What is electron accelerator sterilization?
Electron accelerator sterilization is the use of high-energy rays generated by ionizing radiation such as x-rays, gamma rays or high-speed electron beams to process food. In the process of energy transfer and transfer, it produces powerful physical and biological effects to achieve insecticidal, The purpose of sterilizing, inhibiting physiological processes, improving food hygiene quality, maintaining nutritional quality and flavor, and extending shelf life.
Compared with the traditional cobalt source irradiation, the high-energy electron accelerator irradiation technology has distinctive characteristics mainly reflected in:
(1) Rapid irradiation. The irradiation processing time is short, for example, it takes only 1 minute to sterilize a box of products; while it may take tens of minutes to irradiate with a cobalt source.
(2) The absorbed dose is uniform. Using a dynamic conveying device, the unevenness of the product absorbed dose is <5%. One-time large batch processing can also be processed in small batches, with flexible processing methods.
(3) The product can be sealed and packaged in advance, and the product packaging box will not be opened during irradiation. It can pass quickly and safely without secondary pollution.
(4) No environmental pollution. After shutting down, there is no radiation, which is safe and reliable. However, the use of cobalt source has the problem of source waste and waste source disposal.
(5) The degradation of residual chloramphenicol in aquatic products and bee products is the only method at home and abroad.
(6) Low investment and high output.
How does an electron accelerator work?
Electron accelerator device
Electron accelerator is an electromagnetic device that uses artificial methods to make electrons in vacuum under the action of magnetic field force and electric field force to accelerate to reach high energy.
Industrial irradiation electron accelerator refers to an electron accelerator device mainly used for irradiating various materials, participating in chemical reactions, sterilizing and disinfecting and other industrial production processes.
High-energy electron beam is a commonly used source of ionizing radiation. Its interaction with matter is similar to γ-rays or X-rays. It can cause various physical, chemical, and biological effects, which are called ionizing radiation effects. The basis of this application.
Basic composition of electron accelerator
Key control, door machine interlock, beam device interlock, A signal warning device, inspection button, anti-personnel entry device, emergency stop device, dose interlock, ventilation interlock, smoke alarm
how to make an electron accelerator?
The whole linac comprises mainly E-gun, pre-buncher, buncher, and 2 accelerating columns. A disk-loaded, on-axis-coupled, 2π/3-mode type accelerating rf cavity is considered for this linac. After numerous optimizations of linac parameters, 32?MeV beam energy is obtained at the end of the linac. As high electron energy is required to produce acceptable neutron flux. The final neutron flux is estimated to be 5?×?1011?n/cm2/s/mA. Future development will be the real design of a 30?MeV electron linac based on S band traveling wave.
What is an electron accelerator used for?
Electron accelerators are the most important source of radiation and are widely used in industry, agriculture, medical and health, environmental protection and other fields. A very important industry that is the irradiation processing industry has been formed. In the development of nuclear technology application industry, accelerator is the foundation and key of the irradiation processing industry. Therefore, the production and manufacturing of electron irradiation accelerator occupies a prominent position.
electron accelerator applications
electron accelerators for industrial applications
The scanning instrument used in electron irradiation is an important device of the electron accelerator.
Industrial CT adopts electron accelerator to produce the high energy X-ray bremsstrahlung, and makes use of the principle of different absorption coefficient and scattering coefficient when the X-ray cuts through different materials to check the internal blemish or internal structure of the material.
The characteristics of high-energy electron beam irradiation are "cold sterilization" and "cold treatment" without changing the shape; good preservation effect. Irradiation treatment of food has low energy consumption and low environmental pollution.
Compared with traditional isotope radioactive sources, electron accelerators are safer and more environmentally friendly; high-energy and high-power electron irradiation accelerators are more suitable for industrialized mass radiation processing, and the radiation produced by electron accelerators has controllable, high-energy, non-nuclear waste, and no Harm to the environment, it is an ideal radiation source that meets the requirements of sustainable development.
The development and application of irradiation devices at home and abroad have proved that the use of high-energy and high-power electron accelerators as irradiation devices is an inevitable trend in the development of the radiation processing industry.
Comparison of electron accelerator and cobalt 60 radiation source
Compared with the 60Co radiation source, the industrial irradiation electron accelerator has a higher power, generally a few kW to a few hundred kW, and the dose rate produced is 3 to 4 orders of magnitude higher than that of the 60Co radiation source. The direction is concentrated, the energy utilization rate is high, and the production High efficiency, suitable for large-scale irradiation processing industry. However, the penetrating power of the electron beam is low, and its application also has certain limitations. Another important advantage of the industrial irradiation electron accelerator is that it is relatively safe and radiation protection is easier. There is radiation when the accelerator is turned on, and there is no primary radiation after the power is shut down, which greatly reduces the probability of radiation safety accidents. When the electron energy is lower than 10MeV, the irradiated material will not produce induced radioactivity, so it will not cause radioactive pollution. When the equipment is scrapped at the end of its life, only ordinary industrial waste is left. Unlike the 60Co radiation source, which still has a higher activity, the waste radioactive source needs to be decommissioned. The surrounding environment is relatively safe and there is no threat of radioactive pollution.
Accelerator scheme design
High-energy and high-power electron irradiation accelerator is a multi-disciplinary comprehensive industrial production equipment, which involves high-current long-life electron gun, microwave radio frequency, high-voltage pulse power supply, high vacuum, computer, control, machinery, magnetic field, electronics, radiation dosimetry, etc. For several professional technologies, problems in any part will affect the normal operation of the accelerator. Very high product requirements are put forward for the design, manufacturing and debugging of high-energy and high-power electron irradiation accelerators.
electron accelerator process
When the electron beam generated by the electron gun flows through the accelerating tube, the electron beam continuously obtains microwave energy in the accelerating tube and is accelerated to a high-energy, high-power electron beam output from the outlet of the accelerating tube, and then enters the scanning box, and uses the scanning magnetic field to flow the electron beam. Sweep to a certain width, lead out from the output window, and irradiate the moving object. The high-energy electron beam is irradiated on the heavy metal target to generate bremsstrahlung, and the high-energy X-ray converted into it is used to irradiate the irradiated item, and the penetration ability is greatly increased.
Accelerator energy classification
Low-energy accelerators (80keV~300keV) are mainly electron curtain accelerators. It is a high-pressure accelerator without accelerating tube and scanning device, small in size, regular in appearance, self-shielding function, and relatively simple in structure. This type of accelerator is mainly used in radiation treatment of thin-layer materials or surface coatings.
Medium-energy accelerator (0.3MeV~5MeV) The electron accelerator in this energy zone is mainly high-pressure accelerator, and its representative model is high-frequency and high-pressure accelerator, also known as Dinami accelerator. Its main industrial application areas are: radiation cross-linking of polyethylene insulation materials for wires and cables and polyethylene foamed plastics, rubber vulcanization, radiation production of high-strength temperature-resistant polyethylene thermoplastic pipes, and radiation cross-linking of electric heating cables, etc.
High-energy accelerator (5MeV~10MeV) The electron accelerator in this energy zone is mainly an electron linear accelerator. Electron beams with beam energy less than 7.5MeV can also be converted into X-rays for irradiation, but the X-rays converted by electron beams greater than 5MeV involve the safety of induced radioactivity. This energy zone accelerator has a wide range of applications, such as irradiation disinfection and sterilization of medical equipment and sanitary products, food irradiation preservation, grain pest control, import and export food inspection and quarantine, Chinese patent medicine sterilization, antibiotic degradation, environmental protection, semiconductors Device modification, new chemical product development, etc.
According to the form of accelerating electric field
(1) DC high-voltage accelerators: electron curtain accelerators, high-frequency high-voltage accelerators (Dinami), insulated-core transformer-type high-voltage accelerators, air-core transformer-type high-voltage accelerators, etc. are all accelerator types specially developed for industrial radiation processing.
(2) High-frequency accelerator: electron linear accelerator, ILU series single cavity resonant accelerator and Rhodotron resonant cavity accelerator.
Several common industrial irradiation electron accelerators
1) High-voltage doubler accelerator: product energy range 0.5~3.0MeV, power 50~100kW
2) Electron curtain accelerator: the energy range is generally (75~300) keV, and the power is generally (5~350) kW
3) High-frequency and high-pressure accelerator: Energy from (0.4~5.0) MeV, beam power can reach 300kW.
4) Insulated core transformer accelerator: the energy range is 0.3~3.0MeV, and the beam power can reach more than 100kW
5) Air-core transformer type accelerator: its energy range is 0.2~2.5MeV, electron beam current can reach 400mA, and maximum power can reach 400kW
6) Electron linear accelerator: the energy is generally controlled at 5~10MeV
7) Rhodotron accelerator
High-frequency and high-pressure accelerators can be divided into main structures: upright, horizontal and square type.
Design index of high-energy and high-power electron irradiation accelerator
Beam current (average) 1.5-2mA
Average beam power 15-20KW
Repetition frequency: 10-650Hz
Pulse width 14-16us
Beam stability: 3%
Beam dose stability: 5
Scanning width 1000mm
Able to operate continuously and stably for 24 hours
Accelerator supporting system
(1) Transmission chain height: 550mm
(2) Transmission chain width: 1000m
(3) Transmission chain speed: 1-15m/min
(4) The height of the transmission chain from the surface of the titanium window: 835mm
(5) Transmission chain length: 70000mm
Accelerator supporting system, transmission chain characteristics
(1) The scanning speed is adjustable 1-15m/min, corresponding to 30kGy-1kG
(2) The objects to be illuminated under the beam are concentrated and pulled apart before and after exposure, which is convenient for power utilization and transportation
(3) The transmission chain under the beam can be raised and lowered, and the lifting distance is 0-400mm
(4) There is a 180° turning mechanism at the entrance, which can realize 1/3 seconds
(5) Two moving mechanisms to ensure that the box is turned left and right after being turned over
(6) The guiding function aligns the illuminated object with the scanning width
(7) Height limit to ensure the safety of the illuminated objects
Safety of Irradiation Accelerator System
1. Personal safety
Warning bell before turning on
Warning light reminder when starting up
Telephone contact before starting
Emergency stop button in emergency
Overdose alarm for each person and system
Irradiation safety inspection before leaving east
Guarantee of the monitor system
Training before operation
Strict safety rules and regulations
2. Machine safety chain
High voltage overcurrent protection interlock
Water pressure, overpressure and underpressure interlock
Air pressure, overpressure air pressure interlock
Scanning the railway chain
Transmission chain linkage
Modulator door interlock
How much does a electron accelerator cost?
High-energy electron accelerator irradiation processing application investment and payback period.
The total investment is 3-5 million US dollars.
The payback period is 5.31 years before tax; 5.97 years after tax. The fund recovery period is short, and it has good economic, social and ecological benefits. The project has a broad prospect.