Document: NUREG-0800
Document ID: 28c03fd2-3542-41ec-bfd7-5df2087c4ee6
Document Type: srp
Title: FUEL SYSTEM DESIGN
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070407.pdf
Revision Date: 2023-06
Chapter: 4
Section ID: 4.2
CFR Part: 
CFR Title: 

Content:
ing is given in Reference 2543 . Interim methods that may be used prior to 61 compliance with this guidance are given in Reference 2644 . At this 62 writing, the causes of fuel rod bowing are not well understood and mechanistic analyses of rod bowing are not being approved. (d) Structural Deformation: Acceptance Criteria are discussed in Appendix A, "Evaluation of Fuel Assembly Structural Response to Externally Applied Forces." (e) Rupture and Flow Blockage (Ballooning): Zircaloy rupture and flow blockage models are part of the ECCS evaluation model and should be reviewed by CPB SRXB . The models are empirical and should be 63 compared with relevant data. Examples of such data and previous reviews are contained in References 1022 , 1227 , and 1333 . 64 65 66 (f) Fuel Rod Pressure: The thermal performance code for calculating temperatures discussed in paragraph (a) above should be used to calculate fuel rod pressures in conformance with fuel damage criteria of Subsection II.A.1, paragraph (f). The reviewer should ensure that conservatisms that were incorporated for calculating temperatures do not introduce nonconservatisms with regard to fuel rod pressures. (g) Metal/Water Reaction Rate: To meet the requirements of 10 CFR 50.46 as it relates to the evaluation of 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. Regulatory Guide 1.157 allows the use of a best-estimate model provided its technical basis is demonstrated with appropriate data and analyses. Alternatively, Appendix K of 10 CFR 50.46 specifies thatTo meet the requirements of Appendix K of 10 CFR Part 50 (Ref. 9) as it relates to metal/water reaction rate, the rate of 67 energy release, hydrogen generation, and cladding oxidation from the metal/water reaction should be calculated using the Baker-Just equation (Reference. 2745). For non-LOCA applications,