Geoffrey Lean: stick, end of, wrong, again

This is because it will increasingly be trundled around countries, and shipped across the world, to fuel reactors. The Earth has limited amounts of usable uranium that will not take more energy to mine and process than it generates – so the industry wants to eke the supply out by mixing it with plutonium. Indeed, such so-called mixed oxide (Mox) fuel is already used in some reactors.

The plutonium comes from separating it and uranium out of nuclear waste at reprocessing plants such as Sellafield. Until that is done, it is impossible for terrorists to get at it, because it is mixed up with the lethally radioactive waste. But extracting it from Mox fuel, experts say, is relatively simple. Worse, they add, building a crude bomb is not that difficult either. Students with no specialist knowledge, using only the open literature, have produced workable designs.


The aim of MOX is exactly the opposite. It\’s to take bomb making plutonium and turn it into something less easy to make into a bomb.

4 thoughts on “Geoffrey Lean: stick, end of, wrong, again”

  1. He is part of the Decline and Fall of the Telegraph. Its infantilisation is not shown only by all those air-headed women it’s hired.

  2. I see Lean is also claiming, without sourcing, that we have had one of the warmest winters in Northern Europe on record.

    Oh well, at least we have Booker to shoot down
    this stuff.

  3. So Geoffrey Lean thinks building a plutonium bomb is easy does he? You don’t need to read any further than that to know he doesn’t understand the first thing about nuclear weapon design. It is the case that a uranium bomb can be made fairly simply. Little Boy, the bomb that was dropped on Hiroshima, was not even tested before first deployment. Fat Man, which destroyed Nagasaki, was tested at the Trinity site in New Mexico precisely because, with billions of dollars in development costs and some of the smartest men on the planet behind its design, we were still not sure it would work.

    Uranium can be induced to involve itself in an explosive chain reaction by self-assembly of two or more sub-critical masses into a super-critical mass. In the Little Boy design, a plug of uranium was fired by a black powder charge down a gun barrel into a uranium target. For this reason, such weapons are called ‘gun type’ bombs.

    You cannot do the same trick with plutonium. Plutonium is created by the bombardment of uranium 238 with neutrons or neutron-containing particles like deuterons. A neutron is captured, forming uranium 239, which then decays to neptunium 239 and then plutonium 239. This is the primary bomb-grade fissile material. The problem is that occasionally two neutrons are captured by a nucleus, which after subsequent decay forms plutonium 240. Pu 240 has a much higher level of spontaneous fission than Pu 239, and this extra activity means that sub-critical masses of plutonium cannot be assembled fast enough before the reaction blows the bomb apart, causing a ‘fizzle’ yield.

    Instead, to detonate a plutonium bomb, the device uses the implosion technique. In this design, a spherical core of plutonium is encased in explosives, which are then detonated at several points on the surface simultaneously. A shockwave travels inward, compressing the plutonium to super-critical density, at which point it explodes. The problem is, simply wrapping a spherical shell of explosive round the core will not work. The detonation front from the points of detonation spread out hemispherically, and thus do not impinge radially on the core. The core material will simply squirt out along the lines where the shockwaves intersect. Instead, a mixture of fast and slow explosives was used. By carefully shaping these two types of explosive, the shock fronts can be reshaped into a radially-compressive pattern. Modern designs use a single type of explosive and an inert insert called a waveshaper. Collectively these are known as ‘explosive lenses’.

    An extremely large portion of the Manhattan Project design effort lay in calculating the precise shape of these explosive lenses (this essentially involves numerical modelling of the hydrostatics of detonations, which is why the computer programs used are called hydrocodes.) Another large portion lay in the fabrication techniques to make them. A single bubble, void or crack in one of the lenses would have caused failure. Each lens had to be detonated to within fractions of a microsecond of the rest (you need krytrons and exploding bridgewire or slapper detonators for this.) The explosives had to be very dimensionally stable so that they would not slump or sag before use. All of this took the mightiest technological power on the planet years to do.

    Non-state actors are, at present, completely incapable of creating implosion-type bomb designs. It’s hard even for states to do. Anyone capable of using the tools available in a standard machine shop can make a uranium bomb. It takes a government to make a plutonium bomb.

    In summary, Geoffrey Lean is an idiot.

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