ML20041G149
| ML20041G149 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 03/12/1982 |
| From: | Koester G KANSAS GAS & ELECTRIC CO. |
| To: | Seidle W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, KMLNRC-82-174, NUDOCS 8203190330 | |
| Download: ML20041G149 (6) | |
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T*W E LE CTHiC COMPAP4Y GLENN L MOESTER v< r Pas oote r. seuctaan March 12, 1982 fhhfffl\\)
Mr. W.C. Seidle, Chief
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Reactor Projects Branch 2 U.S. Nuclear Regulatory Commission l
j Region IV
!51982 611 Ryan Plaza Drive, Suite 1000
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Re:
Docket No. STN 50-482 Ref: Letter KMLNRC 81-149 dated 12/30/81 fro GLKoester, KG&E, to GLMadsen, NRC IA [ W ] fj { p'f' ~ '
Subj: Final 10CFR50.55(e) Report - Undersize
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Dear Mr. Seidle:
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On September 30, 1980, we reported to the Region.IV off (that 3 undersized socket welds had been found in the Wolf Creek pip 3 97 In the referenced letter we stated that our final report would be submitted on or before March 12, 1982.
Attached is the final report submitted pursuant to Regulation 10CFR50.55(e) regarding the undersized socket welds.
If you have any questions, please contact us.
Yours very truly,
/ed X suel GLK:bb Attach cc: Mr. Thomas Vandel NRC Resident Inspector Attach
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8203190330 820312 DR ADOCK OSOOO dress: PO. Box 208 I Wichsta, Kansas 67201 - Telephone: Area Code (316) 2616451
9 10 CFR 50.55(e) FINAL REPORT On UNDERSIZED SOCKET WELDS.
For WOLF CREEK GENERATING STATION, UNIT NO. 1 KANSAS GAS AND ELECTRIC COMPANY
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March 12, 1982
l of 4 TABLE OF CONTENTS 1.
Introduction 2.
Description of Deficiency 3.
Analysis of Safety Implications 4.
Corrective Actions N '
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n 2 of 4 J
I.
INTRODUCTION Small bore piping size two inches and under is fabricated and erected by the Wolf Creek Constructor (Daniel). Most of the small piping is prefabricated in the on-site weld fabrication shop (shop t
welds) and subsequently moved into the power block and welded into place (field welds). On another project, KG&E's Constuctor had dis-covered that welds inspected and accepted were in fact undersize according to the ASME Code.
Failure to recognize the effect of con-cavity on weld acceptability was the underlying cause of the welds being accepted by that project. The Constructor conducted a study of the i
Wolf Creek welds at that time (January 1980) and determined that such a problem did 'not exist at the Wolf Creek Site. This determination was made using criteria based on checking welds at several positions around the circumference of the weld. However, a reinspection performed on September 26 through September 29, 1980 using a full 360 degree sweep of the weld circumference revealed that a problem with undersized. socket welds on small piping existed. NRC Region IV was notified of the deficiency on. September 30, 1980.
II.
DESCRIPTION OF THE DEFICIENCY For small piping socket welded fittings, the minimum size of the fillet weld between the pipe and fitting body is prescribed by ASME Code rules.
If the fillet weld is concave, the size of the weld is not deter-mined by direct measurement, but by calculation involving a theoretical throat size. This requires a 360 degree sweep of the circumference for weld size determination. Quality Control Procedure QCP-VII-200,
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" Inspection of Welding Process" did _ not clearly state the requirement for a 360 degree sweep. Therefore, u.tdersize socket welds were ac-cepted because the inspections were being made using several positions around the circumference rather than a full 360 degree sweep. This problem did not occur in socket welds made after May 1980.
III.
ANALYSIS OF SAFETY IMPLICATIONS Because of the large number of systems and individual welds involved, analysis to determine the adequacy of undersized welds was not feasible. Further, because socket weld size is a code requirement, the welds must meet the size requirement even if an analysis were to confirm adequate strength to withstand all design loads. The conservative assumption which was made for this situation was to assume that if the welds were to have remained uncorrected, failures would have occurred which would have adversely affected safety.
IV.
CORRECTIVE ACTIONS The following corrective actions were taken to correct the under-size socket welds and preclude similar occurrences in the future:
(1)
The training or retraining for the Daniel Crafts and Quality control Inspectors involved at the time, which > included 19 welders and -3 inspectors, was completed September 30, 1980.
Since that time training and instructions on satisfactory socket joint welding has been an ongoing thing with the training department and is an essential element in the certification of a Level II Welding Inspector.
4 of 4 (2)
The Qualit'y Control Procedure QCP-VII-200
" Inspection of Welding Process" was changed to clearly state requirements (360 check) for inspection of socket welds. Paragraph 4, third sentence of Appendix I, Rev. 6 of QCP-VII-200, Rev. 7 dated 1/21/81 reads as follows:
"The full circumference of socket welds will be inspected, by use of the fillet gauge, or other suitable measuring device, for proper size of weld."
(3)
Inspection was performed on all safety-related Daniel field and shop socket welds made prior to June 1,1980 to determine if weld size (leg length and throat thickness) was acceptable.
(4)
Deficiency Reports were issued for all welds found to be undersize.
L (5)
All welds will be reworked in accordance with the Deficiency Report dispositions.
This will l
result in socket welds which meet all ASME Code l
requiraments.
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