IR 05000237/1978028
| ML17173A476 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 12/07/1978 |
| From: | Danielson D, Williams C NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML17173A474 | List: |
| References | |
| 50-237-78-29, NUDOCS 7901110049 | |
| Download: ML17173A476 (4) | |
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U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT REGION Ill Report No. 050-237/78-28 Docket No. 50-237 License No. DPR-19 License:
Commonwealth Edison Company P. 0. Box 7 67 Chicago, Illinois 60690 Facility Name:
Dresden Nuclear Power Station, Unit 2 Inspection At:
Dresden Site, Morris, Illinois Inspection Conducted:
October 13, 1978
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Approved By: !_71-LL. ~*v~ ~~-lh-~'--"
D. H. Danielson, Chief Engineering Support Section 2 Inspection Summary Inspection Conducted on October 13, 1978 (Report No. 50-237/78-28)
Areas Inspected:
Examination of Inservice Inspection records for reactor pressure vessel recirculation inlet nozzle safe ends and thermal sleeve attachment weld This inspection involved 3 inspec-tor-hours onsite by 1 NRC inspecto Results:
No items of noncompliance or deviations were identified *
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DETAILS Persons Contacted B. B. Stephenson, Station Superintendent E. E. Potter, OAD Chief R. Janecek, SNED W. Witt, OAD Level, III T. Jansen, Station Engineer Functional Or Program Areas Examined Inservice Inspection Records/Recirculation Inlet Nozzle Safe End-Thermal Sleeve Assemblies On October 6, 1978, NRR had a meeting in Bethesda, Maryland wherein General Electric Company made a presentation to NRC staff and the Pipe Crack Task Force, describing all safe end designs used in BWRs'.
Commonwealth Edison participated in this meeting and provided inspection reports and associated data for the Dresden Unit Z, NZ nozzle safe end examinations as performed during routine inservice examinatio It was believed that these examinations had adequately tested the integrity of the thermal sleeve to safe end weld and adjacent foreign base materia The GE presentation on this basis, stated in summary that the "Dresden Unit Z Plant with least apparent SCC Margin has shown no reportable UT indications in three successive inspection Eight year total service".
Subsequently, (October 13, 1978) the RIII inspector who parti-cipated in this meeting conducted a detailed review of the safe end ultrasonic inspection records at the Dresden Unit Z sit As is documented in RIII "daily report" dated October 16, 1978, this inspection disclosed that ultrasonic examinations capable of detecting defects in and about the safe end thermal sleeve attachment weld was not accomplished during the three most recent ultrasonic examination The licensee's represent-atives concurred with this findin The licensee indicated that ultrasonic test procedures capable of comprehensive 100%
examination of the NZ nozzel safe ends would be developed and implemented no later than the next ISI outage (March, 1978).
This matter is considered unresolved (Z37/78-Z8-0l) and its resolution will be further addressed by NRR and IE *
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- Safe End Ultrasonic Examination Details (1)
Requirements The specified 100% volumetric examination of the N2 nozzle safe ends is not required by Section XI of the ASME Boiler and Pressure Vessel Cod These examina-tions are based on a Commonwealth Edison commitment in response to the substance of NUREG-031 The most recent restatement of this commitment made available to the RIII inspector is documented on Page 3 of Commonwealth Edison/
NRC letter dated January 10, 1978, (Davis/DOR - Edison/
Turbank) where in CE. states (relative to the Dresden Unit 2, furance sensitized safe ends) that "we have inspected in the past and will continue to inspect these safe ends and welds on a greatly accelerated basis."
(2)
Records The records for the three most recent ultrasonic examin-ations of the safe ends do not document any information indicating that the volume of the safe end involving the thermal sleeve to safe end weld was specifically examine The licensee personnel who participated in these examina-tions have concluded that this volume of the safe end (about the thermal sleeve attachment weld) was not examined with procedures capable of detecting cracking eminating from this are The licensee personnel reported that they had contacted the examiners who performed these ultrasonic tests, and they too agree that this area has not been adequately examine (3)
The licensee's representatives stated that the most probable cause for this ommission, is that there is a significant change in the safe end section thickness where the thermal sleeve is attached to the safe en This results in an O.D. configuration which sigificantly complicates the ultransonic examination of the safe end forging where the thermal sleeve is attache In the NRC inspectors estimation approximately 80% of the remainding volume of the safe ends, including the safe end installation welds, have been adequately examined by ultrasoun The licensee's representatives concurned wit with this findin (4)
The Following Documents Were Examined:
Recirculation Inlet nozzle detail "G" drawin Recirculation inlet nozzle machining detail drawing number 113765E-Ol, stampled GE EP No. 201-Safe end ultrasonic calibration record (ISI Unit 2)
dated September 30, 1977, Sheet No. C-2 Record of ultrasonic examination of piping welds, Dresden Unit 2, Weld Number N2C safe end to pipe dated September 30, 197 Record of Nozzle N2-C Liquid Penetran Test of safe end pipe to safe end, safe end to nozzle, dated September 28, 1977, data sheet 07