Abstract
A new fuel performance modeling framework, CTFFuel, is developed from the subchannel code, CTF. The framework is a standalone interface to the CTF fuel rod models, allowing for fuel rod simulations to be run independently from the fluid. This paper provides an overview of the framework with application to the thermal conductivity degradation of LWR fuels. The modeling of fuel thermal conductivity degradation in the code is improved through the addition of new modeling options to account for the irradiation effects via globally defined parameters. After the initial implementation, a variety of order-of-accuracy tests and code comparisons are performed to test the software quality. A controlled analysis is allowed by CTFFuel to verify the numerical scheme of CTF's conduction solution and benchmark of the fuel thermal conductivity degradation again FRAPCON-4.0. Overall, the software quality and verification procedure ensure that the new model is coded correctly, that it properly interacts with the rest of the code, and that it can be used to predict thermal conductivity degradation for nuclear fuel rod behavior. The order-of-accuracy tests verified that the numerical scheme for CTF's conduction solution is coded correctly, and that the code converges to the exact solution. The code comparison showed that there is a significant improvement when the new thermal conductivity option is enabled, and CTF's credibility in prediction of thermal conductivity degradation is comparable with FRAPCON-4.0.
