• 대한방사선기술학회지:방사선기술과학
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• 제41권1호
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• pp.67-73
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• 2018

In this paper, risk assessment was conducted to verify self - disposal requirements by landfill for exempted incineration ash by using Resrad Ver.6.5 computer code. The result of risk assessment by landfill for the incineration by-product is that individual dose is $6.91{\times}10^{-2}{\mu}Sv\;y-1$ and collective dose is $3.475{\times}10^{-7}man-Sv\;y-1$. It proved that the result meets reference dose of individual dose $10{\mu}Sv\;y-1$ and collective dose 1 man-Sv y-1 for general public. According to the current 'Nuclear Safety Commission Notice [No. 2014-3]', it states that the exempted wastes can be disposed of by incineration, landfill and recycling. However, most of recently documents and papers related to exempted wastes are disposed of by landfill and recyling and it could not confirm the case of exempt by incineration. If the national consensus is derived and treating the waste by using process of incineration is activated, it could be considered to treat low level of radiation wastewater and activated carbon excluded from exempted waste because of nuclide $^3H$ and $^{14}C$.

• 한국안전학회지
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• 제32권2호
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• pp.1-6
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• 2017

Modern society has been experiencing by population growth and urbanization that bring, a change of eating habits which has occurred a various types of waste in a large amount. Even though these wastes are required an immediate treatment with difficulties unsanitary handling and existing waste treatment method are by incineration, fermentation, drying and etc. however a bad smell occurs after the treatment that need's a lot of energy in processing organic wastes with high moisture contents and wasteful and inefficient problem. The strength assessment of the organic waste agitating vessel is required in terms of safety due to the differences of loading on the shaft that was treated by agitating the mixture of food waste. The damage of agitating axis is depended on steam pressure, temperature condition and the force moment that exerted by the food waste. Thus the strength assessment and stability evaluation are very important, especially to handle a hard waste. In this study the rotation capacity of agitation is about 5 tons considering general structural rolled steel pressure vessel strength and steam pressure. The purpose is to estimate the safety and strength evaluation for a agitator axis and impellers according to the rotating angle of the axis under the condition of the 3.2 ton capacity reactor.

• 한국산업보건학회지
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• 제23권2호
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• pp.84-94
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• 2013

Objectives: The objective of this study is to identify the composition of dominant microorganisms in waste handling industries. Methods: We collected airborne bacteria and fungi by agar plate impaction method in recyclable waste sorting industry, food recycling industry, landfill and incineration. Isolated dominant microorganisms were identified by VITEK system or morphological analysis. Results: We isolated totally 330 microorganisms in the process and outdoor. Bacillus was the most dominant genus in the all industries, and Sphingomonas, Acinetobacter, Staphylococcus, and Proteus was dominant bacterial genus. The dominant genus of fungi was Penicillium, Aspergillus, and Cladosporium in each industries. Enterobacter, Pseudomonas, Klebsiella, and Proteus was identified as the dominant gram negative bacteria. The ratio of bacteria being biosafety levels(class 1 or 2) was 58.3~77.8%. Conclusions: This study has investigated the dominant microorganisms in the waste handling industries. The genus of dominant microorganisms was similar among the industries but the composition was different. We used biosafety levels as qualitative method, but further studies are needed about specific process of qualitative evaluation methods.

• 대한방사선기술학회지:방사선기술과학
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• 제40권4호
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• pp.633-638
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• 2017

방사선 진료기술의 발전에 따라 의료분야에서 발생하는 방사성폐기물이 급속히 증가하고 있다. 최근의 경향을 보면, 갑상선암 진료 목적의 I-131을 비롯하여 PET/CT 조영제로 사용하는 F-18, 핵의학검사에 폭 넓게 적용하는 Tc-99m 등의 방사성동위원소 사용이 일반화 되고 있다. 사용과정에서 이러한 핵종에 오염된 방사성폐기물이 발생하게 되는데, 일정기간 보관한 후에 방사능이 규제해제(Clearance) 수준으로 감쇠하면 소각 등의 방법으로 자체처분하게 된다. 국제원자력기구(IAEA)에서는 $10{\mu}Sv/y$의 개인선량 및 1man-Sv/y의 집단선량과 함께 핵종별 농도에 근거하여 방사성폐기물의 규제해제기준을 제시하였다. 이 연구에서는 IAEA의 핵종별 방사능농도기준에 따른 규제해제 시점을 확인하기 위하여, Tc-99m과 방사화학상유사한 성질을 가지고 있는 Re-186 관련 방사성폐기물을 수집하여 방사능을 측정하였다. Re-186은 반감기가 3.8일로 방사성의약품으로는 비교적 길고, 베타선 및 감마선을 방출하여 방사성의약품 치료와 영상에 모두 사용된다. Re-186 사용과 관련하여 발생하는 오염된 일회용장갑(Poly Glove)의 방사능측정을 위하여 다중파고분석기(Multi Channel Analyzer; MCA)를 이용하였으며, 이를 위하여 표준물질을 제작하여 MCA를 교정한 이후 감마방사능 측정절차에 따라 수행하였다. 측정결과를 근거로 방사능 감쇠 유도식을 산출하여 이론식과 대비하여 고찰하였는바, Re-186 핵종의 유도반감기(3.6일)는 이론적 반감기(3.8일)에 비해 다소 짧은 것으로 나타났다. 따라서 측정결과에 근거한 유도반감기를 적용한다면, 다소 줄어든 기간 동안 Re-186 핵종 폐기물을 보관하였다가 자체처분을 할 수 있을 것으로 확인하였다. 이 연구 결과는 현재 추진하고 있는 국제표준화기구(International Organization for Standardization) 국제표준에 포함될 예정이다.