ML20042A634
| ML20042A634 | |
| Person / Time | |
|---|---|
| Site: | Washington Public Power Supply System |
| Issue date: | 03/10/1982 |
| From: | Mazur D WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| To: | Faulkenberry B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, GO1-82-0066, GO1-82-66, NUDOCS 8203230631 | |
| Download: ML20042A634 (4) | |
Text
Docket Nos. 50 l+60/513 jfff i
50 55(e) Report Washington Public Pcwer Supply System P.O. Box 968 3000 George Washington Way Richland. Washington 99352 (509)372-5000 e
- March 10, 1982 8 \
G01-82-0066 DECE4VED $"
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Region V e a 1450 Maria Lane, Suite 210 4 9 d Walnut Creek, California 94596 6 Attention: Mr. B.H. Faulkenberry Chief, Reactor Construction Projects Branch
Subject:
Nuclear Projects 1 and 4 Docket Nos. 50-460 and 50-513 Potentially Reportable Condition 10CFR50.55(e) Skewed Weld Joints
Reference:
(1) Telecon M.E. Rodin, Supply System to P.P. Narbut, Region V Nuclear Regulatory Conmission dated November 6,1981.
(2) G01-81-414, D.W. Mazur to R.H. Faulkenberry, dated December 12, 1981.
In reference (1) the Supply System informed your office of a poten-tially reportable deficiency under 10CFR50.55(e) and reference (2) was an interim report on the subject condition.
In reference (2) the Supply System committed to providing quarte'ly updates on the status of the subject deficiency. In keeping with that connitment, Attachment A includes a restatement of the condition and a narrative on the current status of each of the affected contracts. A final determination as to the reportability of the subject condition 4 has yet to be made because of the limited amount of information cur-rently available. Therefore, we will continue to provide your office with interim reports on a quartery basis.
DO o!$0$$[o PDR hi t e2 x
Mr. B.H. Faulkenberry Page 2 If you have any questions or desire further information, please. advise.
Very truly yours, 7
D.W. Mazur Program Director CRE:MER:mb Attachment cc: C.R. Bryant, Bonneville Power Administration /399 V. Stello, Director of Inspection, NRC A. Toth, Resident NRC Inspector /819 FDCC/899 EW Edwards, Bechtel/860 V Mani, UE&C/897 i
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ATTACINENT A WNP-1/4 DOCKET NOS. 50-460 AND 50-513 POTENTI AL REPORTABLE CONDITION 10CFR50.55(e)
SKEWED TEE JOINT WELD SIZE INTERIM REPORT _
BACKGROUND Apparent undersize fillet welds on skewed tee joints with obtuse angles were identified during a routine inspection by the WNP-1/4 resident NRC inspector, Mr. A. Toth. This created a question of whether or not the design criteria for increased weld size to obtain the required effective throat for skewed tee joints was properly implemented. In accordance with AWS D1.1 skewed tee joints are defined as having a dihedral angle of not less than 60 degrees nor more than 135 degrees.
The design criteria for the weld size of a skewed tee joint is based on an equivalent sized 90 degree tee joint fillet size. The fillet weld leg length is increased to provide an effective throat for obtuse angle tee joints which is equivalent to a 90 degree tee joint weld. Fillet welds on acute angle tee joints inherently results in an increased weld leg length which provides an effective throat greater than an equivalent sized 90 degree tee joint weld.
DESCRIPTION OF POTENTI AL DEFICIENCY All obtuse skewed fillet welds detailed by UE&C on the drawings used by the contractors have been sized based on a 90 degree tee joint fillet.
UE&C considered it the reponsibility of the conractors to recognize the need for increased leg lengths on obtuse angle skewed tee joints for angles up to 135 degrees. However, it appears the contractors assumed that the weld size specified on the detail drawings provided by UE&C were correctly sized and no adjustment in leg length was necessary for the skewed tee joints. With weld sizes applied as detailed, a condition of inadequate effective weld throat could result for obtuse angle tee joints.
Sample analysis performed by UE&C has indicated that an inadequate effective throat could result if the weld size was not increased for the skewed tee joint fillet welds. In any event, not following the criteria for skewed joints would result in undersized welds. Whether or not an inadequate effective throat exists depends upon the applied loads and the degree of conservatism in the design.
SAFETY IMPLICATIONS It has not yet been verified if a condition of inadequate effective weld throat exists which could have caused a failure of safety related items.
IMMEDIATE CORRECTI'E ACTION The affected site contractors (contracts 211, 257, 207A, 216, 218, and 253) have been issued PCPs specifically directing them to increase the weld sizes (leg length) for skewed welds shown on the detail drawings supplied them by UE&C Engineering. The contractors are implementing the direction provided them by way of the PCPs. In addition, Bechtel QC has conducted training sessions on the requirements and inspection for :;kewed tee joint welds with all the affected contractors QC representatives.
All of the Class I skewed tee joints already installed by the 211/257 contrac-tors have been identified. From this list, UE&C Engineering is performing an analytical review of each joint where the dihedral angle is in excess of 1050 to ascertain on a case by case basis the acceptability of the joint.
Based on calculations performed by UE&C Engineering it has been concluded that for dihedral angles between 900 - 1050 there is an insignificant reduction in the effective throat and therefore they need not be considered in the ana-lytical review for any of the contracts.
For contracts 211 and 257, UE&C Engineering is taking the original weld size from the detail drawing, and, using the known dihedral angle, computing what the reduction in the theoretical throat would be. This calculation is based on the assumption that the welded joints were installed per the detail draw-ing. Currently there is nothing to indicate that the joints were not installed in accordance with the detail drawings. Utilizing this reduced throat size and the load data, UE&C Engineering will perform their analytical review. This review should be completed by June 1982. For those instances where the analysis indicates that the weld would not support the design load, 4 a PCP will be issued to affect repair / rework. A status log will be maintained to track which action was required. This inspection / repair / rework program will be administered by Bechtel QC. It is anticipated that this program will be completed by July 1982.
For contracts 216 and 218, a sample analysis of skewed connections has not yet been performed by UE&C. The analysis and the results should be available by the time the next interim report is due.
Far contracts 207A and 253 all skewed connections have been reinspected.
Welds which were found to be undersized are being reported by the contractors via inspection reports to UE&C Engineering. UE&C is evaluating these weld sizes for design adequacy, Those found not to be adequate will be repaired /
rework ed. A review of the shop welds for contract 207 revealed that fillet welded skewed joints were not utilized in the shop fabrication process; instead of welded skewed connections bent plates or partial penetration groove welds were used.
For contracts 217 and 262 no safety related skewed joints have been installed. The contractors have received and are implementing PCP's which clarify the requirements for welding skewed connections.
As a point of clarification contracts 204, 213, 243, 246 and 254 were reviewed by UE&C engineering to ascertain whether or not these contractors are or would have been required to make fillet welded skewed joints. It was determined by Engineering that none of these contract require (d) the use of skewed welds.
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