Nonmonotonic Embrittlement of Vessel Steel

摘要

The possible reasons for the significant variance of the experimental data in the investigation of the influence of neutron irradiation on the properties of the vessel materials of nuclear reactors are analyzed. It is shown on the basis of our own experimental data and an analysis of foreign experimental data that the dependence of the degree of radiation embrittlement on the neutron fluence can be nonstandard (nonmonotonic). It is noted that the conventionally studied parameters, viz. the intensity of irradiation and the technological factor, can play only a secondary role when nonmonotonicity is taken into account. It is supposed that the defect structure resulting from neutron bombardment undergoes transformation once or periodically in the direction of loss or restoration of the initial properties. The defective material can be restored, specifically, at low dose of irradiation by corpuscular particles, i.e., at some point the degradation by irradiation in a certain dose range even acts as a healing factor.