A procedure for minimizing the environmental burden and maximizing the efficiency of storage sites used for the final disposal of spent fuel has been proposed. In this procedure, fission products (highly mobile and producing heat) are collected, and uranium and TRU-RE (transuranium-rare earth) oxide are independently stored. The possibility and applicability of radiation measurement for monitoring the nuclear materials effectively throughout the process has been simulated and evaluated. For the simulation, the properties of the chemical processes were analyzed, the major radiation emitters were determined, and the production of nuclear materials by chemical reactions were evaluated. In each process, the content of nuclear material was changed by up to 20% to represent abnormal conditions. The results showed that the plutonium peak was matched with the change in the TRU content and the measured signal was changed linearly with respect to the content change of the plutonium. From the neutron measurement, a linear response of the TRU content variation was obtained. In addition, a logic diagram was developed for the nuclear monitoring. The integration of radiation detections is recommended for monitoring the process effectively and efficiently.

Airborne surveys are an essential analysis method for rapid response and contamination identification in the early event of a radiation emergency. On the other hand, airborne surveys are far from the ground, so it is necessary to convert the dose rate at a height of 1 m above the ground. In order to improve the accuracy of the analysis value, a lot of analysis of the measurement data is required. In our previous research, we developed MARK-A1, an instrument for rapid radiation aerial survey in high radiation environment, and MARK-M1, a multipurpose instrument for radiation detection. In this study, a large unmanned aerial vehicle (UAV) was used to conduct airborne surveys using three types of detectors in the Jeju Island environment. The NaI(Tl) detector uses one 3-inch scintillator (38 mm φ × 38 mm H), and the LaBr3 detector uses two 2-inch scintillators (25 mm φ × 25 mm H). The CZT detector uses a detector with dimensions of (15 mm × 15 mm × 7.5 mm). The UAV has a payload of 15 kg (J10, JCH systems Inc. Seoul, Korea). Three different detectors were operated at a constant height of 20 m, 30 m, and 50 m. The flight experiments were performed in the west near Jeju City. Dose rate conversion factors were used to convert the dose rate from the measured spectra, and hovering flights were conducted between 1 and 50 meters to derive altitude correction factors. In this paper, the data measured with each detector in the same area were compared and the differences were derived.

When the leakage of radioactive material or radiation to the environment or a concern, it is important to accurately understand the impact on the environment. Therefore, environmental effects evaluation using modeling based on meteorological data and source-term data is carried out, or environmental radiation monitoring which is an emergency response activity that directly measures dose is performed. As lessons learned from the Fukushima accident, environmental effects evaluation and modeling cannot utilize during the emergency and decision-making process for protective action for the public. Thus, rapid environmental radiation monitoring is required. In Korea, when an emergency is issued at a nuclear facility, urgent environmental radiation monitoring is conducted based on the national nuclear emergency preparedness and response plan, which can provide important information for decisionmaking on public protective actions. A review of strategies for urgent environmental radiation monitoring is important in performing efficient emergency responses. The main purpose of urgent environmental radiation monitoring is to gather data for decisionmaking on public protective actions to minimize the damage from the accident. For effective data collection and distribution, support from the national and local government and local public organizations and radiation expertise groups, and nuclear facility licensee are required. In addition, an emergency environmental radiation monitoring manual is required to immediately perform environmental monitoring in an emergency situation. The manual for emergency monitoring should include the activities to be conducted according to the phases of the emergency. The phases of the emergency are divided into pre-leakage, post-leakage, intermediate, and recovery. The reasons for establishing strategies are government and public information, the implementation of urgent population protection countermeasures, predicting and tracking plume trajectory, and detection of any release, the protection of emergency and recovery workers, the implementation of agricultural countermeasures and food restrictions, the implementation of intermediate- and recovery-phase countermeasures, contamination control. Besides meteorological data, ambient dose rate and dose, airborne radionuclide concentration, environmental deposition, food, water, and environmental contamination, individual dose, and object surface contamination data are also required for making information for the public.