Spatially dependent self-shielding method with temperature distribution for LWR lattice physics code PARAGON

The power distribution within the fuel rod is usually needed in fuel integrity evaluation. To compute the radial power distribution, a multi-ring flux solver, a space dependent resonance self-shielding module and a multi-ring depletion module are required. Conventional LWR design codes have almost all of the functions except for the space dependent resonance shielding. Therefore, we had developed SDDM (Spatially Dependent Dancoff Method) and validated the method with Monte Carlo calculations and PIE data. However, the evaluation with the SDDM lacked the temperature distribution within fuel rods. In this paper, the new development of the SDDM with temperature distribution is presented. The preliminary study for the SDDM with temperature distribution was previously discussed in reference [3]. Then it was found that the SDDM predicts a much larger reactivity effect due to the temperature distribution than MCNP. Here, the improvement to the SDDM corrects this overprediction and it will be supported by numerical results. (authors)