Document: NUREG-0800
Document ID: 3ea2f0ac-4d7e-464a-b1c4-390c3970f642
Document Type: srp
Title: provides specific thermal-hydraulic criteria.  The available radioactive fission product
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0707/ML070740002.pdf
Revision Date: 2023-06
Chapter: 4
Section ID: 4.4
CFR Part: 
CFR Title: 

Content:
is appendix. The second criterion must be satisfied for SSE loads alone if Subsection IV.1 does not require an analysis for combined loads. 4.2-33 Revision 3 - March 2007 APPENDIX B INTERIM ACCEPTANCE CRITERIA AND GUIDANCE FOR THE REACTIVITY INITIATED ACCIDENTS A. BACKGROUND This appendix provides the interim acceptance criteria and guidance for the reactivity-initiated accident (RIA). RIAs consist of postulated accidents which involve a sudden and rapid insertion of positive reactivity. These accident scenarios include a control rod ejection (CRE) for pressurized water reactors (PWRs) and a control rod drop accident (CRDA) for boiling water reactors (BWRs). The uncontrolled movement of a single control rod out of the core results in a positive reactivity insertion which promptly increases local core power. Fuel temperatures rapidly increase, prompting fuel pellet thermal expansion. The reactivity excursion is initially mitigated by Doppler feedback and delayed neutron effects followed by reactor trip. Standard Review Plan (SRP) Section 15.4.8 and 15.4.9 provide further detail on the CRE and CRDA respectively. The technical and regulatory basis of this interim criteria is documented in a memorandum dated January 19, 2007 (ADAMS ML070220400). B. FUEL CLADDING FAILURE CRITERIA The total number of fuel rods that must be considered in the radiological assessment is equal to the sum of all of the fuel rods failing each of the criteria below. Applicants do not need to double count fuel rods that are predicted to fail more than one of the criteria. 1. The high cladding temperature failure criteria for zero power conditions is a peak radial average fuel enthalpy greater than 170 cal/g for fuel rods with an internal rod pressure at or below system pressure and 150 cal/g for fuel rods with an internal rod pressure exceeding system pressure. For intermediate (greater than 5% rated thermal power) and full power conditions, fuel cladding failure is presumed if local heat flux