Document: NUREG-0800
Document ID: 8da52d2b-9980-4076-8056-2cafebb25ed6
Document Type: srp
Title: THERMAL AND HYDRAULIC DESIGN
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550060.pdf
Revision Date: 2023-06
Chapter: 4
Section ID: 4.4
CFR Part: 
CFR Title: 

Content:
a manner that accounts for all possible reactor operating states as determined from operating maps. In this regard, the reviewer confirms that the power distribution assumptions of SAR or DCD Section 4.4 are a conservative (i.e., worst-case) accounting of the power distributions derived in SAR or DCD Section 4.3 from core physics analyses and that the latter analyses include an acceptable calculation of local void fractions. The reviewer also confirms that the mass flux used in these calculations accounts for the core flow distribution (including that for partial loop operation and natural circulation effects in the case of ESBWR) and the worst case of core bypass flow. The reviewer confirms that startup measurements will verify the primary coolant flow range shown in the operating map. 9. The applicable reviewer considers the design review areas of applicability associated with ATWS and thermal-hydraulic instability using the guidance found in the requirements of SRP Sections 15.8 and 15.9. 4.4-10 Revision 2 - March 2007 10. For PWR and BWR applicants proposing operation with one of the reactor coolant pumps out of operation (i.e., (N-1) loop operation), the reviewer determines the acceptability of such a mode of operation based on the applicant’s safety analyses and proposed technical specifications (Generic Letter No. 82-28). Plant-specific aspects of the safety analyses may identify safety questions which could affect decisions regarding the desirability of (N-1) loop operation. Considerations related to reactor thermal- hydraulics include effects on core flow and temperature distributions and the ability of instrumentation to accurately reflect in-core parameters related to specified limits of DNBR or MCHFR. When performing review of thermal-hydraulics instabilities resulting from (N-1) loop and other operational circumstances, the reviewer should use the guidance found in the requirements of SRP Section 15.9. The reviewer should also verify that the