Concrete radioactive waste is divided into surface-contaminated concrete and activated concrete, and although the generation rate varies depending on the operating conditions of the nuclear power plant, it is reported that the amount of surface-contaminated concrete generated is greater. It is reported in the ‘US-NRC Inventory Report’ that 99% of radionuclides in surface-contaminated concrete are distributed within 1 mm of the surface. Since concrete radioactive waste accounts for a large amount of generation after metal radioactive waste, it is necessary to reduce the amount of radioactive waste disposal by applying appropriate treatment techniques to surface-contaminated concrete. In this study, a similar contamination environment work space with the size of 5.4 (W) × 3.6 (L) × 2.5 (H) [m] in which concrete specimens can be fixed on the wall and floor was established. And an integrated decontamination equipment was verified the automation performance for ‘location accuracy’, ‘radioactive contamination level measurement’ and ‘concrete surface laser scabbling’. It was confirmed that the average was 8.3 [mm] in the evaluation of the ‘location accuracy’ for the remote control and movement of the integrated decontamination equipment. For performance verification of ‘radioactive contamination level measurement’ and ‘laser scabbling’, it were used that size of 30×30×8 [cm] ordinary concrete specimens and concrete radioactively contaminated with Co-60 below the regulatory exemption concentration. ‘Radioactive contamination level measurement’ is measured as much as the set range, divied and display the measured values in different colors on the map of the control program. Ordinary concrete specimens are 0.066~0.089 μ Sv/hr, and contaminated concrete specimens are 0.107~0.121 μ Sv/hr, and it was confirmed that they are expressed in different colors on the map. For ‘laser scabbling’, the performance according to the laser scabbling speed and reproducibility with ordinary concrete specimens was verified. As a result, a weight change of up to 1.48 kg was confirmed. Contaminated concrete specimens were subjected to a direct method using a surface contamination detector and an indirect method using a smear paper to measure surface contamination before and after scabbling, and the debris generated after scabbling was analyzed using HPGe.

Surface contaminants may attach to surfaces or objects in the radiation controlled area to cause radiation exposure, or spread out to the general environment by person and object exiting the radiation workplace. Accordingly, in radiological safety control, surface contamination monitoring is one of the important factors in workplace monitoring. When obtaining the measurement results for the monitoring, the results are accompanied by uncertainty since measurements contain numerous errors. Accordingly, the International Organization for Standardization (ISO) has published the ISO 7503 series which is comprehensive and detailed guidelines on the measurement and evaluation of surface contamination. ISO 7503-3 especially presents a mathematical model for the contamination measurement and provide calculation guidelines on measurement uncertainty evaluation, decision threshold and detection limit. This paper is focused on reevaluating and comparing the surface contamination monitoring method applied to radiation safety management practice and its results based on the measurement and evaluation method set by the International Organization for Standardization. The evaluation was performed in accordance with ISO 7503, and the current reporting method for measurement results was compared with the method recommended in ISO 11929 publication.

A large amount of concrete radioactive waste is generated during the decommissioning of nuclear facilities, including nuclear power plants, and it is expected that the radioactive waste management expenses will be huge. In order to reduce the concrete radioactive waste, a decontamination or removal process is required, but working on concrete may present a risk of worker exposure in a high-radioactive space. Therefore, in this study, a remote control integrated decontamination equipment that can reduce concrete radioactive waste and ensure the safety of workers during the concrete decontamination process in a high-radioactive space was developed. The integrated decontamination equipment consists of remote movement, automatic surface contamination measurement, automatic surface decontamination and debris/dust removal systems. The remote movement system generates ‘mapping data’ of topographic features for the work space and ‘location data’ that coordinates the location of the integrated decontamination equipment through LiDAR (Light Detection and Ranging) sensor and SLAM (Simultaneous Localization And Mapping) technique. The user can check the location of the integrated decontamination equipment through ‘location data’ outside the work space, and can move it by remote control through wired/wireless communication. The automatic surface contamination measurement system uses a radiation detector and an automatic measurement algorithm to generate ‘surface measurement data’ based on the measurement distance interval and measurement time set by the user. ‘Surface measurement data’ is combined with ‘location data’ to create a visualized map of radioactive contamination, and users can intuitively realize the location and degree of contamination based on the map. The automatic surface decontamination system uses a laser and an automatic removal algorithm to decontaminate the concrete surface. Concrete debris and dust generated during this process were collected by the debris/dust removal system, minimizing waste generation and radiation exposure due to secondary pollution. The integrated decontamination equipment developed through this study was applied with technologies that reduced radioactive concrete waste and ensured the safety of workers. If technology verification and on-site applicability review are performed using concrete specimens simulating nuclear power plant or similar environments, it is reasoned to contribute to the domestic and overseas decommissioning industry.

The purpose of this study was to investigate the effects of ionized calcium treatment on total bacterial cross-contamination of chicken carcass surface in the slaughtering process. The growth of Escherichia coli was strongly inhibited in a medium prepared by using a 0.5% ionized calcium solution. The total bacterial cross-contamination of chicken carcass surface and the scalding water was significantly increased as the number of scalding was increased (p<0.05). The total bacterial cross-contamination of chicken carcass surface reached a plateau without a further increase as scalding was performed consecutively for 10 or more times. The total bacterial cross-contamination of the scalding water was significantly increased as the number of scalding was increased (p<0.05). The total bacterial cross-contamination of chicken carcass surface of the chickens raised on a floor type farm was significantly higher than that of the chickens raised in a battery cages (p<0.05). The total bacterial cross-contamination of chicken carcass surface of the chickens raised on a floor type farm was significantly lower in the 0.5% ionized calcium solution treatment group than in the control group (p<0.05).

광주광역시 하천에 분포하는 표층퇴적물의 지구화학적 특성을 살펴보기 위하여 영산강 본류, 황룡강, 광주천에서 채취한 시료를 대상으로 입도, 금속원소, 유기탄소의 함량에 대한 분석을 실시하였다. 퇴적물의 입도는 잔자갈에서 니질 크기로 다양하게 나타났다. 퇴적물 내 금속원소의 함량변화는 영산강 본류와 황룡강에서는 퇴적물 입도와 주변 지질에 의한 의존성을 보였다. 광주천에서는 생활하수 등의 유기물에 의한 많은 영향을 받은 것으로 나타났다. 퇴적물에 함유된 금속원소들의 오염을 알아보기 위한 부화계수와 농집지수는 영산강 본류와 황룡강이 특별하게 오염되지 않음을 지시한다. 그러나 광주천에서는 부화계수가 P=8.30, Cu=5.54, Zn=14.28, Pb=7.41 등으로, 농집지수는 P=3.78, Cu=2.79,Zn=3.66, Pb=1.59 등을 보였다. 특히, 광주천의 지류인 서방천과 동계천 등이 유입되는 지점에서 중금속 오염이 상당히 진행된 것으로 보여진다. 따라서, 광주광역시를 관류하는 하천들의 금속오염은 상당 부분 도시지역의 생활 하수에서 비롯된 것으로 판단된다.

In order to analyze the water quality variation of surface water around the Sudokwon landfill site, seasonal variations of water temperature, pH, DO, BOD, COD, SS, NH_3-N. NO_2-N, and NO_3-N were examined at 10 sites from January to December, 1996. It was found that the estimates of COD, DO, SS, and NH_3-N were increased compared with the results of environmental impact assessment carried out in 1988. Higher estimates of COD, DO, and SS were due to industrial and agricultural wastewater, and the increase of NH_3-N at Jangdo reservoir site was due to the leachate from the landfill. In particular, the estimate of SS was found to be increased by the soil wash from the landfill during the heavy rainy days.