METHOD OF DETERMINING ISOTOPE RADIO OF FISSILE MATERIAL CONTAINED IN FISSION CHAMBER Russian patent published in 2014 - IPC G01T3/00 

FIELD: physics, atomic power.

SUBSTANCE: invention relates to a method of determining the isotope ratio of fissile material. The method of determining the isotope ratio of fissile material contained in a fission chamber, wherein the fissile material has a main isotope X and at least one impurity isotope Y, and wherein isotopes X and Y have radioactive decay according to the following two equations: X->X', characterised by λ_x, F_x, and Y->Y', characterised by λ_Y, F_Y, where X' and Y' are daughter isotopes of isotopes X and Y, wherein the decay of isotope X (respectively Y) is characterised by emission of a gamma particle by daughter isotope X' (respectively Y′) at an energy E₁ (respectively E₂) with a probability of emission I_γ(E₁) (respectively I_γ(E₂)), where the values λ_X and λ_Y are, respectively, the radioactive decay constant of main isotope X and the radioactive decay constant of impurity isotope Y, and F_X and F_Y are, respectively, an isotope decay branching factor used for measurement of main isotope activity and an isotope decay branching factor used for a measurement of impurity isotope activity, the method comprising: measurement, using a spectrometry apparatus put in a given measurement configuration, of a net area S(E₁) of a first gamma peak of the fissile material at a first energy E₁ and of a net area S(E₂) of a second gamma peak of the fissile material at a second energy E₂; determination, using reference point sources, in the given measurement configuration, of a total reference absorption efficiency $$R_O^P\left(E_1\right)$$ at the first energy E₁ and a total reference absorption efficiency $$R_0^P\left(E_2\right)$$ at the second energy E₂; calculation, using a computer, in the given measurement configuration, of a total efficiency transfer T(E₁) of the fissile material at the first energy E₁ and a total efficiency transfer T(E₂) of the fissile material at the second energy E₂; and calculation, using a computer, of the isotope ratio R of fissile material using the following equation: $$R=\frac{{\lambda }_X}{{\lambda }_Y}\times \frac{S\left(E_2\right)}{S\left(E_1\right)}\times \frac{I_{\gamma }\left(E_1\right)}{I_{\gamma }\left(E_2\right)}\times \frac{R_0^P\left(E_1\right)}{R_0^P\left(E_2\right)}\times \frac{T\left(E_1\right)}{T\left(E_2\right)}\times \frac{F_X}{F_Y}.$$

EFFECT: high efficiency of determining the isotope ratio of fissile material.

6 cl, 5 dwg