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The radioactive aerosol generated by the Nuclear Power Plant (NPP) decommissioning process can be inhaled by workers and deposited inside the human body, resulting in internal exposure. Because internal exposure, unlike external exposure, is difficult to measure directly, it is all the more necessary to assess the dose workers receive as a result of internal exposure. Precise assessment of the internal exposure necessitates actual measurements in the work environment such as the workers’ respiration rate, kind of nuclide and amount of captured nuclide. However, in the event of difficulties in securing these measurements, the internal exposure dose can be estimated based upon the recommended values by the ICRP (International Commission on Radiological Protection) such as the intake fraction and particle size. In this study, 5 μm was selected as the particle size as recommended by the ICRP, and both heavy and light respiratory rates were used in the calculation. With respect to the nuclides contained in the radioactive aerosol and their concentrations, the data captured for the aerosol in the melting facility on the Kozloduy NPP premises in Bulgaria were applied to estimate workers’ internal exposure. As a result, each worker was found not to have received more than 20 mSv/yr, which is the maximum annual permissible dose for workers.

>> In D-T fusion reaction, D2 (duterium) and T2(tritium) are used as fuel gas. The exhaust gas of nuclear fusion includes hydrogen isotopes Q2 (Q means H, D or T), tritiated components (CQ4 and Q2O), CO, CO2, etc. All of hydrogen isotopes should be recovered before released to the atmosphere. This study focused on the recovery of hydrogen isotopes from CQ4 and Q2O. Two kinds of experiments were conducted to investigate the catalytic reaction characteristics of SMR (Steam Methane Reforming) and WGS (Water Gas Shift) reactions using Pt catalyst. First test was performed to convert CH4 into H2 using 6% CH4, 6% CO / Ar feed gas. In the other test, 100% CO gas was used to convert H2O into H2 at various reaction conditions (reaction temperature, S/C ratio, GHSV). As a result of the first test, CH4 and CO conversion were 41.6%, 57.8% respectively at 600°C, S/C ratio 3, GHSV 2000 hr -1. And CO conversion was 72% at 400°C, S/C ratio 0.95, GHSV 333 hr -1 in the second test.

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