Monte Carlo fuel temperature reactivity coefficient calculations by adjoint-weighted correlated sampling method

It is very time-consuming to estimate the fuel temperature reactivity coefficient (FTC) with high accuracy based on the subtraction of two reactivity values calculated at different fuel temperatures by a Monte Carlo (MC) neutron transport analysis code. We present a new MC FTC estimation method based on the perturbation techniques. The effectiveness of the new method is examined through the continuous energy MC neutronics calculations for the CANDU lattice problem. It is shown that the proposed method can predict the reactivity change due to the fuel temperature variation efficiently. From its numerical results, the reaction-wise contributions to the FTC are investigated with different resonance scattering models – the free-monatomic-gas models with constant cross section and resonance cross section. (author)