Last week’s news of significant North Korean ICBM advancements was followed by Hawaii resuming missile air raid warnings. They’ve also reopened fallout shelters.
We are reaching the time when there’s a realistic threat of a North Korean weapon hitting New York City. It may not be too paranoid to encourage any loved ones who live there to think about leaving – and, perhaps, reread my recent article detailing how you’d easily survive such an event if you live here, provided you or some cooperative friend invest $2,500 in creating a practical air-filtration system in the basement. You’d only need to stay there for two weeks.
The problem is radiation. While a true hydrogen bomb creates a relatively clean explosion that results in relatively modest fallout, bomb designers long ago realized that fusion’s extreme heat and profusion of fast neutrons could efficiently initiate fission in materials that ordinarily couldn’t sustain fissioning, like inexpensive Uranium-238. So, very quickly, they learned to surround every H-bomb in a uranium casing. Now they had a multistage explosive: a fission/fusion/fission process. This has been the basic design of every nuclear weapon for the past 60 years. It’s presumably what the North Koreans are using, too.
According to Hans Bethe, in his 1954 history of the H-bomb, Edward Teller’s original idea was to employ a small atomic fission bomb to start the fusion process in a nearby cylindrical tank of deuterium, which contains a “sparkplug” of highly fissionable U-235 at its center. This alternating deuterium and uranium lets an atomic bomb’s fissioning ignite the deuterium fusion, whose fast neutrons then ignite fissioning in the uranium casing. This arrangement produces the maximum power.
But most of this energy comes from fissioning, which is extremely dirty and produces lethal fallout that spreads far and wide. We first saw this in the powerful 15-megaton Castle Bravo test of March 1, 1954, which famously sickened Japanese fishermen. Nonetheless, this principle was promptly weaponized, as when 500 copies of this three-stage fission/fusion/fission weapon (the Mark 41) was deployed on B-47 and B-52 bombers in the 1950s and 1960s. Its 25 megatons made it not only the most powerful single weapon in the US arsenal, but also the dirtiest.
Eventually the US and the Soviet (now Russia) stockpiles decreased from their 1960 maximums, partly because of miniaturization, SALT treaties and the use of MIRVs, or multiple warheads on a single missile. As of 2015, the US had “only” 7,100 active nuclear weapons and 1,890 separate means of delivery, including bombers, submarines and MIRVs. But despite being called H-bombs, every single one uses fission for most of its explosive energy, and would therefore create widespread radiation fallout.
It’s a big reason why a nuclear war would be a global catastrophe. It’s too bad that, despite groups like the Union of Concerned Scientists expressing alarm, the public seems largely oblivious to a threat that is as real as it was a half-century ago.
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