SPECIFIC FEATURES OF NUMERICAL SIMULATION OF THERMAL OPERATION MODE THE SPENT FUEL POOLS OF BILIBINO NPP

The paper considers methodological aspects during the development of thermo-hydro-dynamic of numerical calculation models for spent nuclear fuel pool (SNFP) on the example of Bilibino NPP by using international industry codes. The purpose of these models development is the fast simulation of thermal and humidity operational modes of spent fuel pool during periods of filling, "wet" and dry storage with an interval of up to 50 years, taking into account passive and forced convection heat removal systems. The following methodological aspects are considered in detail: 1. Use of isotope kinetics codes for calculating of the heat power dynamics for separate spent fuel assembly. 2. Calculation method of the heat removal power from the evaporation mirror of SNFP during “wet” storage, including evaporation power calculation and exhaust ventilation operation. Using the law of similarity of heat transfer and mass transfer processes (Lewis' law) for evaporation calculations. 3. Methods of accelerated computational forecasting of the dynamics of the thermal regimes of the SNFP during “wet” storage. 4. Condensation of atmospheric moisture at the bottom of the SNFP after “dry” storage and methods for its removal. It is shown that TRAC (TRACE) code with a 3D porous body model and complete evaporation-condensation models is the most suitable for solving the problems under consideration among the system thermo-hydraulic two-phase codes for nuclear energy.