ML20235M908
| ML20235M908 | |
| Person / Time | |
|---|---|
| Issue date: | 05/08/1969 |
| From: | Hanauer S Advisory Committee on Reactor Safeguards |
| To: | Griffiths T UNITED KINGDOM |
| Shared Package | |
| ML20235M427 | List:
|
| References | |
| FOIA-87-40 ACRS-GENERAL, NUDOCS 8707170372 | |
| Download: ML20235M908 (2) | |
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ADVISORY COMMITTEE ON REACTOR SAFEGUARDS UNITED STATES ATOMIC ENERGY COMMISSION WASHINGTON, D.C. 20545 i Way 8. 1969 Mr. Trevor Griffiths Ministry of Power Thames Mouse South !
Millbank, London. 8.W.1 England
Dear Mr. Griffiths:
Enclosed you will find at last wy statenest to go with ths,B BS l meeting report from 28 March. I owe yes many apelegies for the late date you are receiving this paperg I was ill for several weeks. and very pressed afterward.
l It is a pleasure to thank you again for the hospitality sheva I sy wife and me while we were in London, and to express my colleagues' and my appreciation of the very salightening freak dimesssions, held.
I believe, to our mutual benefit. We leek forward to future sentime-ance of this association.
Sincerely.
~
Or1ginal Si Soed bF s.a. amanner y Stephen E. Raaseer h immen Attachment Stateneet lay S . B. Remove r ec w/steh: 1. F. Fraley 8707170372 870713 PDR FOIA THOMABB7-40 PllR 4
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ADVISORY COMMITTEE ON REACTOR SAFEGUARDS UNITED STATES ATOMIC ENERGY COMMISSION WASHINGTON, D.C. 20545 i
BTAT WINY BY 8. E. E&M&Fti The siting problem in the Waited States is evidently quite different from that in the Datted Kingdom at the present time. In the Waited States.
we do~ not now have the same urgemey to use the mere erban sites.
Nevertheless.
some of our problaes are the same en both sides of the Atlantie, se I will accede to the Chairman's wishes and make a few infosaal rescata.
Siting policy in the United States is set forth in Part 100 of Title 10 Code of Federal Regulations. Bere are defined the cotespts of esslasies area.
Icw population some, population caeter distance; here are gives referesse dose values accidents.
bility to be used in the evaluation of reactor sites w3xh respect to low probe-Consequence-limiting engineered safety features are used to reduce to allowable levels the doses from hypothesized mecidents.
The Chaitinan has asked me to seeseent particularly on the role of Probabil-ity enslysis in reactor safety evaluation to the United States. I must asy ti.at you are far ahead of us in the development sad application of these techniques. I believe that such endeavors obow great potential as a useful tool in making safety decisions and I hope they are coatissed both here med at home.
We are not ready is the United States to accept probabilistic analy- }
sis as the sole basis for the judgement of acceptability of a remeter er a site. !
The reason Low-probability for this is that safety revier dents in part with very severe.
accidents.
Probabilistic study of such occidents is ancessarily heed on experience with much less severe seeidents of each higher treguency of accurrence. '
It is not presently known whether extrapolation from less severe accideets to the most severe postulated accidents correspeeds te reality.
Furthermore, available accident dets are based on the less severe recurrences and will not in the foreseeable future, we hope, be estended to give realistic values for probability of the very severe accidents.
Our experience is that accidents eccur in unexpected weys. We maste therefore, he vigilaat in searching for all accident modeep to the estaat that probability analysis helps us in this, it is to be encouraged. Bowever, in my opinion, es have not yet arrived at the point d ere probability analysis tech-mLques give adequate assurance that all failure modes are ladeed considered, thet the probshilistic model for savare accidents corresponds to the metaal failures that will occur, and that adequate failure rate dets are svettable for prediction. Batil these requirements for predictica are fulfilled.
probability smalysis will coatiaue to be saly one of several teshaiques need fie safety analysis.
e e e