Radiological environmental impact analysis of the uranium mining site in Mika, Nigeria using time series forecast model.

This study employs time series forecasting, specifically Seasonal Auto-Regressive Integrated Moving Average, to predict the radiological impact of uranium mining in Mika, Nigeria. By utilizing meteorological data to model the dispersion of radioactive emissions to receptors, allowing for a comprehensive assessment of potential health and environmental consequences. The study observed a slight change in the Total Effective Dose Equivalent (TEDE) at the nearest residence northeast receptor between the actual and the forecasted data. The findings could be largely because of the basement complex rock formations that characterized the Mika region. The study recommend proper monitoring and evaluation should be done before full-scale mining can be carried out. However, the TEDE is generally below the International Atomic Energy Agency recommended level of 1 mSv per y for public exposure. The research demonstrates the significance of predictive modeling in managing and mitigating the radiological risks associated with uranium mining activities. Findings contribute to informed decision-making and sustainable resource extraction practices in Mika, Nigeria.

Consequence assessment of hypothetical urban radiological dispersal device incident in Korea.

Radiological Dispersal Devices (RDDs) are designed to disperse radioactive material over a wide area, leading to significant consequences to the environment and public health. This paper discusses the radiological effects of a potential RDD detonation containing 137Cs and 241Am in the commercial area of Busan, South Korea. The assessment, conducted with HotSpot Health Physics and RESRAD-RDD codes, found that summer had the most significant impact, with a maximum total effective dose equivalent (TEDE) of 280 mSv at 100 m and this decreased to 1 mSv at 4.5 km from the detonation point within the time interval of 35 min.

Comparative Analysis of Emergency Planning Zone and Control Room Habitability for Potential Nuclear Reactor Deployment in Ghana.

Following the recent surge in harnessing clean energy sources to fast-track carbon neutrality, renewable and nuclear energies have been the best-rated sources of clean energy. Even though renewable energy presents an almost insignificant risk to public health and the environment, they are insufficient to support the growing demand for the high energy required for industrialization. Despite the competitive potential of nuclear energy to meet these demands, public concerns about its safety have significantly hindered its mass deployment in developing countries. Therefore, one of the primary considerations in commissioning a nuclear power plant is the establishment of emergency planning zones based on the reactor type and other siting criteria. Based on Ghana's reactor type assessment (RTA), four reactor designs were considered in this study which are APR1400, HPR1000, VVER1200, and Nuscale Power Module. Using the NRC's SNAP/RADTRAD and RASCAL codes, this research sought to investigate radionuclide doses released at the Exclusion Area Boundary (EAB), Low Population Zone (LPZ), Control room (CR), and the 16 km recommended public safe zone during Fuel handling Accidents (FHA), Rod Ejection Accident (REA), and Long-Term Station Blackout (LTSBO). The results revealed that reactors' power contributed to the source term activities and offsite consequences during REA and LTSBO, while FHA was predominantly affected by the number of fuel assemblies and a fraction of damaged fuel. Additionally, the accidents considered in this study followed a similar trend of impact in decreasing order of reactor power and the number of fuel assemblies; APR1400 < VVER1200 < HPR1000 < Nuscale. Nevertheless, all the doses were within regulatory limits.

Radiological Dose Assessment to Members of the Public Using Consumer Products Containing Naturally Occurring Radioactive Materials in Korea.

Various products containing a small number of added radionuclides are commonly available for use worldwide. However, frequent use of such products puts the public at risk of radiation exposure. In this study, dose assessments to members of the public using consumer products containing naturally occurring radioactive materials (NORMs) were conducted for various usage scenarios to evaluate the external and internal exposure dose. Data for this study were obtained from previous literature and were statistically analyzed using Boxplot to determine the input data for assessment. A normalized value of activity concentration was used for dose evaluation. In addition to other external and internal dose calculation codes, analytical calculations were used to perform age-dependent. Based on analytical calculations, the highest total effective dose equivalent (TEDE) received from necklace products at the upper whiskers with an activity concentration of 4.21 Bq/g for 238U, 24.4 Bq/g for 232Th, and 0.55 Bq/g for 40K for various age groups is 2.03 mSv/y for 1 year old, 1.24 mSv/y for 10 years old and 1.11 mSv/y for adult, which are above the international commission for radiation protection (ICRP) recommended public dose limit of 1 mSv/y. Results of external and internal exposure dose obtained using Microshield code, IMBA code and Visual Monte Carlo (VMC) code are all below the recommended public dose limit of 1 mSv/y.

POTENTIAL ENVIRONMENTAL HAZARD TO THE PUBLIC FROM THE OPERATION OF URANIUM MINING AND MILLING FACILITY.

Mining and milling processes could cause potential radiological exposures to the public. The objective of this study was to estimate the off-site radiological doses expected to be received by the public as a result of uranium mining and milling activities at Mkuju River Project in the United Republic of Tanzania. MILDOS-AREA was used to estimate off-site doses along with RESRAD-OFFSITE for comparison and verification. Since the mining has not yet started, the conceptual scenario was chosen. Using the concept of the most exposed individual, the location of the nearest residence (receptor) was chosen at 2.5 km from the site with other receptors being the fence boundary and grazing area being at 1.0 and 1.8 km, respectively. Yellowcake stack (point source), ore pad and two tailing piles where each had an area of 2.5 × 105 m2 were chosen to be the source of radiological contamination. The radiological source term was obtained from the concentration of 226Ra and 232Th in soil obtained from the previous studies of environmental impact assessments. Meteorological and site-specific data were used for this analysis. The estimated total effective dose equivalent (TEDE) for the nearest residence which was calculated by MILDOSE-AREA ranged from 2.5 × 10-2 to 4.45 × 10-2 mSv/y during the operation of 13 y. The result of RESRAD-OFFSITE ranged from 7.19 × 10-2 mSv/y for the first year to 7.43 × 10-2 mSv/y in the final year. This implied all the estimated TEDEs were below the dose limit and dose constraint of 1 and 0.3 mSv/y, respectively, as suggested by the International Atomic Energy Agency. Hence, it was found that there was no potential radiological concern of uranium mining at Mkuju River Project. It was found that using MILDOS-AREA it is possible to estimate dose at different distances from the facility. Therefore, this study apart from estimating the off-site doses, it can be used for planning of public and social premises before the commencement of the project. That is the distance from the facility where the public should be located as well as other locations for social activities.

OFF-SITE RADIOLOGICAL DOSE ASSESSMENT IN A SEVERE NUCLEAR ACCIDENT OF APR1400.

Shin Kori unit 3 of Korea Hydro and Nuclear Power Co. is the pressurized water reactor of advanced power reactor 1400 (APR1400) in the Republic of Korea. A hypothetical accident was assumed for Shin Kori unit 3 to perform the time-dependent dose calculations along with the release rates of radionuclides to the environment. In order to assess the accident scenarios, Radiological Assessment System for Consequence Analysis code was used, which is a set of tools for emergency response applications developed by US Nuclear Regulatory Commission. A straight-line Gaussian model was used for the near-field atmospheric calculations and a Lagrangian Gaussian puff model was used for the far-field simulations where released radioactive materials to the environment were transported, dispersed and deposited. In this study, long-term station blackout in spring, summer, autumn and winter season was considered in 2016-2018 based on reactor condition and seasonal effects. It was found that the worst season is the spring and the worst scenario found during the evening time of spring in 2017. The calculated maximum values of total effective dose equivalent (TEDE) and thyroid committed dose equivalent (CDE) are 22 mSv and 390 mSv, respectively, around 5 km of precautionary action zone (PAZ) in 2 days after the accident. According to Korean regulations on urgent public protective actions, for indoor sheltering, the criteria are 10 mSv in 2 days. For public evacuation 50 mSv in 1 week and iodine prophylaxis should be introduced if thyroid protection level is 100 mSv. Calculated values of TEDE are more than double and thyroid CDE is almost four times in the PAZ compared with Korean regulations; hence, it was found that indoor sheltering and supply of iodine prophylaxis should be executed for short/mid-term protective measures. In this situation, indoor sheltering should be decided by off-site emergency management center, which was accountable for emergency decision-making process in nuclear accident under nuclear safety and security commission in Korea.

Occupational ALARA Planning for Reactor Pressure Vessel Dismantling at Kori Unit 1.

Assessing workers' safety and health during the decommissioning of nuclear power plants (NPPs) is an important procedure in terms of occupational radiation exposure (ORE). Optimizing the radiation exposure through the "As Low As Reasonably Achievable (ALARA)" principle is a very important procedure in the phase of nuclear decommissioning. Using the VISIPLAN 3D ALARA planning tool, this study aimed at assessing the radiological doses to workers during the dismantling of the reactor pressure vessel (RPV) at Kori NPP unit 1. Fragmentation and segmentation cutting processes were applied to cut the primary component. Using a simulation function in VISIPLAN, the external exposure doses were calculated for each work operation. Fragmentation involved 18 operations, whereas segmentation comprised 32 operations for each fragment. Six operations were additionally performed for both hot and cold legs of the RPV. The operations were conducted based on the radioactive waste drum's dimensions. The results in this study indicated that the collective doses decreased as the components were cut into smaller segments. The fragmentation process showed a relatively higher collective dose compared to the segmentation operation. The active part of the RPV significantly contributed to the exposure dose and thus the shielding of workers and reduced working hours need to be considered. It was found that 60Co contained in the stainless steel of the reactor vessel greatly contributed to the dose as an activation material. The sensitivity analysis, which was conducted for different cutting methods, showed that laser cutting took a much longer time than plasma cutting and contributed higher doses to the workers. This study will be helpful in carrying out the occupational safety and health management of decommissioning workers at Kori NPP unit 1 in the near future.

EMERGENCY EVACUATION SIMULATION FOR A RADIATION DISASTER: A CASE STUDY OF A RESIDENTIAL SCHOOL NEAR NUCLEAR POWER PLANTS IN KOREA.

Ensuring evacuation of people from a building in a fast and secure manner is of great significance in the event of emergency situations. This study aimed at evaluating the level of evacuation preparedness and movement of residents at the KEPCO International Nuclear Graduate School (KINGS) in the event of a nuclear emergency. Evacuation times from KINGS after a nuclear disaster at Shin Kori nuclear power plant (NPP) were estimated using Pathfinder. Four scenarios of night and day time by assuming the normal and worst scenarios were simulated. With regard to worst scenarios, the times estimated for residents to gather and leave the assembly point for the night time scenario were estimated to 22~23 min, whereas 38~39 min were calculated for the crowd to leave the assembly point. The results of this study can be used by emergency planners when planning for evacuation from a residential building nearby NPP.

TRANSBOUNDARY RADIOLOGICAL EFFECTS OF A HYPOTHETICAL NUCLEAR ACCIDENT IN NORTHEAST ASIA.

Offsite radiological consequence investigation using computerized software has been considered as an important quantitative risk communication in order to recognize and discuss public concerns about nuclear safety and health risk in case of hypothetical nuclear accidents around specific nuclear power plants (NPPs), with guideline of lessons learned from previous nuclear disasters. In this study, Northeast Asia nuclear accident simulator (NANAS) developed by Nuclear Safety and Security Commission (NSSC) in Korea was used to quantify the offsite radiological consequences from Haiyang unit 1 NPP in China and to examine the emergency protective measures for the public around regions of Korea as NPPs operating in Northeast Asia countries contributed to about 25% of the industry. Broad simulations of radiological source term estimation, atmospheric dispersion analysis and radiation dose assessment to the public have been performed in case of hypothetical nuclear accident involving source term of radionuclides release taken from Fukushima accident.

Development of Northeast Asia Nuclear Power Plant Accident Simulator.

A conclusion from the lessons learned after the March 2011 Fukushima Daiichi accident was that Korea needs a tool to estimate consequences from a major accident that could occur at a nuclear power plant located in a neighboring country. This paper describes a suite of computer-based codes to be used by Korea's nuclear emergency response staff for training and potentially operational support in Korea's national emergency preparedness and response program. The systems of codes, Northeast Asia Nuclear Accident Simulator (NANAS), consist of three modules: source-term estimation, atmospheric dispersion prediction and dose assessment. To quickly assess potential doses to the public in Korea, NANAS includes specific reactor data from the nuclear power plants in China, Japan and Taiwan. The completed simulator is demonstrated using data for a hypothetical release.

Development of nuclear emergency exercise programme (NEEP) in Korea.

The nuclear emergency exercise programme (NEEP) is a PC-based application intended for design and planning emergency preparedness and response (EP&R) exercises for a potential nuclear emergency in Korea. The application programme allows EP&R staff to create and edit exercise scenarios based on information customised for a specific nuclear power plant's emergency plans. NEEP includes the following features: (1) step-by-step guide to developing new exercise scenario according to emergency alarm level and potential accident type, (2) database of specific plant's field exercise scenarios that can be easily modified by users, (3) generating master scenario events list and messages of exercise participants and (4) allowing the quantitative evaluation of exercise participants from the view of exercise objectives and evaluator guides. NEEP also features tools for queries, reports and visualisation that can be used to create documentation during the scenario planning and exercise evaluation processes.

Development of realistic RDD scenarios and their radiological consequence analyses.

The terrorist attack on September 11, 2001, brought about deep interest on the radiological dispersal device (RDD) and the malevolent radiological event. In this study, realistic potential scenarios using RDD were developed. Among those probable radionuclides, (137)Cs and (241)Am were selected to simulate the radiological effects caused by dirty bomb. Their radiological consequences were assessed in terms of total effective dose, projected cumulative external and internal dose and ground deposition of radioactivity.