Why is Chernobyl deemed to not be habitable for 22,000 years despite reports and articles everywhere saying that the radiation exposure of being within the exclusion zone is less you’d get than flying in a plane or living in elevated areas like Colorado or Cornwall?
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I haven’t read all the way down the threads and, for that, I apologize if it has already been discussed. Also l, this is way beyond ELI5 but as is often the case, curious people that ain’t 5 want to go deeper. So here goes.
I’m someone that works with radioactive materials as part of my job. I don’t claim to have authoritative knowledge on the subject but I have more than the average Joe.
This isn’t a direct answer to OP’s inquiry but I want to share a couple of concepts in the field 1) Deterministic and 2) Stochastic.
1) Deterministic outcomes are those that are radiation dose dependent. For example, if a person gets a concentrated skin dose (meaning a exposed small area, say during a long medical procedure) of, say, some several hundred centi-Gray of radiation, they are *expected* to have skin reddening (erythema, in medical parlance). These are dose dependent outcomes. The higher the dose, the more terrible the outcome. There are known doses, that when that threshold is crossed, cause expected outcomes. These are deterministic effects of radiation.
One useful way that I think about deterministic and how dose dependence works is in this way (probably getting into some upper level biology weeds here):
Think of the cells in your body that reproduce the most often. Think skin cells, lining of your gut, sex cells. The more often a cell reproduces, the more often it’s genetic material is replicating; replication is a wee bit error prone to begin with so it makes sense that some outside insult would be able to mess with the process because it has more opportunity.
Knowing this, we can see (and it roughly bears out) that skin gets damaged at lower doses followed by x and y and z. Interestingly, neurons, which conventional knowledge says replicate very little, are the most radiation resistant; however there is a known gigantic dose that causes damage to them, even. Bad way to go, too.
2) Stochastic is risk. Every time you are exposed to ionizing radiation, your risk for a biological effect (bad, in practice) increases. This includes getting walking to your vehicle on a sunny day (lowest dose, in this discussion), flying from LA to NYC, routinely laying in peak sunshine for years in order to get a nice suntan or having 10 CT scans a year. These are the levels of radiation dose that do damage, but, in terms of cancer (which incidentally is the only life threatening long term stochastic effect I can think of off the top of my head) the more you’re exposed, to the *risk* you face of developing cancer increases.
Adding here as an aside: A lot of the information we have on biologic effects of radiation come from radiation disasters, inflicted by humans purposely, and accidentally.
In a way to drive it home:
Those resulting deterministic effects were studied in the short term.
Stochastic effects took long prospective studies to determine if the risk of bad outcomes was due to what was theorized.
TL:DR
Deterministic: The level of exposure equals the biological damage done. And it happens soon.
Stochastic: It’s not a guarantee but a risk of bad outcomes years down the road.
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