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.

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 permanent shutdown of Wolseong 1, PHWR (Pressurized Heavy Water Reactor) was decided. Accordingly, there is need for C-14 treatment technology to spent resin generated by PHWR in classified Medium Level Radioactive Waste by C-14 specific activity. However, spent resin by PHWR is mixed and stored with activated carbon and zeolite (mixture), not a single storage, and separation from the mixture must be carried out in advance for C-14 treatment in the spent resin. This study developed a C-14 treatment facility that combined with the technology of separating spent resin from spent resin mixture by PHWR NPP and the technology of C-14 treatment for disposal. The C-14 treatment facility consists of spent resin separation (Part 1) and treatment of separated spent resin. (Part 2) Part 1 is applied with a process of separating the mixed and stored spent resin from the spent resin mixture by applying a drum screen method. In the case of Part 2, spent resin treatment process for desorbing and collecting C-14 nuclides in the separated spent resin using microwave reactor was applied. Except for the adsorbent used to collect C-14 detached in the process of separating and treating spent resin, no additional material is introduced into the facility, and thus secondary waste is significantly reduced. In addition, pollution prevention banks at the bottom of the facility and a sealed automated circulation system were applied to prevent unexpected leakage and diffusion of radioactive materials and ensure stability of workers. Currently, the C-14 treatment facility has been verified for spent resin separation and spent resin treatment using simulated spent resin mixture, and the facility will be demonstrated and verified for field applicability. According to derived results, it is believed that it will be possible to apply the C-14 treatment facility when decommissioning of PHWR.

This study was conducted to investigate the effect of cold plasma combined with UV-C irradiation against Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes on lettuce. E. coli O157:H7, S. Typhimurium, and L. monocytogenes, corresponding to approximately 5.82, 5.09, 5.65 log CFU/ g, were inoculated on lettuce, respectively. Then, the lettuce was treated with cold plasma, UV-C and combination (cold plasma + UV-C), respectively. The treated lettuce was stored for 9 days at 4oC for microbiological analysis and sensory evaluation. Cold plasma reduced the populations of E. coli O157:H7, S. Typhimurium, and L. monocytogenes by 0.26, 0.65, and 0.93 log CFU/g, respectively. Each microorganism were reduced by 0.87, 0.88, and 1.14 log CFU/ g after UV-C treatment. And, the combined treatment that was treated by cold plasma after UV-C treatment reduced the populations of inoculated microorganisms by 1.44, 2.70, 1.62 log CFU/g, respectively. The all treatment significantly (p < 0.05) reduced the populations of all inoculated bacteria compared to untreated lettuce. UV-C combined with cold plasma was the most effective for reducing the pathogenic bacteria on lettuce, by showing log-reductions of ≥ 2.0 log CFU/g. All treatment was not significantly different until 6 day storage compared to control group in terms of appearance, texture and overall acceptability. Therefore, the combined treatment will be an effective intervention method to control the bacteria on lettuce.

본 연구에서는 열전소자와 플라즈마 장치를 삽입하여 제작된 컨테이너와 기존의 사용되고 있는 스티로폼(EPS)박스에 소고기를 저장하면서 저장 중 품질특성을 조사하였다. 온도변화 측정 결과 저장기간 동안 TCS-1 컨테이너가 2℃ 이하로 온도유지가 잘 되는 것으로 측정되었다. EPS박스는 저장 3일 이후 소고기가 부패되어 더 이상 실험이 불가능 하였다. 소고기의 신선도를 나타내는 휘발성염기질소(VBN)과 지방산패도(TBA)값의 측정 결과, 저장 7일째 TCS-1의 VBN은 7.72 mg%, TBA는 0.52 mgMA/kg, TCS-2의 VBN 값은 9.20 mg%, TBA는 0.91 mgMA/kg로 측정되어 TCS-1이 TCS-2 보다 유의적으로 적은 증가율을 나타내어 소고기의 신선도를 더 잘 유지하는 것으로 판단되었다. 미생물 변화는 저장 7일 TCS-1은 4.62 log CFU/g, TCS-2는 7.09 log CFU/g으로 측정되어 TCS-1이 유의적으로 미생물 증식 억제에 효과적인 것으로 나타났다. 기호도 조사 또한 저장 7일째 TEU-1은 모든 항목에서 6.5점 이상의 평가를 받았으나 TCS-2는 4.1 이하의 평가를 받아 소고기의 상품성이 상실된 것으로 판단되었다. 모든 분석항목에서 TCS-1이 TCS-2보다 소고기 신선도 유지에 효과적인 것으로 판단되었다.

For the distribution of fresh produce, the thermoelectric cooling system combined with thermo electric materials (TEM) and phase change material (PCM) was studied. The PCM used this study was produced by in-situ polymerization technology which referred microencapsulation of hydrocarbon (n-tetradecane and n-hexadecane). In this study, quality characteristics of bell peppers in thermoelectric cooling system combined with TEM and PCM were analyzed and control was placed in an EPS (expanded polystyrene) box. As a result of quality characteristics analysis, weight of bell peppers decreased and moisture content of bell peppers was 90.96~94.43% during storage. Vitamin C content of bell pepper decreased during storage and reduction ratio of control was higher than that of BPT-5 treatment(bell pepper in thermoelectric cooling system with PCM which is kept the temperature at 5℃). The result of color value, on 21 day, ΔE value of BPT-5 treatment was 5.05 while that of control was 41.8. On 21 day, total bacteria count of BPT-5 treated bell pepper shown less than that of control. In conclusion, it suggested that the thermoelectric cooling system combined with PCM improved quality of fresh produce during transportation and storage.

The efficacy of an experimentally designed cold chain container and a currently used styrofoam container was investigated with respect to important factors affecting the quality of fresh beef during storage under different conditions. The temperature in the TEPP-1 container was maintained at 5℃ using a phase change material (PCM) during transport and delivery. During storage in the TEPP-1 container, no significant difference was observed in pH of beef, but color decreased slightly, which does not affect the desire to purchase. After storage for 7 days, the rate of VBN and TBA in the TEPP-1 container, was lower than that in the TEPP-2 container. Drip loss was lower in the TEPP-1 container (0.87%) than in the TEPP-2 container (1.78%). No significant changes were observed in microbal count until 4 days in either of the containers, but after storage for 7 days, the count increased significantly. Microbial count in TEPP-1 was 6.65 log CFU/mL and that in TEPP-2 was 7.62 log CFU/mL. The results of sensory evaluations indicated that the overall acceptability of beef after storage for 7 days was better in the TEPP-1 container than in the TEPP-2 container. The EPS container was inferior in comparison with TEPP-1 and TEPP-2. It was impossible to continue the experiment using the EPS container after 3 days. These results suggest that the experimentally designed TEPP-1 container can be used for beef transport and delivery for 7 days without significantly affecting the quality of beef.

This study was conducted to assess the possibility of preserving frozen vegetables (Aster scaber, soybean sprouts, Chinese cabbage, green pumpkin, and Welsh onion) for a long period and of using them after such storage by measuring changes in quality due to their preservation. Various freshly harvested vegetables were blanched under optimal conditions (that were determined in a preliminary experiment), quick-frozen at –40℃ for 24 h, and stored at –20℃. The change in the chromaticity of the frozen A. scaber, soybean sprouts, Chinese cabbage, green pumpkin, and Welsh onion did not vary. The hardness of the frozen A. scaber, green pumpkin, Chinese cabbage and Welsh onion did not change during the preservation period, whereas the hardness of the cotyledon and hypocotyl of the soybean sprouts significantly increased on the sixth month of their storage. The total bacterial counts of the A. scaber during the preservation period remained constant at 103 CFU/g, whereas those of soybean sprouts, Chinese cabbage, green pumpkin, and Welsh onion decreased slightly to 102 CFU/g. Coliform was not detected in any of the samples. The sensory evaluation showed that the preservation period that was used in this study did not significantly affect the marketability of the frozen vegetables. Therefore, it was considered that A. scaber, soybean sprouts, Chinese cabbage, green pumpkin, and Welsh onion can be safely preserved by freeze-storing them for up to 12 months.

The effects of the initial storage temperature and the PA film packaging on the extension of the shelf-life and the improvement of the postharvest storage quality of muskmelons were studied during their storage. Their storage quality was tested as follows: PA-film-wrapped muskmelons, stored at 2℃ or 7℃ for 30 days after their harvest, were kept at 10℃ for 27 days (total: 57 days). On the fifth day of storage at 10℃ (35th day overall), the weight loss reached 6.4% in the 7-control. However, the 2-PA showed the smallest loss of 2.2%. The soluble solids content and the acidity that were measured before the storage were 10.8 °brix and 0.26% in all the groups. After 27 days of storage at 10℃ (on the 57th day overall), the values were highest in the 2-PA group with 9.7 °brix and 0.15%, respectively. Microorganisms were not detected at first; but on the fifth day of storage at 10℃ (35th day overall), their values were 3.87 and 2.68 log CFU/g in the seven-control and the 2-PA, respectively. In other words, the 2-PA was found to be more effective in inhibiting microbial proliferation. In relation to sensory properties such as appearance, flavor, sweetness and chewiness, the 2-PA was superior to the other groups and was found to be most effective in improving the storability of muskmelons. In conclusion, it was found that low-temperature injury and fast storage quality deterioration did not occur in film-wrapped muskmelons that were stored at 2℃ for 30 days after they were harvested.