Wasn't uranium-based nuclear energy supposed to be very cheap, too, and then it turned out it wasn't that cheap? I worry the same will happen with thorium.
Also how much safer is it? Can it be set-up just a few KM outside a city? Is there any dangerous waste to deposit at all?
I do think that if we are to continue research in nuclear energy it should be based on Thorium, rather than uranium, but in the same time, I would much rather have the focus of the energy industry be solar energy right now.
I hope countries in the future are powered 70-80% by solar, and 20-30% by other sources like nuclear energy (at least until we figure out how to store solar energy cheaply for night use), than the other way around. And we can only get there fast if we have the industry's almost complete focus on solar energy, and have them invest billions into researching it and lowering the cost of solar panels.
Power consumption only drops to about 50% of the daytime peak at night[1]. Unless you have somewhere to store that solar, you have to plan on "other sources" producing at least 50%, and more likely significantly more. I consider Utah to be a pretty sunny place, but it is still cloudy nearly a third of the year[2].
Sure, you can couple wind and solar, but that still doesn't help when we get a valley fog inversion for most of January that reduces sunlight to 30% of already short days and no wind is blowing anywhere nearby. Utah doesn't really have the spare water capacity to use it as a potential energy store, either.
The point being that, as great as renewables are, without a way to cheaply store vast amounts of renewable energy or a way to shuffle energy from great distances, it isn't going to work on its own. We need a solid baseline, which, of course, is coal today, but I'd much rather keep looking for better nuclear.
There's a lot of energy in those bonds; I have a great deal of confidence we can find a way to leverage it without all of the nasty side-effect. We just need to get past the knee-jerk reaction of "nuclear is bad" and to a better place of "today's nuclear leaves a lot to be desired, but it doesn't mean tomorrow's will"[3].
3. http://www.quaker.org/fep/CES1.html - You can see that Nuclear is far less deadly than coal, but, when things go wrong, it costs a whole lot more than coal.
Better still, adjust demand to it changes with supply by having electric cars with removable batteries, the batteries being recharged when there is excess power.
> Sure, you can couple wind and solar, but that still doesn't help when we get a valley fog inversion for most of January that reduces sunlight to 30% of already short days and no wind is blowing anywhere nearby.
Utah is connected to the rest of the USA. Is it ever not sunny and not windy everywhere?
CANDU runs on natural uranium so the waste products are actually less radioactive than what we take out of the earth, as well CANDU can burn nuclear waste from light water reactors alleviating the need for Yucca mountain.
Lets look at it's meltdown profile, CANDU reactors need heavy water to function, if you replace the heavy water with light water fission stops, no meltdown. Also before the reactor would ever get to that point the fuel bundles deform, halting meltdown.
CANDU reactors are designed to put less radioactive material back into the earth than came out of it, and when problems occur in a CANDU design it fails safe.
>CANDU runs on natural uranium so the waste products are actually less radioactive than what we take out of the earth, as well CANDU can burn nuclear waste from light water reactors alleviating the need for Yucca mountain.
There is less uranium in the waste, but there will be fission products and trans-uranium elements just like in the fuel of regular reactors. Radioactivity of uranium is hardly a problem, when dealing with spent fuel. In short term (less than 100 years) fission products produce most of the radioactivity. In long term trans-uranium elements are the problem.
>Lets look at it's meltdown profile, CANDU reactors need heavy water to function, if you replace the heavy water with light water fission stops, no meltdown. Also before the reactor would ever get to that point the fuel bundles deform, halting meltdown.
Halting a normal fission chain reaction is hardly a source of accidents in any current nuclear reactor design. Decay heat is produced in the spent nuclear fuel of CANDUs just like in Fukushima or Three Mile Island.
CANDU is an interesting reactor design, but there is none as great alternative as you propose. However, various active and passive safety measures may get you very close. I don't know CANDU design so well, that I could judge those.
Interesting, I thought the large heat sink inherent in the CANDU design essentially ensured that with no human interaction that CANDU reactors would failsafe. My understanding was such that the 'reactor' might be destroyed but the design was such that the failure cascade would not release radioactive materials outside of the containment units.
As I said, I don't know the safety systems of CANDU :)
Large heat sink buys you time to get the cooling working again. Ultimately the heat must be transferred out somehow. In modern reactor designs these systems are usually designed to passively for very long times. With CANDU's it is very likely to be the case too.
In nuclear engineering one must always consider also the chance, that not everything is working as designed (like the destroyed diesel generators and external power sources at Fukushima). PRA (Probabilistic Risk Analysis) is used for that. PRA analysis are used for detecting most vulnerable systems in a nuclear power plant and this information is used to design new safer reactor types and to update the old ones little by little to be still safer. Harsh weather, seismic activity etc. is also considered in these analysis, but sadly in Fukushima even detected vulnerabilities didn't lead to improvements in time.
Even, if everything is done as well as possible, there is still a chance (although with modern designs almost arbitrarily small) that under certain conditions all the safety systems will fail. An ultimate example of such an event, would be a 100 km meteorite smashing the plant to atoms.
We agree on older plants being not as safe as new ones. My original sentence was about things you just can't prepare for (with any reasonable means). After that I just wanted to say, that it is possible to build plane-safe NPP.
Maybe yes, maybe no. Some CANDU negatives I'll chip in though: CANDU is one of the more successful vectors to creating nuclear-armed states; and it's not all that reliable - the uptime of the Bruce reactors is tolerable if you adopt a flexible definition.
Uranium fuels were never deployed because of cost or safety, they were deployed because various militaries funded the technology for use a) producing plutonium for weapons, and b) producing energy for large Navy customers.
Civilian nuclear energy based on the uranium fuel cycle is a spin off from a warfighter's R&D project.
Compare that with the thorium fuel cycle which does not produce weaponizable byproducts.
Generally when talking about how safe a given sort of nuclear power is the most important thing to consider is whether it has a positive void coefficient or not. That is, if the reactor starts to overheat will that make it generate more power or less. In light water reactors, such as pretty much all existing commercial reactors, you need complicated feedback systems to keep the reactor under control. And if those are damaged, as at Fukushima, you're looking at a melt down.
>Generally when talking about how safe a given sort of nuclear power is the most important thing to consider is whether it has a positive void coefficient or not.
The void coefficient is only appropriate, when you are dealing with a criticality accident like in Chernobyl. Criticality accident (fission chain reaction getting out of hand) has never happened in commercially used Western reactors. In fact, in Western countries you can not get a license for a reactor design, which has positive temperature coefficient for power i.e. the fission power must decrease, if temperature increases.
Comments
Wasn't uranium-based nuclear energy supposed to be very cheap, too, and then it turned out it wasn't that cheap? I worry the same will happen with thorium.
Also how much safer is it? Can it be set-up just a few KM outside a city? Is there any dangerous waste to deposit at all?
I do think that if we are to continue research in nuclear energy it should be based on Thorium, rather than uranium, but in the same time, I would much rather have the focus of the energy industry be solar energy right now.
I hope countries in the future are powered 70-80% by solar, and 20-30% by other sources like nuclear energy (at least until we figure out how to store solar energy cheaply for night use), than the other way around. And we can only get there fast if we have the industry's almost complete focus on solar energy, and have them invest billions into researching it and lowering the cost of solar panels.
Power consumption only drops to about 50% of the daytime peak at night[1]. Unless you have somewhere to store that solar, you have to plan on "other sources" producing at least 50%, and more likely significantly more. I consider Utah to be a pretty sunny place, but it is still cloudy nearly a third of the year[2].
Sure, you can couple wind and solar, but that still doesn't help when we get a valley fog inversion for most of January that reduces sunlight to 30% of already short days and no wind is blowing anywhere nearby. Utah doesn't really have the spare water capacity to use it as a potential energy store, either.
The point being that, as great as renewables are, without a way to cheaply store vast amounts of renewable energy or a way to shuffle energy from great distances, it isn't going to work on its own. We need a solid baseline, which, of course, is coal today, but I'd much rather keep looking for better nuclear.
There's a lot of energy in those bonds; I have a great deal of confidence we can find a way to leverage it without all of the nasty side-effect. We just need to get past the knee-jerk reaction of "nuclear is bad" and to a better place of "today's nuclear leaves a lot to be desired, but it doesn't mean tomorrow's will"[3].
1. http://www.mpoweruk.com/electricity_demand.htm
2. http://www.currentresults.com/Weather/Utah/sunshine-by-month...
3. http://www.quaker.org/fep/CES1.html - You can see that Nuclear is far less deadly than coal, but, when things go wrong, it costs a whole lot more than coal.
> Unless you have somewhere to store that solar
You could hollow out a mountain and pump water up and down -- http://en.wikipedia.org/wiki/Dinorwig_Power_Station
Better still, adjust demand to it changes with supply by having electric cars with removable batteries, the batteries being recharged when there is excess power.
> Sure, you can couple wind and solar, but that still doesn't help when we get a valley fog inversion for most of January that reduces sunlight to 30% of already short days and no wind is blowing anywhere nearby.
Utah is connected to the rest of the USA. Is it ever not sunny and not windy everywhere?
Canada has already solved most of the typical nuclear problems with the CANDU design and ecosystem.
http://upload.wikimedia.org/wikipedia/commons/f/fe/CANDU_fue...
CANDU runs on natural uranium so the waste products are actually less radioactive than what we take out of the earth, as well CANDU can burn nuclear waste from light water reactors alleviating the need for Yucca mountain.
Lets look at it's meltdown profile, CANDU reactors need heavy water to function, if you replace the heavy water with light water fission stops, no meltdown. Also before the reactor would ever get to that point the fuel bundles deform, halting meltdown.
CANDU reactors are designed to put less radioactive material back into the earth than came out of it, and when problems occur in a CANDU design it fails safe.
>CANDU runs on natural uranium so the waste products are actually less radioactive than what we take out of the earth, as well CANDU can burn nuclear waste from light water reactors alleviating the need for Yucca mountain.
There is less uranium in the waste, but there will be fission products and trans-uranium elements just like in the fuel of regular reactors. Radioactivity of uranium is hardly a problem, when dealing with spent fuel. In short term (less than 100 years) fission products produce most of the radioactivity. In long term trans-uranium elements are the problem.
>Lets look at it's meltdown profile, CANDU reactors need heavy water to function, if you replace the heavy water with light water fission stops, no meltdown. Also before the reactor would ever get to that point the fuel bundles deform, halting meltdown.
Halting a normal fission chain reaction is hardly a source of accidents in any current nuclear reactor design. Decay heat is produced in the spent nuclear fuel of CANDUs just like in Fukushima or Three Mile Island.
CANDU is an interesting reactor design, but there is none as great alternative as you propose. However, various active and passive safety measures may get you very close. I don't know CANDU design so well, that I could judge those.
Interesting, I thought the large heat sink inherent in the CANDU design essentially ensured that with no human interaction that CANDU reactors would failsafe. My understanding was such that the 'reactor' might be destroyed but the design was such that the failure cascade would not release radioactive materials outside of the containment units.
As I said, I don't know the safety systems of CANDU :)
Large heat sink buys you time to get the cooling working again. Ultimately the heat must be transferred out somehow. In modern reactor designs these systems are usually designed to passively for very long times. With CANDU's it is very likely to be the case too.
In nuclear engineering one must always consider also the chance, that not everything is working as designed (like the destroyed diesel generators and external power sources at Fukushima). PRA (Probabilistic Risk Analysis) is used for that. PRA analysis are used for detecting most vulnerable systems in a nuclear power plant and this information is used to design new safer reactor types and to update the old ones little by little to be still safer. Harsh weather, seismic activity etc. is also considered in these analysis, but sadly in Fukushima even detected vulnerabilities didn't lead to improvements in time.
Even, if everything is done as well as possible, there is still a chance (although with modern designs almost arbitrarily small) that under certain conditions all the safety systems will fail. An ultimate example of such an event, would be a 100 km meteorite smashing the plant to atoms.
would be a 100 km meteorite smashing the plant to atoms
Or an airplane...
At least in European Union new nuclear power plants are designed to withstand a collision of any currently used commercial airplane.
That's nice. Except these facilities tend to last 50+ years, and planes keep getting bigger...
http://www.spiegel.de/international/germany/vulnerable-to-pl...
None of Germany's nuclear power plants is built after 2001. Before that hardly anyone cared about planes, when designing nuclear power plant.
None of Germany's nuclear power plants is built after 2001.
Yes. I guess we'll be fine if we just kindly ask those terrorists to not crash their planes into an older plant.
We agree on older plants being not as safe as new ones. My original sentence was about things you just can't prepare for (with any reasonable means). After that I just wanted to say, that it is possible to build plane-safe NPP.
Maybe yes, maybe no. Some CANDU negatives I'll chip in though: CANDU is one of the more successful vectors to creating nuclear-armed states; and it's not all that reliable - the uptime of the Bruce reactors is tolerable if you adopt a flexible definition.
Uranium fuels were never deployed because of cost or safety, they were deployed because various militaries funded the technology for use a) producing plutonium for weapons, and b) producing energy for large Navy customers.
Civilian nuclear energy based on the uranium fuel cycle is a spin off from a warfighter's R&D project.
Compare that with the thorium fuel cycle which does not produce weaponizable byproducts.
If anyone should know about funding military projects, it's a user named "politician"! :)
Generally when talking about how safe a given sort of nuclear power is the most important thing to consider is whether it has a positive void coefficient or not. That is, if the reactor starts to overheat will that make it generate more power or less. In light water reactors, such as pretty much all existing commercial reactors, you need complicated feedback systems to keep the reactor under control. And if those are damaged, as at Fukushima, you're looking at a melt down.
>Generally when talking about how safe a given sort of nuclear power is the most important thing to consider is whether it has a positive void coefficient or not.
The void coefficient is only appropriate, when you are dealing with a criticality accident like in Chernobyl. Criticality accident (fission chain reaction getting out of hand) has never happened in commercially used Western reactors. In fact, in Western countries you can not get a license for a reactor design, which has positive temperature coefficient for power i.e. the fission power must decrease, if temperature increases.