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:
s in accordance with the recommendations of topical reports NEDO-31960 and NEDO-31960 Supplement 1 as approved by the related NRC SER (Reference 15).58 2. Thermal-hydraulic behavior during ATWS events has been analyzed as discussed in specific acceptance criterion II.10. Procedures direct appropriate actions to suppress thermal-hydraulic instability-related power oscillations during an ATWS event, similar to the actions discussed in Reference 16.59 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 whether such a mode of operation is acceptable based on the applicant's safety analyses and proposed technical specifications (Reference 11). Plant specific aspects of the safety analyses, may identify safety questions that 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. For BWR applicants, the reviewer should verify that N-1 loop operation will not result in thermal-hydraulic instabilities associated with the corresponding reduction in RCS flow, or that adequate procedures, including supporting analyses and associated technical specifications exist to respond to potential instabilities. The reviewer should also verify that the possibility for jet pump vibration during N-1 operation has been addressed by the applicant. For ABWR applicants proposing to operate with less than the maximum number of 10 Reactor Internal Pumps (RIPs), the reviewer confirms that with fewer than 10 RIPs in operation, continued plant operation including any reactor power level restrictions, are compatible with the plant safety analyses, and flow test results demonstrate there are no significant differences in core flow patterns.60 The