND NUCLEAR PIANT -

UNIT NO.1, DOCKET NO. 50-329 UNIT NO. 2, DOCKET NO. 50-330 PIPE SUPPORT FILLET WELDS

Reference:

S H Howell letters to J G Keppler, Midland Nuclear Plant - Unit 'No 1, Docket No 50-329; Unit No 2, Docket No 50-330; Pipe Support Fillet Welds

1) Serial Howe-197-77, dated November 21, 1977

. 2) Serial Hove-214-77, dated December 22, 1977

3) Serial Howe-ll-78, dated February 10, 1978

4) Serial Howe-36-78, dated March 30, 1978

5) Serial Howe-86-78, dated May 31, 1978

6) Serial Hove-117-78, dated July 7,1978 The referenced letters were interim 50 55(e) reports as is this letter.

The enclosure is Bechtel's final report to MCAR-21 which concludes that a safety problem does not exist with the "underfabricated" field welds.

Consumero Power closed. the CPCo Nonconformance Report No QF-201, dealing with the failure of Bechtel Quality Control to determine discrepancies in field velds, on July 31, 1978. Closure was based on CPCo overinspection of hanger fillet velds concurring with Bechtel inspection results.

A review of the technical reports prepared by ITT Grinnell revealed several errors which require editorial corrections. The errors do not affect the previous conclusion that a salety problem does not exist with the velds'as designed and as fabricated condition. The final 50 55(c) report vill follow obtainin6 the necessary corrections as all other corrective actions have been taken.

8006170 IS O 8 m y7

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2-Howe-135-78 Another report, either interim or final, will be sent on or before September 8, 1978, 4 A **

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Enclosure:

Letter, P A Martinez (Bechtel Power Corporation) to G S Keeley (Consumero Power Company), MCAR-21 Final Report, Revision 1, BLC-6124, dated June 19, 1978*

with MCAR-21 Final Report, Revision 1, dated 6/14/78 as an attachment.

CC: Director, Office of Inspection & Enforcement Att: Mr John G Davis, Acting Director, USNRC (15)

Director, Office of Management Information and Program Control, USNRC (1)

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, Enclosure to

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. Bechtel Power Corporation

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777 East Eisenhower Parkway

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Ann Arbor, Michigan

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u aucess P.O. Doc 1000. Ann Arbor, Michigan 48100

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June 19, 1978

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• BLC-6124

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Consumers Power Company Mr. C. S. Keeley ,

. Project Manager

• 1945 West Parnall Road ,

Jackson, Michigan 49201

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Midland Units 1 and 2

- . Consumers Power Company

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Bechtel Job 7220

_MCAR-21 FINAL REPORT, REVISION 1

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Files,2417/2801

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Dear Mr. Keeley:

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MCAR-21 Revision 1 to the' Final Report covering the field weld size

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discrepancies associated with hanger fabrication is attached for your

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information and use. This Report includes a description of the deficiency, the probabic cause, corrective actions taken to prevent repetition,

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' safety implications with a determination of reportability; conclusions

. and recommendations.

• It has been concluded that the referenced field welds do not compromise plant safety based upon investigative results by ITT Crinnell for welding

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identified in MCARs 18 and 19.

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Very truly yours,

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P. A. Martinez PAM/AEB/pp Project Manager Attachment 2 paEcs. ..

• cc: Mr. R. C. Bauman

• Mr. W. R. Bird Mr. J. L. Coricy ,

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Attcchme t to BLC-6124 ,

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Bechtel Associates Professional Cor poration

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SUBJECT:

HCAR #21 .

Field weld size discrepancies associated with hanger fabrication FINAL REPORT, REVISION 1 f.

DATE: 6/14/78

• PROJECT: Consumers Power Company Midland Plant Units 1 & 2 ,

• Bechtel Job 7220.

• Description of Discrepancy An inspection at the Midland jobsite, using a weld fillet gage, was conducted by Quality Control of a sample of 80 completed hangers consisting

. of 300 field welds. This sample represents 10% of the Q-listed hangers

• with field fillet welds installed to date. The inspection was to deter-mine the actual field weld size compared to Grinnell design and sketches.

It was discovered that, contrary to the specified ficid weld size required by Crinnell drawings, the actual field weld size' for 26 hangers, repre-

.senting 49 field we3ds, were undersize. This deficiency was discovered

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during the investigation of MCARs #18 and #19 which identified similar--

' weld size deficiencies in Grinnell's shop welds. .

• Probable Cause 1.- The field weld sizes shown on the Grinnell drawings do not specify a weld size tolerance. The craft velders produced field welds

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which were undersized compared to drawing requirements.

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2. The principal reason for QC overlooking several undersize fillet

' welds was .apparently a misinterpretation of the QC instructions regarding inspection technique. The instructions require the QCE

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to visually examine to detect the worst condition (e.g. , smalle'st

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veld size), take a measurement to verify acceptance, and visually compare the other items based on this measurement. Instead of the worst case, the,QCE used the most representative case, and by

• applying past practical experience and judgment, ignored what he believed were minor and insignificant variations from the normal.

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Corrective Action

1. The craf t velders and field weld engineers have been instructed that there is no undersize tolerance for field welds,. Welds as deposited must meet the drawing requirements.

2. For all field weld's subsequent to the identification of this defi-ciency, tha QCEs, through further training and monitoring by QC supervision, have instituted a more rigorous application of the QCI instructions. They are no longer modifying the stated inspection technique by applying qualifying judgment and practical experience.

Instead, all undersize welds, no matter what the extent of the undersize condition or for how short a length, are being sought ar.d classified as unacceptable.

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, Attcchment to BLC-6124 , t

' 1I'- Bechtel Associates ProfessionalCorporation HCAR #21 FINAL REPORT, REVISION 1 .

Page 2 .

June 14,1978 ,

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Safety Implications

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Initially, this deficiency was considered a potentially reportabic discrepancy because a safety problem could exist if a Q-listed pipe However, l.

support should fail due to an underfabricated field weld.

based on the results of follow-up analysis which established the design conservatism of the support designs, and the results of the full size destructive loading tests with both underspecified and underfabricated exist.

• welds (reference MCAR #18), we conclude a safety problem does not Field welds identified by this MCAR are similar to the shop welds indentified

• in MCAR #19. Therefore, the Grinnell investigation applies to this MCAR.

Crinnell states that although some of the shop welds are underfabricated there is no safety from the veld sizes specified on the hanger drawings,

- problem because the velds were sized using allowable weld stress 11cvels that were conservative when compared to the Code.

To confirm Grinnell's contention that no safety problem exists, Grinnell

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performed a reanalysis of the 54 discrepant shop welds of the 125 shopThe re

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, welds identified in MCAR #19.

shop welds reanalysized had weld stress levels less than the The maximum complete

' permitted by the ASME Code,Section III, Subsection NF. details of th

" Field Surveyed Welds Stress Analysis for Bechtel Associate Professional Corporation," dated April 19, 1978, which is attached to MCAR #19 Final 9 Report.

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The reanalysis of the discrepant shop relds, the results of the full-

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size destructive loading tests conducted on underspecified and underfabri-cated welds associated with MCAR #18, and the established conservatism of Grinnell's designs, confinn that the safety of the plant This operation deficiency is is

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, not jecpardized by underfabricated shop or field welds.

now considered a nonreportable deficiency.

Conclusions and Recommendations

• The results of the l'TT Grinnell investigations into MCARs #18 and #19 conclude that the identified underspecified and underf abricated welds do not compromise plant safety.

. The discrepant field welds identified by the MCAR are within the tolerance range identified and analyzed by ITT Grinnell for MCARs #18 and #19.

• Based on Grinnell's investigation results attached to MCARs #18 and #19, "

.the welds identified by this MCAR are recommended to be used "as is. I

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' Submitted by: [. D4 f Approved by: %dddduM/

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Concurrence by: Am

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CD/jp 6/15/3

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REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDSLe e DISTRIDUTION FOR INCOMING MATERIAL (30-3'o 330 REC: KEPPLER J G ORG: HOWELL S H DOCDATE: 08/04/78 NRC CONSUMERS PWR DATE RCVD: 08/10/78 DOCTYPE: LETTER NOTARIZED: NO COPIES RECEIVED

SUBJECT:

LTR 1 ENCL /5 FORWARDING DECHTCL"S FINAL REPT TO MCAR -21, CONCLUDING THAT A SAFETY PROBLEM DOES NOT EXIST WITil THE "UNDERFABRtCATED" PIPE SUPPORT FILLET WELDS.

PLANT NAME:M4DLAND - UNIT 1 REVIEWER INITIAL: XJM MIDLAND - UNIT 2 DISTRIBUTER INITIAL:

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