One question per week — let’s discuss the hazards of nuclear radiation pollution and the measures to prevent and control it

This post was last edited by yzhang2010 on 2011-8-8 at 16:38. The rays emitted by radioactive substances are like rows of bullets fired from a machine gun. The difference is that the rays “**” have an extremely small size and high speed; they can penetrate human cells, posing a great threat to the body. When the radiation level is low, the damage to human cells is minimal, and the body has enough time to repair those damaged cells ； However, when the level of radiation is very high, its destructive effect on human cells becomes significant. The body is then unable to repair all the damaged cells, leading to illness or even death. So how can we prevent nuclear radiation? 1. Research shows that the harm of nuclear radiation to the human body is related to the excessive oxidation it causes in the body. Therefore, to protect against nuclear radiation, in addition to avoiding close contact with radiation sources, proper nutrition plays a very important role in combating radiation. In nuclear bases, nuclear arsenals, nuclear submarines, and areas where nuclear explosions occur, people can use diet as a means to counteract or reduce the damage caused by nuclear radiation to the human body. For example, eating more black sesame seeds can reduce the harm caused by nuclear radiation to the human body. In addition, there are also amaranth, green tea, tomatoes, apricots, watermelons, red grapes and other fruits, as well as kelp, spirulina, pollen, ginkgo leaf products, etc., all of which can partially protect human tissues from the harm of nuclear radiation. In short, the basic principle for preventing and combating nuclear radiation is to ensure an adequate and comprehensive supply of energy to the body, with no lack of any nutritional elements. However, the intake of fats and proteins should not be too high; it is necessary to consume more vitamins to maintain a balanced level of minerals in the body. 2. One must be vigilant against radiation pollution that lurks around us. For example, pay attention to radioactive pollution in living quarters. With the development of industry, industrial waste residues are often used as building materials, which may result in the presence of certain radioactive substances in these materials. Furthermore, granite and other slabs used for decorating rooms also contain a certain amount of radioactive substances. Therefore, frequently opening the windows in living rooms to promote air circulation is an effective measure for reducing the concentration of radioactive substances indoors. 　　3. Be cautious of nuclear radiation contamination of drinking water. Water contaminated with radioactive substances cannot be drunk directly. Agricultural products grown using water contaminated with radioactive substances cannot be eaten either. China is rich in mineral water resources, and many of these sources are contaminated by artificial or natural radiation along their flow path; drinking such mineral water for a long time can be harmful to the health. 　　4. Do not wear gold and silver jewelry for long periods of time. Wearing jewelry frequently can also cause problems, namely the risk of developing \"jewelry diseases,\" which are skin conditions. Generally speaking, apart from pure gold (24K) jewelry, other types of jewelry contain small amounts of materials such as copper, chromium, and nickel in their composition during manufacturing. This is especially true for those inexpensive, artificially made jewelry pieces with an extremely bright appearance; their material composition is even more complex, and there is also a risk of trace amounts of radiation. Tests have shown that nearly 10% of jewelry contains radioactive substances, and wearing it for a long time may induce skin diseases. Jewelry worn regularly should preferably be tested for radioactive substances.

This post was last edited by yzhang2010 on 2011-8-8 at 16:38. The hazards of nuclear radiation: In the event of a nuclear leak, the impact on people is manifested through nuclear radiation, also known as radioactive materials. These radioactive materials can enter the body through breathing, skin wounds, and the digestive tract, causing internal radiation. External radiation can travel a certain distance before being absorbed by the body, resulting in external exposure injuries to people. 　　The symptoms of radiation sickness caused by internal and external exposure include fatigue, dizziness, insomnia, skin redness, ulcers, bleeding, hair loss, leukemia, vomiting, diarrhea, etc. It can sometimes also increase the incidence of cancer, deformities, and genetic disorders, affecting the health of several generations. Generally speaking, the more radiation energy the body absorbs, the more severe the symptoms of radiation sickness become, and the greater the risks of cancer and birth defects. Protection against nuclear radiation: Targeted protective measures are taken based on the mode of action and characteristics of the hazards posed by nuclear radiation. 1 Protection methods against external irradiation: Exposure of the human body to external radiation sources is referred to as external irradiation. The principle of external radiation protection is to minimize the dose of radiation received by the human body, keeping it below the dose equivalent limits. Once the radiation source is identified, the factors that determine the dose of radiation received by the human body are the distance from the source, the exposure time, and the shielding in place. Therefore, protection against external radiation is generally addressed using three methods: \"distance,\" \"shielding,\" and \"time.\" 1.1 Increasing the distance from the radiation source: For a nuclear radiation “point” source, the radiation intensity is inversely proportional to the square of the distance. Therefore, increasing the distance between the human body and the radiation source is a simple and effective way to reduce the dose of radiation received by the body. 1.2 Reducing the duration of radiation exposure shortens the working cycle. The dose received by the human body equals the dose rate multiplied by time; therefore, in the same nuclear radiation field, the longer the exposure time, the greater the dose received. For radiation protection, in all environments where nuclear radiation is present. It should all be based on the principle of minimizing the exposure time. 1.3 Shielding: When nuclear radiation passes through a layer of material, it is absorbed due to ionizing collisions or other interaction processes, resulting in a reduction in the intensity of the radiation. Therefore. Depending on the nature of the radiation source, a suitable and thick layer of shielding material is placed around it, creating a barrier between the radiation source and the rescuers in order to \"block\" or \"reduce\" the exposure of human bodies to nuclear radiation particles. 2. Protection methods against internal irradiation: The irradiation of the human body by radioactive nuclides that have entered the body is referred to as internal irradiation. Internal exposure hazards arise from the direct inhalation of radioactive substances, as well as from their entry into the body through the mouth and throat, or via the skin and wounds. Therefore, internal irradiation can be reduced by decreasing the number of radiation sources, as well as the radiation level in the atmosphere, on the human body, or on object surfaces ； Wear protective clothing to prevent direct skin contact with the radiation source ； Wear a positive-pressure breathing mask or gas suit to prevent inhalation of radioactive dust ； Eating, drinking, and smoking are prohibited in controlled areas, and the pathways through which radioactive substances can be ingested are restricted ； Take precautions such as avoiding entering radiation-controlled areas with exposed wounds. 3. Main measures for protecting against nuclear power plant accidents 3.1 Patient management: First, estimate the dose of radiation exposure, taking into account information provided by biological, chemical, physical methods as well as clinical symptoms; distinguish between internal and external exposure, as well as whole-body and localized exposure, in order to determine the severity of the damage and to enable early diagnosis and treatment. 3.2 Organizational radiation monitoring: This includes monitoring of personnel, the environment, water sources, and food, with pollution levels determined to facilitate pollution control and protection measures. 3.3 Food processing: Based on the results of radioactive contamination testing of the food, it can be made edible by removing its packaging, peeling it, and rinsing it until it meets the allowable standards. 3.4 Potable water: The coagulation-precipitation filtration method is used to meet drinking water standards. 3.5 Clothing and equipment: Depending on the level of surface contamination, they are tapped, cleaned, and rinsed to meet the decontamination standards. 3.6 Environmental pollution: Control of access, isolation or relocation are employed; once the decay or dispersion has diluted to acceptable levels, normal operations can resume. Walls, floors, roads: Depending on the situation, the surface layer can be removed using a scraper or washed to meet the required standards. 3.7 Personal Protection: Maintain good personal hygiene and respiratory protection; depending on the circumstances, use protective masks and various types of face coverings, as well as protective clothing. After leaving contaminated areas, take a shower and change clothes, and monitor individual exposure levels closely. 3.8 Medical protection: Iodine tablets or other preventive medications should be taken as required by the situation. Long-term medical surveillance is conducted on populations with different exposure doses. 3.9 Public awareness and education: Utilize films, online videos and images, as well as produce promotional videos on nuclear accident emergency response.

This post was last edited by yzhang2010 on 2011-8-8 at 16:39. Reply to 1# fangqiong: Hazards of nuclear radiation: 1. If the absorbed dose is low, there may be no symptoms at all； 2. If the absorbed dose is relatively high, mild “acute radiation sickness” may occur, characterized by vomiting, temporary leukopenia, and slight damage to hematopoietic function ； 3. In more severe cases, it can cause serious damage to hematopoiesis and gastrointestinal tract injuries ； 4. If the absorbed dose is extremely high, it will further damage the central nervous system and lead to immediate death ； 5. Six months after exposure to radiation contamination, physical changes may occur, including crystal opacities and cataracts; permanent infertility due to damage to the male testes and female ovaries; impaired bone marrow function leading to hematopoietic disorders; as well as the development of various cancers ； 6. It has genetic effects, causing mutations in the genes or chromosomes of reproductive cells, leading to problems such as birth defects. Preventive measures: 1. In the early stages of radiation contamination, if the skin or clothing becomes contaminated with radioactive substances, they must be thoroughly washed, and iodine tablets should be taken to prevent the body from absorbing these substances ； 2. If inhalation of radioactive substances has been confirmed and symptoms have appeared, only supportive treatment for the relevant symptoms can be provided, along with long-term monitoring for potential issues such as cancer in the future.

This post was last edited by yzhang2010 on 2011-8-8 at 16:40. Hazard: When the radiation level is low, the damage to human cells is minimal, and the body has enough time to repair those damaged cells； However, when the level of radiation is very high, its destructive effect on human cells becomes significant. The body is then unable to repair all the damaged cells, leading to illness or even death. The degree of harm caused by nuclear radiation to the human body is commonly expressed in numbers and units. The unit of absorbed dose can be expressed in gray (Gy); 1 gray is defined as the amount of energy, measured in joules, absorbed by 1 kilogram of material exposed to radiation. However, the dose received by the human body is generally calculated in terms of absorbed dose equivalent in sieverts (Sv). Absorbed dose equivalent is used to measure the degree of damage caused by radiation to human tissues. This involves weight factors. One sievert is equal to one gray multiplied by the weight factor of biological tissue. For example, the weight factor for the reproductive glands in the human body is 0.2; for the thighs, it’s 0.01; and for the entire body, it’s 0.05. Generally, an exposure dose to the human body exceeding 1 gray can cause acute radiation sickness or localized acute damage ； At doses below 1 Gy, mild symptoms such as dizziness, fatigue, and loss of appetite may occur ； At doses of 10–50 Gy, severe internal organ damage can occur, and death may occur within two weeks if no treatment is given ； A dose of 50 gray or more can be fatal within 2 days. When the entire human body is exposed to chronic radiation at doses exceeding safe levels over an extended period, chronic radiation sickness can occur, such as chronic skin damage, hematopoietic disorders, cataracts, and others. Chronic damage is common among occupational groups working with nuclear radiation. Embryos and fetuses are relatively sensitive to radiation; exposure to nuclear radiation during the fetal organ formation period can increase the rate of fetal malformations, as well as the neonatal mortality rate. The carcinogenic effect of nuclear radiation has been confirmed by animal experiments and epidemiological studies. In populations exposed to acute and chronic radiation, white blood cell counts drop significantly, and the incidence of various cancers such as lung cancer, thyroid cancer, breast cancer, and bone cancer increases with the dose of radiation. Furthermore, exposure to nuclear radiation can also cause genetic effects, leading to mutations in the genes or chromosomes of reproductive cells, with consequences that are difficult to predict. Prevention and control measures: 1. Studies have shown that the harm caused by nuclear radiation to the human body is related to the excessive oxidation it induces in the body. Therefore, to protect against nuclear radiation, in addition to avoiding close contact with radiation sources, proper nutrition plays a very important role in combating radiation. In nuclear bases, nuclear arsenals, nuclear submarines, and areas where nuclear explosions occur, people can use diet as a means to counteract or reduce the damage caused by nuclear radiation to the human body. For example, eating more black sesame seeds can reduce the harm caused by nuclear radiation to the human body. In addition, there are also amaranth, green tea, tomatoes, apricots, watermelons, red grapes and other fruits, as well as kelp, spirulina, pollen, ginkgo leaf products, etc., all of which can partially protect human tissues from the harm of nuclear radiation. In short, the basic principle for preventing and combating nuclear radiation is to ensure an adequate and comprehensive supply of energy to the body, with no lack of any nutritional elements. However, the intake of lipids and proteins should not be too high; it is necessary to consume more vitamins to maintain a balanced level of minerals in the body. 2. One must be vigilant against radiation pollution that lurks around us. For example, pay attention to radioactive pollution in living quarters. With the development of industry, industrial waste residues are often used as building materials, which may result in the presence of certain radioactive substances in these materials. Furthermore, granite and other slabs used for decorating rooms also contain a certain amount of radioactive substances. Therefore, frequently opening the windows in living rooms to promote air circulation is an effective measure for reducing the concentration of radioactive substances indoors. 　　3. Be cautious of nuclear radiation contamination of drinking water. Water contaminated with radioactive substances cannot be drunk directly. Agricultural products grown using water contaminated with radioactive substances cannot be eaten either. China is rich in mineral water resources, and many of these sources are contaminated by artificial or natural radiation along their flow path; drinking such mineral water for a long time can be harmful to the health. 　　4. Do not wear gold and silver jewelry for long periods of time. Wearing jewelry frequently can also cause problems, namely the risk of developing \"jewelry diseases,\" which are skin conditions. Generally speaking, apart from pure gold (24K) jewelry, other types of jewelry contain small amounts of materials such as copper, chromium, and nickel in their composition during manufacturing. This is especially true for those inexpensive, artificially made jewelry pieces with an extremely bright appearance; their material composition is even more complex, and there is also a risk of trace amounts of radiation. Tests have shown that nearly 10% of jewelry contains radioactive substances, and wearing it for a long time may induce skin diseases. Jewelry worn regularly should preferably be tested for radioactive substances.

There’s no way to block radiation, unless one wears radiation-proof clothing; but such clothing is very expensive. Back when we were in the school laboratory, we were given that kind of clothing to wear when entering radiation-exposed areas, and we had to sign a document confirming our identity… In everyday life, there’s no good solution.

This post was last edited and replied to by yzhang2010 on 2011-8-8 at 16:40. Reply 1# fangqiong: The main hazards of nuclear and radiation ** incidents stem from the dispersion of radioactive materials in the environment; this leads to radioactive contamination of the environment (atmosphere, water, soil, ecosystems), thereby exposing the public to radiation. This exposure can be direct external exposure to radioactive materials (including exposure from radioactive substances in the air, soil deposits, as well as those on the skin and clothing), or it can be internal exposure resulting from inhaling contaminated air or consuming contaminated water and food. No acute effects occur at very low radiation doses. As the exposure dose increases and the number of exposed individuals rises, the incidence of cancer will also increase. Only at higher doses may certain acute toxic effects occur; at very high doses, it can lead to acute radiation sickness or even death. Another harm caused by nuclear and radiation **incidents is the significant economic losses, not only during the response to such incidents but also in the processes of environmental cleanup and restoration that follow. Another major hazard that requires special attention in nuclear and radiation **incidents is the severe psychosocial impact on the public. Due to the public’s extreme sensitivity to radiation, the psychological effects it causes are often much more severe than the harm radiation can inflict on the human body. In the event of a nuclear and radiation emergency, especially when large amounts of radioactive material are released into the atmosphere, a series of protective measures should be taken to safeguard the public, emergency responders, and those involved in cleanup efforts: ① Conduct radiation monitoring of the area affected by the emergency and its surrounding environment in order to assess the potential radiation hazards to people ； ②Intervention levels, action levels, and emergency exposure levels are established; when these levels are reached or exceeded, corresponding intervention or protective measures should be taken to limit people’s exposure dose ； ③Take protective measures for personnel, including concealment, ingestion of stable iodine, evacuation, personal protection, control of entry and exit routes, temporary relocation, permanent resettlement, elimination of radioactive contamination, and intervention in food use ； ④Provide the injured with the necessary medical care, and arrange for them to receive treatment at different levels of medical facilities depending on the severity of their injuries ； ⑤Other emergency rescue measures may be adopted as appropriate, such as fire fighting, communication and liaison, alarm reporting, security, transportation, and setting up temporary shelters.

This post was last edited by yzhang2010 on 2011-8-8 at 16:41. The rays emitted by nuclear radiation are like rows of bullets fired from a machine gun. The difference is that the rays “**” have an extremely small size and high speed; they can penetrate human cells, posing a great threat to the body. When the radiation level is low, the damage to human cells is minimal, and the body has enough time to repair those damaged cells ； However, when the level of radiation is very high, its destructive effect on human cells becomes significant. The body is then unable to repair all the damaged cells, leading to illness or even death. When the entire human body is exposed to chronic radiation at doses exceeding safe levels over an extended period, chronic radiation sickness can occur, such as chronic skin damage, hematopoietic disorders, cataracts, and others. Chronic damage is common among occupational groups working with nuclear radiation. Embryos and fetuses are relatively sensitive to radiation; exposure to nuclear radiation during the fetal organ formation period can increase the rate of fetal malformations, as well as the neonatal mortality rate. The carcinogenic effect of nuclear radiation has been confirmed by animal experiments and epidemiological studies. In populations exposed to acute and chronic radiation, white blood cell counts drop significantly, and the incidence of various cancers such as lung cancer, thyroid cancer, breast cancer, and bone cancer increases with the dose of radiation. Furthermore, exposure to nuclear radiation can also cause genetic effects, leading to mutations in the genes or chromosomes of reproductive cells, with consequences that are difficult to predict. Therefore, to protect against nuclear radiation, in addition to avoiding close contact with radiation sources, proper nutrition plays a very important role in combating radiation. Be vigilant against radiation pollution lurking around us, such as paying attention to radioactive contamination in living spaces. Be cautious of nuclear radiation contamination of drinking water. Water contaminated with radioactive substances must not be consumed directly, nor should agricultural products grown using such water be eaten. Do not wear gold and silver jewelry for long periods. For jewelry that is worn frequently, it’s best to have it tested for radioactive substances.

This post was last edited by yzhang2010 on August 8, 2011, at 16:41. The main hazards stem from the dispersion of radioactive substances in the environment; this leads to radioactive contamination of the environment (atmosphere, water, land, and ecosystems), resulting in radiation exposure for the general public. This exposure can be direct external exposure to radioactive materials (including exposure from radioactive substances in the air, soil deposits, as well as those on the skin and clothing), or it can be internal exposure resulting from inhaling contaminated air or consuming contaminated water and food. No acute effects occur at very low radiation doses. As the exposure dose increases and the number of exposed individuals rises, the incidence of cancer will also increase. Only at higher doses may certain acute toxic effects occur; at very high doses, it can lead to acute radiation sickness or even death. In the event of a nuclear and radiation emergency, especially when large amounts of radioactive material are released into the atmosphere, a series of protective measures should be taken to safeguard the public, emergency responders, and those involved in cleanup efforts: ① Conduct radiation monitoring of the area affected by the emergency and its surrounding environment in order to assess the potential radiation hazards to people ； ②Intervention levels, action levels, and emergency exposure levels are established; when these levels are reached or exceeded, corresponding intervention or protective measures should be taken to limit people’s exposure dose ； ③Take protective measures for personnel, including concealment, ingestion of stable iodine, evacuation, personal protection, control of entry and exit routes, temporary relocation, permanent resettlement, elimination of radioactive contamination, and intervention in food use ； ④Provide the injured with the necessary medical care, and arrange for them to receive treatment at different levels of medical facilities depending on the severity of their injuries ； ⑤Other emergency rescue measures may be adopted as appropriate, such as fire fighting, communication and liaison, alarm reporting, security, transportation, and setting up temporary shelters. How to protect against external radiation? The external exposure dose can be reduced through three approaches. First, stay away from radiation sources. When handling a discarded, unused, or unclaimed radioactive source, long-handled handling tools should be used whenever possible. When possible, use a robot to remotely control the handling of the radiation source. Unless necessary, personnel not on duty should stay away from radiation sources and not enter areas contaminated with radiation. Second, reduce the contact time with the radiation source. Therefore, training for personnel involved in the emergency response to nuclear and radiation incidents should be strengthened to improve their proficiency and reduce operation time. Third, effectively utilize shields to reduce the intensity of radiation acting on the human body. When dealing with a single radiation source, objects with good shielding properties (such as lead bricks, iron plates, concrete slabs) should also be used to reduce the dose of radiation received by the human body. The shielding capability of buildings and large vehicles and ships against penetrating radiation can also be utilized. Inside a house, the shielding performance is better in the inner areas than in the outer areas; it is better at the corners than in the center of the room, and even better behind doors. 24. How to protect against internal radiation? To prevent the inhalation of radioactive dust, it is first necessary to avoid re-contaminating the air near the ground with dust; therefore, actions such as walking, vehicle traffic, or earthwork operations should all be carried out with care to minimize dust generation. When avoidance is truly impossible, methods such as increasing the distance between vehicles and changing the route can be used to stay away from dusty areas; moistening the ground appropriately can also help reduce dust suspension. For radioactive dust, masks generally provide satisfactory protection, with an efficiency in blocking such dust ranging from 80% to 90%. However, the masks must be worn correctly to prevent leakage on the sides. What were the early protective measures? After a nuclear and radiation emergency occurs, especially in the early stages (within 1–2 days) following the release of large amounts of radioactive material into the atmosphere, protective measures that can be taken for people include hiding, respiratory protection, taking stable iodine, evacuating, and controlling access routes. Measures such as concealment, evacuation, and control of entry and exit routes are effective in protecting against external exposure caused by radioactive nuclei in the plume, internal contamination resulting from those radioactive nuclei, as well as external exposure due to surface radioactive contaminants. What are the medium-term protective measures? In the middle stage of the event, a large amount of radioactive material has already settled on the ground, and sometimes it may continue to be released into the atmosphere. At this point, for individuals, other early preventive measures can continue to be taken, in addition to considering the removal of respiratory protection. To avoid excessive cumulative doses resulting from prolonged exposure, the authorities can take controlled and planned measures to relocate the population away from the polluted areas – namely, evacuation. Consideration should also be given to restricting the sale and consumption of food and drinking water produced or stored locally. Based on the characteristics of exposure routes for personnel during this period, additional protective measures that can be taken include using stored feed in the livestock industry, cleaning the human body surface, and providing treatment for the injured and sick. What are the protective measures in the late stage? The problem in making decisions regarding protective measures in the later stage of an accident (the recovery phase) is determining whether and when normal social life can resume in areas where protective measures were already taken in the early and middle stages, or whether further protective measures are needed. In the later stages of the event, the main route of exposure was internal radiation caused by ingesting contaminated food and inhaling resuspended particles. Therefore, the protective measures that can be taken include controlling entry and exit routes, relocating people, controlling food and water, and using stored feed as well as carrying out decontamination of the area. What should the public do in the event of a nuclear or radiation emergency? In the event of a nuclear or radiation emergency, the first thing the public must do is to obtain as much reliable information as possible about the emergency, and to be aware of **the decisions and announcements made by the relevant authorities. To this end, it is necessary to maintain communication with local **through various means (television, radio, telephone, etc.), and one must never trust rumors or unverified information. The second thing is to promptly take the necessary self-protection measures in accordance with local **notifications. For example: ① Use the nearest building for sheltering to reduce direct external exposure and inhalation of polluted air. Close the doors, windows, and ventilation equipment (including air conditioners and fans), and quickly open them again once the polluted air has passed. ②In accordance with the local arrangements, evacuate the area in an organized and orderly manner to avoid any serious negative consequences that might arise from the evacuation. ③When it is determined that a radioactive release has occurred, one should try to take cover to the side away from the wind direction and quickly enter a building to hide. ④Cover your mouth and nose with a wet towel, cloth, etc. to protect your respiratory tract. ⑤If radioactive contamination on the body surface is suspected, bathing and changing clothes can be used to reduce radiation-induced contamination. ⑥Follow the arrangements of the local authorities to determine whether it is necessary to control the use of local food and water. In the event of a nuclear and radiation **incident**, the public should pay special attention to maintaining a calm mindset and must not become panicked. How should the initial responders who arrive at the scene first protect themselves? In the event of a nuclear and radiation emergency, in the early stages, the first responders to arrive at the site are the emergency rescue personnel. In most cases, they should be radiation monitors, firefighters, police officers, medical staff, etc. To minimize the risk of exposure for these individuals, it is first necessary to make them aware of the three principles for reducing radiation dose, namely: ① Minimize the time spent in an environment with abnormal radiation ； ②The distance from the radiation source should be large ； ③If possible, make full use of screen shielding. For the first time, they need to be equipped with radiation detectors and personal dosimeters that can emit alarms, as well as necessary personal protective equipment such as protective masks or respirators, protective clothing, protective boots, and hats.

This post was last edited by yzhang2010 on 2011-8-8 at 16:42. 1. When a certain amount of radioactive material enters the human body, it not only possesses biochemical toxicity but can also cause damage to the body through its radiation effects; this effect is known as internal radiation； Exposure of the human body to ionizing radiation outside the body can also cause damage; this effect is known as external irradiation. Radiation damage is a term that refers to the various biological effects caused by various types of ionizing radiation acting on the human body. This is due to the ionization and excitation caused by various types of ionizing radiation (such as X or gamma rays, beta rays, alpha rays, and neutron beams), which transfer energy to the body and result in pathological changes in various tissues and organs. Radioactive nuclides can emit strong radiation in their surroundings, causing nuclear contamination. Radioactive fallout can also enter the human body through the food chain, and when it reaches a certain level in the body, it can have harmful effects. People may experience symptoms such as dizziness, headaches, and loss of appetite; as the condition progresses, symptoms like a decrease in white blood cells and platelets may occur. If excessive amounts of radioactive material affect the human body over a long period of time, it can cause tumors, leukemia, and genetic disorders. The hazards resulting from the leakage of radioactive materials from nuclear power plants are primarily associated with internal radiation exposure. The significant difference between internal and external radiation is that, even if handling of the radioactive material ceases, the radionuclides that have already entered the body continue to cause harmful effects within it. The cause of internal radiation exposure is usually inhalation of air contaminated with radioactive substances, consumption of water contaminated with radioactive substances, ingestion of food contaminated with radioactive substances, or the entry of radioactive substances into the body through the skin or wounds. Due to the different types of nuclides and their varying levels of toxicity, the degree of danger they pose also differs. Therefore, based on the degree of harm caused by the ingestion of radionuclides and their maximum allowable concentrations in the air, they are classified into four groups: highly toxic, highly poisonous, toxic, and lowly toxic. When handling radionuclides with different toxicities, there are various requirements regarding the equipment used for handling them and the location of the buildings in which such operations take place. Radiation protection can be further divided into internal exposure protection and external exposure protection. The basic principle of internal radiation protection is to block as many pathways as possible through which radioactive substances can enter the human body. The main measures taken include preventing radioactive substances from entering the body via the respiratory tract. The basic protective measures are: ① Air purification, which involves using methods such as air filtration and dust removal to reduce the concentration of radioactive dust or aerosols in the air as much as possible ； ② Ventilation dilution: Use ventilation systems to continuously remove contaminated air and replace it with clean air ； ③ Operate in a sealed environment; keep radioactive materials that could become sources of contamination inside sealed glove boxes or other closed containers, thereby isolating them from the air in the workplace ； ④ To enhance personal protection, operators should wear masks made of high-efficiency filtering materials, medical rubber gloves, and work uniforms ； In areas with severe air pollution, operators must wear helmets or protective suits while working. To prevent radioactive substances from entering the body through the mouth, it is strictly prohibited for staff to touch food, clothing, or other household items with potentially contaminated hands. Prevent large amounts of radioactive materials from being discharged into rivers, lakes, or deep wells with poor geological conditions without proper treatment, thereby avoiding contamination of surface water or groundwater sources. Establish an internal radiation monitoring system to conduct regular monitoring of the air, water sources, and representative agricultural and livestock products in the working environment as well as the surrounding area, so as to identify problems promptly and improve protective measures.

This post was last edited by yzhang2010 on 2011-8-8 at 16:43. The degree of harm caused by nuclear radiation to the human body is commonly expressed in numbers and units. The unit of absorbed dose can be expressed in gray (Gy); 1 gray is defined as the amount of energy, measured in joules, absorbed by 1 kilogram of material exposed to radiation. However, the dose received by the human body is generally calculated in terms of absorbed dose equivalent in sieverts (Sv). Absorbed dose equivalent is used to measure the degree of damage caused by radiation to human tissues. This involves weight factors. One sievert is equal to one gray multiplied by the weight factor of biological tissue. For example, the weight factor for the reproductive glands in the human body is 0.2; for the thighs, it’s 0.01; and for the entire body, it’s 0.05. Generally, an exposure dose to the human body exceeding 1 gray can cause acute radiation sickness or localized acute damage ； At doses below 1 Gy, mild symptoms such as dizziness, fatigue, and loss of appetite may occur ； At doses of 10–50 Gy, severe internal organ damage can occur, and death may occur within two weeks if no treatment is given ； A dose of 50 gray or more can be fatal within 2 days. When the entire human body is exposed to chronic radiation at doses exceeding safe levels over an extended period, chronic radiation sickness can occur, such as chronic skin damage, hematopoietic disorders, cataracts, and others. Chronic damage is common among occupational groups working with nuclear radiation. Embryos and fetuses are relatively sensitive to radiation; exposure to nuclear radiation during the fetal organ formation period can increase the rate of fetal malformations, as well as the neonatal mortality rate. The carcinogenic effect of nuclear radiation has been confirmed by animal experiments and epidemiological studies. In populations exposed to acute and chronic radiation, white blood cell counts drop significantly, and the incidence of various cancers such as lung cancer, thyroid cancer, breast cancer, and bone cancer increases with the dose of radiation. Furthermore, exposure to nuclear radiation can also cause genetic effects, leading to mutations in the genes or chromosomes of reproductive cells, with consequences that are difficult to predict. So how can we prevent nuclear radiation? 1. Research shows that the harm of nuclear radiation to the human body is related to the excessive oxidation it causes in the body. Therefore, to protect against nuclear radiation, in addition to avoiding close contact with radiation sources, proper nutrition plays a very important role in combating radiation. In nuclear bases, nuclear arsenals, nuclear submarines, and areas where nuclear explosions occur, people can use diet as a means to counteract or reduce the damage caused by nuclear radiation to the human body. For example, eating more black sesame seeds can reduce the harm caused by nuclear radiation to the human body. In addition, there are also amaranth, green tea, tomatoes, apricots, watermelons, red grapes and other fruits, as well as kelp, spirulina, pollen, ginkgo leaf products, etc., all of which can partially protect human tissues from the harm of nuclear radiation. In short, the basic principle for preventing and combating nuclear radiation is to ensure an adequate and comprehensive supply of energy to the body, with no lack of any nutritional elements. However, the intake of fats and proteins should not be too high; it is necessary to consume more vitamins to maintain a balanced level of minerals in the body. 2. One must be vigilant against radiation pollution that lurks around us. For example, pay attention to radioactive pollution in living quarters. With the development of industry, industrial waste residues are often used as building materials, which may result in the presence of certain radioactive substances in these materials. Furthermore, granite and other slabs used for decorating rooms also contain a certain amount of radioactive substances. Therefore, frequently opening the windows in living rooms to promote air circulation is an effective measure for reducing the concentration of radioactive substances indoors. 　　3. Be cautious of nuclear radiation contamination of drinking water. Water contaminated with radioactive substances cannot be drunk directly. Agricultural products grown using water contaminated with radioactive substances cannot be eaten either. China is rich in mineral water resources, and many of these sources are contaminated by artificial or natural radiation along their flow path; drinking such mineral water for a long time can be harmful to the health. 　　4. Do not wear gold and silver jewelry for long periods of time. Wearing jewelry frequently can also cause problems, namely the risk of developing \"jewelry diseases,\" which are skin conditions. Generally speaking, apart from pure gold (24K) jewelry, other types of jewelry contain small amounts of materials such as copper, chromium, and nickel in their composition during manufacturing. This is especially true for those inexpensive, artificially made jewelry pieces with an extremely bright appearance; their material composition is even more complex, and there is also a risk of trace amounts of radiation. Tests have shown that nearly 10% of jewelry contains radioactive substances, and wearing it for a long time may induce skin diseases. Jewelry worn regularly should preferably be tested for radioactive substances.