ML20056F291
| ML20056F291 | |
| Person / Time | |
|---|---|
| Issue date: | 05/22/1993 |
| From: | Thadani A Office of Nuclear Reactor Regulation |
| To: | Royen J ORGANIZATION FOR ECONOMIC COOPERATION & DEVELOPMENT |
| References | |
| NUDOCS 9308260315 | |
| Download: ML20056F291 (3) | |
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May 22, 1993 Mr. Jacques Royen, Deputy Head Nuclear Safety Division OECD Nuclear Energy Agency Le Seine St-Germain 12, Boulevard des Iles 92130 Issy-les-Moulineaux France
Dear Mr. Royen:
Thank you for your letter of May 14, 1993, and your excellent comments.
We both agree that containment performance should remain a focal point of the meeting.
I also agree, however, that the relevant in-vessel topics, as well j
as appropriate accident management elements should be included in the meeting i
agenda. Selected issues like core debris composition, bottom head failure mode, and accident mitigation capabilities have a direct impact on containment performance. Also, I believe, the regulatory approach to the containment performance should be consistent with our understanding of relevant in-vessel issues and mitigation strategy.
I have reviewed our broad outline of the meeting agenda and I agree with your suggestions.
In fact, the in-vessel topics should fit well within the l
DOMINANT SEVERE ACCIDENT CHALLENGES, and the accident management issues could be included in the MITIGATION STRATEGIES. Our suggestions are included in the j
attached enclosure.
My staff and I look forward to discussing with you any further details of the proposed meeting. Again, feel free to contact Mr. Kudrick directly at (301) 504-2871.
Sincerely, Originals!gnedby A.C.Thadani Ashok C. Thadani, Director Division of Systems Safety and Analysis Office of Nuclear Reactor Regulation
Enclosure:
As stated l
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l ENCLOSURE TOPICS FOR CNRA MEETING ON
" CLOSURE OF SEVERE ACCIDENTS FOR EVOLUTIONARY REACTORS" i
i G0ALS/0BJECTIVES What level of performance for severe accidents is expected for containments?
How can we account for existing uncertainties?
REGULATORY APPROACH What regulatory approach is taken to achieve goals / objectives for containment performance?-
DOMINANT SEVERE ACCIDENT CHALLENGES State of knowledge of the leading severe accident phenomena.
Develop consensus on the range of relevant parameters, like:
degree of core melt amount of generated hydrogen local-to-average hydrogen concentration i
bottom-head failure mode and rate of core debris injection core debris coolability MITIGATION STRATEGIES Discuss the state of knowledge of hardware and procedures to delay, mitigate, or prevent the release of radionucludes, including:
what are criteria to declare the SEVERE ACCIDENT status?
do normal operation control panels provide sufficient information for the accident management decisions?
can we develop guidelines for an operator to " expect the unexpected?"
under what circumstances should water addition into the system be discouraged?
when and/or-if containment venting should be recommended?
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2 ANALYSIS METHOD Discuss the status of knowledge of analytical techniques and codes for severe accident analysis, including analytical models for the in-vessel and ex-vessel phases.
CASE STUDIES Discussion of specific evolutionary reactor evaluations, including design, challenges, mitigation strategies, analysis results, and regulatory positions.
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