ML17286B070
| ML17286B070 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 09/18/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17286B069 | List: |
| References | |
| NUDOCS 9110070163 | |
| Download: ML17286B070 (6) | |
Text
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+**y4 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.
95 TO FACILITY OPERATING LICENSE NO. NPF-21 WASHINGTON PUBLIC POWER SUPPLY SYSTEM NUCLEAR PROJECT NO.
2 DOCKET NO. 50-397
1.0 INTRODUCTION
By letter dated December 12, 1988 (G02-88-264),
Washington Public Power Supply System submitted a request for changes to the Technical Specifications (TS) for Nuclear Project No. 2.
The proposed changes would modify the Radioactive Gaseous Effluent Monitoring Instrumentation Table 3.3.7.12-1 of the technical specifications to allow operation of the main condenser off-gas treatment system without the associated action statement when one of the two redundant hydrogen monitors is inoperable.
Presently, both hydrogen monitors must be operable.
In the event of a failure or the need to perform maintenance necessitating shutdown of one monitor, the associated action statement requires sampling and analysis of the process stream at a minimum of eight hour intervals.
2.0 EVALUATION Hydrogen and oxygen are produced in a BWR by the radiolysis of water.
The hydrogen and oxygen produced, along with fission product and other noncon-densible
- gases, are removed from the. main condenser by a steam jet air ejector and exhausted to the off-gas treatment system.
A catalytic recombiner is provided in the off-gas treatment system to recombine hydrogen and oxygen.
Hydrogen concentration upstream of the recombiner is kept below the flammable limit (4 volume percent) by steam dilution.
Two parallel independent hydrogen analyzers measure the hydrogen content of the off-gas process flow downstream of the recombiner and off-gas condenser.
The hydrogen concentration measured in volume percent is indicated and recorded in the control room.
The hydrogen analyzer output is also provided to an independent alarm annunciator for high hydrogen concentration.
Calibration checks are accomplished automatically at periodic intervals by isolating tITe off-gas process line and admitting a calibration gas.
The main condenser vacuum provides the motive force to draw the sample from the off-gas process line through the analyzers.
The Washington Public Power Supply System Nuclear Plant No.
2 (WNP-2) Final Safety Analysis, Report (FSAR) states that the pressure boundary of the off-gas treatment system is designed to be detonation resistant.
The system design eliminates detonation sources so that a detonation is highly unlikely, even in the event of a recombiner failure.
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This evaluation is based on the guidance contained in Standard Review Plan (SRP) 10.4.2.
This SRP directs that, if there is a potential for explosive mixtures to exist, the off-gas system should be designed to withstand the effects of an explosion and provide instrumentation to detect and annunciate the buildup of potentially explosive mixtures.
Dual instrumentation is prescribed if the system is not designed to withstand the effects of a hydrogen/oxygen explosion.
The proposed amendment to the WNP-2 TSs permits operation of the main condenser off-gas treatment system with one of two installed hydrogen analyzers operable without entering the associated action statement.
This action statement currently allows operation of the main condenser.
off-gas system to continue for up to 30 days with one or more hydrogen monitors inoperable.
In this situation, the action statement requires grab samples of the off-gas process stream be collected at least once every four hours (eight hours if recombiner temperature and thermal power have not changed) and analyzed for hydrogen within the following four hours.
The proposed TS change would only require grab samples and analysis when no hydrogen monitor is operable.
It is the licensee's position that the required grab samples provide no enhancement to plant operation or safety with one or more hydrogen monitors in operation.
The NRC staff has reviewed and agrees with the licensee's position.
Since the WNP-2 FSAR states that the pressure boundary of the off-gas treatment system is designed to be detonation resistant, only a single hydrogen monitor is necessary to meet the guidance of the SRP to indicate hydrogen concentration and alarm a potentially explosive condition.
The proposed TS amendment satisfies the SRP guidance and provides adequate assurance that a means of detecting an explosive hydrogen concentration will be available whenever the main condenser off-gas system is in operation.
The staff finds the proposed TS amendment acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Washington State official was notified of the proposed issuance of the amendment.
The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 or change a surveillance requirement.
The NRC staff has determined that the amendment involves no significant increase in the amounts, and no signifi-cant 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 amendment involves no significant hazards consideration, and there has been no public comment on such finding (55 FR 6125).
Accordingly, the amendment meets 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 amendment.
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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 amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
S.
Jones Date:
September 18, 1991
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