The Efficiency of Radiation Shielding Made From Materials With High Atomic Number and Low Mass Density

Abstract

The radiation shielding from γ-quanta of the existing transport containers (TC) for transportation of spent nuclear fuel (SNF) is made of steel or steel plus Pb 25…30 cm thick and weighting ~ 60…80 t. The application of materials with high atomic number, dispersed (solids grinded to a powdery state) to the densities in the range 4 < ρ < 8 g/cm3, is investigated. Simulations based on the Monte Carlo method show that at the densities of dispersed depleted U larger than 5 g/cm3 and shielding thicknesses of more than 30 cm, the absorption of γ-quanta of SNF is greater than that of the shielding made of steel of the same thickness. The application of such materials, while the weight characteristics of the shields are not exceeded, provides radiation shielding for SNF with the high burnup rate and the smaller cooling time or larger amount of the transported SNF.

EFFICIENCY OF COMBINED Fe AND Pb RADIATION SHIELD OF TRANSPORT CASKS FOR SNF TRANSPORTATION

“…Table 1 lists the main characteristics of these isotopes: half-lives T 1/2 > 1 year, energies of -quanta whose quantum yields are greater than 5% of the total yield Yi. The spontaneous fission of 244 Cm, the half-life of which is 18.1 years, is the main source of neutrons produced by SNF (about 97.4%) [9]. The neutron spectrum of spontaneous fission of actinides is similar to the spectrum of stimulated fission of 235 U and is approximated by the relation…”