With the rapid development of modern science and technology, the radiation field, an invisible and intangible pollution source, has attracted increasing attention from all walks of life, which is called "invisible killer" electromagnetic radiation.
With the rapid development of modern science and technology, the radiation field, an invisible and intangible pollution source, has attracted increasing attention from all walks of life, which is called "invisible killer" electromagnetic radiation.Today, more and more electronic and electrical equipment are put into use, making electromagnetic waves of different frequencies and energies fill every corner of the earth and even the broader space.For the human body, a good conductor, electromagnetic waves will inevitably pose a certain degree of harm.
Electromagnetic radiation source
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Generally speaking, radar system, TV and radio transmission system, radio frequency induction andMedium heatingEquipment, radio frequency and microwave medical equipment, various electroprocessing equipment, communication transmitting stations, satellite earth communication stations, large power stations, power transmission and transformation equipment, high-voltage and ultra-high voltage power transmission lines, subway trains and electric trains, as well as most household appliances are all sources of electromagnetic radiation that can produce various forms, different frequencies and different intensities.
Radiation field visualization platform
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The radiation field visualization platform integrates the virtual reality technology and radiation protection technology. The development of the platform aims to simulate the complex environment of the radiation field with computers, carry out virtual experimental operations and real-time calculation and display of data, and finally provide users with the obvious exposure of the radiation field at the computer terminal.Radiation field visualization, with its intuitiveness, interactivity, high transparency, strong operability and other characteristics, can become one of the effective means to reduce the radiation dose of nuclear power plant workers.
The research goal of radiation field visualization platform is to use desktop virtual reality technology, with the help of keyboard, mouse and other input devices, to observe the virtual scene of radiation field changes in the nuclear power plant building within 360 degrees through the computer screen, and according to the real-time situation in the maintenance process (such as adding or removing shields, etc.)Calculate the dose rate and exposure of different components and pipelines of the nuclear power plant, so as to command the staff and complete a series of specific tasks when the working conditions change.In general, this system will use human-computer interaction interface to reflect the changes of radiation field in the plant in real time, and estimate the radiation dose received by the staff, and finally provide the best maintenance plan for the maintenance work through the visual interface to reduce the amount of radiation for the staff and save production costs.
The radiation field visualization platform can not only optimize the design of radiation protection and reduce the dose received by staff in actual operation, but also be used for training staff before actual operation to save experimental funds and improve the training effect.In addition, the radiation field visualization platform also has wide application space and broad application prospects in many aspects, such as staff's learning of radiation protection related laws and regulations, calculation of dose distribution in the radiation space, and ALARA (as low as reasonably achievable) design analysis.
However, how to realize the simultaneous calculation of the dose received by the staff in the virtual world and the actual operation process (quickly and accurately calculate the dose rate) is the difficulty of the platform.The methods commonly used for radiation dose calculation include Monte Carlo method and point kernel integration method.Monte Carlo method is one of the mature methods to solve the radiation shielding problem under complex geometric conditions on the computer, but this method is slow, and some dose calculations often take hours or even days to run once.The other method is the point kernel integration method. Compared with the Monte Carlo method, it is not only not limited by the space size and the thickness of the shield, but also has less machine time and higher calculation efficiency.At present, QAD-CG program is the common point kernel integration program in the world.This program calculates the penetration behavior of particles in the geometric space by using the point kernel integration method, forms the actual required geometric space by combining and matching, and uses the ray tracing method to improve the calculation speed of the optical distance of particles passing through the geometric space, and can calculate the fluence rate, dose rate and heat release rate caused by the volume source at each point in the space.Therefore, it is feasible to use the point kernel integration program to study the visualization of radiation field.[1]
research status
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Virtual reality technology has been widely and deeply applied in the field of radiation protection abroad, including ALARA design analysis, staff training, calculation and display of dose distribution in the radiation field, etc.
(1) ALARA design analysis
NASA has developed a virtual reality system for the optimal design of radiation protection in the space capsule.The system achieves optimization by changing the shielding design scheme in the capsule, and can calculate the change of radiation field in the capsule in real time.This design reflects the ALARA principle, that is, through dose prediction and shielding optimization design, the exposure dose to staff in a task is reasonable, feasible and as low as possible.
(2) Staff training
Spain has developed a set of CIPRES (Interactive Calculations of Radiological Protection in a Simulation Environment) system specifically for the refueling process of the Confrentes nuclear power plant. This virtual reality system can calculate the dose of the entire refueling process.CIPRES system simulates the operation steps in the refueling process of nuclear power plant, analyzes these steps and input data, calculates the dose distribution in key areas, and establishes corresponding calculation models accordingly.The purpose of this system is to reduce the operation time and finally achieve the goal of controlling the radiation dose by training the refueling staff before actual operation to become proficient in the operation process.
The European Nuclear Energy Agency, i.e. ENEA, has applied virtual reality technology to the decommissioning of nuclear facilities. In this task, some contaminated glove boxes need to be removed. Therefore, ENEA has developed a virtual reality system to simulate the removal device, and used this system to conduct pre work training for operators.
Belgium developed3D visualizationThe tool VISIPLAN 3D ALARA Planning Tool is used for training before operation. The system can simplify modeling for real scenes and calculate dose distribution, and has made good progress.[2]
(3) Dose distribution calculation
South Korea has developed a dose distribution simulation system for nuclear power plants using JAVA programming language and virtual reality technology. This system can successfully predict the exposure dose of virtual workers by simulating the work in the radiation environment in the virtual scene, and display the radiation hazard area in a special way through three-dimensional visualization,The system can effectively prevent the workers in the radiation area from receiving unnecessary radiation.
Japan has developed a set of virtual reality platform for radiation protection for the maintenance process of nuclear power plants. This platform mainly studies the visualization of three-dimensional radiation fields, and uses color graphical interfaces to represent different degrees ofRadiation dose rate, which can reflect the dose rate and exposure of different pipes and components in the nuclear power plant.The disadvantage of this system is that it can only provide local radiation conditions, and cannot show the dose rate of the whole radiation field space.
Radiation protection of nuclear power plant
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Radiation protection of nuclear power plant is one of the important links to ensure the safety of workers. The goal of safe operation of nuclear power plant is to provide radiation protection for workers under normal operating conditions and expected operating event conditions, so that their exposure dose does not exceed the occupational exposure dose limit given in the standard under any circumstances.Therefore, dose limits are not only biological and medical values, but also closely related to society, economy and people's acceptance of risks.After taking economic and social factors into account, all exposures should be kept at the lowest level that can be reasonably reached, and the dose received by individuals should not exceed the design limit.On the basis of the safe operation of nuclear power plants, the economic benefits of nuclear power plants are also an important factor that must be considered. For safety reasons, nuclear power plants have become the opposite of economy due to large capital investment and high maintenance costs. How to unify the safety and economy of nuclear power plants is also currently developingThird generation nuclear power plantThe goal to strive for.[3]
According to statistics, the daily activities of domestic nuclear power plant staff during normal operation account for about 20% of the total annual dose;During the overhaul of nuclear power plants, the dose received by the staff accounts for about 80% of the total annual dose.Radiation protection during overhaul mainly depends on shortening the stay time of workers in the radiation area to reduce the exposure dose.However, many studies have shown that the exposure dose is not only related to the residence time, but also to the distance between the workers and the radiation source.Therefore, under the condition that most of the current protective facilities and means in China are not complete, there is no doubt that the risk of workers being exposed, the cost of maintenance and the capital investment in the construction of the experimental platform have increased.At present, the cutting-edge virtual reality technology in the world can calculate the dose rate and exposure of different components and pipelines of nuclear power plants by simulating the real environment, and provide the best maintenance route in real time in the form of visual graphics, effectively reducing personal exposure dose and operating costs.[4]
