There is a large amount of radioactive waste in waste storage in the Korea Atomic Energy Research Institute. Some of the radioactive waste was generated during the dismantling process due to Korea Research Reactor 1&2 and it accounts for 20% of the total waste. Radioactive waste must be reduced by appropriate disposal methods to secure storage space and to reduce disposal costs. Research Reactor wastes include wastes that are below the acceptable criteria for selfdisposal and non-contaminated wastes, so they can be treated as wastes subject to self-disposal through contamination analysis and reclassification. In order to deregulation radioactive waste, it is necessary to meet the self-disposal standards stipulated in the Domestic Nuclear Act and the treatment standards of the Waste Management Act. The main factors of deregulation are surface contaminant, radionuclide activity and dose assessment. To confirm the contamination of waste, surface contaminant and gamma nuclide analysis were performed. After homogenizing the waste sample, it was placed in 1 L Mariinelli beaker. When collecting waste samples, 1 kg per 200 kg of waste was collected. The concentrations of the major radionuclides Co-60, Cs-134, Cs-137, Eu-152, and Eu-154 were analyzed using HPGe detector. To evaluate radiation dose, various computational programs were used. A dose assessment was performed with the analyzed nuclide concentration. The concentrations of representative nuclides satisfied the deregulation acceptance criteria and the results of the dose assessment corresponding to self-disposal method was also satisfied. Based on this results, KAERI submitted the report on waste self-disposal plan to obtain approval. After final approval, Research Reactor waste is to be incinerated and incineration ash is to be buried in the designated place. Some metallic waste has been recycled. In this study, the suitability of deregulation for self-disposal was confirmed through the evaluation of the surface contaminant analysis, radionuclide concentration analysis and dose assessment.

It is important to make a strategy for clearance-level radioactive waste. Sampling and disposal plans should be drawn up with characteristics of target waste. In this paper, a target clearance-level radioactive waste is used in a laboratory for experiments with Cs-137 and Co-60, unsealed radioactive sources with gamma radiation isotopes. Therefore, it is enough to analyze with HPGe to check the contaminant level. The laboratory fume hood combined multiple materials, which means some are volume contamination and others are surface contamination. The wood, plastic, and drywall boards, which are absorbent volume contaminated parts and make up PVC pipes, base cabinet doors, backside baffles, etc., will be sampled with coring methods. The metals and glasses, which are unabsorbent, surface-contaminated parts, are sampled with smear methods. The work surface, baffles, exhaust plenum, and glass sash inside parts have a high possibility of being contaminated. The hood body, flame, base cabinet, PVC pipe (the rare end of the filter), and blower transition case have a low possibility of becoming contaminated. When we checked with HPGe, except for the work surface (which was below clearance level), other parts were less than MDA. The highest radionuclide concentration was in PVC pipe: Cs-137C 3.91E-02 (Bq/g), Co-60 4.54E- 03 (Bq/g). It is less than clearance level. Therefore, the waste was applied for the clearance level radioactive wastes and got permission from the regulatory body.

In general, dose assessment must be performed to obtain approval for clearance of radioactive waste. If the annual dose criteria through dose evaluation satisfies the clearance condition, radioactive waste can be disposed of. Various programs are used to perform dose assessment. NRCDOSE GASPAR is used as a program to assess the amount of radiation exposed to atmospheric emissions. Program is easy to use and results can be checked immediately after execution. GASPAR requires main input factors by exposure route such as site specifics, source term, special location, block data. Basically, program has default input values but user can easily modify it. The most important factor is that when entering a nuclide, the effect on progeny radionuclides is not automatically calculated. User should consider the dose contribution from progeny radionuclides. In this study, dose assessment was performed for combustible waste incineration using NRCDOSE GASPAR. And it was confirmed that exposure dose of individuals and groups criteria for clearance regulation.

In KAERI, Waste storage facility in the radiation management area has stored a large amount of wood waste. The amount of waste is approximately 27,000 kg, it accounts for 17% of the total waste in waste storage facility. Proper disposal of wood waste improves the fire resistance performance, secure storage space and reduce disposal costs. In order to self-disposal of wood waste, it is necessary to satisfy the self-disposal standards stipulated by the domestic Atomic Energy Act and the treatment standards of the Waste Management Act. The main factors of standards are surface contaminant, radionuclide activity and radiation dose effects. To confirm the contamination of wood waste, direct indirect measurement methods and gamma nuclide analysis were performed. To evaluate radiation dose, various computational programs were used. The results of the analysis were satisfied with domestic regulations on the classification and self-disposal of radioactive wastes. Based on this results, KAERI submitted the report on wood waste self-disposal plan to obtain approval. After final approval, wood waste is to be incinerated and incineration ash is to be buried in the designated place. The objective of this study is to provide total procedure of wood waste self-disposal and effective representative sampling method.

본 연구는 국화과 추출물 첨가가 in vitro 반추위 발효성상 및 메탄 발생에 미치는 영향을 구명하고자 수행하였다. 반추위액은 cannula 장착된 한우 암소 1두에서 채취하였으며, 공시축의 사양관리는 timothy와 농후사료를 6:4 비율로 하였다. 배양액은 Mcdougall buffer 10mL, 위액 5mL 섞어 50mL serum bottle에 혐기상태로 분주하였다. 티모시 0.3g를 각각 넣고 국화과 추출물인 국화, 민들레, 씀바귀, 제비쑥, 해바라기를 기질의 5%를 첨가한 뒤 발효시간대별(3, 6, 9, 12, 24, 48 및 72시간)로 7처리 3반복 수행하였다. 배양액 pH값은 6.29~7.44으로 반추위 적정 pH범위에 속하였다. 건물 소화율은 발효시간대가 늘어날수록 처리구에서 대조구에 비해 유의적(p<0.05)으로 증가하였다. 총가스 발생량은 발효 48시간대에서 민들레, 씀바귀, 제비쑥, 해바라기에서 대조구에 비해 유의적(p<0.05)으로 높게 측정 되었다. 이산화탄소 발생량은 발효 48시간대에서 민들레, 씀바귀, 제비쑥, 해바라기에서 대조구에 비해 유의적(p<0.05)으로 높게 측정 되었으며, 메탄 발생량도 발효 48시간대에서 민들레, 씀바귀, 제비쑥, 해바라기에서 대조구에 비해 유의적(p<0.05)으로 높게 측정 되었다. 미생물 성장량은 발효 48시간대에서 제비쑥과 해바라기 처리구에서 대조구에 비해 유의적(p<0.05)으로 높게 측정되었다. 발효 48시간대 에서 Acetic acid 생성량이 민들레, 씀바귀, 제비쑥, 해바라기 처리구에서 대조구에 비해 유의적(p<0.05)으로 높았다. 발효 12시간대에서 Propionic acid 생성량은 씀바귀, 제비쑥, 해바라기 처리구에서 대조구에 비해 유의적(p<0.05)으로 높았다. 발효 24시간대에서 A/P ratio는 민들레, 제비쑥, 해바라기 처리구에서 대조구에 비해 유의적(p<0.05)으로 감소하였다. 본 연구의 결과에 의해 국화과 추출물 첨가가 반추위 발효에 부정적인 영향을 미치지 않는 것으로 생각되나 메탄 발생량을 감소시키는데 영향이 없는 것으로 생각된다.