IR 05000282/1979025
| ML19294B386 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 01/22/1980 |
| From: | Danielson D, Ward K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML19294B381 | List: |
| References | |
| 50-282-79-25, NUDOCS 8002280274 | |
| Download: ML19294B386 (6) | |
Text
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U.S. NUCLEAR REGULATORY COMMISSION
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OFFICE OF INSPECTION AhD ENFORCEMENT
REGION III
Report No.
50-282/79-25 Docket No.
50-282 License No. DPR-42 Licensee: Northern States Power Company 414 Nicollet Mall Minneapolis, MN Facility Name:
Prairie Island Nuclear Generating Plant, Unit 1 Inspection At:
Prairie Island Site, Red Wing, MN Inspection Conducted: October 6-10, 1979 and January 3, 1980 Inspector:
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Approved by:
D. H. Danielson, Chief Engineering Support Section 2 Inspection Summary Inspection on October 6-10 and January 3, 1979 (Report No. 50-282/79-25)
Areas Inspected: QA/QC programs, implementing procedures, work activities, and records relative to steam generator tube inspections. This inspection involved a total of 46 onsite inspection hours by one NRC inspector.
Results: No items of noncompliance or deviations were identified.
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DETAILS
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Persons Contacted Northern States Power Company (NSP)
F. Tierney, Plant Manager E. Watzl, Plant Superintendent Engineer and Radiologist Protection S. Gehra, Senior Schedule Engineer
- D. Hansen, Assitant Materials and Special Process Engineer D. Brosche, Materials and Special Process Engineer G. Neils, General Superint.endent, Nuclear Power Plants P. Krompos, Superintendent Materials and Special Process J. Nelson, Maintenance Superintendent G. Lenertz, Associate Production Engineer
- A. Hunstad, Staff Engineer United States Nuclear Regulatory Commission B. D. Liaw, Division of Operating Reactors Weetinghouse Electric Corporation (W)
R. Ingraham, Lead Engineer (Technical Advisor)
E. Westbrook, Field Service Engineer (Coordinator)
Harftord Steam Boiler Engineering and Insurance Company C. Landstrom, Authorized Nuclear Inservice Inspector (ANII)
The inspector also contacted and interviewed other licensee and contractor employees.
- Denotes those present at the final exit interview on January 3, 1980.
Licensee Action on Previous Inspection Findings (Closed) Unresolved Item (282/79-20-01):
IE Bulletin 79-13, Unit I response. The inspector reviewed the response and actions for IE Bulletin 79-13 and have no questions at this time.
(Ref. NRC Report No. 50-282/
79-20; IE Bulletin 79-13 Unit 1 activities)
Functional or Program Areas Inspected 1.
General a.
On October 2, 1979, Prairie Island Unit No. 1 experienced a primary to secondary steam generator tube leak of about 390-2-
gpm. The reactor was brought to a cold shutdown in a routine
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manner following the emergency procedures for such an event.
Fiber opric inspection performed subsequent to the October 2, tube leak revealed that the steam generator
"A",
tube in row 4, column I had a rupture about 3 inches above the tube sheet.
The rupture was a tube burst " fishmouth", about 1 1/2 inches long and with a maximum width of about 1/2 inch. The steam generator tubes in adjacent positions (row 3, column 1 and row 2, column 1) also showed signs of wear. Eddy current examina-ticn revealed that the row 3, column 1 tube (adjacent to the failed tube) had an indication of a 65% reduction in tube thickness. The row 2, column 1 tube (next tube) had an indica-tion of about 20% reduction in wall thickness. All wear marks and the rupture were on the outer peripheral side of the tubes at approximately the same elevation.
A steel coil spring 8.5" long, 1.25" diameter, and 3/32 inch gauge wire was found lying on the tube sheet adjacent to the defective tubes. One end of the spring was wedged between the tube sheet and the flow blocking device (the f]ow blocking device diverts flow away from the open tube lane and into the tube bundle) and the other end was free to move. A visible wear pattern on the tube sheet indicated that the spring had been moving during operation.
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A second spring identical to the first but shorter in length was found on the cold leg side. It was locatti just opposite the first spring with one end wedged under neath the flow blocking device and the other end extending out onto the tube sheet.
In addition, part of a hose clamp was found next to this spring.
A close visual examination of the spring on the cold leg side, the tubes, and the tube sheet surface revealed no sings of spring movement, tube damage, or wear.
The springs and clamp are believed to be part of the hose of the sludge lancing equipment and were apparently left in the steam generator during an outage prior to the installation of the flow blocking device in March, 1976. The springs served functionally to provide radial rigidity to the rubber suction hoses to prevent collapse. The rubber hoses are believed to have disintergrated during service due to the high operating temperature.
A complete visual inspection of the outer peripheral area of the tube bundles and flow lanes for both steam generators revealed no other signs of foreign objects.
In addition, eddy current examination was performed on 12% of the steam generator-3-
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tubes, including all of the row I tubes, all tubes adjacent to
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the damaged tubes, tubes on the periphery of the tube bundle, and a random sample of the tubes in the center of the tube bundle.
In addition to the failed tube, and the tube with a 65% wall reduction, the remaining four tubes adjacent to the failed tube were plugged, b.
Over three of the tubes in SG "B" were ET.
No unacceptable indications were found.
c.
Westinghouse Electric Corporation personnel performed the eddy current examination (ET).
d.
ZETEC was contracted to evaluate W ET.
e.
The ANII was present for the majority of the SG activities.
f.
The next outage for Unit I will be approximately July, 1980, and Unit 2 approximately December, 1980.
2.
Procedures The inspector reviewed the following procedures.
a.
W Eddy Current Examination of Steam Generator Tubing - Pre-service and Inservice, MRS 2.4.2 GED-18, Revision 2, May,1979.
b.
W Steam Generator Tubing Inspection for Tube Wall Degredation Detector and Quantification, MRS 2.4.2 GEN-18, Revision 5, June, 1979.
c.
W Steam Generator Tubing Inspection for Low Level Tube Wall Degradation, Tight Radius B-Bends, MRS 2.4.2 GEN-18, Revision 0, September, 1977.
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W Steam Generator Tubing Inspection for Tube Wall Degradation, d.
Tight Radius U-Bank, MRS 2.4.2 GEN-18, Rev. O, 9/77.
e.
W Installation and Removal of Eddy Current Positioning Devices, MRS 2.4.2 GEN-19, Revision 0, July, 1977.
f.
W, Appendix B, Two Axis Positioner Range and Basetrack Locations for 27, 44, and 51 Series Steam Generators. MR 2.4.2 GEN-19, Revision g.
W Explosive Plugging of Steam Generator Tubes, MRS 2.3.2 GEN-9, Revision 2, September, 1979.
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h.
W Installation and Removal of Temporary Nozzle Covers, MRS
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2.2.2 GEN-2, Revision 3, July, 1979.
i.
W Transportation, Storage, and Disposition of Explosives, MRS 2.3.2 GEN-11, Revision 1, February, 1979.
j.
W Post-Activity Sign-Off for Area Cleanliness, MRS 2.2.2 GEN-6, Revision 2, July, 1979, No items of noncompliance or deviations were identified.
3.
Personnel Certification The inspector reviewed the following NDE personnel in accordance with SNT-TC-1A 1975 Edition.
NAME WESTINGHOUSE LEVEL METHODS W. Monroe ET I
R. Cottrell ET I
E. Westbrook ET IIR (Restricted)
R. Ingraham ET II ZETEC E. McKee ET IIA (Evaluator)
The following W qualified explosive tube weldors were certified to ASME Section XI, 1977 Edition, Winter 1978 Addenda (the only addenda stating qualified explosive welders.) T. Pfart, E. Westbrook, and T. Phillips.
No items of noncompliance or deviations were identified.
4.
Equipment Certification The following items were reviewed.
a.
Calibration blocks b.
Recorders c.
Oscilloscope d.
Vector Anatyze No items of noncompliance or deviations were identified.
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5.
Data Review
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The inspector reviewed the eddy current data on the steam generators and the Licensee Event Report, " Tube Rupture in No. 11 Steam Generator",
dated October 16, 1979 to Mr. J. G. Keppler from Mr. L. O. Mayer.
No items of noncompliance or deviations were identified.
Exit Interview The inspector met with site representatives at the conclusion of the insepetion. The inspector summarized the scope and findings of the inspection noted in the report.
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