for anyone who is interested here's some info about different dirty bomb materials [hello, NSA]
...dirty bombs do not use fissile material. ... These materials...are
not radioactive enough.
Their radioactive emissions don't travel far and are blocked by simple barriers, including skin and clothing. A dirty bomb would use small amounts of highly radioactive materials such as cesium or cobalt, not uranium. Even specks of these elements send out deadly gamma rays that penetrate walls and bodies causing immediate injury. The Federation of American Scientists has
calculated that a mere
41 grams (1.4 ounces) of cesium-137 in a dirty bomb could contaminate most of Manhattan. By contrast,
it would take 1,460 tons [about 3 million pounds]
of low-enriched uranium to get the same levels of radiation.
Home > Programs > Strategic Security > Nuclear Information Project > Non-Proliferation and Arms Control
Uranium and Dirty Bombs
Even tiny amounts of a material with a half life of days will be intensely radioactive because the material is disintegrating so fast. It will not, however, be a good dirty bomb material because too much will decay while the bomb is being built. Even if the bomb disperses the material, just waiting several days for the material to decay naturally will allow people to return to the contaminated areas. At the opposite extreme, radioactive materials with extremely long half lives just do not decay quickly enough to cause much radiation. Looked at another way, to get dangerous levels of radiation requires huge quantities of material if the material decays very slowly. Uranium is more than 99% U-238, which has a half life of almost five billion years
Code:
[SIZE=2][U][B]Isotope[/B][/U][U][B]Primary Radiation[/B][/U][U][B]Weight of 1 Curie[/B][/U][U][B]Weight of 3500 Curies[/B][/U][/SIZE]
Americum-241 alpha 0.30 [B]grams[/B] 1.05 kilograms
Cobalt-60 gamma 0.91 [B][I]milli[/I]grams[/B] 3.20 [B]grams[/B]
Californium-252 alpha 1.88 [B][I]milli[/I]grams[/B] 6.59 [B]grams[/B]
Cesium-137 beta/gamma 11.8 [B][I]milli[/I]grams[/B] 41.40 [B]grams[/B]
Iridium-192 beta/gamma 0.11 [B][I]milli[/I]grams[/B] 0.39 [B]grams[/B]
Plutonium-239 alpha 16.8 [B]grams[/B] 58.70 kilograms
Plutonium-240 alpha 4.54 [B]grams[/B] 15.90 kilograms
Radium-226 alpha 1.04 [B]grams[/B] 3.64 kilograms
Strontium-90 beta 7.17 [B][I]milli[/I]grams[/B] 25.1 [B]grams[/B]
Uranium-238 alpha 3.06 [U]tons[/U] 10.7 thousand tons
Depleted Uranium (0.2%) alpha 2.10 [U]tons[/U] 7.35 thousand tons
Natural Uranium (0.70%) alpha 1.50 [U]tons[/U] 5.24 thousand tons
[B]Commercial Uranium (5%) [/B] [B]alpha 0.42 [U]tons[/U] 1.46 [U][I]thousand[/I][/U] tons[/B]
We're talking about 900 lbs of yellow cake per a single curie.
And if it's enriched to U 238 we're talking 6700 lbs of enriched uranium per single curie.
It doesn't seem that turning this yellow cake into a dirty bomb is going to be reasonably feasible. Certainly more could be done with the same resources.
