Radiation shielding assessments may underestimate the expected dose if some isotopes at trace level are not considered in the isotopes inventory of the shielded radioactive materials. Indeed, information about traces is not often available. Nevertheless, the activation of some minor isotopic traces may significantly contribute to the dose build-up. This paper presents a new method (Isotopes Inventory Reconstruction-IIR) estimating the concentration of the minor isotopes in the irradiated material at the beginning of the cooling period. The method requires the solution of the inverse problem describing the irradiated material's decay. In a mixture of an irradiated uranium-plutonium oxide shielded by a set-up made of stainless-steel, porous polyethylene plaster and lead methyl methacrylate, the comparison between different methods proves that the IIR-method allows better assessment of the dose than other approximate methods.

Abstract-TRIPOLI-4R is a Monte-Carlo particle-transport code developed at CEA-Saclay (France) that is employed in the domains of nuclear-reactor physics, criticality-safety, shielding/radiation protection and nuclear instrumentation. The goal of this paper is to report on current developments, validation and verification made in TRIPOLI-4 in the electron/positron/photon sector. The new capabilities and improvements concern refinements to the electron transport algorithm, the introduction of a charge-deposition score, the new thick-target bremsstrahlung option, the upgrade of the bremsstrahlung model and the improvement of electron angular straggling at low energy. The importance of each of the developments above is illustrated by comparisons with calculations performed with other codes and with experimental data.

Stochastic geometries in Monte-Carlo simulations enable to simulate complex configurations such as the repartition of possible radioactive dust in a glove box. This paper compares several dust models that represent more or less explicitly the heterogeneous repartition of dust speckles in space. Indeed, assessing the contribution of dust to the dose received by the hands of an operator is a key problem for glove boxes. Results show that homogeneous models generally overestimate the dose, which is correct for radioprotection studies, but that dust aggregates produce doses that are much smaller than those obtained by homogenising dust. These heterogeneous models can also help estimating deposited dust quantities from dose measurements inside the glove box, whereas an homogenous model would grossly underestimate dust quantity.