ML20195D549
| ML20195D549 | |
| Person / Time | |
|---|---|
| Site: | Waterford, 050382O  |
| Issue date: | 06/03/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20195D546 | List: |
| References | |
| NUDOCS 9906090198 | |
| Download: ML20195D549 (3) | |
Text
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t UNITED STATES j
j NUCLEAR REGULATORY COMMISSION WASHINGTON D.C. 20066-0001
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.151 TO FACILITY OPERATING LICENSF NO. NPF-38 ENTERGY OPERATIONS. INC.
WATERFORD STEAM ELECTRIC STATION. UNIT 3 DOCKET NO. 50-382
1.0 INTRODUCTION
l By application dated October 1,1998, as supplemented by letters dated March 25 and May 6, 1999, Entergy Operations, Inc. (the licensee), submitted a request for changes to the Waterford Steam Electric Station, Unit 3, Technical Specifications (TSs). The requested changes would i
modify TS 3.3.3.7.3 and Surveillance Requirement (SR) 4.3.3.7.3 for the broad range gas detection system. In addition, a change to TS Bases 3/4.3.3.7 has been included to support this change.
The proposed change will provide a new, more reliable broad range gas detection system to continuously monitor incoming control room air for the presence of a variety of toxic gases. The new system is more sensitive, has greater resolution, and is more stable.
The March 25 and May 6,1999, submittals provided additional information that did not change the initial proposed no significant hazards consideration determination.
2.0 EVALUATION The licensee has requested a change to TS 3.3.3.7.3, its Action Statement and SR 4.3.3.7.3, and Bases Section 3/4.3.3.7. The change is required to support the installat!on of a new broad range gas detection system. The changes are as follows:
In Limiting Condition for Operation 3.3.3.7.3, a footnote is added to stato entry into the action statement solely due to the automatic,2-minute background / reference spectrum check is not required.
In SR 4.3.3.7.3, a change is introduced to modify the channel functional test to account for the new instrument calibration procedures.
In Bases Section 3/4.3.3.7, " Chemical Detection System," a description of the new toxic gas (TG) detection system, its operation, and its calibration procedure is included.
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The licensee plans to install a new broad range gas monitor system known as Air Composition Monitors supplied by Telosense, Inc. The monitors use a Fourier Transform infrared analysis technique, which has the capability of measuring the concentration of all gases of concern with respect to habitability except chlorine. The licensee plans to continue monitoring chlorine gas levels with the existing chlorine system which meets the requirements of TS 3.3.3.7.1.
The new instrument requires a background / reference spectrum check to account for carbon dioxide and moisture in the air. The self-calibration check utilizes the plant instrument air system and lasts a maximum of 2 minutes at a variable frequency between 1 and 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. The plant instrument air system uses the atmosphere from the turbine building. During this time, the instrument cannot respond to an increase in TG levels and detection of a TG release is dependent on the redundant system. In the event that the redundant system is out of service, the control room will be without protection for a maximum of 2 minutes per hour during the self-calibration check. This creates a problem with verbatim compliance with TS 3.3.3.7.3 as currently written and necessitates the change stated above to address this scenario. The licensee's qualitative analysis, based on a quantitative risk assessment has shown that the likelihood of causing operator incapacitation, while one monitor is out of service for its 7-day allowed outage time, is negligible. Additional information provided by the licensee indicates that the impact on operator incapacitation is below the acceptable risk level in Regulatory Guide 1.174,"An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions i
on Plant-Specific Changes to the Licensing Basis." Therefore, interruption of the monitoring operation during the 2-minute calibration period will not affect the safety of the plant and entry into the action statement solely due to the automatic,2-minute background / reference spectrum j
check is not required.
The installation of the new cystem necessitates a change to SR 4.3.3.7.3 and Bases Section 3/4.3 3.7. Y,1e currently required manual calibration at a frequency of once per 7 days is deleted from SR 4.3.3.7.3, since the new instrument automatically calibrates at least once per 4-hour period. A channel check will be performed once every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to compare channel indications and to ensure that gross failure of the instrument has not occurred in addition, the introduction of a standard gas will become part of the channel functional test, which is consistent with the requirements of the new system. The background / reference spectrum check is set during the channel functional test such that both channels are not out of service simultaneously. The Bases will describe the new TG system, its operation, and its calibration.
The staff finds these changes acceptable in supporting the installation of the new TG monitoring system.
The licensee evaluated a potential unreviewed safety question with respect to the self calibration check, in the event of a slow TG release in the turbine building, the periodic self calibration could mask the increase in TG levels with each recalibration by raising the baseline to a higher TG concentration. The licensee completed a quantitative analysis that simulated this scenario over an approximately 1-year time period using site-specific meteorological data available. For each hour in the simulation, a toxic chemical accident was assumed to occur.
The monitors were biased by simulating the scheduled calibration with contaminated instrument air. In the case where neither monitor actuated when appropriate and the wind conditions had l
not shifted, the control room operators were assumed to be at risk and the probability of a toxic chemical accident occurring in that hour was added to a hazard probability sum. The licensee 4
determined that the annual probability of this scenario occurring is insignificant,3.6 x 10.
Based on these results, the staff concludes that this potential unreviewed safety question is
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3 satisfactorily resolved, since it has been demonstrated to involve insignificant risk to public health and safety.
Based on its evaluation, the staff finds that the licensee has adequately addressed the following concerns related to the installation of the new monitors: (1) in the event that the redundant detection system is out of service, the control room is without protection for a maximum of 2 minutes per hour duiing the background / reference check, and (2) the use of plant instrument air for the background / reference check could cause detection of the TG to be masked during a slow increase in TG levels. These concerns have been addressed and analyzed with results indicating negligible probability of operator incapacitation and of a potentially new malfunction of instrumentation. The staff concludes, therefore, that the TS changes associated with the installation of the new broad range gas detection system is acceptable.
4.0 STATE CONSULTATION
in accordance with the Commission's regulations, the Louisiana State official was notified of the proposed issuance of the amendment. The State official had no comments.
5.0 ENVIRONAENI61&ORSIDfJBHQN The amendment changes 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 surveillance requirements. The NRC staff has determined that the amendment involves 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 amendment involves no significant hazards consideration and there has been no public j
comment on such finding (63 FR 64114, November 18,1998). 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 1
prepared in connection with the issuance of the amendment.
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that (1) there is i
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 iegulations, 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: C. Lauron Date: June 3, 1999 a.
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