The elastic-plastic cracking under the irradiation and cyclic loadings caused by thermo-acoustic instability of the heat-carrier in active zone

In conditions at which occurrence thermo-acoustic instability of heat-carrier (TAI) in an active zone of some reactors is possible, in particular for water-water reactors (WER installations of reactor) WER-1000 they are determined. In metal uranium thermal emission element's (TEE's) (both in the uranium core, and in a protective environment) thus there is an elastic - plastic development of cracks. In the generalized diagram of radiation-thermal creep of the metals, showing dependence of creep mechanisms on thermodynamic parameters such, as temperature, loading and neutron flux density is submitted. In it is shown, that in metal uranium at moderate temperatures and high neutron flux densities the radiation point defect concentrations considerably may exceed thermally equilibrium, also it is submitted the theoretical model of the established radiation creep within the framework of the mechanism of dislocation gliding and climbing, based on the conception of a dislocation as nonideal sink for point radiation defects. The similar phenomena it is necessary to expect and in a material of a protective environment which because of close contact to uranium also is exposed to intensive operation of division nucleus splinters of uranium. Computer modeling of radiation creep of metal uranium fuel has revealed its temperature nonlinearity. These temperature nonlinearities have served the reason for search of nonlinear effects and modes (in particular, concentration waves of point defects and their influence on radiating creep) in open nonlinear stochastic system which the system metal uranium fuel under an irradiation. As mechanisms of radiation-thermal plastic deformation in top of a crack, are identical to mechanisms of radiation-thermal creep the changes of mechanisms of radiation-thermal creep received in law on thermodynamic parameters may be the basis for development of the appropriate mechanisms of elastic - plastic development of cracks in metal uranium fuel. In the given work for WER installations of reactor with perspective metal uranium fuel are determined possible areas of thermodynamic parameters (temperature, loading and neutron flux densities) at which occurrence TAI, causes elastic - plastic development of cracks with possible course of plastic deformation on mechanisms to the similar mechanisms offered for radiation-thermal creep