[en] The author's experience in the analysis thermal method application at WWR-M of the Ukrainian Academy of Science and in ''hot'' laboratory in the course of polymeric and metal material stability investigation is reflected. Disastrous radiation effects in materials irradiated by fast neutrons under increased dose rates qv=0,5-15 Wt/g, exposure doses E_n=1-10 - 100-1000 Mrad and fast neutron fluences from 10¹⁸ to 10²¹ n/cm² were investigated. Disastrous phenomena may occure in the following cases: a) in modern silicon-organic coolants (complete fluid fluidity loss at E_n of about 200 Mrad); b) at paradoxially reverse relationship of electric break-down strength of technically important insulators (due to thermal breakdown at the reactor radiation absorbed energy qv from 0,5 to 20 Wt/g); c) during ''Wigner disaster'' for metallic material state (i.e. under thernal-activated discharge of radiation defect excessive energy at fcc, hcp and bcc crystallography within the range of 300-700 K). Thermal-electric effects in neutron irradiated metals and alloys are investigated as an additional way to control thermokinetics and thermography of radioactive samples in physical metallurgy