[nradov]

There is at least the possibility that fusion power could eventually be viable for privately owned civilian merchant ships. Fission power is a non-starter in that market due to concerns (valid or not) over security, terrorism, proliferation, and meltdowns. Even if someone builds a new fission powered merchant ship it would be useless because many nations wouldn't allow it to enter their ports.

Military fission power plants were never optimized for cost. They have always been hand built in tiny numbers with a focus on safety, durability, and maximal output.

[pclmulqdq]

Aren't the products of fusion equally radioactive? I get that we all have the idea of helium being the main product, but don't you get a lot of tritium out of the process? It's not quite proliferation, but it's not non-radioactive either.

[rnhmjoj]

Yes, tritium is radioactive but it has to be recycled and reused to continuously fuel the reactor. Every part of a fusion reactor is designed to minimise the retention of tritium, the actual radioactive waste will be materials activated by neutron radiation (neutrons are captured by nuclei, transmute the element into a radioactive one which then decays to a stable isotope emitting more radiation).

A small fusion reactor, being a powerful neutron source, will be a great risk for proliferation. It should be able to breed plutonium for nuclear weapons as much as it can breed tritium.

[sandworm101]

Which is why in "fusion" bombs the majority of energy still comes from fission. The fusion reaction is a neutron source to boost the efficiency of the fission reaction. A pure fusion bomb, if one could ever trigger such a thing without fission, would not be very efficient.

[coldburst]

For "boosted fission" and early thermonuclear bomb designs yes, but not so for the more evolved thermonuclear designs. Navajo (Operation Redwing, 1956) was 95% fusion, Tsar bomba (1961) was 97% fusion, Housatonic (Operation Dominic, 1962) was 99.9% fusion.

[arrobbiato]

My understanding is that the tritium is bred in the reactor and then consumed in the reaction. But most designs do have some amount of radioactive waste, including structural parts and reactor walls that suffer huge amounts of neutron activation.