Comparison of resonance elastic scattering models newly implemented in MVP continuous-energy Monte Carlo code

Mori, Takamasa; Nagaya, Yasunobu  

In order to investigate the impact of resonance elastic scattering models on the Doppler reactivity effect, the exact and the constant cross section models with the thermal motion of target nucleus were newly implemented into the MVP-2 continuous-energy Monte Carlo code with and without consideration of energy-dependent resonance cross section, respectively, and the UO pin-cell Doppler reactivity benchmark calculations were carried out with the modified code and the JENDL-3.3 library. The present study has revealed that the exact model gives more negative Doppler reactivity coefficients by 711% than the conventional asymptotic model, while the constant cross section model gives slightly less negative coefficients than the conventional asymptotic model. Furthermore, it is found that the impact of resonance elastic scattering models is considerably large around the resonances where elastic scattering has relatively high contribution, whereas capture-dominant resonances have no significant impacts on the Doppler reactivity coefficient.