ML19341A408
| ML19341A408 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 12/29/1980 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19341A407 | List: |
| References | |
| NUDOCS 8101230453 | |
| Download: ML19341A408 (2) | |
Text
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o UNITED STATES
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NUCLEAR REGULATORY COMMISSION o
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WASHINGTON, D. C. 20555
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 52 TO PROVISIONAL OPERATING LICENSE NO. DPR-19 AND AMENDMENT NO. 46 TO FACILITY OPERATING LICENSE NO. DPR-25 DOCKET NOS. 50-237 AND 50-249 yJTRODUCTION By letter dated December 5, 1980, the Commonwealth Edison Company (CECO) proposed a change to the Technical Specifications for Dresden Station Units No. 2.and 3.
The proposed change would permit the plant chimney monitoring system to be taken out of service for up to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> with the Units operating while modifications are being made to the chimney monitoring system to meet NRC requirements.
BACKGROUND In response to the NRC staff review of the Three Mile Island accident, the staff, by letter dated October 30, 1979, required CECO to install noble gas monitors with an extended range. These monitors shall be designed to function during accident conditions and normal operating conditions.
By letter dated January 1, 1980, Ceco committed to install the high range monitors and implemented interim methods of quantifying radioactive effluent releases should the existing instrumentation go off scale.
EVALUATION The installation of the extended range noble gas monitors requires that the existing noble gas monitors, which samples gas being exhausted through the plant chimney, be removed from service while the new monitors are being installed.
The plant chimney monitors sample the gaseous effluent exhausted from the reactor building. The main source of radioactivity in this exhaust stream is non-condensible gases removed from the main condensers by the steam jet air ejectors. The offgas from the air ejectors is monitored by the offgas monitors and then passed through the augmented offgas system to provide additional holdup time to allow the decay of the shorter lived radioactive halogens and noble gases. The gases are then exhausted through the stack after monitoring by the chimney monitor. Therefore, the main source of gaseous effluent to the plant chimney is monitored by the offgas monitors at the steam jet air ejectors and then by the chimney monitor after passing through the augmented offgas system.
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. CECO proposes to operate for up to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> with the plant chimney gas sampling system out of service. During the period that the plant chimney monitor is.out of service, CECO has proposed to operate with three additional limiting conditions for operation in the Unit 2/3 Technical Specifications. These conditions provide additional assurance that an increase in the release rate of gaseous radioactive effluent during the period that the plant chimney is out of service will be detected. The additional conditions proposed are:
- 1) The chimney monitor may be removed only if both units are at steady state conditions with their augmented off-gas systems in service; 2) A chimney release rate will be extrapolated from the offgas monitor readings.
In extrapolating from the offgas monitor reading to the chimney release rate, no credit will be taken for the charcoal adsorbers in the augmented offgas system. The chimney release rate, as indicated.by the offgas monitors, will be maintained below the existing chimney release limit of Specification 3.8.A.2.a; and 3) Both off;as monitors on Units 2 and 3 must be operable.
We have reviewed CECO's proposed operation with the chimney monitor out of service for up to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. We have determined that the additional technical specifications proposed by CECO during the interim period will provide adequate assurance that radioactive releases during the short period of steady state operation will be promptly detected and adequately monitored.
We conclude that operation in the proposed manner is acceptable and provides an equivalent level of protection to the chimney monitors.
ENVIRONMENTAL CONSIDERATIONS We have determined that these amendments do not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that these amendments involve an action which is insignificant from the standpoint of environmental impact and pursuant to 10 CFR 651.5(d)(4) that an env?ronmental impact statement, or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of '.hese amendments.
CONCLUSION We have concluded:
(1) because the amendments do not involve a significant increase in the probability of consequences of accidents previously considered and do not involve a significant decrease in a safety margin, the amendments do not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulations and the issuance of these amendmer M will not be inimical to the common defense and security or to the health w I safety of the public.
Date:
December 29, 1980 i
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