Fusion safety studies in Russia in 2003

Abstract

The paper presents a review of the fusion safety studies performed in Russia in 2003. Among the findings is the effect of tungsten sputtering by subthreshold energy ions at high temperature, which tends to decrease with irradiation dose. The size distribution of W-erosion products (spherical droplets or flakes) depends on the positioning of the collector. Studies of Be + D(H) films revealed that D/Be ratio in co-deposited Be–D films decreases from 0.15 at 375 K to 0.05 at 575 K. Hydrogen concentration in Be + C films, exposed to acetylene ion flux at 670 K, decreased from 20–24 to 6 at.% with increase in irradiation dose from 10 23 to 10 24 m −2. The analysis of spectroscopic characteristics of C D films deposited inside the T-10 tokamak vacuum chamber provides qualitative insight into the physical and chemical reasons behind the preferential retention of the heavier hydrogen isotope in the tokamak erosion films. An extraction scheme for radiochemical reprocessing of activated V–Cr–Ti alloy after a fusion reactor decommissioning was developed and checked experimentally. It takes 48 extraction steps to recover V, Cr and Ti down to an effective dose rate <12.5 μSv/h, permitting the refabrication of these metals without any biological shielding from ionizing radiation.