Sunday, 20 October 2013

Nuclear reactor design validation and space industries.

I was chewing the fat over nuclear reactor designs with a chum on Twitter when something struck me.  One of the big issues in producing new nuclear designs is finding somewhere to build a prototype to validate the design.  There's lots of interesting, and potentially much safer and cleaner fission reaction designs being mooted, but most of them stay as computer simulations or paper designs because its increasingly difficult to get regulatory approval for building the reactors.

This is understandable in a way: few countries want to make it easy for companies to build dodgy designs that could leak radioactivity into the environment.  This means that reactor designs need to be carefully approved usually, which is very, very time consuming and thus very, very costly.

It also plays into the hands of the incumbent reactor manufacturers. Their designs are often evolutions of older, well understood reactors and the companies know the ropes of regulatory approval.  The regulators also know the companies and people involved.  These same companies also have a vested interested in not allowing some of the GenIV designs to be rapidly developed as they make quite a bit of their income from selling fuel rods for existing fission reactor designs, which some of the newer designs do away with (most notably pebble bed reactors and molten salt reactors using liquid fuels).

So onto my wacky idea: why not do initial validation of new reactor designs in space?  There are some distinct advantages:

a) If the design fails, a leak isn't going to be an ecological disaster.  If you put a reactor on the moon or an artificial satellite outside of Low Earth Orbit (LEO) reactor leaks aren't going to get back into Earth's biosphere terribly easily.

b) Space access charges are falling.  Companies like Elon Musk's SpaceX are reducing the price of getting mass into orbit.  At the moment most of this is targeted at getting equipment and people into LEO (for example supplying the ISS) but the basic launcher technology developments are ultimately aimed at getting mass to Mars.  Having a commercial funding opportunity get part of the way there would help the commercial space launch industry as well as the nuclear industry.

c) Whilst getting the equipment into space is expensive, it might be offset against the cost of the massively constructed containment buildings that are often required on Earth but wouldn't be required for the validation reactors in space.  Who cares if you've got minimal containment on the reactor if there's no biosphere to pollute?

d) Advanced robotics mean that you might well not need to send people up with these reactors, so you don't even have to worry about worker contamination/decontamination.

e) No extra nuclear waste will be generated on Earth, which is good seeing as Governments are still flapping about what to do with the stuff we've already generated.  If anyone is worried, provide ability to fire into the Sun!

There are downsides of course (probably lots of them considering this is just recording one of my brain farts!):

a) Getting radioactive material into space is nearly as tricky from a regulatory point of view as building the reactors.  Folk don't want radioisotopes being blown up all over the sky for some reason. Radiothermal generators have been sent out on space craft though so its not insurmountable, especially if space access charges mean that you can spread your fuel load into a number of small consignments spread out over many launches (so one launch failure doesn't mean a full reactor load of fuel being exposed to the biosphere).  Fuel containment and escape options may also help, especially as we have experience of equipment that has survived rocket explosions in the past.

b) Lack of gravity may affect some reactor designs.  This would require artificial gravity to be provided (simulated by rotating the reactor to give a 1g acceleration).  Reactor designs that don't suffer from this may of course be of interest for space exploration applications themselves.

c) Validation of a reactor design in space will still then require national regulators to accept the results.  This is unproven and may be just as costly/long winded as getting the prototypes approved for Earth bound deployment.

d) Hostile environment: whilst space doesn't have a biosphere to pollute, it does have micro-meterorites, difficult thermal gradients (very cold in shadow, boiling in the Sun), solar winds, etc, etc to deal with.  Lots of engineering fun to be had!

Well, just an idea.  Worth kicking out there for comment and thoughts though!