Fast Reactors and Accelerator Driven Systems Knowledge Base
Conference Article: Research on accelerator driven systems in the National Academy of Sciences of Belarus
S.E. Chigrinov, A.I. Kievitskaia, I.L. Rakhno, I.G. Serafimovich, C.K. Rutkovskaia (Radiation Physics & Chemistry Problems Institute, National Academy of Sciences, Minsk-Sosny, Belarus), A.M. Khilmanovich, B.A. Marstinkevich (Institute of Physics, National Academy of Sciences, Minsk, Belarus)Abstract
By now a lot of theoretical papers was published where basic aspects of ADS concept were discussed:
production of energy, transmutation of radioactive waste, tritium production and incineration of
weapon plutonium. The experimental research in this field is rather scare because the experiments on
available high energy accelerators are difficult and expensive, and in some case even unfeasible. In
this regard experimental research of various aspects of ADS on the basis of low energy ion
accelerators are of great importance. The possibility of using low energy accelerators to investigate
physical characteristics of subcritical target/blanket systems follows from the mechanism of nuclear
reactions in high (0.8 - 2 GeV) and low (15-20 MeV) energy ranges as well as from features of
nucleon-meson cascade development. It was the foundation for creation of an experimental facility
consisting of a uranium-polyethylene subcritical assembly (maximal multiplication factor ˜ 0,975)
driven by high intensity (˜1.5×1012 n/s) neutron generator. The core is a rectangular prism having base
400 x 400 mm and height 570 mm. It is assembled from polyethylene blocks with the channels to
place the fuel pins disposed in a rectangular lattice with pitch equal to 20 mm. The fuel pins are made
of UO2 with enrichment equal to 10% in 235U. The subcritical assembly contains 265 fuel pins. Central
part of the blanket is a neutron producing lead target 10 cm in diameter and 60 cm in length. There are
four channels for location of detectors of neutron flux level control. For irradiation of investigated
samples the experimental channels with diameter of 25 mm are located at subcritical assembly radii 5,
10, 16 cm. The core is placed in a well of a stack of graphite bricks serving as lateral reflector.
Calculations have shown that energy spectrum of neutrons in the thermal assembly is unique one and
differs from energy spectra in thermal reactors. Namely in the energy range from 1 to 104 eV
dependence of neutron flux on energy is very weak what allows to get data on neutron cross sections
for a resonance region. Measurements of energy spectra at different points inside experimental
channels will be performed by means of activation technique having different advantages comparing
to other techniques. At present experiments on measurement of transmutation rates of long-lived
fission products ( 129I, 135Cs, 126Sn,....) and minor actinides (237Np) are being planned.
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key words: Fast Neutron Spectrum Systems, Nuclear Technology