ML20126B696
| ML20126B696 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 12/17/1992 |
| From: | Cross J, Robinson W PORTLAND GENERAL ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20126B698 | List: |
| References | |
| NUDOCS 9212220179 | |
| Download: ML20126B696 (6) | |
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se Portland Generai lI.tectric Company r4 James E. Cross Vice President and Chief Nuclear Officer December 17,1992 Trojan Nuclear Plant Docket 50-344 License NPF-1 U. S. Nuclear Regulatory Commission Attn: Document Contral Desk Washington, DC 20555
Dear Sir:
Status of the Trojan Nuclear Plant Unschedukd Steam Generator inspectiQn The purpose of this letter is to pNvide a discussion of the unscheduled steam generator inspection activities at the Trojan Nuclear Plant. Attachment I to this letter describes the inspection and its objectives, and analyses to be completed. Enclosure I provides copies of Trojan procedures pertaining to steam generator tube rupture, as requested.
Sincerely, e
I bued W. R. Robinson for J. E. Cross Attachment c:
Mr. John B. Martin Regional Administruor, Region V U. S. Nuclear Regulatory Commission Mr. David Stewart-Smith State of Oregon Department of Energy Mr. R. C. Barr NRC Resident Inspector Trojan Nuclear Plant 9212220179 921217 gDR ADOCK 05000344 i
PDR I
121 SW Salmon Street, Portland, OR 97204 l
603/464-8897
SUPPLEMENTAL STEAM GENERATOR DISTRIBUTION Mr. Uoyd Marbet 19142 S.E. Bakers Ferry Road Boring, Oregon 97009 Mr. Jerry Wilson Do it Yourself Committee 570 N.E. 53rd Hillsboro, Oregon 97124 Mr. Eugene Rosolie Northwest Environmental Advocates 302 Haseltine Building 133 S.W. 2nd Avenue Portland, Oregon 97204 Mr. Robert Pollard Union of Concerned Scientists 1616 P Street, Suite 31D Washington, DC 20036 Rev. 7, 12/16/92
Trojan Nuclear Plant Document Control Desk Docket 50-344 December 17,1992 License NPF 1 Page1of3 e
Status of the Trojan Nuclear Plant Unscheduled Steam Generator Inspection Backcround On November 9,1992, a tube leak occurred in the "B" Steam Generator at the Trojan Nuclear Plant (TNP). After investigation, the cause of the steam generator tube leak was attributed to the failure to stress relieve the sleeve installed at the first hot leg tube support plate at Row 25 Column 17 (R25C17).
During the investigation, eddy current testing was performed on the remaining insenice sleeves to confirm that proper stress relief had been accomplished. Eddy current probes having an outside diameter of 0.720 inches are typically used for examination of 7/8-inch steam generator tubes at tube-to-tube support plate (TSP) intersections without sleeves. This testing was perfonned using probe outside diameters ranging from 0.540 to 0.580 inches (small). Probes of this diameter were required, as larger diameter probes would not pass through the tube sleeves. In the process of this inspection, these smaller probes traversed TSP intersections in which sleeves were not installed.
Subsequent to the closing of the steam generators, a decision was made to review the data obtained from the small bobbin coil probes in an attempt to detemiine if significant defects could be identified from the data. This data review focused on those TSP intersections that did not contain sleeves. This review was completed, and although significant questions exist about the reliability of the smaller probe data obtained at intersections not containing sleeves, the values acquired using the smaller probe now will undergo further investigation.
The objectives of this investigation, the inspections to be perfonned, and the analyses to be completed are described below.
Obiectives of this inspection Objective 1: Resolve correlation questions concerning the appropriateness of employing the data obtained from the small bobbin coilin flaw characterization for TSP intersections not containing sleeves.
Objective 2: Confirm defect growth rates are not inconsistent with the safety analysis for the Cycle 14 Interim Repair Criteria.
Trojan Nuclear Plant Document Control Desk Docket 50-344 December 17,1992 License NPF-1
' Attachment i Page 3 of 3 Anoroach to ODSCC/lGA Indications Found during the Examinations If the indications are consistent with the safety analysis for the Cycle 14 Interim Repair Criteria, no repair will be required, but may be performed, based upon economic considerations. Indications will be inspected with the RPC probe if the bobbin coil voltage growth is not consistent with the safety analysis for the Cycle 14 Interim Repair Criteria.
If the RPC examination confirms the indication is Outside Diameter Stress Corrosion Cracking / Inter Granular Attack (ODSCC/ IGA), consideration will be given to performing a reanalysis to ensure suflicient safety margin for the remainder of Cycle 14.
Technical Specification Channe Annlication If the data from examinations and analyses are not inconsistent with the safety analysis for the Cycle 14 Interim Repair Criteria, consideration will be given, based upon economic considerations, to requesting a revicion to the Technical Specifications. The application will request approval to; a) defer the unscheduled inservice inspection until the next refueling outage and, b) allow eddy current bobbin coil indications greater than 1.0 volt to remain in service.
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Trojan Nuclear Plant Document Control Desk Docket 50-344 December 17,1992 License NPF-1 Attachment I Page 2 of 3 Inspections and Analyses to Meet Ohicetives The following inspections and analyses will be conducted for the "C" Steam Generator.
For Obitclim_L Inspections:
Using the 0.720-inch bobbin coil probe, inspect the TSP e
intersections with small bobbin coil voltages indicated greater than or equal to 1.0 volt (approximately 49 tubes). During the examination of these selected intersections, the bobbin coil will transverse some additional intersections. These intersections will also be examined. No inspections using the RPC probe.
Analysis:
Confirm that the intersections measured by the.; mall bobbin coil with voltages indicated greater than or equal to 1.0 volts are not inconsistent with the safety analysis for the Cycle 14 Interim Repair Criteria. Establish if a correlation exists between the small bobbin coil and the 0.720-inch bobbin coil probes.
For Obiective 2:
Inspections:
Using the 0.720-inch bobbin coil probe, inspect the hot leg of the tubes through the seventh support plate that contain the following intersections:
a.
Insenice marginal RPC indications (bobbin coil voltage was less than 1.0 volt in the 1991 inspection; approximately 109 tubes) b.
The 1991 potential indications (bobbin coil indications were not confirmed by RPC in 1991 inspection; approximately 315 tubes)
No inspections using the RPC probe.
Analysis:
Analyze the growth rate data from eddy current data taken at the intersections in the hot legs of the tubes inspected using the techniques described in the PGE Report and safety analysis for the Cycle 14 Interim Repair Criteria as further developed in Appendix A of WCAP 13449, Revision 1.
Trojan Nuclear Plant Document Control Desk Docket 50-344 December 17,1992 License NPF-1 Enclosure I Trojan Procedures Pertaining to Steam Generator Tube Rupture l
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