METHOD FOR SIMULTANEOUS REPRODUCTION OF GIVEN NEUTRON FLUENCE AND EXPOSURE DOSE OF GAMMA RADIATION AT RESEARCH REACTORS Russian patent published in 2019 - IPC G21K5/00 

FIELD: test technology.

SUBSTANCE: invention relates to a method for simultaneous reproduction of given neutron fluence (F_ni) and exposure dose of gamma radiation (D_ni) at research reactors. Method is based on superposition of fields of radiation from reactor and converters located outside sector of direct effect of reactor radiation of symmetrically active zone (AZ), determination of fluence of neutrons (F) with energies of more than 0.1 MeV and exposure dose (D) of gamma radiation at distances (r) along the normal passing through the center of the AZ to the longitudinal axis of the irradiation zone, with constant dimensions of the converters and the chosen arrangement of the converters, as well as dependencies F(r)/Q, D(r)/Q, j(G), C_D(S)=D(S)/D_p and C_F(S)=F(S)/F_p in double-side zone irradiation, where Q is energy released into AZ, S is converter thickness, j is parameter characterizing non-uniformity of distribution of F(r) and D(r) in irradiation zone, G is distance from center of AZ to external (remote from AZ) boundary of radiation zone, F_p, D_p and F(S), D(S) – fluences of neutrons and dose of gamma-quanta in a reference point at Q=1 J, standard thickness of converters and thickness S, respectively. Method then includes selecting reactor operation mode by formula P⋅t=F_ni/F_p⋅C_F, where P is reactor power, t is duration of irradiation, minimum width of irradiation zone is determined from dependence j(G), at which non-uniformity of distribution of parameters F and D does not exceed 30 %, and thickness of converters from C_D(S), where C_D=D_ni/D_p⋅P⋅t. Then, the IET is placed in the irradiation zone and irradiated at the selected reactor operation mode in series from two opposite sides.

EFFECT: reproduction of test standards in the irradiation zone with dimensions exceeding the dimensions of the unilateral irradiation zone in a wide range of values of F_ni/D_ni with simplified testing technology.

1 cl, 4 dwg