Shielding Analysis Of The Unit Of Lead-Bismuth Cooled Reactor With Monte Carlo Method

Accelerator Driven Sub-critical System is a new type of nuclear device, and it is recognized as the most efficient nuclear waste transmutation technology. With the support of Chinese Academy of Science Strategic Priority Research, FDS Team conducts comprehensive design and research of Lead-Bismuth Cooled Reactor, and has carried out the preliminary conceptual design of a reference reactor, including preliminary shielding design. To evaluate if the reference reactor preliminary shielding design meets the guidelines and requirements for reactor shielding design, this thesis conducts radiation shielding calculation and optimization study of the unit of the reference reactor with high accuracy Monte Carlo methods.This thesis conducts radiation shielding calculation on the unit of the reference reactor, primary works are:firstly, based on the spallation sources obtained by FLUKA simulation, the radiation shielding calculation was performed with Super Monte Carlo Simulation Program for Nuclear and Radiation Process (SuperMC), and the calculation contained:neutron flux of the key components, fast neutron flux rate of the reactor vessel, neutron and photon energy flux of the inner surface of the biological shielding around the reactor, and dose rate and thermal neutron flux of the outer surface of the biological shielding around the reactor. Then, with the neutron flux of irreplaceable components, the maximum DPA was also calculated with SPECTER. Finally, according to the physical parameters in the shielding calculation, the rationality of the preliminary shielding design was confirmed. Meanwhile, to validate the correctness of the calculation, SuperMC calculation results of fast neutron flux rate of the safety vessel were compared with those of international MC code MCNP, and the maximum deviation of the results are0.16%, which are coincided with each other. The results of the shielding calculation not only confirm that the radiation dose of the components of the reactor meet shielding design requirements, but also guarantee that the radiation dose don’t exceed the occupation limitation, which assure the radiation safety for operators.In addition, based on the properties of the radiation particles penetrating reactor flank and the attenuation pattern of neutron in different shielding materials, the layout of the shield is optimized from the perspective of safety. Finally, a more conservative shielding design is proposed to guarantee radiation safety furtherly, whose outer surface dose rate of the biological shielding is six time lower than that of preliminary shielding design. And the optimization can be a reference for actual design.