What are the radioactive substances?

What are the radioactive substances? Radon * Radon and radon Randon are natural products of radioactive material attenuation on the earth. They are slowly released from soil, rocks, cement and sand. They are colorless and tasteless, and their specific gravity is seven and a half times that of air. They are the only natural radioactive gases in nature. Decay into solid particles. * About 20% of indoor radon comes from building materials. 80% outdoor infiltration. The radiation damage caused by radon accounts for all radiation damage in life. The incubation period of lung cancer induced by radon is more than 15 years, and lung cancer is related to radon in the world. Radon is the second largest lung cancer factor after smoking, which is listed as one of the carcinogens of 19 by WHO. In the United States, 5000~20000 people suffer from lung cancer due to radon every year, accounting for 10~ 14% of the total lung cancer. * Radon mixed with secondhand smoke is extremely harmful to health. Under the same radon content, smokers are more likely to get lung cancer than non-smokers. Radon has a high affinity for human fat, which affects the nervous system and makes people feel depressed and sleepy. Besides upper respiratory diseases and lung cancer, workers exposed to radon also have chronic nephritis, which is related to the transformation of radon into nephrotoxic radioactive uranium. Increase the probability of spontaneous abortion and deformed children in pregnant women. The decay of uranium 238 * radon will decay into other radioactive metal particles: polonium, lead 2 10 and bismuth, which are called daughters of radon, and a series of daughter elements produced after radon decay. * The decay time from radioactive radon to stable lead is about 25 years. * Radon and its daughters can form radioactive gas gel in air at room temperature. * Easy to be intercepted by the respiratory system and stay in the body. One cell in every 400 cells in the lung will mutate within one year due to the penetration of alpha particles, which is easy to cause genetic damage and form cancer. ? * Natural stone has different radioactivity due to its origin, geological structure and generation age. * Radioactive substances produced by decay, such as the content of degradable substances is too large, that is, the "specific activity" of radioactive substances is too high, which is harmful to human body. * Igneous building materials (especially granite stones) contain radioactive elements, which are particularly easy to release radon. * Radioactive radon may exist in Beitou Hot Spring Area, Guanggangyan Building Materials Building and Jinmen Granite Terrain in Taiwan Province Province. * The building materials that release radon are brick sand, cement, stones, tiles and gypsum, and the typical radon in building materials is ~40Bq/kg. Radiation dose unit Radiation intensity (activity) of radioactive waste * Curie: (Ci) is the unit of radioactivity. It is defined as the radioactivity released by one gram of radium. In memory of Julius and his wife. 1ci = 3.7×1010dps (transmutation/second), which is the radioactivity released by one gram of radium. Because its value is too large, it has been replaced by Bq. * Baker: (Bq) international speCial activity unit, 1 Bq = 1 dps (metamorphosis/second), and replaced Curie (ci). 1975, ICRU, the International Committee of Radiation Units and Metrology, wrote to several journals, mentioning that ICRU's suggestion was adopted at the metrology conference: Baker is an international special activity unit. * becquerel (1852- 1908) discovered radioactivity in 1896, and won the 1903 Nobel Prize in physics together with Julius and his wife * * *: the first Nobel Prize for studying radioactive substances. Equivalent dose: it is the product of absorbed dose of human tissues and radiation factor, which has included the significance of radiation damage to tissues and organs * 1 Sievert Sewart = 100 rem. The annual dose of natural radiation received by each person in Taiwan Province Province is about 2 millisieverts, and the government stipulates that the annual dose limit for professionals is 50 millisieverts per year. Radiation dose absorbed by the substance: * 1 Gregorian ray (joule/kg) = 100 rad. Radon gas * Soil gas produced by soil and rocks seeps indoors (radon in soil gas ~37 kBq/m3), flows out from underground with wells and springs, or outdoor air seeps indoors (average atmospheric radon in the United States ~ 65,438+00 bq/m3). * If you live or work in poorly ventilated places such as the first floor, basement, tunnel and mine, radon will be higher than the ground atmosphere, especially in closed storerooms and storage cabinets. Indoor automobile exhaust. * USEPA suggests that the concentration of radon should be kept below 4 pCi/L to be safe, especially in the basement, and more attention should be paid to the problem of poor ventilation. ICRP is suggested to be revised to above 4 pCi/L, (figure 10. 16,10.17) * 4 PCI/L = 4 *10-12 gift unit/.