On Sun, Jun 29, 2014 at 8:20 PM, meekerdb <meeke...@verizon.net> wrote:
> a LFTR does make U233, and more that it needs to keep functioning by > about 8%. > That depends on how the LFTR is designed and operated, if done correctly the figure is close to zero, just enough U233 to keep it going but no more. > Operating as designed this is contaminated with U232 which makes it > unsuitable for a bomb. > Yes, a sub-critical 5 Kilogram mass of LFTR produced U233 would give off a massive 43 Sieverts of radiation per hour, so the bomb makers would have to work fast because such an exposure would kill them in 72 hours and make them too sick to work a lot sooner than that. And because it is not the U232 itself that gives off those intense Gamma rays but a decay product of U232 (Thallium 208) after 10 years the radiation from that 5 KG chunk would not be less but would actually be 3 times more intense. By contrast the same amount of Plutonium would only give off .000003 Sieverts of radiation per hour and even less with U235. > > But if the operators skim out Pa233, which is the precusor to U233, and > then let it beta decay to U233 it's not contaminated by U232 and is usable > for a bomb. > Doing that would not violate the laws of physics but it would be damn hard to do. First of all you'd have to stop the reactor otherwise the neutron flux would continually make trace (but still deadly) amounts of U232 from U233 and Pa233. Then you'd need to set up a chemical extraction plant inside the reactor to get the Protactinium; a chemical plant that could deal with 700 degree Centigrade molten salt that is going to remain hot for years. Even if you waited one hour after reactor shutdown to let the shortest lived and thus most dangerous fission products to decay, just one liter of the salt would produce 350 watts of heat and would kill anyone in minutes unless they were protected by many meters of concrete. There is no way a rogue reactor operator could do all this without anybody noticing. And a rogue state wouldn't do it because there are far far easier ways to make a bomb than by using U233 and a LFTR. > > It's harder to make bomb from U233 because it's critical mass is about > half again that of plutonium but it has been done. > It's been done but not often and not well. No nation has a pure U233 bomb in it's stockpile because the attempts to make one were not encouraging. In 1955 the USA set off a plutonium-U233 hybrid composite bomb, it was expected to produce 33 kilotons but only managed 22. As far as I know the only pure U233 bomb was set off by India in 1988 and was a complete flop, it produced a miniscule explosion of only 200 tons of TNT. A LFTR economy would decrease the chances of weapon proliferation not increase it. A LFTR needs fissionable material to get started, it could use U233 made in another reactor but a better idea would be to use Plutonium, there are already thousands of tons of that dangerous stuff on the planet and this would be a great way to get rid of it. Also the Thorium economy would reduce the need for U235 enrichment plants. And by the way, there is a close cousin to the LFTR called a WAMSR that doesn't use Thorium but is specifically designed to eat nuclear waste; 200 of them could supply the entire world's electrical needs for 72 years by burning up the 270,000 tons of spent fuel rods that old fashioned reactors have already made. John K Clark -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
