고리1호기 원자로구조물 재료 조사손상 및 방사화 평가 = Radiation Damage and Activation of Reactor Internal Materials in Decommissioned Kori Unit 1

다국어 초록 (Multilingual Abstract)

Kori Unit 1, the first nuclear power plant in Korea, was permanently shut down in June 2017 after 38 years of commercial operation. We are planning to conduct materials degradation research by using the reactor components from Kori Unit 1. To proceed effectively, we first reviewed the foreign programs utilizing the decommissioned nuclear reactors. This paper considered two key factors in evaluating the properties of harvested components: radiation damage and activation of the neutron-irradiated material. The radiation damage to three reactor structures – the baffle, barrel and pressure vessel in Kori Unit 1, exposed to neutrons during operation was quantified using the SPECTER code. The maximum damage to the baffle material of stainless steels was evaluated to be approximately 70 dpa, which is 3.6 times higher than that to the baffle withdrawn from the Zorita Nuclear Power Plant in Spain. Also the amount of transmutation gas of helium and hydrogen, generated within the material during operation, was estimated, which can be useful in the annealing experiment for irradiated components. Using the NAC code, we identified the radioisotopes contained in neutron-irradiated materials and calculated their activity at 10 years of cooling time. This information is necessary for calculating the radiation exposure to the workers and for disposing the radioactive waste after test.