Which Is More Essential for Immobilized Radioactive Waste Form: Durability or Impermeability?

Before the answer of this question, which of them is more essential for immobilized radioactive waste form durability or impermeability, it could be favorable to give a brief background about radioactive wastes and its immobilization. A rapid industrial growth and high technological progress are the main sources of the accumulation of these hazardous materials. Nuclear applications have been rapidly developed recently, and several nuclear power plants have been started to work throughout the world.

Investigation of Heat Effect on the Shielding Properties of Some Local Concretes

The effect of heat on gamma ray and fast neutron shielding properties of two types of the local concretes (basalt concrete; ρ=2.2 g/cm³ and magnetite concrete; ρ=3.9 g/cm³) with two different water to cement ratios for both were investigated. The samples were exposed to temperatures between 20 to 300°C and 800°C.

Small losses in attenuation coefficients for gamma rays and fast neutrons were observed for the studied types of concretes. Investigations have been performed using a narrow beam of Cs-137 source and a collimated beam from ET-RR-1 reactor. A gamma spectrometer with NaI (Tl) detector and a neutron-gamma spectrometer with stilbene scintillator were used during measurements.

Reactor Fast and Slow Neutrons and Total Gamma Rays Distributions through Different Locally Prepared Concretes

BA study of the penetration of reactor fast, slow neutrons and total gamma rays through two new types of locally prepared concretes (basalt concrete, ρ=2.2 g/cm3 and magnetite concrete; ρ=3.9 g/cm3) has been carried out. Investigations have been performed in order to obtain the leakage spectra of fast, slow neutrons and gamma rays beams from cylindrical samples of these concrete shields using a collimated beam from ET-RR-1 reactor.

Design Options of Control Rod for Low Enriched Uranium Fueled NIRR-1 Using Monte Carlo N-Particle Code

NIRR-1 like other Commercial MNSRs has single control rod performing all safety functions. Feasibility studies have shown that UO₂ fuel enriched to 12.5% can be used for the conversion of MNSRs to LEU. However, this conversion would require modification to the single control rod to maintain same safety margins as the current HEU core. Consequently, the MCNP Code was used to design 3 variants of control rod for proposed LEU Core. Since the main objective of conversion is simply to propose replacing the existing HEU core, the control rods were designed to fit into the existing core configuration. Neutronics calculations for the third case indicate that the shutdown margin and safety reactivity factor are equal to or greater than the data for the current HEU core.

Leachability of Solidified Degraded Radioactive Cellulose-Based Wastes

Cellulosic wastes are considered as one component of radioactive solid wastes generating during daily peaceful applications of nuclear materials. In the current article, the residual waste solution arising from the wet oxidative degradation of mixed cellulosic wastes(towel paper, filter paper and spent cotton clothes) using hydrogen peroxide as oxidant under 100°C and atmospheric pressure was solidified/stabilized through incorporation into a Portland cement matrix. Leachability as one of the most important characterizations of the final solidified radioactive waste form was evaluated to meet the final disposal requirements.