Determining temperature distributions inside a nuclear reactor

摘要

In a nuclear reactor, energetic particles are generated in the fuel region during the fission process. As these particles are slowed down and absorbed by material in the reactor, this material is heated. The material is cooled by convection of hydrogen flowing through coolant channels. The primary contributions to this heating process are neutrons and gamma rays. The neutrons have a short mean free-path. They travel a relatively short distance between collisions with nuclei of surrounding material and most end up being absorbed within the fuel region which is about 1 cm thick. Gamma rays, on the other hand, travel a comparatively longer distance between collisions and they travel tens of centimeters from their point of creation. We are interested in the temperature distribution of moderating material, therefore, the primary source of heating will be gamma rays. Modeling the entire reactor for computer simulation would be rather expensive and time consuming (both personnel time and machine time). Consequently, this report utilizes a two dimensional description of the ''worst case.'' The ''worst case'' is one in which the heating rate is highest and the cooling rate is lowest. The computer simulation is, therefore, a two dimensional model which is heated by radiation and cooled by convection.