ML20237E142
| ML20237E142 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 08/25/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20237E135 | List: |
| References | |
| NUDOCS 9808280277 | |
| Download: ML20237E142 (3) | |
Text
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UNITED STATES l
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NUCLEAR REGULATORY COMMISSION p
2 WASHINGTON, D.C. 30666 4 001 s...../
l SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 168 TO FACILITY OPERATING LICENSE NPF-35 AND AMENDMENT NO.160 TO FACILITY OPERATING LICENSE NPF-52 DUKE ENERGY CORPORATION. ET AL.
I CATAWBA NUCLEAR STATION. UNITS 1 AND 2 j
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DOCKET NOS. 50-413 AND 50-414 1
1.0 INTRODUCTION
By letter dated April 8,1998, Duke Energy Corporation, et al. (the licensee), submitted a request for changes to the Catawba Nuclear Station, Units 1 and 2, Technical Specifications (TS). The requested changes revise TS Section 3/4.6.5.1 regarding the ice bed of the ice I
condenser and the associated Bases Section 3/4 6.5.1.
2.0 DISCUSSION AND EVALUATION The ice condenser design and performance analysis are described in Section 6.7 of the Catawba Updated Final Safety Analysis Report. The primary function of the ice condenser is the absorption of thermal energy released abruptly in the event of a loss-of-coolant accident or steamline break accident, thereby limiting the initial peak pressure in the containment.
TS 3/4.6.5.1, the subject of the licensee's amendment request, specifies the conditions of the ice bed of the ice condenser.
By Amendment Nos. 83 (for Unit 1) and 77 (for Unit 2), dated February 20,1991, the staff imposed minimum required ice weight: 2,475,252 pounds total for each ice condenser, i
1273 pounds for each ice basket in a condenser. The staffs associated safety evaluation states that these limits were derived from the assumed 2,132,000 pounds (i.e.,1097 pounds for each of the 1944 baskets) of ice at the onset of a postulated accident, adding a 15 percent j
conservative allowance for ice loss through sublimation in an 18-month surveillance interval, and adding a 1.1 percent conservative allowance to account for weig'ning instrument errors.
Over the past years of operation of both units, the licensee has collected approximately 40,000 ice basket weight records and stored the data in the Ice Condenser Data Management System (ICEMAN). Using the individual ice basket sublimation rate, the licensee calculated an overall average observed sublimation rate for each ice condenser. In calculating the average sublimation rate, the licensee ignored negative sublimation rates (e.g., for baskets near the annulus wall that actually gained weight) by simply setting them to zero. As a result, the average of all positive sublimation rates for the Units 1 and 2 ice condenser is 0.0810 and 0.0728 pounds / day / basket. ICEMAN has been validated by the licensee over time to correct!y 9808280277 990825 PDR ADOCK 05000413 P
PDR L_____-__--____-____________-__
I l i predict ice basket weight. The licensee further applied a safety factor of 2, thus conservatively doubling the sublimation rate; therefore, the sublimation allowance for each ice condenser is:
Allowance for cach basket = (Sublimation Rate per basket) x (Days in Fuel Cycle) x 2 l
For an 18-month fuel cycle, the allowance for the Units 1 and 2 condenser is calculated to be 89.10 and 80.08 pounds per basket. Based on this, the licensee proposed to use 90 pounds l
sutumation allowance per basket, instead of the 15 percent (i.e.,164 pounds) sublimation allowance assumed in the current requirement. The weighing error of 1.1 percent remains unchanged. Therefore, the new minimum ice weight per basket at the beginning of an 18-month surveillance intervalis:
Minimum ice weight = 1,097 x 1.011 + 90 = 1,199 pounds l
The licensee proposed to revise Section 4.6.5.1.c to reflect this calculation. The licensee also j
proposed to revise Section 3.6.5.1.d to reflect the totalice weight in 1944 baskets to be l
2,330,856 pounds. Bases Section 3/4.6.5.1 would similarly be changed to reflect the new l
calculations.
l The NRC staff has reviewed the licensee's submittalin detail and found that the licensee had
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app?ied appropriate conservatism in the calculation of sublimation allowance. Therefore, the staff determines that the new requirements are acceptable.
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3.0 STATE CONSULTATION
1 in accordance with the Commission's regulations, the South Carolina State official, Mr. Virgil Autrey, was notified of the proposed issuance of the amendments. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change requirements with respect to installation or use of a facility l
component located within the restricted area as defined in 10 CFR Part 20 and change i
surveillance requirements. The NRC staff has determined that the amendments involve no significant increase in the amounts, 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 1
l occupational radiation evposure. The Commission has previously issued a proposed finding l
that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (62 FR 25107 dated May 6,1998). 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 environmentalimpact statement or environmental assessment need be prepared in connection with the issuance of the i
amendments.
5.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that: (1) 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 Contributors: P. Tam K. Campe Date:
August 25, 1998 1
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