Doubling the distance between you and a source of radiation decreases your exposure by
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Although exposure to ionizing radiation carries a risk, it is impossible to completely avoid exposure. Radiation has always been present in the environment and in our bodies. We can, however, avoid undue exposure through the following protection principles: Show
Time, Distance, and ShieldingTime, distance, and shielding measures minimize your exposure to radiation in much the same way as they would to protect you against overexposure to the sun (as illustrated in the figure below):
ContainmentRadioactive materials are confined in the smallest possible space and kept out of the environment. Radioactive isotopes for medical use, for example, are dispensed in closed handling facilities, while nuclear reactors operate within closed systems with multiple barriers which keep the radioactive materials contained. Rooms have a reduced air pressure so that any leaks occur into the room and not out of it. NRC's System of Radiation ProtectionOver many decades, the U.S. Nuclear Regulatory Commission (NRC) has developed a system of radiation protection that reflects the world's improved understanding of the effects of radiation. In particular, the NRC ensures that users of radioactive materials keep radiation exposures within the agency's specified dose limits and as low as reasonably achievable. In addition, users must obtain a license from the NRC and be inspected to ensure that they are following the agency's regulations and safely using radioactive materials. The NRC's system includes regulations for the following aspects of radiation protection:
In addition, the NRC imposes penalties for failures to follow the agency's regulations. To keep radiation exposures as low as reasonably achievable, the NRC requires licensees to use radioactive materials in a way that limits the exposure of individual members of the public to a dose that does not exceed 0.1 rem (100 millirems) in a year. In addition, adults working with radioactive material must be protected so that they do notreceive more than 5 rems (5,000 millirems) per year. Because workers are exposed to various radiation sources, they are carefully monitored with the use of small instruments called dosimeters. If certain conditions are met, the NRC may enter into an agreement with a State governor to give the State authority for regulating radioactive materials. States that meet these conditions and agree to regulate materials using the same standards as the NRC are called Agreement States. Typically, Agreement States regulate all sources of radiation in the State except nuclear power plants, large quantities of certain nuclear material, and any high-level radioactive waste stored in the State. Currently, 35 states have such agreements with the NRC. Page Last Reviewed/Updated Friday, March 20, 2020 Time, distance and shieldingToo much radiation exposure can be harmful. The degree of radiation injury depends on the amount of energy absorbed, the type of radiation, and the time involved. In general, the higher the energy absorbed, the greater the severity of early effects (occurring within a few weeks) and the greater the possibility of late effects such as cancer. The amount of radiation dose a person receives can be limited through three principles: time, distance, and shielding. TimeDose rate is the rate at which the radiation is absorbed. Therefore, limiting the time of radiation exposure will reduce your radiation dose. DistanceLike light and heat, ionizing radiation spreads out as you get farther from the source. Increasing the distance between you and the radiation source you will reduce exposure by the square of the distance. Doubling the distance between your body and the radiation source will divide the radiation exposure by a factor of four. ShieldingLead or lead equivalent shielding for X-rays and gamma rays is an effective way to reduce radiation exposure. There are various types of shielding used in the reduction of radiation exposure including lead aprons, mobile lead shields, lead glasses, and lead barriers. How can you decrease your exposure to radiation?Time, Distance and Shielding
Distance: Just as the heat from a fire reduces as you move further away, the dose of radiation decreases dramatically as you increase your distance from the source. Shielding: Barriers of lead, concrete, or water provide protection from penetrating gamma rays.
What will happen if we increase the distance of the source of radiation?A greater distance from the radiation source can reduce radiation exposure. The amount of radiation exposure is not inversely proportional to the distance from the radiation source, but is inversely proportional to the square of the distance [2,4].
Why does radiation decrease with distance?The intensity of radiation decreases with distance from a source because the radiation diverges from the source and because the medium may absorb some of the radiation. The decrease due to divergence can be understood if one thinks of light radiating from a lamp.
Does distance reduce radiation?Maximize your distance from a radioactive source as much as you can. If you increase your distance, you decrease your dose.
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