ML19339A581
| ML19339A581 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 10/30/1980 |
| From: | Koester G KANSAS GAS & ELECTRIC CO. |
| To: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, KMLNRC-035, NUDOCS 8011040321 | |
| Download: ML19339A581 (7) | |
Text
'e KANSAS GAS AND ELECTRIC COMPANY T*f ELEC t5*C COMPANv e GLENN L st O E S ? E el w<t**sset=t asunsee October 30, 1980 Mr. Karl V. Seyfrit Director, Region IV Of fice of Inspection and Enforcement U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011 KMLNRC-035 Re:
Docket No. STN 50-482 Subj: Interim 50.55(e. Report regarding Undersized Socket Welds
Dear Mr. Seyfrit:
On September 30, 1980, we reported to your Region IV office that undersized socket welds had been found in Wolf Creek piping.
Attached are two (2) copies of an Interim Report which is submitted pursuant to 10CFR50.55(e).
Please advise f you need additiona. information.
Yours very truly, I
l{d!C A GLK:bb Attach 2 fc: Director, Office of Inspection and Enforcement c/o Distribution Service Branch, DDC, AD*4
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U.S. Nuclear Regulatory Commission
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Washington, D.C.
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Attach 15 Copies TVandel, NRC Site Inspector
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201 N Market - Wochota, Kansas - Mad Address: PO. Box 208 I w1chota. Kansas 67201 - Teoephone-Area Code (;16) 261-6451
O INTERIM REPORT ON UNDERSIZED SOCKET WELDS FOR WOLF CREEK GENERATING STATION UNIT #1 KANSAS GAS AND ELECTRIC COMPANY October 28, 1980
TABLE OF CONTENTS 1.
INTRODUCTION 2.
CHRONOLOGY AND DESCRIPTION OF DEFICIENCY 3.
SCOPE 4.
ANALYSIS OF SAFETY IMPLICATIONS 5.
CORRECTIVE ACTIONS 6.
SCIIEDULE i
9
a.
1.
Introduction This interim report, submitted in accordance with 10CFR50.55 (e),
describes a problem involving the acceptance of deficient socket welds on small piping installed at the Wolf Creek Site under Section III of the ASME Boiler and Pressure vessel Code.
The deficiency was initially reported to the USNRC - Region IV office as a potential 10CFR50.55(e) on September 30, 1980.
Small bore piping size 2" 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 welds) and subsequently moved into the power block and welded into place.
(Field welds) 2.
Chronology and Description of Deficiency For small piping soc,ket welding 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 con-cave, the size of the weld is not determined by direct measurement, but by calculation involving a theoretical throat size.
On another project, KG&E's constructor had discovered that welds 4
inspected and accepted were in fact undersize according to the Code.
Failure to recognize the effect of concavity on weld acceptability was the underlying cause of the welds being accept-ed by that project.
The Constructor conducted a study of Wolf Creek welds at that time (January 1980) and determined that such a problem did'not exist at the Wolf Creek Site.
This
-1.-
'dstcrmination w c mads using critoria based on checking wolds at several. positions around the circumference of the weld.
Since'that time, however, a re-examination of socket welds using a full 3600 sweep of weld circumference (as opposed to several position checks around the circumference) has revealed that 'a problem with undersized socket welds on small piping does exist.
The're-inspection was performed on 9/26/80 through 9/29/80 and NRC Region IV was notified of a potential 10CFR50.55(e) nonconformance on 9/30/80.
Daniel Corrective Action Report
- 1-M-007 was issued at that time.
3.
Scope Inspection of shop and field welds completed to date shows that:
1)
Weld rejection rate is 7 to 10%
2)
Installation or field weld problems were limited to 2" heavy wall pipe (1h ",1", 3/4 " and 3/8" pipe was i
determined to be acceptable) 3)
Problems with welds made in the fabrication shop were isolated to a time period prior to May, 1980 4)
Installation or field welds could not be isolated to a particular time period.
4.
Analysis of Safety Implications The design and acceptance criteria for the socket weld size is a code rule, therefore failure to comply with a minimum size is considered reportable under 10CFR50.55 (e).
Because of.the large number of systems and individual welds involved, analysis to determine the adequacy of individual undersized r '
welds is'not considered to be productive, therefore all deficient welds identified will be repaired by procedure.
5.
Corrective Actions Actions to correct the problem and prevent recurrence consist of the following:
1)
Daniel Corrective Action Report was issued on 9/30/80 2)
All field installation socket welds have been or will be reinspected and'those found deficient will be repaired 3)
All socket welds made prior to May, 1980 have been or will be reinspected.
Those found deficient will be repaired 4)
Socket welds made after April 30, 1980 will be sample reinspected to confirm that the problem does not extend,t$ welds made during this time period 5)
Travelers involving small piping have been placed on hold at Traveler Stations 6)
Deficiency Reports are being generated for all welds identified as deficient 7)
All future inspection of welds will include 3600 criteria including the entire weld circumference 8)
A retraining program has been completed for all Fabrication Shop and Quality Control personnel 9)
A retr'aining program for field personnel is currently being established 10)
The Quality Control Department has re-emphasized socket weld inspection procedures and the inspection process.
6 '. - Schedulo Due to the nature of this problem,,it will take several months to identify all nonconforming welds and complete corrective actions.
We expect to have all actions'com-pleted by. July 1, 1981 and at that time will submit a final report or a status report if all corrections are not completed.
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