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:
ral Deformation. Appendix A discusses the acceptance criteria. vi. Rupture and Flow Blockage (Ballooning). The ECCS evaluation model includes Zircaloy rupture and flow blockage models, which should be reviewed by the organization responsible for reactor systems. The models are empirical and should be compared with relevant data. NUREG-0630, NUREG/CR-1883, and the publication on Burst Criterion of Zircaloy Fuel Cladding in a LOCA, August 4-7, 1980, provide examples of such data and previous reviews. These models should account for the phase transformation in the cladding at high temperatures. vii. Fuel Rod Pressure. The thermal performance code for calculating temperatures discussed in item 3.C.i above should be used to calculate fuel rod pressures in conformance with the fuel damage criteria of item 1.A.vi in Subsection II. This calculation should account for uncertainties in the estimated rod powers, code models, and fuel rod fabrication. The reviewer should ensure that conservatisms that were incorporated for calculating temperatures do not introduce nonconservatisms with regard to fuel rod pressures. viii. Metal/Water Reaction Rate. To meet the requirements of 10 CFR 50.46(b) as it relates to the performance of the ECCS during accidents, the rate of energy release, hydrogen generation, and cladding oxidation resulting from the reaction of the Zircaloy cladding with steam should be calculated. Currently this can be calculated in two ways. RG 1.157 allows the use of a best-estimate model, provided its technical basis is demonstrated with appropriate data and analyses. Alternatively, Appendix K to 10 CFR Part 50 specifies that the rate of energy release, hydrogen generation, and cladding oxidation from the metal/water 4.2-18 Revision 3 - March 2007 reaction should be calculated using the Baker-Just equation (Argonne National Laboratory Report ANL-6548, May 1962). For non-LOCA applications, other correlations may be used if justified. These reaction rate models were