Published 8 issues per year
ISSN Print: 2150-3621
ISSN Online: 2150-363X
Indexed in
ENGINEERING APPROACH FOR THERMAL CALCULATIONS OF HEAT TRANSFER IN HEAT-RELEASED ROD BUNDLES COOLED BY NATURAL CONVECTION AND RADIATION
ABSTRACT
Transportation of spent fuel assemblies of nuclear power plants and special nuclear reactors is carried out in thick-walled canisters (casks). Such capacitances provide protection of personnel and the environment from ionizing radiation. The casks can be transported in vertical or horizontal orientation. Cooling of the cask must ensure removal of residual heat, maintaining an acceptable level of the temperature of the fuel assemblies during the long-term period. At the Polzunov Institute, the main principles of simplified thermal calculations of casks were developed and 13 experimental sections were investigated with three types of rod arrangements: hexahedral, round, and rectangular. Radiative-conductive and radiative-natural convective regimes are studied. On the basis of experimental and theoretical studies, algorithms and applied programs of thermal computation of canisters were developed. The thermal regime was also studied by performing full-scale experiments in operational conditions when the casks were loaded with real assemblies. The estimation of effective heat conduction was fulfilled in the axial direction while taking into account natural convection. The boundary for the start of convection in a geometrically complicated system and the interaction of different heat transfer mechanisms have been refined. Presented experimental results allow the understanding of a heat transfer mechanism in bundles of heat-generating rods. Several main regimes of heat transfer are described. Some unexpected effects that occur in these systems are also demonstrated. This method of approximate homogenization allowed us to avoid some difficulties related to thermal analysis and experimental data generalization.