This work aims to improve the coupled calculations required for the modeling of nuclear reactors by producing more advanced computational tools.

The study applies more advanced computational tools to more detailed modeling of the random structure in pebble bed reactors and temperature distributions formed in the fuel rods of light water reactors. As part of the calculation applied to light water reactors, a coupling code is created that links the reactor physics code utilizing the Monte Carlo method and the traditional fuel code to the coupled calculation.

The calculations performed in pebble bed and light water reactors show that the Monte Carlo reactor physics code can be used as part of a calculation system that produces accurate comparison results or solves specific challenging problems where increased use of calculation capacity is justified. The comparison results calculated by such a coupling can be utilized in the future to improve the accuracy of simpler and faster calculation codes.