Sungyeol Choi

Dynamic assessments on high-level waste and low- and intermediate-level waste generation from open and closed nuclear fuel cycles in Republic of Korea

We estimated the generation of low- and intermediate-level waste (LILW) and high-level waste (HLW) from open and closed nuclear fuel cycles. The closed fuel cycle reflects the development and deployment of fast reactors and pyroprocessing from 2013 to 2100, while the open fuel cycle only considers pressurized water reactors. The closed fuel cycle hardly affects short-term spent fuel management but can save nearly 60% space of interim storage compared with the open fuel cycle. Compared with the open fuel cycle, the accumulated volume of HLW can be significantly reduced in the closed fuel cycle up to over 95% in 2100. For this volume reduction, high heat generating fission products should be separated from transuranic waste in pyroprocessing and stored in decay storages for a few hundred years. Mining and milling waste in the closed fuel cycle decreases by about 31%. In contrast, the closed fuel cycle generates 3.0%–4.5% more LILW than the open fuel cycle because fast reactors and pyroprocessing produce more LILW and conversion, enrichment, and fabrication produce less LILW. In the closed fuel cycle, operation and decommissioning wastes from reactor and pyroprocessing, respectively, contribute to 74% and 8% of LILW excluding mining and milling waste.

URANUS: Korean Lead-Bismuth Cooled Small Modular Fast Reactor Activities

Since 1994, Seoul National University (SNU) has developed an innovative future nuclear power based on LBE cooling advanced Partitioning and Transmutation (P&T) approach that leaves no high-level waste (HLW) behind with transmutation reactor named as Proliferation-resistant, Environment-friendly, Accident-tolerant, Continual, and Economical Reactor (PEACER). A small modular lead-bismuth cooled reactor has been designated as Ubiquitous, Robust, Accident-forgiving, Nonproliferating and Ultra-lasting Sustainer (URANUS-40) with a nominal electric power rating of 40 MW (100 MW thermal) that is well suited to be used as a distributed power source in either a single unit or a cluster for electricity, heat supply, and desalination. URANUS-40 is a pool type fast reactor with and an array of heterogeneous hexagonal core, fueled by proven low-enriched uranium dioxide fuels. The primary cooling system is designed to be operated by natural circulation. 3D seismic base isolation system is introduced underneath the entire reactor building allowing an earthquake of 0.5g zero period acceleration (ZPA) for the Safe Shutdown Earthquake (SSE). Also, the proliferation risk can be effectively managed by capsulized core design and a long refueling period (25yr).Copyright

Computational electrochemo-fluid dynamics modeling in a uranium electrowinning cell

A computational electrochemo-fluid dynamics model has been developed to describe the electrowinning behavior in an electrolyte stream through a planar electrode cell system. Electrode reaction of the uranium electrowinning process from a molten-salt electrolyte stream was modeled to illustrate the details of the flow-assisted mass transport of ions to the cathode. This modeling approach makes it possible to represent variations of the convective diffusion limited current density by taking into account the concentration profile at the electrode surface as a function of the flow characteristics and applied current density in a commercially available computational fluid dynamics platform. It was possible to predict the conventional current–voltage relation in addition to details of electrolyte fluid dynamics and electrochemical variables, such as the flow field, species concentrations, potential, and current distributions throughout the galvanostatic electrolysis cell.

Effects of Nuclear Technology Export Competition on Nuclear Nonproliferation

ABSTRACT While nuclear suppliers compete in markets, they simultaneously partner in other fields. This produces a delicate relationship between civilian nuclear programs and nuclear weapon proliferation. This study explores how export competition affects suppliers’ conditions of supply related to nuclear nonproliferation. We investigated three export cases (India, North Korea, and South Korea) and identified four effects that competition has on the conditions of supply related to nonproliferation. First, under highly competitive conditions, suppliers might hesitate to enforce the conditions of supply to avoid negotiation conflicts with recipients. Second, suppliers focus on politically and economically attractive recipients while mostly ignoring unattractive ones, perhaps allowing proliferation problems to fester out of view in marginal states. Third, suppliers can build consensus on the conditions of supply to avoid being the only party experiencing negotiation conflicts. Fourth, suppliers can constrain others from relaxing the conditions of supply to maintain economic benefits and nonproliferation norms. The first two effects accelerate proliferation while the last two promote nonproliferation. Although the extent of these effects can vary with changes in nonproliferation norms, they can contribute to our understanding of the relationship between nonproliferation and civilian nuclear programs.

Multinational planning of nuclear energy systems in Asia

ABSTRACT The rapid growth of nuclear power market in Asian regions will introduce a high demand for fuel cycle services; however, in line with nonproliferation goals, control of sensitive technologies needs to be institutionalized. Multinational approaches to nuclear fuel cycle have been suggested for this purpose, but only limited initiatives are visible in the front-end; there has been a gap relating to the back-end fuel cycle. This paper concludes that a tangible and practical approach should be initiated with focus on the management of spent nuclear fuels (SNFs) in Asia, because it can provide a common goal for cooperation. The most applicable technology to ensure nonproliferation would be partitioning and transmutation (P&T), which can eliminate the accumulation of high-level wastes with adequate proliferation resistance and economic viability via black-box measures. As a long-term project, this requires a stepwise plan for research and eventual industrial development.