What to do with waste - launch into space?
‘Why does the world store nuclear waste and just not shoot it into the Sun or deep space? – Jason, age 16, Mackay, Queensland.’
This is a particularly grown-up question and deserves to be answered carefully. To do so, let’s divide it into two parts - storing nuclear waste and shooting it into space - and answer the second part first.
So, firstly, launching stuff is expensive because it’s all about mass. Rocketry has steadily improved and now we even have reusable rockets, but it still costs nearly $1,000 per kilogram and this is practically all saved for communication satellites, scientific equipment and supplies.
Once in orbit, transferring out of orbit and into space can be even more expensive, because it requires accelerating either faster, out in front of Earth, or back behind the planet (to slow down and head towards the sun). Because F = ma, the required force must be supplied by an amount of propellant proportional to the mass. Nuclear waste - the used fuel out of reactors - is mostly uranium, the heaviest naturally-occurring* element. Therefore, a lot of propellant is needed.
So, the idea is really expensive, but this isn’t to say this kind of material hasn’t been launched before. The amazing pictures we’ve received from probes like Voyager, Curiosity, Cassini and New Horizons were thanks to plutonium-based power supplies built on Earth. These were also used on the moon, and when Apollo 13 struggled back to Earth its Radioisotope Thermoelectric Generator was dropped into the Pacific, and is expected to remain intact for 10 half-lives of Plutonium (~870 years). Other similar power sources have also been lost on re-entry.
Next, the used nuclear fuel from commercial reactors. This is a distinct type of ‘nuclear waste’, and the most important thing is it’s a by-product from nuclear power plants; their actual product is about 10% of the world’s electricity. A standard reactor may produce less than thirty tonnes of used fuel in a year. So this is already $30 million to launch it just to orbit, even before considering the weight of steel and concrete shielding it’s normally kept in for safe management!
There was a royal commission in South Australia which looked really closely at used nuclear fuel, and it noted for the highest level of nuclear waste:
Within 500 years, the most radioactive elements in the used fuel will have decayed. At that point the radiotoxicity is dominated by the presence of radionuclides of plutonium and americium, which have very low solubility and mobility when underground, given their strong tendency to adhere to surfaces of rock and clay. After 1000 years, the radiotoxicity of the used fuel is only about 1.5 per cent of initial levels following discharge from a reactor, and the rate of heat output is comparable to that produced by an adult human.
Australia produces a small amount of this material, a by-product of our nuclear medicine industry. Getting it reprocessed in France is straightforward; the French separate and keep the really heavy components to recycle in their power plants while the final waste (containing ‘fission products’) gets shipped back as an inert glass material encased in a cask designed to withstand train collisions.
This waste with reduced radioactivity is classed as Intermediate Level Waste and can be stored in hardened canisters above ground while a permanent solution is developed (see picture below). This Australian nuclear waste is currently a part of the process to site a National Radioactive Waste Facility that will manage Australia’s Low and Intermediate level waste. Three sites nominated by local residents at Kimba (2) and Barndioota (1) are undergoing the stages of assessing the development.
“The opportunity for employment would be bonus for Kimba,” said Margaret Milton, who lives in one of the possible volunteer host communities for the national waste management facility. “Can you imagine the boom which a facility of that magnitude would do for the town of Kimba? I can see opportunities in science in the school for the kids... New infrastructure, better internet and mobile services, improved hospital facilities and wow we may even get a full time doctor.” Like all residents she has had the opportunity to visit Australia’s nuclear research centre and ask its professionals all the important questions.
As for High Level Waste, the royal commission also prompted research by some Adelaide scientists (including Dr. Ben Heard, Bright New World founder) into the feasibility of taking custody of used nuclear fuel from international partners with the aim of recycling it in Integral Fast Reactors.
This would make a heck of a lot of low-emission electricity while also dramatically reducing the effort involved in managing the by-products - effectively “solving nuclear waste”. The overwhelming hurdle is Australia’s decades-old prohibition against building any sort of nuclear plant.
The other result was a suggested price of $1,370 (or more) per kilogram of used fuel paid to Australia to manage and permanently dispose of it - rather than being a cost, it could be income! South Australia is a globally-recognised example of this by turning plastic waste into paid recyclable material with the container deposit scheme.
Launching used nuclear fuel into space seems like a reasonable suggestion only until we start to look at the numbers and the alternatives which are available. It would be better if we could reuse and recycle it here on Earth reducing the levels of radioactive waste, to extract even more plentiful clean energy.
This is the pinnacle of the environmentalists mantra “reduce, reuse and recycle”.
(This article was inspired by Jason’s excellent question originally posted at The Conversation)
Osk Archer is a PhD. qualified process chemist, energy efficiency professional and enthusiastic ecomodernist based in Adelaide, South Australia. Dr Archer has earned global respect and recognition for his contribution to the environmental conversation though his excellent blog 'The Actinide Age'. He provides research, analysis and public speaking support to Bright New World, when he is not busy with the Australian Insulation Standards Committee. You can follow Osk on Twitter as @OskaArcher and read his current work at The Fourth Generation Blog http://4thgeneration.energy.