Molten salt reactor (MSR) has a unique characteristic using liquid fuel and/or coolant salt among six type of GEN IV reactors. Liquid fuels and on-site processing are fundamentally different from a solid fuel reactor where separate facilities produce the fresh solid fuel and process the Spent Nuclear Fuel. Because the choice of fuel cycle affects the safeguards and non-proliferation characteristics of the reactor system, different MSR concepts may have different proliferation resistance and physical protection characteristics. For example, MSR design variants that use solid fuel but are cooled with liquid salts such as FHR are very close to the Very High Temperature Reactor design concept. The composition of various fuel salts is a representative factor that makes it difficult to generalize the PRPP evaluation principle of MSR. In addition, the flow of molten salts containing fissile materials is also complex depending on the design of the reactor. The path through which radioactive materials travel not only inside the reactor but also to nuclear fuel cycle facilities can act as a difficult factor in measuring nuclear materials. As a further complication, some of the plants include fuel salt drain tanks intended to provide decay heat removal while others are designed to provide decay heat removal while the salt is maintained within the reactor vessel. Some lessons learned from the prior molten salt breeder reactor program are reflected in all of the new designs. Interior reflectors/shielding are frequently employed to reduce the radiation damage to the reactor vessel, and fuel salt chemistry control is employed to substantially limit oxidizing the container alloy constituents. However, even with the vessel interior shielding, the containment environment around both solid and liquid fueled MSRs during operation is likely to have substantially higher dose rates than at LWRs due to the fission process and fission products in the case of circulating liquid fueled reactors, and the shortlived activation products of fluorine (16N, 20F, and 19O) in the case of FHRs. Consequentially due to insufficient shielding from the coolant and the vessel wall, MSR containments will be remote access only for liquid fueled systems and remote access only during operation for FHRs.

The License on Technology Export of Nuclear Plant is a system that permits the export of strategic technologies for large-scale NPP projects collectively during the project period. So, an issuance of the export license could be omitted for each transfer of technology, but Post Strategic Items Confirmation must be performed before the transfer as a follow-up obligation. Sometimes, transfers of technology have been urgently required during the project. As Post Strategic Items Confirmation process takes up to 15 working days, it may be difficult to respond to urgent situations timely, which may cause setbacks on the project. Therefore, Urgent Technology Transfer System, which allows to transfer technology without prior Post Strategic Items Confirmation, was established to reduce a burden on licensee and improve the efficiency of regulation. This system applies only to the License on Technology Export of Nuclear Plant. In other words, the technology transferred through Urgent Technology Transfer System (hereinafter referred as Urgent Transfer Technology) does not pose any problem with regard to export control because it is already licensed. In addition, the Urgent Transfer Technology should be considered as a strategic technology until Post Strategic Items Confirmation, which means that the Urgent Transfer Technology is more strictly controlled than the generally transferred technology. Also, the Urgent Technology Transfer System does not apply to intangible technology transfers such as technical support through personnel dispatch. The system could be only used in specific conditions which are stipulated for each licensed project in advance in order to prevent indiscriminate abuse of the system by licensee. Licensees are required to report quarterly the stipulated condition corresponding to each Urgent Technology Transfer case, and it would be checked through post-site inspection whether the actual reason for the transfer meets the consulted condition. Moreover, the deadline of application on Post Strategic Items Confirmation after the Urgent Technology Transfer is stipulated for licensee so as not to omit the classification procedure. This Urgent Technology Transfer System does not apply to dual-use items. If the Urgent Transfer Technology is classified as a non-Trigger List Item through the Post Strategic Items Confirmation, it is outside the scope of the NSSC’s export license. In this case, the technology may be subject to an export license of the Ministry of Trade, Industry and Energy (MOTIE). However, if the technology is classified to be a dual-use item after Urgent Technology Transfer, it may result in unauthorized transfer because it has already been transferred. Licensee must apply to classification of MOTIE before Urgent Technology Transfer if the technology being transferred may be related with Dual-use Items. It is easy for licensee to overlook due to the low awareness about this system. Therefore, outreach activities are necessary to raise licensee’s awareness by explaining the Urgent Technology Transfer System and current issues in detail. Consultation with MOTIE may be needed for the improvement on issues.

Investigating major trading partners and items with North Korea is informative in terms that it can predict the path through which North Korea’s strategic items will transfer to non-nuclear-weapon states when North Korea denuclearizes. By analyzing North Korea’s trading partners and the items, it is possible to identify the relevant countries through which items arrive from the first importing country to the end-user in the process of exporting items and to predict the way how North Korea disguise or conceal their strategic items among general items during normal export procedures. As of 2020, North Korea’s major trading partners are China, Russia, Vietnam, India, Nigeria, and Switzerland. Compared to 2019, Mozambique, Tanzania, Ghana, and Thailand entered the top 10, while Brazil, Bangladesh, Pakistan, and South Africa pushed out of the top 10. North Korea’s trade dependence on China accounts for 88.2%, making it the largest trading partner for years, and it shows that North Korea is mainly conducting trade with Asian and African countries. North Korea’s most important export items are mineral products (HS 25-27) and steel & metal products (HS 72-83) and the most significant import items are mineral products (HS 25-27) and oils & fats & prepared foods (HS 15-24). In 2017, due to UN Security Council sanctions for North Korea’s international ballistic missile (ICBM) test-fire, North Korea’s exports from 3 billion dollars fell by 90% to less than 300 million dollars. This is the result of most of North Korea’s major export items included in the export ban, and changes have occurred in its export items. In 2020, export fell to less than 100 million dollars due to border lockdown measures to prevent the spread of COVID-19, which also affected the change of North Korea’s major export items. Although North Korea does not officially publish its foreign trade statistics, in order to review North Korea’s trade information, KOTRA statistics are utilized. KOTRA statistics provide only two digits of HS code number, so it is challenging to identify detailed item classification. Moreover, these statistics are based on the export amount, so it is difficult to determine the exact quantity of export items. It is expected that information on North Korean trading partners and items will be used to predict potential transferable export methods of North Korea’s strategic items when North Korea denuclearizes.

In the previous study, the types of North Korea’s strategic items, foreign trading partners, and export items were investigated. From North Korea’s typical trade paths, it is possible to predict the paths through which North Korea’s strategic items are illegally exported upon denuclearization. Trading partners of North Korea are the potential importing countries or end-users of strategic items, which can be disguised or concealed as if it is general export items during typical export procedures. So, in this study, transfer paths of North Korea’s export items are examined by utilizing KOTRA statistics, including item type HS code and its total price. Also, AnyLogic, a comprehensive simulation modeling tool, the simulation will be conducted to identify the paths for illegal transfer and calculate the time required. The information on North Korea’s trading partners and items is used for establishing export scenarios in which strategic items are transferred to other countries through North Korea’s ports, airports, railroads, and roads. To be specific, China, Russia, and South Korea, countries that share a border with North Korea, export items transported only by land; the items will arrive first in the referred three countries. Since the types of items, North Korea transacts with each country are different, the total amount and frequency of transactions are different; the probability of strategic items being included in general export items and transferred during customs clearance also varies. Even if it does not border North Korea, North Korea can export items through ports to countries adjacent to the coastline, and North Korea can even export items to any country by airspace even if it is not adjacent to the coastline. So, all publicly open ports, airports, railways, and roads are surveyed. Their geographic information, such as EPSG 4326 and EPSG 3857 coordinate system, are applied to confirm and visualize valid export paths starting from North Korea. In conclusion, effective export paths in North Korea are identified based on North Korea’s each major transportation hub by using AnyLogic simulation. It is possible to predict the paths through which North Korea’s strategic items will be transferred by combining information on major export items and countries that North Korea mainly transacts with.

KINAC is trying to build a comprehensive aerial view of the nuclear material balance to predict North Korea’s weapons-grade nuclear material production capacity. We are creating a visualization model for North Korea’s nuclear facilities as part of these efforts. However, information on North Korea’s nuclear facilities is scarce, and it is not easy to consider additional facilities other than those already known. In addition, in the case of a model that targets only exceptional situations, it is not easy to secure objectivity for model validation, so it is necessary to upgrade to a general-purpose analysis tool that can be applied more generally. The following two examples are proposed as an analysis tool that can be a high degree of analysis. The first case is an Acquisition Path Analysis (APA) utilized to introduce IAEA’s State-Level Approach (SLA). The acquisition path analysis aims to find and evaluate the technically possible pathways to obtain nuclear materials for nuclear weapons or other nuclear explosive development. It can be an acquisition route if it is possible to produce at least 1 Significant Quantity (SQ) of weapongrade nuclear material within five years. The assessment of technologically feasible pathways is based on available information about the country’s past and present nuclear cycle capabilities. The second is the IAEA Physical Model. The IAEA Physical Model was carried out to introduce a comprehensive approach to all information on a country’s nuclear activities. It describes and characterizes the technologies and processes expressed at all levels of the acquisition path, depending on the development objectives. The IAEA Physical Model attempts a multi-tiered acquisition path analysis to identify all known technologies and processes in the nuclear fuel cycle, from raw material production to weapon usable material acquisition. Based on this analysis, the IAEA evaluates the signs of nuclear proliferation in a specific country. Based on the two cases discussed above, we intend to derive the following implications and priorities for extending the existing nuclear cycle model to a more general-purpose for a specific country. First of all, the requirements necessary to evaluate nuclear non-proliferation or verification of denuclearization must be at a level that the international community can recognize. In the stage of actual denuclearization verification, since verification will be conducted through the IAEA, a corresponding level of tools and technology will be required. From this point of view, the following is presented as a prerequisite for adding versatility to the existing physical model: It is necessary to derive all processes related to the nuclear cycle and standardize relevant indicators and data. In order to determine the signs of nuclear activity, detailed information on technologies, materials, by-products, and wastes, which are essential for each process, is required. For denuclearization verification, cumulative information from the past to the time point is required, and a comparative analysis of the operation history information of all facilities and the amount of nuclear material is required. To this end, it is necessary to make it possible to trace the history at every point where it can be determined that nuclear material has been diverted so that missing nuclear material can be found. Based on this, it is expected that it can be possible to evaluate a hypothetical threat state, but it is also expected that it will be easy to verify the model through the evaluation of easily accessible domestic facilities.

With the rapid improvement of hardware and software-related IT technology, applying A.I. to the private and public sectors, such as the Food Poisoning Prevention Program in Nevada and Smart City based on big data in Boston, is steadily increasing. However, the cases of application to the regulation sector of government are still insufficient. The Korea Institute of Nonproliferation and Control (KINAC) is studying to apply A.I. technology to the regulation to improve the objectivity, consistency, and efficiency of classification and export licensing review. The KINAC developed the Nation Nuclear Technology Information Collection and Analysis System using A.I. techniques such as machine learning and deep learning techniques. KINAC and FNC Technology are developing the Export Risk Assessment System using A.I. modules and Bayesian Networks. The KINAC and Korea Atomic Energy Research Institute (KAERI) are developing an inventory history management system subject to the Nuclear Cooperation Agreements. The Nuclear Safety and Security Commission (NSSC) and KINAC operate the Nuclear Import and Export Control System (NEPS) for application and export license review according to relevant laws such as the Foreign Trade Act. Therefore, preparing an integration plan for the existing NEPS and the new systems is necessary. Since the NEPS has to be operated and accessible at all times, so the stability of the NEPS is the most important when integration and linking. So, it is suggested that the Collection and Analysis System and the Risk Assessment System, which require a lot of data traffic, are configured in a server separate from the NEPS, and the new DB and the NEPS DB are only linked. An inventory history management system is also suggested to be integrated and configured into the NEPS. Third, it is recommended that each system lists the information provided to or received from the NEPS in advance, and one-way communication should be performed basically. Two-way communication should be performed when necessary. Finally, against various cyber accidents and information leakage, it is proposed to review security vulnerabilities and apply essential security measures and guidelines. Through the integration and linkage of these systems, it is expected that the objectivity, consistency, and efficiency of classification and export licensing review of the KINAC are strengthened, and national transparency of development, production, and use of nuclear material is enhanced. It can be satisfied with the increasingly strengthened demands of the international community on duty for strategic item management.

In accordance with the Enforcement Decree of the Act on Physical Protection and Radiological Emergency, operators of Nuclear Power Plants (NPP)s must conduct full cyber security exercise once a year and partial exercise at least once every half year. Nuclear operators need to conduct exercise on systems with high attack attractiveness in order to respond to the unauthorized removal of nuclear or other radioactive material and sabotage of nuclear facilities. Nuclear facilities identify digital assets that perform SSEP (Safety, Security, and Emergency Preparedness) functions as CDA (Critical Digital Assets), and nuclear operators select exercise target systems from the CDA list and perform the exercise. However, digital assets that have an indirect impact (providing access, support, and protection) from cyber attacks are also identified as CDAs, and these CDAs are relatively less attractive to attack. Therefore, guidelines are needed to select the exercise target system in the case of unauthorized removal of nuclear or other radioactive material and sabotage response exercise. In the case of unauthorized removal of nuclear or other radioactive material, these situations cannot occur with cyber attacks and external factors such as terrorists must be taken into consideration. Therefore, it is necessary to identify the list of CDAs that terrorists can use for cyber attacks among CDAs located in the path of stealing and transporting nuclear material and conduct intensive exercise on these CDAs. A typical example is a security system that can delay detection when terrorists attack facilities. In the case of sabotage exercise, a safety-related system that causes an initiating event by a cyber attack or failure to mitigate an accident in a DBA (Design Basis Accident) situation should be selected as an exercise target. It is difficult for sabotage to occur through a single cyber attack because a nuclear facility has several safety concepts such as redundancy, diversity. Therefore, it can be considered to select an exercise target system under the premise of not only a cyber attack but also a physical attack. In the case of NPPs, it is assumed that LOOP (Loss of Offsite Power) has occurred, and CDA relationships to accident mitigation can be selected as an exercise target. Through exercise on the CDA, which is more associated with unauthorized removal of nuclear or other radioactive material and sabotage of nuclear facilities, it is expected to review the continuity plan and check systematic response capabilities in emergencies caused by cyber attacks.

KINAC (Korea Institute of Nuclear Non-proliferation and Control) is entrusted with the NSSC (Nuclear Safety And Security Commission) to conduct threat assessments for nuclear facilities. As part of the threat assessment, DBT (Design Basis Threat) must be established every three years, and a threat assessment report must be developed for DBT establishment. This paper suggests a method for collecting and analyzing cyber threat information for the development of a cyber security threat assessment report. Recently, cyber threats not only in the IT (Information Technology) field but also in the ICS (Industrial Control System) field are rapidly increasing. As cyber threats increase, threat information including related attack techniques is also increasing. Although KINAC is conducting a threat assessment on cyber security at nuclear facilities, it cannot collect and analyze all cyber threat information. Therefore, it is necessary to determine a reliable source of threat information for threat assessment, and establish a strategy for collecting and analyzing threat information for DBT establishment. The first method for collecting and analyzing threat information is to first collect threat information on industrial fields with high similarity to nuclear facilities. Most of the disclosed cyber threat information is in the IT field, and most of this information is not suitable for closed-network nuclear facilities. Therefore, it is necessary to first collect and analyze threat information on facilities that use networks similar to nuclear facilities such as energy and financial sector. The second method is to analyze the attack technique for the collected threat information. The biggest factor in DBT reset is whether there is a new threat and how much it has increased compared to the existing threat. Therefore, it is necessary to analyze which attack technique was used in the collected threat information, and as part of the analysis, a cyber attack analysis model such as a kill chain can be used. The last method is to collect and manage the disclosed vulnerability information. In order to manage vulnerabilities, it is necessary to analyze what assets are in the nuclear facility first. By matching the reported vulnerability with the CDA (Critical Digital Asset) in the facility, it is possible to analyze whether the CDA can be affected by a cyber attack.As cyber threats continue to increase, it is necessary to analyze threat cases of similar facilities, attack techniques using attack models, and vulnerability analysis through asset identification in order to develop a threat assessments report.

Nuclear operators must sort out their digital assets as Critical Digital Asset (CDA) and manage their vulnerabilities. Since vulnerabilities are continually found and can be abused anytime, and the number of digital assets in nuclear facilities is increasing, it is important to collect publically-known vulnerabilities in automated mechanism to reevaluate their risks. KINAC is now in progress of establishing an automated mechanism of collecting publically-known vulnerabilities for nuclear facilities. This paper will discuss about criteria of selecting database when establishing an automated mechanism of collecting publically-known vulnerabilities for nuclear facilities. When selecting sets of vulnerability database, the characteristic of sets of digital assets need to be managed, importance of each digital asset, and where and who will use the set of digital assets should be mainly considered. Most of safety-related CDAs are made and used in the United States, and safety-related CDAs are similar to Information and Communication Technology (ICT) facilities. Therefore, the main vulnerability database used in the United States should be included when collecting the database of vulnerabilities. Especially, US government actively provides vulnerabilities of digital assets, enacting vulnerability disclosure policy to make each organization report their own potential vulnerabilities. The main vulnerability database of the US is National Vulnerability Database (NVD) of NIST. It contains over 150,000 vulnerabilities on ICT and Industrial Control System (ICS). Nuclear Energy Institute (NEI) published “Cyber Security Vulnerability and Risk Management”, Addendum 5 to NEI 08-09, and informed that US-CERT, ICS-CERT, and NVD can be used as publically-known vulnerability database, and US National Regulatory Commission (NRC) endorsed the publication. In South Korea, KrCERT and National Cyber Threat Intelligence (NCTI) share publically-known vulnerabilities, however, the number of vulnerabilities are less than those of NVD, and most of the data are duplication of those of NVD. Moreover, certain portion of information are only opened to authorized organizations, so it is unable to access those databases. Therefore, considering the fact that most information of vulnerabilities of CDAs are included in NVD and ICS-CERT, vulnerability database should also contain information from NVD and ICS-CERT. Otherwise, the database must contain equivalent information compared to NVD and ICS-CERT. Furthermore, the methodology for collecting vulnerabilities of digital assets from other countries is also required to be studied in the future research.

With the enhancement of the spatial resolution of satellite imagery (1 m or less), the satellite image analysis has been considered as the indispensable means for remote sensing of nuclear proliferation activities in the restricted access areas such as North Korea. Notably, in the case of an open-pit uranium mine, e.g. the Pyongsan uranium mine, the mining activity can be presumed if detecting the location and extent uranium tailing piles near shafts within temporal images. Several studies have researched on the target detection for minerals of interest such as limestone and coal to evaluate the economic activities by utilizing similarity measures, e.g., a spectral angle mapper and a spectral information divergence (SID). Thus, this paper presented a systematic change detection methodology for monitoring the uranium mining activity in the Pyongsan uranium mine with a similarity measure of SID. The proposed methodology using the target detection results consists of the following five steps. The first step is to acquire stereo images of areas of interest for change detection. The second step is to preprocess the stereo images as following measures: (i) the QUick Atmospheric Correction and the image-to-image registration with ENVI and (ii) the Gram-Schmidt pansharpening. The third step is to extract spectral information for minerals of interest, i.e., uranium tailing piles, by sampling pixels within the reference image. It is based on the satellite analysis report for the Pyongsan uranium mine by CSIS, which specified the location of the uranium tailing piles. As the fourth step, the target detection for uranium tailing piles was performed through the similarity measure of SID between the extracted spectral information and the spectral reflectance of the image. In the fifth step, the change detection was processed using the multivariate alteration detection algorithm, which compares the target detection results by canonical correlation analysis. Furthermore, this paper evaluated the performance of the proposed methodology with the change detection accuracy assessment index, i.e., the area under a receiver operating characteristic curve. In conclusion, this paper suggests the systematic change detection methodology utilizing time series analysis of target detection for uranium tailing piles, which can save time and cost for humans to interpret large amounts of satellite information at the restricted access areas. As future works, the feasibility of the proposed methodology would be investigated by analyzing distribution of minerals of interest regarding nuclear proliferation at Yongbyon, which has the historical events of suspicious nuclear activities.

Dry storage cask facilities are considered for temporary storage of spent nuclear fuels before their final disposal. According to relevant domestic laws and regulations, the integrity and gross defects of the PWR spent fuel must be inspected before they are transferred to the dry cask from a wet storage pool of a nuclear power plant. To meet nuclear safeguards requirements for a spent fuel transportation, the KINAC has been working to develop a simple and convenient Non-destructive Testing (NDT) equipment to verify the integrity and gross defects of the spent fuel assembly. This study was conducted in two processes. The first stage is to review the current NDT techniques conducted in the nuclear fuel manufacturing process. During the manufacturing process, the Ultrasonic testing (UT) and Eddy Current Testing (ECT) technique are used for detecting the cracks or foreign materials in a cladding of a fresh fuel. During an over-haul period after an end of one fuel cycle, the sipping test of the spent fuel is performed for detecting the failed fuel assemblies. If it is determined through the sipping test whether any fuel assembly contains a failed fuel rod, the failed fuel rod of lots of fuel rods in the assembly is found out using the UT instrument. The ECT is used for detecting the internal defects and oxide layer thickness of a fuel cladding. Because the UT and ECT are the wellknown technique and has already been employing for the spent fuel inspection, we adopted the UT and ECT technique for development of a new instrument for nuclear safeguards verification. The second stage is to design the UT and ECT equipment in consideration of nuclear safeguards activities in the spent fuel pool. For nuclear safeguards inspection, irradiated fuel or non-fuel items are distinguished. Thus, verification equipment newly designed using the UT and ECT should detect not only a failed rod, but also a false tube, or a false rod, or a different material from a cladding. New probe and signal processing methods are developed to achieve these goals. The design of UT and ECT probes are preferentially carried out according to technical requirements – the probe thickness including a damper material should be less than 1.0 mm - and the study on analyzing signal distortion caused from material difference will be conducted for development of the safeguards inspection equipment. Detailed results of our study will be discussed in this conference.

Since 2017, the Korea Institute of Nuclear Nonproliferation and Control (KINAC) has been implementing State System of Accounting for and Control of Nuclear Materials (SSAC) training courses for the nuclear Newcomer States. This IAEA SSAC course for Newcomer States aims to provide overall concepts and techniques, particularly on nuclear material accountancy and control systems, and address future challenges with regard to developing new nuclear power plants. Due to the restricted travels and limited in-person access to training and facilities from the COVID-19 pandemic, however, a new software was developed to substitute a technical tour on bulk handling facility (BHF) of the training course, and the course was favorably shifted to online in 2021. This newly built training software allows participants to follow each step of the technical process at a virtual bulk handing facility, and provides a video tour for such conditions where the software is found difficult to operate. Another feature of the development is a security function that prevents access of unauthorized users to the software. The achievement is expected to strengthen the SSAC of Newcomer States and ensure the practical implementation of safeguards from the initial stage of their novel nuclear power program through cooperation with IAEA. This contribution of the Republic of Korea (ROK) as one of the leading countries in the field of nuclear nonproliferation will further extend the partnership between IAEA and ROK and promote cooperation with the Newcomer States.

Bayesian statistics, which is an approach to analyzing data based on Bayes’ theorem, is currently widely used in all fields. However, it has been applied very limitedly to studies related to nuclear nonproliferation. Therefore, this paper provides a knowledge base and directions for using various Bayesian techniques in nuclear non-proliferation. First, the concepts and advantages of the Bayesian approach are summarized and the basic solving methods of Bayesian inference are explained. The Bayesian approach enables more precise posterior estimation using the prior probability and the likelihood functions. To solve Bayes’ theorem, it is necessary to use the conjugate prior distribution, which is analytically solvable, or to use a numerical approach with computing power. Next, for several Bayesian statistics methods, the purpose of use and the mathematical derivation process are described. Bayesian linear regression analysis aims for obtaining a function that outputs the closest value to data of variables and results. Factor analysis is mainly used to derive a smaller number of unobserved latent variables that can represent observed variables. The logit and probit model are nonlinear regression models for when the outcome is binary. The hierarchical model is to analyze by introducing hyper-parameters in an integrated manner when there are several groups of similar data. The Bayesian approach of these methods is generally based on the numerical solution of the Bayesian inference of the multivariate normal distribution. Finally, the previous researches that each introduced method have been applied to nuclear non-proliferation are investigated, and research topics that can be applied in the future are suggested. Bayesian statistics have been mainly used for precise estimation of the amount, location, and radioactivity spectrum of nuclear materials using detectors. Using Bayesian approach, it will be possible to perform various analyzes. For example, the change of activeness of nuclear program can be estimated by Bayesian inferences on the frequency and scale of nuclear tests. And it can be tried predicting the production of plutonium according to the core configuration and burnup using the Bayesian linear regression. Also, by introducing the Bayesian approach to factor analysis or logit analysis of nuclear development motives or nuclear proliferation probability, it can be expected to improve precision. With the development of computer technology, the use of Bayesian statistics increases rapidly. Based on the theory and applied topics summarized in this paper, it is expected that Bayesian statistics will be more actively used for nuclear non-proliferation in the future.

Korea Institute of Nuclear Nonproliferation and Control (KINAC) remains dedicated to providing national and international training to train the workforce in the area of nuclear nonproliferation and security. INSA has also provided a number of nuclear nonproliferation courses for the public such as middle or high school students and teachers, senior government officials, NGOs in the field of nuclear energy, and so on. The recent trend calls for education with high field applicability. Additionally, as interest in nuclear nonproliferation has recently increased, the demand of the public for education is expected to be increased. However, since it is difficult for the public to access nuclear facilities, it is not easy to understand regulatory activities at nuclear facilities. Therefore, KINAC has developed Virtual Reality (VR) content to enhance the public’s understanding of nuclear facilities and on-site inspection activities of KINAC. VR technology is expected to be a new means that can enable the public to access nuclear facilities in spite of some “VR dizziness” usually called “Human Factor”. This paper introduces the composition and function of KINAC’s nuclear nonproliferation VR content for Hanaro Rx in nuclear nonproliferation courses for the public and seeks ways to optimize it based on a one-year operation experience.

Sandia National Laboratories is the lead laboratory for the United States Department of Energy for the research and development (R&D) efforts to support the technical basis for the long-term storage, subsequent transportation, and permanent disposal of commercial spent nuclear fuel and high-level waste. Sandia does not design nuclear facilities; Sandia performs R&D to help ensure facilities and the fuel cycle are safe, sustainable, and secure. This talk will focus on the spent fuel storage and transportation programs that contribute to this work. The goal in spent fuel storage and transportation R&D is to understand the mechanical integrity of the fuel, cladding, and storage system beyond interim storage and into disposal time frames. Our research is focused on understanding the high burn-up cladding integrity over time, understanding the thermal behavior during drying and storage, understanding potential cladding oxidation pathways, and quantifying in the external loads experienced during transportation, handling, and seismic events. Additionally, this work includes extensive work to understand the basic science of canister stress corrosion cracking and the potential consequences of a through wall canister crack.

The purpose of this study is to develop the analysis procedures for the evaluation of the structural integrity of the spent fuel in normal condition of transport at sea. Spent nuclear fuel must be transported from the wet storage facility in the nuclear power plant to the intermediate storage facility, and the structural integrity must be maintained in vibration and shock loads during the transportation. In general, the transport of spent nuclear fuel is performed in three kinds of modes: road, rail, and sea. During transport, the spent nuclear fuel is subjected to repeated vibration and shock loads by road surfaces, railroad tracks, and waves of the sea. It should be evaluated whether the structural integrity of the spent fuel is maintained under these load conditions. All nuclear power plants in Korea are located in coastal sites, and the interim storage facility for spent nuclear fuel is highly likely to be decided as a coastal site as well. Therefore, the main mode of the spent nuclear fuel transport is expected to be maritime transport by ships. In this study, the analysis procedure was developed to evaluate the safety of spent fuel at maritime transport by ships, and the procedure for evaluating the integrity of spent fuel under normal conditions of maritime transport were proposed. CFD analysis using SeaFEM was performed for the vibration analysis of the ship by waves, and the structural vibration analysis of the transport system was simulated using the developed in-house codes. The fatigue durability of the cladding was also evaluated using the developed fatigue analysis program and the fatigue analysis used the strain data obtained from the structural analysis. It was concluded that the value of the fatigue damage on the spent fuel cladding during normal conditions of maritime transportation is close to “0” and the structural integrity of the spent fuel is maintained in the same condition.

The temperature of the spent fuel cladding is the basis for the evaluation of integrity. It is almost impossible to directly measure the temperature of spent nuclear fuel. Because spent nuclear fuel is dangerous. We are preparing a test to measure the cladding temperature with an equivalent fuel assembly by simulating the characteristics of spent nuclear fuel. PLUS7 was selected as the test target in consideration of the amount of generation, thermal water retention, residual moisture content, and manufacturability of domestic spent nuclear fuel. The nuclear fuel assembly is planned to be manufactured in two main ways. Except for the cladding tube that simulates decay heat, the structure will be manufactured by KEPCO Nuclear Fuel, and fuel rods and canisters will be manufactured by SUKEGAWA Electric in Japan. The same nuclear fuel assemblies as commercial skeleton will be applied. The temperature of the fuel cladding will be measured by attaching a thermocouple directly to the surface of the cladding tube. The canister is composed of a basket, a basket supporter, a heater and drain tube, a lead, and an observation window. The working fluid is water and helium, and the maximum pressure inside the canister is 1.1 MPa and the minimum pressure is 0.05 kPa. The maximum temperature of the surface of the cladding was designed to be 500°C, and the maximum temperature of the sealing to keep airtightness was designed to be 250°C. To satisfy this condition, we plan to evaluate the leak rate below 10−5 std.cm3·s−1, which is equivalent to helium tightness. The maximum heat of decay per fuel rod is 13 W, and one assembly is up to 3 kW. Production of the test equipment is expected to be completed in the first half of next year, and testing is scheduled to begin in the second half of next year. The test will evaluate all environments that the spent nuclear fuel may experience, such as dry normal conditions, abnormal conditions, wet conditions, and dry conditions. All data will be used for interpretation verification purposes.

Molten Salt Reactor (MSR) is one of the generation-IV advanced nuclear reactors in which hightemperature molten salt mixture is used as the primary coolant, or even the fuel itself unlike most nuclear reactors that adopt solid fuels. The MSR has received a great attention because of its excellent thermal efficiency, high power density, and structural simplicity. In particular, since the MSR uses molten salts with boiling points higher than the exit temperature of the reactor core, there is no severe accident such as a core melt-down which leads to a hydrogen explosion. In addition, it is possible to remove the residual heat through a completely passive way and when the fuel salt leaks to the outside, it solidifies at room-temperature without releasing radioactive fission products such as cesium, which make the MSR inherently safe. Both fluoride and chloride mixtures can be used as liquid fuel salts by adding actinide halides for MSRs. However, the MSRs using chloride-based salt fuels can be operated for a long time without adding nuclear fuel or online reprocessing because the actinide solubility in chloride salts is about six times higher than that in fluoride salts. Therefore, the chloride-based MSRs are more effective for the transmutation of long-lived radionuclides such as transuranic elements than the fluoride-based MSRs, which is beneficial to resolve the high radioactive spent nuclear fuel generated from light water reactors (LWRs). This paper examines liquid fuel fabrication using an improved U chlorination process for the chloride-based MSRs and presents the strategy for the management of gaseous fission products generated during the operation of MSR.

This presentation summarizes recent research on estimating the mechanical loading environment of spent nuclear fuel (SNF) during normal storage and transportation scenarios sponsored by the US Department of Energy Spent Fuel and Waste Science and Technology (SFWST) program. Normal conditions of truck, ship, and railroad transportation of SNF were studied with testing and numerical modeling to determine that the shock and vibration loads applied to SNF during transportation are not expected to challenge SNF cladding integrity or the fatigue life of cladding. The 30 cm package drop scenario was studied with experiments and modeling to determine that mechanical loads during a 30 cm SNF package drop scenario are only expected to challenge SNF cladding integrity under worstcase conditions at elevated temperatures. The SFWST program is currently preparing seismic shake table testing to record SNF mechanical loads in a dry storage earthquake scenario. This presentation summarizes the findings of the transportation and package drop research and details the progress made on the current seismic test.

In South Korea, the master plan for high-level radioactive waste management, announced in 2016, suggested the construction and operation of intermediate storage facilities on a permanent disposal site and specified the adoption of dry storage in consideration of the ease of operation and expansion. As of 2021, the government is again reviewing its overarching policy on the back-end fuel cycles, including intermediate storage and permanent disposal. In the case of dry storage facilities, safety evaluation is being conducted using a combination of deterministic and probabilistic approaches, similar to that of nuclear power plants. The two methods are complementary, of which Probabilistic Safety Assessment (PSA) has the advantage of being able to identify key scenarios affecting safety, but its use in storage facilities has not been highlighted so far. However, depending on the spent fuel management phases such as loading, transportation, and storage, it may be not enough to capture effective and efficient safety evaluation only deterministically, and probabilistic methods may contribute to the evaluation of long-term operation or external events such as an earthquake. There have already been cases where PSA has been performed on a part of the nuclear fuel cycle through previous studies. This paper created the safety assessment model based on open sources such as the released EPRI reports, by targeting arbitrary intermediate storage facilities. The model considered the scenarios for loading, transportation, and storage, with human error respectively. It will be able to be modified and improved to fit domestic and specific intermediate storage facilities in the future.