ML20057F318
| ML20057F318 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 10/06/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20057F316 | List: |
| References | |
| NUDOCS 9310150127 | |
| Download: ML20057F318 (3) | |
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4 UNITED STATES j
NUCLEAR REGULATORY COMMISSION I
E WASHINGTON, D.C. 20E0001 A...../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.1R9TO FACILITY OPERATING LICENSE DPR-57 AND AMENDMENT N0.128 TO FACILITY OPERATING LICENSE NPF-5 I
1 GEORGIA POWER COMPANY. ET AL.
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EDWIN I. HATCH NUCLEAR PLANT. UNITS 1 AND 2 l
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DOCKET NOS. 50-321 AND 50-366 i
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1.0 INTRODUCTION
By letter dated June 28, 1993, Georgia Power Company, et al. (the_ licensee),
i proposed license amendments to change the Technical Specifications (TS) for i
the Edwin I. Hatch Nuclear Plant, Units I and 2.
The proposed changes would revise Unit 1 TS 3.7.A.4 and Unit 2 TS 3.6.4.1, and their associated Bases, to i
allow one or more suppression chamber-drywell vacuum breakers to.open during surveillance testing or when performing their intended function without considering them inoperable.
t 2.0 EVALUATION
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Both Hatch Units 1 and 2 primary containments are equipped with vacuum breakers that are designed to automatically allow differential pressure to be i
relieved between the suppression chamber and drywell during accident conditions.
The accident of concern which requires the breakers' operability is the loss-of-coolant accident (LOCA). The requirement (as stated in Unit I f
TS 3.7.A.4 and Unit 2 TS 3.6.4.1) for all vacuum breakers to be operable and closed ensures that the steam from a postulated LOCA is directed through the vent lines and is discharged underwater in the suppression chamber where it is condensed. This process would lead to accumulation of noncondensible gases which could pressurize.the suppression chamber until it equalizes with the drywell pressure. 4 Subsequently, steam could condense in the drywell due to subcooled emergency core cooling system water flow from the break or manual initiation ~.of the drywell spray system. This would cause a differential pressure to' develop between the suppression chamber and the drywell. The vacuum breakers are designed to automatically relieve this differential pressurc to protect the drywell.
As stated above, Unit 1 TS 3.7.A.4 and Unit 2 TS 3.6.4.1 require all suppression chamber-drywell vacuum breakers to be operable and closed.
I However, certain normal operations such as: (1) the Hatch Unit 2 functional l
test of the hydrogen recombiner system which is required by TS 4.6.6.2.a i
(Unit I does not have a hydrogen recombiner system), and (2) inerting the i
containment during startup and deinerting during shutdown, can result in the opening of one or more of the vacuum breakers. Such occurrences place the A
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- plant in situations in which the TS requirements are not met, although the j
breakers are operating as designed and fully capable of fulfilling their intended safety function. A discussion of the above situations is provided below.
2.1 Hydrocen Recombiner Test Performance of a functional test of the Hatch Unit 2 hydrogen recombiner system is required by TS 4.6.6.2.a.
During this periodic testing, drywell atmosphere is drawn into the hydrogen recombiner reaction chamber and discharged to the suppression chamber.
During normal operation, there is not sufficient hydrogen and oxygen to cause recombination. Thus, there is no resultant water, and gas is discharged to the suppression chamber.
This causes an increase in the suppression chamber pressure relative to the drywell pressure which is relieved by the automatic opening of one or more of the suppression chamber-drywell vacuum breakers.
In the situation discussed above, the vacuum breakers are not inoperable or stuck open when they open in order to perform their safety-related function of relieving the pressure from the suppression chamber to the drywell. This test involves operating the recombiner for approximately 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> and is performed once every 6 months on each recombiner.
Following completion of the test, the plant operators are required, by plant procedures, to verify that the vacuum -
breakers have reclosed.
2.2 Inertino and deinertina durina startuo and shutdown During inerting, nitrogen is fed into the suppression chamber which increases the pressure of the suppression chamber atmosphere. When the differential pressure between the suppression chamber and the drywell reaches a certain limit, one or more vacuum breakers will open allowing the nitrogen to pass into the drywell and, thus, reducing the oxygen concentration. The drywell is then vented to maintain its pressure within acceptable limits. During deinerting, the same process is used except air is used in lieu of nitrogen.
Following completion of the test, the plant operators are required, by plant procedures, to verify that the vacuum breakers have reclosed.
Inerting and deinerting are only performed during startup and shutdown for brief periods of time. The probability of a LOCA occurring during one of these brief periods is extremely small.
However, if a LOCA were to occur, the drywell pressure will increase which would force the vacuum breaker back to its closed position, thus, eliminating the bypass leakage path.
Based on the above evaluations, the staff finds that the proposed TS revisions have no adverse impact on safety, do not pose an undue risk to public health and safety, and therefore, are acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Georgia State official was notified of the proposed issuance of the amendments. The State official had no comments.
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4.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to the installation or use of facility components located within the restricted area as defined in 10 CFR Part 20.
The NRC 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 (58 FR 39051 dated July 21, 1993).
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 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 Contributnr:
E. Wang K. Jabbour Date: October 6, 1993 j
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