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
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Content:
design requirements of TMI Action Plan Item II.F.2 of NUREG-0737. Applicants subject to 10 CFR 50.34(f) should meet the requirements of 10 CFR 50.34(f)(2)(xviii). Procedures for detection and recovery from conditions of ICC must be consistent with technical guidelines, including applicable EPGs developed pursuant to the TMI action plan, that incorporate response predictions based on appropriate analyses. 10. Thermal-hydraulic stability performance of the core during an ATWS event should not exceed acceptable fuel design limits. SRP Sections 15.8 and 15.9 describe an acceptable method for performing such an analysis for BWR and PWR cores. Technical Rationale The technical rationale for application of these acceptance criteria to the areas of review addressed by this SRP section is discussed in the following paragraphs: 1. GDC 10 requires that the reactor core and associated coolant, control, and protection systems be designed with appropriate margin to assure that specified acceptable fuel design limits are not exceeded during any condition of normal operation, including the effects of AOOs. Proper thermal-hydraulic design of the reactor core and associated systems is necessary to assure that sufficient margin exists with regard to maintaining adequate heat transfer from the fuel to the RCS. Failure to maintain sufficient margin can result in a transition from nucleate boiling to film boiling on the fuel cladding surface. Film boiling decreases the heat transfer coefficient at the clad surface and the surface temperature rises significantly, eventually leading to fuel failure and the release of fission products to the RCS. Compliance with GDC 10 provides assurance that the integrity of the fuel and cladding will be maintained, thus preventing the potential for release of fission products during normal operation or AOOs. 2. GDC 12 requires that the reactor core and associated coolant, control, and protection systems be designed to assure that power oscillations that