Geun Il Park

Fractional Release Behavior of Volatile and Semivolatile Fission Products During a Voloxidation and OREOX Treatment of Spent PWR Fuel

Abstract Quantitative analysis of the fission gas release characteristics during the voloxidation and oxidation and reduction of oxide fuel (OREOX) processes of spent pressurized water reactor (PWR) fuel was carried out by spent PWR fuel in a hot cell of the DUPIC Fuel Development Facility. The release characteristics of 85Kr and 14C fission gases during voloxidation process at 500°C are closely linked to the degree of conversion efficiency of UO2 to U3O8 powder, and it can be interpreted that the release from grain boundary would be dominated during this step. Volatile fission gases of 14C and 85Kr were released to near completion during the OREOX process. Both the 14C and 85Kr have similar release characteristics under the voloxidation and OREOX process conditions. A higher burnup spent fuel showed a higher release fraction than that of a low burnup fuel during the voloxidation step. It was also observed that the release fraction of semivolatile Cs was ~16% during a reduction at 1000°C of the oxidized powder, but over 90% during the voloxidation at 1250°C.

Remote fabrication of DUPIC fuel pellets in a hot cell under quality assurance program

The Korea Atomic Energy Research Institute (KAERI) has been developing the Direct Use of Spent Pressurized Water Reactor (PWR) Fuel in the CANada Deuterium Uranium (CANDU) Reactors (DUPIC) fuel fabrication technology since 1992, and the basic DUPIC fuel fabrication process was established in 2002. In order to demonstrate the robustness of the DUPIC fuel fabrication process through the irradiation test, it is important that a Quality Assurance (QA) program should be in place before a fabrication of the DUPIC fuel. Therefore, the Quality Assurance Manual (QM) for the DUPIC fuel was developed on the basis of the Canadian standard, CAN3-Z299.2-85. This manual describes the quality management system applicable to the activities performed for the DUPIC fuel fabrication at KAERI. In order to demonstrate the DUPIC fuel fabrication technology and produce qualified DUPIC fuel pellets, the process qualification tests were performed, which include three pre-qualification tests and three qualification tests. The characteristics of the DUPIC fuel pellets such as the sintered density, grain size, and surface roughness were measured and evaluated in accordance with the QA procedures. The optimum fabrication process of the DUPIC fuel pellet was also established based on the qualification results. Finally a production campaign was carried out to fabricate the DUPIC fuel pellets at a batch size of 1 kg following the QA program. As a result of the production campaign, qualified DUPIC fuel pellets were successfully produced and, therefore, the remote fuel fabrication technology of the DUPIC fuel pellet was demonstrated.

Erratum to: Effect of burn-up on the radioactivation behavior of cladding hull materials studied using the ORIGEN-S code

The effect of fuel burn-up on the radioactivation behavior of cladding hull materials was investigated using the ORIGEN-S code for various materials of Zircaloy-4, Zirlo, HANA-4, and HANA-6 and for various fuel burn-ups of 30, 45, 60, and 75 GWD/MTU. The Zircaloy-4 material is the only one that does not contain Nb as an alloy constituent, and it was revealed that 125Sb, 125mTe, and 55Fe are the major sources of radioactivity. On the other hand, 93mNb was identified as the most radioactive nuclide for the other materials although minor radioactive nuclides varied owing to their different initial constituents. The radioactivity of 94Nb was of particular focus owing to its acceptance limit against a Korean intermediate-/low-level waste repository. The radioactivation calculation results revealed that only Zircaloy-4 is acceptable for the Korean repository, while the other materials required at least 4,900 of Nb decontamination factor owing to the high radioactivity of 94Nb regardless of the fuel burn-up. A discussion was also made on the feasibility of Zr recovery methods (chlorination and electrorefining) for selective recovery of Zr so that it can be disposed of in the Korean repository.

Study on an Optimal Condition of Closed Chamber Distillation Equipment for Regeneration of LiCl-KCl Eutectic Salt Containing Rare Earth Phosphates

Abstract In closed chamber distillation equipment, the distillation characteristics of LiCl-KCl eutectic salt containing rare earth phosphates were investigated to establish an operating condition to maximize the operating efficiency of the equipment. To understand the behaviors of LiCl-KCl eutectic salt in the distillation chamber, changes in the pressure in the distillation equipment were observed with a change in the temperature gradients between the vaporization chamber and condensation chamber, and the temperature distributions in the chamber were modeled using computational fluid dynamics software (ANSYS CFX). Based on these results, a model of the salt behavior in the chamber was established, and the most effective operating condition for over 99 wt% of salt recovery was determined. Many distillation experiments of LiCl-KCl eutectic salt containing rare earth phosphates were performed at the condition, and it was confirmed that the salt recovery efficiency (>99 wt%) could be consistently achieved at the condition.

Quaternary Pt2Ru1Fe1M1/C (M=Ni, Mo, or W) catalysts for methanol electro-oxidation reaction

Quaternary Pt2Ru1Fe1Ni1/C (M=Ni, Mo, or W) catalysts were investigated for the methanol electro-oxidation reaction (MOR). Electrocatalytic activities of the quaternary catalysts for CO electro-oxidation were studied via CO stripping experiments, and the Pt2Ru1Fe1Ni1/C and Pt2Ru1Fe1W1/C catalysts exhibited lowered on-set potential compared to that of a commercial PtRu/C catalyst. MOR activities of the quaternary catalysts were determined by linear sweep voltammetry (LSV) experiments, and the Pt2Ru1Fe1Ni1/C catalyst outperformed the commercial PtRu/C catalyst by 170 and 150% for the mass and specific activities, respectively. X-ray photoelectron spectroscopy (XPS) was employed to analyze surface oxidation states of constituent atoms, and it was identified that the structure of the synthesized catalysts are close to a nano-composite of Pt and constituent metal hydroxides and oxides. In addition, the XPS results suggested that the bi-functional mechanism accounts for the improved performance of the Pt2Ru1Fe1Ni1/C and Pt2Ru1 Fe1W1/C catalysts.

DEVELOPMENT OF HIGH- TEMPERATURE TRANSPORT SYSTEM FOR LiCl-KCl MOLTEN SALT IN PYROPROCESSING

Abstract Pyroprocessing technology is one of the most promising technologies for many advanced fuel cycle scenarios with favorable economic potential and intrinsic proliferation resistance. In pyroprocessing technology, the development of high-temperature transport technologies for molten salt is a crucial prerequisite and a key issue in the industrialization of pyroreprocessing. However, there have been a few transport studies on high-temperature molten salt. Three different salt transport technologies (gravity, suction pump, and centrifugal pump) were investigated to select the most suitable method for LiCl-KCl molten salt transport. The suction pump transport method was selected for molten salt transport owing to its flexibility. An apparatus for suction transport experiments was designed and installed for the development of high-temperature molten salt transport technology. Several preliminary suction transport experiments were carried out using the prepared LiCl-KCl eutectic salt at 773 K to observe the transport behavior of LiCl-KCl molten salt. For the experiments, ~2kg of LiCl-KCl eutectic salt was prepared by mixing 99.0% purity LiCl and KCl and drying in a convection dry oven at 473K for 1h. The experimental results of a laboratory-scale molten salt transport using a suction method showed a 99.5% transport rate (ratio of transported salt to total salt) under a vacuum range of 0.0133 to 1.33kPa at 773K. From experimental results on the mass flow rate according to suction transport time, the mass flow rate according to suction time is 1.54kg/min. In addition, to establish engineering-scale salt transport technology, the PRIDE salt transport system was designed and installed in an Ar cell, on the second floor of the PRIDE facility, for engineering-scale salt transport demonstration, and its performance was confirmed.

Modeling and simulation of pyroprocessing oxide reduction

Pyroprocessing operation modeling features complicated batch type operation, tangled material flow logic, handling many numbers of unit processes. Discrete event system (DES) modeling was applied to build an integrated operation model of which simulation showed that dynamic material flow was accomplished. In the model simulation, the amount of material transported through upstream and downstream in a process satisfied the mass balance equation for every batch operation. This study also analysed in detail an oxide reduction process and showed that every streams material flow could be exactly tracked under DES modeling environment.

Discrete event system based pyroprocessing modeling and simulation

The pyroprocessing operation-modelling is characterized as complicated batch type operation and tangled material flow logic, and handling many numbers of chemical elements. Discrete event system modeling was performed to build an integrated operation model, a simulation of which showed that a dynamic material flow was implemented. All data related to a dynamic material flow were recorded in database tables, and used for verification and validation in terms of material balance. Compared to equilibrium material balance, dynamic mass balance showed that the amount of material transported upstream and downstream in the unit process satisfied the mass balance equation at every batch operation. This study also showed that a dynamic material flow, which is a basic framework for an integrated pyroprocessing simulator, was well working. The integrated model built thus far will be improved in a few years toward an integrated simulator with safeguards assessment, technical feasibility, and economic feasibility modules.