V.M. Novikov

Calculated neutron transport verifications by integral 14 MeV-neutron source experiments with multiplying assemblies

This paper is devoted to a comparison of the experimental and calculated leakage neutron spectra and total neutron leakages from U, Th, Pb and Be spherical assemblies and also to a comparison of experimental and calculated reaction rates in U and Th assemblies. It was shown that the calculation with ENDF/B-IV data describes the shape of the neutron spectrum better for all considered materials. The full multiplication of neutrons for the U assembly is reproduced more accurately by the calculation with ENDL-75 data, and for Th, Be and Pb assemblies, by the calculation with ENDF/B-IV data.

An all-wave multicomponent activation detector

An all-wave multicomponent neutron activation detector was proposed which measured in a simple manner the total flux of fast neutrons within the interval 0.1-15 MeV. Cross sections for various sets of target detectors were determined. The detectors which formed part of the all-wave detector were irradiated either in succession or simultaneously in a fixed space of the assembly to be examined. The absolute rate of each reaction was measured and the corresponding corrections for self-absorption of gamma quanta, the quantum yield, and the recording efficiency for gamma quanta in the spectra were introduced. The absolute reaction rates were multiplied by the corresponding weights and resulting values were added. As a result, the rate of the activation reaction of the all-wave detector was obtained. Measurement of the neutron flux in a thermonuclear reactor blanket model with a characteristic response interval of 0.05-0.1 MeV up to 15 MeV was considered.

Verification of neutron spectrum calculation accuracy with the help of the spectral indices in the interval 1–14 MeV

Abstract This article is devoted to spectral indices measurements. The index is the saturation activities ratio of activation detectors in the neutron spectrum of an assembly, divided by this ratio in a certain standard neutron spectrum. This method was used in an experiment with a LiFBeF 2 assembly. The experimental results are compared with numerical datas obtained from calculations. It is shown that the experimental values of the spectral indices are above the calculated values in the energy range 1–10 MeV.

A fast neutron spectrum unfolding method using activation measurements and its application to restoration of a thermonuclear reactor blanket neutron spectrum

Abstract This article describes a fast neutron spectrum unfolding program. The program takes into account a priori information about the neutron spectrum, the experimental values of activation integrals errors and activation detector cross sections errors. The usefulness of the unfolding program was demonstrated by its application to the determination of neutron spectra from 1 to 14 MeV in the molten-salt blanket model of a thermonuclear reactor.