Assessment of residual heat generation at cyclic operation of a research reactor as input data for thermal hydraulic calculations and safety analysis

The presented approach is applied to evaluate the residual heat generation in the reactor core in the reconstruction design of the nuclear research reactor IRT-2000, Sofia, Bulgaria, configured with LEU fuel IRT-4M (19.75% U235). The residual heat generation is estimated for the reactor core as a whole at operating power of 1000 kW in the end of the last working day after 2 weeks of operation in the following mode: 12 h per day, 5 days per week (Monday-Friday). The accumulated working and downtime hours during the operation period, as well as the weekend break, are accounted in the calculations.