Monochromator Shielding Design And Simulation

According to the demands of neutron scattering instrumentation, especially High Resolution Powder Diffractometer (HRPD) and High Intensity Powder Diffractometer (HIPD), to be built at China Advanced Research Reactor (CARR), the primary design of the shielding for HRPD and HIPD has been done. Moreover, the shielding effect is simulated using MCNP4C, a widely used Monte Carlo simulation code. The results of this thesis have provided essential data for the designs.HRPD and HIPD will be built at Thermal Neutron Double Beam Tube II .The simulation is divided into two steps. Firstly, according to the known data before the rotated doors, the shielding effect is calculated by Monte Carlo method when both of doors are closed. It is shown that the shielding is not enough, and it is necessary to add a 30cm-thick heavy concrete shielding wall with a density of 5.0g/cm~3. Secondly, the simulation result at the exit of rotation door which is opened, is used as source data to simulate the monochromator shielding. After simulating, the result shows that the primary design is enough to radiation safety protection, furthermore, the thickness of shielding can be reduced at some position. Finally, the optimized design for the shielding has been offered after thinking over the layout of CARR hall, the demands of instrumentation and the simulation results.To improve Monte Carlo sampling and solve deep penetration problem, multi-step method and geometry splitting with Russian roulette are used.