With an 84-year half-life, even after 200 years 20% of the radioactive material remains.Altorin said:according to wikipedia, depending on the isotope of plutonium it ranges from 84 years (238pu) to 8,080,000 years (244pu).
If it's the 84 year halflife isotope, most of the radiation present in fallout would dissipate in about 200 years. *shrug*
Of course, technically speaking, the largest component of nuclear fallout is short-lived radioisotopes resulting from nuclear fission, not unexploded Pu-239 - for comparison's sake, the fallout from the Chernobyl disaster has a half-life of roughly 4 years. After 200 years, the radiation from such fallout would be practically undetectable.
Not that any of this matters, considering the science in Fallout is intentionally fairly soft.
It would take way more than 55,000 bombs.Altorin said:I wonder how many nukes it would take to literally break the world in half... like if you dug down deep enough and just planted nukes down there, how many would it take to actually split the world in two? I would imagine it wouldn't take 55,000
Planets are surprisingly sturdy things, and take vast amounts of energy to destroy or even seriously damage. For example, the Earth's gravitational binding energy 224,000,000 YJ (i.e. 2.24e32 Joules) - this is the amount of energy required to flat out explode the planet. (Any less that that and the resulting fragments would recombine due to their mutual gravitational attraction.) And even just cutting the planet is harder than it sounds, because most of the Earth's volume is liquid, and the crust is not one single piece, but several smaller sheets of rock held in place by friction.
Even if every single one had a yield of 100 megatons (the theoretical maximum yield of Tsar Bomba, the largest nuclear weapon ever tested), 55,000 bombs adds up to only 230 ZJ (i.e. 2.30e23 Joules) - only one billionth of the Earth's gravitational binding energy. That's about half the energy released by the Chicxulub impact (aka "the one that killed the dinosaurs") - and while that impact caused massive tsunamis and triggered earthquakes and volcanic eruptions all around the world, it's only lasting influence on the Earth's structure is a 110-mile-wide crater. A ring of 55,000 100-MT weapons would dig a hell of a trench (and probably trigger global seismic activity), but that trench wouldn't even break through the thinnest parts of the crust, much less go all the way through the Earth. Nasty planetary scar yes, planet cut in half no.
And of course very few, if any, of those bombs would have yields anywhere near 100 MT. The highest-yield weapon currently in the US stockpile is only 1.2 MT. Even the single Tsar Bomba that was ever built only had a yield of 50 MT.