Wolsong unit 1, the first PHWR (Pressurized Heavy Water Reactor) in Korea, was permanent shut down in 2019. In Korea, according to the Nuclear Safety Act, the FDP (Final Decommissioning Plan) must be submitted within 5 years of permanent shutdown. According to NSSC Notice, the types, volumes, and radioactivity of solid radioactive wastes should be included in FDP chapter 9, Radioactive Waste Management, Therefore, in this study, activation assessment and waste classification of the End shield, which is a major activation component, were conducted. MCNP and ORIGEN-S computer codes were used for the activation assessment of the End shield. Radioactive waste levels were classified according to the cooling period of 0 to 20 years in consideration of the actual start of decommissioning. The End shield consists of Lattice tube, Shielding ball, Sleeve insert, Calandria tube shielding sleeve, and Embedment Ring. Among the components composed for each fuel channel, the neutron flux was calculated for the components whose level was not predicted by preliminary activation assessment, by dividing them into three channel regions: central channel, inter channel, and outer channel. In the case of the shielding ball, the neutron flux was calculated in the area up to 10 cm close to the core and other parts to check the decrease in neutron flux with the distance from the core. The neutron flux calculations showed that the highest neutron flux was calculated at the Sleeve insert, the component closest to the fuel channel. It was found that the neutron flux decreased by about 1/10 to 1/20 as the distance from the core increased by 20 cm. The outer channel was found to have about 30% of the neutron flux of the center channel. It was found that no change in radioactive waste level due to decay occurred during the 0 to 20 years cooling period. In this study, activation assessment and waste classification of End Shield in Wolsong unit 1 was conducted. The results of this study can be used as a basis for the preparation of the FDP for the Wolsong unit 1.

This study is about the production of radiation sources of simulated concrete and soil reference materials to verify the validity of the quality establishment and measurement of the detector (HPGe) of the radioactive soil and concrete waste classification system, which is being developed to quickly and accurately classify nuclear decommissioning waste. Specific activity of gamma nucleus among radioactive wastes is evaluated using gamma spectroscopy. At this time, in order to verify the validity and reliability of measuring equipment, it shall be a standardized substance of the same medium as nuclear decommissioning waste (chemical ingredients, particles, density, etc.) in order to correct the energy and efficiency of gamma nuclide analysis equipment. The CRM used for the detector’s energy correction used a 1 L Marinelli beaker standard correctional radiation source consisting of 10 radioactive isotopes. In order to correct efficiency, in accordance with the production and certification process of the Korea Standards and Research Institute, it has produced artificial simulated radioactive concrete similar to nuclear decommissioning waste (30% for cement, 60% for regulation and 10% for bentonite). The radioactive homogeneity of the simulated concrete reference materials was evaluated using dispersion analysis (ANOVA) in accordance with ISO Guide 35, while 137Cs and 60Co of concrete reference materials were able to obtain homogeneous measurements both in and between bottles. The self-absorption rate of the simulated concrete reference material was determined by the MCNP computer simulation measurement method, and the self-absorption correction coefficients of 137Cs and 60Co were assessed at 0.995 and 0.996, respectively, and the standard value for the radiation of the simulated concrete reference material was calculated on the weighted average of the measurements of 20 samples. The uncertainty about the reference value was calculated by combining measurement uncertainty (Type B evaluation), bottle to bottle standard deviation, and uncertainty within bottle by modifying the formula suggested in ISO Guide 35. The concentration of 137Cs and 60Co of reference materials was divided into high-speed measurement mode and precision measurement mode in consideration of the self-disposal standard. The reference value and uncertainty of expansion among reference materials for high-speed measurement mode were rated at 1,032.7 ± 64.0 Bq·kg−1and 1,083.7 Bq·kg−1, respectively. The standard value and expansion uncertainty for 137Cs and 60Co among reference materials for precision measurement mode were rated at 113.7 ± 10.0 Bq·kg−1 and 122.3 ± 10.3 Bq·kg−1, respectively.

국내의 중저준위 방사성폐기물 처분시설에 대한 핵종량은 대부분의 방사성핵종에 대한 규명이 요구되어 진다. 본 논문에 서는 국내 경주 처분시설 부지에서 방사성폐기물의 처분을 위한 처분시설의 활용도 및 효율성 그리고 신분류기준을 반영한 핵종재고량을 예측하였다. 장기 방사성폐기물의 예측하기 위해 2014년까지 다양한 발생원별 방사성폐기물의 발생량과 발 생전망을 분석하였다. 예측된 핵종재고량 결과는 처분시설에 대한 안정적인 개발 및 Safety case의 구축하는데 기여할 것으 로 판단된다.

Since the commercial operation of Kori Unit #1 nuclear power plant(NPP) started in 1978, 23 units at present are operating in Korea. Radioactive wastes will be steadily generated from these units and accumulated. In addition, the life-extension of NPPs, construction of new NPPs and decontamination and decommissioning research facilities will cause radioactive wastes to increase. Recently, Korea has revised the new classification criteria as was proposed by IAEA. According to the revised classification criteria, low-level, very-low-level and exempt waste are estimated to about 98% of total disposal amount. In this paper, current status of overseas cases and disposal method with new classification criteria are analyzed to propose the most reasonable method for estimating the amount of decommissioning waste when applying the new criteria.

산업단지에 입주한 업체에서 발생되는 폐수는 업종별로 성상이 다양하고 같은 성분이라도 수십배의 함량차이를 보이고 있어 대부분의 산업단지 폐수종말처리장에서는 안정적인 처리 효율을 유지하기 위해 업체별로 개별 처리한 처리수를 폐수종말처리장으로 유입시켜 처리하고 있는 실정이다. 따라서 폐수 발생 업체들은 폐수를 생물학적 방법, 물리･화학적인 방법을 이용하여 폐수를 처리하고 있으며, 화학적 처리 방법을 채택하고 업종이 많은 것으로 알려져 있다. 주를 이루고 있다. 한편 폐수 처리 과정에서 발생되는 슬러지는 자체 처리하는 경우도 있지만, 대부분 탈수 처리한 후에 지정 페기물 해당 여부에 따라 상이한 방법에 의해 위탁 처분되고 있다. 그러나 이러한 폐수 처리 과정에서 발생되는 슬러지의 성상에 대해서는 지정 폐기물 해당 여부를 판단하기 위한 자료만 있으며, 지정 폐기물 기준 항목 이외의 성분에 대한 다양한 정보와 축적된 자료가 전무하여 발생 슬러지에 대한 체계적으로 관리하기에는 한계가 있다. 따라서 산업단지내 업종별 발생 슬러지의 특성을 파악하고 이들 슬러지 관리 체계의 구축을 위한 기초적 자료를 확보하기 위해 대구지역 S 산업단지내에 입주하고 있는 폐수 발생 업체 중 18업체(6개 업종)에 대해 원수, 처리수 및 슬러지를 채취하여 그 성상을 비교･검토하였다. 연구 대상 업체에 대한 슬러지를 조사･분석한 결과, 염색 업종은 상대적으로 알루미늄의 함량이 높은 것으로 나타났으며, 일부 업체는 100g/kg을 상회하였다. 특히 도금 업종에서는 300g/kg을 상회하는 업체도 있는 것으로 나타났다. 철은 조립 금속 업종에서 가장 많이 함유된 것으로 나타났으며, 칼슘의 함유량은 대부분의 업종에서 높게 나타났다. 그리고 석유 화학 업종이 타 업종에 비해 인의 함유량이 높은 것으로 나타났다, 검토한 업종별 슬러지에서 100g/kg을 상회하는 함유량을 보인 성분은 알루미늄, 철, 크롬, 칼슘이었다. 알루미늄, 철, 칼슘은 대부분 폐수의 처리 과정에서 투입된 응집제에서 기인된 것으로 판단되며, 크롬은 도금 업종에서 배출된 것으로 나타났다.