Thorium | Next gen nuclear power

[Milo]

I am very interested in the possible rediscovery of fission energy through molten salt thorium reactors.

If you don't know about it; a quick primer below.

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As much of the innovation in this area is going on overseas, I would hope that people on here would post news that they get on developments.

[Typhoon]

Added the descriptor "Next gen nuclear power" to clarify the "thorium" context.

Molten salt nuclear reactor

[crashtech]

There are several very promising Gen IV reactor designs, yet the only reactors currently being considered for construction are of an advanced PWR design, better than previous designs, but still not "walk away safe."

I think getting people educated about nuclear has been and will continue to be a great challenge. Even simplified explanations require more understanding than the average person has, and there has been much fear of radiation and nuclear power instilled in the general populace by activists.

As for myself, I fear living with no electricity much more than I fear the tiny risk of radiation exposure, but then again I am in possession of enough facts to make that decision rationally.

[Milo]

Well, hopefully that India and China have nothing to lose, except a few mil in R+D, against billions in balance of trade, will be enough to test this concept properly. Should one succeed, I think that it will be another Sputnik moment.

[Typhoon]

IEEE | Nuclear Reactor Renaissance

Nuclear reactor design is poised for a desperately needed revival. Here are seven contenders

The article was written in 2010. I would argue that a rational post-Fukushima Daiichi response would have been to scale up research into new safer reactor design.

[Typhoon]

The thorium nuclear fuel cycle certainly has it's supporters [including myself], however, here's a skeptical view:

IEEE | Is Thorium the Nuclear Fuel of the Future?

[crashtech]

IEEE | Nuclear Reactor Renaissance

Nuclear reactor design is poised for a desperately needed revival. Here are seven contenders

The article was written in 2010. I would argue that a rational post-Fukushima Daiichi response would have been to scale up research into new safer reactor design.

Absolutely. Even the most advanced PWR designs are not "walk-away safe," the spent fuel pool being particularly problematic, in my view. There are still areas of the US and the world remote enough to test new designs without fear of harming the population.

By the way, don't both of your links point to the same article?

[Typhoon]

. . .

By the way, don't both of your links point to the same article?

Thanks for pointing this out. Now fixed.

[crashtech]

The Pebble Bed Reactor has been my favorite for a while, because correct implementations are truly "walk-away safe":

When the nuclear fuel increases in temperature, the rapid motion of the atoms in the fuel causes an effect known as Doppler broadening. The fuel then sees a wider range of relative neutron speeds. Uranium-238, which forms the bulk of the uranium in the reactor, is much more likely to absorb fast or epithermal neutrons at higher temperatures. This reduces the number of neutrons available to cause fission, and reduces the power of the reactor. Doppler broadening therefore creates a negative feedback because as fuel temperature increases, reactor power decreases. All reactors have reactivity feedback mechanisms, but the pebble bed reactor is designed so that this effect is very strong and does not depend on any kind of machinery or moving parts. Because of this, its passive cooling, and because the pebble bed reactor is designed for higher temperatures, the pebble bed reactor can passively reduce to a safe power level in an accident scenario. This is the main passive safety feature of the pebble bed reactor, and it makes the pebble bed design (as well as other very high temperature reactors) unique from conventional light water reactors which require active safety controls.

The reactor is cooled by an inert, fireproof gas, so it cannot have a steam explosion as a light-water reactor can. The coolant has no phase transitions—it starts as a gas and remains a gas. Similarly, the moderator is solid carbon; it does not act as a coolant, move, or have phase transitions (i.e., between liquid and gas) as the light water in conventional reactors does.

A pebble-bed reactor thus can have all of its supporting machinery fail, and the reactor will not crack, melt, explode or spew hazardous wastes. It simply goes up to a designed "idle" temperature, and stays there. In that state, the reactor vessel radiates heat, but the vessel and fuel spheres remain intact and undamaged. The machinery can be repaired or the fuel can be removed. These safety features were tested (and filmed) with the German AVR reactor.[6] All the control rods were removed, and the coolant flow was halted. Afterward, the fuel balls were sampled and examined for damage and there was none.

[Azrael]

What do y'all think about the Energy Multiplier Module?

If they can actually pull it off, it will be pretty much an off the shelf design, making it cheaper than a built-on-site reactor, and it will consume mainly nuclear waste.

[Milo]

What do y'all think about the Energy Multiplier Module?

If they can actually pull it off, it will be pretty much an off the shelf design, making it cheaper than a built-on-site reactor, and it will consume mainly nuclear waste.

One of the known advantages of the Thorium reactor is that they will burn atomic waste down to a puny fraction of its starting mass.

As I understand it, the difference with Thorium is that because you don't have to run it at critical, there's simply no chance of a meltdown, unlike Uranium.

[Azrael]

What do y'all think about the Energy Multiplier Module?

If they can actually pull it off, it will be pretty much an off the shelf design, making it cheaper than a built-on-site reactor, and it will consume mainly nuclear waste.

One of the known advantages of the Thorium reactor is that they will burn atomic waste down to a puny fraction of its starting mass.

As I understand it, the difference with Thorium is that because you don't have to run it at critical, there's simply no chance of a meltdown, unlike Uranium.

That's what I've heard, too. It requires a neutron source, such as an accelerator, to run, so to stop the reactions, one just turns off the neutron source.

[Typhoon]

Two new nuclear reactors approved in US

Physics Today: Today the US Nuclear Regulatory Commission voted in favor of granting a construction license for two nuclear reactors to be built in Georgia.

As reported in the New York Times yesterday, the license will be the first to be issued since the Three Mile Island accident in 1978.

In anticipation, the Southern Company had already invested hundreds of millions of dollars in the project. Although natural gas prices have gone down in the US and no tax has yet been imposed on carbon emissions, proponents had pointed out that market and regulatory factors can change.

Antinuclear groups, such as the Southern Alliance for Clean Energy, tried to sue to block the license because of the risks involved, including potential cost overruns, regulatory problems, and radioactive waste management issues.

The reactor design, Westinghouse's AP1000, is new. Once built, the reactors are supposed to be able to withstand earthquakes, plane crashes, and electricity outages and be less vulnerable to operator error.

[Westinghouse was acquired by Toshiba in 2006]

[crashtech]

I'm not sure if it's fair to call the AP1000 a "new" design. It's a refinement, sure, but it's still basically a PWR. What to you think of the design, Typhoon, is it significantly safer, in your view? Do you think AP1000s would have fared better than the BWRs at Fukushima Daiichi?

[Typhoon]

I'm not sure if it's fair to call the AP1000 a "new" design. It's a refinement, sure, but it's still basically a PWR.

You're correct to note that design is evolutionary rather than revolutionary: Gen III

WH AP1000

What to you think of the design, Typhoon, is it significantly safer, in your view? Do you think AP1000s would have fared better than the BWRs at Fukushima Daiichi?

Hard to speculate. From what I recall the major problem at Fukushima Daiichi was the loss of both primary and secondary backup power for cooling due to the tsunami, so it's not clear that a more modern PWR would have fared better. Making the secondary backup power both tsunami and earthquake proof is key.

PWRs are in some sense an accident of history - commercialization of a design best suited for nuclear material production for weapons and powering nuclear submarines.

[Milo]

CANDUs are still the ones to beat guys!

[Typhoon]

CANDUs are still the ones to beat guys!

Why has Canada not actively pursued the thorium + CANDU option?

[Milo]

CANDUs are still the ones to beat guys!

Why has Canada not actively pursued the thorium + CANDU option?

We've been caught in a dilemma up here for decades.

Our right wing does not want to initiate any projects that would show up the American defense establishment; they have instructions to run a well-behaved branch office! Meanwhile, out left wing wants anything nuclear to go away. The upshot is, that it's a miracle that we even have a program at this point.

However, to be fair, I'm told that only India has built a reactor capable of testing different fuels. Yes, apparently everyone else just decides in advance what will work, based on data decades old, and then runs a huge reactor. India has a reactor where small amounts of fuel can be burned in short runs, so that they can... see what works best! This entire industry runs in a very strange way if you ask me.

[Typhoon]

CANDUs are still the ones to beat guys!

Why has Canada not actively pursued the thorium + CANDU option?

We've been caught in a dilemma up here for decades.

Our right wing does not want to initiate any projects that would show up the American defense establishment; they have instructions to run a well-behaved branch office! Meanwhile, out left wing wants anything nuclear to go away. The upshot is, that it's a miracle that we even have a program at this point.

However, to be fair, I'm told that only India has built a reactor capable of testing different fuels. Yes, apparently everyone else just decides in advance what will work, based on data decades old, and then runs a huge reactor. India has a reactor where small amounts of fuel can be burned in short runs, so that they can... see what works best! This entire industry runs in a very strange way if you ask me.

Unfortunate. Canada strikes me as uniquely positioned to generate virtually all of it's electric power through some combination of nuclear and hydro.

[Typhoon]

Science | Reactor-Accelerator Hybrid Achieves Successful Test Run

A European research team took an important step this week toward proving that an unusual combination of a nuclear reactor and a particle accelerator could be used to eliminate highly radioactive and long-lived nuclear waste produced in conventional nuclear reactors. In Paris yesterday, researchers from the Belgian Nuclear Research Centre (SCK-CEN) in Mol, the French National Research Council (CNRS), and France's Atomic Energy Commission (CEA) reported that they had successfully operated a research reactor called Guinevere by boosting its nuclear reactions with an externally produced beam of neutrons.

Such a set-up is known as an accelerator-driven system (ADS). The reactor in an ADS contains too little fissile material in its core to sustain a nuclear chain reaction. The shortage of material means there isn't enough neutrons. To make the reactor run, extra neutrons must be supplied from another source, such as a proton beam hitting a heavy metal target. That knocks out neutrons in a process called spallation.

The concept of an ADS is almost as old as nuclear power itself: American physicist Ernest O. Lawrence, the inventor of the cyclotron accelerator, suggested the use of particle beams in conjunction with a reactor during the 1950s. The idea gained more ground in the 1980s when Nobel-winning particle physicist Carlo Rubbia proposed building an ADS to generate electricity, which he dubbed the energy amplifier. Since then, most research has focused on using an ADS to transmute high-level nuclear waste into less harmful material. The first working ADS was demonstrated by researchers at Kyoto University in Japan in 2009.

[crashtech]

I believe France has a problem with small amounts of high-level waste that get left over from their closed cycle reprocessing program. A reactor that could "burn" these stubborn and highly radioactive materials would be a great boon to their program.

[Milo]

Thoirum LFTR reactors can burn nuclear waste down to about 1% of its mass, this is well established.

[Azrael]

Thoirum LFTR reactors can burn nuclear waste down to about 1% of its mass, this is well established.

Would the Energy Multiplier Module [see above] also work? I think that it was designed to squeeze remaining energy out of nuclear waste.

[Milo]

Thoirum LFTR reactors can burn nuclear waste down to about 1% of its mass, this is well established.

Would the Energy Multiplier Module [see above] also work? I think that it was designed to squeeze remaining energy out of nuclear waste.

Work I'm sure it would but the LFTR would run a lot cooler and be no bigger, plus the design has been tested and no major problems found.

The biggest problem with selling people on the LFTR is everyone assumes that something that works that well could not have been discovered and then shelved for some 40 years, so they think that it must have a fatal flaw.

[Typhoon]

Thoirum LFTR reactors can burn nuclear waste down to about 1% of its mass, this is well established.

Would the Energy Multiplier Module [see above] also work? I think that it was designed to squeeze remaining energy out of nuclear waste.

Work I'm sure it would but the LFTR would run a lot cooler and be no bigger, plus the design has been tested and no major problems found.

The biggest problem with selling people on the LFTR is everyone assumes that something that works that well could not have been discovered and then shelved for some 40 years, so they think that it must have a fatal flaw.

Not unlike the Aqueous homogeneous reactor. Safe and simple almost to the point of being surreal.