Study On Core Layout Schemes And Control Methods Of A Lead Cooled Fast Reactor Based On Thorium And Plutonium Mixed Fuel

In the context of the global shortage of uranium raw materials,countries are actively looking for alternative fuels,as a kind of alternative nuclear fuel,the fission material ²³³U produced by thorium after absorbing neutrons has a high conversion ratio in the middle and high energy region,at the same time,the potential reserves of thorium resources in China have been in the forefront of the world;the paper reference LFR at home and abroad,with flattened core neutron flux and power for the design target,the core charging scheme of T-PLFR（Th-Pu Lead-Cooled Fast Reactor）was designed and calculated by Monte Carlo software,and the control rod design and optimization were carried out.The work content of this paper is as follows:（1）Referring to the relevant literature at home and abroad,the layout of T-PLFR core assembly is investigated,the specific parameters of core fuel assembly,control assembly and reflector assembly are determined,and the whole reactor physical model is established by using Monte Carlo program.（2）The non-uniform core is adopted in the arrangement design of the core fuel assembly,and the content of the fissionable nuclides in the fuel assembly is analyzed and determined.On the basis of not changing the number of fuel assemblies,a variety of arrangement schemes of the core fuel assembly are tested from two aspects of regional zoning and discrete arrangement,named a（internal and external partition type）,B（alternate Division District type）,C（distributed layout type）and D（discrete layout type）scheme.（3）Four kinds of in core fuel assembly layout schemes are simulated and calculated,and the data are processed by MATLAB to plot.The neutron flux and fission energy deposition distribution are analyzed from the radial and axial direction of the core,and the optimal in core fuel assembly layout scheme of T-PLFR is determined,and the burnup calculation is carried out on this basis;Finally,by using different nuclear databases,the reliability of calculation results and the characteristics and differences between the databases are explored.（4）the boron carbide is chosen as the reactor control rod material,independent design,overall redundant safety systems and control rod system,the control rod assembly was optimized based on the final core layout,and verification card stick criteria accord with the experiment,explore the control rod system insert core the influence of different depth of core axial parameters.The results show that the neutron flux density level of the fuel assembly is 15 orders of magnitude when the core of the lead cooled fast reactor is critical;Scheme B（alternate zone type）with the most uniform distribution of physical parameters is determined as the final core fuel arrangement of T-PLFR.The burnup calculation results show that thorium based fuel has certain advantages in reducing Ma and has strong conversion ability;The optimized safety rod system meets the rod sticking criterion,and both the safety rod system and the control rod system can be effectively shut down to meet the design requirements;It is found that when the control rod is raised to 40%to 60%of the core height,the introduction reactivity is the most severe,the axial power and the neutron flux nonuniformity coefficient first increase and then gradually decrease,and reach the peak when the control rod is in the middle of the core;In this paper,the Monte Carlo transport calculation program is used to do a lot of calculation and analysis to verify the feasibility of T-PLFR concept.