| The pebble bed reactor(PBR)is a kind of safe and advanced nuclear energy system,which can provide electric power and high temperature process heat efficiently and has the advantage of continuous fuel load.The accurate physics simulation of the pebble bed reactor is important and valuable,but it is difficult because the geometry of the pebble bed reactor is very complicated and not easy to be modeled with the traditional deterministic method.In this paper,the Monte Carlo method with strong ability of geometry description is adopted and the research on detailed model of pebble bed reactor is performed.Firstly,Monte Carlo method and code for neutron transport and the characteristics of pebble bed reactor are investigated comprehensively,which is the foundation of building the Monte Carlo model of the pebble bed reactor.And then the high-temperature gas-cooled reactor-pebble-bed module(HTR-PM)under construction in China is chosen to be researched.The detailed model of HTR-PM is built with Monte Carlo code,including the fuel sphere with TRISO fuel particles.the pebble bed containing fuel spheres and graphite spheres,the top cone and bottom cone in the core,channels of helium,control rods and absorber balls in the side reflector,and BaC rods in the bottom reflector.Also,the responding homogeneous models or equivalent models for convenient simulation are built and compared with the detailed models.The calculation results show that the Keff difference of detailed model and homogeneous model of the reflector region is small,even to be ignored,which means homogeneous model will not introduce obvious error.And the equivalent model 3 of the pebble bed region presents good computational accuracy for different quantity ratio of fuel spheres to graphite spheres in HTR-PM initial core.which means it can be recommended for the convenient simulation of pebble bed.The calculation results and analysis conclusions will benefit the design and operation work of pebble bed reactor. |
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