ML20085B515
| ML20085B515 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 07/30/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20085B512 | List: |
| References | |
| NUDOCS 9108020130 | |
| Download: ML20085B515 (3) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR dEGULATION REL ATED TO AMENDMEliT NO.157 TO FACILITY OPERAT!!iG LICENSE NO. OPP-53 AliD AMENDMENT f40.137 TO FACILITY OPEkATlHG LICENSE NO. DPR-69 BALTIMORE GAS AND ELECTRIC COMPANY CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT NOS 1 AND 2 DOCKET NOS. 50-317 AND 50-318
1.0 INTRODUCTION
By letter dated May 24, 1991, the Baltimor. Gas and Electric Company (the licensee) submitted a request for changes to the Calvert Cliffs Nuclear Power Plant, Unit Nos. I and 2 Technical Specifications (TS).
The requested changes would allow the usc. of the Mass Point method for conducting containment integrated leak rate tests (CILRT) and revises the test interval to be consistent with 10 CFR Part 50, Appendix J, requirements taking into account the current 24-month refueling cycles.
TS Surveillance Requirement 4.6.1.2 currently requires the exclusive use of ANSI N45.4-1972 to determine containment leakage rates. This standard provides two acceptable methods of CILRT calculations.
The first method is Point-to-Point and the second method is Total Time. The second method, currently being used by the licensee, calculates a series of leakage rates based on most recent data and the data taken at the start of the test.
Each successive calculated leakage rate is therefore based on a longer period of time. The hourly leakage rate is determined by applying a linear least square fit to the calculated leakage rates at each time point.
Technical Specification 4.6.1.2 also requires that three CILRTs be conducted at 40:10 month intervals during each 10 year service period.
Calvert Cliffs, as noted above, is on a 24-month fuel cycle which does not allow meeting this surveillance interval.
2.0 EVALVATION As noted by the licensee, advances in leakage rate testing subsequent to the issuance of both ANSI N45.4 and the Calvert Cliffs TSs have provided a newer method of evaluatlng test data called the Mass Point method.
The Mass Point method is described in ANS!/ANS 56.8 1987 and involves calculating the containment air mass at different times by application of the Ideal Gas Law.
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li. The data is then analyzed by the method of linear least squares. The slope of this line represents the rate of change of air mass with respect to time, which is the leakage rate.
The Nuclear Regulatory Commission (NRC) has amended 10 CFR Part 50, Appendix 0,
" Primary Containment Leakage Testing for Water-Cooled Power Reactors," to explicitly permit the use of the Mass Point statistical data analysis method (53 FR 45890) after recognizing the Mass Point method as an improved alternative method of calculating integrated leakage rates. Therefore, the NRC staff finds the proposed change to TS 4.6.1.2, which deletes the requirement to use the test methods and provisions of ANS1 N45.4-1972, acceptabic.
The modified TS will require that the criteria, methods, and provisions specified in Appendix J to 10 CFR Part 50 to be met which, as noted, allows the use of the Mass Point Method.
10 CFR Part 50, A'apendix J, also requires that the Type A test of the containment be performed periodically. These tests are to be scheduled as a set of three tests, at approximately equal intervals, during each 10-year service period, with the third test to coincide with the 10-year inservice inspections. The current TS Surveillance Requirement schedule, TS 4.6.1.2.a.
requires the Type A test to be conducted at 4010 month intervals during each ten year service period. This TS required schedule is readily adaptable for the previous 12 and 18 month fuel cycles at the Calvert Cliff s f acility.
Hcwever, the current 24 month fuel cycles do not provide for three tests within a 10-year service period with 40110 months between each test.
In a 24-month fuel cycle, the tests must be conducted every other refueling outage to be within the 30 to 50 month range allowed; however, this would require a minimum of 12 years to conduct the required set of three tests. The proposed revision will match the wording of 10 CFR Part 50, Appendix J, which requires only that the tests be conducted "at approximately equal intervals" during a 10-year service period. Typically, this would result in a test being conducted at intervals of four years, four years and two years over a ten year period. Therefore, the NRC staff finds the proposed change to TS 4.6.1.2a, which deletes the 40!10 month interval requirement is consistent with 10 CFR Part 50, Appendix J, and is acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Maryland State official was notified of the proposed issuance of the amendments. The State official had no comments.
3 4.0 EliVIRONMEtiTAL C0l4 SIDERATION The amendrents change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes the surveillance requirements.
The f3C staff has determined that the amendments involve 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 the amendments involve no significant hazards consideration, and there has been no public comment on such finding (56 FR 29269). 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 staterent or environmental assessment need be prepared in connection t) with the issuance of the amendnents.
5.0 CONCLUS10t1 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, (?) 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:
D. Mcdonald Date:
July 30,1991 P
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