Document: NUREG-0800
Document ID: 145ec0f9-012b-4669-9627-ed1b1d0cce95
Document Type: srp
Title: THERMAL AND HYDRAULIC DESIGN
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070412.pdf
Revision Date: 2023-06
Chapter: 4
Section ID: 4.4
CFR Part: 
CFR Title: 

Content:
culate local fluid conditions within fuel assemblies 33 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 References 1025 and 1126. 34 35 3. The design should address core oscillations and thermal hydraulic instabilities as follows: a. The reactor core and associated systems should be demonstrateddesigned 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 extended cycle operation with reduced feedwater temperature, where these operating conditions are proposed) , and for anticipated operational 36 occurrences. b. If the possibility of oscillations cannot be eliminated, the capability shall exist to reliably and readily detect and suppress the oscillations should they occur. 37 Methodologies for resolving BWR core stability issues are presented in GE topical report NEDO-31960 along with its Supplement (References 29 and 30) and were approved by the NRC in Reference 15. These reports provide long-term solutions to BWR stability issues as well as methodologies that have been developed to support the design of systems needed to ensure that plants are in compliance with GDC 10 and 12.38 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 listed below. a. Reactor vessel (Ref. 12Reference 27) . 39 DRAFT