ML20213D511
| ML20213D511 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 01/17/1981 |
| From: | Noonan V Office of Nuclear Reactor Regulation |
| To: | Tedesco R Office of Nuclear Reactor Regulation |
| References | |
| CON-WNP-0326, CON-WNP-326, FOIA-81-223 NUDOCS 8102050223 | |
| Download: ML20213D511 (4) | |
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s JAN 171981 Docket No. 50-397
!!EMORAllDUM FOR:
R. L. Tedesco. Assistant Director for Licensing Division of Licensing FROM:
V. S. Noonan, Assistant Director for Materials and Qualifications Division of Engineering
SUBJECT:
REVIEW OF WNP-2 SACRIFICIAL SHIELD WALL, WELD QUALITY
References:
(a) NRC Memorandum, B. J. Youngblood to F. P. Schauer and S. S. Pawlicki, dated November 20, 1980 Plant Name: Washington Nuclear Project No. 2 (WNP-2)
Suppliers: Burns and Roe Docket No.: 50-397 Responsible Branch: Licensing Branch #1 Responsible Project Manager: ft. D. Lynch Reviewer:
D. E. Smith Description of Task: Evaluation of Applicant's proposal concerning
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known weld defects in WNP-2 sa rificial shield -
wall.
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i Review Status: Applicant's response required Reference (a) requested review of an engineering evaluation for the sacrificial shield wall submitted by UNP-2. This submittal included a rationale for leaving known defects in the weld joints of the sacrificial shield wall.
The Materials Engineering Branch (MTEB) has reviewed this aspect of the submittal, and we conclude the rationale for accepting known defects in the sacrificial shield wall of WNP-2 lacks definition in some areas and is not acceptable in others.
It does not provide enough detailed infonnation to justify all proposed actions.
Our Safety Evaluation is attached.
V. S. Noonan. Assistant Director 3
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WASHINGTON PUBLIC POWER SUPPLY SYSTEM (WPPSS),
NUCLEAR PROJECT N0. 2 SACRIFICIAL SHIELD WALL WELD JOINT QUALITY SAFETY EVALUATION REPORT MATERIALS ENGINEERING BRANCH MATERIALS APPLICATION SECTION The portions of WNP-2's submittal concerning weld defects in the sacrificial shield wall are commented on in the order discussed by the applicant.
I.
INTRODUCTION Although we do not disagree with the " motherhood" and generalizations of this paragraph, it is important to recognize that this structure was built to the American Welding Society's D1.1 which only requires visual inspection of welds for a structurs of this type. The internal or volumetric inspection of the welds was not required during construction. The sizing of welds, the workmanship standards, etc., specified in Dl.1 are based upon providing a structure adeouate for its purpose with visual inspection only. The requirements for qualification of welders and the visual inspection requirements of D1.1 are looked upon as providing a reasonable level of internal cuality of welds. This is an indirect control approach, and has been proven by the extensive number of satisfactory structures built to D1.1 over the years.
,Most of the defects with which we are concerned with in the welds of the sacrificial shield wall of WNP-2 relate to workmanship and sizing of welds. Some welds in this structure have been inspected for volumetric quality, and the defects found and rate of occurrence are about what would be expected for construction to a visual standard, but subsequently inspected for volumetric quality.
We recognize that repair efforts can cause more problems and degrade the structure to a condition worse than its present condition, and that the best solution in some circumstances is to allow the defects to remain without repair.
2 II. DEFECTS NOT BEING REPAIRED A.
Electroslag Weld Indication The electroslag weld indication appears to be acceptable according to the information provided in the report, however no details of the inspections performed are given. Qualification of nondestructive personnel, equipment and procedures should be reviewed by I&E for all welds inspected in this structure.
B.
Incomalete Penetration in Shielded Metal Arc Welds (SMAW)
The volumetric examination revealed indications of the extent and severity that would be expected for normal workmanship in a structure built to a visual standard. We see no reason for further action except verification by I&E as to qualification of nondestructive personnel, equipment and procedures.
C.
IncompletePenetrationinFhuxCoredArcWelds(FCAW)
The high incidence of incomplete fusion of roots in flux cored welds (six of seven inspected) indicates a lack of quality control of welder qualifications. Qualification records of walders who made these welds should be checked by I&E for position and process applicability. The acceptability of these welds depends upon the extent and severity of the defect indications found. Note that on double-bevel T-welds, the indications ascribed to lack of, penetration in the root could actually be lameller tearing. Theextentoftheindication(s) of each weld should determine the action necessary. Further coment will be provided after these specifics are provided by the applicant. Because these indications are located at the root, extensive damage could occur if repair is attempted.
D.
Workmanshio Defects Identified by Visual Inscection The workmanship defects identified by visual inspection are not defined as to extent or severity. Accordingly, it is
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/ recommended that the applicant be required to establish the extent and severity of each defect. Only then can a judgnent be made regarding their acceptability. A justification is needed for leaving each defect as is, instead of repairing to conform to AWS D1.1.
III. Reoair of Structurally Significant Defects We recommend that undersized fillet welds and underfilled butt welds be restored to 01.1 required dimensions. Code requirements are based upon many factors, therefore waiving one aspect of a code without considering all other pertinent factors is poor engineering practice. In this case, the applicable code only requires visual inspection of welds, therefore their internal quality is unknown.
Usually, most welds on stiffened structures are fillet welds where volumetric quality cannot be determined. To give inexperienced welders " arc time" and to evaluate welders with unknown skill levels, they are used to make fillet welds and other unimportant and uninspected welds. The welding codes take this into account in specifying minimum size welds. With the history of poor visual inspection results and the inferred poor quality of uninspectable welds, there is no valid justification presented by the applicant not to require conformance to the code as to fillet weld size or leaving butt welds underfilled.
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