Korea Atomic Energy Research Institute (“KAERI”) has been developing pyroprocess technology for the sustainable use of nuclear energy and radioactive waste reduction, and is conducting design studies for a Pyroprocess Commercializing Research Facility (PCRF). High-level radioactive materials such as spent nuclear fuel, which are handled in the hot cell of the PCRF, physically change materials directly or cause chemical changes through ionization or excitation depending on the energy and types of radiation. Therefore, all facilities, including process equipment and remote handling equipment, installed into the hot cell must be evaluated for radiation hardness to be maintained in the radiological environmfent so that processes can proceed throughout the design life of the facility. In addition, as the maintenance paradigm has recently shifted from corrective maintenance to predictive maintenance, it is necessary to know in advance the condition of the equipment or facility in the radiological environment. In this study, an analysis of the radiation environment of the hot cell in the PCRF was conducted through source term, and the radiological dose impact was evaluated through the results of irradiation experiments of major components by reference data. Then, the actual dose contribution was identified through dose assessment using the MCNP code based on the pyroprocess equipment, and the radiation hardness requirements for the facility and equipment in the hot cell were derived by the above results.

This paper describes the development and operation of an autonomous robotic system designed for pyroprocess automation. The unique challenges of pyroprocess automation, such as the need for a highly dry atmosphere to handle materials like chloride, are addressed through this system. For the experiments, a specialized dehumidifier and dry mock-up facility were designed to produce dry air condition. Performances of dry air conditioning for the various simulated situations were evaluated, including assessing worker access within a mock-up to determine the system’s feasibility. To enable automation, containers used for processing materials were modified to fit the gripper system of the gantry robot. The loading and unloading of materials in each equipment were automated to connect them with the robotic system. This gantry robot primarily utilized macro motions to approach waypoints containing process materials, reducing the need for precise approach motions. Its tapered jaw design allowed it to grip target objects even with imperfect positioning. The robot’s motions were programmed initially using a robot simulator for positioning and motion planning, and real-world accuracy was tested in a dry mock-up facility using the OPC platform. Finally, the paper discusses the potential application of XR (eXtended Reality) technology in this context, which could enhance the robot’s operation and provide valuable insights into the automation process. Further analysis of XR technology’s feasibility and benefits for this specific pyroprocess automation system are presented.

As part of strengthening pyro safety measures, the Korea Atomic Energy Research Institute is developing LIBS (Laser-Induced Breakdown Spectroscopy) application technology to analyze molten salt components in electrolytic recovery device in real time. LIBS performs qualitative and quantitative analysis by analyzing the spectrum of energy emitted by atomizing and ionizing elements on the surface of a salt sample with a high-focused laser. Since salt easily corrodes metal, it must be managed in an environment with a dew point of -40°C or lower. In this study, we designed and manufactured a device that places a rod-type sampling stick on a mounting base, automatically moves it to the optimal measurement position for LIBS, and retrieves the sample. Its characteristics are as follows. First, LIBS is stationary and does not move. Second, the sample stick is placed on a mounting base and can rotate 360 degrees. Third, according to the command, the sample stick automatically moves to the optimal measurement position of LIBS with three degrees of freedom (X, Y, Z). Fourth, the salt attached to the sampling stick is recovered for chemical analysis by driving the gripper mounted at the bottom of the Z axis, Z axis, and rotation axis (R). The X, Y, and Z movement distances of this device are each 100 mm, rotation is 360 degrees, grip stroke is 50 mm, and position accuracy is ±20 m. Once the performance test of the automated salt sample analysis device is completed, it will be installed in a dry room with a dew point of - 40°C or lower. Samples will be collected remotely in connection with the electrolytic recovery device and gantry robot built in the dry room. We plan to conduct experiments to seat the sample stick. Ultimately, we plan to conduct comprehensive experiments in conjunction with LIBS.

The process basket assembly is an important module in pyroprocess, because pyroprocess is a batch process, so process materials are contained in a basket assembly and transferred with the basket. The basket assembly is composed of upper and lower assembly. The lower assembly is a basket or crucible which contains process materials, and it can have electrodes. The upper assembly mainly consists of heat shields, a flange, and connectors for supplying currents to electrodes of the lower assembly. During the electrolytic recovery process, the lower part is submerged into molten salt, whose temperature is about 500°C at least and the heat from salt is transferred to the upper assembly. And the heat affects the performance or durability of parts on the top of equipment and can raise cell temperature, which is an undesired situation. In addition, the handling equipment can pick the assembly when it is hottest, and during the transfer, the gripped part is under thermal and mechanical stresses. Because of this, the thermal effects from the heat should be required during equipment design stage. In this study, the thermal analyses of process basket assembly were conducted for 3 cases: the steady state of the basket assembly when it submerged in molten salt, the thermal and mechanical stresses when gripped by remote handling device, and the temperature changes under natural convection. These analyses were performed using Solidworks with flow simulation package, and the results will apply to improve the thermal resistant performance of the basket assembly.

원자력 발전 이후에 누적되는 사용후핵연료를 해소하기 위한 다양한 연구가 시도되고 있으며, 특히 건식으로 사용후핵연료 를 재활용하는 파이로 공정이 주목되고 있다. 파이로 공정의 공학규모 실증을 위하여 대형 공정셀을 구비한 PRIDE 시설이 구축되었다. 파이로 공정에 사용되는 용융염의 화학반응성을 고려하여, 공정셀 내부는 아르곤 분위기를 유지한다. 결과적으 로, 작업자가 공정셀 내부에 진입할 수 없으며, 공정셀 내부에 설치된 모든 공정장치는 원격수단에 의해 공정셀 밖에서 원격 조작을 통해 수행한다. 따라서, 공정셀에 설치되는 공정장치는, 설계단계에서 부터 원격작업을 고려하여 설계되어야 하며, 공정셀에 반입하기 전에 원격으로 작동이 가능한지 철저히 검증하여야 한다. 만약, 공정셀에 반입되어 작동하는 단계에서 문제가 발생하는 경우, 장치를 반출하여 수정한 후 재반입하기까지 많은 비용과 시간을 허비하게 된다. 공정장치의 원격성 검증을 위하여, 물리적인 목업을 사용할 뿐 아니라, 설계단계에서 3D 모델을 활용한 가상 검증이 가능하다. 본 연구는, 가상공간에 PRIDE 공정셀을 구성하고, 설계된 공정장치 3D 모델을 입력하여, 원격조작성을 검증하기 위한 PRIDE 3D 시뮬레이터 개발에 관한 것이다. 실제 PRIDE 공정셀의 형상과 공정셀에 설치되는 원격운전 및 유지보수 장치의 움직임을 가상공간에 구현하고, 공정장치의 3D 모델을 실제 설치할 장소에 위치할 수 있도록 하였다. PRIDE 공정셀에 설치 될 전해공정장치의 전극교체 작업을 시뮬레이션 시나리오로 설정하여, 개발된 PRIDE 3D 시뮬레이터의 사용성을 검증하고 자 하였다. 8단계로 이루어진 원격작업 시나리오를 구성하여, 각 단계의 원격작업을 성공적으로 모사함으로써, PRIDE 공정 셀의 원격성 평가를 성공적으로 수행하였다.