Properties of bentonite, mainly used as buffer and/or backfill materials, will evolve with time due to thermo-hydro-mechanical-chemical (THMC) processes, which could deteriorate the long-term integrity of the engineered barrier system. In particular, degradation of the backfill in the evolution processes makes it impossible to sufficiently perform the safety functions assigned to prevent groundwater infiltration and retard radionuclide transport. To phenomenologically understand the performance degradation to be caused by evolution, it is essential to conduct the demonstration test for backfill material under the deep geological disposal environment. Accordingly, in this paper, we suggest types of tests and items to be measured for identifying the performance evolution of backfill for the Deep Geological Repository (DGR) in Korea, based on the review results on the performance assessment methodology conducted for the operating license application in Finland. Some of insights derived from reviewing the Finnish case are as follows: 1) The THMC evolution characteristics of backfill material are mainly originated from hydro-mechanical and/or hydrochemical processes driven by the groundwater behavior. 2) These evolutions could occur immediately upon installation of backfill materials and vary depending on characteristics of backfill and groundwater. 3) Through the demonstration experiments with various scales, the hydro-mechanical evolution (e.g. advection and mechanical erosion) of the backfill due to changes in hydraulic behavior could be identified. 4) The hydro-chemical evolution (e.g. alteration and microbial activity) could be identified by analyzing the fully-saturated backfill after completing the experiment. Given the findings, it is judged that the following studies should be first conducted for the candidate backfill materials of the domestic DGR. a) Lab-scale experiment: Measurement for dry density and swelling pressure due to saturation of various backfill materials, time required to reach full saturation, and change in hydraulic conductivity with injection pressure. b) Pilot-scale experiment: Measurement for the mass loss due to erosion; Investigation on the fracture (piping channel) forming and resealing in the saturation process; Identification of the hydro-mechanical evolution with the test scale. c) Post-experiment dismantling analysis for saturated backfill: Measurement of dry density, and contents of organic and harmful substances; Investigation of water content distribution and homogenization of density differences; Identification of the hydro-chemical evolution with groundwater conditions. The results of this study could be directly used to establishing the experimental plan for verifying performance of backfill materials of DGR in Korea, provided that the domestic data such as facility design and site characteristics (including information on groundwater) are acquired.

In this research, KPS manufactured Full System Decontamination (FSD) equipment, which is consisted of Oxidizing Agent Manufacturing System (OAMS), Chemical Injection System (CIS), RadWaste Treatment System (RWTS), Chemical Waste Decomposition & Treatment System (CWDS) and conducted demonstration test to prepare Decontamination and Decommissioning (D&D) project of Kori nuclear power plant in Korea. Each equipment of FSD was modularized due to the limited size of equipment hatch of Kori nuclear power plant. To simulate the expected circumstances in nuclear power plant such as usage of heater or position of each equipment, additional equipment was used. The chemical concentration and flow rate of process water for FSD were used as mentioned in the previous study by KHNP CRI. FSD was conducted for three cycles and each cycle was consisted of oxidation, reduction, chemical decomposition and purification. Oxidation and reduction process were conducted at 90°C. Chemical decomposition and purification process were conducted at 40°C due to the damage of UV lamp and IX by the heat. Total volume of process water for FSD demonstration test was 2.5 m2. KPS conducted decontamination performance review by calculating thickness reduction and weight loss of installed specimen. Operational review was conducted as if FSD test was conducted in the field based on the result of demonstration test. One of the most prioritized features is the workers’ safety. Also, the appropriate position of equipment needs to be considered to meet the required specification of component.

In the pilot scale test, the two scale-up factors (Electric energy per order EEO, Electric energy per mass EEM) were conducted to design the Chemical Waste Decomposition & Treatment System (CWDS). The CWDS consist of two kind UV lamp reactors to improve the decomposition rate of oxalic acid, which are low pressure amalgam UV lamp and medium pressure UV lamp. The two reactors were connected in series, and the hydrogen peroxide is mixed through a line mixer at the front of the reactor and injected into the reactors. The CWDS was connected with the full system decontamination equipment to purify the residual oxalic acid after chemical decontamination process. The full system decontamination equipment were included Oxidizing Agent Manufacturing System (OAMS), Chemical Injection System (CIS), RadWaste Treatment System (RWTS) to operate the Oxidation/Reduction decontamination process and purify the process water. After decontamination process, the waste water will be cooled down into the 40°C and passed through the UV reactor at 110 gpm with hydrogen peroxide injection. The concentration of waste water is expected oxalic acid 1,700 ~ 2,000 ppm, Iron 5 ~ 20 ppm. As a result of the CBD test in the laboratory with simulated waste liquid, the amount of Low pressure amalgam lamp UV dose required to decompose 95% of oxalic acid in 2 m2 waste water was up to 1,800 mJ/cm2. The amount of medium pressure lamp UV dose was up to 450 mJ/cm2 at the same condition. We conducted demonstration test using 2 m2 waste water after the oxidation/reduction decontamination process, the decomposition rate 95% was obtained by low pressure amalgam UV lamp and medium pressure UV lamp reactor each.

Deep geological disposal (DGD) of spent nuclear fuels (SNF) at 500 m–1 km depth has been the mainly researched as SNF disposal method, but with the recent drilling technology development, interest in deep borehole disposal (DBD) at 5 km depth is increasing. In DBD, up to 40SNF canisters are disposed of in a borehole with a diameter of about 50 cm, and SNF is disposed of at a depth of 2–5 km underground. DBD has the advantage of minimizing the disposal area and safely isolating highlevel waste from the ecosystem. Recently, due to an increasing necessity of developing an efficient alternative disposal system compared to DGD domestically, technological development for DBD has begun. In this paper, the research status of canister operation technology and plans for DBD demonstration tests, which subjects are being studied in the project of developing a safety-enhancing high-efficiency disposal system, are introduced. The canister operation technology for DBD can be divided into connection device development and operation technology. The developing connection device, emplacing and retrieving canisters in borehole, adopted the concept of a wedge thus making replacement equipment at the surface unnecessary. The new connection device has the advantage of being well applied with emplacement facilities only by simple mechanical operation. The technology of operating a connection device in DBD can be divided into drill pipe, coiled tubing, free-drop, and wireline. The drill pipe is a proven method in the oil industry, but requiring huge surface equipment. The coiled tubing method uses a flexible tube and shares disadvantages as the drill pipe. The free-drop is a convenient method of dropping canister into a borehole, but has a weakness in irretrievability in an accident. Finally, the wireline method can be operational on a small scale using hydraulic cranes, but the number of operated canisters at once is limited. The test facility through which the connection device is to be tested consists of dummy canister, borehole, lifting part, monitoring part, and connecting device. The canister weight is determined according to the emplacement operation unit. The lifting part will be composed following wireline consisting of a crane, a wire and a winding system. The monitoring part will consist of an external monitoring system for hoists and trolleys, and an internal monitoring system for the connection device’s location, pressure, and speed. In this project, a demonstration test will be conducted in a borehole with 1km depth, 10 cm diameter provided by KAERI to verify operation in the actual drilling environment after design improvement of the connecting device. If a problem is found through the demonstration test, the problem will be improved, and an improved connection device will be tested to an extended borehole with a 2 km depth, 40 cm diameter.

점착트랩은 특정 광파장에 유인되는 곤충의 반응을 이용하여 비행 곤충의 유살 및 모니터링에 널리 이용되고 있다. 그러나 유색 점착트랩은 해당 색상에 반응을 보이는 모든 곤충을 유인하기 때문에 비표적곤충(Non target insect)이 부착되는 문제가 발생한다. 비표적곤충은 부착면을 차지하여 표적곤충의 유인을 방해하며, 해충밀도 모니터링에 필요한 노력과 시간 소요를 증대시킨다. 본 연구에서는 비표적 곤충과 이물질의 부착을 물리적으로 방지하기 위하여 내경 5mm, 10mm의 방지망을 설치하였을 때, 각 처리에 따른 유입 곤충의 종다양성 지수를 분석하여 방지망의 현장 적용 가능성을 검정하였다. 그 결과 망을 처리하지 않은 트랩과 5mm, 10mm 방지망을 설치한 트랩 간 종다양성 지수에서 유의한 차이를 보이지 않았다. 그러나 포획된 총 종의 수는 망을 처리하지 않은 트랩에서 높게 나타났는데 이는 대형 비표적 곤충의 포획수가 높은 것이 주 요인이었다. 표적 해충인 총채벌레, 가루이 등 미소해충의 유입 빈도 또한 무처리, 5mm, 10mm 간에 유의한 차이를 보이지 않아 방지망의 설치가 표적곤충인 미소해충의 유입에 악영향이 없으며, 5mm 망을 적용하여도 무방하다는 결과를 얻었다.

Piezoelectric harvester for road power generation was installed on test roads owned by Korea Highway Corporation. 24 harvesters were installed on the concrete pavement and the remaining 12 harvesters were installed on the asphalt pavement. After installation, power generation performance and environmental tests were carried out with three types of vehicles: compact / passenger cars / trucks. The running speed of the vehicle was 30 km/h, 60km/h, 90 km/h. The test results show that the larger the weight of the vehicle, the higher the power generation, the concrete road than the asphalt road, and the exposed type rather than the buried type. The generation amount according to the depth of buried was at least 2.2 times at the depth of 1cm than 5cm depth. When the delegator lighting test was performed using 12 harvesters, it was possible to light up more than 20 seconds in one vehicle due to the improvement of the charging circuit. In addition, the wireless communication module driving test enabled temperature sensing and data transmission for 25 seconds. In addition, there was no breakage of the pavement when driving more than 180 times, and the generation amount was maintained more than 90%. However, Test for the durability of the pavement and the self-durability of the harvester is required more than 180 times of vehicle driving conditions and required more than minimum of 6-12 months of long-term monitoring.

This paper describes the Bayesian and non-Bayesian approach for reliability demonstration test based on the samples from a finite population. The Bayesian approach involves the technical method about how to combine the prior distribution and the likelihood function to produce the posterior distribution. In this paper, the hypergeometric distribution is adopted as a likelihood function for a finite population. The conjugacy of the beta-binomial distribution and the hypergeometric distribution is shown and is used to make a decision about whether to accept or reject the finite population. The predictive distribution of the beta-binomial distribution is shown and will be used for the reliability demonstration test. A numerical example is also given.

This paper describes the Bayesian approach for reliability demonstration test based on the sequential samples from the one-shot devices. The Bayesian approach involves the technical method about how to combine the prior distribution and the likelihood function to produce the posterior distribution. In this paper, the binomial distribution is adopted as a likelihood function for the one-shot devices. The relationship between the beta-binomial distribution and the Polya’s urn model is explained and is used to make a decision about whether to accept or reject the population of the one-shot devices by one by one then in terms of the faulty goods. A numerical example is also given.

This paper describes the Bayesian approach for reliability demonstration test based on the samples from a finite population. The Bayesian approach involves the technical method about how to combine the prior distribution and the likelihood function to pro

We want to accept or reject a finite population with reliability demonstration test. In this paper, we will describe Bayesian approaches for the reliability demonstration test based on the samples from a finite population. The Bayesian method is an approach that prior distribution and likelihood function combine to from posterior distribution. When we select somethings in a samples, we consider hypergeometric distribution. In this paper, we will explain the conjugacy of the beta-binomial distribution and hypergeometric distribution. The purpose of this paper is to make a decision between accept and reject in a finite population based on the conjugacy of the beta-binomial distribution.

According to a NASA Goddard Institute for Space Studies report, temperatures have risen by approximately 1 °C so far, based on temperatures recorded in 1880. The 2003 heatwave in Europe affected approximately 35,000 people across Europe. In this study, a cooling fog, which is used in smart cities, was designed to efficiently reduce the temperature during a heatwave and its pilot test results were interpreted. A model experiment of the cooling fog was conducted using a chamber, in which nano mist spray instruments and spray nozzles were installed. The designed cooling fog chamber model showed a temperature reduction of up to 13.8 °C for artificial pavement and up to 8.0 °C for green surfaces. However, this model was limited by constant wind speed in the experiment. Moreover, if the cooling fog is used when the wind speed is more than 3m/s in the active green zone, the temperature reduction felt by humans is expected to be even greater. As a second study, the effect of cooling fog on temperature reduction was analyzed by installing a pilot test inside the Land Housing Institute (LHI). The data gathered in this research can be useful for the study of heat reduction techniques in urban areas.