Document: NUREG-0800
Document ID: e32f0820-4e33-476e-aa36-4ca8c2c64af0
Document Type: srp
Title: Use of Probabilistic Risk Assessment in Plant-Specific, Risk-Informed Decisionmaking:
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0119/ML011940192.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.0
CFR Part: 
CFR Title: 

Content:
with the guidelines for LERF. That is, both sets of guidelines should be satisfied. Specifically, the guidelines for LERF are as follows: If the application can clearly be shown to decrease LERF, the change is considered to satisfy the relevant principle of risk-informed regulation with respect to LERF. (Because Figure 1111-2 is drawn on a log scale, it does not explicitly indicate this region.) When the calculated increase in LERF is very small (less than 1 x 10' per reactor year), the change should be considered regardless of whether there is an assessment of total LERF (Region Ill). While there is no requirement for the licensee to quantitatively assess the total LERF, information should be provided to show that there is no indication that the total LERF could considerably exceed 1 x 10' per reactor year. Such an indication could result, for example, if the contribution to LERF calculated from a ýlimited scope analysis (such as that from the IPE or the IPEEE) significantly exceeds 1 x 10'5 per reactor year, if the licensee has identified a potential vulnerability from a margins-type analysis, or if plant operating experience has indicated a potential safety concern. When the calculated increase in LERF is in the range of 1 x 10`7 to 1 x 10-6 per reactor year, applications should be considered only if the licensee can reasonably show that the total LERF is less than 1 x 10' per reactor year (Region II). Applications which increase LERF by more than 1 x 10'6 per reactor year (Region I) should not normally be considered. These guidelines are intended to provide assurance that proposed increases in CDF and LERF are small and are consistent with the intent of the Commission's Safety Goal Policy Statement. The guidelines discussed above are applicable for full-power, low-power, and shutdown operations. However, during certain shutdown operations when the containment function is not maintained, the LERF guidelines as defined above are not practical. In such cases, the