According to the nuclear safety act, the enforcement regulations and the notification of the atomic energy commission, a preliminary decommissioning plan must be submitted at all domestic nuclear facilities. In accordance with this preliminary decommissioning plan, it is required to prepare eleven items from the outline of the decommissioning plan of the nuclear facility to the fire protection. Currently, the nuclear fuel cycle facility operated by the Korea Atomic Energy Research Institute (KAERI) consists of a radioactive waste form test facility (RWFTF), a post irradiation examination facility (PIEF), a radioactive waste treatment facility (RWTF), and a radioactive waste storage facility (RWSF). The decommissioning strategies, decommissioning methods and dismantling activities of these nuclear facilities are described in this paper. The scope of decommissioning, the dismantling method, the final conditions of the site, the management of radioactive waste, and the cost of decommissioning are established in the decommissioning strategy. The decommissioning schedule, work order, basic principle and technical feasibility are determined at the method of decommissioning. The disinfection techniques and activity plans for facilities and sites contaminated with radioactive materials are described at the dismantling activity. Therefore, this paper describes the concept of decommissioning of the nuclear fuel cycle facilities and prepares a preliminary decommissioning plan to be prepared afterwards.

A membrane bioreactor by sequentially alternating the inflow and by applying a two-stage coagulation control based on pre-coagulation was evaluated in terms of phosphorus removal efficiency and cost-savings. The MBR consisted of two identical alternative reaction tanks, followed by aerobic, anoxic and membrane tanks, where the wastewater and the internal return sludge alternatively flowed into each alternative reaction tank at every 2 hours. In the batch-operated alternative reaction tank, the initial concentration of nitrate rapidly decreased from 2.3 to 0.4 mg/L for only 20 minutes after stopping the inflow, followed by substantial release of phosphorus up to 4 mg/L under anaerobic condition. Jar test showed that the minimum alum doses to reduce the initial PO4-P below 0.2 mg/L were 2 and 9 mol-Al/mol-P in the wastewater and the activated sludge from the membrane tank, respectively. It implies that a pre-coagulation in influent is more cost-efficient for phosphorus removal than the coagulation in the bioreactor. On the result of NUR test, there were little difference in terms of denitrification rate and contents of readily biodegradable COD between raw wastewater and pre-coagulated wastewater. When adding alum into the aerobic tank, alum doses above 26 mg/L as Al2O3 caused inhibitory effects on ammonia oxidation. Using the two-stage coagulation control based on pre-coagulation, the P concentration in the MBR effluent was kept below 0.2 mg/L with the alum of 2.7 mg/L as Al2O3, which was much lower than 5.1∼7.4 mg/L as Al2O3 required for typical wastewater treatment plants. During the long-term operation of MBR, there was no change of the TMP increase rate before and after alum addition.

Capacitive deionization(CDI) has many advantages over other desalination technologies due to its low energy consumption, less environmental pollution and relative low fouling potential. The objectives of this study are evaluate the performance of CDI which can be used for dissolved salts removal from sewage. To identify ion selectivity of nitrate and phosphate in multi-ionic solutions and adsorption/desorption performance related to applied potential, a series of laboratory scale experiments were conducted using a CDI unit cell with activated carbon electrodes. The CDI process was able to achieve more than 75 % TDS and NO3-, NH4+ removals, while phosphate removal was 60.8 % and is inversely related in initial TDS and H3- concentration. In continuous operation, increasing the inner cell pressure and reduction of TDS removal ability were investigated which are caused by inorganic scaling and biofouling. However a relative mild cleaning solution(5 % of citric acid for calcium scaling and 500 mg/L of NaOCl for organic fouling) restored the electrochemical adsorption capacity of the CDI unit to its initial level.

4가지 서로 다른 소재(대나무, 목재, 피탄, 석탄)로 제조된 10가지 활성탄에 대해서, 30% 알코올모델용액에 용해되어 있는 6가지 휘발성화합물(isoamyl alcohol, hexanal, furfural, ethyl lactate, ethyl octanoate, 2-phenyl ethanol)의 흡착효율을 평가하였다. 이들 6가지 휘발성화합물은 알코올음료에서 종종 발견되며, 농도가 높을 경우에는 숙취의 원인이 될 뿐만이 아니라 위스키나 보드카와 같은 술에서 이취의 원인물질이 되기도 한다. 6가지 휘발성화합물이 용해되어 있는 30% 알코올모델용액 200 mL에 0.2 g의 활성탄을 넣고 16시간 일정한 속도로 교반한 후에 처리된 용액을 2가지 시료처리방법(direct liquid injection and headspace-solid phase microextraction)을 이용 GC분석을 수행하여 활성탄의 제거효율을 구하였다. 활성탄의 제거효율은 휘발성화합물의 종류와 활성탄제조의 소재에 따라 차이가 있었으며, ethy octanoate, 2-phenyl ethanol, hexanal에 대한 제거율은 34-100%로 높은 편이나, isoamyl alcohol, ethyl lactate, furfural의 제거율은 5-13%로 비교적 낮은 편이었다. 활성탄의 종류에 따른 제거율은 대나무활성탄인 A가 isoamly alcohol, hexanal, ethyl lactate, furfural 등 대부분의 휘발성화합물에 대해서 유의적으로 높았으며(p < 0.05), 특히 알코올음료에서 숙취와 이취물질이며 fusel oil의 주성분인 isoamyl alcohol, aldehydes(hexanal, furfural), 2-phenyl ethanol에 대한 흡착효율이 높은 것으로 확인되었다.