Liberal Forum

Elements will have their radiation levels drop by
10 half-lifes = 1/1000
20 half-lifes = 1/1,000,000
30 half-lifes = 1/1,000,000,000

See this for a list of half-lifes: https://en.wikipedia.org/wiki/List_of_r ... _half-life

The most important thing to take away from this is short-half life means LOTS OF RADIATION but for only a SHORT TIME. So immediately following a detonation is the most important time to get sheltered. The radiation levels will drop quickly for the more lethal substances. Elements with long half-lifes don't emit much radiation so they aren't so problematic. However, elements with half-lifes comparable to the human life span are a BIG problem. This is because you can't shelter in place for a life time. You have to surface at some point. For the really bad stuff you can shelter for a couple months and it is largely gone. The mild stuff will be around for 1 million years but not all that harmful. But the stuff comparable to the human life span is quite harmful and it will retain a mild level of lethality. Most notable are elements like

Strontium-90: 29 year HL
Cesium-137: 30 year HL
Uranium 232: 69 year HL
Plutonium-238: 88 year HL