3 ms·

low enough that humans could manipulate the stuff, behind several feet of steel, lead and concrete shielding, without immediately lethal radiation doses. Wait,

by gascan 9y ago

low enough that humans could manipulate the stuff, behind several feet of steel, lead and concrete shielding, without immediately lethal radiation doses. Wait, for real? I have zero training in handling fissile material, but I didn't think any significant level of radiation could make it through that much shielding.

mirimir 9y ago
As I said, people probably can't imagine :) OK, consider a tall gantry crane on wheels.[0] Now imagine a plate, several feet thick, with layers of steel, lead and concrete, suspended below the rails. With a cab on the top, and no line of sight through the holes for the cables. 0) https://houstonforkliftsafety.com/wp-content/uploads/2016/07/Gantry-Crane.jpg https://houstonforkliftsafety.com/wp-content/uploads/2016/07...
cocoablazing 9y ago
There are rooms in some of these facilities that have been known as infinity rooms because no readily available radiation meter would not saturate in them. The radiation field of a freshly removed power reactor fuel element is so strong that you couldn’t run past it fast enough to survive the dose.
- gascan 9y ago
  I fully understand direct exposure can be lethal nearly instantly. It looks like what I didn't understand is radiation-blocking of a material (lead, concrete, water) is actually a decay function (half of the radiation makes it through X feet) rather than an absolute function (no radiation makes it through X feet). In other words, given an infinitely radioactive source, you would require an infinitely thick lead barrier to protect you. Really, I should have guessed given everything else about radioactivity is the same way.
  - mirimir 9y ago
    Right, it's just like transparency for visible light. But many of the fission products in neutron-exposed uranium emit high-energy gammas. And even lead is somewhat transparent. Also, from what Google tells me, those "infinity rooms" at Hanford are probably contaminated with plutonium-239. That's an alpha emitter, and alphas (helium-4 nuclei) are pretty easy to stop.

by gascan 9y ago

mirimir 9y ago

As I said, people probably can't imagine :) OK, consider a tall gantry crane on wheels.[0] Now imagine a plate, several feet thick, with layers of steel, lead and concrete, suspended below the rails. With a cab on the top, and no line of sight through the holes for the cables. 0) https://houstonforkliftsafety.com/wp-content/uploads/2016/07/Gantry-Crane.jpg https://houstonforkliftsafety.com/wp-content/uploads/2016/07...

cocoablazing 9y ago

There are rooms in some of these facilities that have been known as infinity rooms because no readily available radiation meter would not saturate in them. The radiation field of a freshly removed power reactor fuel element is so strong that you couldn’t run past it fast enough to survive the dose.

gascan 9y ago
I fully understand direct exposure can be lethal nearly instantly. It looks like what I didn't understand is radiation-blocking of a material (lead, concrete, water) is actually a decay function (half of the radiation makes it through X feet) rather than an absolute function (no radiation makes it through X feet). In other words, given an infinitely radioactive source, you would require an infinitely thick lead barrier to protect you. Really, I should have guessed given everything else about radioactivity is the same way.
- mirimir 9y ago
  Right, it's just like transparency for visible light. But many of the fission products in neutron-exposed uranium emit high-energy gammas. And even lead is somewhat transparent. Also, from what Google tells me, those "infinity rooms" at Hanford are probably contaminated with plutonium-239. That's an alpha emitter, and alphas (helium-4 nuclei) are pretty easy to stop.