Why are so many people opposed to nuclear energy?

[Skyler4856]

Before anyone responds with a comment against nuclear energy, I would like to point out that is entirely possible (if not probable) that your computer is powered by nuclear energy.

[PakledHostage]

Both the major accidents each have a set of reasons why they happened and why they will never happen again, even if we were to construct dozens of new reactors.

Never underestimate the ability of people to come up with new and creative ways to have accidents. Chernobyl and Fukushima may be unlikely to happen again, but that doesn't mean that there won't be other accidents...

Just like nuclear power plants, transport category aircraft are operated and maintained by professionals, yet accidents still happen. It is often said that the aviation regulations are written in blood; the regulations are updated every time somebody invents a new way to have an accident. Take, for example, the shape of control knobs in cockpits. FAR 25.781 specifies the shape of each control. The shapes help pilots identify the correct control in low visibility and during lapses in concentration. Some might have claimed that there'd never be another accident due to a pilot activating the wrong control. Then along came the crew of China Eastern Airlines Flight 583: One of the flight crew accidentally deployed the leading edge slats when he dropped his clipboard. Two people died and 60 people ended up in hospital as a result of injuries sustained during the resulting upset. The MD-11's flap lever was originally designed to meet the requirements of FAR 25.781 but it wasn't enough. It was redesigned following the China Eastern Airlines accident.

yeah, teach both sides. where I've heard that one again. Frankly, one side made its case where the other failed to do anything but baseless fear mongering.

Thanks for helping me make my earlier point.

Edited October 31, 2013 by PakledHostage

[MBobrik]

Never underestimate the ability of people to come up with new and creative ways to have accidents. Chernobyl and Fukushima may be unlikely to happen again, but that doesn't mean that there won't be other accidents...

Surely they will be. but if reactors designed in 1950's had 1 accident per 25 years globally, 21 century's reactors will most probably have accident rates 1 per several centuries. Which is orders of magnitude safer than any other energy source. So talking about it as an argument against nuclear energy without wanting to abandon all other means of producing electric energy is hypocritical and irrational.

Thanks for helping me make my earlier point.

Let me repeat myself then. your side failed to produce a single valid rational argument against nuclear energy. and then proceeded to complain that it is not fair that we demand one.

EDIT: BTW good that you mentioned aircraft disasters. With aircraft it is almost the same. people are freaking out about a few high-profile disasters globally, while ignoring the plain fact that it is an order of magnitude more probable that they will die in a car accident. Yet a lot of people have flight phobia and virtually none is more scared of cars. something that kills 100 on one spot once per year is perceived as more dangerous than something that kills 10000 evenly distributed trough time and space. This thinking may be a common human flaw, but is nonetheless irrational. And so is radiation phobia.

Edited October 31, 2013 by MBobrik

[Anton P. Nym]

The great irony of the Fukushima accident is that more people died because of dam failures than from the reactor containment failure, yet the dams got nowhere near the level of coverage.

The great irony of the Three Mile Island accident is that if you took a bowl of cereal with a banana sliced into it, and poured on milk from cows that'd been downwind the day of the accident, the largest source of radioactivity would've been the banana slices.

Reactors have risks. So do hydroelectric dams, natural gas plants, and yes even solar and wind generation. I think we should look to using the right sources for the right jobs, instead of trying to find the One True Source. (Which doesn't exist, and would carry its own risks whatever the choice is.)

-- Steve

[lajoswinkler]

Well, I'm not sure I believe that you are unable to understand why. It would have been sensible to implement the infrastructure required for a particular fuel cycle as soon as we started using that fuel cycle. This is just common sense. Doing anything else is just delaying the inevitable.

Still no one answered why do we need to bury it. I'm still waiting.

I don´t understand the necessity to start calling names. If that´s the way you think you can win an argument so be it.

No sir, it was not to impress the Party and not illegal. https://www.youtube.com/watch?v=I7oDyuMssCY

Pulling almost all control rods from a RBMK is legal? Really? That's something new to me. A dry reactor made out of moderator with removed safety systems... That must be legal.

Wow, I just hope you'll never work in any power plant, because I wouldn't allow you to operate even an apartment boiler room. What you said is incredibly ignorant and there really is no use discussing nuclear technology with you. Sorry, but saying such things disqualifies you from further discussions.

What's promising about it? It reads like a religious discussion. Just about everyone who's expressed any concern about nuclear energy in this thread has been shot down as being stupid, irrational, a hippie or some combination thereof... Now we can add troll to the mix.

Risk management involves more than just simple statistics, and complex issues like the risks associated with nuclear or any other form of energy need intelligent discussion. There is almost certainly room for both sides of the argument to learn something, but this thread isn't turning out to be a forum where that can happen.

No, only people expressing utter ignorance have been kind of mocked. I too have concerns about nuclear technology and by all means I don't see it as a panacea to the energy crisis, but I'd never say stupid things like we see in this thread.

We can't really talk about risk management if people don't know what a RBMK is, what a cross section is, what's criticality, etc.

First you learn the basics, then you go forward. That's how things are done properly.

:/ Yeah okay I guess, it's not the best thread I've seen but I'm hoping it improves.

Though really, unless we get some actual nuclear physicists in here that's unlikely.

And how will we know if someone is a physicist? This is a forum. You have to believe what people say, and the only filter you have is your own knowledge about the subject matter. If you don't know anything about nuclear technology and physics, you can't make an informed choice, can you? It boils down to that.

Never underestimate the ability of people to come up with new and creative ways to have accidents. Chernobyl and Fukushima may be unlikely to happen again, but that doesn't mean that there won't be other accidents...

Just like nuclear power plants, transport category aircraft are operated and maintained by professionals, yet accidents still happen. It is often said that the aviation regulations are written in blood; the regulations are updated every time somebody invents a new way to have an accident. Take, for example, the shape of control knobs in cockpits. FAR 25.781 specifies the shape of each control. The shapes help pilots identify the correct control in low visibility and during lapses in concentration. Some might have claimed that there'd never be another accident due to a pilot activating the wrong control. Then along came the crew of China Eastern Airlines Flight 583: One of the flight crew accidentally deployed the leading edge slats when he dropped his clipboard. Two people died and 60 people ended up in hospital as a result of injuries sustained during the resulting upset. The MD-11's flap lever was originally designed to meet the requirements of FAR 25.781 but it wasn't enough. It was redesigned following the China Eastern Airlines accident.

Thanks for helping me make my earlier point.

Chernobyl will happen again if someone builds a big RBMK without containment and pulls out the safety systems. I think we can be safe that nobody will build it, unless the society goes backwards for some reason.

Contrary to the nuclear power plants, airplanes have killed enormous amounts of people. Should we abandon air traffic? If death toll per capita is important, some people go by the logic we should. That would throw this civilization to its knees.

I am concerned about some things about uranium fission reactors. It's the economic aspect. If something goes totally wrong in a modern power plant with containment, you've got lots of work to do. It costs money. If someone wanted to destroy such plant, he should target the powerlines and the backup electrical systems. No need for targeting the reactor.

It would be difficult for the plant operators to regain external power supply if you cut the plant off grid, and without diesel, there's only few hours before structural integrity of zirconium is compromised.

Partial meltdown is inevitable and that is enough to ruin the power plant. There is almost no contamination except few vented gases through the stack (namely iodine-131 and tritium), but the cost of cleanup is very high. TMI still stands there. Not much has been done.

Edited October 31, 2013 by lajoswinkler

[PakledHostage]

your side failed to produce a single valid rational argument against nuclear energy. and then proceeded to complain that it is not fair that we demand one.

And what side is "my side", exactly? Please show me where I wrote that I was against nuclear energy outright? All I ever advocated was caution in expanding our reliance on it because there are real risks associated with using it. Being cautious doesn't mean don't do it. I am a rock climber. I am also an engineer in a safety critical industry. I am cautious when I go climbing and when I sign an authorization, yet I still do both on a regular basis.

Although I have been following this thread for the past few days, I have been trying to stay out of it because it is full of ideologically motivated personal attacks. Clearly I should have exercised more self control...

[Mr Shifty]

yeah, teach both sides. where I've heard that one again. Frankly, one side made its case where the other failed to do anything but baseless fear mongering.

Curious how much experience you have actually working around nuclear technology? I, like TheSaint, spent several years babysitting nuclear reactors for the US Navy and currently work on fusion energy research. I have worn a radiation dosimeter for over a decade of my professional life. (I am wearing one as I type these words.) I stated far upthread that there are legitimate concerns about nuclear energy production that don't directly have to do with radiation exposure to people: nuclear plants are difficult and expensive to operate and maintain. They chew through materials and generate copious amounts of radioactive waste: not just spent fuel, but also water samples, air filters, valve parts, treatment chemicals, paint chips, etc etc etc. They require specialized materials and specialized designs, which makes building them and maintaining them expensive and difficult. It is easy to make a mistake with catastrophic consequences. In my Navy time I personally was either on watch for or assisted with clean up for: an unisolable feed leak in the steam system, a major chloride accident, rapid over-pressurization of a steam generator pressure vessel at low temperature because of a stuck relief, a feed loss that resulted in unbalanced neutron flux in the core, a main engine catastrophic failure and several other more minor casualties. All of these had the potential to cause core damage and/or high radiation exposure to personnel and/or loss of life.

And the radiation hazard isn't trivial. We look at accidents, but the Hanford site in Washington state is in the middle of a decades-long, multi-billion dollar clean-up. Lethal radiation doses have been found in ground soil there due to leaking storage tanks. Thousands of people have filed suit against the government because of an increase in thyroid cancer incidence likely due to the release of radioactive iodine isotopes. We who are radiation workers don't get lethal doses, but it's because we're very careful about radiation, not blase. There are large portions of the building I work in that will absolutely give you a lethal dose if you stand there when the machine is activated. And we have thick shield walls, a complicated series of locks, and double and triple-check personnel sweeps to make sure that doesn't happen. And we're a fusion facility, without the long-lived isotopes, super-heated and high-pressure fluids, and decay heat problems you have at a fission plant.

[MBobrik]

And what side is "my side", exactly? Please show me where I wrote that I was against nuclear energy outright? All I ever advocated was caution in expanding our reliance on it because there are real risks associated with using it. Being cautious doesn't mean don't do it. I am a rock climber. I am also an engineer in a safety critical industry.

... and, it seems, you are highly proficient in building straw men too. Do you think that nuclear energy proponents want us to stop being cautious or something ?

[Godot]

...

Just like nuclear power plants, transport category aircraft are operated and maintained by professionals, yet accidents still happen. It is often said that the aviation regulations are written in blood; the regulations are updated every time somebody invents a new way to have an accident. Take, for example, the shape of control knobs in cockpits. FAR 25.781 specifies the shape of each control. The shapes help pilots identify the correct control in low visibility and during lapses in concentration. Some might have claimed that there'd never be another accident due to a pilot activating the wrong control. Then along came the crew of China Eastern Airlines Flight 583: One of the flight crew accidentally deployed the leading edge slats when he dropped his clipboard. Two people died and 60 people ended up in hospital as a result of injuries sustained during the resulting upset. The MD-11's flap lever was originally designed to meet the requirements of FAR 25.781 but it wasn't enough. It was redesigned following the China Eastern Airlines accident.

...

ANother good example would be the collision of 2 aircraft that happened at the swiss german border almost a decade ago ...

2 planes (a russian one with school children on board and a german package transporter from DHL) collided because of an overworked air traffic controller misjudged the situation, several safeguards were switched off due to renovation operations and the pilot of the russian plane decided that it would be better to trust the air traffic controller than the on board TCAS system.

The collision would have ben avoided if the human factor hadn´t been involved (and all had depended on the automatic (TCAS) systems)

http://en.wikipedia.org/wiki/%C3%9Cberlingen_mid-air_collision

[TheCardinal]

This really is like a religous discussion: One side against the other. ("your side failed ...")

I don't see the point in following this thread any longer. All kinds of numbers and percentages are dropped into this thread as "proof", yet all of those numbers are based on assumptions and guestimates. Nobody knows the exact influence a radiation dose has on a persons life expectancy. Talking only of "incident related deaths" or just cancers excludes many important factors such as chronic disorders and health. Like so often the financial gains seem to be the most (if not the only) important thing.

Radiophobia is a nice buzz word used to silence opposing voices but in fact there's noone in his right mind who will eat fish caught in the sea in front of Fukushima. Doesn't that make us all radiophobic?

I'm willing to admit that i might be wrong. I don't know everything and never will. In this case i prefer to err on the side of caution. Better safe than sorry.

Cheerio!

[Drunken Hobo]

Reactors have risks. So do hydroelectric dams[...]

Indeed, just look at the Banqiao Dam disaster. A freak flood, not dissimilar to the freakish nature of the Japanese earthquake, caused the dam to burst and the resulting wall of water killed over 170,000 people. That's more than 40x the estimated death toll from Chernobyl.

Hydroelecticity also devestates areas of natural beauty, requiring huge reservoirs to operate. So where's the worldwide condemnation of hydroelecticity?

Don't get me wrong, I'm all for hydroelectricity and I think it's probably the best renewable energy resource we have at the moment (particularly as I live in a wet & hilly country), but again there is a downside to all power generation. No free lunch.

[Psycix]

This really is like a religous discussion: One side against the other. ("your side failed ...")

I agree, people should stop pointing out "sides".

It is impossible to discuss things if people enter a conversation with a "us vs them" mindset.

All kinds of numbers and percentages are dropped into this thread as "proof", yet all of those numbers are based on assumptions and guestimates. Nobody knows the exact influence a radiation dose has on a persons life expectancy. Talking only of "incident related deaths" or just cancers excludes many important factors such as chronic disorders and health.

Radiation induced cancer is pure chance.

Modeling with mathematical probability is the best approach, and relatively accurate.

Sure it is not spot-on (by definition), but it does run it down to the order of magnitude. It is very important to know if something kills dozens or thousands and conclusions should be drawn accordingly.

I dont think you should discard the numbers for being guesstimates while they are pretty meaningful.

Radiophobia is a nice buzz word used to silence opposing voices but in fact there's noone in his right mind who will eat fish caught in the sea in front of Fukushima. Doesn't that make us all radiophobic?

A fear is a natural impulse to preserve your own health or life. When this fear becomes excessive, it becomes a phobia.

Most of the population is indeed radiophobic: Their fear is excessive and does more harm to them than the radiation itself.

Being cautious about eating fish after a nuclear disaster is a good thing, but when radiotoxicity measurements prove the fish safe to eat*, I'd happily eat any fish out of the Fukushima sea, and so should everybody else!

*I do not know if this is the case right now, but that is not the point.

Edited October 31, 2013 by Psycix

[AlamoVampire]

Actually, we can do fusion very well (and no, not just H-bombs who use fission as 'sparkplug' for a fusion reaction).

Read up on JET and ITER.

JET hasn't produced more energy than is required to keep it running yet (though it theory, it should be capable of doing so, but they use it for other experiments). ITER is expected to produce about 10 times as much energy than in needs.

The last big hurdle fusion needs to take is finding a suiteble reactor wall material.

We need something that can hold up to a barrage of neutrons for an acceptable amount of time before needing replacement.

it is NOT an operational reactor, and any reaction we can do, is not sustainable at this time, so, no, we cannot do fusion reaction in any meaningful way. I stand by what I have said.

[lajoswinkler]

Curious how much experience you have actually working around nuclear technology? I, like TheSaint, spent several years babysitting nuclear reactors for the US Navy and currently work on fusion energy research. I have worn a radiation dosimeter for over a decade of my professional life. (I am wearing one as I type these words.) I stated far upthread that there are legitimate concerns about nuclear energy production that don't directly have to do with radiation exposure to people: nuclear plants are difficult and expensive to operate and maintain. They chew through materials and generate copious amounts of radioactive waste: not just spent fuel, but also water samples, air filters, valve parts, treatment chemicals, paint chips, etc etc etc. They require specialized materials and specialized designs, which makes building them and maintaining them expensive and difficult. It is easy to make a mistake with catastrophic consequences. In my Navy time I personally was either on watch for or assisted with clean up for: an unisolable feed leak in the steam system, a major chloride accident, rapid over-pressurization of a steam generator pressure vessel at low temperature because of a stuck relief, a feed loss that resulted in unbalanced neutron flux in the core, a main engine catastrophic failure and several other more minor casualties. All of these had the potential to cause core damage and/or high radiation exposure to personnel and/or loss of life.

And the radiation hazard isn't trivial. We look at accidents, but the Hanford site in Washington state is in the middle of a decades-long, multi-billion dollar clean-up. Lethal radiation doses have been found in ground soil there due to leaking storage tanks. Thousands of people have filed suit against the government because of an increase in thyroid cancer incidence likely due to the release of radioactive iodine isotopes. We who are radiation workers don't get lethal doses, but it's because we're very careful about radiation, not blase. There are large portions of the building I work in that will absolutely give you a lethal dose if you stand there when the machine is activated. And we have thick shield walls, a complicated series of locks, and double and triple-check personnel sweeps to make sure that doesn't happen. And we're a fusion facility, without the long-lived isotopes, super-heated and high-pressure fluids, and decay heat problems you have at a fission plant.

Wait wait wait wait...

You don't see something fishy about your second paragraph? Storage facility and iodine-131 scare? That isotope has a very short halflife time and when people get it into their thyroid, it's always because of an ongoing radiological disaster that involves uranium fission. You won't find iodine-131 in storage facilities. It decays rapidly. Cesium-137 yes, strontium-90 yes, but not iodine-131.

BTW nuclear submarine reactors run on heavily enriched uranium, with much more U-235 than civillian reactors use. Energy density is higher and the whole power plant is crammed into a small vessel. Comparing the dangers of such setup with civillian production of electricity is completely over the top.

You should know all this if you are who you claim.

This really is like a religous discussion: One side against the other. ("your side failed ...")

I don't see the point in following this thread any longer. All kinds of numbers and percentages are dropped into this thread as "proof", yet all of those numbers are based on assumptions and guestimates. Nobody knows the exact influence a radiation dose has on a persons life expectancy. Talking only of "incident related deaths" or just cancers excludes many important factors such as chronic disorders and health. Like so often the financial gains seem to be the most (if not the only) important thing.

Radiophobia is a nice buzz word used to silence opposing voices but in fact there's noone in his right mind who will eat fish caught in the sea in front of Fukushima. Doesn't that make us all radiophobic?

I'm willing to admit that i might be wrong. I don't know everything and never will. In this case i prefer to err on the side of caution. Better safe than sorry.

Cheerio!

It looks like a discussion between a scientist and a priest. One offers hypotheses and theories, the other one offer dogmas.

I guess it's easy to take a dump on a thread when you just decide to dignify all radiological investigations as "assumptions and guestimates".

When you can't offer arguments, it's best to start with denial. Well, cheerio to you, too.

[zxczxczbfg]

"1 picogram of cesium-137 dilluted in Atlantic ocean will cause 20 deaths in the next 500 years". Crap, but that's how statistics behaves at weird values.

Well, no. Cesium reacts quite exuberantly with water, and it is somewhat tricky to dilute something in something else when they're trying their darndest to explode. (Cesium salts on the other hand . . .) Plus, there's no way to track that small of an amount of Cs-137.

[lajoswinkler]

Well, no. Cesium reacts quite exuberantly with water, and it is somewhat tricky to dilute something in something else when they're trying their darndest to explode. (Cesium salts on the other hand . . .) Plus, there's no way to track that small of an amount of Cs-137.

In chemistry, when we talk about sodium, and don't explicitly say "elemental sodium" or "metallic sodium", we're talking about the element, not elemental matter.

That's why we can talk about daily sodium intake. Nobody will ever think there are chunks of alkali metal in our diet. In fact, that would be highly unpleasant as it would corrode our digestive system.

The same thing goes for radiological detection. Only few radioisotopes appear in their elemental form. Noble gases like krypton-85 are an excellent example.

Most of them appear as ions. The chemistry is the same. Unstable nuclei have nothing to do with chemical bonding, that's electron's business.

Cs-137 appears as Cs⁺. I think I-131 appears mostly as I^-, maybe there's some IO₃^-, too. Some of it might escape in elemental form (I₂), but I'm not sure. Iodine is highly reactive and will react with most metals at elevated temperatures, but the chemistry of meltdown is severely complex, so I can't claim such details. Immediate victims of Chernobyl were describing smell and taste similar to elemental iodine, but that might as well be because of the intense radioactivity of the dust floating around.

True, you can't track such small amounts, but you can work it out on paper and get wild stuff.

Edited November 1, 2013 by lajoswinkler

[RadHazard]

I think the benefits of Nuclear outweigh the risks by a large enough margin that we should continue to use it. As far as I know, these are the biggest issues with nuclear power:

- Long-term nuclear waste storage

- High construction costs

- Danger of meltdown or radiation release

- Dangers of uranium mining

- Risk of nuclear proliferation

- Decomissioning

Most of these problems can be lessened by solutions that are possible to implement now, or will be possible to implement in the near future.

Waste: Nuclear fuel can be reprocessed to capture something like 95% of the fuel, meaning waste is reduced by a factor of 20. Reprocessing does carry some risk of nuclear proliferation, as the reprocessing equipment can be used for enriching uranium. However, France has already demonstrated that reprocessing is a perfectly viable option, and the risk of proliferation is low, especially if undertaken by countries already in possession of nuclear weapons. Generation IV fast reactors are also capable of burning spent fuel without reprocessing. By implementing these reactors, we could skip reprocessing entirely, and some of them (breeder reactors) could even reprocess fuel on their own for use in themselves or other nuclear plants. There is still the issue of the (much smaller) volume of unusable waste. I believe that underground storage sites are quite safe, and that our nuclear casks are strong enough to safely transport waste to be stored.

Construction Costs: This is one of the biggest hurdles to effective nuclear. Nuclear plants are expensive to build. However, either government subsidies or increased financial pressure on the cheaper coal and gas plants (for example, requiring carbon capture and storage) would make nuclear much more economical in comparison. Considering the advantages nuclear gives, I would support this initiative.

Meltdown & Leak Concerns: Modern nuclear designs are very safe. There have been very few serious accidents concerning nuclear power. Both Chernobyl and, to a lesser extent, Fukashima, were as a result of lax safety standards. Chernobyl had far too many problems in reactor design, crew training, and operating procedures to list here. All design issues related to Chernobyl have been corrected in modern reactors, and crew training and operating procedures are much safer (and should be enforced more stringently by regulatory bodies). Fukashima had a fundamental flaw in that it's backup generators were vulnerable to flooding. This design flaw had been previously noted, but no attention was made to correct it. If tighter regulation enforcement is enacted, accidents of that scale can be prevented. Furthermore, the newest generation of reactors are much safer. Many Gen IV designs are "passively safe", meaning they have no danger of melting down even during a loss-of-coolant accident such as what happened in Fukashima.

Mining dangers: Uranium mining is a dangerous operation. However, by reprocessing old uranium and using fast reactors that burn nuclear waste, the amount of needed uranium drops sharply. While mining uranium will likely never be 100% safe, the much lower volume needed compared to coal means that the dangers are drastically reduced. Furthermore, uranium can be recovered from seawater in small amounts. The amount recoverable isn't favorable in the current climate, but if we start to reuse most of the fuel rather than discarding it, it could be a viable way to get fuel.

Proliferation: This is another big issue. It is difficult to prevent a non-nuclear-power from turning it's nuclear plant infrastructure into nuclear weapons programs. The best way to handle this is to closely monitor non-nuclear states carefully. This is not an easy task, but it's likely to be necessary regardless of whether we chose to build more plants. Nuclear states have no reason to pursue proliferation, and non-nuclear states that desire proliferation will likely want to increase their nuclear infrastructure regardless of the level of nuclear power in other countries.

Decommissioning: This is the final issue, and the only one that does not have a solution available. Nuclear plants, at the end of their operational lifetime, must be decommissioned. However, I believe that despite the high expense of this process, overall nuclear power is still a valuable resource.

By increasing the amount of nuclear power while simultaneously reducing fossil fuel plants, we greatly reduce the level of CO₂ and pollution emission. I suggest we follow a plan to use nuclear as a transitional energy source until a cleaner, safer source of energy that can replace it is found, such as this:

1. Begin reprocessing spent fuel, and increase safety regulation of existing plants.
   
2. Build both Gen III nuclear plants and renewable energy sources to reduce fossil fuel consumption.
   
3. Pursue Gen IV nuclear plants, and begin replacing decommissioned Gen II and III with new Gen IV plants.
   
4. Pursue clean alternative energy sources with the potential to replace fission. Replace decommissioned Gen III and IV (and V, if it takes that long) with this alternative source. Nuclear fusion has the most potential to fill this role, in my opinion.
   

I know that there are of risks, dangers, and problems associated with my suggested plan. However, I believe the risks, dangers, and problems associated with continuing to rely on fossil fuels, especially coal, are much worse.

it is NOT an operational reactor, and any reaction we can do, is not sustainable at this time, so, no, we cannot do fusion reaction in any meaningful way. I stand by what I have said.

I think this is all the more reason to fund ITER and it's planned successor, DEMO. ITER is planned to be the first nuclear fusion break-even achieved, with the capability to produce 10x the thermal energy (which could be converted into electricity at ~40% efficiency) as what is used to run the reactor at maximum power. ITER won't produce any electricity, but DEMO (which is to be designed based on what is learned from the construction of ITER) will. Economical Fusion power is still a fair bit away. However, it's closer now than ever, and we will eventually need something to replace fossil fuels or nuclear.

[Azivegu]

I don't understand this thing with activation energy. You do realize that fuel bundles inside a typical PWR require water to start the fission? Water serves as a moderator. If there is no water, and you pull out control rods, nothing fancy happens. So if the water boils away in uranium PWRs, its fission stops immediately.

What causes meltdowns is not uncontrolled fission, but decaying fission products heating up in the reactor devoid of coolant.

Thorium also produces fission products. Their composition is different, but they are there, and they will increase the temperature if not cooled down. I'm pretty sure problems can arise.

The only difference I see here is the fact that when uranium reactors start melting, they create a kind of lava which can melt through the thick steel vessel, and the initial lava has too much uranium dioxide close together, so hotspots of criticality can be created, but the material spreads and gets contaminated by steel and molten concrete below, so any fears of new criticality soon stop. That essentially happened in Chernobyl when the lava started dripping down. Its melting point is high so it's like spreading warm peanutbutter over cold bread. It sticks. It solidifies, too.

It does not accumulate in a neat little critical pond.

Thorium would be different because such drastic meltdowns could not happen, but to say any type of meltdown is impossible? No, that's just wrong. There are insanely radioactive fission products inside and they release heat, not to mention volatile isotopes which can escape (hence the need for containment dome, something Chernobyl lacked entirely).

What I am about to say is going to get very technical and it has been a while since I last read up on this, but I will do my best.

Uranium and Plutonium can create a self sustaining reaction. Water isn't really the moderator as it is the coolant. The problem is if the coolant is evicted from the vessel, it will cause a meltdown. (the graphite rods are only to control the speed of the reaction and keep it critical)

Thorium works best when it is dissolved in salts. This is also true for Uranium, but it can react violently. The benefit of salts is that you can heat it up to a much higher temperature and therefore get more 'bang for your buck.' Benefit of dissolving the fuel instead of using rods is that if the temperature gets too high, the fluid expands and less fuel is then present.

Thorium, unlike uranium or plutonium, cant sustain itself as its neutron emission=2 while U and Pu are >2. If neutron emission (how many neutrons it emits when the nucleus is hit) is<2 then it requires a constant feed of from an outside source to keep the reaction going and is thus not viable for energy production. if N<SUB>e</SUB> = 2 then the reaction will maintain itself (is critical) but needs a small little nudge every now and then to compensate for neutrons 'lost.' It is thus viable for energy production. If N<SUB>e</SUB> >2 you will constantly have to check it to see that it isn't going supercritical which could lead to heat buildup.

So thorium is more inherently safe because if it is left to its own device, it will just shut down and there will not be a melt down. That sadly isn't the case for U or Pu.

And when there is a meltdown you usually aren't to worried about the uranium as you are about things like Strontium or Polonium. Thats the really nasty stuff. But pretty much anything that emits alpha particles is worrisome.

What they did at Oakridge when they were testing thorium, was make use of a so called 'cold-plug.' There would be, connected to the system running the molten salt thorium mixture (called a Liquid Fluoride Thorium Reactor (LFTR)) a small pipe that was constantly cooled. This pipe would lead to a well sealed chamber where in case of a power outage the cooling of the plug would halt (as it requires energy) and all the material would drain away a solidify. They did this every Friday before they went home and when they came back Monday they would heat it up and pump it back in. It wasn't necessary, but they didn't want to come back in the weekend to check everything and this was cheaper. It worked really well. The benefit of it is that it is passively safe (doesn't requires energy to activate the safety mechanisms) instead of actively safe (requires energy to control situation) like it is for U and Pu.

For U and Pu you must constantly pump the water, control the rods and have active backup systems that all require power. That was the major downfall in Fukushima. Once you knocked out the generators, the **** hit the fan.

I personally think Uranium is a good source of power and that we should progress with thorium based reactors. Fussion is going to be a long ways away. Solar and wind are great as a backup energy, but I wouldnt recommend it seeing the vast quantities of REM's in them like Neodynium. A thorium reactor station about half the size of New Hampshire would be enough to power the entire US, whilst an area the size of west virginia is needed for windmills.

[lajoswinkler]

What I am about to say is going to get very technical and it has been a while since I last read up on this, but I will do my best.

Uranium and Plutonium can create a self sustaining reaction. Water isn't really the moderator as it is the coolant. The problem is if the coolant is evicted from the vessel, it will cause a meltdown. (the graphite rods are only to control the speed of the reaction and keep it critical)

Thorium works best when it is dissolved in salts. This is also true for Uranium, but it can react violently. The benefit of salts is that you can heat it up to a much higher temperature and therefore get more 'bang for your buck.' Benefit of dissolving the fuel instead of using rods is that if the temperature gets too high, the fluid expands and less fuel is then present.

Thorium, unlike uranium or plutonium, cant sustain itself as its neutron emission=2 while U and Pu are >2. If neutron emission (how many neutrons it emits when the nucleus is hit) is<2 then it requires a constant feed of from an outside source to keep the reaction going and is thus not viable for energy production. if N<SUB>e</SUB> = 2 then the reaction will maintain itself (is critical) but needs a small little nudge every now and then to compensate for neutrons 'lost.' It is thus viable for energy production. If N<SUB>e</SUB> >2 you will constantly have to check it to see that it isn't going supercritical which could lead to heat buildup.

So thorium is more inherently safe because if it is left to its own device, it will just shut down and there will not be a melt down. That sadly isn't the case for U or Pu.

And when there is a meltdown you usually aren't to worried about the uranium as you are about things like Strontium or Polonium. Thats the really nasty stuff. But pretty much anything that emits alpha particles is worrisome.

What they did at Oakridge when they were testing thorium, was make use of a so called 'cold-plug.' There would be, connected to the system running the molten salt thorium mixture (called a Liquid Fluoride Thorium Reactor (LFTR)) a small pipe that was constantly cooled. This pipe would lead to a well sealed chamber where in case of a power outage the cooling of the plug would halt (as it requires energy) and all the material would drain away a solidify. They did this every Friday before they went home and when they came back Monday they would heat it up and pump it back in. It wasn't necessary, but they didn't want to come back in the weekend to check everything and this was cheaper. It worked really well. The benefit of it is that it is passively safe (doesn't requires energy to activate the safety mechanisms) instead of actively safe (requires energy to control situation) like it is for U and Pu.

For U and Pu you must constantly pump the water, control the rods and have active backup systems that all require power. That was the major downfall in Fukushima. Once you knocked out the generators, the **** hit the fan.

I personally think Uranium is a good source of power and that we should progress with thorium based reactors. Fussion is going to be a long ways away. Solar and wind are great as a backup energy, but I wouldnt recommend it seeing the vast quantities of REM's in them like Neodynium. A thorium reactor station about half the size of New Hampshire would be enough to power the entire US, whilst an area the size of west virginia is needed for windmills.

Wait, what kind of reactor are you describing? I am talking about pressurized water reactor, the best and the most abundant of them all.

Water is the moderator and a coolant. There are no graphite rods, only fuel rods and cadmium control rods. Water keeps the criticality. If bubbles of steam occur in the primary loop, criticality is greatly harmed and the reactor needs to be shut down. There is a complex protocol how to establish criticality. It's about the geometry of the control rods and the order of pulling them out.

Again, meltdowns are not caused by the reactors having too much fission. Meltdowns occur when the chain reaction is gone and the coolant evaporates, so the fission product decay heat increases the fuel bundle temperature above tolerable limit. The bundle matrix sags down and hotspots start to appear, etc. It usually happens in thenext few hours after reactor shutdown.

Does thorium produce such crazy fission products? Yes it does, but the design has molten fluoride salt matrix so there is no immediate danger of corium blowing a hole and munching down on concrete below. I've already explained it.

I'd like to see thorium reactor development, as it is still not commercially viable, but we need to build 4th generation uranium fission power plants. Those systems are unbelieveable and not exactly many people know about it. The best you can expect is that a person knows the basics of PWR and BWR.

There is CANDU, too. Very cool design.

[ThatBum]

I, uh...I'm just gonna put this in here:

http://www.bbc.co.uk/news/science-environment-24429621

Yeah.

[Unit327]

I see renewables as a superior solution, and ultimately the end goal of where we want to be. No need to mine, no waste to dispose of, and practically endless supply. Sure there is more research that needs to be done before they can completely supply all of our power needs, but I don't think that's so far off that we should invest heavily in stop gap measures like nuclear (fission). Temporary solutions have a way of becoming permanent, and I think it would kill the incentive to research renewables. I want my orbital solar microwave death ray power station please.

Most renewables also have the benefit of decentralisation and distribution being much easier than with nuclear. This makes them ideal for developing countries as well.

[Mr Shifty]

Wait wait wait wait...

You don't see something fishy about your second paragraph? Storage facility and iodine-131 scare? That isotope has a very short halflife time and when people get it into their thyroid, it's always because of an ongoing radiological disaster that involves uranium fission. You won't find iodine-131 in storage facilities. It decays rapidly. Cesium-137 yes, strontium-90 yes, but not iodine-131.

I may have been unclear. The I-131 was emitted as a gas during the reactor's operation. Folks who are suing were the 'downwinders' exposed for many years while the reactor was operational. Clean-up is a separate issue and has been a boondoggle. The whole facility stinks of mismanagement and lax regulation. I'll admit that those aren't necessarily technical problems, but that's kind of the point.

BTW nuclear submarine reactors run on heavily enriched uranium, with much more U-235 than civillian reactors use. Energy density is higher and the whole power plant is crammed into a small vessel. Comparing the dangers of such setup with civillian production of electricity is completely over the top.

You should know all this if you are who you claim.

I was on an aircraft carrier, but your point is apropos. I know very little about civilian plants except by analogy, but I'm assuming that a PWR is a PWR. And by looking at DoE inspection reports for civilian reactors it seems they have many of the same issues with materials, water chemistry, failure modes that naval plants do (e.g. the steam generator u-tube degradation at San Onofre or reactor vessel corrosion at Brown's Ferry.) True that naval plants use HEU, and perhaps having a lower neutron flux density in the core might have mitigated one of the casualties I described (power peaking and uneven fuel use due to unbalanced coolant flow.) And like fossil-fuel fired plants, much of the personnel danger is due to the steam plant, not the reactor side, but steam plant casualties in a nuclear plant have the added complication of affecting the reactor (e.g. a rupture in the steam system can cause a cold water excursion that could overpower and damage the core.) It is telling that as a plant supervisor, 95% of what I did during operation was materials management through water chemistry and tight temp/pressure control to prevent brittle fracture. And the most dangerous things we did were not operations, but maintenance -- by several orders of magnitude.

[RadHazard]

I see renewables as a superior solution, and ultimately the end goal of where we want to be. No need to mine, no waste to dispose of, and practically endless supply. Sure there is more research that needs to be done before they can completely supply all of our power needs, but I don't think that's so far off that we should invest heavily in stop gap measures like nuclear (fission). Temporary solutions have a way of becoming permanent, and I think it would kill the incentive to research renewables. I want my orbital solar microwave death ray power station please.

Most renewables also have the benefit of decentralisation and distribution being much easier than with nuclear. This makes them ideal for developing countries as well.

While a world powered by renewable energy would be a wonderful thing, I don't know how possible it is. Most renewables are either heavily location dependent (geothermal, hydro, wind somewhat), erratic (solar, wind again), or have a low energy density (solar, meaning they work better as suppliments rather than the main energy supply. Orbital solar power stations are a potential solution, but they are a long way away. Though it will hopefully improve with time, as of now space travel is far too expensive to allow such a system to be economic.

I still think we need something to bridge the gap between now and when we develop a clean, economical solution that doesn't have these drawbacks, and I'd prefer something cleaner than coal. If you're worried about nuclear fission becoming a permanent solution, it's not likely to happen if we develop an economical alternative, since all reactors need to be decommissioned after 50-60 years of operation. I think it's very likely that it will take at least that long before we have developed clean energy to the point in which it can provide 100% of our total energy requirement.

[Unit327]

This big picture science podcast is handy: http://radio.seti.org/episodes/Power_to_the_People

Guests:

W. Bernard Carlson – Professor of science, technology and society, University of Virginia, and author of Tesla: Inventor of the Electrical Age

Michael Dunne – Physicist, program director for laser fusion energy, Lawrence Livermore National Laboratory

R. Tom Baker – Chemist, director of the Center for Catalysis Research and Innovation, University of Ottawa

Paul Young – Radio engineer, director of Powersat Ltd.

Theresa Levitt – Historian, University of Mississippi, and author of A Short Bright Flash: Augustin Fresnel and the Birth of the Modern Lighthouse

Stuff like solar sattelites aren't "a long way off" because the engineering is insurmountable. It's just that the research funding, investors and economic incentives aren't there (yet).

[AlamoVampire]

<blinks> wow, this threads still alive, more impressively, we all seem to be calm and frighteningly rational in our arguments! Way to go all of us! No really!!