Document: NUREG-0800
Document ID: 855b2438-2ddf-48e9-8762-e39097109e12
Document Type: srp
Title: FUEL SYSTEM DESIGN
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340660.pdf
Revision Date: 2023-06
Chapter: 4
Section ID: 4.2
CFR Part: 
CFR Title: 

Content:
e design bases and related parameters can only be evaluated with calculational procedures. The analytical methods that are used to make performance predictions must be reviewed. Many such reviews have been performed establishing numerous examples for the reviewer. The following paragraphs discuss the more established review patterns and provide many related references. (a) Fuel Temperatures (Stored'Energy): Fuel temperatures and stored energy during normal operation are needed as input to ECCS performance calculations. The temperature calculations require complex computer codes that model many different phenomena. Phenomenological models that should be reviewed include the following: Radial power distribution Fuel and cladding temperature distribution Burnup distribution in the fuel Thermal conductivity of the fuel, cladding, cladding crud, and oxidation layers Densification of the fuel Thermal expansion of the fuel and cladding Fission gas production and release Solid and gaseous fission product swelling Fuel restructuring and relocation Fuel and cladding dimensional changes Fuel-to-cladding heat transfer coefficient Thermal conductivity of the gas mixture Thermal conductivity in the Knudsen domain Fuel-to-cladding contact pressure Heat capacity of the fuel and cladding Growth and creep of the cladding Rod internal gas pressure and composition Sorption of helium and other fill gases Cladding oxide and crud layer thickness Cladding-to-coolant heat transfer coefficient* Because of the strong interaction between these models, overall code behavior must be checked against data (standard problems or benchmarks) and the NRC audit codes (Refs. 14 and 15). Examples of previous fuel performance code reviews are given in References 16 through 20. (b) Densification Effects: In addition to its effect on fuel temperatures (discussed above), densification affects (1) core Although needed in fuel performance codes, this model is reviewed as described in SRP Section 4.4. 4.2-10