The domestic Pressurized Heavy Water Reactor (PWHR) nuclear power plant, Wolsong Unit 1, was permanently shut down on December 24, 2019. However, research on decommissioning has mainly focused on Pressurized Water Reactors (PWRs), with a notable absence of both domestic and international experience in the decommissioning of PHWRs. If proper business management such as radiation safety and waste is not performed, it can lead to increased business risks and costs in decommissioning. Therefore, the assessment of waste volume and cost, which provide fundamental data for the nuclear decommissioning process, is a crucial technical requirement before initiating the actual decommissioning of Wolsong Unit 1. Decommissioning radiation-contaminated structures and facilities presents significant challenges due to high radiation levels, making it difficult for workers to access these areas. Therefore, technology development should precede decommissioning process assessments and safety evaluations, facilitating the derivation of optimal decommissioning procedures and ensuring worker safety while enhancing the efficiency of decommissioning operations. In this study, we have developed a program to estimate decommissioning waste amounts for PHWRs, building upon prior research on PWR decommissioning projects while accounting for the specific design characteristics of PHWRs. To evaluate the amount of radioactive waste generated during decommissioning, we considered the characteristics of radioactive waste, disposal methods, packaging container specifications, and the criteria for the transfer of radioactive waste to disposal operators. Based on the derived algorithm, we conducted a detailed design and implemented the program. The proposed program is based on 3D modeling of the decommissioning components and the calculation of the Work Difficulty Factor (WDF), which is used to determine the time weighting factors for each task. Program users can select the cutting and packaging conditions for decommissioning components, estimate waste amount based on the chosen decommissioning method, and calculate costs using time weighting factors. It can be applied not only to PHWRs, but also to PWRs and non-nuclear fields, providing a flexible tool for optimizing decommissioning process.

With the aging of nuclear power plants (NPPs) in 37 countries around the world, 207 out of 437 NPPs have been permanently shutdown as of August 2022 according to the IAEA. In Korea, the decommissioning of NPPs is emerging as a challenge due to the permanent shutdown of Kori Unit 1 and Wolsong Unit 1. However, there are no cases of decommissioning activities for Heavy Water Reactor (HWR) such as Wolsong Unit 1 although most of the decommissioning technologies for Light Water Reactor (LWR) such as Kori Unit 1 have been developed and there are cases of overseas decommissioning activities. This study shows the development of a decommissioning waste amount/cost/process linkage program for decommissioning Pressurized Heavy Water Reactor (PHWR), i.e. CANDU NPPs. The proposed program is an integrated management program that can derive optimal processes from an economic and safety perspective when decommissioning PHWR based on 3D modeling of the structures and digital mock-up system that links the characteristic data of PHWR, equipment and construction methods. This program can be used to simulate the nuclear decommissioning activities in a virtual space in three dimensions, and to evaluate the decommissioning operation characteristics, waste amount, cost, and exposure dose to worker. In order to verify the results, our methods for calculating optimal decommissioning quantity, which are closely related to radiological impact on workers and cost reduction during decommissioning, were compared with the methods of the foreign specialized institution (NAGRA). The optimal decommissioning quantity can be calculated by classifying the radioactivity level through MCNP modeling of waste, investigating domestic disposal containers, and selecting cutting sizes, so that costs can be reduced according to the final disposal waste reduction. As the target waste to be decommissioning for comparative study with NAGRA, the calandria in PHWR was modeled using MCNP. For packaging waste container, NAGRA selected three (P2A, P3, MOSAIK), and we selected two (P2A, P3) and compared them. It is intended to develop an integrated management program to derive the optimal process for decommissioning PHWR by linking the optimal decommissioning quantity calculation methodology with the detailed studies on exposure dose to worker, decommissioning order, difficulty of work, and cost evaluation. As a result, it is considered that it can be used not only for PHWR but also for other types of NPPs decommissioning in the future to derive optimal results such as worker safety and cost reduction.

This study was conducted to evaluate the efficacy of mulberry leaf mixed diet on larval growth of Protaetia brevitarsis. As a result of adding mulberry leaves to oak fermented sawdust, the survival rate of P. brevitarsis larvae were higher than those of the control when mass rearing larvae. When fed oak fermented sawdust with 5%, 10% and 20% of mulberry leaves, the cumulative proportion of larvae over 2.5g was 93.1% at 65 days, 95.6% at 55 days, and 93.9% at 55 days after rearing at 25±1℃, respectively. Also, heavy metals were not detected in larvae of P. brevitarsis fed on mulberry leaves.

This study was conducted to evaluate the efficacy of mulberry cake mixed diet on larval growth of Protaetia brevitarsis. As a result of adding mulberry cake to oak fermented sawdust and mulberry fermented sawdust, the survival rate of P. brevitarsis larvae were higher than those of the control when mass rearing larvae. When fed oak fermented sawdust with 3, 5% and 10% of mulberry cake, the cumulative proportion of larvae over 2.5g was 92.9% at 65 days, 90.8% at 55 days, and 96.3% at 45 days after rearing at 25±1℃, respectively. When fed mulberry fermented sawdust with 3%, 5% and 10% of mulberry cake, the cumulative proportion of larvae over 2.5g was 86.2% at 85 days, 90.7% at 75 days, and 91.5% at 75 days after rearing at 25±1℃, respectively.

전라북도는 곤충사육농가의 77%인 121농가가 흰점박이꽃무지를 사육하고 있고 농가수의 증가가 예상됨에 따라, 생산단가를 절감시키면서 효율적인 사육을 위해서는 사육환경을 최적으로 유지하는 것이 매우 중요하다. 따라서 본 연구에서는 뽕나무발효톱밥을 이용하여 유충사육밀도에 따른 유충발육상황을 조사하였다. 최적 사육밀도 설정을 위하여 전라북도 사육농가에서 가장 많이 사용하는 20L 크기의 사육 상자에 각각 100, 125, 150, 175, 200마리 흰점박이꽃무지 유충을 넣고 뽕나무발효톱밥을 2/3정도 채운 후 사육하면서 유충무게변화, 생존율 등을 조사하였다. 부화 후 95일 흰점박이꽃무지 유충 생존율은 평균 81%로 사육밀도별 큰 차이가 없었다. 유충 무게는 100마리/20L 사육 시 2.219g로 가장 높게 나타났으며, 사육밀도가 증가함에 따라 감소하는 경향으로 나타났다. 유충 영양성분 조사결과 단백질 52.8g/100g, 지방 11.8g/100g이었으며, 중금속은 검출되지 않았다.

In order to develop the D. adamsi breeding technique that is highly likely to be used as an emotional pet insect, the results of the D. adamsi was collected in the large exhibition Jang Tae-san in Daejeon to the indoor breeding began to spawn after 10 days after the training, the egg laying period was 33.6 days, the average number of spawn per female was 27.7, and the period was 11.8 days. D. adamsi larvae bred with food of oak-boiled molted two times, the duration of 1st larvae development was 11.8 days, 2nd larvae 14.5 days, and the third larvae was 29.4, and the larvae were used to build houses using Masato(soil) and in the pupae, and then in April of the following year. D. adamsi has a characteristic to build a house with fallen leaves and spawn one or two eggs in the fallen leaves, and the results of the spawn mat test using fallen leaves, leaf mold and a sawdust, etc., and the number of spawn was high in the Masato was spread about 3 ~ 5cm, and a fallen leaves on a 10 cm or so, and the growth and survival rate of the larvae were also high. Larvae breeding density was 2 ~ 3 ℓ in the container size to raise the object was normal growth, the higher the density mortality was high and the growth was sluggish. Larvae feeding conditions were normally developed in dry fallen leaves and fermented fallen leaves, compared to the sterile fallen leaves, oak sawdust, sterile fallen leaves and oak sawdust was abnormal, the mortality rate was higher than 50%.

본 연구에서는 유변물성측정기를 이용하여 HPMC 첨가량, 물 양, HPMC 분자량, 셀룰로오스 에테르 치환체 및 치환도가 쌀 반죽의 압축 및 접착 특성에 미치는 영향에 대해 살펴보았다. HPMC 첨가량이 증가함에 따라 접착강도는 꾸준히 증가하였으나, 압축강도는 2% HPMC 첨가량에서 최대 강도를 보였다. HPMC의 분자량이 증가하거나, 물 양이 감소할수록 쌀 반죽의 압축강도 및 접착강도가 증가하는 결과를 보였다. 이들 인자 외에도, 셀룰로오스 에테르의 치환체 및 치환도도 쌀 반죽의 압축강도 및 접착 강도를 결정하는 중요한 인자임을 확인하였다.

This study examined the effect of the molecular weight, substitution degree, and substitution type of cellulose ether on the mechanical properties of dried rice noodles. When increasing the molecular weight of the hydroxypropyl methylcellulose (HPMC), the bending strength of the dried rice noodles also increased. However, the bending strength of the rice noodles with added HPMCs was still lower than that of the wheat noodles. Meanwhile, the bending elongation of the dried rice noodles was higher than that of the wheat noodles and was increased when decreasing the molecular weight of the HPMC. In conclusion, the bending strength and elongation of dried rice noodles is affected by the substitution degree and type of cellulose ether.