ML19262C600
| ML19262C600 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek, Callaway  |
| Issue date: | 11/28/1979 |
| From: | BECHTEL GROUP, INC. |
| To: | |
| Shared Package | |
| ML19262C598 | List: |
| References | |
| NUDOCS 8002140642 | |
| Download: ML19262C600 (5) | |
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FINAL REPORT ON Gulf & Western Preassembled Formations For Callaway Plant Unit No.1 (Union Electric)
And Wolf Creek (Kansas Gas and Electric)
Bechtel Power Corporation Gaithersburg November 28, 1979 800214g hy2
TABLE OF CONTENTS 1.0 Introduction 2.0 Description of Deficiency 3.0 Chronology of Events 4.0 Analysis of Safety Implications 5.0 Corrective Action 6.0 Conclusion
1.0 INTRODUCTION
In co=pliance with 10CFR50.55(e), this report is being issued due to rejectable indications found in velds in preasse= bled piping for=ations manufactured by Gulf & Western (G&W), Paola, Kansas.
The scope of this report includes preasse= bled for=ations fabricated, delivered, and ir so=e cases, installed at Ucion Electric's Callaway Unit One and Kansas Gas & Electric's Wolf Creek Jobsite.
2.0 DESCRIPTION
OF DEFICIENCY This reportable deficiency to the NRC is based on an investigation of three piping for=ations (For=ation Nu=bers A- % 151, A-47-135, and A-52-135) at the Callaway Jobsite.
During this investigation the velds for these for=ations were foand to include i=co=plete penetration, inco=plete fusion, and slag inclusions.
Radiographs for 22 of 52 welds reviewed on these formations by Bechtel indicate rejectable defects.
Additionally, the radiographs for 31 velds were found to be unacceptable due to i= proper radiographic technique. These 31 velds were reshot and the nu=ber of welds rejected for radiographic technique proble=s was reduced to 16.
Si=1lar veld quality and radiographic technique defects have been indicated in other for=ations previously delivered to Wolf Creek and Callaway Jobsites.
3.0 CHRONOLOGY OF EVENTS In March, 1979, visual a n -inations of preassembly For=ation A-9-111 at Wolf Creek Site indicated concerns regarding weld quality and radiographic techniques employed by G&W.
These initial concerns were' followed up in April and May with detailed inspections and audit of preasse=bly for=ations delivered to both SNUPPS jobsites.
These audits and inspections indicated substantial nonce =pliances to specification and ASME Code require =ents.
These nonco=pliances involved radiographic technique; (i.e., i= proper fi1= density, =ultiple penetra=eter i= ages, incorrect penetra=eter place =ents and surface indications inhibiting radiographic interpretation) as well as visible weld discrepancies involving inco=plete fusion, surface porosity and i= proper veld profiles. A hold was subsequently placed on installation of safety-related preassembly for=ations fur =ished by C&W.
Between May 17, 1979 and June 28, 1979, a series of =eetings took place between Bechtel, SNUPPS, KG&E, UE, and G&W to (1) deter =ine the extent of the weld quality and radiographic technique proble=s and (2) develop a course of re=edial and corrective actions.
These actions included a 100 percent av=-4 nation by G&W of all weld radiographs; this av=*4 nation co=pleted in early June indicated deficiencies in radiographic technique of between 35 and 50 percent.
Further discussions with G&W =anage=ent resulted in project agree =ent to surface grind and reradiograph, using corrected RT techniques 5 all preasse=bly for=ation welds subj ect to RT av=-4n= tion ; other safety-related for=ations not requiring radiographic av="4 nation; i.e., Class III asse=blies
Page 2 would also be included in this rework agreement.
Selected formations not yet installed were returned to G6W in June for rework under strengthened project surveillance.
Formations re=aining at the jobsites would be reworked by G&W in the field under site inspection and surveillance.
Criteria, procedures, and inspection arrange =ents governing the rework effort were established over the next several months and actual on-site work initiated at Callaway Site in early October.
NRC I/E representatives for the two SNUPPS sites were informed of the preceding investigation and rewsrk plans.
The NRC representatives were informed that a determination regarding report-ability of these deficiencies under 10CFR50.55(e) regulation would be made upon identification of significant veld defects.
On-site rework; i.e., visual inspection, surface grinding and reradio-graphy of the first three assemblies at Callaway Site were completed in early Nove=ber. After completion and acceptance of the rework effort by G&W and the G&W Authorized Nuclear Inspector, Bechtel, and Daniel /
Union Electric inspection indicated the presence of rejectable veld defects as well as continuing radiographic technique difficulties.
The nature of these defects suggest the potential for adverse safety consequences; as a result, these findings were reported on Nove=ber 2 to the NRC by Union Electric persuant to 10CFR50.55(e) regulations.
Subsequently, G&W has been directed to discontinue all efforts with the exception of five units on the SNUPPS preasse=blies 1.ocated at their Paola, Kansas facility which are in the final stages of completion.
4.0 ANALYSIS OF SAFETY IMPLICATIONS G&W has fabricated 32 safety-related piping formations for each of the two SNUPPS Sites (Callaway and Wolf Creek).
These 32 preasse=blies are part of the following safety-related systems:
A.
B.
Chemical and Volume Control (BG)
C.
Component Cooling Water (EG)
D.
Eigh Pressure Coolant Injection (EM)
Each system relies upon at least one of these preasse=blies to effect a safe shutdown of the plant concurrent with either a safe shutdown
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earthquake or a design basis accident.
Failure of the welds in certain of these preassemblies could significantly degrade the functionability of critical systems to the extent that safe shutdown capability is compromised.
Due to the potential safety implications for safe shutdown, the generic welding problems identified in this report are dee=ed to constitute a significant reportable deficiency pursuant to 10CFR50.55(e).
l Page 3 5.0 CORPICTIVE ACTION The cause of the problem was inadequate control by G&W of welding and
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NDE operations.
Due to G6W's inability to perfom satisfactorily, the responsibility for rework and reinspection (including NDE) and repairs (where required) of the for=ations has been transferred to the Constructor (Daniel International Corporation) at both jobsites.
The rework will be perfomed in accordance with the Constructor's Quality Assurance Programs and applicable Codes.
Five preasse=blies - four for Callaway (including three preassembled for=ations previously returned for rework) and one for Wolf Creek, which are at G&W's facility at Paola, Itansas and which require e4n4-=1 effort to ce=plete, will be finished by G&W.
This work will be perfor=ed by G&W under increased surveillance by Bechtel and will be receipt inspected at each of the SNUPPS jobsites.
6.0 CONCLUSION
All safety-related preassembly for=ations for both SNUPPS Sites will be reworked. Rejectable indications in the welds of preassembled for=ations will be satisfactorily corrected by the Site Constructors.
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