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:
llooning: To meet the requirements of 10 CFR 50.46 as it relates to evaluating ECCS performance during accidents, burst strain and flow blockage caused by ballooning (swelling) of the cladding must be accounted for in the analysis of the core flow distribution. Regulatory Guide 1.157 describes models, correlations, data, and methods that are acceptable for meeting the requirements for a realistic calculation of ECCS performance during a LOCA. Alternatively, Appendix K to 10 CFR 50 presents acceptable features of a conservative evaluation model to consider burst strain and flow blockage.To meet the requirements of Appendix K of 10 CFR Part 50 as it relates to degree of swelling, burst strain and flow blockage resulting from cladding ballooning (swelling) must be taken into account in the analysis of core flow distribution. 46 Burst strain and flow blockage models must be based on applicable data (such as References. 1022, 1327, and 1233) in such a way that (1) the 47 temperature and differential pressure at which the cladding will rupture are properly estimated (see paragraph (h) of subsection II.A.2), (2) the resultant degree of cladding swelling is not underestimated, and (3) the associated reduction in assembly flow area is not underestimated. The flow blockage model evaluation is provided to the Reactor Systems Branch for incorporation in the comprehensive ECCS evaluation model to show that the 1204 C (2200 F) cladding temperature and 17% cladding 48 oxidation limits are not exceeded. The reviewer should also determine if fuel rod ballooning should be included in the analysis of other accidents involving system depressurization. (e) Structural Deformation: Analytical procedures are discussed in Appendix A, "Evaluation of Fuel Assembly Structural Response to Externally Applied Forces." B. Description and Design Drawings The reviewer should see that the fuel system description and design drawings are complete enough to provide an accurate representation and to