ML20237L440
| ML20237L440 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 08/27/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20237L436 | List: |
| References | |
| NUDOCS 8709080401 | |
| Download: ML20237L440 (3) | |
Text
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'%J SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.106 TO PROVISIONAL OPERATING LICENSE NO. DPR-20 CONSUMERS POWER COMPANY PALISADES PLANT DOCKET NO. 50-255 INTRODUCTION By letter dated September 28, 1984, Consumers Power Company (the licensee) submitted proposed changes to the Palisades Technical Specifications concerning steam generator inservice inspections.
The proposed changes included, in part, a proposal that the maximum time interval allowed between inspections be changed from the current value of 24 calendar months to 30 calendar months.
At the staff's request, the licensee amended its proposal concerning the maximum inspection interval by letter dated June 5, 1987.
Under the revised proposal, the maximum interval can be extended from 24 to 30 calendar months if the results of the previous inservice inspection indicate that the mean degradation increase between inspections is less than 1L This Safety Evaluation addresses the proposed steam generator inspection interval extension as amended by the licensee's June 5, 1987, letter.
The other changes proposed by the licensee's September 28, 1984, application are i
being handled separately.
I DISCUSSION In the basis for the proposed inspection interval (letter dated September 28, 1984), the licensee stated that its intent is to conduct an inspection at each scheduled refueling outage.
Because of long outage durations which have been experienced at Palisades, the licensee concludes that a 30-month rather than a 24-month maximum inspection interval is appropriate in order to avoid unscheduled outages for inspection.
The results of the most recent inspections of the Palisades steam generator, performed in 1985, were reported to the NRC staff by letter dated January 27, 1986.
The results of the 1985 inspections revealed essentially no further degradation of the A or B steam generator (i.e., less than 1% mean increase in the indicated depth of ECT indications) relative to what was observed during the previous inspections performed in 1983.
The licensee attributes this good performance to strict adherence to secondary water purity limits and maintaining the secondary side of the steam generators in wet lay-up as much as possible during non-operating conditions.
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i EVALUATION Ideally, steam generator inspection intervals should be of sufficiently short duration such that additional degradation during the interval does not excessively degrade tube integrity prior to the next inspection.
Palisades experienced no observable progression of degradation between inspections performed in 1983 and 1985, respectively.
Furthermore, since 1985, Palisades has operated eithout evidence of primary to secondary leakage.
Ba.;ed on the above, and extension of the current interval from a maximum of 24 to 30 calendar months is not expected to result in significant further degradation
'of the steam generator tubing prior to the next inservice inspection.
- However, even.should degradation unexpectedly accelerate over previously observed rates, the likely consequence would be a small primary to secondary leak as evidenced by operating experience.
Allowable leak rate limits in the Technical Specifications ensure that the plant will be shutdown in a timely manner before excessive leakage of radioactive primary coolant is released.
Similarly, the NRC staff concludes that an extension of future inspection intervals from a maximum of 24 to 30 months is acceptable provided that the previous inspection revealed essentially no progression (i.e., 5 1%) in degradation during the previous operating interval.
Should the degradation rate equal or exceed 1%, then the subsequent inspection interval would be limited to the current limit of 24 months.
In eddition, the licensee would be required under its existing Technical Specifications to obtain NRC approval of operating allowances to be incorporated into the plugging limits to account for the expected additional degradation prior to the next scheduled inspection, thus providing additional assurance that the operating interval is consistent with observed degradation rate and plugging limit.
Based on the above, the staff concludes the 30-month inspection interval proposed in the licensee's letter dated September 28, 1984, and subsequently amended in the licensee's letter dated June 5, 1987, is acceptable.
ENVIRONMENTAL CONSIDERATION This amendment involves a change in an inspection or surveillance requirement.
We have determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has been no public comment on such finding.
Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.
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1 CONCLUSION s
We have concluded, based on the considerations discussed above, that (1) there
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is reasonable assurance that the health and safetytof the public will not be endangered by operation in the proposed manner, and (2) sucrisqctivities will be conducted in compliance with the Commission's regulations,'and the issuance of the amendment will not be inimical to the common defense andssecurity or to the health and safety of the public.
1 Date: August 26, 1987 Principal Contributor:
E. Murphy l.
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