Experimental data for neutron spectrum influence on damage of reactor vessel material

Experimentally the differences in the change of embrittlement and strengthening of the 15Kh2MFA-A, 15Kh2MFA and 15Kh2NMFA steels after their irradiation in the core on the boundary with reflector and in the reflector in the WWR-M reactor channels with differing neutron spectra are determined. Thermal treatment was conventional for these steels. The irradiation was realized at the temperatures of 50-60 deg C and 270 deg C. It is shown that embrittlement and strengthening during irradiation in the reactor reflector are higher than during irradiation by the same neutron fluence in the core. The effect of the irradiation spectrum influence at 50-80 deg C is considerably higher than at 270 deg C and varies from 40 to 100 deg C for the heats investigated in case of the fluence of 4.1019 neutron/cm2. At 270 deg C the maximum excess of critical temperature of brittleness ΔTC during irradiation in the reflector as compared with irradiation in the core constitutes 25 deg C. For 15Kh2MFA-A steel at the same temperature the increase in ΔTC is insignificant. Theoretical explanation of the observed effect of the irradiation spectrum influence is suggested