The SI unit of radiation dose is \"gray\" (Gy) which is radiation equivalent to
ID: 1770154 • Letter: T
Question
The SI unit of radiation dose is "gray" (Gy) which is radiation equivalent to 1 J/kg. A small energy delivered as ionizing radiation can create huge damage at the cellular level, and the sievert is a unit of the health effect of radiation proportional to the radiation dose, but multiplied by factors allowing for the absorption and and the nature of the radiation.
Which of these statements are true? You may need to research these answers, but they are useful to know.
NASA astronauts are allowed to receive a dose of 1 sievert during their career
A dose of 4 to 5 sieverts will kill a human with a 50% probability within 30 days if the dose is received over a short period (say accidental exposure).
The background radiation flying in a commercial aircraft is 10x the natural background at the surface of Earth.
The dosage from a dental X-ray is 1 milli-sievert.
The natural background radiation is about 1 milli-sievert a year
The background 50 km from the site after a nuclear weapons detonation is 1 sievert.
A.NASA astronauts are allowed to receive a dose of 1 sievert during their career
B.A dose of 4 to 5 sieverts will kill a human with a 50% probability within 30 days if the dose is received over a short period (say accidental exposure).
C.The background radiation flying in a commercial aircraft is 10x the natural background at the surface of Earth.
D.The dosage from a dental X-ray is 1 milli-sievert.
E.The natural background radiation is about 1 milli-sievert a year
F.The background 50 km from the site after a nuclear weapons detonation is 1 sievert.
Explanation / Answer
A) Partially true. Career exposure limits of NASA astronauts varies with gender and age. Female astronauts at the age of 25 are allowed to receive 1 Sv of radiation in their career. However for male astronauts if their career spans for a longer period of time, say till 55 years, their allowed dosage is 4 Sv(Sievert) during their whole career.
B)True. Typically 4-5 Sv received over a short period of hours will be lethal. So it is true that A dose of 4 to 5 sieverts will kill a human with a 50% probability within 30 days.
C)True. Natural background radiation at airline cruise altitude is 24 mSv per year. Human exposure to natural background radiation, (global average) is 2.4 m Sv/ year. So the background radiation flying in a commercial aircraft is
24/2.4=10
times. Which is roughly 10 times the natural background at the surface of Earth.
D) False. The dosage from a dental X-ray is 10 Sv = 0.01 m Sv(mili Sievert).
E) True. The natural background radiation on the earth's surface is about 1 to 3 milli sievert a year.
F) The background radiation after nuclear weapon detonation will depend on its yield and how much time has elapsed after the detonation. And initially, it is 1 Sv 50 km from the site after a nuclear weapons detonation
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