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:
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 different plants and/or fuel types. Typical values are 1.06 and 1.07. b. PWRs - The value of the minimum DNBR calculated with due allowance for mixing grids (Refs. 3, 4, and 5) is typically 1.30 using the BAW-2 correlation (Ref. 6) or the W-3 correlation (Ref. 7). Much lower values, depending upon the test data base and fuel design, are acceptable for more recent correlations such as the WRB-1, CE-i, and BWC. 2. Problems affecting DNBR or CPR limits, such as fuel densification or rod bowing, are accounted for by an appropriate design penalty which is determined experimentally or analytically. Subchannel hydraulic analysis codes such as those described in References 8 and 9, should be used to calculate local fluid conditions within fuel assemblies for use in PWR DNB correlations. The acceptability of such codes must be demonstrated by measurements made in large lattice experiments or power reactor cores. The effects of radial pressure gradients in the core flow distribution should be evaluated. Calculations of BWR fluid conditions for use in CHF correlations have been in accordance with the models specified in Reference 10 and 11. 3. The reactor should be demonstrated to have sufficient margin to be free of undamped oscillations and other thermal-hydraulic instabilities for all conditions of steady-state operation (including part loop operation), and for anticipated operational occurrences. 4. Methods for calculating single-phase and two-phase fluid flow in the reactor vessel and other components should include classical fluid mechanics relationships and appropriate empirical correlations. For components of unusual geometry, such as the following, these relationships should be confirmed empirically, using representative data bases from approved reports of the type