ML17332A274
| ML17332A274 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 08/23/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17332A273 | List: |
| References | |
| NUDOCS 9408300114 | |
| Download: ML17332A274 (4) | |
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0 4 ***0 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 180 TO FACILITY OPERATING LICENSE NO.
DPR-58 AND AMENDMENT NO. 164 TO FACIL TY OPERATING ICENSE NO.
DPR-74 INDIANA MICHIGAN POWER COMPANY DONALD C.
COOK NUCLEAR PLANT UNIT NOS.
1 AND 2 DOCKET NOS.
50-315 AND 50-316
- 1. 0 INTRODUCTION By letter dated November 15,
- 1993, the Indiana Michigan Power Company (the licensee) requested amendments to the Technical Specifications (TS) appended to Facility Operating License Nos.
DPR-58 and DPR-74 for the Donald C.
Cook Nuclear Plant, Unit Nos.
1 and 2.
The proposed amendments would modify the TS for the ice condenser ice bed.
Specifically, the surveillance requirement interval in TS 4.6.5. 1.b, would be changed from 9 months to 18 months.
TS 4.6.5.1.b.
requires:
performance of chemical analyses to verify sufficient boron concentration in the ice and appropriate pH, weighing a representative sample of ice baskets to verify sufficient weight, and visual inspection of flow passages for blockage, The licensee stated that improvements in ice bed inspection results due to modified maintenance techniques and design changes that have been implemented since 1984 provide adequate assurance that the ice condenser can meet its design function without performing the surveillances on a 9-month frequency, Also, increasing the surveillance interval would reduce the stresses put on the baskets and their supports due to repeated weighing evolutions.
2, 0 EVALUATION Currently, TS 4.6.5. I.b. requires three aspects of the ice condenser ice bed to be checked once every 9 months.
The proposed change would require the performance of the surveillances every 18 months instead of every 9 months.
The change is proposed in order to decrease the number of containment entries required during power operations.
An 18-month surveillance would allow verification of ice basket boron concentrations,
- weights, and flow area blockage during refueling outages.
In addition, increasing the surveillance interval would reduce the stresses put on the baskets and their supports due to repeated weighing evolutions.
The first surveillance, TS 4.6.5. I.b. 1, requires a chemical analysis to verify that at least nine representative samples of stored ice have a boron concentration of at least 1800 ppm (the boron being in the form of sodium tetraborate),
and a
pH of 9.0 to 9.5 at 25'C.
The licensee has st'ated that 9408300ii4 940823 PDR ADOCK 05000315 P
the borated water source used to make the ice is sampled to verify that the boron concentration and pH levels are met.
Also, the licensee reviewed ice condenser basket boron concentration and pH sample data for Units 1 and 2
since 1986 and identified no problems in meeting this surveillance requirement.
In addition, NUREG-1431, "Standard Technical Specifications, Westinghouse Plants,"
issued September
- 1992, proposed an 18-month frequency for the surveillance of boron concentration and pH.
The bases in NUREG-1431 state that the 18-month frequency was based on the following:
a.
Long-term ice storage tests have determined that the chemical composition of the stored ice is extremely stable; b.
Operating experience has demonstrated that meeting the boron concentration and pH requirements has never been a problem; and c.
Someone would have to enter the containment to take the sample,
- and, if the unit is at power, that person would receive a radiation dose.
Based on the above, the proposed surveillance interval extension for subsection 1 of TS 4.6.5. l.b is acceptable.
The second surveillance, TS 4.6,5. I.b.2, requires weighing a representative sample of ice baskets and verifying that each contains a minimum weight of ice.
The specification also contains specific guidance on selecting a
representative
- sample, level of confidence requirements, and resampling requirements if individual baskets do not meet required weights.
The licensee reviewed licensee event reports back through 1978 for this surveillance.
Although eight occurrences were noted where some portion of this surveillance was not met, the licensee has since taken corrective actions.
These actions include installing a programmable defrost controller for air handling units to ensure that heat loads are distributed evenly, installing debris screens to preclude, clogging of duct work, and flow balancing the duct work to distribute cooling more evenly to the crane wall to reduce localized sublimation rates.
Haintenance techniques were also enhanced to increase the ice weights in baskets to ensure minimum TS requirements would be met without having to shut down the reactor during the mid-cycle surveillance to replenish ice inventory.
Weekly tours by operations personnel have also been implemented to monitor system performance.
In addition, existing surveillance 4.6.5. I.a. requires verification of an adequately low ice bed temperature every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
The licensee assessed the need for increasing the minimum ice bed weights to support the increased surveillance interval and determined that it was unnecessary, as previous weighings through 1986 required no mid-cycle ice additions to meet surveillance requirements.
When the Technical Specifications for the ice bed were developed, the staff included a level of conservatism to account for expected variances in sublimation rates.
The bases as issued for D.C.
Cook Unit 1 state:
"The minimum weight figure of 1220 pounds of ice per basket contains a
ION conservative allowance for ice loss through sublimation which is a factor of 10 higher than assumed for the ice condenser design.
In the event that observed sublimation rates are equal to or lower than design predictions after three years of operation, the minimum ice baskets weight may be adjusted downward.
In addition, the number of ice baskets required to be weighted each 18 months may be reduced after 3 years of
operation if such a reduction is supported by observed sublimation data."
In
- addition, the staff has extended the ice bed surveillance interval where observed sublimation rates have supported the change.
Based on the licensee's improvements to the ice condenser, the existing surveillances and tours, and that the request is consistent with previous staff positions, we find the proposed surveillance interval extension for subsection 2 of TS 4.6.5. I.b to be acceptable.
The third surveillance, TS 4.6.5, I.b.3, requires verification by visual inspection that flow passages in the ice condenser have less than the specified level of frost or ice accumulation.
A licensee review indicated several occurrences between 1983 and 1988 where flow passage requirements were not met, but assessments performed found that none of the degradations would have prohibited the ice condenser from performing its design functions.
Since there have been no further failures to meet the surveillance requirements after
- 1988, the design and maintenance changes discussed above may have had some effect in improving the performance of this aspect of the ice condenser.
In addition the licensee has implemented new methods to perform localized defrosting of the ice condenser bays which has reduced frost buildup on the ice condenser lattice framework along the crane and containment walls.
Based on the licensee's improvements to the ice condenser, the existing surveillances and tours, and the consistent satisfactory performance for the last three cycles, we find the proposed surveillance interval extension for subsection 3 of TS 4.6.5.1.b to be acceptable.
A typographical error in Bases section 3/4.6.5. I of both units has been corrected changing "weighted" to "weighed."
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Michigan State official was notified of the proposed issuance of the amendments.
The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change surveillance requirements.
The staff has determined that the amendments involve no significant increase in the amounts,'nd 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 the amendments involve no significant hazards consideration and there has been no public comment on such finding (58 FR 67849).
Accordingly, the amendments meet 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 the amendments.
5.0 CONCLUSION
The staff has concluded, based on the considerations discussed
- above, that:
(I) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed
- manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
John B. Hickman pate.
August 23, 1994