ML20202F216
| ML20202F216 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 04/01/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20202F188 | List: |
| References | |
| NUDOCS 8604140126 | |
| Download: ML20202F216 (3) | |
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8 NUCLEAR REGULATORY COMMISSION n
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WASHINGTON, D. C. 20665
,o SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N0.53 TO FACILITY OPERATING LICENSE NPF-9 AMENDMENT N0.34 TO FACILITY OPERATING LICENSE NPF-17 DUKE POWER COMPANY l
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DOCKET NOS. 50-369 AND 50-370
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McGUIRE NUCLEAR STATION, UNITS 1 AND 2 INTRODUCTION By letter dated January 21, 1986, and revised March 17, 1986, Duke Power Company (the licensee) requested a revision to Technical Specification 4.6.1.2d to permit an alternate means of local leak testing certain mechanical containment penetration diaphragm valves in the ice condenser refrigeration system without draining the glycol mixture from the system. Because the alternate test would use the glycol mixture instead of air or nitrogen as the testing medium, an exemption to Section III C.2(a) of Appendix J to 10 CFR 50 is associated with the request and is addressed concurrently by the NRC staff by separate document. The information submitted by the licensee's letters dated September 24, 1985, and February 14, 1986, regarding the exemption request is also used by the NRC staff for its review of the licensee's request for technical specification changes.
EVALUATION Surveillance Specification 4.6.1.2 of the facility Technical Specifications requires that primary containment leak rates periodically be demonstrated in conformance with criteria specified in Appendix J of 10 CFR 50.
Sub-paragraph d of this Specification states that Type B and C tests (local tests of penetrations and valves) are to be conducted with gas at a specific pressure and test interval with three indicated exceptions.
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These amendments add, as a fourth exception to Subparagraph d:
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" Type C tests performed on containment penetrations M372, M373 j
without draining the glycol-water mixture from the seats of their diaphragm valves (NF-228A, NF-2338, and NF-234A), if meeting a zero indicated leakage rate (not including instrument error) for the diaphragm valves. These tests may be used in lieu of tests which are otherwise required by Section III C.2(a) of 10 CFR Part 50, Appendix J to use air or nitrogen as the test medium. The above required test pressure (Pa) and test interval are not changed by this exception."
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Section III C.2.(a) of Appendix J to 10 CFR 50 requires that the leakage rate testing of containment isolation valves be conducted using air or nitrogen as the testing medium. The licensee has requested a technical specification change and an exemption from this requirement for penetrations M-372 and M-373.
The local leakage rate test (Type C test) would be performed without draining the glycol from the seats of the diaphragm valves in these penetrations.
The McGuire design includes an ice condenser to suppress the peak accident pres-sure in the reactor containment building.
The ice condenser is refrigerated by recirculating a 50% - 50% mixture of ethylene glycol and water through a i
series of air handling units located inside the containment building and chiller units located in the auxiliary building. Typically, draining, testing and refilling the system requires 24 to 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> of downtime for the ice condenser refrigeration system. This extended downtime potentially diminishes the amount of ice in the baskets. Draining the glycol consumes a significant number of manhours and creates toxic waste (glycol) which requires disposal.
As an alternative to draining approximately 200 gallons of glycol for each McGuire unit as is necessary to perform this test using gas, the licensee has proposed to test three diaphragm valves (NF-228A, NF-2338, and NF-234A) i without draining the glycol mixture from the valve seats. The leakage rate acceptance criterion that would be imposed on these diaphragm valves would i
be zero indicated leakage (not including instrument error).
In other words, the display device of the measurement system must read zero.
Otherwise, if the leakage rate is greater than zero, the penetration will be fully drained and the valves leak tested in accordance with Appendix J.
Historically, the staff has not accepted the use of a liquid (usually water) in place of air or nitrogen as a testing medium for Type C tests (i.e., local tests of containment isolation valves). This is because it has not been possi-ble to develop a sufficiently conservative yet practically useful, conversion factor for converting water leakage to an equivalent air leakage. However, for the proposed testing, no conversion factor is used; the acceptance criterion of zero leakage of glycol can be assumed to be equivalent te zero leakage of air, or, at worst, possibly a very small leakage of air. This is compared to the acceptance criterion provided by Appendix J for air tests, which is that the total of all local leakage rate tests must not exceed 0.6 La, where La is the maximum allowable leakage rate of the containment as a whole.
Thus, Appendix J does not impose leakage rate limits on individual valves, but rather on the total leakage rate for all valves and penetrations.. Therefore, the staff finds that an acceptance criterion of zero leakage of glycol, applied individually to each of the three valves is at least as conservative as the acceptance criterion of Appendix J.
The alternative method of testing with the glycol mixture also accomplishes the same underlying purpose as Appendix J,Section III C.(2)(a) because it provides a conservative assurance of continued leak-tight integrity of the three affected valves.
For these reasons, the staff finds that the use of the glycol mixture for the test medium under the conditions stated in revised Specification 4.6.1.2 is acceptable, i
. If a valve fails the zero leakage criterion, the licensee will proceed to fully drain the penetration and test the valves with air or nitrogen in accordance with Appendix J.
This is, of course, acceptable.
ENVIRONMENTAL CONSIDERATION These amendments involve changes to the installation or use of facility com-ponents located within the restricted area as defined in 10 CFR Part 20 and a change in surveillance requirement. The staff has determined that the amend-ments 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 exposure. The NRC staff has made a proposed determination that the amendments involve no sig-nificant hazards consideration, and there has been no public comment on such findings. Accordingly, the amendments meet the eligibility criteria for cate-gorical 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 these amendments.
CONCLUSION The Commission made a proposed determination that the amendments involve no significant hazards consideration which was published 'in the Federal Register (50 FR 6475) on February 24, 1986, and consulted with the state of North Carolina.
No public comments were received, and the state of North Carolina did not have any comments.
We have 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, and (2) such activities will be conducted in compliance with the Commission's regulations and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors:
Darl S. Hood, PWR Project Directorate #4, PWR-A J. Pulsipher, Mechanical Engineering Section, PWR-A Dated: April 1, 1986 l
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7590-01 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the Matter of
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)
DUKE POWER COMPANY
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Docket Nos.
50-369 (McGuire Nuclear Station.
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and 50-370 Units 1 and 2)
EXEMPTION PROVIDING FOR CONTAINMENT PENETRATION s
ItSTING USING GLYCUL I.
Duke Power Company (the licensee) is the holder of Facility Operating License No. NPF-9 and Facility Operating License No. NPF-17, which authorize the operation of the McGuire Nuclear Station, Units 1 and 2 (the facility) at steady state reactor power levels not in excess of 3411 megawatts thermal.
The facility consists of pressurized water reactors located in Mecklenburg County, North Carolina.
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II.
Section III C.2(a) of Appendix J to 10 CFR Part 50 which addresses the test pressure to be used in the performance of local leak rate tests for systems and components penetrating primary containment pressure boundary pro-vides: " Valves, unless pressurized with fluid (e.g., water, nitrogen) from a seal system, shall be pressurized with air or nitrogen at a pressure of Pa" (emphasisadded).Section II.H of 10 CFR Part 50, Appendix J, defines " Type C Tests" as tests intended to measure containment isolation valve leakage These valves help maintain the leak-tight integrity of the containment rates.
at design basis accident conditions.
III.
By letters dated September 24, 1985, and February 14, 1986, the licensee requested an exemption from the requirements of Section III C.2(a) of Appendix "8604080yf tf
J to 10 CFR 50, to provide for the use of glycol instead of air or nitrogen as the testing medium for the leakage rate testing of certain containment isolation valves in the Ice Condenser Refrigeration System. The requested exemption is for penetrations M-372 and M-373. The local leakage rate test (Type C test) would be performed without draining the glycol mixture from N
the seats of the diaphragm valves in these penetrations.
The design of the reactor containment building at McGuire includes an ice condenser to suppress the peak accident pressure. The ice condenser is refrigerated by recirculating a 50% - 50% mixture of ethylene glycol and water through a series of air handling units located inside the containment building and chiller units located in the auxiliary building. The licensee notes that draining, testing, and refilling the system typically requires 24 to 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> of downtime for the ice condenser refrigeration system. This extended downtime potentially diminishes the amount of ice in the baskets.
The licensee also notes that draining the glycol consumes a significant number of manhours and creates toxic waste (glycol) which has to be disposed.
As an alternative to draining approximately 200 gallons of gylcol as is necessary to perform this test in accordance with Appendix J, the licensee has proposed to test three diaphragm valves (NF-228A, NF-233B, and NF-234A) without draining the glycol mixture from the valve seats. The leakage rate acceptance criterion that would be imposed on these diaphragm valvet would be zero indicated leakage (not including instrument error).
In other words, the display device of the measurement system must read zero. Otherwise, if the leakage rate is greater than zero, the penetration will be fully drained and the valves leak tested in accordance with Appendix J.
O
o Historically, the staff has not accepted the use of a liquid (usually'
- water) in place of air or nitrogen as a testing medium for Type C tests (i.e.,
1 local tests of containment isolation valves). This is because it has not been possible to develop a sufficiently conservative, yet practically useful, con-l version factor for converting w'ater leakage to an equivalent air leakage.
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However, for the proposed testing, no conversion factor is used; the acceptance criterion of zero leakage of glycol can be assumed to be equivalent to zero leakage of air, or, at worst, possibly a very small leakage of air.
This is compared to the acceptance criterion provided by Appendix J for air tests, 1
which is that the total of all local leakage rate tests must not exceed 0.6 La, j
where La is the maximum allowable leakage rate of the containment as a whole.
l Thus, Appendix J does not impose leakage rate limits on-individual valves, but 1
t rather on the total leakage rate for all valves and penetrations. Therefore, i
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the staff finds that an acceptance criterion of zero leakage of glycol, applied individually to each of the three valves, is at least as conservative as the' acceptance criterion of Appendix J.
For this reason, the staff finds that the requested exemption is acceptable.
If a valve fails the zero leakage criterion, the licensee will proceed to fully drain the penetration and test the valves with air or nitrogen in accordance with Appendix J.
This is, of course, acceptable.
IV.
Accordingly, the Comission has determined that, pursuant to 10 CFR 50.12(a)(1) this exemption is authorized by law, will not present an undue risk to the public health and safety, and is consistent with the common i
defense and security. The Comission further determines that special circumstances, as provided in 10 CFR 50.12(a)(2)(ii), are present justifying i
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the exemption, namely that application of the regulation in the particular cir-4 cumstances is not necessary to achieve the underlying purpose of the rule.
The underlying purpose of the rule is to require local leak rate testing at periodic intervals of certain types of containment isolation valves to determine whether there has been degradation in the leakage characteristics of these valves which might adversely affect containment integrity. The proposed alternative test method is sufficient to achieve this underlying purpose in that it provides a conservative assurance of continued leak-tight integrity of the three affected.
valves, NF-228A, NF-233B and NF-234A.
Accordingly, the Commission hereby grants an exemption as described in Section III above from Section III C.2(a) of Appendix J of 10 CFR 50 to the extent that Type C tests for containment penetration numbers M-372 and M-373, i
performed without draining the glycol-water mixture from the seats of their diaphragm valves NF-228A, NF-2338 and NF-234A, and meeting a zero indicated leakage rate (not including instrument error) for these diaphragm valves, shall constitute an acceptable alternate to Type C tests using air or nitrogen as the test medium.
Pursuant to 10 CFR 51.32, the Comission has determined that the granting of this Exemption will have no significant impact on the environment (March 7, 1986, 51 FR 8053).
i This Exemption is effective upon issuance.
F THENUCgEAR ULATORY COMMISSION W
ga c n eputy Director Division of PWR Lice ng-A Datedatggthesda, Maryland this 31 day of March 1986.
DATED:
April 1, 1986 dMENDMENT N0.53 TO FACILITY OPERATING LICENSE NPF McGuire Nuclear Station, Unit 1 AMENDMENT NO 34 TO FACILITY OPERATING LICENSE NPF McGuire Nuclear Station, Unit 2 DISTRIBUTION:
. Docket File 50-369/370 NRC PDR Local PDR PRC System NSIC PWR#4 R/F BJYoungblood R/F MDuncan DHood HThompson OELD JPartlow BGrimes Edordan LHarmon WJones TBarnhart (8)
ACRS (10)
OPA LFMB VBenaroya JPulsipher 1