The fourth scientific and technological revolution in the middle of the twentieth century marked the beginning of globalization and application of the latest technologies. Innovations gradually covered all spheres of public life. Today we watch 3D movies, take photos using drones, travel around different universes using virtual reality. This has become a habit for many people.
Up-to-date technologies will also enter the nuclear sphere in the near future not as an innovation and not as a separately developed project, but for everyday use. The introduction of innovations in the nuclear industry was caused not only by scientific and technological progress, but also by nuclear accidents at the Three Mile Island, Chornobyl, Fukushima-1 nuclear power plants. The editors of the Uatom.org website tell what kind of nanotechnologies have been widely used in the nuclear area.
Use of Robots to Eliminate Accident Consequences at Chornobyl and Fukushima-1 NPPs
For the first time, term “robot” was used in 1921 in play “R.U.R” by Czech writer Karel Capek to designate artificial creatures that look like people. In the nuclear area, the Model-1 copying manipulator (Master-slave Manipulators, MSM) developed in 1949 to provide personnel work with radioactive pharmaceuticals is considered to be the first robot.
Manipulators in the nuclear field are commonly used for decommissioning and dismantling of nuclear installations. Thus, German company «Wälischmiller Engineering» has been developing nuclear technologies since 1950. Their waterproof manipulators designed to dismantle nuclear reactors were first developed in 1990. Since that time, they contributed to dismantling of three German NPPs: Greifswald (1995-1998), Rheinsberg (1995-1998), Obrigheim (2015-2016). In addition, their manipulators can be used in maintenance of nuclear installations and in the event of emergencies.
In Ukraine, the use of robots started in 1986 to mitigate Chornobyl accident consequences. The first robot, which worked for almost a year, was an independently developed children’s tank with a screwed-on dosimeter and a flashlight, which was controlled using a cable of the remote control. During this time, about 15 modular robots were involved. Heavy (technological) robots, in particular Mobot-Ch-KhV, Klin-1, STR-1, were designed to clean and decontaminate the territory, and light reconnaissance robots, including RR-G1, RKK -1, RDK, RDG were used to study the radiation situation in the Sarcophagus premises.
Since 1990, Intersectoral Scientific and Technical Center “Shelter” of the National Academy of Sciences of Ukraine, jointly with the Kurchatov Institute of Atomic Energy started activities to develop remotely controlled units (RCUs) that can be operated at ChNPP-4. In four years, three RCUs were developed: TR-3 (for video reconnaissance of the Shelter premises), TR-4 (to sample radioactive materials inside the Shelter and assess the amount and composition of fuel-containing materials), TR-7 (to apply dust suppressants). The design and manufacturing of RCUs for sampling radioactive aerosols was also started in the Nuclear and Radiation Safety Department of the Institute for Safety Problems of Nuclear Power Plants in 2013.
Supporting Ukraine in the fight against Chornobyl accident consequences, the US Department of Energy and the US National Aeronautics and Space Administration (NASA) funded the development and manufacturing of the Pioneer radiation-resistant mobile diagnostic robot, which was used to create three-dimensional digital reconstructions of the environment, create three-dimensional databases, integrity assessment of Shelter structures, take samples from the floor and walls.
Robots are used at the Fukushima-1 NPP to accelerate decommissioning of the NPP, conduct studies, decontaminate areas with high radiation levels and remove fuel debris from the reactor pond or the reactor pressure vessel, as well as to develop technologies for inspecting the inner part of the reactor containment. In addition, within the cooperation with local and international companies, robots are used for further joint projects. In particular, the company divides the use of robots into two types: those used on the ground (zero) floor and above the first floor of the nuclear power plant.
The ground floor uses 7 types of robots developed by Toshiba, Hitachi GE, ATOX, Topy Industries. In particular, to study the outer lower surface of the suppression chamber, the wall between the reactor and the turbine hall, ventilation pipes; to measure the water level inside the suppression chamber; to detect leaks in the reactor containment, etc. Above the NPP first floor, 19 types of robots are used to:
- detect a radiation source: Kanicrane (Hitachi GE), Rosemary, Sakura (Chiba Institute of Technology, Hitachi GE) robots;
- decontaminate places with high radiation levels. For example, the Toshiba robot decontaminates using dry ice, while the Hitachi GE robot decontaminates using a high-pressure water jet. The MEISTeR robot developed by the Mitsubishi Heavy Industries uses shot blasting for decontamination;
- clean protective screens and iron plates: TEMBO robot developed by the Mitsubishi Heavy Industries;
- inspect and assess the condition of certain equipment. For example, Hitachi GE has developed a shape-shifting robot to examine the internal part of the reactor containment. It first takes a tubular shape to cross the narrow tube and reach the internal part of the containment, and then takes the U-shape;
- collect garbage: ASTACO-SoRa robot by Hitachi GE;
- remove disturbances: Warrior by iRobot;
- conduct studies. For example, a robot by Hitachi GE uses 3D laser scanning to obtain data inside reactor vessels.
So, as you can see, robots at nuclear power plants has become widespread mainly for decommissioning of nuclear power plants. Analyzing the use of robots at the Chornobyl and Fukushima-1 nuclear power plants, we can summarize that it is necessary to provide the use of different robots and with different access types. This will contribute to overcoming accident consequences avoiding exposure of NPP personnel. The use of robotics at nuclear power plants will help in conducting studies and developing an action plan in case of accidents or emergencies.
Use of Immersive Technologies at Nuclear Power Plants: Virtual and Augmented Reality
It is necessary to start with the fact that the Institute of Energy Technologies has been operating in the Norwegian city of Halden since 1948, whose one of the tasks is to develop the latest technologies in the field of virtual reality, augmented reality, and digitalization to ensure nuclear safety. There is a Virtual Reality Center, whose activities are aimed at designing workplaces, safety training and optimizing work for critical activities for safe operation of installations. The Virtual Reality Center can be used to model the control center and simulate personnel actions in the digital twin of the controlled installation.
The most common use of virtual reality technology is to train personnel for any possible scenarios of nuclear reactor operation: from minor occurrences to emergencies.
The first nuclear power plant in the world to equip a virtual reality training room for control room operators was the Loviisa Nuclear Power Plant in Finland. The project was implemented by the Varjo company, which developed a virtual reality helmet with built-in gaze tracking. “Trainers can follow trainees’ eye movements and also give them tasks. If a trainee needs to check a certain value from the main control panels using real-time gaze data in a virtual reality environment, a trigger can be defined that will report that the trainee has not completed the task after reading the instructions during a sufficient period. That is, this function allows analyzing operator behavior and get information about how well the user interfaces work. 90% of Loviisa NPP personnel have been trained using virtual reality and are ready to implement it for training and daily use.
The Technology Institute of the University of Ontario in Canada operates a virtual nuclear reactor simulator to train emergency response personnel regarding basic knowledge on control room operation during emergencies at nuclear power plants. In real time, experts are in the control room to operate the reactor in different scenarios. During the exercise, it is planned to stop simulator operation to analyze the behavior of participants and provide the information on possible actions in emergencies beyond the site.
Nuclear reactor supplier Hitachi Nuclear Energy has been using virtual reality since the end of 2021 to train nuclear power plant personnel for operation scenarios arising during downtime or maintenance. With the Nuclear Virtual Reality Solution (VRS) tool, you can model various types of power plants, including boiling water reactors, pressurized water reactors, and fuel flow technologies.
In addition to training and education of nuclear power plant workers, the virtual reality technologies can be used in the design and operation of nuclear reactors.
The Institute of Nuclear Energy Safety Technology of the Chinese Academy of Sciences has developed a virtual nuclear power plant (Virtual4DS): “integrated simulation platform covering the NPP environment, based on a digital reactor composed of digital traffic, digital meteorology, and data on processes in the earth’s crust.” The virtual nuclear power plant can be connected to the new nuclear power plant management system to simulate operation, train personnel, and model an emergency to test the effectiveness of an emergency action plan for workers. “The Virtual4DS performs the following tasks: reactor design and operation modeling, accident modeling and warning, full-scale radionuclide migration and environmental impact assessment, public health risk assessment.”
In 2019, developers from the Japan Atomic Energy Agency and the Tokyo Electric Power Company released a virtual reality kit that can take people inside the Fukushima radioactive reactor. Due to the information gathered, scientists and engineers can learn what kinds of robots can be used to study radioactive debris inside these reactors.
One of the important stages in ensuring safety of nuclear installations is the design stage. Its obligatory component is validation, which determines whether the control room works as intended. Virtual reality allows checks, preliminary estimates, and early correction of errors before design implementation. The integrated system validation of NPP control rooms was implemented by already mentioned company Varjo.
The nuclear industry uses also virtual reality in turbine maintenance and inspection training. It is less expensive than to develop physical models, and with the help of the latter, engineers cannot see different components of a turbine or engine in action. In addition, virtual reality contributes to nuclear fuel management training. Workers can learn how to properly manage fuel without damaging the reactor structural integrity and prevent radiation effects. In the last decade, virtual tours to nuclear power plants have become popular, which helps engineers better navigate a nuclear power plant, and visitors can familiarize with the structure of a nuclear power plant, its control room, located reactors, and distribution station, etc.
In Ukraine, the virtual reality technology was used to decommission three not damaged ChNPP units. The Chornobyl Decommissioning Visualization Center project was launched in 2006 under the support of the Norwegian Ministry of Foreign Affairs, and the following year, as part of the pilot version of the project, a virtual three-dimensional environment was visualized, and dismantling procedures were developed and recorded. The developed software supported only the basic functions for dismantling procedures.
However, until 2012, the project was slowly implemented due to the need to conclude an intergovernmental agreement on cooperation between Norway and Ukraine. On 30 November 2012, the intergovernmental agreement was signed in Oslo, and in 2016, the Chornobyl NPP Decommissioning Visualization Center was finally established to introduce the latest virtual reality and 3D modeling technologies at ChNPP. After training, ChNPP experts develop a detailed 3D model of the object where the work will take place. The model includes the exact location of equipment, personnel and tools in the room. After that, on the basis of surveys, a cartogram of radiation contamination is entered into the model.
As part of the project, gamma radiation fields were visualized in the exclusion zone. Based on the measurement data, occupational exposure doses were calculated to determine the standards that personnel can receive when they are in a radioactively contaminated area. This serves to further minimize the risks of radioactive contamination and optimize personnel work. The project allows workers to plan work tasks related to facility dismantling, develop the necessary documents and train during the decommissioning stage.
The introduction of the latest technologies at the Chornobyl nuclear power plant will contribute to planning of decommissioning, rapid storage and presentation of the information on ChNPP facilities, during engineering, radiation surveys and dismantling, in the management of radioactive materials, for personnel training, etc. The implemented project is the training of personnel before the decommissioning stage in order to reduce the workload, identify possible radiation exposure and improve nuclear safety.
So, we can summarize: most often, the virtual reality technology is used to train nuclear power plant workers for gaining practical experience that cannot be reproduced through physical models or during operation of a power plant, prepare for emergencies and evaluate actions in emergencies. The environment modeled using virtual reality will help in maintenance of nuclear reactors, nuclear fuel management and will contribute to the preparation of decommissioning. In addition, virtual reality can serve to study radioactive fragments inside fragments.
Radiological survey of territories and data collection using drones
In the nuclear area, drones or UAVs are usually used for radiological survey of territories and determination of the ambient equivalent dose rate (EDR) of gamma radiation. First, drones are equipped with radiation detectors, cameras and GPS receivers. During takeoff, the drone synchronizes with the ground station using GPS coordinates and transmits real-time measurement data that are then stored in the on-board system. It is possible to visualize the radiation situation in the surveyed areas after the drone has landed by combining photographic and geographic information with radiometric data.
After the accident at the Japanese Fukushima nuclear power plant in 2011, a high level of radiation contamination posed a threat to people, nearby areas and further studies, in particular monitoring of radiation indicators. This led to the use of the latest technologies. Thus, during 2012-2020, Fukushima workers and IAEA jointly developed the technology of radiation reconnaissance using drones. Remote monitoring of radiation levels is carried out in the areas of Fukushima Prefecture using unmanned aerial vehicles equipped with radiation detectors, cameras and GPS devices. The data collected by drones can be used to assess potential radiation risks and justify related plans and strategies for land remediation, decontamination of effluents and nuclear waste management in Japan.
An UAV-based LiDAR and multispectral images were used to detect radioactive waste disposal sites in the Chornobyl exclusion zone. This method involved generating a digital terrain model and a 3D vegetation map based on the data and tree characteristics, including tree density, height, and tree species. After that, histograms and LiDAR metrics were developed, using which machine random forest classifier training is carried out. According to the results of the study, the use of a UAV-based LiDAR and multispectral images showed the discovery of unknown radioactive waste disposal sites, which is confirmed by drilling of 38 wells where previously disposed nuclear materials were found.
Drones in the nuclear industry can be used not only for radiological surveys, but also for more routine tasks at nuclear power plants, such as equipment testing, reading of sensors, data collection, etc.
Using artificial intelligence and machine training algorithms, researchers at the Idaho National Laboratory have developed a Remotely Operated Unmanned Navigation Drone (ROUNDS) program to provide autonomous operation within a nuclear power plant through advanced image analysis and QR code reading. By scanning QR codes at nuclear power plants, the drone determines its location and thus, performs the task prescribed by the code, such as collecting data or checking sensor indicators. The received information is transmitted to the controller on a stationary computer, and after completing all the tasks, the drone will return to the charging pad. The ROUNDS software allows drones to move quickly in the confined space of industrial rooms, cover large distances in a short period. Having developed a program for remotely controlled unmanned navigation of drones, researchers sought to use them to inspect the territory of nuclear power plants, control stocks of nuclear materials, collect data and check equipment.
In addition to the benefits of using drones, there are hazards and risks that threaten the nuclear safety of nuclear power plants. In particular, back in 2014, it was known about the unauthorized flight of drones over seven nuclear power plants in France, and in 2016 about the threat to nuclear safety at the Savannah River Site (SRS) in the United States. Two months later, eight drones were found at the site by the security service. In 2016, a drone operator flew it over the cooling tower of the Liebstadt nuclear power plant in Switzerland. By posting a video of the flight, he made people wonder how easily a drone could get into a nuclear power plant. In 2018, Greenpeace activists threatened nuclear safety of nuclear power plants. To draw attention to environmental problems and lack of physical protection around the nuclear power plant, they launched a drone into a French nuclear power plant, and the following year, using a drone, they dropped a smoke bomb over a nuclear facility where irradiated fuel was stored.
As a result of the increase in the number of drones flying over nuclear power plants, the US Nuclear Regulatory Commission together with the Sandia National Laboratory, initiated a technical analysis in 2020 to assess the threat of flying drones. The Commission stated that the use of unmanned aerial vehicles does not pose a threat to US nuclear power plants, in particular, the information received cannot lead to radiological sabotage, theft or leakage of special nuclear material (reactor fuel).
The use of 3D printing to manufacture spare parts for nuclear reactors at NPPs
Siemens was the first company to use 3D printing technology to manufacture spare parts for nuclear power plants. In 2017, technologists created an impeller with a diameter of 108 mm for a fire-fighting water pump at the Krsko NPP in Slovenia. The original part was in operation since the commissioning of the nuclear power plant in 1981. To do this, Siemens technologists developed a digital twin of the part and then manufactured the part using an additive manufacturing process. It should be noted that to provide suitability of using the printed part at NPP, tests were carried out over several months, they were preceded by studies of material by an independent institute, as well as checks using computed tomography.
In 2022, American company Unsafe Nuclear Corporation (USNC) obtained a license to use a new method for 3D printing of parts for nuclear reactors developed by the Oak Ridge National Laboratory of the US Department of Energy. Complex shape parts made of refractory materials that are resistant to extreme heat and degradation are printed using additive manufacturing inkjet printing combined with chemical vapor infiltration – a ceramic engineering process. USNC chose high temperature and radiation resistant silicon carbide as the material. It should also be noted that before this technology development, manufacturing of spare parts made of this material for the reactor was laborious and expensive. The new technology will make manufacturing reactor parts more efficient, simpler and cheaper.
In the same year, using 3D printing technology, in close cooperation with plant operators Teollisuuden Voima Oyj (TVO) and OKG, Westinghouse developed the StrongHold AM nuclear waste filter. The 3D-printed filters were installed at two BWR (boiling water reactor) units of the Olkiluoto 2 nuclear power plant in Finland and Oskarshamn 3 in Sweden. This innovation will prevent debris from entering fuel assemblies and potential cladding damage, which can lead to unplanned and costly downtime.
It is only beginning of applying the 3D printing technology at nuclear power plants. However, the introduction of a new method is very important for the nuclear industry, as it will help to speed up and reduce the cost of manufacturing spare parts and components. In addition, this will contribute to the creation of twin parts, whose manufacturers have already closed their factories.
Globalization, digitalization – all these are inevitable processes of the 21st century. Modernization has covered all activity areas and innovations have become the driving force for change and development of a post-industrial society. In the nuclear field, the latest technologies are not only an important tool for production automation or gaining access to hard-to-reach places. Innovation plays an important role in ensuring nuclear and radiation safety.
As you can see, the use of robots or virtual reality is not a new phenomenon in the nuclear area, although it has not yet become widespread. Drones have been used since the Fukushima accident, and implementing 3D printing technologies just has started.
The latest technologies were most widely used during NPP decommissioning. This is not surprising, because using them it is possible to detect a radiation source without being exposed to radiation, and to decontaminate it. In addition, the use of up-to-date technologies will provide round-the-clock monitoring of NPP and its equipment state, thereby warning of the hazard of a possible radiation leak.
The introduction of the latest technologies will also contribute to training of qualified personnel who is able to gain practical experience, or retraining in the case of constructing new reactors. In addition, using new technologies, it is possible to assess the behavior of NPP personnel in the event of an emergency and develop an action plan for the future. The influence of the latest technologies on research should not be underestimated, because their use facilitates data collection and processing, thereby contributing to new projects.
However, do not forget that the use of the latest technologies will not be able to prevent hazards caused by the negligence of NPP personnel or natural disasters. In addition to the advantages of using the latest technologies at NPPs, there are disadvantages and risks, because at any time you can lose control over management and thereby endanger nuclear safety of a nuclear power plant.
Obviously, the latest technologies are the future. However, if now we consider only robotics, virtual reality, drones and 3D printing technologies, then soon a variety of digital solutions and mobile applications will be among the up-to-date technologies used at nuclear power plants, because the whole world is moving into the digital sphere, and the nuclear industry is not an exception.
The Editorial Board of the Uatom.org website