Development and validation of the Serpent2 model of the BR1 reactor

This thesis focuses on the Belgian Reactor 1, which is an air cooled, graphite moderated reactor located at the Belgian Research Centre SCK CEN in Mol. The current BR1 model, to be used in Serpent2, is completed and cross-checked with original documents. A sensitivity analysis is performed, which made clear that factors such as the temperature, the use of thermal scattering libraries and different nuclear data libraries have a significant impact on the calculation of keff. It is determined that perturbations in the radiative capture cross-section of 238U and the fission cross-section of 235U can have an influence on keff by using the tool 'NDaST'. The possibility to decouple the thermal column from the full model is researched by characterising the neutron flow towards the column. Calculations in the column are compared with experimental results in the empty cavity and in two converter devices MARK III and the spherical shells. The spectrum in the empty cavity, in MARK III and in the spherical shells are as expected. The radial distribution in the empty cavity shows a divergence from experimental results. The axial distribution in the cavity and both the radial and axial distributions in MARK III are well fitted by calculations. Additional research of the radial and axial distribution in the spherical shells could further substantiate that the decoupling does not influence calculations in the cavity.