Comparing VVR-M reactor fuel assembly heat technological capabilities

Translated from Atomnaya Énergiya, Vol. 67, No. 2, pp. 97–100, August, 1989.     

Small-group model in calculating the critical mass of a VVR-M reactor

V. P. Konstantinov St. Petersburg Institute of Nuclear Physics. Translated from Atomnaya Énergiya, Vol. 75, No. 2, pp. 83–87, August, 1993.     

Release of tritium from boron carbide irradiated with reactor neutrons

The release of tritium from irradiated boron carbide in a pure Ar atmosphere was investigated between 500 and 900°C. The sintered B₄C samples with densities between 75 and 95% of the theoretical density were irradiated with reactor neutrons with total neutron doses up to 5 × 10²⁰/cm². Effective diffusion coefficients, D_eff, were derived from the release data using the model “diffusion out of a sphere”. D_eff decreases by about 3 orders of magnitude with increasing total neutron dose, levels off at about 10¹⁸n/cm² and increases at very high doses ( > 10²⁰ n/cm²). The decrease in the tritium mobility is attributed to the radiation defects formed in the B₄C. The activation energy of 210 ± 30 kJ/mol for the tritium diffusion in the irradiated B₄C is much higher than the value found for unirradiated material. D_eff depends also very strongly on the density of the sintered material.