The Nuclear Power Thread

[JaredJames]

Yes, you need extra power lines to the places that were powered by plants that were previously shut down. To the local places where the mix is much more than 30% nuclear.

That's neither how the grid is designed or works.

Supply and demand man, supply and demand. You have a cut in supply, you have same demand, you raise the price, that leads to decrease in consumption, to match the supply. Raise the price 2x and a lot of stupid uses of electricity (like heating) will rather quickly disappear, while the more energy efficient things will get huge edge over less energy efficient things.

That has nothing to do with what I said or was commenting on.

Regardless, you can't just "cut people off" or raise prices so no one can afford it.

In modern day terms, that's barbaric. I think you are bordering on trolling now, claiming heating is a "stupid use" of electricity - it is an essential use.

 

[Joseph Chikva]

you raise prices high enough for consumption to go down, then you may need to add power lines, then you shut off bunch of plants. A bunch of plants, incidentally, ARE shut down due to quakes, so don't tell its impossible. There's nothing impossible about it. Inconvenient, yes, but if wind starts blowing inland from Fukushima, that's going to seriously piss people off.

You guys are probably working in nuclear industry. or are supportive of, and you're being real optimistic about your industry's future. I'm being realistic.

I do not work in nuclear industry. But together with raising prices on 1kWh you would get economics growth down. Accordingly you will get unemployment, competitiveness lowering etc.
Because there are some energy intensive industries being very critical to price on electricity. Do you propose to annihilate e.g. steel production industry in Japan?
When consumption will go down for what are you going to add power lines?
Earthquakes in Japan are happening permanently. But Fukushima is only the first serious accident with such aftereffects.

 

[Dmytry]

In modern day terms, that's barbaric. I think you are bordering on trolling now, claiming heating is a "stupid use" of electricity - it is an essential use.

See, man, using primarily fossil electricity for heating is immensely ineffective versus using the heat from fossil fuels directly. HOWEVER it is attractive due to simplicity (laying and maintaining pipe for centralized heating costs money). My house is heated using centralized heating.

On topic of extra lines: You two want to assume that i am some sort of moron who thinks that power lines make extra electricity or something? Nevermind that I gave you two huge benefit of the doubt, assuming that you had some sort of intelligent argument, such as - the 30% is the national average, suppose that southern japan has 40% nuclear and northern has 20%, then you may need extra capacity for long range transmission. Thats especially clear in case of european union. Then the renewables like wind, which require long range transmission to minimize downtime.

Barbaric, yeah, nowadays it is totally barbaric not to have advertisements lit up all the time, or to use centralized heating, or to opt for more efficient air conditioning that is also more expensive to install.

Whenever they actually will or won't get rid of nuclear, that's open question. I would guess that they won't get rid of nuclear. But you guys better don't assume that nuclear is here to stay no matter how many regulations you violate on any given day or how badly the reactors are designed (rods falling out resulting in criticality. what the hell?!)

 

[Joseph Chikva]

See, man, using primarily fossil electricity for heating is immensely ineffective versus using the heat from fossil fuels directly. HOWEVER it is attractive due to simplicity (laying and maintaining pipe for centralized heating costs money). My house is heated using centralized heating.

On topic of extra lines: You two want to assume that i am some sort of moron who thinks that power lines make extra electricity or something? Nevermind that I gave you two huge benefit of the doubt, assuming that you had some sort of intelligent argument, such as - the 30% is the national average, suppose that southern japan has 40% nuclear and northern has 20%, you may need extra capacity for long range transmission. Then the renewables like wind, which require long range transmission to minimize downtime.

I think nobody spoke anything offensive.
But your idea about rising of prices for electricity consumption reduction doesn't withstand criticism.
I would like to recall you that world economics is very critical to changing of interbank interest rate even only on a few tenths of percents. And you are proposing to increase the prices in Japan on order of magnitude.
And I do not understand if we should decrease power output why new power lines are required? Existing lines have not enough capacity? What additional transmission capacity will be demanded when generation will decrease?

 

[Dmytry]

Long range transmission is typically done differently (HVDC) to minimize the losses.
Really, I don't know why I even bother. I go as far as to think for your side and mention a problem with switching off nuclear power - that you may first need extra lines for long range transmission. Turns out its an issue you don't understand.

 

[Joseph Chikva]

Long range transmission is typically done differently (HVDC) to minimize the losses.
Really, I don't know why I even bother. I go as far as to think for your side and mention a problem with switching off nuclear power - that you may first need extra lines for long range transmission. Turns out its an issue you don't understand.

Dear Dmytry, if we have a task of optimization (minimization) of energy losses, yes, I do not understand why the line constructed for transmitting of higher generation would not transmit the lower. I admit that in case of change of generation schedule when some plants won't work, the existing transmitting lines network can become nonoptimal. But it isn't obvious to me yet.
And it does absolutely not required to me “your staying on my side”. As your proposal to reduce power generation in Japan is unacceptable firstly for Japanese (not for me). Because it will no doubt kill many branches of their industry.

 

[Borek]

A bunch of plants, incidentally, ARE shut down due to quakes, so don't tell its impossible.

At the moment that means rolling outages (or have they already stopped), plus substantial part of the industry and housing is destroyed (so they don't consume electricity). I see your point, but you are oversimplifying to the absurd level just to support it.

That being said I agree we are in general wasting energy and it is possible to get the use down, there were threads at PF where these things have been discussed (even on a household level).

 

[Joseph Chikva]

That being said I agree we are in general wasting energy and it is possible to get the use down, there were threads at PF where these things have been discussed (even on a household level).

Yes, we are wasting energy and can use less for the same job. But how to use less when for one metric ton of aluminum production as I remember about 13'000 kWh required?
Dmytry proposes to increase prices on electricity for reducing consumption.

 

[Dmytry]

At the moment that means rolling outages (or have they already stopped), plus substantial part of the industry and housing is destroyed (so they don't consume electricity). I see your point, but you are oversimplifying to the absurd level just to support it.

Well I know I'm oversimplifying, but apparently not to level absurd enough for this thread - I see I should of simply omitted the whole 'need for more lines' issue.

That being said I agree we are in general wasting energy and it is possible to get the use down, there were threads at PF where these things have been discussed (even on a household level).

Ya, and to get the use down, you raise the price, for the alternatives to be economically viable. Heating for example is a major use of electricity that can over time be rid of by use of heat directly, especially in a place that uses mostly fossil fuels. There is a lot of cases where a lot of electricity is spent literally as a matter of convenience. That can't be done overnight, but I never said it can. Over several years yes. In the industry, too, there is a lot of cases whereby it is a lot cheaper to use electric heater than to have an on-site fossil heat source - due to cost of white collar and blue collar labour involved in designing and setting it up, not the cost of resources.
Look at the oil. Prices rise and oil consumption goes down. You know, I am not worried about peak oil. Why am I not worried? Because as the cost of resources rises, this creates demand for the blue and white collar work involved in optimization.

I'm not saying it should be done. I do think that coal power is a lot worse than nuclear power. I'm saying that it CAN be done. And to some extent, it definitely should (cull the least safe reactors). The nuclear power proponents should understand this.

edit: also, for the impact of Fukushima on nuclear power worldwide: the pro nuclear experts quoted in this article
http://www.bbc.co.uk/news/science-environment-12711707
did more damage to future of nuclear power than Greenpeace can ever dream of (ditto for similar articles published elsewhere on 11th March). Nuclear optimism kills nuclear power. Now every pro nuclear expert is going to speak of how Japanese can't get rid of nuclear. Then, heaven forbids, Japanese start phasing out nuclear power and get rid of it - what's then? Really, why 'pro nuclear' experts just keep, as the Russian proverb goes, stepping onto same rake? Making ultra optimistic predictions that don't play out. Hell, even making predictions that might not play out - gambling severely.

edit: to clarify this even better. The public doesn't think like "ahh, if the pipe A breaks, the valve B prevents the accident, if valve B gets stuck, the pressure relief valve C breaks open... very clever, looks safe". No, the member of the public looks at the nuclear expert, and thinks - Can I trust this guy? Does he have a clue what he's speaking of? . Regular Joe looks at the expert on 11th March, talking about Fukushima, and he hears, nuclear power has a lot of backups and backups for the backups, everything's going to be fine. Then the regular Joe looks at this issue again, and he's, wow, nobody ever told me all that stuff is in basement, etc. Joe ain't going to look at blueprint and trace pipe A to a valve B. Joe's going to look at expert and evaluate his words, and Joe ain't going to trust safety to such optimists.
Furthermore, and this may seem illogical, but it is a very common heuristic - if someone's been so wrong, their words acquire *negative weight*. When the same discredited expert tells how nuclear energy is safer than coal - that is a strongest anti nuclear propaganda possible.

 

[Joseph Chikva]

Well I know I'm oversimplifying, but apparently not to level absurd enough for this thread - I see I should of simply omitted the whole 'need for more lines' issue.
Ya, and to get the use down, you raise the price, for the alternatives to be economically viable.

Now you began to say about viability level of prices rising. But the main difficulty is in the different dependence on electricity prices in different industries. I can miss some branches but now can maintain the most depended are aluminum production and chlorine production. Do you propose average level of price rising? You will kill these two.

Heating for example is a major use of electricity that can over time be rid of by use of heat directly, especially in a place that uses mostly fossil fuels. There is a lot of cases where a lot of electricity is spent literally as a matter of convenience. That can't be done overnight, but I never said it can. Over several years yes. In the industry, too, there is a lot of cases whereby it is a lot cheaper to use electric heater than to have an on-site fossil heat source - due to cost of white collar and blue collar labour involved in designing and setting it up, not the cost of resources.
Look at the oil. Prices rise and oil consumption goes down. You know, I am not worried about peak oil. Why am I not worried? Because as the cost of resources rises, this creates demand for the blue and white collar work involved in optimization.

The matter is in the some trigger level on prices after which usage of fossil fuel vs. electricity will not be expedient. And this level differs in different industries. And if prices on crude will reach that level you will see more and more electric industrial heaters instead of fuel burning.

I do not try to save nuke industry, but I really do not see the real alternative.

And what your fellow countryman Mendeleyev has told about crude oil burning? "This is the same that banknotes burning". But we burn them (banknotes) and in very big ammounts.

 

[JaredJames]

Ya, and to get the use down, you raise the price, for the alternatives to be economically viable.

The alternatives are not capable of meeting demand. Especially in a country such as Japan where you have little room to place them.

Wind and solar power require far too much room, hydro could compete, but where do they put all those lakes and dams?

That's why they aren't economically viable.

This applies to anywhere that doesn't have the climate or space to locate the required amounts of renewable sources.

I'm also curious, why the power companies would raise the price and price themselves out of the competition? It's not what businesses do. You are talking about having power companies effectively commit suicide on those plants by making this move.

Regarding waste: I completely agree we waste a lot. But that doesn't make heating "stupid".

 

[Dmytry]

"The alternatives are not capable of meeting demand"
How do you know that? Did you count the alternatives such as burning coal on industrial site to produce the heat, instead of using electric heating? Or did you just go - hydro and solar and wind can't replace nuclear?

Japan's electricity is primarily made in coal burning plants, do you know that? I'm not speaking of the fluffy hydro and renewables, I've been making this abundantly clear. I'm speaking of the big bad coal that kills more people than nuclear could, replacing the nuclear. Hydro also sucks by the way. Downstream from the dam, if the dam is destroyed, you get artificial tsunami.

I'm not saying it is good to replace nuclear with coal. In my opinion actually it is bad to replace nuclear with coal. What I am saying, is that it CAN happen, and just because it is bad, does not mean it won't happen, and it is furthermore very dumb of pro nuclear crowd to be optimistically telling how it can't happen, and risk to have it happen. Nuclear industry already lost enormous amount of face.

"I'm also curious, why the power companies would raise the price and price themselves out of the competition?"
lol, so suddenly there is competition that'd bring price down / provide it at lower price. Interesting, interesting.

 

[JaredJames]

"The alternatives are not capable of meeting demand"
How do you know that? /Did you count the alternatives such as burning coal on industrial site to produce the heat, instead of using electric heating? Or did you just go - hydro and solar and wind can't replace nuclear?

What does that have to do with anything? The alternative sources cannot, on a reasonable scale, produce enough electricity to cover the demand of a nuclear plant.

I am discussing renewable alternatives not fossil fuels. Going from nuclear to fossil fuel is a step backwards.

Japan's electricity is primarily made in coal burning plants, do you know that? I'm not speaking of the fluffy hydro and renewables, I've been making this abundantly clear. I'm speaking of the big bad coal that kills more people than nuclear could.

You think they should switch to coal? A step backwards if I've ever heard it. The death rates from that are through the roof.

You're arguing nuclear isn't safe and it's bad and they should force people to switch to alternate supplies such as coal, yet the death rates from nuclear including Chernobyl (and now Japan) are still far lower than coal. Where is the logic in that?

Whether people like it or not, the death rate from nuclear is significantly lower than coal and it is far safer. There is no argument that "we should switch to coal because it's better". If we are willing to accept the deaths from coal, why are we up in arms over nuclear when it has less deaths anyway? On a risk of death scale, nuclear ranks far better than coal.

I don't see the nuclear industry losing face - I see a lot of public panic generated by the media.

lol, so suddenly there is competition that'd bring price down. Interesting, interesting.

Where do you live? This is how business operates. Of course there is competition that brings the price down. No business is going to artificially inflate the price of their nuclear supply so no one can afford it - lose customers, which lowers demand - which means they have no reason to build new coal plants - would you spend billions when there's no money coming into cover it and no demand there?

 

[Astronuc]

A very interesting discussion on the current state of nuclear energy in the US -

Nuclear Power: Setting Sun?
http://www.commonwealthclub.org/events/2011-04-08/nuclear-power-setting-sun

Jacques Besnainou, CEO AREVA Inc.
Lucas Davis, Professor, Haas School of Business, UC Berkeley
Jeff Byron, Former Commissioner, California Energy Commission

 

[Dmytry]

What does that have to do with anything? The alternative sources cannot, on a reasonable scale, produce enough electricity to cover the demand of a nuclear plant.

I am discussing renewable alternatives not fossil fuels. Going from nuclear to fossil fuel is a step backwards.You think they should switch to coal? A step backwards if I've ever heard it. The death rates from that are through the roof.

You're arguing nuclear isn't safe and it's bad and they should force people to switch to alternate supplies such as coal, yet the death rates from nuclear including Chernobyl (and now Japan) are still far lower than coal. Where is the logic in that?

Whether people like it or not, the death rate from nuclear is significantly lower than coal and it is far safer. There is no argument that "we should switch to coal because it's better". If we are willing to accept the deaths from coal, why are we up in arms over nuclear when it has less deaths anyway? On a risk of death scale, nuclear ranks far better than coal.

For 10th time. I'm not saying what they should or should not do. I'm saying what they may do. I'm even saying why it is bad (more deaths I'd guess). Where is the logic you ask? Where is the logic in using primarily coal? Or where is the logic in starting a project to develop Japanese equivalent of KHG but drop the project 1 year in? Or where is the logic in getting 2 robots, one with hand held radiation monitor other to look at it, instead of 2 robots capable of measuring radiation? There isn't logic. There's actions - and consequences.

Seriously, I'm getting impression there that pro nuclear people want to be elite underground (vs convincing anyone that nuclear has future).

 

[clancy688]

Seriously, I'm getting impression there that pro nuclear people want to be elite underground (vs convincing anyone that nuclear has future).

And I'm getting the impression that the contra nuclear people want to be elite underground as well, convincing everyone that nuclear power has no future.

scnr

 

[Dmytry]

If only. So far I can't even convince pro-nuclear that Fukushima even in principle could damage nuclear industry big time. They don't see the logical reason why it should, so the idea is that it won't.

 

[Astronuc]

If only. So far I can't even convince pro-nuclear that Fukushima even in principle could damage nuclear industry big time. They don't see the logical reason why it should, so the idea is that it won't.

Sure it will have an effect - and it has.

NRG withdraws from Texan project
http://www.world-nuclear-news.org/NN-NRG_withdraws_from_Texan_project-2004114.html
20 April 2011

Italian government puts brakes on nuclear vote
http://www.world-nuclear-news.org/NP_Italian_government_puts_brakes_on_nuclear_vote_1904112.html
20 April 2011

 

[Dmytry]

In soviets, head of minatom IIRC said something like, science requires sacrifice. After Chernobyl. A great pro-nuclear advocate he was, eh. I think what was really bad about Fukushima, is all the 11th coverage and news exceeding the worst expectations. I really wouldn't bet my money that Japanese won't start phasing out nuclear.
Just for laughs I looked up insurance rates on nuclear power plants. They apparently estimated 1/1000 probability of $300M liability accident per reactor year, that order of magnitude (collecting 400K$/year per reactor, max payment around 300M , that's for liabilities). Then there is
http://en.wikipedia.org/wiki/Price–Anderson_Nuclear_Industries_Indemnity_Act
It would seem to me that economically speaking, nobody's - not owners either - are trusting those immensely low risk figures that have been circulating (1 in 30 000 core-years etc), nobody's willing to bet a lot of money that those figures are correct.
I really dunno, if a nuclear plant is to be constructed near my house - why exactly should I trust it more than an insurance firm would? Which gives it 1% probability of serious accident in 10 years for single reactor, which in my book is a little on the not so nice side to be honest. Sure I'd rather live next to NPP than to coal fired plant, but i'd even rather have my own solar panel and energy storage, even if it costs a lot more. And I'd definitely invest in radiation monitor that is on 24/7 . 1% per 10 years is not very good neighbourhood.

 

[edpell]

LFTR (liquid fluoride thorium [nuclear] reactor) looks like a good solution to our energy needs. Lots of info at www.energyfromthorium.com An initial charge of U233 is used to breed U233 from a thorium blanket and produce energy.

It produces much less waste and the waste is shorter lived. It uses only room pressure unlike LWR that use high temperature water under high pressure to keep it from flashing to high pressure, high temperature steam (hence the need for the large thick pressure dome in case of failure not needed with liquid thorium fluoride/liquid uranium fluoride).

This type of reactor was run at Oak Ridge in the 1960s and is under development in France and China currently. Once they have a large source of electricity they can make synthetic methanol and dimethyl ether for transportation fuels.

 

[Astronuc]

Non-proprietary presentation to NRC by GEH/GNF on current technology developments.
http://pbadupws.nrc.gov/docs/ML1027/ML102700236.pdf (~24 MB file, so use save target as)

 

[zapperzero]

LFTR.

Liquid uranium fluoride. 800 degrees Celsius or even more, for process heat applications. No containment. Heat exchanger where water is separated from molten fluoride salt by just the thickness of a steel pipe, that's supposed to last decades, without embrittling from either fluorine or neutrons.

A radioactive fuel re-processing plant that deals with molten fluoride salts, next to every reactor. Plutonium, produced and separated on an ongoing basis.

If the thought of all this doesn't send a chill up your spine, I don't know what will.
There is a reason why those reactors never got past technology demonstrator phase. The knowledge needed to make them reliable just wasn't there. It still isn't.

 

[zapperzero]

No business is going to artificially inflate the price of their nuclear supply so no one can afford it - lose customers, which lowers demand - which means they have no reason to build new coal plants - would you spend billions when there's no money coming into cover it and no demand there?

http://en.wikipedia.org/wiki/Enron#California.27s_deregulation_and_subsequent_energy_crisis

An energy producer artificially inflating price and thus driving demand destruction. The price point where maximum profit ratio is found is never the point at which the most units of a certain product could be sold.

EDIT: that's partly because nothing in the energy markets really is a fungible commodity, electricity least of all.

 

[mheslep]

EDIT: that's partly because nothing in the energy markets really is a fungible commodity, electricity least of all.

? Nearly the opposite is true, as most fuels are close to being commodities especially in raw form, less so the as they are processed, modified, and blended to meet the regulations of particular local markets.

 

[mheslep]

Liquid uranium fluoride. 800 degrees Celsius or even more, for process heat applications.

I speculate that most engineers would rather deal with a high temperature, low pressure system than a lower temperature, high pressure (153 atm for a light water PWR) system.

No containment. Heat exchanger where water is separated from molten fluoride salt by just the thickness of a steel pipe, that's supposed to last decades, without embrittling from either fluorine or neutrons.

A radioactive fuel re-processing plant that deals with molten fluoride salts, next to every reactor. Plutonium, produced and separated on an ongoing basis.

Reprocessing from the spent fuel of a U235 light water reactor produces Pu upon re-processing, not so for Th based LFTR (in significant amounts).

...
There is a reason why those reactors never got past technology demonstrator phase.

Yes, and that's well known to be the need for an infrastructure that lent itself to making weapons grade material, not reliability. http://www.wired.com/magazine/2009/12/ff_new_nukes/all/1"

Uranium reactors had already been established, and Hyman Rickover, de facto head of the US nuclear program, wanted the plutonium from uranium-powered nuclear plants to make bombs. Increasingly shunted aside, Weinberg was finally forced out in 1973.

 

[zapperzero]

? Nearly the opposite is true, as most fuels are close to being commodities especially in raw form, less so the as they are processed, modified, and blended to meet the regulations of particular local markets.

Fuels are rarely if ever blended. There's sweet crude, light crude, heavy crude, sour crude... quality differences which are reflected in the price and sometimes transferred to the end-products. Gasoline from made from Lybian oil has less sulfur than that from Saudi oil.

Refineries are generally optimized to deal with a certain type of oil. Re-equipping one is complicated and expensive.

Availability is another issue. Transport issues mean that crude from the Middle East does NOT have the same price all over the world. Some places, it may simply be unavailable. When you see talk of "oil prices" on CNN, they are generally speaking of the WTI index, which is just that, an index value from a local market, describing the price of a notional barrel of oil of a given known quality. WTI crude does not exist.

All physical deliveries are priced against a given index, with prices modified to reflect delivery date and quality of delivered product.

As for electricity, the constraints the grid imposes (huge transport losses, frequencies etc), plus the infinitesimal amounts of storage available, mean that price varies wildly across the "global market". In fact, there is no global electricity market, so it's not a commodity.

 

[zapperzero]

I speculate that most engineers would rather deal with a high temperature, low pressure system than a lower temperature, high pressure (153 atm for a light water PWR) system.

Reprocessing from the spent fuel of a U235 light water reactor produces Pu upon re-processing, not so for Th based LFTR (in significant amounts).

You speculate. You are also conveniently glossing over the corrosion issue.
What do you mean when you say a LFTR does not produce plutonium in significant amounts? It does. Separating it as it is being produced is trivial.

 

[mheslep]

You speculate. You are also conveniently glossing over the corrosion issue.

I only know my own preference as an engineer when given the choice: low pressure, high temp, even with high corrosiveness, over a high pressure steam system that must be contained in the event of failure.

What do you mean when you say a LFTR does not produce plutonium in significant amounts? It does.

The Pu production pathways are secondary and low probability in a Thorium reactor as opposed to primary in U235/U238. And yes, though any amount of Pu produced has to be addressed, in comparison to the load produced and stockpiled in dry casks daily by existing light water U235/U238 reactors, the amount of Pu produced per GW-day is not significant in Th reactors.

Th - U233 reactor
$$\mathrm{^{1}_{0}n}+{}_{\ 90}^{232}\mathrm{Th}\rightarrow {}_{\ 90}^{233} \mathrm{Th} \xrightarrow{\beta^-} {}_{\ 91}^{233}\mathrm{Pa} \xrightarrow{\beta^-} {}_{\ 92}^{233} \mathrm{U } +\ ^{1}_{0}n\ \longrightarrow \mathrm{fission}$$

U235/U238 Reactor
$$\mathrm{^{238}_{\ 92}U\ +\ ^{1}_{0}n\ \longrightarrow \ ^{239}_{\ 92}U\ \xrightarrow[23.5 \ min]{\beta^-} \ ^{239}_{\ 93}Np\ \xrightarrow[2.3565 \ d]{\beta^-} \ ^{239}_{\ 94}Pu}$$

The Pu path in a Th - U233 reactor is a rare event, requiring five neutron captures. Along the way fission is much more likely than capture (U233 90%,U235 85%) or the capture cross section is low (U236):

$$\mathrm{^{233}_{\ 92}U\ +\ ^{1}_{0}n\ \longrightarrow ^{234}_{\ 92}U\ +\ ^{1}_{0}n\ \longrightarrow ^{235}_{\ 92}U\ +\ ^{1}_{0}n\ \longrightarrow ^{236}_{\ 92}U\ +\ ^{1}_{0}n\ \longrightarrow \ ^{237}_{\ 93}NP\ +^{1}_{0}n\ \longrightarrow ^{238}_{\ 93}Np\ \xrightarrow{\beta^-} \ ^{238}_{\ 94}Pu}$$

Furthermore, unlike a solid fuel reactor, a liquid/molten reactor enables the possibility that the Np237 is continually removed, further shutting off the Pu pathway.

http://www-pub.iaea.org/mtcd/publications/pdf/te_1450_web.pdf

In 232Th–233U fuel cycle, much lesser quantity of plutonium and long-lived Minor Actinides (MA: Np,Am and Cm) are formed as compared to the 238U–239Pu fuel cycle, thereby minimizing toxicity and decay heat problems.

 

[zapperzero]

And yes, though any amount of Pu produced has to be addressed, in comparison to the load produced and stockpiled in dry casks daily by existing light water U235/U238 reactors, the amount of Pu produced per GW-day is not significant in Th reactors.The Pu path in a Th - U233 reactor is a rare event, requiring five neutron captures. Along the way fission is much more likely than capture (U233 90%,U235 85%) or the capture cross section is low (U236):

$$\mathrm{^{233}_{\ 92}U\ +\ ^{1}_{0}n\ \longrightarrow ^{234}_{\ 92}U\ +\ ^{1}_{0}n\ \longrightarrow ^{235}_{\ 92}U\ +\ ^{1}_{0}n\ \longrightarrow ^{236}_{\ 92}U\ +\ ^{1}_{0}n\ \longrightarrow \ ^{237}_{\ 93}NP\ +^{1}_{0}n\ \longrightarrow ^{238}_{\ 93}Np\ \xrightarrow{\beta^-} \ ^{238}_{\ 94}Pu}$$

Furthermore, unlike a solid fuel reactor, a liquid/molten reactor enables the possibility that the Np237 is continually removed, further shutting off the Pu pathway.

http://www-pub.iaea.org/mtcd/publications/pdf/te_1450_web.pdf

Citation right back atcha.

http://www.energystorm.us/Management_Of_Super_grade_Plutonium_In_Spent_Nuclear_Fuel-r49699.html

Says there plutonium is NOT an insignificant concern. Incidentally, the fuel-blanket design of EBR-II is the one the Indians are aiming for. I wonder why? No, actually I don't.

Don't want supergrade Plutonium? Well, I guess you could just separate U-235, make stupid boring simple A-bombs and call it a day. From what I can tell from your fancy equations, it self-accumulates in the fuel in far greater quantities than U-236, while U-234 to U-235 is a relatively high-probability event (100 barns thermal, 700 barns full-spectrum so again it matters a lot what reactor design you use).

 

[mheslep]

Citation right back atcha.

http://www.energystorm.us/Management_Of_Super_grade_Plutonium_In_Spent_Nuclear_Fuel-r49699.html

Says there plutonium is NOT an insignificant concern. Incidentally, the fuel-blanket design of EBR-II is the one the Indians are aiming for. I wonder why? No, actually I don't.

At the moment I'm only interested in the discussion of the month which began https://www.physicsforums.com/showpost.php?p=3294391&postcount=335": thorium based thermal reactors, and for which I've shown above plutonium is not significantly produced. The EBR mentioned in your reference is a highly enriched uranium fast spectrum breeder reactor; of course it produces plutonium.

Don't want supergrade Plutonium? Well, I guess you could just separate U-235, make stupid boring simple A-bombs and call it a day. From what I can tell from your fancy equations, it self-accumulates in the fuel in far greater quantities than U-236, while U-234 to U-235 is a relatively high-probability event (100 barns thermal, 700 barns full-spectrum so again it matters a lot what reactor design you use).

No, U-235 doesn't accumulate, in a reactor it primarily fissions, or decays, or becomes U236. And no 235 can not be chemically separated from the four other isotopes of Uranium. U233 is the primary fission fuel for this kind of reactor, and theoretically it could be used to make a weapon, though it appears extraordinarily difficult to do because of the gamma emissions from the inevitable U232 impurities and its decay chain.

 

[zapperzero]

Ok, thorium-based. Which design are we talking about, exactly? I'd hate to make the same mistake twice.

Your argument re chemical separation is a straw man. I never said it's possible with chemicals, just possible. Of course isotope separation is hard, but it's no harder or easier than it is for uranium obtained from other sources.

Now, for the accumulation. Take a thorium-based design of your choice. How much U-235 is there, per unit mass, in the fuel, after six months of operation? How much Pu-238?

 

[mheslep]

Ok, thorium-based. Which design are we talking about, exactly? I'd hate to make the same mistake twice.

Well some modern variant of the original Thorium molten salt reactor as built at Oak Ridge
http://en.wikipedia.org/wiki/Molten...tional_Laboratory_Molten_Salt_Breeder_Reactor

Your argument re chemical separation is a straw man. I never said it's possible with chemicals, just possible. Of course isotope separation is hard, but it's no harder or easier than it is for uranium obtained from other sources.

Now, for the accumulation. Take a thorium-based design of your choice. How much U-235 is there, per unit mass, in the fuel, after six months of operation? How much Pu-238?

Interesting question, let me crunch that one ...

 

[chrisbaird]

I don't think that's sappy at all. But, in the time it would take to design, license, and build a few nukers, (Add extra time to deal with the courts while every anti-nuke protester in the country trys to stop construction.) the photovoltaic industry could provide a better solution. As demand grows the technology improves and the cost comes down. Lots of good paying jobs are created. There's really no reason why there couldn't be 2 or 3 kilowatts of PV cells on 2 million roofs through the sun belt in just 2 years.
Just a thought.

If you do the math, solar energy is not viable on the large-scale. No matter how amazing your photovoltaics are, there is simply not enough solar energy incident on the surface of the US to run the country without bull-dozing large swaths of land. I think its crazy how some environmentalists love solar, but if it were to be implemented on a large scale would require the destruction of large amounts of wilderness.

 

[mheslep]

If you do the math, solar energy is not viable on the large-scale. No matter how amazing your photovoltaics are, there is simply not enough solar energy incident on the surface of the US to run the country without bull-dozing large swaths of land. I think its crazy how some environmentalists love solar, but if it were to be implemented on a large scale would require the destruction of large amounts of wilderness.

That's misinformation. Current technology 20% efficient PV could capture enough sunlight to power the entire US electrical load (~1000GWe capacity) with an PV area of ~30,000 sq km (100mi by 100mi). http://www.miller-mccune.com/business-economics/leasing-america-s-rooftops-for-solar-energy-3987/" That portion at least requires bull-dozing nothing at all.

The problem with solar PV power lies in the distribution of that power, how to store it for use when the sun's not available, and, most of all, cost in comparison to other sources. The problems do not include a lack of solar energy incident on US geography. Edit: See for example
http://www.landartgenerator.org/blagi/wp-content/uploads/2009/08/AreaRequired1000.jpg

 

[Ivan Seeking]

That's misinformation. Current technology 20% efficient PV could capture enough sunlight to power the entire US (~1000GWe capacity) with an PV area of ~30,000 sq km (100mi by 100mi). The problem lies in distribution of that power, how to store it for use when the sun's not available, and, most of all, cost in comparison to other sources. The problems do not include a lack of solar energy incident on US geography.

Given that it tends to be less centralized, it seems that distribution is less a problem for solar than nuclear power.