Dear Dr. Zoomie – I was watching The Man in the High Castle and there was a bit about weapons-grade uranium posing a health risk to people around it. Is this true? //

The short version is that uranium – even highly enriched uranium – is simply not very radioactive. I can confirm this from personal measurements – I’ve made radiation dose rate measurements on depleted uranium, natural uranium, and enriched uranium and none of them are very radioactive. Here’s why: //

. It takes about 100 rem to cause radiation sickness, about 400 rem to give someone a 50% chance of death (without medical treatment), and nearly 1000 rem to be fatal. With a dose rate of 1 R/hr at a distance of 1 meter this part’s easy – it’ll take 25 hours of exposure to cause a change in blood cell counts, 400 hours to give a 50% risk of death, and 1000 hours to cause death. At a speed of 60 mph it takes about 50 hours to cross the US – not even enough time to develop radiation sickness. And that’s for a person sitting for that whole time at a distance of 1 meter from the uranium...