Computer simulation of post-accident unit at the Chernobylsk NPP

The problem statement concerning the evolution of the thermal regime of the post-accident unit of the Chernobyl NPP is presented and basic equations of the mathematical model are derived. Solvability conditions of equations describing the post-accident unit steady-state cooling regime are investigated. Critical values of heat release in the debris, which results in steady-state regime destruction, when being exceeded are calculated. Based on elasto-granular motion equations, dynamic regimes of mobile integrity ruptures in debris reminding bubbles in liquid, the so-called dry boiling, are investigated. The structure of solving equations, describing the steady-state regime of cooling the debris in case of laminated, fiber, granular and mixed covering structures and heat release sources is investigated using asymptotic methods. The absence of considerable temperature (entropy) changes in the cooling air flow at the distances of the order of inhomogeneity scales in the debris is proved. Results of numeric simulation of the debris cooling process in the reactor well by convective filtration heat flux, occuring under effect of buoyancy forces due to heating in the debris of the air coming through the reactor base, are presented