What exactly are you asking? The material as a whole would have a shorter half life, and would require more mass for criticality. Any “fizzle” would be less intense than with an equal mass of 239. Is that what you mean?
Pu 240 is often touted as making plutonium unsuitable for weapons use. This is because its high spontaneous fission rate makes it even more prone to predetonation, even with implosion devices. That’s not to say that an implosion device with a Pu 240-contaminated pit won’t go boom, but it’ll tend to blow itself apart before it really gets going.
For this reason, chucking Pu 240-contaminated pits into a bucket would have similar effects to the non-contaminated pits. Assembly is too slow compared to the rate of spontaneous fission in either case.
This surprises me, although I’ll take your word for it. Most sources indicate a critical bare sphere of Pu 239 is about 10kg, with actual pits being 3-5 kg and possibly as small as 1 kg. Because of the geometry, two or even three, 5kg pits in a bucket may be subcritical.
Even fully assembled warheads in containers were storage problems. A 22" x 60’ earth covered magazine (igloo) might be limited to as few as 9 warheads in a specific spatial configuration - some on the floor; some elevated on racks. One other small warhead was limited to 12 in the same sized magazine. These were actually the smallest / lightest warheads - very limited shielding (tamping) due to size and weight constraints.
They weren’t going to critical or beyond, but interactions could cause degradation due to spalling, surface pitting, dislocation of other elements. They (nuclear engineers) were worried about longevity and reliability. Very precise tolerances (actually every warhead) were the rule. Everything about assembly/disassembly had stages of torque, patterns, total replacement of all bolts, nuts, crushable washers, and alignment checks.
IWNANE but those were the explanations without going into design and material details.
What I was getting at was that terrorists can’t really build an implosion weapon, but they can get some nastiness, and even some fission from a very unsophisticated device.
FWIW,
Rob
Even stealing or buying an implosion warhead wouldn’t mean they could set one off as intended. Other parts of the system are integrated into the weapon, it may not have a timing or fuzing system, and virtually all have a locking mechanism that’s pretty sophisticated.
A gun type system (see Hiroshima Bomb) is simpler and could be possibly be crafted but needs more highly enriched uranium than a Pu based implosion system.
By far the most likely scenario is a dirty bomb. Partially enriched radioactive materials; bundled medical devices, and the like detonated into small particles by conventional explosives. Public perception of radiation contamination and poisoning IMHO borders on panic - which would be the intent of the terrorists. An actual event would harm few people outside the immediate explosive area. No high level (beta/gamma/xray) radiation would occur. Ingestion and inhalation of radioactive dust is the main mechanism for having the radioactive material affect an individual. At that point, the main hazard is heavy metal poisoning rather than ionizing radiation. You would get some lung cancers down the road. Probably hard to distinguish from baseline cancers - again IMHO.
HBO’s A Dirty War explores this nicely. One of the most significant effects in the film was that a large segment of downtown London was rendered uninhabitable for 30 years. All in all, an excellent terror weapon. I guess this stuff is locked down tighter that one might think considering it hasn’t happened yet. Knock on wood.
FWIW,
Rob
Tell that to the families of these folks:
http://www.time.com/time/magazine/article/0,9171,955289-1,00.html
and these:
http://web.phys.ksu.edu/icpe/Newsletters/n35/index.html
I was referring to theft rather than accidents.
Those were examples of theft, though (or at least of unauthorized procurement). The problem comes with the fact that the public is so paranoid about nuclear materials and radiation, that a terrorist doesn’t need to use plutonium or enriched uranium to build a bomb in order to invoke panic. They can just use cesium or cobalt, and achieve less physically catastrophic events while instilling the same amount of terror and fear into their victims.
Also see Rhodes’ “The Making of the Atomic Bomb”. This page also has the account of Gen. Farrell holding the core. I believe Rhodes says elsewhere that the Pu core was gold and/or nickel - plated
Well, no one has yet stolen it for the purposes of making a dirty bomb (at least they haven’t set it off yet). Is it safe to assume that they are trying?
FWIW,
Rob
Rhodes actually probably got the details wrong on that point. He claimed that the plutonium hemispheres for the Trinity device were nickel plated (with gold on the matching faces), but Coster-Mullen’s subsequent - and on exactly this sort of nerdy technical detail significantly more authoritative - Atom Bombs (p48 in his 2006 version) points out that they were coated with silver rather than with nickel. Those for the Nagasaki and postwar Fat Man versions did use nickel, which presumably accounts for the confusion.
It must have been the most expensive object in the world at that point in time.
Yes.
There’s a comment in the book to the effect of “handle with care - it cost 2 Billion dollars.”
That’s overstating things a bit. IIRC, $2 billion was roughly the total cost of the entire Manhattan Project, which produced the Trinity implosion device (Pu-239), the Little Boy gun-type weapon (U-235), and the Fat Man implosion bomb (Pu-239).
Furthermore, the plants at Hanford and Oak Ridge were still churning out plutonium and uranium when the Nagasaki bomb was dropped, and produced fissile material for many more bombs that went into the arsenal over the next several decades. At least some of that was covered under the Manhattan Project’s wartime $2 billion budget. Say ten bombs’ worth. (Probably many more.)
So one might argue that, at the time of the Trinity test, that lump of plutonium had cost $2 billion. But as with all things, the price of fissile material goes down when you buy in bulk. So the subsequent production of additional pits lowered the unit price to a low, low $200 million. (Roughly.)
BTW, in the late 1980s, I met Phillip Morrison, one of the physicists who worked on the MP. He drove the pit (in a big wooden box) out to the Trinity site in his car. He showed me one of the O-shaped gold-foil “gaskets” they used to keep the two hemispheres of plutonium separate. (The flat surfaces were so precisely machined, so perfectly flat, that if they were placed together without the foil, they would soon fuse together and be inseparable.)
I was surprised at the size, because my reading had led me to believe that the pit of the Trinity device was about the size of a grapefruit. But it was only about 3 inches (8 cm) across, the size of a tangerine. :eek:
According to the Tinian “Pit Catalog” (Los Alamos document LAMS-381, page 12), the gold foil gasket used on the Nagasaki weapon core was identified as item “PC 4008…Shims, gold, .0005”, flat 2.75" O.D. x 1.375" I.D. 20 each".
The Pu core itself was 3.62" in diameter. It had a 1.0" diameter hole in the center for the 0.8" diameter Urchin initiator and a jet ring (that had a triangular cross-section) located on the equatorial plane. This jet ring presumably had a 3.62" O.D and a 2.75" I.D. based on the dimensions mentioned for the gold foil shim. The jet ring was not present on the Trinity core, which used, instead, many individual strips of gold foil shims both between the core hemispheres and the 4.3" diameter x 8.75" long uranium tamper cylinder that surrounded it. This cylinder was what was inserted into the 8.75" diameter uranium tamper sphere inside the aluminum pusher. All this comprised the pit used in both devices.
Yes, my book Atom Bombs does describe this along with the nickel and silver plating used on the Nagasaki and Trinity cores, respectively.
I Googled it, and this is definitely based on the story in the New Yorker that I remember. The story’s title was “Pu-239.”
The descriptions of the HBO movie make it seem much more melodramatic than Kalfus’s story.
I watched the movie a few weeks ago. Not bad at all. At the beginning a worker at a poorly-maintained Russian power plant is accidentally exposed to a dose of radiation; the plant operators falsify his badge’s reading and tell him he’s fired unless he admits that he caused the accident himself, and that he certainly won’t be receiving any insurance money. A sympathetic doctor slips him his real badge, proving that he actually received a huge dose, and he decides to steal some plutonium and sell it, to ensure his wife and son will have a future. Meanwhile, some petty thugs accidentally burn down the wrong store and their boss is ticked. They need to earn several thousand dollars within the next couple days or he’ll have them killed. When the two stories intersect, hilarity ensues! (Or tragedy and death. Whatever.)
ETA: For some reason, the movie is listed on IMDb as The Half Life of Timofey Berezin, with Pu-239 as the working title. Odd.