KHNP is conducting research to decommission Wolsong Unit 1 Calandria. Establishment of preparation and dismantlement processes, conceptual design of equipment and temporary radiation protection facilities, and waste management are being established. In particular, the ALARA plan is to be established by performing exposure dose evaluation for workers. This study aims to deal with the methodology of evaluating exposure dose based on the calandria dismantling process. The preparation process consists of bringing in and installing tooling and devices, and removing interference facilities to secure work space. The main source term for the preparation process is the calandria structure itself and crud of feeders. In the case of the dismantlement process, a structure with a shape that changes according to the process was modeled as a radiation source. It is intended to estimate the exposure dose by selecting the number of workers, time, and location required for each process in the radiation field evaluated according to the preparation and dismantlement process. In addition, it is also conducting an evaluation of the impact on dust generated by cutting operations and the human impact of C-14, H-3, which are specialized nuclides for heavy water reactors. KHNP is conducting an exposure dose evaluation based on a process based on the preparation and dismantlement process for decommissioning Calandria through computation code analysis. If additional worker protection measures are deemed necessary through dose evaluation according to this methodology, the process is improved to prepare for the dismantling of worker safety priorities.

This study was aimed to isolate bacterial inoculants producing chitinase and evaluate their application effects on corn silage. Four corn silages were collected from four beef cattle farms to serve as the sources of bacterial inoculants. All isolates were tested against Fusarium graminearum head blight fungus MHGNU F132 to confirm their antifungal effects. The enzyme activities (carboxylesterase and chitinase) were also measured to isolate the bacterial inoculant. Based on the activities of anti-head blight fungus, carboxylesterase, and chitinase, L. buchneri L11-1 and L. paracasei L9-3 were subjected to silage production. Corn forage (cv. Gwangpyeongok) was ensiled into a 10 L mini silo (5 kg) in quadruplication for 90 days. A 2 × 2 factorial design consists of F. graminearum contamination at 1.0104 cfu/g (UCT (no contamination) vs. CT (contamination)) and inoculant application at 2.1 × 105 cfu/g (CON (no inoculant) vs. INO (inoculant)) used in this study. After 90 days of ensiling, the contents of CP, NDF, and ADF increased (p<0.05) by F. graminearum contamination, while IVDMD, acetate, and aerobic stability decreased (p<0.05). Meanwhile, aerobic stability decreased (p<0.05) by inoculant application. There were interaction effects (p<0.05) on IVNDFD, NH3-N, LAB, and yeast, which were highest in UCT-INO, UCT-CON, CT-INO, and CT-CON & INO, respectively. In conclusion, this study found that mold contamination could negatively impact silage quality, but isolated inoculants had limited effects on IVNDFD and yeast.

Kori unit 1, the first PWR (Pressurized Water Reactor) in Korea, was permanent shut down in 2017. In Korea, according to the Nuclear Safety Act, the FDP (Final Decommissioning Plan) must be submitted within 5 years of permanent shutdown. According to NSSC Notice, the types, volumes, and radioactivity of solid radioactive wastes should be included in FDP chapter 9, Radioactive Waste Management, Therefore, in this study, the types depending on generation characteristics and radiological characterization methods and process of solid radioactive waste were analyzed. Solid radioactive waste depending on the characteristics of the generation was classified into reactor vessel and reactor vessel internal, large components, small metals, spent nuclear fuel storage racks, insulation, wires, concrete debris, scattering concrete, asbestos, mixed waste, soil, spent resins and filters, and dry active waste. Radiological characterization of solid radioactive waste is performed to determine the characteristics of radioactive contamination, including the type and concentration of radionuclides. It is necessary to ensure the representativeness of the sample for the structures, systems and components to be evaluated and to apply appropriate evaluation methods and procedures according to the structure, material and type of contamination. Therefore, the radiological characterization is divided into concrete and structures, systems and components, and reactor vessel, reactor vessel internal and bioshield concrete. In this study, the types depending on generation characteristics and radiological characterization methods and process of solid radioactive waste were analyzed. The results of this study can be used as a basis for the preparation of the FDP for the Kori unit 1.

According to IAEA PRIS, there is no record of dismantling commercial heavy water reactors among 57 heavy water reactors around the world. In Canada, which has the largest number of heavy water reactors, three of the 22 commercial heavy water reactors with more than 500 MW are permanently suspended, Gentilly unit 2 (2012), Pickering unit 2 (2007), and Pickering unit 3 (2008), all of which chose a delayed decommissioning strategy. On the other hand, Wolsong unit 1, which will be the world’s first heavy water reactor to be dismantled commercially, will be immediately carried out as a decommissioning strategy. KHNP has established various cooperation systems with advanced companies and international organizations related to overseas NPP decommission and is actively exchanging technologies. Among them, the most important focus is on research cooperation related to COG (CANDU owners Group). The first case is a joint study on Conceptual Calandria Segmentation. Four areas of process, waste management, ALARA, and cost for decommissioning reactors to be submitted to Canadian regulators for approval of Pickering and Gentilly-2’s preliminary decommissioning plan have been evaluated, and research on Wolsong unit 1 is currently underway. The second case is Decommissioning and long-term waste management R&D. Although the technical maturity is low, it studies the common interests of member companies in the decommissioning of heavy water reactor power generation companies and long-term waste management. Robotics for dismantling high-radiation structures, C- 14, H-3 measurement and removal methods, and concrete decontamination technology, which are characterized by heavy water, are being actively studied. KHNP is strengthening international cooperation with COG to prepare for the successful decommissioning of Wolsong unit 1. Based on previous studies by Pickering and Gentilly-2, an evaluation of the decommissioning of Wolsong unit 1 reactor is being conducted. In addition, it is preparing for decommissioning through experience analysis of the pressure tube replacement project.

Wolsong unit 1, the first PHWR (Pressurized Heavy Water Reactor) in Korea, was permanent shut down in 2019. In Korea, according to the Nuclear Safety Act, the FDP (Final Decommissioning Plan) must be submitted within 5 years of permanent shutdown. According to NSSC Notice, the types, volumes, and radioactivity of solid radioactive wastes should be included in FDP chapter 9, Radioactive Waste Management, Therefore, in this study, activation assessment and waste classification of the End shield, which is a major activation component, were conducted. MCNP and ORIGEN-S computer codes were used for the activation assessment of the End shield. Radioactive waste levels were classified according to the cooling period of 0 to 20 years in consideration of the actual start of decommissioning. The End shield consists of Lattice tube, Shielding ball, Sleeve insert, Calandria tube shielding sleeve, and Embedment Ring. Among the components composed for each fuel channel, the neutron flux was calculated for the components whose level was not predicted by preliminary activation assessment, by dividing them into three channel regions: central channel, inter channel, and outer channel. In the case of the shielding ball, the neutron flux was calculated in the area up to 10 cm close to the core and other parts to check the decrease in neutron flux with the distance from the core. The neutron flux calculations showed that the highest neutron flux was calculated at the Sleeve insert, the component closest to the fuel channel. It was found that the neutron flux decreased by about 1/10 to 1/20 as the distance from the core increased by 20 cm. The outer channel was found to have about 30% of the neutron flux of the center channel. It was found that no change in radioactive waste level due to decay occurred during the 0 to 20 years cooling period. In this study, activation assessment and waste classification of End Shield in Wolsong unit 1 was conducted. The results of this study can be used as a basis for the preparation of the FDP for the Wolsong unit 1.

The kidney is a highly complex organ, and acute or chronic renal diseases can occur with various complications such as diabetes and hypertension. So far, no target specific treatment is available in acute or chronic renal failure, necessitating the development of alternative therapeutic strategy. Recent experimental findings suggest that the renal function and structure can be restored after being treated with various sources of stem/progenitor cells. In this review, we discuss up-to-date findings of the potential of renal progenitor/stem cells in alleviating renal injuries with a focus on preclinical studies. We also review cellular mechanisms underlying the therapeutic function of these cells.

Acute kidney injury (AKI) is a disorder that is manifested by a sudden decrease of renal function within several hours, and AKI remains a significant cause that can lead to increasing morbidity and mortality. Although AKI has been extensively studies in animal models, translating the results from animal studies into clinical use has not been successful due to various factors including basal etiology of kidney deficiency and comorbidities and the complexity of this pathology. As a golden parameter, measuring serum creatinine (SCr) and blood urea nitrogen (BUN) has been conventionally used for determining the renal function, however, these biomarkers has been regarded suboptimal to identify renal injuries in early stages. In this study, we attempted to screen other serum biomarkers in early AKI event using cynomolgus monkeys. Two male monkeys, aged 60 months, were subjected to ischemic injury by unilateral clamping of renal pedicles for forty five minutes and then subsequently reperfused; the unclamped kidney was regarded as non-injured controls. Compared with control kidneys, we have found that the concentration of several inflammatory proteins including MCP1, TGFα, GSTα, were higher in the renal vein of injured kidney compared with control side after 24 and 48 hours of AKI. However, changes of serum level of KIM-1, which is one of the most-widely studied marker in rodent studies, were not different after AKI. Our results provide an useful information while developing a novel marker in AKI.

본 연구에서는 김치 제조시 철저한 재료 세척의 필요성을 확인하고, 더불어 비가열 식품인 김치의 위생 안전성 실태를 파악하여 효율적 미생물 저감화 방안을 마련하고자 국내에서 유통되는 김치 원·부재료 200건의 세척 전과 후의 비교분석과 시판 김치 100건에 대하여 미생물 분석을 실시하였다. 김치 원·부재료 및 완제품에 대하여 일반 세균수, 대장균 및 대장균군을 모니터링 하였으며, 병원성 미생물 9종(Bacillus cereus, Clostridium perfringens 정성·정 량, Staphylococcus aureus, Enterohemorrhagic Escherichia coli, Campylobacter jejuni/coli, Yersinia enterocolitica, Salmonella spp., Vibrio parahaemolyticus, Listeria monocytogenes 정성)을 분석 하였다. 모니터링 결과, 김치 원· 부재료 및 완제품에서 일반세균은 1.4~9.0 log CFU/g 수준 으로 확인되었으며, 원·부재료 중 생강에서 8.8 log CFU/g, 완제품 중 총각김치에서 9.0 log CFU/g으로 일반세균이 가장 높게 나타났다. 대장균군은 0.5~7.3 log CFU/g으로 확 인되었으며, 생강에서 7.3 log CFU/g으로 가장 높게 나타 났고, 병원성 미생물 9종의 분석결과, Bacillus cereus를 제 외한 나머지 8종의 식중독균은 모든 시료에서 검출되지 않았다. 김치 제조 시 사용되는 김치 원·부재료들의 세척 공정 후 미생물 수는 일반세균수 0.2~3.2 log CFU/g, 대장 균군 0.3~2.7 log CFU/g, Bacillus cereus 1.0~3.9 log CFU/g 감소하였다. 따라서, 김치 원·부재료의 세척 공정으로 미생물 오염도를 감소 시켰으며, 이 결과를 통하여 김치 완 제품의 위생 및 저장성 증진에 기여 할 수 있을 것으로 확인되었다.

본 연구는 시설딸기 ‘매향’의 생육과 런너 생산을 위한 생장조절제의 처리방법과 농도의 효과를 조사하기 위해 수행되었다. 딸기 묘를 2016년 2월 22일에 상업용 혼합 상토(토실이)를 이용하여 딸기 재배 포트(64×27×18cm)에 정식하였다. 생장조절제인 6-benzylaminopurine을 이용하여, 정식 후 3주째에 농도를 900, 1,200, 1,500mg·L-1로 제조하여 식물체당 50mL씩 각각 엽면살포와 배지관주하였다. 양액의 공급은 EC 수준을 0.65dS·m-1로 맞추어 뿌리 활착을 위해 충분히 공급하였다. 뿌리 활착 후에는 배양액의 1회 공급량을 딸기 재배 포트 당 450mL로 하루 2회(10분)씩 공급하였다. ‘매향’ 딸기 모주의 초장과 크라운 직경은 유의적인 차이를 나타내지 않았다. 근장, 1차 근수, 엽장, 엽폭, 엽면적, 지상부와 지하부의 생체중과 건물중과 같은 다른 생육 특성은 생장조절제를 처리 하지 않은 대조구에서 유의적으로 높은 값을 나타냈다. 그리고, 딸기의 SPAD 값은 900mg·L-1의 배지관주에서 44.2로 가장 높은 값을 나타냈다. 엽면살포 처리는 배지 관주 처리보다 런너 생산에 효과적이었으며, 900과 1,500mg·L-1 처리에서 런너 수가 가장 많았다. 반면에, 자묘 수는 엽면살포보다 배지관주에서 효과적이었다. 결과적으로, 시설딸기 ‘매향’의 생육과 런너 수는 900mg·L-1의 농도로 엽면살포한 처리에서 가장 효과적인 것으로 나타났다.

본 논문에서는 노심용융사고 시 관통노즐이 제거된 원자로용기 하부헤드의 구조 건전성 평가를 수행하였다. 열응력, 노심용융물의 질량 그리고 내압조건의 해석결과를 고려할 때, 하부헤드의 열응력에 의한 영향이 가장 크게 나타났다. 손상 가능성은 파손기준에 따라 평가하였으며, 등가소성변형률이 임계변형률 파손기준보다 낮은 수준으로 평가되었다. 열-구조물 연성해석 결과 하부헤드의 두께 중간층에서 항복강도보다 낮은 응력이 발생한 탄성영역 구간을 확인하였다. 내압이 커지면서 탄성영역 범위가 점차 좁아지면서 탄성영역이 내벽으로 이동하는 결과를 확인하였고, 노심용융사고 시 구조적 건전성을 만족하는 것으로 평가되었다.

Most patients with chronic low back pain experience functional disability of trunk muscle, and limitations in physical activity. While there are many types of exercise programs available, in recent years sling exercise has been emerging as the exercise program for spinal stabilization. It has been supported by a great amount of research with positive findings on its effectiveness. This research studies the effects of bridging exercise, conducted on a sling, on pain level and trunk muscle activation in supine, sidelying, and prone positions during a 4 weeks period. 10 healthy people(normal group, n=10) and 28 patients with low back pain participated in this study. 28 patients were divided into two groups; one group participated in exercise with the sling(experimental group, n=14) and the other group exercised without the sling(control group, n=14). They were asked to use the Numerical Rating Scale(NRS) to answer to the level of their pain they felt (no pain: 0 point, severe pain: 10 points). During sling bridging exercises, the muscle activity level in each muscle measured in each position was standardized as three seconds of EMG signals during five seconds MVIC. In conclusion, the experimental group with four weeks of sling bridging exercise experienced a statistically significant reduction in the pain level(p<.05) and increase in the muscle activities of erector spinae when in supine position, internal oblique when in sidelying position, and rectus abdominis in prone position(p<.05). Regular sling bridging exercise reduces the low back pain and enhances other trunk muscle activation, thereby positively affect spinal stabilization.