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Fundamental to radiation protection is the avoidance or reduction of dose using the simple protective measures of time, distance and shielding. The duration of exposure should be limited to that necessary, the distance from the source of radiation should be maximised, and the source or the target shielded wherever possible.
A satellite shielded by 3 mm of aluminium in an elliptic orbit (200 by 20,000 miles (320 by 32,190 km)) passing the radiation belts will receive about 2,500 rem (25 Sv) per year. (For comparison, a full-body dose of 5 Sv is deadly.) Almost all radiation will be received while passing the inner belt. [43]
There are three fundamental ways to reduce exposure to ionizing radiation: [32] increasing the distance from the radiation source; reducing the exposure time; shielding (i.e.: a physical barrier) Shielding is a plausible option, but due to current launch mass restrictions, it is prohibitively costly.
Distance: Radiation intensity decreases sharply with distance, according to an inverse-square law (in an absolute vacuum). [ 32 ] Shielding : Air or skin can be sufficient to substantially attenuate alpha radiation, while sheet metal or plastic is often sufficient to stop beta radiation.
Unprotected experiments in the U.S. in 1896 with an early X-ray tube (Crookes tube), when the dangers of radiation were largely unknown.[1]The history of radiation protection begins at the turn of the 19th and 20th centuries with the realization that ionizing radiation from natural and artificial sources can have harmful effects on living organisms.
Radiation dosimetry in the fields of health physics and radiation protection is the measurement, calculation and assessment of the ionizing radiation dose absorbed by an object, usually the human body. This applies both internally, due to ingested or inhaled radioactive substances, or externally due to irradiation by sources of radiation.
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