Occupational internal exposure calculation during dismantling of bio-shield of Kori nuclear power plant unit#1

In this study, a dismantling scenario was developed, and the internal dose of a worker was estimated during bio-shield dismantling of Kori nuclear power plant unit#1 for radiological safety assessment internal exposure of workers to bio-shield dismantling. The internal dose was estimated from the analysis of radioactivity concentration of five main radionuclides (including 3H, 55Fe, 60Co, 152Eu, and 154Eu) of radioactive concrete using MCNP and the cutting scenario of a dismantling worker was designed. The internal dose of a worker during Diamond Wire Saw(DWS) cutting was calculated as 1.44 mSv for dry cutting and 5.03 μSv for wet cutting. The cutting time for dry cutting was 1.43 times higher and the air release fraction was approximately 200 times larger compared to wet cutting. Most of the calculated exposures were based on work conducted in a highly contaminated area; this work is expected to be completed within 2000 h. Therefore, the estimated results could be directly compared to the annual dose limits. The results of this study would be useful for the preparation of dismantling work procedures of the bio-shield of Kori nuclear power plant unit#1 in accordance with radiation safety measures.