ML20056D967
| ML20056D967 | |
| Person / Time | |
|---|---|
| Issue date: | 05/26/1993 |
| From: | Rogers K NRC COMMISSION (OCM) |
| To: | Chilk S NRC OFFICE OF THE SECRETARY (SECY) |
| References | |
| NUDOCS 9308190095 | |
| Download: ML20056D967 (3) | |
Text
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NOTATION V 0 T E ' _f[((gp3 fe, m
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RESPONSE SHEET
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SAMUEL J. CHILK, SECRETARY OF THE COMISSION FROM:
C0t44ISSIONER R0GERS
SUBJECT:
SECY-93-108 - REVISED GUIDELINES FOR PRIORITIZATION OF GENERIC SAFETY ISSUES ho eu APPROVED coJ2e~rs DISAPPROVED ABSTAIN net NOT PARTICIPATING REQUEST DISCUSSION 1
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Commissioner Rogers Comments on SECY-93-108 i
The proposed revised guidelines for the prioritization of generic safety issues (GSIs) should result in a process that is more
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closely aligned with the issue resolution process.
I agree with i
the raising of the risk thresholds by an order of magnitude and with the use of the impact /value ratio as opposed to the value/ impact ratio.
The latter will result in easier comparison to the $1000/ person-rem criterion used by the Commission.
I am concerned, however, with the specific implementation of the i
guidelines as reflected in the priority ranking grid in Figures 1 and 2 of NUREG-0933 (Enclosure 1).
While the priority ranking grid must, of necessity, have some i
arbitrary divisions, there should be some sort of logic in the priority selections.
The grid could be improved by adding some additional degree of symmetry and logic that would recognize the cost tradeoff possibilities in areas of intermediate risk.
For j
example (See Figure 1), in the region of change in core damage frequency (A CDF) between 10-5 and 10-4, there should be a tradeoff between HIGH and MEDIUM priority depending on the j
impact /value ratio.
If the cost is low enough (<1000/ person-rem), an issue should be pursued with a HIGH rather than MEDIUM priority.
B in the region of A CDF between and 10-5,y the same logic, 10-6 the cost tradeoff should result in a change from
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MEDIUM to LOW rather than from MEDIUM to DROP (i.e.,
if the relative cost was high (>1000/ person-rem) then the issue should-be given a LOW rather than a DROP priority).
These types of changes would add a symmetry and logic to the priority ranking grid.
The modified grid would look as follows-1 i
IMPACT /VALUE LEGEND.
$/ PERSON-REM PRIORITY
> 1,000 D
D L
M H
H = HIGH i
1,000 M = MEDIUM i
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< 1,000 D
L M
H H
L = LOW D = DROP i
10~7 10-6 10-5 10-4 I
A CDP per RY Using this modified grid, 2 of th^ HTGH and MEDIUM priority issues that were resolved with new.
uirements (Enclosure 2A) would be ranked in the new LOW category rather than in the DROP category (NEW PRIORITY column).
For the HIGH and MEDIUM priority issues resolved with no new requirements (Enclosure 2B), the ranking of 3 issues would be changed from MEDIUM to HIGH.and 12 l
issues would be changed from DROP to LOW.
The comparison of the distribution of HIGH, MEDIUM, LOW and DROP issues between the grid proposed by the staff and my suggested modified. grid are:
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=
w w
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2 e
HIGH MEDIUM LOW DROP Proposed 6
28 1
20 Modified 9
25 15 6
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While the modified grid does not change the HIGH-MEDIUM or LOW-DROP totals it does change the distributions to what appears to ne to be more reasonable.
The grid proposed by the staff would l
effectively eliminate the LOW category of. issues.
This significant reduction in the number of LOW priority issues will-seriously affect the usefulness of the periodic annual i
reassessment of low priority issues..This worthwhile annual review is performed only on LOW priority issues to see'if new information received during the past year warrants a revised i
priority ranking (An 11/6/87 SRM requested staff to conduct.these 3*
periodic reviews).
Accordingly, I suggest that the staff be asked to consider the use of the above modified priority ranking grid when ranking the GsIs.
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