Recycling used nuclear fuel – Argonne research explained in 4 min video
One of the most frequently used arguments against using nuclear energy is “the waste issue.” When people ask me, “what do you do with the waste”, my standard answer is “recycle it.” The truly curious then ask for more information. A few days ago, Nuclear Street shared a video produced by Argonne National Laboratory that explains their ongoing research into pyroprocessing.
This video was first posted in May, 2012. Even if I have linked to it before, it is worth watching again. It is encouraging to remember that there are plenty of options that enable nuclear energy to have an amazing potential for future improvements by following the adage of “reduce, reuse, and recycle” to shrink an already minuscule quantity of waste per unit of energy to even smaller sizes and easier to handle forms.
There is a communications risk associated with telling some people about the incredible potential associated with nuclear fuel recycling. The video alludes to the challenge; if we can recycle the used material produced by our current fleet of reactors at a reasonable cost, the enterprise would reduce or even eliminate the need to mine uranium. If the process lives up to the promise, it might reduce investment interest in developing thorium based reactors.
I ran into an example of this challenge during my involvement in the issue of uranium mining in Virginia. At one meeting, I had a hallway discussion with a few of the attendees who were opposing the effort by Virginia Uranium to have the current moratorium lifted. My conversation partners told me they were not strongly opposed to using nuclear energy, they were, however, concerned about the effect of allowing uranium to be mined near their homes, farms or businesses.
During the next meeting I attended, several of the people who spoke in opposition to the mine introduced the idea that the mine was not needed because nuclear fuel could be recycled. They were not the same individuals that I spoke to, and there is a strong possibility that my introduction of the recycling notion had nothing to do with it being used as an argument against mining.
However, I had to think for a little while and wonder if my enthusiasm for recycling was being used against my enthusiasm for making beneficial use of a large natural resource. I often cringe when fellow enthusiasts for nuclear fuel recycling or thorium reactors talk about how their technology will eliminate the need to continue mining uranium.
Mining of all kinds is absolutely necessary to support a vibrant economy; that statement has been true for hundreds, if not thousands of years. There is a need to do it with care and concern for worker safety and environmental impacts, but mining and using valuable material is one of the most reliable ways to increase society’s overall wealth.
The other thing to remember is that a recycling infrastructure will not develop rapidly and it will certainly not develop at all without dedicated people who are willing to invest time and dollars in a long term process. During the decades in which recycling is entering the market, there will be plenty of need for newly mined fuel. In fact, I believe that conclusively demonstrating that it is possible and advantageous to recycle used fuel will increase the demand for new materials and increase its market value.
The “waste issue” would be proven to be a chimera. We could stop describing the potential and instead point to real hardware being constructed and operated to turn waste into useful energy.
It is exciting to know that a tiny pellet of uranium dioxide fuel contains as much energy as a ton of coal, three barrels of oil or 17,000 cubic feet of natural gas. Just think how valuable and exciting it would be to multiply those three comparisons to fossil fuels by a factor of about 20 and to also realize that the pellet represents only about 1 part out of 9 of the mined uranium due to the need to enrich the fuel.
Energy is the ability to do work. Power is the amount of energy used per unit time. Humans could be doing a lot more work at a much faster rate to make the world a better, safer and more prosperous place to live if they had access to virtually unlimited quantities of low cost, emission free, reliable power. Instead, our potential is being constrained by the false assumption that energy is scarce and should be conserved at all costs.
Opponents of nuclear contend that recycling nuclear fuel creates a secondary waste stream, namely liquids and resins. They also contend that these waste problems are unsolvable. As with so many of their claims I have difficulty believing them. The impressive flux density of nuclear (as Brian Mays’ post indicated) combined with an equally impressive array of applications (desalination, hydrogen production, district heating etc.) demand that we recycle used fuel. Not doing so would be like buying 20 litres of fuel from a gas station and being told you can only use one litre of it.
We also forget to talk about transmutation in te waste debate … Hey, the french went out for a bite (they have 3 hour lunches mind you) and tried bombarding neutrons on radioactive Technecium 99.
When they came back, they had Technecium 100, not harmfull at all.
So let’s not forget transmutation for liquids and resins.
You wouldn’t have Tc-100; its half-life is only 15.8 seconds. However, the decay product Ru-100 is stable, and Mo-100 has a half-life so long (8 billion BILLION years) it might as well be.
I don’t think so. Fast-spectrum reactors do well at disposing of Pu and beyond, but need a high fissionables inventory so can’t scale up by breeding very quickly. Thorium-based thermal breeders can be built with less than a ton of fissionables per GW(e) and may be able to breed up at 5% a year; U-Pu is closer to 2%/year†.
The 60,000-odd tons of SNF in the US inventory has ~600 tons of Pu in it, enough to start maybe 30 GW(e) of LMFBRs. That would be a big jump in US nuclear generation, but a long way from where we need to go. The advantage is that it’s about as ready TO go as anything we’ve got; any US-built thorium MSR is going to take quite a bit longer to hit market due to 44 years of wasted time.
The problem with Th-U waste is production of Np-237, which is fuel for the fast-spectrum reactors. Thus, the fast-spectrum reactors still have a job even if thorium becomes free (as uranium from SNF and DU will effectively be).
† The high inventory and consequent slow breeding rate is partly due to a projection of 3 core’s worth of fuel per reactor: one in use, one cooling and one reprocessing. If the cooling period could be shortened and the reprocessing cycle staggered with another reactor or two, maybe the inventory could be reduced and the growth accelerated. If you can get the increase up to 3% of inventory per year, the doubling time falls from 35 to 23 years; at 4%/year, it falls to 18 years.
By the way: Has anyone here ever heard of this idea: A molten salt reactor with lead cooling in the fast spectrum? The source I stumbled upon promises a 4 year doubling time and an EROEI of over 2000. They call it Dual Fluid reactor.
“The efficiency of the MSR is reduced by the double function of the fuel to act also as coolant. As a result, the molten salt used had to be diluted in order to limit the power density, otherwise the heat could not be removed fast enough. Furthermore, salts with low melting point are necessary for the effective utilization of a heat engine. In addition, the salt has to circulate fast for efficient cooling and that, in turn, prevents any on-line reprocessing of the fuel. The fuel, thus, needs to be processed off-line (but still on-site) at regular intervals. Off-line processing of the fuel requires long shut-downs, further reducing the efficiency of the overall system.”
Is this a new idea? It sounds too good to be true. Where are the downsides? Are there other sources about this reactor?
I’m not a nuclear engineer, but I can think of a number of engineering difficulties with this concept:
1. Possible corrosion of the salt container by the lead alloy coolant.
2. Damage to the heat-transfer materials by fast neutrons.
3. Scheme allows the possibility of a loss-of-coolant accident.
If I understand correctly, a fast-spectrum molten-salt reactor almost requires the use of molten chlorides, not fluorides. Using the fuel salt itself as the coolant eliminates any issues of heat transmission from salt to coolant, and also of loss of coolant. Whether there are major advantages to be gained from the complication… I am not qualified to give an opinion.
The Indian PFBR uses 2 tons of Plutonium for 500MW of power. This gives 4 tons/GW. Even if we consider the PHWR plutonium to be better than the plutonium from LWR fuel, 5 tons/GW should suffice. That gives 120GWE of fast reactors in the initial build, nearly equal to present installed capacity of LWR’s in the US. Things are more economical in bigger reactors or in the MSR.
The best solution in any case is fast spectrum MSR as the gen IV reactor.
Transatomic Power presenting at Energy Innovation Summit tomorrow evening in Washington D.C. http://www.arpae-summit.com/Agenda/Future-Energy-Pitching-Session list of the eight presenters at the bottom of this page.
http://www.transatomicpower.com “Power from nuclear waste. Transatomic Power’s Waste-Annihilating Molten Salt Reactor — WAMSR…”
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