The Research Of Reactivity Control To Supercritical Water Cooled Fast Reactor

Supercritical water cooled fast reactor compared with supercritical water cooled thermal reactor, there is no need for independent moderator channels, the design of the fuel assembly is easier; the neutron energy spectrum is harder than thermal reactor, so it can not only produce power, but also has the potential of breeding nuclear fuel and transmuting MA. The negative void coefficient effect and the core breeding ratio of supercritical water cooled fast reactor has researched in china and abroad, but the research of reactivity control to supercritical water cooled fast reactor’s core design is necessarily. Because of its high outlet temperature and low density of the coolant, unable to add boric acid in the coolant for reactivity control, so there are only burnable poisons and the control rods can be used for excess reactivity and various reactive loss compensation of supercritical water cooled fast reactor.In this paper, a seed assembly model of supercritical water cooled fast reactor has been established by Dragon program, Calculated and analyzed the neutronics parameters of seed assembly with discrete type burnable poison and integral type burnable poison, it worked out that the integral type burnable poison can make the seed assembly having better distortion of power distribution, the reactive suppression in the begin of life and the residual absorption penalty in the end of life.The model of supercritical water cooled fast reactor has been established by MCNP which based on Monte Carlo method, calculated and analyzed the neutronics parameters of seed assembly with integral type burnable poison rare earth oxides Er2O3 and IFBA, it worked out that the mass fraction 1% of rare earth oxides Er2O3 dispersed on the seed assembly of all fuel rods can make core gets better reactivity control results.And further calculated and analyzed the neutronics parameters of SCFR-M with the Ag- In–Cd control rod and B4 C control rod, which core have had burnable poison. it worked out that the number of 6 seed assembly in the core which make B4 C as regulating rod can make the core on critical operation, power peak factor to 1.2504, and has the negative void coefficient effect, and the rich of 10 B is19.9%; the number of 39 seed assembly in the core, which B4 C as regulating shut down rod can make the core To arrive at the depth of the minimum shutdown, when inserted into the minimum number of shut down rod,ang the rich of 10 B is 90%. And this scheme can satisfy the card criterion.This issue provides basic reference for the physics reactor core design of the supercritical water cooled fast reactor, has great significance for the application and development of the supercritical water cooled fast reactor.