Is the nuclear renaissance dead yet?

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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Enginerd
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Post by Enginerd »

hanelyp wrote:A couple years ago I read an article about reprocessing nuclear fuel to extract mixed actinides. Apparently makes a perfectly good reactor fuel, if you have a reactor designed for it. The bulk of power reactors operating today can't use it.

As further advantage
- the extracted fuel is useless for a fission bomb.
- the fission fragments extracted have a far shorter hazardous lifetime than the actinides recycled as fuel.
- the vast majority of potential fission fuel of whatever variety is extracted, as opposed to throwing away most of the U238 as in other recycling methods.
Uranium Is So Last Century — Enter Thorium, the New Green Nuke

KitemanSA
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Post by KitemanSA »

IntLibber wrote:As for hard disk failures, thats what flashdrives are for. Disk drives are obsolete, its all solid state now.
Didn't you know? RAID now stands for Redundant Array of Independant (or Inexpensive) DRIVES. You can have RAID flashdrives too. :lol:

Axil
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Post by Axil »

A couple years ago I read an article about reprocessing nuclear fuel to extract mixed actinides. Apparently makes a perfectly good reactor fuel, if you have a reactor designed for it. The bulk of power reactors operating today can't use it.
The longer that spent light water reactor (LWR) fuel is stored and/or the higher the burnup it undergoes, the more difficult it is to use as a reactor fuel (or build a bomb with it).

In an LWR, a percentage of the plutonium (Pu) burns in a reactor but a complimentary percentage does not burn but absorbs another neutron to form another higher order Pu isotope down a Pu neutron absorption isotope series.

Image

In a high burnup LWR, a significant portion of the Pu in its spent nuclear fuel is Pu241. This has a relatively short half-life (11 years or so) and decays to Am241.

Unfortunately, Am241 is a rather poor fuel. So by letting the LWR waste age for decades, the waste loses much of its Pu241. Not only does the fissile value go down with time and/or burnup levels, but the fissile/fertile ratio of the plutonium also goes down. This makes the plutonium less useful as a reactor stand alone fuel.

There comes a time when adding more U235, an accelerator, or a fusion neutron source is required to burn this old degraded waste.

rjaypeters
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Let's Have a Field Trip to Chernobyl!

Post by rjaypeters »

Tom Ligon wrote:Not that a bad reactor accident can't be really bad. Chernobyl was pretty horrific.
http://www.breitbart.com/article.php?id ... _article=1

Have to be careful, though. Look at the bottom of the article for claims of human casualties.
"Aqaba! By Land!" T. E. Lawrence

R. Peters

icarus
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Post by icarus »

Kiteman:
I would suspect that the folks around there are a tad HEALTHIER that others.
If you consider your children having plutonium in their teeth healthy then you are confirmed as completely nuts.

KitemanSA
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Post by KitemanSA »

icarus wrote:Kiteman:
I would suspect that the folks around there are a tad HEALTHIER that others.
If you consider your children having plutonium in their teeth healthy then you are confirmed as completely nuts.
Show me the data. I've seen scare tactics from governmental and non-governmental sources alike, but no hard data from either.

It is possible that folks immediately around the plant on that unluck day got enough exposure to climb into the ill-effects region. But statements of millions of people dead have not been born out to the best of my knowledge. If you have hard data to prove me wrong, please present it.

And truthfully, I kind of doubt either of us know what the real toxicity curve is for Plutonium in teeth. So I have no idea how healthful or NON-healthful it might be. Again, data? No, I am not interested in doing an internet search for such data as there are a plethera of data but little by way of reliable data without a great amount of cross checking.

Soylent
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Post by Soylent »

KitemanSA wrote:As long as you DON'T separate out the Plutonium!
Plutonium from spent LWR fuel is pretty useless to any serious, state actor wishing to have nuclear weapons.

The isotope you want is Pu-239. It is fissile with a large cross section, it undergoes only 0.02 spontaneous fissions per second per kg and it puts out only 1.9 W/kg from decay heat.

Spent LWR fuel also contains Pu-238, Pu-240, Pu-241 and Pu-242. All of these isotopes have some combination of problems ranging from not being fissile, producing a lot of decay heat or producing a lot of neutrons from spontaneous fission.

If there's too much decay heat you have to remove it with some form of radial heat sink while still managing to create a spherical implosion.

If there are more non-fissile isotopes you have to compensate by having a bigger pit which takes more explosives to compress, and keeping the pit compressed for longer due to the increased mean path before fission; which takes even more explosives. The weapon will be bigger and harder to deliver.

Neutrons from spontaneous fission cause the yield to become very uncertain. Depending on if there happens to be a bunch of neutrons around to start the chain reaction early or not the yield will vary from hundreds of tonnes of TNT to tens of kilotonnes of TNT.

When governments can build centrifuges or a big, dumb lump of graphite like the X-10 reactor designed and built for the Manhattan project in under a year, why would they bother with LWRs? And indeed, no one has ever bothered to go that route.

D Tibbets
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Post by D Tibbets »

Soylant, what method has N. Korea used. I thought that their first test was a fizzle, possibly because of contaminating plutonium isotopes.

Dan Tibbets
To error is human... and I'm very human.

Enginerd
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Post by Enginerd »

D Tibbets wrote:Soylant, what method has N. Korea used. I thought that their first test was a fizzle, possibly because of contaminating plutonium isotopes.
They may very well have simply loaded up a bunch of Ammonium nitrate + fuel oil, set it off, and claimed it was a nuke...

icarus
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Post by icarus »

Show me the data.
googling "sellafield plutonium teeth" shouldn't be that difficult for a maestro like yourself? It's all out there, unless you don't want to see it?

http://en.wikipedia.org/wiki/Sellafield
A 1997 Ministry of Health report stated that children living close to Sellafield had twice as much plutonium in their teeth as children living more than 100 miles away.
I'm not saying it is necessarily a bad thing but how much Plutonium would you be comfortable with in your kids teeth Kiteman the ingenious?

Or perhaps you would like to show me the data for a safe level?

olivier
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Location: Cherbourg, France

Post by olivier »

I found many interesting things in the discussion. Here are my two cents.
Nuclear Waste:
Found in Theodore Rockwell’s Nuclear Energy Facts Report:
The radioactivity of the used fuel decreases, until after 300 to 600 years, it approaches the level of the ore from whence it came.
This is grossly wrong. As often proponents and opponents oversimplify allowing endless polemics to take place and confusion to spread in the public.
  • It takes over 250,000 years for the radioactivity of used fuel to approach the level of uranium ore. If you went that far back in time, Homo Sapiens would not be on the surface of Earth.
    Plutonium is the main contributor to the radiotoxicity of the waste. If, by reprocessing the waste, you remove plutonium and uranium and burn them, it takes 10,000 years to reach the level of ore. Still back to prehistoric times, but a big leap forward indeed.
    The second contributor are the minor actinides. If you remove them (this is done neither in La Hague, Sellafield or Rokkasho Mura), it only takes 250 years back to ore level. Back to the Age of Enlightenment. Sounds good.
My personal conclusion is that burner reactors make a lot of sense and that we ought to build them or let go of nuclear energy. Are we ready to make that effort? The problem is that our free-market economy, which does not even care for our children, totally disregards such long term issues. Other economic models might do even worse for several reasons.
Vitrification:
Icarus wrote:THORP was designed to have most of recoverable waste going into the MOX plant for new fuel and the rest to vitrification. Kind of got going but hasn't quite worked out as planned, it never does ... govt. sponsored nuclear reprocessing is a quagmire of contractor vested interests, incompetent bureaucracy, paranoid officialdom and bleeding-edge engineering.
The British disaffection with their nuclear industry may be the origin of all the problems Icarus mentioned. No industry is immune to a long disinvestment.
I worked for La Hague for quite a couple of years and, though I am more power plant oriented today, I still live 15 miles from the plant. It is a fact that what has not worked yet in Sellafield's THORP plant works pretty well here, including the latest cold crucible process.
One may consider it is a better option to leave spent fuel for future generations to reprocess with better technology, one is free to criticize vitrification for its cost or because one’s religion forbides it, but nobody can deny vitrification is feasible at an industrial scale.
Americium:
Axil wrote:So by letting the LWR waste age for decades, the waste loses much of its Pu241. Not only does the fissile value go down with time and/or burnup levels, but the fissile/fertile ratio of the plutonium also goes down. This makes the plutonium less useful as a reactor stand alone fuel.
This is definitely true but removing americium from plutonium is no big deal. La Hague has a plutonium redissolution unit which allows old plutonium to reenter the separation process where it is de-americized (hard to pronounce). This is important if you plan to use the plutonium in MOX fuel. Less important if you focus on decreasing the radiotoxicity of the waste in a burner.
Non-proliferation and reprocessing:
KitemanSA wrote:Most of the rest of the world follows suit except the two main Old Communist countries (USSR and China) and of course the socialist and contrarian French :lol:
You forgot to mention the feudal Japanese, the rebellious Indians, and the capitalist and complacent British... :lol:
All countries with the notable exception of India, Pakistan and Israel signed the Non-Proliferation Treaty. This treaty allows those nations who already had the bomb to keep their military activity (US, USSR, China, UK and France). The idea was just not to extend the club. It did not ban reprocessing for peaceful uses but put it under scrutiny of international safeguards. To my knowledge, the ban of reprocessing in the US results from a US policy. Maybe you could appeal to the 2nd Amendment to have this changed. ;-)

Plutonium in teeth:

It sounds very unpleasant but what are the figures? I would be interested in more information. In its early era, the nuclear industry was not as clean as it is now and it may have consequences in the present. Just like Chernobyl has.
I know of several epidemiologic studies about leukaemia occurrence among very young children, but they are dealing with very small numbers below statistical significance (figures like 5 cases in a population of 100,000 were the average should be 3).
In any case, please avoid Doramad toothpaste. Sorry for making fun out of something serious but I could not help.

jsbiff
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Post by jsbiff »

olivier wrote:This is grossly wrong. As often proponents and opponents oversimplify allowing endless polemics to take place and confusion to spread in the public.
  • It takes over 250,000 years for the radioactivity of used fuel to approach the level of uranium ore. If you went that far back in time, Homo Sapiens would not be on the surface of Earth.
    Plutonium is the main contributor to the radiotoxicity of the waste. If, by reprocessing the waste, you remove plutonium and uranium and burn them, it takes 10,000 years to reach the level of ore. Still back to prehistoric times, but a big leap forward indeed.
    The second contributor are the minor actinides. If you remove them (this is done neither in La Hague, Sellafield or Rokkasho Mura), it only takes 250 years back to ore level. Back to the Age of Enlightenment. Sounds good.
I have a question - it's my understanding that radioactivity decreases according to the 1/2-life principle - e.g. every X years, 1/2 the quantity of a particular element will decay, meaning it becomes 1/2 as radiactive (ok, let me clarify - the lump of mixed nuclear waste won't be 1/2 as radioactive, necessarily, because it has different elements with different 1/2 lives, but the amount of radioactivity due to a *particular* element is halved according to that element's 1/2-life. So far so good?)

after 1 half-life, that element is 1/2 as radioactive, after two, 1/4, and more generally, after n half-lives, it is 1/(2^n) as radioactive, right?

Now, that 250,000 year figure - how many 1/2 lives is that for that element, and how radioactive is that element? I would think that after 7 to10 1/2-lives, even the most obnoxiously radioactive elements would be pretty 'safe' (7 half-lives corresponds to having 1/128 the radioactivity, meaning slightly less than 1 percent, but I suppose for the most active stuff, even 1 percent might be dangerous, but 10 1/2-lives corresponds to 1/1024 the radioactivity.

Since a 1/2-life decay model starts out decaying rapidly, but then slows down a lot (well, it keeps halving, but in absolute magnitude, the decreases rapidly drop off), the behavior is that it asymptotically approaches zero, but never quite gets there. So, is the dispute between what you are saying and what the Nuc. Facts Report is saying just a matter that Ted Rockwell is, perhaps, saying that after 300-600 years, enough of the elements have had their first few 1/2-lives that the radioactivity has dropped down to something like 2x background, but your figures are focusing on the fact that once it gets there, it stays between background and 2x background for another 240,300 years because of that asymptotic behavior?
My personal conclusion is that burner reactors make a lot of sense and that we ought to build them or let go of nuclear energy.
Here, here! Wholeheartedly concur - I'd like to see a phase out of LWRs and start seeing deployment of fast breeder reactors like the IFR/PRISM. We need to start burning up the waste, poste-haste. I like the idea of waste which only needs to be contained for 200-500 years - I firmly believe we have the know-how to do that (things like vitrification, then sealing in casks, then putting inside geologically stable repositories underground like Yucca mountain or similar).
Are we ready to make that effort? The problem is that our free-market economy, which does not even care for our children, totally disregards such long term issues. Other economic models might do even worse for several reasons.
As you might have gathered, even though I'm not a nuclear engineer, physicist, whatever, I've been doing a LOT of reading to try to get answers to a lot of questions I have about nuclear, over the past year, and especially this past month.

A few of the lingering questions in my mind, which I've been trying to answer the past few days, resolve around the economics of nuclear: Why are nuclear plants so expensive? Why isn't there private funding available? Nukes might cost a couple Billion to build, but there is a LOT of private money out there - the Forbes 10 richest Americans have a combined net worth of something like 1.3 Trillion dollars, and that's just the 10 richest, so it seems like we shouldn't need to go to the government to get nukes built, right?

So, I found a few articles.

One in particular was very enlightening:

http://www.phyast.pitt.edu/~blc/book/chapter9.html

That's a chapter from a book titled, "The Nuclear Energy Option" by a pitt.edu professor (emeritus).

The nutshell version of what I've been finding so far is that the main drivers for the increase in costs for nuclear construction over the past 50 years have been:

* Lack of standardized reactor and plant designs - most plants were 'custom builds', which tremendously drives up the costs of construction, inspection, licensing, etc. Apparently other countries have adopted standardized designs, and managed to significantly reduce the build time/cost.

* Old reactor designs which were less safe (though as we've seen over the past 50 years, still pretty safe), but which pushed the physical limits of reactor design to get the maximum efficiency/power output. New reactor designs have been designed to be simpler, safer, and cheaper at the 'expense' of efficiency (although, arguably, Gen IV designs which recycle fuel, even if they waste more heat during electric generation due to lower thermodynamic efficiencies, because of the recycling, are far, far more efficient than once-through reactors without breeding/reprocessing the fuel - so who cares about that 'wasted' heat if you are getting 20-50 times more energy out of each ton of fuel). Getting back to my point, the old designs were initially cheaper to build, but once the nation got serious about safety, the NRC decided that a lot of very costly safety enhancements needed to be made to make those reactors safe (I think some argue, like the authro of that pitt.edu book, that some of the measures added to cost greatly while addingn to safety only minimally).

As for the other question - why lack of private capital for funding new construction:

From different sources, the answer(s) seem to be:

* Seeing costs greatly inflate *during the construction cycle*, meant that nuclear plants doubled or tripled their initial price. Nobody wants to be told that the thing they are buying costs X, then when it's delivered, be given a bill for 2X or 3X.

* Political climate was very uncertain - public opinion was rapidly changing about Nuclear power during the 80s and 90s, and even if you could get permission to start during 'this' administration (say the Reagan administration), there was no guarantee that the next congress or next president wouldn't make sweeping changes which would completely screw up your very large, long-term investment. This 'political risk' made private capitval view investments in nuclear power as very risky indeed - high stakes (Billions per plant) coupled with very high uncertainty means that investors find elsewhere to invest the funds.

So, it would seem the remedies to these problems are:

A) Smaller, safer, cheaper standardized reactors built and quality controlled in factories, installed into plants constructed according to standardized designs (or retrofitted to existing plants, e.g. the coal-to-nuclear concept).

B) Have some of these in operation for several decades *without* any incidents, so that the public becomes more confident in the 'new nukes'. This will stabilize the political climate.

Once A & B are done, investors will gradually come have the confidence in nuclear to put up the largish (though, hopefully the cheaper reactors will reduce the costs significantly from where they currently are) sums of private capital needed to start building again *without* government money.

olivier
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Post by olivier »

jsbiff wrote:I have a question
This page about will probably answer several of your questions the radiotoxicity of spent fuel, then raise other questions, which is the good approach to any field.
Although I am not a specialist in radiotoxicity, I hope I know where to stop before writing anything stupid.
The important thing about waste is toxicity, not radioactivity per se. The half-life does not say much about radiotoxicity.
As you know, an actinide may decay into several other actinides with alpha, beta, gamma or neutron emission at various energy levels. This is very different in terms of short or long term biological effect. This is why biological effects are measured in Sieverts rather than rads and grays. These actinides will themselves decay into..., and so on... It soon becomes complicated and the use of computer with an evolution code is strongly recommended.
Plutonium is the first contributor to the radiotoxicity of spent fuel. Second come the minor actinides, though they are in a very small quantity in the fuel.
The half-life of plutonium 239 is 24,000 years. It is not very radioactive but it is a strong alpha emitter: it will not do you too much harm at the surface of your skin but it is very toxic when ingested because it will stay in your body and destroy your cells for a long time.
If you have 5 kg of plutonium in a spent fuel assembly, then after 250,000 years you have 5 g. Not that much, but more than traces.
So, is the dispute between what you are saying and what the Nuc. Facts Report is saying just a matter that Ted Rockwell is, perhaps, saying that after 300-600 years, enough of the elements have had their first few 1/2-lives that the radioactivity has dropped down to something like 2x background, but your figures are focusing on the fact that once it gets there, it stays between background and 2x background for another 240,300 years because of that asymptotic behavior?
I understand your comment. Look at the curve and decide which level is acceptable to you. You have to choose a reference and the usual reference is uranium ore which btw is not something I would store in my backyard. What decreases drastically after 600 years are the fission products, not the plutonium. 600 year old spent fuel is still very dangerous.

KitemanSA
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Post by KitemanSA »

icarus wrote:
Show me the data.
A 1997 Ministry of Health report stated that children living close to Sellafield had twice as much plutonium in their teeth as children living more than 100 miles away.
I'm not saying it is necessarily a bad thing but how much Plutonium would you be comfortable with in your kids teeth Kiteman the ingenious?

Or perhaps you would like to show me the data for a safe level?
Re how much, I do not know. But what I am pretty dang sure of is that it is not a Linear-Thru-Zero (LTZ) curve which is what the government uses as a toxicity model for anything radioactive. As a result there are REDICULOUS claims made as to probable results from nuclear incidents, and thus FEAR runs rampant.

If I were a conspiricist, I might even believe that said fear and its resultant lack of nuclear power, is the intent.

Re show me: it has been a while, but IIRC, the background radiation in rural Minnisota is substantially higher than the background radiation in "all else being equal" rural Iowa, yet the incidence of those diseases one typically associates with radiation (cancer, etc.) is LOWER in Minnisota than Iowa. At least that was the data presented in that article I read way back when. If the government's "linear-thru-zero" toxicity curve were correct, that would NOT be the case. This suggests that at a low enough level, radiation is BENEFICIAL to one's health. This condition is known as "hormesis". What the REAL radio-toxicity curve is, I don't know. But I do state categorically that any statements by government that have the potential to scare a goodly number of people and are based on curves like the LTZ curve are GROSSLY, even criminally irresponsible.

Soylent
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Joined: Sat Jan 03, 2009 9:23 pm

Post by Soylent »

D Tibbets wrote:Soylant, what method has N. Korea used. I thought that their first test was a fizzle, possibly because of contaminating plutonium isotopes.

Dan Tibbets
North Korea used a heavy water moderated IRT-2000 research reactor to get sample amounts of plutonium to play with(not enough for a bomb) and a graphite-moderated Magnox reactor fueled by natural(unenriched) uranium to produce the plutonium in weapons-usable amounts.

The Magnox reactor was developed principally to produce weaponsgrade plutonium; the large amounts of waste heat was seen as a useful byproduct and used for district heating and electricity. Magnox reactors later achieved much higher burn-ups, making them more useful as power stations(when operated with higher burn-ups their plutonium is less suitable and not used for weapons).

These other isotopes of plutonium are primarily a function of burn-up. Production of Pu-239 and its precursor Np-239 starts immediately as the fuel is put into the reactor because it only takes one neutron capture in U-238 to make it. Pu-238 takes 3 neutron captures from U-235 and Pu-240, Pu-241, Pu-242 take 1,2 and 3 neutron captures from Pu-239. Pu-239 has a head-start if you will, these other isotopes take a while to start being made.

What makes graphite moderated reactors so outstanding for weaponsgrade plutonium production is that it can be fueled by unenriched, natural uranium without any need for enrichment; which is a complicated technological and engineering task. Because of the need for frequent refueling most of them have online refueling(don't have to turn the reactor off in order to change fuel elements).

The X-10 graphite reactor, a Manhattan project plutonium producer, was simply a glorified graphite block with channels drilled into it and some concrete acting as a neutron shield surrounding it. Into the front-face workers would shove slugs of natural uranium and spacers with a pole. As they did so spent fuel slugs would fall out the back of the reactor and into a water bath, waiting for Np-239 to decay into Pu-239 before being reprocessed. A slight overpressure was maintained in the building so that short-lived fission product gases(notably xenon-135, xenon-137 and krypton-90) that escape from the surface of the fuel slugs do not come back out the front-face of the reactor. In a slightly less archaic reactor, like a Magnox, the fuel is inside cladding and any gas that escapes from the surface of the fuel pellets/slugs is trapped until it decays or capture a neutron(Xe-135 has an enormous neutron capture cross-section, which vexed early reactor designers).

If you were to operate an LWR in order to produce weaponsgrade plutonium you would have to shut the reactor down every few months or so and begin the time consuming procedure of replacing the fuel. This weird pattern of very frequent refueling is easily seen from satellite(e.g. vapour from the cooling towers, fuel shipments, spent fuel shipments), and inspectors don't take kindly to unexplained starts and stops. If you can enrich your own fuel you can enrich your own weaponsgrade uranium and you don't need the plutonium(although plutonium is a bit better for miniaturized warheads); if you can't enrich uranium and you're deseperate enough to try and use an LWR for producing weaponsgrade plutonium the people who are supplying you fuel are going to want a reasonable explanation for why need so much fuel and they may require that you return all the spent fuel(as Russia intends to do with spent fuel from Bushehr).

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