MAXIMAL APPARENT TEMPERATURE AND TIME OF NONISOTHERMAL ANNEALING OF FUEL-PARTICLES DURING THE CHERNOBYL ACCIDENT

Basing on the fractionation factors of Cs-137 and Sr-90 in Chernobyl f uel particles, as well as on their burnups and the experimentally dete rmined temperature dependence of the apparent coefficients of the radi onuclide diffusion in UO2, the apparent time and maximal temperature o f nonisothermal annealing of the fuel particles during the accident ar e estimated. For nonisothermal (explosion) conditions, apparent maximu m temperatures of annealing of the fuel particles (> 20 mu m in size) during the explosion (median values T = 2630 and T = 2640 K, respectiv ely), temperature distributions, and the annealing times (median value s t = 17 s and t = 27 s, respectively) are estimated for the cases of the linear and exponential temperature rise. Basing on the burnups of the fuel particles released from the reactor during the explosion, elu cidation of the area in the reactor core from which the particles had been released is attempted.