ML19262C666
| ML19262C666 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 02/01/1980 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19262C661 | List: |
| References | |
| NUDOCS 8002150349 | |
| Download: ML19262C666 (2) | |
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((? - (h NUCLEAR REGULATORY COMMISSION UNITED STATES WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 47 TO PROVISIONAL OPERATING LICENSE NO. DPR-19 AND AMENDMENT NO. 41 TO FACILITY OPERATING LICENSE NO. DPR-25 COMMONWEALTH EDIS0N COMPANY DRESDEN NUCLEAR POWER STATION, UNIT NOS. 2 AND 3 DOCKET NOS. 50-237 AND 50-249 Introduction By letter dated January 4,1980, Commonwealth Edison Company (CECO) proposed changes to the Technical Specifications for Dresden Units 2 and 3.
The proposed changeswould allow the ECCS ring header snubbers to be inoperable in groups of up to three pairs at the same time until September 1,1980, so that the installation of suppression chamber support modifications can be accomplished.
Discussion and Evaluation There are six pairs of snubbers in the ECCS ring header support systems for Dresden Units 2 and 3.
The snubbers mitigate the effects of seismic motion of the torus ring header.
Plant modifications to the external support system for the suppression chamber (torus) now underway require that the ECCS ring header snubber attachments to the torus be removed in order to install torus external support saddles. An analysis has been performed to demon-strate the effect of removal of the snubbers on the response of the ring header for seismic events.
Using acceleration response spectra derived from the original ring header analysis, the new analysis demonstrates that, for normal operation plus operating basis earthquake (OBE) loading, stresses remain below code allowable stresses aven with all six pairs of snubbers inoperable. Therefore, the requirement that at least three pairs of snubbers be operable at all times is conservative with respect to the more severe analyzed condition of all snubbers inoperable.
Removing the snubbers from operability in the manner described does not encroach upon margin provided by the code. The proposed temporary reduction of the required number of operable snubbers for the purpose of performing necessary plant improvements is acceptable.
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 Section 8002150 M 51.5(d)(4) that an environmental impact statement, or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of these amendments.
Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the amendments do not involve a significant increase in the probability or con-sequences 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 amendments will not be inimical to the common defense and security or to the health and safety of the public.
Dated:
February 1, 1980
.