ML20024D245
| ML20024D245 | |
| Person / Time | |
|---|---|
| Site: | Washington Public Power Supply System |
| Issue date: | 07/21/1983 |
| From: | Delorenzo R WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| To: | Sternberg D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, GO1-83-0366, GO1-83-366, NUDOCS 8308030375 | |
| Download: ML20024D245 (5) | |
Text
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ce ffft Washington Public Power Supply System e,,
P.O. Box 968 3000GeorgeWashingtonWay Richland, Washington 99352 (509)372;5000 C- /:?D,,
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9, July 21, 1983 7.' q;',
G01-83-0366
'4 Nuclear Regulatory Commission Region V 1450 Maria Lane, Suite 210 Walnut Creek, California 94596 Attention:
D.M. Sternberg, Chief Reactor Projects Branch No.1
Subject:
NUCLEAR PROJECTS 1 AND 4 DOCKET NOS. 50-460 AND 50-513 REPORTABLE CONDITION 10CFR50.55(e) SKEWED WELD JOINTS
Reference:
- 1) Telecon, ME Rodin, Supply System to PP Narbut, Region V NRC dated 11/6/81.
- 2) G01-81-414, DW Mazur to BH Faulkenberry, same subject, dated 12/12/81.
- 3) G01-82-0066, DW Mazur to BH Faulkenberry, same subject, dated 3/10/82.
- 4) G01-82-0437, DW Mazur to BH Faulkenberry, same subject, dated 7/16/82.
In reference 1) the Supply System informed your office of a potential reportable deficiency under 10CFR50.55(e) and references 2), 3), and 4) were interim reports on the subject condition.
As a result of further inve stigations which have determi ned that as-installed conditions were inadequate to support the given loads, this deficiency has been determined to be reportable.
In reference 4) the Supply System committed to providing yearly updates on the status of the subject deficiency.
In keeping with that commitment, Attachment A includes a restatement of the condition and narrative on the current status of each of the affected contracts. Per reference 3), it was stated that this deficiency is not applicable to eight of the fourteen contracts.
It is now known that welds on 207A and 253 require rework. The as-built design verification process will identify rework, if required, on contracts 211, 216, 218 and 257. This report provides a final status of the subject deficiency for all contracts except 207A, 211, 216, 218, 253 and 257.
With the construction slowdown at WNP-1 much of the review for these contracts will not be performed until more as-built information is available.
Therefore, yearly updates will be deferred and an update will be provided at restart of construction or more frequently as new information is available.
8308030375 0
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Mr. Sternberg Skewed Weld Joints Page 2 G01-83-0366 If you have any questions or-desire further information, please advise.
D. K @
R. A. De L enzo, Program Manager, WNP-1/4 RAD:LC0:pp
~ Attachment A cc: TA Mangelsdorf, Bechtel (860)
V Mani, United Engineers (897)
NRC Document Control Desk EC Haren, United Engineers (895)
ORM (847)
FDCC' (899) d l
l l
ATTACIMENT A WNP-1/4 DOCKET NOS. 50-460 & 50-513 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 Dl.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 THE 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 responsibility of the contractors 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 For Contracts 207A and 253 it has now been verified that a condition of inadequate effective weld throat exists which could have caused a failure of safety related items.
For Contracts 216 and 218 it has not been verified if a condition of inadequate effective weld throat exists which could have caused a failure of safety related items.
This analysis will be performed during the as-built design verification review.
For Contract 211 and 257, UE&C Engineering has concluded the installed nuclear supports with skewed tee joints are acceptable and there are no safety implications or possible failure of these safety related items.
The non-nuclear SRA supports have not yet been analyzed for consequen-tial failure of a safety related item.
This analysis will be performed during the as-built design verification review.
CORRECTIVE ACTION The affected site contractors (Contracts 211, 257, 216, 207A, 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 suppl ied them by UE&C Engineering.
The contractors have or are implementing the direction provided them by way of the PCPs.
In addition, Bechtel QC has conducted training sessions on the require-ments and inspection for skewed tee joints welds with all the affected contractors QA representatives.
All of the Nuclear Quality Class I skewed tee joints already installed by the 211/257 contractors have been identified. From this list, UE&C Engineering has performed an analytigal review of each joint where the dihedral angle is in excess of 105 to ascertain on a case-by-case basis the acceptability of the joint. Based on calculations performed by UE&C Eggineerjng it has been concluded that for dihedral angles between 90 - 105 there is an insignificant reduction in the effective throat and therefore they need not be considered in the analytical review for any of the contracts.
For Contracts 211/257, UE&C Engineering has taken the original weld size from the detail drawing, and, using the known dihedral angle, computed 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 drawing.
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 has performed their analytical review.
The analysis was made without any compromise of design guidelines or criteria.
The results of this detailed analysis performed for large and small bore i
l nuclear supports established that the supports will meet the design l
loads at the skewed tee joints and would not fail if subjected to the maximum design loads.
Based on the results of the nuclear supports review, the design adequacy of the safety related SRA supports skewed tee connections will be performed during as-built design verification review.
If isolated problems of inadequate weld capacity are identified they will be corrected by PCP direction.
For Contracts 216 and 218, UE&C Engineering has performed a random sample anlaysis of contractor prepared skewed connection supports using the methodology used for Contracts 211/257.
This sample analysis established that the welded skewed connections have acceptable weld capacity.
The allowable range of angles for skewed connections for Contracts 216 and 218 are such that a large reduction in weld capacity does not result and very few, if any, welds are expected to require rework. Therefore, the design adequacy of these skewed tee connections will be verified during as-built design verification review.
If l
isolated problems of inadequate weld capacity are identified, they will l
be corrected by PCP direction.
l 2
e
.s For Contracts 207A and 253, UE&C Engineering has performed a random sample analysis of skewed connections using the methodology applied for Contracts 211/257.
This sample analysis established that the welded skewed connections should have acceptable weld capacity.
For both contracts, QFPCP's have been issued to require identification of all skewed joint configurations that do not conform to the guidelines issued on design, detailing, and inspection of skewed joints.
Contract 207A has reinspected all WNP-1 field skewed connections and UE&C has dispositioned all identified field skewed welds.
Many were dispositioned as rework.
All Contract 207A shop skewed welds will be identified during the current as-built program when a final determination of acceptability will be made. Although no work is currently planned for WNP-4, based on its termination status, any skewed welds would also be identified and verified as acceptable via the final analysis check list process currently included in the as-built program.
Contract 253 has prepared a listing of skewed connections and a description of original weld size measurement technique.
UE&C has evaluated all WNP-1 welds and determined that they are acceptable.
WNP-4 welds have also been evaluated and many require rework.
Although no work is currently planned for WNP-4 based on its termination status, any identified skewed welds would be reworked or verified as acceptable via the final analysis checklist process currently included in the as-built program.
Due to the construction delay of WNP-1 and the indeterminant status of WNP-4, an update status report will be provided upon restart of construction of each unit.
W.
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