Aviation experts in the U.K. are arguing that the industry should push to convert their planes from using fossil fuel to using nuclear energy, an idea that's sure to illicit a visceral “holy crap, god no!” reaction from the get go. But while it's hard to separate the idea from the mental image of flying hydrogen bombs, there ARE actually a lot of good reasons to go nuclear in the sky. The most pressing one is that changing to nuclear will help reduce the amount of emissions from planes and keep them flying in the air longer. A plane sipping on nuclear energy could take off in London, land in Australia, and then go to South Africa without needing to refuel, and it'll have zero impact on the atmosphere as well. Plus, the safety risks we tend to knee-jerk envision with nuclear are tied more to its image in popular culture than any real scientific facts. Nuclear submarines have been around since the beginning of the Cold War—when was the last time you heard of an actual meltdown related to one of those? Now compare that to the tons of other fuels that have been leaked into waters over the years. Safe nuclear planes have been feasible since the 1950s, but lost favor when the military decided to start building intercontinental ballistic missiles instead. While there are a few genuinely valid concerns we need to address before we actually let nuclear-powered planes take off—how to automatically jettison the reactor in case of a plane crash and what to do with spent fuel, for instance— there's no reason why we shouldn't at least hit the power button on research. [Times UK via Crunchgear]
The shielding is going to be my primary concern. However good it is—and it's going to have to be very massive and bulky (to shield against gammas and neutrons)—there is going to be some measurable exposure to passengers. On a single flight they should be able to limit to 1 millirem (1 mrem)... I hope. Cosmic radiation exposure already gives you ~1 mrem per flight. But I would have to think that pilots, and frequent fliers, would have to limit the number of flights on nuclear aircraft each year just to keep exposure levels at very safe limits. And, the limits are even more stringent on pregnant females or children.
Annual exposure limits for "radiation workers" are 5000 mrem per year. For the public, 500 mrem per year. For a fetus, 50 mrem in one month. For this reason, I would have strong reservations about letting a pregnant female take multiple nuclear aircraft flights during pregnancy. Heck... if they can't get exposure levels from the reactor to 1-2 mrem per flight, I'm not gonna fly nuclear.
There is a competing school of thought: the radiation hormesis folks.