Cs-137, a radioactive isotope of caesium, is a commonly occurring fission product that is generated during the nuclear fission of U-235 and other fissionable isotopes in both nuclear reactors and weapons. Due to its long half-life of about 30 years and propensity to accumulate in sediments and marine organisms, Cs-137 is considered a major radionuclide for environmental radioactivity monitoring. In April 2021, as the Japanese government decided to discharge Fukushima contaminated water into the sea, the monitoring of marine radioactivity in South Korea has become increasingly significant. In this study, as an initial step towards establishing a standardized procedure for analyzing radioactive caesium in seawater, the radioactivity of Cs-137 was analyzed on a 2 L of seawater spiked with 10 Bq of Cs-137 standard solution supplied by KRISS. The seawater was collected from Im-nang Beach, situated at a distance of approximately 2 kilometers from DIRAMS. The radioactivity of Cs-137 in seawater was determined according to the improved AMP procedure presented by M.Aoyama in 2000. The seawater was pretreated using Ammonium Phosphomolybdate (AMP) coprecipitation, which has a high selectivity for caesium (Kd = ~5500), and the activity of Cs-137 was determined by gammaspectroscopy and subsequently corrected via the weight yield. The weight yield of the dried AMP/Cs compound was more than 93%. For the gamma-spectroscopy analysis, the AMP/Cs compound was dissolved in a cylindrical U8 beaker with NaOH to ensure that its shape and volume were consistent with the CRM (KRISS, 221U890-1) used to calibrate the detector. The dissolved compound was then positioned directly onto the detector housing and subjected to a measurement duration of 80,000 seconds utilizing a p-type HPGe (Ortec, GEM60) with a relative efficiency of 54%. The activity of Cs-137 was determined to be 10.81 Bq, confirming the reproducibility of the AMP coprecipitation and weight yield methods. The present experiment was carried out using a 2 L sample, but a large volume of seawater would be required to achieve a sufficient minimum detectable activity (MDA) for Cs-137 in natural seawater. Thus, a standardized procedure for analysis of radioactive caesium in natural seawater will be established through the analysis of a large volume of seawater in future studies.

In this study, in relation to the demolition of the building as a research reactor, in order to establish a basic design for preparation for relocation and installation of the TRIGA Mark-II, the present conditions such as actual measurements and structural safety were investigated, as well as technologies and cases related to the relocation and installation of cultural properties. Based on this, the basic design for the relocation and installation of cultural assets was established by reviewing the disassembly and transport design of the TRIGA Mark-II and the basic plan for the relocation site. Although the structural safety of the current self-weight of the structure is judged to be reasonable, when lifting the structure, it is necessary to consider a method of lifting the foundation by reinforcing the foundation so that the tensile force can be minimized in the structure. As for the technology to be applied before TRIGA Mark-II, the technology before non-transplacement was confirmed as the most reasonable method in terms of preserving the original form, securing safety, and securing economic feasibility. Among the non-replacement technologies, the methods that can be applied before reactor 1 can be largely classified into three types. The three methods to be reviewed can be largely classified into the traditional rail movement method, the movement method using transport equipment, and the crane movement method. Each required period was calculated from the basic design results, and the modular trailer method was judged to be the most efficient. From the basic design results, the required period for each stage according to the mobile construction method was calculated. Depending on the calculation result, the modular trailer method is judged to be the most efficient. However, the final construction method should be selected according to the detailed design results. Overall, the results obtained through this study suggest that it is possible to create a memorial hall without the previous installation of TRIGA Mark-II if the structure foundation is composed independently of the building foundation after conducting a detailed characteristic investigation on the foundation of the TRIGA Mark-II structure.

In concrete structures exposed to chloride environments such as seashore structures, chloride ions penetrate into the concrete. Chlorine ions in concrete react with cement hydrates to form Friedel’s salt and change the microstructure. Changes in the microstructure of concrete affect the mechanical performance, and the effect varies depending on the concentration of chloride ions that have penetrated. However, research on the mechanical performance of concrete by chloride ion penetration is lacking. In this study, the effect of chloride ion penetration on the mechanical performance of dry cask concrete exposed to the marine environment was investigated. The mixture proportion of self-compacting concrete is used to produce concrete specimens. CaCl2 was used to add chlorine ions, and 0, 1, 2, and 4% of the binder in weight were added. To evaluate the mechanical performance of concrete, a compressive strength test, and a splitting tensile strength test were performed. The compressive strength test was conducted through displacement control to obtain a stress-strain curve, and the loading speed was set to 10 με/sec, which is the speed of the quasi-static level. The splitting tensile strength test was performed according to KS F 2423. As a result of the experiment, the compressive strength increased when the chloride ion concentration was 1%, and the compressive strength decreased when the chlorine ion concentration was 4%. The effect of the chloride ion concentration on the peak strain was not shown. In order to present a stress-strain curve model according to the chloride ion concentration, the existing concrete compressive stress-strain models were reviewed, and it was confirmed that the experimental results could be simulated through the Popovics model.

The spent fuel is classified based on the arrangement of fuel rods, which is considered the primary characteristic data for selecting nuclear fuel. The reason for prioritizing the classification by fuel rod arrangement is that it has the greatest physical impact on the production, supply, operation, reactor type, rack size within the containment vessel, and specifications for the basket in the future dry storage system. Additionally, as mentioned earlier, various meanings of nuclear fuel types are distinguished according to the arrangement of fuel rod. The burnup and cooling period ranges are also important factors in the characterization analysis for the selection of spent fuel, the burnup range was set for both low and high burnup ranges and the cooling period is necessary to consider the reliability during handling of nuclear fuel thermal distribution within the storage system

A person who performs or plans to conduct a physical protection inspection as stipulated by the law, the act on physical protection and radiological emergency, should obtain an inspector’s ID card certified and authorized by Nuclear Safety and Security Commission Order No.137 (referred to as Order 137). In addition, according to Order 137, KINAC has been operating some training courses for those with the inspector’s ID card or intending to acquire it. Also, strenuous efforts have been put to incrementally elevate their inspection related expertise. Since Republic of Korea has to import uranium enriched less than 20% in order to manufacture fuels of nuclear reactors in domestic and abroad, the physical protection for categorization III nuclear material in transit is significantly important along with an increase in transport. The expertise of inspectors should be constantly needed to strengthen as the increase in transport leads to an increase in inspection of nuclear material in transit. We have suggested a special way to improve the inspector’s capacities through Virtual Reality technology (VR). A 3-Dimensional virtual space was designed and developed using a 3-axis simulator and VR equipment for practical training. HP’s Reverb G2 product, which was developed in collaboration with VALVE Corporation and MicroSoft, was used as VR equipment, and the 3-axis motion simulator was developed by M-line STUDIO corp. in Korea for the purpose of realizing virtual reality. The training scenarios of transport inspection consist of three parts: preparation at the shipping point, transport in route including stops and handover at the receiving point. At the departure point, scenario of the transport preparation is composed with the contents of checking the transport-related documents which should be carried by shipper and/or carrier during transport and confirming who the shipper and/or carrier is. Second, scenario is designed for inspector to experience how carrier and/or shipper protect the nuclear material during transport or stops for rests or contingency and how they communicate with each other during transport. Lastly, scenario is developed focusing on key check items during handover of responsibilities to the facility operator at the destination. Those training scenarios can be adopted to strengthen the capabilities of those with inspector’s ID card of physical protection in accordance with Order 137 and to help new inspectors acquire inspectionrelated expertise. In addition, they can be used for domestic education to promote understanding of nuclear security, or may be used for education for people overseas for the purpose of export of nuclear facilities.

본 연구는 1959년 일본의 재일조선인 북한송환(북송) 발표 직후인 2월 부터 6월까지 한일 양국의 국회에서는 재일조선인 북송에 대해 어떻게 논의를 전개하였는지 분석하였다. 즉, 본 연구의 질문은 ‘1959년 초반 한국 국회와 일본 국회는 재일조선인 북송 문제에 대해 어떠한 논의를 했는가?’이다. 이에 답하기 위해 본 연구는 한국 국회와 일본 국회의 1959년 회의록을 분석했고 그 결과는 다음과 같다. 우선 한국의 국회는 북한을 주권국가가 아니라고 보며 일본의 재일조선인 북송 계획에 반대 하는 논의를 하였다. 그러나 시간이 지나면서 국회 내의 의견 차이로 한 국 국회가 재일조선인 북송 문제 해결을 위한 구체적이고 본격적인 논의 를 진행하는 것은 어려웠다. 반면 일본의 국회는 한국 정부와의 관계 악 화를 우려해 재일조선인 북송 문제를 한일회담과 구분하여 처리하는 방 안을 논의했다. 또한, 일본 국회는 일본 정부가 북송 문제에 직접 관여하 지 않도록 국제적십자위원회가 재일조선인 북송 문제를 주도하여 해결해 야 한다는 방침을 세우며, 동시에 북송 실행을 위해 북한적십자사와의 회담에서 원만한 해결을 위해 논의를 확장하였다. 그러므로 재일조선인 북송 문제에 대한 1959년 2월부터 6월까지의 한국과 일본의 양국 국회 의 논의를 비교하면, 일본 국회의 논의가 한국의 국회 논의보다 구체적 이고 적극적이었다는 사실을 알 수 있다. 이후 1959년 12월 재일조선인 의 북송은 결국 실행되었다.