Presented in the paper are the results of a parametrical study with the use of optimized modules of the FALCON code (FALCON-PSI) that addresses the effects of the selected characteristics of fast thermal transients (e.g., impulse width), fuel rod design (e.g., active fuel attack length) and boundary conditions (e.g., the coolant conditions) on fuel behaviour during a RIA. Specifically, the analysis of the governing processes for the fuel rod behaviour during the RIA events simulated in the experimental facility of the Nuclear Safety Research Reactor (NSRR, Japan) are in the focus of the present study. The results obtained can be useful for a better transfer of the NSRR test results in relation to the corresponding behaviour in LWRs and furthermore might also support the planning of future additional experiments.