Calculation of ambient dose equivalent (individual) rate of neutron radiation based on the spectrum measurements techniques

S.G. Fedorov1, 2, A.V. Berlyand1, V.M. Dyachenko1

1FSUE “VNIIFTRI”, Mendeleevo, Moscow region, Russia
2National Research Nuclear University «MEPhI», Moscow, Russia,,

Al’manac of Modern Metrology № 3 (27) 2021, pages 46–61

Annotation. Measurement of the neutron spectrum is required to determine the values of ambient dose equivalent rate and individual dose equivalent rate of neutron radiation. A multi-ball spectrometer is used to determine the neutron spectrum at VNIIFTRI. Research has been carried out on the use of lithium glass scintillators as a detector of a spectrometer. For this, a calculation was made using numerical methods (Monte Carlo method) of the energy dependence of the sensitivity (ESP) of lithium glasses with a set of spherical moderators for their use as a detector in a multi-sphere neutron radiation spectrometer. The analysis of factors that introduce uncertainty into the values of the ESP function is carried out. The contribution to uncertainty from influencing factors was calculated by varying the values of the density of polyethylene, the atomic concentration of lithium-6. Measurements of neutron spectra in the collimated field of neutron radiation from the 238Pu-Be radionuclide source have been performed. Based on the calculated data on the values of the ESP function of lithium glasses and experimental data, the spectrum of neutron radiation was reconstructed and the values of the powers of the ambient and individual equivalent doses of neutron radiation were calculated.

Key words: neutron radiation dosimetry, neutron radiation spectrometry, scintillation detectors, energy dependence of sensitivity, Monte Carlo method.

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