1, the atomic energy industry emissions of waste
Atomic energy industry in the refining of nuclear fuel, refining and nuclear fuel components manufacturing, there will be radioactive waste and waste water, exhaust emissions. These radioactive "three wastes" have the potential to cause pollution, due to the operation of the atomic energy industry production process have taken appropriate safety measures. The discharge of "three wastes" is also strictly controlled, so the pollution of the environment is not very serious. However, when an accident occurs in an atomic energy plant, the pollution is quite serious. There are examples of foreign countries have been forced to close the entire plant due to the failure of the atomic energy plant.
2, nuclear weapons test fallout
In the atmosphere, ground or underground nuclear tests, the radioactive material discharged into the atmosphere and the atmospheric airborne dust combined, due to the effect of gravity or rain and snow scouring and settling on the surface of the earth, these substances are called radioactive fallout or radioactive dust. Radioactive fallout dispersal range is very large, often can be settled to the entire surface of the earth, and the settlement is very slow, generally need a few months or even a few years to fall to the atmospheric troposphere or the ground, the decay of hundreds of years or even tens of thousands of years. 1945 U.S. in Japan's Hiroshima and Nagasaki dropped the two atomic bombs, so that hundreds of thousands of deaths, and a large number of survivors suffered from radiation sickness.
3, medical radioactivity
Medical examination and diagnostic process, the patient's body are subjected to a certain dose of radioactive irradiation, for example, a lung x-ray fluoroscopy, about to receive (4-20) × 0.0001Sv dose (1sv is equivalent to the energy absorbed by each gram of material 0.001J), for a stomach fluoroscopy , receiving a dose of approximately 0.015-0.03Sv.
4, scientific research radioactivity
Scientific research work in a wide range of applications of radioactive substances, in addition to the use of atomic energy research units, metal smelting, automation, bioengineering, metrology and other research departments, almost all involved in radioactivity-related topics and experiments. In these research work are likely to cause radioactive contamination.
Two, the characteristics of radioactive contamination
1, the vast majority of radionuclide toxicity, according to the weight of the toxin itself, are higher than the general chemical poisons.
2, according to the effect of radioactive damage, may affect heredity to future generations of hidden danger.
3, the size of the radioactive dose can only be detected by the radiation detector, non-human sensory organs can know.
4, the ray of sub-lighting with penetrating, especially r-ray can penetrate a certain thickness of the barrier layer.
5, radionuclides have the ability to metamorphose.
6, radioactive activity can only be weakened by natural decay.
Three, the harm of radioactive contamination on the human body
1, direct damage
Radioactive substances directly make the body material atoms or molecules ionized, destroying the body of certain macromolecules such as deoxyribonucleic acid, ribonucleic acid, protein molecules and some important enzymes.
2, indirect damage
A variety of radiation will first be widely present in the body of water molecules ionization, generating highly active H+, OH- and molecular products, and then through their role with the organic components of the body to produce the same results with the direct damage.
3, long-term effects
Mainly including radiation cancer, leukemia, cataract, life expectancy shortening and other aspects of the damage and genetic effects. According to the relevant information, young women in the pre-pregnancy diagnostic exposure to their children after the occurrence of Downs syndrome nine times more likely. For example, some pregnant women who had been exposed to radiation from the atomic bombs in Hiroshima and Nagasaki had given birth to mentally retarded children. According to a study by medical authorities, the percentage of children born to pregnant women diagnosed with radiation who developed cancer and leukemia as children increased.
Radioactive substances that enter the human body continue to emit a variety of rays in the human body causing internal irradiation. When the effective dose received is small, the physiological damage is not obvious, mainly in the form of an increased risk of cancer. It should be noted that there is absolutely no need to worry about the very low level of radioactivity that naturally exists in food. In recent years some experts believe that small doses of irradiation are not only harmless but also have certain benefits for the human body, known as the excitation effect.
Four, radioactive contamination prevention and control
1, the nuclear enterprise site selection in the surrounding low population density, meteorological and hydrological conditions conducive to the dilution of wastewater and waste diffusion, as well as seismic intensity of the region is relatively low to ensure that in the normal operation and the emergence of accidents, the irradiation dose suffered by the residents of the lower.
2, the choice of industrial processes and equipment selection to consider the amount of waste generated and safe and reliable operation.
3. Wastewater and waste are purified and treated, and the concentration and amount of radionuclide emissions are strictly controlled. Concentrated radioactive wastewater is generally solidified. alpha nuclide-contaminated waste and radioactive intensity of the waste for final disposal and permanent storage.
4. Monitoring is carried out around nuclear enterprises and in areas that may be subject to radioactive contamination.