ThorCon Power(thorconpower.com)
thorconpower.com
ThorCon Power
http://thorconpower.com/
94 comments
They can have their own problems. The THTR-300 for instance is one of the few commercial HTGR we had. They had several operational problems like water leaking into the primary circuit (which could lead to hydrogen and oxygen buildups at that temperature). The decommissioning currently is a huge mess. Sadly the English wikipedia doesn't have as much information as the German one about it.
People have been trying for twenty years to find $300 million in government funding to create a new reference design of a modern thorium reactor. TVA's old reactor which ran until the seventies was based on forties research.
But the past three presidents have not made it a national priority. China and India have funded research and so has one private individual, Bill Gates.
But the past three presidents have not made it a national priority. China and India have funded research and so has one private individual, Bill Gates.
It just vexes me that thorium research is not a national priority. How can a technology that, by many estimates, has at least a 50% chance of being a viable replacement of all energy needs over the next 1000 years not be worthy of the US investment? We lose hundreds of billions of dollars per year in oil imports. Why is that not worth avoiding?
It's because nuclear reactors, of any kind, are politically untenable at the moment. Especially unproven designs. Nobody's going to allow one to be built in their back yard, no matter how promising the technology.
I'm not familiar with Thorium reactors at all, so forgive me for asking: how much long-lived nuclear waste do they produce? Because we have no viable way to do with that.
They use about 1/200th amount of fuel compared to current uranium reactors, so the amount of total waste is small.
About 1 tonne thorium per one gigawatt-year.
And the wastes they produce have a far smaller portion of long lived isotopes, because the reactor controls very well what substances receive neutrons.
Here's the best image comparison I could find. http://4.bp.blogspot.com/-mAg4r-09gm0/TdZeWHzJWEI/AAAAAAAAAh... http://4.bp.blogspot.com/-mAg4r-09gm0/TdZeWHzJWEI/AAAAAAAAAh...
About 1 tonne thorium per one gigawatt-year.
And the wastes they produce have a far smaller portion of long lived isotopes, because the reactor controls very well what substances receive neutrons.
Here's the best image comparison I could find. http://4.bp.blogspot.com/-mAg4r-09gm0/TdZeWHzJWEI/AAAAAAAAAh... http://4.bp.blogspot.com/-mAg4r-09gm0/TdZeWHzJWEI/AAAAAAAAAh...
> I'm not familiar with Thorium reactors at all, so forgive me for asking: how much long-lived nuclear waste do they produce?
Almost none of the 250,000 year stuff. Almost entirely the 300 year stuff. Also, about 1/4 the total mass of all waste product.
Additionally, according to their documentation, the 250,000 year stuff is ultimately cycled back into the reactor to be destroyed. Most long-lived nuclear waste is fissionable, so you can just use it as more fuel, given that you can remove the fission products from the fuel easily.
Almost none of the 250,000 year stuff. Almost entirely the 300 year stuff. Also, about 1/4 the total mass of all waste product.
Additionally, according to their documentation, the 250,000 year stuff is ultimately cycled back into the reactor to be destroyed. Most long-lived nuclear waste is fissionable, so you can just use it as more fuel, given that you can remove the fission products from the fuel easily.
[deleted]
The idea is that not only do they not produce long-lived waste, but some designs can even recycle the 'spent' fuel from conventional reactors.
Is this in models -- molten salt? -- where the fuel circulates in liquid form?
Norway has also put a bit of money into thorium reactor R&D, with a small modern experimental reactor currently operating on a 5-year trial: http://www.extremetech.com/extreme/160131-thorium-nuclear-re...
In fact it is an old test reactor from the 1950ies.
What they have done, though, which is still very cool, is use thorium instead of uranium in a conventional nuclear reactor.
What they have done, though, which is still very cool, is use thorium instead of uranium in a conventional nuclear reactor.
Gates isn't working on Thorium; the TWR is a uranium / plutonium reactor.
impressive - http://en.wikipedia.org/wiki/Pebble-bed_reactor#AVR
" There exists currently no dismantling method for the AVR vessel, but it is planned to develop some procedure during the next 60 years and to start with vessel dismantling at the end of the century."
German methodical planning :)
" There exists currently no dismantling method for the AVR vessel, but it is planned to develop some procedure during the next 60 years and to start with vessel dismantling at the end of the century."
German methodical planning :)
As long as it is relatively secure, monitoring it and otherwise keeping away is probably an ok strategy. At least the half-lifes are only in the decades if I remember correctly.
That amazing piece of technology is in my birth town (or city, if you're generous).
While I never actively followed the plant's history, I do remember quite a bit of resistance, reports about potential 'leaks' and talks about it being not reliable enough.
While I never actively followed the plant's history, I do remember quite a bit of resistance, reports about potential 'leaks' and talks about it being not reliable enough.
Never been a fan of HTGRs; the problem with LWRs is pressure, and what happens if you get to much of it or have a material failure. HTGRs have the same issue (though, not the potential for thermocatalytic degredation of the fuel elements).
So they've finally managed to solve the little problem of the extremely high temperature AND highly corrosive nature of this fuel?
The high temperature limits the materials we can choose from. We've elected to stick with known materials (stainless steel) for the first generation to keep our schedule short.
As someone noted below highly corrosive depends on the material you are in. The fuel salt is actually pretty modestly corrosive as long as the chemistry is kept right. Specifically, we have to keep the fuel salt reducing - we don't want any free fluorine running around. We keep a balance between UF3 and UF4 (roughly 99% UF4). It's like keeping the chemical balance in your swimming pool. Under those conditions the vessel will last a very long time indeed (>60 years). But it takes a long time to prove this and we have to swap out the graphite anyway so we swap out all critical components every four years. They get disassembled, cleaned, and normally put back into service with a new graphite load. This is kindof like your laser printer cartridge.
Stainless steel. Could you go into more depth about who's making your pipes and fittings? What surface treatments will you be using, etc? Will you be putting a cooling jacket, insulation, or anything over the pipes? Very interesting in the metallurgy you're using since it appears to be the BIGGEST problem of the MSRE at Oakridge.
Also, what happened to that experimental reactor? Didn't Obama send it to Norway or something?
Also, what happened to that experimental reactor? Didn't Obama send it to Norway or something?
The challenge with metallurgy for MSRE was two fold. First was the neutron interaction with nickle forming helium that migrated to the grain boundaries. We avoid this problem altogether by having a single fluid design with a protective shield of B4C absorbing neutrons before they hit the wall.
The second problem was with tellerium penetrating the Hastalloy and weakening it at the grain boundaries. This isn't a problem with stainless steel.
The stainless steel planned is SS316 which is available from multiple sources.
The primary loop does not have insulation surrounding it but it does have a 1m thick graphite reflector to bounce most of the neutrons back to the core then a layer of B4C to absorb the rest before they get to the vessel.
The MSRE was shutdown decades ago and recently had its fuel salt removed. The vessel and piping are still in Oak Ridge inside its concrete silo.
The second problem was with tellerium penetrating the Hastalloy and weakening it at the grain boundaries. This isn't a problem with stainless steel.
The stainless steel planned is SS316 which is available from multiple sources.
The primary loop does not have insulation surrounding it but it does have a 1m thick graphite reflector to bounce most of the neutrons back to the core then a layer of B4C to absorb the rest before they get to the vessel.
The MSRE was shutdown decades ago and recently had its fuel salt removed. The vessel and piping are still in Oak Ridge inside its concrete silo.
Great, grain boundaries are really what it gets down to.
I only have two things to say: 1.) Good luck testing and gathering data on these ideas. You'll need it. 2.) Are you hiring mechanical engineers?
I only have two things to say: 1.) Good luck testing and gathering data on these ideas. You'll need it. 2.) Are you hiring mechanical engineers?
What happens when something goes very wrong and corrosion happens? Does the fuel leak into groundwater?
The primary loop (that contains all the fuel salt and fission products) is inside a can so if we get a leak in the primary loop the salt will be contained inside the can. The can drains to the fuel dump tank (FDT). Both the can and FDT get passively cooled by the membrane and all entrance pipes come in from above so there is no weakness at the bottom.
These in turn are inside a silo, which is inside the silo hall. All total there are four barriers to break through before we get radioactive release.
Further, the fission products are combined with fluoride upon forming (when you fission UF4 the uranium is split into two fission products and the F4 is available for recombining with the fission products). Most of the fission products like to stay in the salt so even if the salt gets spilled the fission products won't wander farther than the salt spill.
These in turn are inside a silo, which is inside the silo hall. All total there are four barriers to break through before we get radioactive release.
Further, the fission products are combined with fluoride upon forming (when you fission UF4 the uranium is split into two fission products and the F4 is available for recombining with the fission products). Most of the fission products like to stay in the salt so even if the salt gets spilled the fission products won't wander farther than the salt spill.
And what will happen to the solidified salt spill? Could it be safely cleaned up or would it be too radioactive to approach?
It will be rather intensely radioactive. A person cannot approach it. A cleanup like this would have be done robotically. If the spill is contained in the can then the whole can is designed to be sealed and shipped back to the can recycling center where there are facilities for cleaning up the can. The main point though is that the spill is contained within the building and does not spread to the environment. A worst case accident becomes an economic loss of the reactor rather than a mass evacuation.
When it comes to corrosion, the question is always "corrosive in what?" A couple years ago I looked through the Oak Ridge documents on MSRs, and they appeared to be pretty confident that the alloys they were using were sufficiently durable.
It looks like this prototype is based on the Oak Ridge MSR experiment, which ran successfully for years didn't it?
Yes it is based on their work. MSRE was a successful experiment that gathered a lot of data. MSBR and DMSR were follow paper designs based on MSRE. We've combined elements of each. A major difference though is that we are not trying to be a breeder yet. Our first priority is to be very safe and lower cost than coal as soon as possible. We'll leave breeding and absolute minimal waste production for a second generation.
Nope.
Molten salt corrodes stainless at a rate of 0.025 mm / year. The solution: make the walls thicker, change out and inspect the primary vessel and plumbing every 4 years; you get 40 years per millimeter.
Molten salt corrodes stainless at a rate of 0.025 mm / year. The solution: make the walls thicker, change out and inspect the primary vessel and plumbing every 4 years; you get 40 years per millimeter.
I think their solution to that is to replace all of the parts every 4 years.
This makes me think I do not understand what "walkaway safe" means.
This means that in the event of a problem the reactor both shuts down and passively disposes of the decay heat so that it has not chance of going critical (starting up) again (which was a risk at Fukishima without active cooling).
At that point you can just let it sit there "forever" if you want. Not that you would of course, you'd want to clean it up.
At that point you can just let it sit there "forever" if you want. Not that you would of course, you'd want to clean it up.
The design has two passive cooling systems. The first uses natural circulation through the heat exchangers to the normal primary cold sink. The second uses radiative heat to the membrane to a pond intended specifically for decay heat. Either one alone is sufficient - so if something (like a tsunami) takes out the primary cold sink we can still cool the core. If despite this the core overheats then it drains to the fuel drain tank. There we have passive cooling using the membrane.
If the drain between the core and the drain tank fails AND the both other passive cooling methods fail to keep the core cool enough then yes eventually the core vessel will fail. In that case, the fuel escapes the first containment (the primary loop) into the can. The can drains to the fuel drain tank so we still provide cooling.
If the drain between the core and the drain tank fails AND the both other passive cooling methods fail to keep the core cool enough then yes eventually the core vessel will fail. In that case, the fuel escapes the first containment (the primary loop) into the can. The can drains to the fuel drain tank so we still provide cooling.
The overall concept is good, but there could be things that go wrong in the real world. How fast the heat ramps up vs the failsafe plug in the vessel melting, or the chance of some material failure shedding debris which could potentially plug the drain path.
Actually if you read the Oakridge reports those cases are considered. For reference this reactor would have both survived and shut down cleanly in both the Chernobyl (over driving the reaction) and Fukishima (30m tsunmai + 9+ earthquake) situations.
You don't have to handle the decay heat with active cooling after stopping fission. You can simply "walkaway safe". They're using physics and engineering design to replace failsafe systems.
"Walkaway safe" means that in an emergency/failure situation, it transitions from "working reactor" to "broken reactor" without threatening lives and property with danger (at least, not threatening once you've exited the reactor complex proper -- you might in fact need to walk away, especially if there are fires and things that caused the problem).
The alternative is a Fukushima-style transition from "working reactor" to "unapproachable death trap generating clouds of hydrogen gas which can explode the containment dome, sending toxic radioactive smoke from uranium fires into the atmosphere (while other material leaches into the ocean via the water table)". Even Fukishima's spent-fuel cooling ponds required water be added for for weeks and weeks on end.
If you'd like it to keep the reactor working while walking away from it, that's another matter which is keyworded something like "unattended operation" not "walk-away safe".
The alternative is a Fukushima-style transition from "working reactor" to "unapproachable death trap generating clouds of hydrogen gas which can explode the containment dome, sending toxic radioactive smoke from uranium fires into the atmosphere (while other material leaches into the ocean via the water table)". Even Fukishima's spent-fuel cooling ponds required water be added for for weeks and weeks on end.
If you'd like it to keep the reactor working while walking away from it, that's another matter which is keyworded something like "unattended operation" not "walk-away safe".
If you've got your thorium spread out and not reacting it should no longer be high temperature well before the 4 years are up.
Molten salt is way less corrosive than water.
Very black and white answer there, which is odd as it is a very relative question. Salt is actually incredibly corrosive to a lot of things, as is water, but what materials are we asking how corrosive they are against?
I'm assuming the grandfather post means against metals (stainless steel specifically).
It seems that thorium reactors produce less nuclear waste than uranium reactors: https://en.wikipedia.org/wiki/Thorium_fuel_cycle#Fission_pro.... Could someone with more knowledge on the subject give a rough estimate of the amount of waste we would be talking about?
There are many different thorium designs based on different objectives. The original designs assumed that we would run out of uranium so the primary objective was breeding. It is clear now that we have much more uranium than they thought.
We should start with an understanding of how much waste is there currently from today's reactors. Roughly one coke can would hold all the waste generated from one person's electricity (European standards roughly 1kW) for a lifetime. We can reduce the volume of waste readily by removing the uranium and re-enriching it. This can be done with virtually all reactors including todays reactors. This will remove 90% of the waste volume but does nothing to reduce the hazards of the waste.
We can remove the elements that are heavier than uranium (transuranics or TRUs). This is the long term hazard. This material can be recycled into a reactor to be fissioned (destroyed forever not simply buried). This can be done to a very limited extent in some of today's reactors. But either IFR or molten salt reactors would really be the appropriate way to eliminate the long term hazards of nuclear waste. Such a process will be limited by our ability to separate the TRUs from the fission products. We expect to achieve around 99% separation so to reduce the long term hazard 100 fold.
The near term hazard comes from the fission products. These will decay in a reasonable time. Every 30 years the radioactivity will decay by half. So by 300 years you are back to roughly background radiation. 300 years is short enough we know how to build containers to last that long.
We should start with an understanding of how much waste is there currently from today's reactors. Roughly one coke can would hold all the waste generated from one person's electricity (European standards roughly 1kW) for a lifetime. We can reduce the volume of waste readily by removing the uranium and re-enriching it. This can be done with virtually all reactors including todays reactors. This will remove 90% of the waste volume but does nothing to reduce the hazards of the waste.
We can remove the elements that are heavier than uranium (transuranics or TRUs). This is the long term hazard. This material can be recycled into a reactor to be fissioned (destroyed forever not simply buried). This can be done to a very limited extent in some of today's reactors. But either IFR or molten salt reactors would really be the appropriate way to eliminate the long term hazards of nuclear waste. Such a process will be limited by our ability to separate the TRUs from the fission products. We expect to achieve around 99% separation so to reduce the long term hazard 100 fold.
The near term hazard comes from the fission products. These will decay in a reasonable time. Every 30 years the radioactivity will decay by half. So by 300 years you are back to roughly background radiation. 300 years is short enough we know how to build containers to last that long.
Uranium reactors use something like 2% of the total energy available in the uranium. Molten-salt-reactors use something like 98% of the available energy. Additionally, the 2% that is waste contain extremely rare derivatives that can be used as cancer "smartbombs", metals pivotal to deep space NASA missions, etc.
This has a pretty good overview: https://www.youtube.com/watch?v=P9M__yYbsZ4
This has a pretty good overview: https://www.youtube.com/watch?v=P9M__yYbsZ4
A MSR breeder can potentially burn 98% of the available energy; ThorCon is a converter, but not a breeder. From what I can glean from their website and documentation, it looks like they get about 20% burnup.
India has very rich monzanite deposits. If the claims published are real, India has found one awesome solution to address the present energy crisis.
Problem for them is the time and non-Thorium resources needed to enrich the thorium. They're set for 50 years from now. Not today.
The design choices have been specifically made to allow for a short development cycle and rapid deployment. There is no need to enrich thorium as virtually all thorium in the world is Th232.
Looks like an expert crew and quite thought through design. Now all it needs is an Elon Musk to push it into existence in record time.
Are they already in production, is it being sold, do they need funding, are they going to do a Kickstarter? (half joking, I can imagine it happening) This tech sounds cool, but the site doesn't say anything about implementations.
I think it's mostly just designed to raise awareness. There's no "Get Involved" link, but I'm not sure how your average citizen gets involved with nuclear tech in general...
No we are not in production. Yes we do need funding but this is not on a kickstarter scale though. This will require hundreds of millions of dollars to become real so we do need to involve a large corporation or some wealthy folks.
> ThorCon can produce reliable, carbon free, electricity at between 3 and 5 cents per kWh depending on scale.
How does this compare to traditional nuclear power and other forms of power generation?
How does this compare to traditional nuclear power and other forms of power generation?
We expect to be around 1/8th the capital cost for the reactor itself. We plan to use off-the-shelf turbines&generators marketed for coal so those costs are pretty well known. You still have to add in the switch yard and transmission lines which we won't provide any advantage in. Overall, though we expect to come in below the cost of coal and natural gas including the cost of capital. One can always use the regulatory system to drive up costs like has been done in the US.
Hey Lars. Thanks for working on this! I used to work at Westinghouse and had a very similar concept of using thorium as the primary system and hooking it up to existing coal secondary systems. I really hope you find a way to easily get the material for the initial core.
Instead of shipping containers, my thought was on using the existing rail systems, although that's very US centric.
What's the next step? What can the HN community do for you?
Instead of shipping containers, my thought was on using the existing rail systems, although that's very US centric.
What's the next step? What can the HN community do for you?
[deleted]
Supposedly much cheaper than the coal one[1]. Although I don't know how representative this 1000 MWe coal plant is.
[1] http://thorconpower.com/costing/bottom-line
[1] http://thorconpower.com/costing/bottom-line
I pay around 7.5 cents/kWH for coal-based power. (+ $30~40/month in various fees and taxes.)
If one could sell one reactor's worth, a gigawatt, of continuous power at that price, it'd be 1,8 million dollars per day and over 500 million dollars per year. Over 30 years it'd be 15 billion dollars.
You have to put up quite a few windmills and solar panels to get to such numbers.
On the other hand, the Olkiluoto three 1,6 GW nuclear plant has taken more than a decade and countless billions and still isn't ready.
You have to put up quite a few windmills and solar panels to get to such numbers.
On the other hand, the Olkiluoto three 1,6 GW nuclear plant has taken more than a decade and countless billions and still isn't ready.
I mean this in the nicest possible way, but you guys need to redo yr site - a lot of the design cues make it look like a one-man fringe project which (assuming that's not the case here) is unfortunate
edit: more specifically, it's not about making it look more expensive/complex/modern but moving away from the specific aesthetic it has right now
edit: more specifically, it's not about making it look more expensive/complex/modern but moving away from the specific aesthetic it has right now
OK, so here is an idea for disposing nuclear waste that might sound outlandish: with the current progress in putting stuff in space, couldn't be compactify all that waste and throw it at the sun?
Nuclear waste is extremely dense and therefore extremely heavy. It would cost an incredible amount of money to launch it into space, let alone the sun. The corollary is it's also really valuable since it still contains an incredible amount of energy, our current reactors only burn 5% of it where as future reactors will be able to burn all of it. An analogy I often use is we're burning just the kindling and our 'waste' is the hard oak that's harder to burn.
That question is asked and answered here:
http://www.reddit.com/r/askscience/comments/2r43nl/why_dont_...
http://www.reddit.com/r/askscience/comments/2r43nl/why_dont_...
Any rocket that could deliver nuclear waste to the sun would use an awful lot of fuel, given the density of the waste, and would be a very big problem if there was a failure shortly after launch.
Also, anything that could deliver radioactive waste to the sun could deliver it to a major city just as easily.
Also, anything that could deliver radioactive waste to the sun could deliver it to a major city just as easily.
The risk of fallout and the fuel costs are too significant.
Easier to build a modern nuclear reactor that can use nuclear waste for fuel- there are projects in the works to do just this.
What do you do when the rocket explodes on launch?
Is there an ELI5 version?
Its a nuclear generator factory.
It uses molten salt as the catalyst for nuclear reaction, using thorium as the fuel.
The molten salt allows passive safety measures, significantly reducing the negative effects of a meltdown. It also significantly reduces the size of the reactors housing.
The use of thorium allows for significantly cheaper nuclear fuel, which happens to be very difficult to convert to weapon-grade nuclear fuel. By very difficult, I mean very difficult for a nation state, let alone a small group of bad actors.
It uses molten salt as the catalyst for nuclear reaction, using thorium as the fuel.
The molten salt allows passive safety measures, significantly reducing the negative effects of a meltdown. It also significantly reduces the size of the reactors housing.
The use of thorium allows for significantly cheaper nuclear fuel, which happens to be very difficult to convert to weapon-grade nuclear fuel. By very difficult, I mean very difficult for a nation state, let alone a small group of bad actors.
In spite of the name "ThorCon", there's no mention of thorium on the front page.
http://thorconpower.com/features/clean says:
> And ThorCon obtains about 25% of its power from easily mined thorium which requires no enrichment.
http://thorconpower.com/design/thorcon-can says the "fuelsalt" is "a mixture of sodium, beryllium, uranium and thorium fluorides called nabe".
http://thorconpower.com/features/clean says:
> And ThorCon obtains about 25% of its power from easily mined thorium which requires no enrichment.
http://thorconpower.com/design/thorcon-can says the "fuelsalt" is "a mixture of sodium, beryllium, uranium and thorium fluorides called nabe".
Interesting, I wonder if fuelsalt is more efficient or cheaper. I do know that thorium is tightly controlled in the US.
I'm pretty sure uranium is tightly controlled too.
So basically, they are better on every possible front, and the technology has existed for a while?
Yet, LWR is still the dominant design. So, what's the catch? There's clearly something preferable about Uranium LWR that causes their dominance, no?
Yet, LWR is still the dominant design. So, what's the catch? There's clearly something preferable about Uranium LWR that causes their dominance, no?
When nuclear research was first being developed, it was for the specific purpose of building the bomb. When the war ended, and the industry switched to civilian applications, they decided to go with Uranium because they had already worked out many of the issues.
Still, the US Airforce wanted a nuclear-powered bomber shortly after the Navy showed their nuclear sub and before ICBM's deprecated "end-of-days" long-range bombers. A water-contained reactor wouldn't work in an airplane, so they funded the development of the MSR (molten-salt-reactor).
Unfortunately, when they shuddered the project after the implementation of practical ICBMs, industry politics discredited MSR's in favour of the reactor-types we have now.
After fukushima, a grassroots campaign has been undertaken to resume research of MSR's as a replacement of fossil fuels for scalable carbon-free energy creation. If you are interested, you can get a great overview here: https://www.youtube.com/watch?v=P9M__yYbsZ4
Still, the US Airforce wanted a nuclear-powered bomber shortly after the Navy showed their nuclear sub and before ICBM's deprecated "end-of-days" long-range bombers. A water-contained reactor wouldn't work in an airplane, so they funded the development of the MSR (molten-salt-reactor).
Unfortunately, when they shuddered the project after the implementation of practical ICBMs, industry politics discredited MSR's in favour of the reactor-types we have now.
After fukushima, a grassroots campaign has been undertaken to resume research of MSR's as a replacement of fossil fuels for scalable carbon-free energy creation. If you are interested, you can get a great overview here: https://www.youtube.com/watch?v=P9M__yYbsZ4
> Unfortunately, when they shuddered the project after the implementation of practical ICBMs, industry politics discredited MSR's in favour of the reactor-types we have now.
So essentially what you're seeing is the result of decades of regulatory capture of the NRC by the nuclear industry.
So essentially what you're seeing is the result of decades of regulatory capture of the NRC by the nuclear industry.
I think the missing factor is that there are massive regulatory hurdles in the way of testing new designs, no?
... well, yeah: placing massive hurdles in the way of potential competitors and their technologies is about half of the premise of regulatory capture...
It's amazing how the state of things may look like a local maximum depending on the root of the research path.
In light-water reactors, the highly radioactive part of the system is very simple. It's a core of metal fuel rods and support structure, some control rods, and water. All the plumbing complexity is external, and it's on water, which isn't hard to handle.
Most of the alternative reactor designs have more going on in the radioactive part of the system, or more difficult working fluids. This usually leads to trouble. Sodium-cooled reactors have sodium fires. Helium-cooled reactors have helium leaks. Pebble bed reactors have pebble jams. (The one in Germany is so jammed it can't be decommissioned.) Molten salt reactors have to pump radioactive molten salt around and run it through a chemical processing plant. In some designs that salt is a fluorine compound. Now you have all the headaches of operating a radioactive chemical plant.
Most power utilities don't want to operate a radioactive chemical plant.
Most of the alternative reactor designs have more going on in the radioactive part of the system, or more difficult working fluids. This usually leads to trouble. Sodium-cooled reactors have sodium fires. Helium-cooled reactors have helium leaks. Pebble bed reactors have pebble jams. (The one in Germany is so jammed it can't be decommissioned.) Molten salt reactors have to pump radioactive molten salt around and run it through a chemical processing plant. In some designs that salt is a fluorine compound. Now you have all the headaches of operating a radioactive chemical plant.
Most power utilities don't want to operate a radioactive chemical plant.
I wondered what had happened to pebble beds. http://en.wikipedia.org/wiki/AVR_reactor
Most power utilities don't want to operate a radioactive chemical plant
This is a brilliant phrase, thankyou.
Most power utilities don't want to operate a radioactive chemical plant
This is a brilliant phrase, thankyou.
I have little more than a layman's understanding of the nuclear power landscape (I've read a decent bit and watched several talks, but that's about where it ends), but it seems to me that there are at least two reasons: 1) LWR reactors have been built for a long time, so they're very well understood (known risks are better than unknown risks) and the processes are already in place to bring them up. 2) Even though they're dominant, very few LWRs are built. There simply aren't many reactors being built of any kind, so it's unsurprising that the most common type (traditionally) is what we keep building.
> LWR reactors have been built for a long time, so they're very well understood (known risks are better than unknown risks)
After Fukushima, I don't think most people would agree the risks are well understood, at least as reflected in the actions of the nuclear industry and its regulators.
The NRC (and hence most of the world's regulators) uses a "design basis" approach to establish what emergencies reactors should be able to respond to safely without the release of radioactive materials. The design basis is supposed to quantify the known risks.
In 2011 we saw just how inadequate the design basis framework was. It failed to predict risks such as multiple systems failing simultaneously, emergency generators being flooded, the plant being cut off from external help, multiple meltdowns happening simultaneously, valves getting stuck open, and a litany of other things that actually happened, resulting in the level 7 accident we saw.
While the exact set of events that happened at Fukushima Daiichi is unique, similar accidents could happen in the US, or indeed anywhere (e.g. many reactors are downstream from major dams and could theoretically experience catastrophic flooding).
And just as the NRC's computer models deemed Fukushima impossible before the accident, the NRC has largely ignored the recommendations of its own near-term task force in how to improve the regulatory situation in the US after the accident.
It is up to us to demand that the nuclear power industry, which is wielding technology of massive destructive power at the behest of its shareholders, transform itself into the transparent, accountable industry we deserve.
After Fukushima, I don't think most people would agree the risks are well understood, at least as reflected in the actions of the nuclear industry and its regulators.
The NRC (and hence most of the world's regulators) uses a "design basis" approach to establish what emergencies reactors should be able to respond to safely without the release of radioactive materials. The design basis is supposed to quantify the known risks.
In 2011 we saw just how inadequate the design basis framework was. It failed to predict risks such as multiple systems failing simultaneously, emergency generators being flooded, the plant being cut off from external help, multiple meltdowns happening simultaneously, valves getting stuck open, and a litany of other things that actually happened, resulting in the level 7 accident we saw.
While the exact set of events that happened at Fukushima Daiichi is unique, similar accidents could happen in the US, or indeed anywhere (e.g. many reactors are downstream from major dams and could theoretically experience catastrophic flooding).
And just as the NRC's computer models deemed Fukushima impossible before the accident, the NRC has largely ignored the recommendations of its own near-term task force in how to improve the regulatory situation in the US after the accident.
It is up to us to demand that the nuclear power industry, which is wielding technology of massive destructive power at the behest of its shareholders, transform itself into the transparent, accountable industry we deserve.
LWR is what the Navy used, and the civilian designs were just based on that.
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If I'm understanding it correctly, the term "meltdown" doesn't even really apply to this design since the fuel is already liquid.
You are correct- I use the term meltdown to encapsulate an event that causes significant damage to the control of a reactor, such as an earthquake followed by a tsunami.
In such an event, an MSR has a "drain tank" that sits below the reactor. In an emergency, gravity drops the salt into the drain tank, and the nuclear reaction safely comes to a halt- all with zero human intervention.
In such an event, an MSR has a "drain tank" that sits below the reactor. In an emergency, gravity drops the salt into the drain tank, and the nuclear reaction safely comes to a halt- all with zero human intervention.
Perhaps it would be better to use the term 'containment failure'.
I'm surrounded by vehement anti-nuclear types, you know the ones who get arrested for their environmental activism antics. When talking about nuclear technology with them I find it helpful not to utter certain words like 'meltdown', 'weapons', etc etc.
I'm surrounded by vehement anti-nuclear types, you know the ones who get arrested for their environmental activism antics. When talking about nuclear technology with them I find it helpful not to utter certain words like 'meltdown', 'weapons', etc etc.
Is it just me, or did anyone else expect to see plans for a convention based around the Norse god / Marvel character?
I wasn't sure if the link was to some new technology or a cartoon character.
They should call it the "Thorium Brotherhood".
http://en.wikipedia.org/wiki/Very-high-temperature_reactor suggests that gas-cooled reactors tend to be pebble-bed, and that the story gets confused because there's a molten salt version of the pebble-bed reactor as well.
Anyhow, googling on HTGR (High Temperature Gas Reactor) will reveal more.