Quote:
Originally Posted by FlameOn
Reason I was pushing Thorium is the whole reaction chain produces byproducts that have a much shorter half life. It's considered safest among the list.
You are spot on with the rest of it... right now it's political will and too many people, and politicians, are too addicted to the fossil fuel crack to consider the eventual withdraw and consequences.
I'm hoping things turn around in the coming years, but not holding my breath. Why does Terrestrial Energy not qualify again? It should be only 5ish years out I thought.
|
Well... That's a misconception propagated by the LFTR movement on the Internet. The benefits you're describing have more to do with the sort of reactor than the fuel. Let me explain. First, let's talk about the reactors we are used to - high pressure, light water cooled reactors powered by uranium rods (LWR).
A reality of light water uranium reactors is that the fuel pellets in the rods can only be partially used. You can't control which atoms transmute into plutonium, so they get points that become too hot for the metal casing so they become a meltdown risk. Because of this, they take rods out before the bulk of the fuel is done providing energy. Some of this fuel is recycled, but it is quite difficult to do that with the way the pellets are fabricated. The resulting "waste" is largely a mix of elements that could still be used for energy production if we had a machine that could deal with the temperatures and radiation activity. It's made out of three main things: fission products, unused uranium, and plutonium.
The fission products are the true waste of fission reactors, like COx, NOx, SOx and particulates are for burning fossil fuels. They have high radiotoxicity but short half lives, as you describe. They need storage for only 300 years to be safe. This is a very manageable issue, and the potential externality becomes permanently contained. Not a lot of energy sources can make that claim.
Unused uranium is not harmful whatsoever. Natural uranium is very common in our soil and things like granite countertops. It is not harmful to touch. It is difficult to separate from solid fuel pellets though.
Plutonium is the third major component and is the legacy issue everyone worries about. It's co-production is also one of the reasons LWR technology was the first to emerge as a widely used technology. LWRs were the result of a military need and plutonium (along with highly enriched uranium) were key elements of atomic bomb production. LWRs weird operating characteristics are also perfectly suited for use in submarines. Anywyas, plutonium is highly radiotoxic and has a very long half life which means it needs to be stored for hundreds of thousands of years before it is safe. This is why we look at building repositories in yucca mountain where it has been geologically stable for millions of years and people say things like nuclear power is a problem for long future civilizations. What plutonium actually represents is another source of unused fuel.
The way we do it is a lot like taking a log off a fire when it is only half burned, and then holding onto the burnt logs in a big pile nearby ... Indefinitely.
The same way if you put gasoline on a dish and ten burn it, it's a very incomplete combustion and it looks really dirty. Put it in a highly tuned internal combustion engine and the reaction is more complete and less wasteful. Or an advanced coal plant, or a combined cycle gas turbine. Our bodies are the same too - eat well, exercise, and we use the energy available in the food and poop less... You get they idea. Machines need to be refined in their designs and workloads to use their fuels as best as possible to extract maximum energy and leave as little waste as possible.
LWR haven't really changed in decades. Their costs have escalatied over the years because with each incident, safety systems get mandated but the basic technology that leaves all the issues above remains the same. Because the pressures of these things are so huge, massive heavy steel containment vessels and concrete structures need to be built with big energy production to make it economic.
What if we had a machine that could use fission fuels more completely, didn't run at high pressure, but could be designed with smaller power outputs? Nuclear power becomes a very different animal.
Molten salt reactors are a different type of machine that put the fuel in a liquid solution. The system operates at atmospheric pressure and high temperature. When in solution with the salts, they are extremely stable and non reactive, the radioactive elements are also free to move in the reactor core. What this means is that the machine can allow the reaction to occur more completely, including using more of the uranium and even the plutonium as fuel. Because it is an aqueous solution, separating the fission products out for long term storage is much more simple and the uranium/plutonium left over can be put into another batch for use as fuel instead of being a legacy issue. This is huge.
Now for thorium. Thorium can also be used in light water reactors, and it is used in a few repurposed CANDU reactors, a demonstration plant in Noreay and India is moving to use this sort of technology as well. Thorium is an order of magnitude more abundant than uranium, but it is not fissile on its own - it is only fertile. This means it needs donor neutrons to bump it up to uranium 233 before it can sustain a chain reaction. It is true that this fuel cycle produces a different mix of fission products and less plutonium 239 (the isotope that is used in weapons fabrication).
Thorium used in light water reactors as mixed oxide fuels still result in a lot of the issues described above. They are pursued because thorium is abundantly available and very inexpensive.
There is a lot more to the variations in reactor design possible, but Thorium can also be used in a molten salt reactor and used more completely.
So the benefits of less waste and managable storage are less attributable to thorium itself and more attributable to a liquid fuel reactor like the MSR.
With the IMSR, the heat output is very high and is therefore suitable as a process heat source for things like steam generation, hydrotreating, desalination, etc. so it can be integrated with conventional petroleum plants to reduce their consumption of methane or coke to fuel their processes. This makes them less impactful environmentally, and more economic due to low fuel costs and higher utilization of feedstock (lower cost, higher production per unit of input).
Someone else asked how small they can be made. Physically the reactor is about 3-5m in diameter and 9m in length. It fits on the back of a trailer truck/rail car and has the same footprint as a steam generation facility would have on a SAGD plant site. We are designing out electrical output as 29, 300 and 600 MWe. They can be built in modules so a plant can expand its effective output by building additional core units. Each core unit will run for about 7 years before it gets swapped out compared to an 18 month rod run for LWRs. Anyways AI could blab on about this forever and I've already posted a lot.
Well, we are qualified, PM me for more details. I shouldn't post that stuff publicly.
Quote:
Originally Posted by Fozzie_DeBear
The Government has been investing in many technology based innovations...it's just not widely appreciated by the public
Google CCEMC or Alberta Innovates Energy and Environment Solutions for a sample of investment.
This is the space I work in. Last week we visited a lab of a nanotechnology researcher in Edmonton who is working on a solar panel that can directly change water into H and O2 also she is working on a system for turning CO2 into methane (her name is Jillian Buriak if you want to see her work).
There are literally tens of millions (easily) spent on basic research, applied research and technology company support every year by the Government of Alberta. Usually delivered by a bunch of arms length organizations who fund research at Universities and Companies.
John Q Public rarely learns about this cool #### though.
|
The reason John Q. Public doesn't hear about them is because there is a weak back end in commercializing technologies. It takes extreme political/public will to roll out publicly funded r&d into anything big, or private interest scanning the IP 4 Sale lists that national labs roll out every once and a while.
Also, our media sucks. All of the reports are public and available but it's not reported in a way that is interesting, consumable or exciting for folks.
