Document: NUREG-0800
Document ID: 54e3d49d-900d-4fe8-9297-2fc04501e4e0
Document Type: srp
Title: THERMAL AND HYDRAULIC DESIGN
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340664.pdf
Revision Date: 2023-06
Chapter: 4
Section ID: 4.4
CFR Part: 
CFR Title: 

Content:
g normal operation or anticipated operational occurrences (AOO). Specific criteria necessary to meet the requirements of GDC 10 are as follows: 1. SRP Section 4.2 specifies the acceptance criteria for evaluation of fuel design limits. One of the criteria provides assurance that there be at least a 95% probability at a 95% confidence level that the hot fuel rod in the core does not experience a departure from nucleate boiling (DNB) or transition condition during normal operation or anticipated operational occurrence. Uncertainties in the values of process parameters, core design parameters, and calculational methods used in the assessment of thermal margin should be treated with at least a 95% probability at a 95% confidence level. 4.4-2 Rev. 1 - July 1981 Two examples of acceptable approaches to meet this criterion are: a. For departure from nucleate boiling ratio (DNBR), critical heat flux ratio (CHFR) or critical power ratio (CPR) correlations there should be a 95% probability at the 95% confidence level, that the hot rod in the core does not experience a departure from nucleate boiling or boiling transition condition during normal operation or anticipated operational occurrences; or b. For DNBR, CHFR or CPR correlations, the limiting (minimum) value of DNBR, CHFR, of CPR is to be established such that at least 99.9% of the fuel rods in the core would not be expected to experience depart- ure from nucleate boiling or boiling transition during normal operation or anticipated operational occurrences. Correlations of critical heat flux are continually being revised as a result of additional experimental data, changes in fuel assembly design, and improved calculational techniques involving coolant mixing and the effect of axial power distributions. As guidance to the reviewer, the correlations listed below have been found acceptable for previously reviewed plants. a. BWRs - The value of the minimum CPR calculated with the GETAB analysis (Ref. 2) will vary for