ML030860496
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| ML030860496 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 06/04/2002 |
| From: | Long S Office of Nuclear Reactor Regulation |
| To: | |
| References | |
| FOIA/PA-2003-0018 | |
| Download: ML030860496 (3) | |
Text
File from Steve Long's computer dated 06/04/02 06:00am named "ACRS slides for risk consid.wpd" Risk Considerations ACDF will be more significant than ALERF because containment is not affected.
ACDF = AFrequency x CCDP CCDP for medium LOCA is known from available PRAs 3 x 10-' for Davis-Besse AFrequency still must be determined
AMLOCA Frequency Two components:
"* Frequency of RCS pressure transients reaching failure pressure of as-found cavity.
"* Probability that cavity would not have been discovered before cavity grew to size that would rupture at RCS normal operating pressure.
Both components require quantification of failure pressures Second component also requires quantification of growth rate.
SDP Lessons
- 1. This is an example of cases where not enough is known about the phenomenon to produce a risk estimate within the time-frame envisioned by the new ROP SDP.
- 2. SDP is risk-based. Other safety concepts of a risk-informed process seem to be driving the agency's regulatory response in the absence of a ACDF value. In this case, loss of design margin appears to be the most important principle for consideration.