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No, you are just confused about the technical jargon being used. That text is written for people who have had this jargon hammered into them and is very confus
by hunterpayne 1y ago
No, you are just confused about the technical jargon being used. That text is written for people who have had this jargon hammered into them and is very confusing to people who haven't. This is why people are told to not try to do the calculations themselves.
"Dose absorbed" is a physical measure of ionizing radiation that is directed at something. That's measured in rems or sieverts (or Grays, notice the spelling). "Dose equivalent" is a medical measure of the risk caused by that "Dose absorbed". That's measured in Greys (with an E, not an A). Both those measures combine the count rates for the 4 different types of radiation into 1 amount. "Dose equivalent" goes farther and is meant to calculate medical risk to a living person. Even more confusing there is a Gray (dose absorbed) and a Grey (biological impact of a dose absorbed, or dose equivalent); they are different.
The part about beta and gamma radiation is about establishing a baseline for converting between the two units but should never be used for calculating "dose equivalent" in practice. Its how we determine the value of 1 Grey. It isn't a way to convert from "dose equivalent" to "dose absorbed".
I'm trying to simplify this stuff for an audience without the necessary background information. Doing that requires me cutting out a bunch of details. The NRC text on the other hand is technically precise but also is mentioning a lot of things that are true but confusing or only useful for calibrating instruments. They are also explaining one tiny part of this and you left out the parts where they talk about how to combine the different counts for each type of radiation into one measurement. That's something else I'm also trying to explain at the same time. So I'm covering more ground and trying to do so with simpler terms. That's going to mean you can cherry pick stuff but doing that will to give you the wrong impression.
Natural background radiation varies by location on earth by a factor of 300. That 4 mSv per year is for natural background radiation at the low end of the scale which happens at sea level in places without Uranium or Thorium deposits. However, there are places where people live (and have lived for 1000s of years) where the natural background radiation is 300x that amount or about 1.2Sv/year. There is no observed increase in cancer rates in those locations despite decades of study. I'm also assuming that the "normal person" will take a flight or two and potentially be near other sources of radiation without knowing it (like your smoke detector).
PS The 50 mSv/year number is absurdly low. Its one of the main complaints about how the NRC handles nuclear radiation. Its literally lower than the natural background radiation at sites in India and Brazil.
- simoncion 1y ago> Dose equivalent" is a medical measure of the risk caused by that "Dose absorbed". That's measured in Greys (with an E, not an A). Neither the NRC nor the EPA nor the NIH nor the NRC seems to know about the "Grey". Everyone in the US seems to know about the "Gray" (abbreviated as "Gy"), which is used to measure dose and doesn't factor in biological harm. What country uses the "Grey" unit? What's the abbreviation of the "Grey" unit? Would you point to credible sources for the answers to those two questions? > "Dose equivalent" goes farther and is meant to calculate medical risk to a living person. Yes. That's biological harm. Getting hit on the skin from outside your body with a large amount of alpha radiation is far less harmful than getting hit with the same amount of gamma radiation. AFAICT, "dose equivalent" is measured in Sv or rems. If you can demonstrate a credible source for the "Grey" unit, then I can dismiss this as a time-wasting misunderstanding, but I've yet to see any reference to a "Grey" unit of radiation exposure. > Its literally lower than the natural background radiation [at some places on earth]... Yep. ALARA is a scourge. And I -too- have read Admiral Whatshisface's open letter from the 1980's or 1990's or whenever about how the regulation of the civilian nuclear energy program is batshit nuts by way of being negligently overcautious.