ML20041B916
| ML20041B916 | |
| Person / Time | |
|---|---|
| Site: | 05000470 |
| Issue date: | 02/22/1982 |
| From: | Bernero R NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Eisenhut D, Hanauer S, Mattson R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML17297B299 | List: |
| References | |
| NUDOCS 8202250360 | |
| Download: ML20041B916 (3) | |
Text
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ATTACHMENT 4 UNITED STATES
[pa ate [o, NOCLEAR REGULATORY COMMisslON y'
.g-WASHINGTON, D. C. 20555 S
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January 22, 1982 y
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MEMORANDUM FOR:
9' Eisenhut, DL, NRR S. Hanauer, DST, NRR R. Mattson, DSI, NRR C. Michelson, AE0D T. Murley, ROGR l
H. Thompson, DHFS, NRR R. Vollmer, DE, NRR FROM:
Robert M. Bernero, Director Division of Risk Analysis Office of Nuclear Regulatory Research
SUBJECT:
ACCIDENT SEQUENCE PRECURSOR PROGRAM DRAFT MEPORT t
The attached Accident Sequence Precursor report is currently being edited}
by ORNL with expected publication in late March 1982.
We are providing a i
limited distribution of the draft report for information purpc:es.
The r
techniques and methodology used in the report are somewhat controversial.
For example, a question has been raised of whether the correct probabilities (absolute vs. conditional) were calculated and used to determine severe core melt probability. We are reviewing this and other methodology questions within DRA.
The Precursor Report tends to indicate a core melt probability J
higher than calculated in typicg/ reactor jear vs.10 g/ reactor / year for l PRAs.
The report i dicates core melt probability in the range of 10" e
typical PRAs. The precursor program tentative findings were presented by ORNL(JoeMinarek)toNRCinmeetingson9/18/81and12/9/81. Two earlier draft versions of this report were given limited distribution within NRC, the first in early 1981 and the second draft report was distributed following the 12/9/81 meeting.
We have indicated to ORNL that we will provide them l
timely comments before report publication.
Please provide us with any l
comments you may have on this report by February 20, 1982.
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P.obert M. Bernero, Director 8202250360 e2020s Division of Risk Analysis
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[DRADOCK05000 Office of Nuclear Regulatory Research
Attachment:
.As Stated cc:
R. Dennig, AE00 D. Okrent, ACRS D. Ross, RES L. Tong, RES A. Thadani, RRAB, NRR m
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DRAFT J
NUREG/CR-2497 Volume 1 ORNL/NSIC-182
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PRECURSORS TO POTENTIAL SEVERE CORE DAMAGE ACCIDENTS:
1969-1979 Joseph W. Minarick Casimir A. Kukielka i.
j Prepared for the U.S. Nuclear Regulatory Co= mission Office of Nuclear Regulatory Research Under Interagency Agreements. DOE 40-551-75 and 40-552-75 e
N NUCLEAR SAFETY INFORMATION CENTER NSIC 4
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ABSIEACT I
Descripticus of 170 operational events, reported as LERs, which. oc-curred at commercial light water reactor plants during 1969-1979 and which are considered to be potential precursors to severe core damage are pre-
's'ented, along with associated event trees and categorizations and subse-quant analyses. The report senmarizes work in (1) the development of methods used to screen about 19,400 LER abstracts for potential precur-l sors. (2) the initial screening of those abstracts to determine which should be reviewed in de tail, (3) the de tailed review of those selected LERs which then yielded the 370 events, (4). the ca tegoriza tion of the 170 events, (5)~ the calculation of function f ailure estimates based on precur-sor data, (6) the use of probability-of-severe core damage estimates to rank precursor events and the identification of $2 events considered sig-I nificant, (7) trends analyses of significant events, (8) the identifica-cion of the other events of interest which occurred within one month of significant events, and (9) calcula' tion of an estimate of severe core dam-age probability per reactor year based on the event rankings.
e 00E TO THE VOLUME OF THIS REPORT, ONLY THE ABSTRACT IS BEING SENT.
l THE BODY OF THE REPORT IS AVAILABLE UPON REQUEST.
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