Jang-Jin Park

Robotic contamination cleaning system

This paper describes the development of a Robotic Contamination Cleaning System (RCCS) for use in the radioactive zone of the isolation room of the Irradiated Material Examination Facility (IMEF) at the Korea Atomic Energy Research Institute (KAERI). RCCS was designed to completely eliminate human interaction with the hazardous radioactive contaminants. RCCS is capable of cleaning the contaminated floor of the isolation room and collecting loose dry spent nuclear fuel debris and other radioactive waste fixed or scattered on the floor surface. RCCS is operated either by manual control or by autonomous control in conjunction with a graphical simulator, by which the human operator can monitor and intervene RCCS performing cleanup tasks in the isolation room. The mechanical design considerations, control system, and capabilities of RCCS in terms of remote cleanup operation and remote maintenance in the radioactive environment are presented.

Investigation of PWR Hull with a View to Downgrade

Abstract The cladding materials remaining after the reprocessing of nuclear fuel, generally called hulls, are classified as high‐level radioactive waste. They are usually packaged in a container for disposal after being compacted, melted, or solidified into a heterogeneous matrix. Efforts to fabricate a better waste form from an environmental perspective have failed due to the technical difficulties encountered in the chemical decontamination of cladding hulls. In the early 1990s, the accumulation of radiochemical data on hulls and the advent of new technology such as laser or plasma have made the decontamination of hulls a viable option. This paper summarizes information regarding the radiochemical analysis of spent nuclear fuel hulls through a literature survey, including the characteristics of the hulls of 32,000 MWd/tU burn‐up and 15 years cooling of Korean pressurized water reactor. The reduction of the radioactivity by peeling off the inner surface of the hulls via laser technology was evaluated.

A bilateral force reflecting teleoperation system for wiping operation

This paper describes a bilateral force reflecting teleoperation system to wipe a floor surface in a remote manner. This teleoperation system consists of three subsystems - a two degree-of-freedom(dof) master manipulator, a two dof slave manipulator, and a real-time control system. The human operator performs a series of floor wiping tasks controlling the slave manipulator through the master manipulator. A position-force control algorithm is proposed to control the slave manipulators movement, and the contact force occurring between the end-effector of the slave manipulator and the floor surface during wiping. Experiments are performed for evaluating the performance of the developed teleoperation system.

Equipment Arrangements for DUPIC Nuclear Fuel Fabrication and Their Remote Operation and Maintenance in Hot-Cell

DUPIC (Direct Use of spent PWR fuel In CANDU reactors) nuclear fuel that reuses spent PWR (Pressurized Water Reactor) fuel as raw material is being developed at KAERI (Korea Atomic Energy Research Institute). All DUPIC nuclear fuel fabrication processes that mainly consist of powder preparation, pelletization and rod fabrication are conducted in the completely shielded M6 hot-cell of the IMEF (Irradiated Material Examination Facility) at KAERI because of the nature of the high radioactivity of spent PWR fuel. Various types of equipment specially designed for DUPIC fuel fabrication are operated and maintained in a remote manner. This paper presents the in-cell arrangements of all the equipment used for DUPIC nuclear fuel fabrication in the confined hot-cell facility and their remote operation and maintenance in situ.

Mitigation of Radiation Load by Trapping of Tritium in Off-gas during Dry-processes

Although tritium gas is produced a small amount comparing to the other fission products, it should be controlled for long half-life, high residence time, high isotopic exchange rate and ease of assimilation into living matter. A demand for lengthening the life time of disposal site needs treatment of spent nuclear fuel to reduce the volume of high level radwaste. This study is for trapping the tritium gas during dry processes carried out in oxygen condition, having a potential of exposure into operators and environment. The experiments were performed into two different hydrogen concentration ranges, i.e. 1000 ~ 9000 ppm of high range of hydrogen concentration and 25 ~ 100 ppm of low range of hydrogen concentration. At high range of hydrogen concentration, H2O conversion ratio at 400°C indicated above 98 % up to 7000 ppm, and 100% at 450°C. All the results of H2O conversion ratio at the low range of hydrogen concentration are represented close to 99%. Converted H2O vapor was adsorbed at the Molecular sieve close to 100%. More than 98% of H2O conversion ratio was attained up to 4 cm/s of linear gas velocity, whereas over 99% for the low range of hydrogen concentration. Some catalytic effect of ability of conversion hydrogen into H2O on stainless steel was studied.

Hot-Cell Shielding System for High Power Transmission in DUPIC Fuel Fabrication

This paper presents a newly designed hot-cell shielding system for use in the development of DUPIC (Direct Use of spent PWR fuel In CANDU reactors) fuel at KAERI (Korea Atomic Energy Research Institute). This hot-cell shielding system that was designed to transmit high power to sintering furnace in-cell from the out-of-cell through a thick cell wall has three subsystems - a steel shield plug with embedded spiral cooling line, stepped copper bus bars, and a shielding lead block. The dose-equivalent rates of the hot-cell shielding system and of the apertures between this system and the hot-cell wall were calculated. Calculated results were compared with the allowable dose limit of the existing hot-cell. Experiments for examining the temperature changes of the shielding system developed during normal furnace operation were also carried out. Finally, gamma-ray radiation survey experiments were conducted by Co-60 source. It is demonstrated that, from both calculated and experimental results, the newly designed hot-cell shielding system meets all the shielding requirements of the existing hot-cell facility, enabling high power transmission to the in-cell sintering furnace.