In all fairness, I still remember the hard realities I learned when I was the coordinator (for about three years) of the DHS(DNDO)-NSF joint initiative on research to help us cope with the risk of nuclear terrorism. There are lots of nice safeguard programs at airports, for example, to try to keep out nuclear materials -- but in the end it was clear that "The US is like a house with 20 doors, 10 locked and being locked ever tighter, but 10 swinging wide open with little prospect of our being able to close them." By far the main factor which has kept us from having a nuclear type of incident, which would vastly dwarf the things we recently saw in Paris, is the limited supply of nuclear materials and technology around the world. Certainly the ratio of risk to the US to kwh generated is greater for kwh generated OUTSIDE the US than for kwh generated inside the US -- which creates a paradoxical situation: US national security demands that we work especially hard to make non-fission non-CO2-emitting power more widely available, at lower (unsubsidized) cost
OUTSIDE the US. But it's hard to do that if we don't do the most we can inside the US.
As I see it, the misuse of nuclear technology (mainly weapons, terrorism and proliferation) is one of the two greatest threats to the very existence of the human species, along with aspects of climate change (future H2S emissions from oceans) which we need to better understand. If we value survival far above other mundane variables, then the challenge is how to avoid BOTH risks, as much as possible. Probably IEEE is not the best place to get into all the gory details of the nuclear pathways to extinction, as they involve the behavior of political actors and national security issues, but it should be clear for the record that some of us would not want to reduce the probability of human survival. (Still, I do see nuclear fusion in space as much safer than fission on the ground, as few terrorists could accomplish a raid up to geosynchronous orbit!)
In response to a question about fusion, I followed up:
Serious people have considered the possibility of fusion in space for a long time now.
Of course, there are many forms of fusion, and there are lots of debates between them.
Perkins of LLNL predicted back in 2003 that LLNL (NIF) would reach "breakeven point" with laser-induced fusion about ten years sooner than the big tokomak programs like ITER. People have objected that the NIF laser cost many billions of dollars to complete -- but the main costs were things like California real estate, construction, permits, and capacitor banks to pump the lasers. By contrast, in space, it is possible to use lightweight mirrors to OPTICALLY pump the required types of lasers. Years ago, Richard Fork (who worked a lot with Willis Lamb, famous for the Lamb shift) worked with me to develop a design for a high power laser which could be assembled in space, massing little enough that a single shuttle launch could get it into orbit. NASA long proved out the required types of lightweight mirrors... much easier in space, where wind and fighting gravity are not issues.
John Ragan of Entech was one of the leaders of EPC recently, and his company was also a leader in developing mirrors/lenses BOTH for space use (funded by NASA's previous SSP program under Mankins) AND for earth use (funded by DOE). It's my understanding that proven lenses for use in space were about 500X, and lighter in toto than the 50X which were the best state of the art for earth.
Back around 2008, I had a chance to interview one of the laser physicists working with Perkins' group. While many US (and Brazilian) laser people said they could design and prove the kind of lasers Perkins would need for use in space, that guy said the Chinese are far ahead, that they lead major international conferences on that type of high-power laser, and that I should not worry about security levels. I am sorry that I was unable to persuade NSF management to fund a design competition for that kind of high power laser... but management does turn over, as does the appetite for new areas.
I am especially impressed by Perkins' designs for pellets which would be mainly deuterium, yielding proton momentum (i.e. electric current) as 70% of the outgoing energy! And in space, neutrons turn into protons in about 12 minutes. No need for giant steam reactors.
No one knows for sure whether this would be cheaper than any form of fusion on earth, but it looks promising enough it would be well worth the effort. People have also discussed in-space use, including propulsion.
However -- as with everything else in space, the cost-benefit tradeoff depends hugely on the cost to LEO. That is the bottleneck for many, many things! I usually discuss RLV first, because of how urgent and how clear it is, objectively... but there are ever so many more entertaining if unproven possibilities which branch out from there!
Best of luck,
P.S. They also warned me that pellet design for NIF is a whole lot more an object of caution for national security. I personally am very interested in new things we could do in that space as well, but haven't yet developed the right communication pathways.
There may be those who imagine that this is an issue for the West, and not for China. But I have seen what goes on in Xinjiang, and networks connecting to Xian (which in a way is to China what Belgium is to the EU -- think of this month's issues in France.)