A new treatment for neutron scattering with heavy nuclei was recently implemented in the Monte Carlo neutron/photon transport code MCNP. This treatment replaces the former approximation procedure which for the resonances neglects the energy and angular distribution of the scattered neutrons. Preliminary calculations already showed that the impact of this new treatment on the Doppler reactivity effect of Light Water Reactors (LWR) ranges from 8 to 16 % assuming an average fuel temperature. A precise assessment of the Doppler reactivity effect, however, is of essential importance for the nuclear reactor safety.
The objective of this work is to quantify the impact of the new scattering method on LWR unit cell calculations. A detailed model of a fuel pin is used to describe the radial and axial fuel temperature distribution. In the first part of the work the Doppler reactivity effect is determined for Uranium Oxide (UOX) and Mixed Uranium/Plutonium Oxide (MOX) fuel pins. In the second part, burn-up calculations are performed and the influence on the fuel inventory is investigated.
This work permits to the student to gain detailed insight into a state-of-the-art reactor physics computational tool, to obtain important reactor physics knowledge and work in an international research group.
