ML18054B353
| ML18054B353 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 01/04/1990 |
| From: | Berry K CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-69344, NUDOCS 9001110103 | |
| Download: ML18054B353 (3) | |
Text
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consumers Power POWER I Nii MICHlliAN'S PROliRESS General Offices:
1945 West Parnall Road, Jackson, Ml 49201 *,(517) 788-1636 January 4, 1990 Nuclear Regulatory Commission Document Control Desk Washingto~,~DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT -
STEAM GENERATOR TUBE INSPECTION CONTINGENCY PLAN (TAC NO 69344)
Kenneth W Berry Director Nuclear Licensing By letter dated December 12, 1989, Consumers Power Company committed to provide the NRC with our inspection plans in the event of a steam generator tube leak outage.
In addition, Consumers Power Company is providing justification to support an exemption from the tube wastage inspections required by Palisades Technical Specificat~ons.
Within the referenced December 12 lette~, Consumers Power Company provided administrative operating criteria for primary to secondary leakage limits.
These administrative limits are more conservative than the existing Technical Specifications.
Between startup from the Fall 1989 maintenance outage and replacement of the Palisades Steam Generators, in the event of a tube leak outage, Consumers Power Company intends to implement the following inspection plan once the leaking tube(s) is identified:
- 1.
Inspection o.f tubes within two rings of tubes around the leaker.
Inspect all tubes within two rings of tubes around crack-like indications.
Continue inspections until all tubes containing crack-like indications are bounded by two rings of clean (ie., serviceable) tubes.
- 2.
Evaluate the location of the leaker.
Determine if the tube is located in a high stress area.
High stress areas consist of thei following:
Areas identified by MPR Associates in.their support plate stress evaluation report (MPR-1125, Palisades Steam Generator Proposed Eddy Current Inspection Plan, May 1989).
These regions are applicable to both the hot and cold legs.
Areas subject to large thermal expansion loads such as tubes adjacent to areas of plugged tubes or to lugs.
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PDC OC1289-0013-NL02 A CMS' E'/VERGY COMPANY
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Nuclear Regulatory Commission Palisades Nuclear Plant S/G Tube Inspection January 4, 1990
- 3.
Expand the inspection based on the tube's location.
If the tube is located in a high stress area the following tubes will be inspected:
All tubes in the region of the leaker considered to reside within the high stress boundary.
A sample of tubes in like high stress regions in the affected leg (per management decision).
2 If the tube is not located in one of the known high stress areas, then the following tubes will be inspected:
A 5% random sample of the unplugged tubes in the affected leg will be inspected.
Further expansion will be performed in accordance with the supplementary sample criteria contained in the Palisades Technical Specifications in addition to the testing described in No. 1 above.
This inspection plan, in conjunction with the administrative leak rate limit of 0.05 gallons per minute (gpm), provides adequate control in the event of a tube leak prior to replacement of the steam generators.
Consumers Power Company performed the last Technical Specification required tube wastage inspections between December 4, 1987 and January 4, 1988.
Plant Technical Specification 4.14.1 allows a 30-month interval between inspections, providing the mean degradation increase for the previous steam generator inspection interval was less than +1%.
In 1987 this criteria was met; thus, the next required inspection must begin prior to July 4, 1990.
In light of the steam generator replacement outage which is scheduled to begin in September, 1990, Consumers Power Company requests the NRC grant Palisades a one-time exemption from this inspection for the following reasons:
- 1.
The results of the last Technical Specification inspection indicated both wastage and IGA degradation mechanisms were stable, a trend which has continued since the early 1980s.
- 2.
The recent tube leaks (since December 1987) have not evolved from areas of known degradation.
Hence, these tubes would have a low probability of being detected during a Technical Specification inspection.
- 3.
Since the December 1987 inspection Palisades has conducted four additional inspections due to tube leaks (August 1988, December 1988, February 1989 and October 1989).
The inspections have focused on the regions of current concern and represent a significant population of tubes (in August 1988 approximately 48% of the tubes were inspected and in October 1989 approxi-mately 18% were inspected).
OC1289-0013-NL02
Nuclear Regulatory Commission Palisades Nuclear Plant S/G Tube Inspection January 4, 1990
- 4.
Consumers Power Company is operating with an administrative limit of 0.05 gpm, primary to secondary system leakage which provides considerable 3
margin to the 0.3 gpm limit permitted by Plant Technical Specification 3.1.5.d.
In four shutdowns due to tube leakage since December 1987 the plant has been taken off-line prior to reaching the Technical Specification limit.
- 5.
The occupational radiation exposure required to perform the Technical Specification inspection has typically been 32 manrem.
For these reasons and because of the short time interval between July 4, 1990 and the steam generator replacement outage (2 months), we do not believe the required inspection to be prudent or necessary.
Kenneth W Berry Director, Nuclear Licensing CC Administrator, Region III, USNRC NRC Resident Inspector - Palisades OC1289-0013-NL02