ThinksMarkedly wrote:
Also, would a 300-gigation warhead be detectable on sensors? Wouldn't that thing leak radiation like there's no tomorrow?
I don't think so, probably not even with today's technology and definitely not with the Honorverse tech.
Today's fusion nukes, AFAIK, are all fission initiated (and often induce a secondary fission in their outer casing). You need the fission to generate the vast amount of high energy X-rays that get directed into the heavy hydrogen isotopes to initiate their fusion. Most of the radiation is in the uranium or plutonium in the fission primary, with a little being in the tritium of the hydrogen secondary. (And then often the outer casing is more uranium, which all the neutrons from the fusion will trigger additional fission in)
However even today's nuclear warheads aren't very radioactive; too much internal radiation could cause them to degrade or fissile before being asked to detonate. In fact there are isotopes that need to be kept out of the core or their excessive radiation will 'poison' it and degrade or eliminate its ability to function as a nuclear weapon. And so while sensitive radiation detectors can detect them from short to moderate distances (maybe a few dozen meters) I don't think even in the vacuum of space you'd be able to reliably detect them from even 10s of km away.
But the Honorverse warheads wouldn't be even that minimal level of radioactive; they may not be radioactive at all until initiated. They're described as a pure fusion gravity implosion design - relying on gravity forces from one-shot overpowered grav generators to rapidly pressurize (and thus heat) the fuel similar to what the mass of a star would do. Depending on the pressures they can generate with their gravity pinch they might not need any tritium in order to cause the hydrogen (or hydrogen and deuterium) to fuse. There might literally be no radioactivity to detect until after the grav implosion compresses the fuel to the point of self fusion. But in any case they wouldn't be putting out dangerous, or even readily detectable, levels of radiation until the moment they trigger the warhead.
Their power output would be determined by the amount of fuel (which has little to no radioactivity) and how far their grav generators can compress it before there's time for the fusion reaction blows the warhead, and those generators, apart. A higher yield warhead would likely be barely, if any, more radiative than a small one.