Transient CFD/Monte-Carlo Neutron Transport Coupling Scheme for simulation of a control rod extraction in TRIGA reactor

The computational model of the JSI TRIGA Mark II, coupling Monte-Carlo neutron transport code TRIPOLI and computational fluid dynamics code CFX was used to reproduce the behaviour of the reactor after extraction of a control rod. To tackle the time dependent Boltzmann equation, a quasistatic approach has been used and compared with point kinetic. Qualitative assessment of the model was performed by comparison with measured fuel temperature and power. Time evolutions of power and fuel temperature were reproduced. The quasistatic approximation was justified by updating the shape function at different time intervals. The quasistatic approach successfully reproduces the experimental results obtained with the TRIGA reactor. It was shown that most of the local effects (temperature, power density) were due to the control rod and that local effects of coupling were small.