So, where does nuclear radiation come from in our daily lives? In what areas does it contribute to human beings? Nuclear applications in daily life, will not cause harm to the human body? March 30, the reporter on the people concerned about a series of topics, interviewed the provincial environmental protection department of the nuclear and radiation association, deputy secretary general, professor-level senior engineer Wang Hongjun.
Natural background radiation is not harmful
First of all, please tell us what is nuclear radiation.
Wang Hongjun: The human body is exposed to a variety of rays every day, we live in the environment everywhere there is radiation from nature, radiation and people's daily life as a shadow. Overall, people are often exposed to radiation can be divided into two categories, namely, nuclear radiation (also known as ionizing radiation) and electromagnetic radiation.
There are two common types of nuclear radiation, one is from nature's natural background radiation, such as cosmic rays, the Earth itself exists in the natural radioactive substances, they are widely present in the atmosphere, rocks, underground fissure water, soil. This kind of radiation is the background value of our living environment, which is generally not harmful to human beings. In our daily lives, our annual effective dose due to natural background radiation in our province is about 0.92 millisieverts. The other is due to nuclear-related activities caused by radiation, including medical irradiation produced by ray diagnostic examination and radiation therapy, industry, agriculture, scientific research and other applications of nuclear technology, nuclear weapons test explosions and the use of nuclear power production, etc., this time, the Fukushima nuclear power plant nuclear leakage caused by nuclear radiation belongs to the latter.
Compared to nuclear radiation, electromagnetic radiation is closer to life, it refers to the energy in the form of electromagnetic waves emitted by the source of the phenomenon of space. A variety of microwave appliances, electronic equipment, high-frequency furnace, mobile communications equipment and other devices, in the working state, it will be around the existence of electromagnetic radiation. People are familiar with microwave ovens, cell phones, high-voltage transmission and transformation, computers and other electromagnetic radiation generated belongs to this category.
10 times a year CT is harmless
What is the radiation dose in our daily life?
Wang Hongjun: Radiation in life is everywhere. According to the relevant information reports, traveling 2000 kilometers by plane is about 0.01 mSv of radioactive irradiation; an X-ray examination to receive radiation 0.1 mSv and so on. These radiations in daily life are called natural background doses. According to the national Basic Standards for Protection against Ionizing Radiation and for Radiation Safety, "the average annual effective dose to which the public is exposed as a result of practice should not exceed 1 mSv; under special circumstances, if the average annual effective dose for five consecutive years does not exceed 1 mSv, the effective dose for a single year may be increased to 5 mSv. "According to the relevant information, from a medical point of view, no effect on the human body is caused by an irradiated dose of less than 100 millisieverts. 100 millisieverts is equivalent to 1 year cumulative irradiation of about 10 times CT.
Nuclear radiation is colorless and tasteless, invisible and intangible, but can be detected and measured by instruments, mainly including α, β, γ three kinds of rays: the first two types of rays penetration is small, as long as the radioactive material does not enter the body, it will not produce internal irradiation of the human body, the impact is not great; the third type of ray penetration is stronger, and can Penetrate the human body and buildings, for the protection of this type of ray as long as you take a larger distance from the source of contamination, shorten the time of contact with the source of contamination and shielding through a variety of shielding body shielding, you can reduce the damage of radiation on us. Short time trace radioactive exposure will not jeopardize human health, but exposure to excessive nuclear radiation is harmful to the human body. It should be recognized that the human body itself has the function of repairing radioactive damage, and the size of this repair ability is related to the differences in individual qualities and the degree of initial damage.
The natural background dose is lowest in Dalian
Why is the natural background dose not the same in different cities in the province?
Wang Hongjun: natural background radiation from the atmosphere, soil, rocks and other environments, where geographically similar zones cosmic rays are basically the same, due to the natural radioactive series in the Earth distribution of Clark's value is not the same, so the province around the γ dose rate of the difference between high and low, mainly due to the rocks and geological structure, like Dandong, Benxi and other mountainous areas around Liaodong, most of the granite, Alkaline rock, radiation dose rate background value is high, while the Dalian area is low, Shenyang area is in the middle value.
Nuclear radiation technology is being used in a wide range of fields, is that right?
Wang Hongjun: Yes, nuclear science and technology is an emerging cutting-edge science and technology, in industry, agriculture, scientific research, medicine, environmental protection and national defense and other fields play an irreplaceable role. There are three nuclear irradiation centers in our province, mainly used for seed improvement, food sterilization and preservation, industrial materials detection. Nuclear radiation irradiation of crop seeds, plants, can prompt them to produce a variety of mutations, and then select from the need for heritable good variations, cultivated into new varieties. After nuclear irradiation, food can be sterilized and preserved without the use of preservatives, which are mostly used for some exported foods, such as seafood, instant noodles and so on. Industrial oil exploration and logging, pipeline flaw detection, large boilers, automobile tire flaw detection, etc., all need the corresponding application of nuclear technology to complete.
Nuclear radiation in the medical application of more
Nuclear radiation in the medical application of many.
Wang Hongjun: With the rapid development of science and technology, the application of nuclear radiation in the medical field is even more beneficial to mankind. Hospitals in the radiology, nuclear medicine, radiotherapy, interventional medicine, are in the application of this technology. Like radiology examination mainly uses X-ray equipment, such as CT, CR, DR, ordinary X-ray machine for general medical diagnosis; nuclear medicine is the advanced diagnostic technology of medicine, using a certain dose of a certain short-lived nuclides injected into the body through a vein or ingested into the body, to diagnose diseases such as thyroid, liver, brain, lungs, spleen, kidneys, heart, pancreas, and so on; radiotherapy is mainly the use of sealed sources, linear gas pedals to produce the Gamma and X-rays to irradiate deep tumors to inhibit and destroy the growth of tumor cells; Interventional Department is to carry out minimally invasive angiography, nephrography and cardiac stenting and other surgical treatments under X-imaging.
How does the province manage the safety of radioisotopes and radiation devices in these nuclear technology applications?
Wang Hongjun: China's use of radioisotopes and radiation devices units, the implementation of the radiation safety license system. Holders of units in the completion of the radiation environmental impact assessment, by the management of the strict examination, before receiving the radiation safety license. Holding units using radioisotopes and radiation devices from start to finish have a unified number code, the province's Nuclear Safety Bureau to carry out special law enforcement inspections every year.
Nuclear energy is safe, clean and efficient
Why should China develop nuclear power technology?
Wang Hongjun: non-renewable fossil energy (oil, coal, natural gas) generation takes hundreds of millions of years, the large-scale exploitation and utilization of human beings so that it is increasingly depleted; uneven distribution of hydroelectric resources; geothermal, wind, wave, tidal, solar energy and other renewable energy has not yet been realized large-scale industrial applications. And nuclear power can provide a large amount of electricity, it is the new energy that can meet the increasing energy demand of mankind.
Nuclear power is a safe, clean and efficient energy source. The development of nuclear power, not only can reduce the extraction and application of energy; and nuclear power generation without thermal power emissions brought about by the greenhouse effect, acid rain, soot and other damage to the environment, but also conducive to easing the transport capacity due to the transport of coal and other traffic brought about by the tension of the contradiction. Under normal circumstances, a million kilowatts of nuclear power plant on the impact of the surrounding annual effective dose of only 0.048 millisieverts, the normal operation of the nuclear power plant will not make the environmental background dose increase, while not to the public additional dose.