Who Sets Radiation Standards?
International Standards
Three international organizations recommend radiation protection levels: the International Commission on Radiological Protection (ICRP), the International Atomic Energy Agency (IAEA) and the International Commission on Radiation Units and Measurements (ICRU).
U.S. Standards
U.S. groups involved with recommending radiation standards include the National Council on Radiation Protection and Measurements (NCRP) and federal and state agencies.
NCRP ~ National Council on Radiation Protection and Measurements
EPA ~ United States Environmental Protection Agency
NRC ~ United States Nuclear Regulatory Commission
Sources of Data Used to Set Radiation Standards
Two series of reports provide much of the data used in setting radiation standards. The reports are produced by National Academy of Sciences (NAS) and United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR).
Referencing from the Sievert (Sv) definition :
History
The sievert has its origin in the röntgen equivalent man (rem) which was derived from CGS units. The International Commission on Radiation Units and Measurements (ICRU) promoted a switch to coherent SI units in the 1970s, and announced in 1976 that it planned to formulate a suitable unit for equivalent dose. The ICRP pre-empted the ICRU by introducing the sievert in 1977.
The sievert was adopted by the International Committee for Weights and Measures (CIPM) in 1980, five years after adopting the gray. The CIPM then issued an explanation in 1984, recommending when the sievert should be used as opposed to the gray. That explanation was updated in 2002 to bring it closer to the ICRP’s definition of equivalent dose, which had changed in 1990. Specifically, the ICRP had introduced equivalent dose, renamed the quality factor (Q) to radiation weighting factor (WR), and dropped another weighting factor ‘N’ in 1990. In 2002, the CIPM similarly dropped the weighting factor ‘N’ from their explanation but otherwise kept other old terminology and symbols. This explanation only appears in the appendix to the SI brochure and is not part of the definition of the sievert.
Dose examples
| 98 | nSv: | Banana equivalent dose, an illustrative unit of radiation dose representing the measure of radiation from a typical banana |
| 250 | nSv: | U.S. limit on effective dose from a single airport security screening |
| 5–10 | μSv: | One set of dental radiographs |
| 80 | μSv: | Average (one time) dose to people living within 10 mi (16 km) of the plant during the Three Mile Island accident |
| 400–600 | μSv: | Two-view mammogram, using weighting factors updated in 2007 |
| 1 | mSv: | U.S. 10 CFR § 20.1301(a)(1) dose limit for individual members of the public, total effective dose equivalent, per annum |
| 1.5–1.7 | mSv: | Annual dose for flight attendants |
| 2–7 | mSv: | Barium fluoroscopy, e.g. Barium meal, up to 2 minutes, 4–24 spot images |
| 10–30 | mSv: | Single full-body CT scan |
| 50 | mSv: | U.S. 10 C.F.R. § 20.1201(a)(1)(i) occupational dose limit, total effective dose equivalent, per annum |
| 68 | mSv: | Estimated maximum dose to evacuees who lived closest to the Fukushima I nuclear accidents |
| 80 | mSv: | 6-month stay on the International Space Station |
| 160 | mSv: | Chronic dose to lungs over one year smoking 1.5 packs of cigarettes per day, mostly due to inhalation of Polonium-210 and Lead-210 |
| 250 | mSv: | 6-month trip to Mars—radiation due to cosmic rays, which are very difficult to shield against |
| 400 | mSv: | Average accumulated exposure of residents over a period of 9–20 years, who suffered no ill effects, in apartments in Taiwan constructed with rebar containing Cobalt-60 |
| 500 | mSv: | The U.S. 10 C.F.R. § 20.1201(a)(2)(ii) occupational dose limit, shallow-dose equivalent to skin, per annum |
| 670 | mSv: | Highest dose received by a worker responding to the Fukushima emergency |
| 1 | Sv: | Maximum allowed radiation exposure for NASA astronauts over their career |
| 4–5 | Sv: | Dose required to kill a human with a 50% risk within 30 days (LD50/30), if the dose is received over a very short duration |
| 5 | Sv: | Calculated dose from the neutron and gamma ray flash, 1.2 km from ground zero of the Little Boy fission bomb, air burst at 600m. |
| 4.5–6 | Sv: | Fatal acute doses during Goiânia accident |
| 5.1 | Sv: | Fatal acute dose to Harry Daghlian in 1945 criticality accident |
| 10 to 17 | Sv: | Fatal acute doses during Tokaimura nuclear accident. Hisashi Ouchi who received 17 Sv was kept alive for 83 days after the accident. |
| 21 | Sv: | Fatal acute dose to Louis Slotin in 1946 criticality accident |
| 36 | Sv: | Fatal acute dose to Cecil Kelley in 1958, death occurred within 35 hours. |
| 54 | Sv: | Fatal acute dose to Boris Korchilov in 1961 after a reactor cooling system failed on the Soviet submarine K-19 which required work in the reactor with no shielding |
| 64 | Sv: | Nonfatal dose to Albert Stevens spread over ≈21 years, due to a 1945 plutonium injection experiment by doctors working on the secret Manhattan Project. |
https://en.wikipedia.org/wiki/Sievert
Dose rate examples
All conversions between hours and years have assumed continuous presence in a steady field, disregarding known fluctuations, intermittent exposure and radioactive decay. Converted values are shown in parentheses. “/a” is “per annum”, which means per year. “/h” means “per hour”.
| <1 | mSv/a | <100 | nSv/h | Steady dose rates below 100 nSv/h are difficult to measure. |
| 1 | mSv/a | (100 | nSv/h avg) | ICRP recommended maximum for external irradiation of the human body, excluding medical and occupational exposures. |
| 2.4 | mSv/a | (270 | nSv/h avg) | Human exposure to natural background radiation, global average |
| (8 | mSv/a) | 810 | nSv/h avg | Next to the Chernobyl New Safe Confinement (May 2019) |
| ~8 | mSv/a | (~900 | nSv/h avg) | Average natural background radiation in Finland |
| 24 | mSv/a | (2.7 | μSv/h avg) | Natural background radiation at airline cruise altitude |
| (46 | mSv/a) | 5.19 | μSv/h avg | Next to Chernobyl Nuclear Power Plant, before installing the New Sarcophagus in November 2016 |
| 130 | mSv/a | (15 | μSv/h avg) | Ambient field inside most radioactive house in Ramsar, Iran |
| (350 | mSv/a) | 39.8 | μSv/h avg | inside “The Claw” of Chernobyl |
| (800 | mSv/a) | 90 | μSv/h | Natural radiation on a monazite beach near Guarapari, Brazil. |
| (9 | Sv/a) | 1 | mSv/h | NRC definition of a high radiation area in a nuclear power plant, warranting a chain-link fence |
| 2–20 | mSv/h | Typical dose rate for activated reactor wall in possible future fusion reactors after 100 years. After approximately 300 years of decay the fusion waste would produce the same dose rate as exposure to coal ash, with the volume of fusion waste naturally being orders of magnitude less than from coal ash. Immediate predicted activation is 90 MGy/a. | ||
| (1.7 | kSv/a) | 190 | mSv/h | Highest reading from fallout of the Trinity bomb, 20 mi (32 km) away, 3 hours after detonation. |
| (2.3 | MSv/a) | 270 | Sv/h | Typical PWR spent fuel waste, after 10-year cooldown, no shielding and no distance. |
| (4.6–5.6 | MSv/a) | 530–650 | Sv/h | The radiation level inside the primary containment vessel of the second BWR-reactor of the Fukushima power station, in February 2017, six years after a suspected meltdown. In this environment, it takes between 22 and 34 seconds to accumulate a median lethal dose (LD50/30). |
Rem equivalence
An older unit for the dose equivalent is the rem, still often used in the United States. One sievert is equal to 100 rem:
| 100.0000 rem | = | 100,000.0 mrem | = | 1 Sv | = | 1.000000 Sv | = | 1000.000 mSv | = | 1,000,000 μSv |
| 1.0000 rem | = | 1000.0 mrem | = | 1 rem | = | 0.010000 Sv | = | 10.000 mSv | = | 10000 μSv |
| 0.1000 rem | = | 100.0 mrem | = | 1 mSv | = | 0.001000 Sv | = | 1.000 mSv | = | 1000 μSv |
| 0.0010 rem | = | 1.0 mrem | = | 1 mrem | = | 0.000010 Sv | = | 0.010 mSv | = | 10 μSv |
| 0.0001 rem | = | 0.1 mrem | = | 1 μSv | = | 0.000001 Sv | = | 0.001 mSv | = | 1 μSv |
As such, in order to be applicable Internationally, we had used the International Standards to display the Dose Rate in :
μSv/h
Read as “micro sievert per hour”