Electric cars are a pipe dream

Well, CANDU reactors can operate with plain old uranium (i.e. mostly U-238.) No enrichment required. And there's a lot of that - and if you can't enrich you can't make bombs.

Thorium reactors are a good idea too, but we can't build them yet due to the lack of a good proton source. (Thorium reactors cannot start fission on their own.) The alternative is a uranium/plutonium core to start the thorium reaction, but then you're back to the same old problems. Thorium reactors also produce a lot of hard gamma radiation, which means that even the shielding becomes quite radioactive over time.

 

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I am not sure, but think the CANDU reactor only "burns" U235, not U238. They use heavy water as the moderator (to slow the fission neutrons down / in crease the capture cross section in U235) and are more "neutron efficient" that other reactors moderators, so there is no need to enrich the percentage of U235. - Please correct my memory if wrong - it been a long time since I read about the CANDU reactors. Note their heavy water has DeUterium, Du, and they were invented in Canada - hence the name.)

While it is possible to keep thorium fission reactor going with high energy particle beam, that is not how it is done now. Instead a small amount of spontaneously decaying with neutron release U233 is added, initially, to bring useful neutron absorption and release rate ratio to unity. As the thorium reactions runs alpha particle are released which when absorbed in other thorium atoms convert them to U233.

I.e. with proper design you can breed the U233 at the rate it is decaying so the only fuel needed is thorium. Even getting the initial start up charge of U233 takes much less "separation work units" as the mass difference from U238 is 5 not just 3 when U235 enrichment is needed.

It think the U235 enrichment is only needed to increase the probability that a neutron will hit another U235 atom before it is lost to the outside world or absorbed in something else. Submarine reactors are much smaller than electric power reactors so a greater fraction of the neutrons do escape to the "outside world." Hence the percentage enrichment required for a nuclear submarine reactor is greater than for an electric power reactor.

This is also why fuel rods in a conventionally moderated reactor are removed from reactors when only 5% of the U235 has been "burned" - i.e. with the probability of hitting a U235 atom reduced to only 0.95 of what a new fuel rod gives, the chain reaction goes out or is very slow.
Again please correct any errors - I am working mainly from memory.

I am almost sure that there is LESS radiation release by a thorium reactor than a uranium reactor so LESS shielding is required. Certainly the gamma rays released do not cause ANY shielding material to be come radioactive. - You can not induce radioactivity with gamma rays! That takes high energy particles if charged or neutrons, AFAIK. A gamma ray could excite a nucleus to an excited state from which it could decay with the release of essentially the same energy gamma ray, now traveling in a new direction.

 

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Yes, it just works with raw uranium (i.e. with the small percentage of U235 found in natural uranium.) The big difference is that no enrichment is required, so the fuel becomes MUCH cheaper, more available and is proliferation-resistant.

Yes, current designs use a core, or a "seed" of carefully processed fissile isotopes to start the reaction. This works well but negates some of the benefits you get from not having to separate isotopes of uranium.

To get around this, the "energy amplifier" (thorium core + proton source) has been proposed. This uses a very high power particle beam to generate thermal neutrons; these cause fission, releasing energy above unity. This fission reaction then breeds U-233 which helps continue power production.

One benefit AND drawback of this is that a very high power proton source is required for the reaction to occur. This is bad due to the cost and complexity of the source; good because a failure of the source (due to, say, an earthquake) shuts down the reactor almost instantly. However, decay heat still has to be removed for a short time.

Hmm, from what I've seen the energy contained in the hard gamma ray spectrum from the decay products of thorium fission is a lot harder to shield than the gamma ray energy produced during U-235 fission. Can't find the energy numbers right now though.

Agreed; sorry, I didn't mean to imply that the gamma radiation is 'breeding' isotopes in the shielding.

 

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Yes, but it does not use the 99+ percent of the the raw uranium that is U238.

My memory was correct CANDU does NOT burn U238:

“… Uranium-238 is the most common isotope of uranium found in nature. It is not fissile, but is a fertile material: it can capture a slow neutron and after two beta decays become fissile plutonium-239. 238U is fissionable by fast neutrons, but cannot support a chain reaction because inelastic scattering reduces neutron energy below the range where fast fission is probable. …”

From: http://en.wikipedia.org/wiki/Uranium-238

You don’t seem to understand the basic advantage of the CANDU reactor. That is its greater neutron utilization efficiency. Like all other uranium reactors it only “burns” U235, but the concentration of U235 can be significantly lower in the fuel rods – less than the natural U235 fraction so no enrichment is needed.

Perhaps a good idea is to run a CANDU reactor next to a conventional reactor which only can burn about 5% U235 in the more enriched fuel rods. Then when they must be removed, instead of just storing them in a pool, put them into the CANDU reactor which can operate with less than 1% U235 concentration.

As the thorium reactor can generate all the U233 it needs to keep running right in the liquid core as it runs, the separation of a little U233 from natural uranium or spent fuel rods for start up is a ONE TIME cost and not very significant compared to making and continuously operating a high energy proton beam source.

It is much like the CANDU's one time separation cost. The DOH must be nearly pure and is separated from HOH, but a much larger volume of DOH is required than the start up only volume of U233. Thus it is quite misleading to fault the Thorium reactor because it does have isotopic separation required. The CANDU isotopic separation cost I would guess is 10 times greater, but both are only "one time costs."

Even worse if the CANDU uses DOD instead of DOH - my memory is not clear on this. Perhaps as it runs it converts some DOH into DOD?

 

Naturally occurring Uranium has a 0.72% concentration of U-235 in it already, so it appears you are both right.

Billv is right that there is no need to enrich it (because it's already got enough U-235 when it is first mined). And you are certainly right that the U-238 is not what is getting burned.

http://en.wikipedia.org/wiki/Uranium-235

.. but I think perhaps your point was that a breeder reaction could be used to to change some of the U-238 into U-235 or Plutonium before it goes into the CANDU system, so there will be more total fissile material present? Do I understand you right on that?

http://en.wikipedia.org/wiki/Breeder_reactor

 

HAHAHAHA . . .HA.

Efficient
1.
performing or functioning in the best possible manner with the least waste of time and effort: (OIL).

Producing more dollars per barrel of oil IS a measure of efficiency.

Adoucette:

I think you are confusing PRODUCTIVITY with EFFICIENCY. Big LOL. Simply using loads more oil to produce more GDP (less efficiently)says nothing for efficiency.

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No it is not.

You put OIL into the definition as the equivilent of time and effort, but OIL is not the equivilent of time and effort, it is also a raw material and if you are the world's LARGEST MANUFACTURING ECONOMY (Last year, the US created 20% of world manufacturing output), you will use more oil then say a service based economy like the UK.

Note that China is coming up fast on the US, but then it's oil use is soaring as well.

Then there is the fact that we also use oil because we can afford to do so, you know as driving bigger cars, towing campers and trailers, going on long vacations etc. but our recreational use of oil has nothing to do with how efficient we are in making high GDP per capita, indeed, it is this high GDP per capita that allows us to use oil for recreational uses and not sweat it.

Then there is the fact that we enjoy a more highly Suburban lifestyle then most countries which of course involves more daily driving, particularly by Soccor Moms running their kids to various events, but this as well is a choice and not related to any efficiency of producing GDP per capita.

Get over it.

Arthur

 

Me? get over what? Americans are the ones who are wasteful. LOL.

So let me get this straight. You think that oil doesn't supply energy, which supplies mechanical energy/effort. Who are you to say that the effort of machines, or humans via the multiplication of machines is of no importance here.

Humans run on fuel too, and Americans eat too much of that too (excess, look at US obesity). LOL.

My use of the term efficient is not something you can question lol. Fail. BIG Fail.

 

Of course oil supplies energy, but it is also a raw material used in making lots of products and a huge amout of the oil we consume goes into making products and even paving our roads (about 20%).

It's also used recreationally, so you can't say we are inefficent based on how much oil we use per $ of GDP because every section of the manufacturing economy uses oil to different degrees and plenty of oil is used in ways that is not at all related to our GDP.

For instance we use oil in recreation, Jet fuel for taking trips and for our Boats and ATVs and RVs and GA aviation fleet, and their use of oil is not related to our GDP.

So if you wanted to compare the efficiency say of our pounds of plastic production per barrel of oil with Japan's then that would be a valid comparison, but your simplistic method means nothing.

Actually it is, and in fact you can't provide a single generally accepted definition of overall efficiency that says that the ratio of GDP to Oil use is a valid measure of a nation's efficiency.

Indeed you already admitted that you couldn't compare the US Manufacturing based Economy to the UK's before:

So you have already admitted that the economies are not the same and that you run a SERVICE based economy, which of course is far less oil intensive per $ of GDP then one that makes 20% of the products made in the world today.

All that comes out is your lame attempt, once again, to attack Americans.

Face it.

You're a BIGOT.

Arthur

 

The word 'efficient' has a wide range of definitions.

My country, New Zealand, is very efficient in its agriculture. However, that is financial efficiency. It means we produce a lot of agricultural products per dollar invested, compared to most other countries.

Iceland, however, is probably the most efficient country on Earth in terms of agricultural land area productivity. That is because they grow food in geothermally heated greenhouses, and grow it hydroponically, so they produce lots per acre, though at a high financial cost.

Both New Zealand and Iceland have very efficient agriculture, but using different definitions of 'efficient'.

The same applies to efficiency in use of oil. Depends how you define your terms.

 

No. You are deluded dumbass. Americans are wasters, literally. Get over it. wasteful leisure activities just compounds the truth of the ignorance of your nation. Obese bunch that you are. The fact our government chooses to forge an economy that runs on less resources is a credit to us. The fact the US are over consumers in virtually everyway you can possibly imagine is of no regard in your obese-stanced mind.

You are a ignoramus.

If you really believe that GDP per barrel of oil is of no importance then once again you highlight the possible futility of trying to tackle global warming. This issue must be addressed, and GDP per barrel of oil in america increased. I say increase fuel tax up to european levels. That'll sort you lot out.

I live near Lakenheath airforce base. That is in the UK. All the americans around here drive oversize cars. What is their excuse dumbass? Their only excuse is that they can buy fuel on base at US prices. If that wasn't enough they container over their piece of shit gas-guzzlers from the US. JEEZUUZ. What a waste. But I guess they cab afford it so that's OK. Explain that one???

Roll on the EVs I say. When people with your attitude are predominantly dead and buried the world will finally be able to tackle thse issues head-on.

 

So in your idea of a world we can't have recreational vehicles?
We can't have jet skis, ski boats or ride our hogs on the open road with wind in our hair for fun?

Well fuck that.
If that's your idea of living a good life then no wonder the sun set on your empire.

Live free I say!

It's the pursuit of happiness and the money that allows you to do those things that gives us lesiure time, Iphones and Kindles and Boeing jets.

Life is also about having FUN, about making enough extra money and having enough free time to learn how to pilot an airplane just for the sake of flying like a bird or exploring the country in your RV or racing across a glass like lake in search of a lunker bass, or turning up the burners on your hot air balloon and filling the sky with their enormous shapes.

We have no intention of giving up having fun, and few fun things don't require using energy, sometimes prodigous amounts, like when you hear the throaty roar of the big V twin engine and the kick in your back when you twist the throttle and if you can't get behind the life affirming exhileration of that kind of raw power between your legs then just bugger off and play with your dolls with the other sissies.

What BS from the man who admits that you are no longer a manufacturing nation and rely on other countries, who have to use far more barrels of oil per $ of GDP then your wimpy Service based economy, to make the basic things that you can no longer make yourself, and then are so hypocritical as to complain that the nations that make the very things you absolutely need to get by on must use oil to do so.

Truely pathetic.

As to global warming, I already explained it to you.

Pay attention.

China is the world's largest emitter of CO2 and the developing world is increasing it's CO2 production per capita every year while the US is reducing their contribution, even with an expanding population.

More to the point, even if the US cut their gasoline use in half it would have no virtually no impact on CO2 levels because of the growth of the world's population (heading to 9 billion at the middle of this century) so take all your hand wringing about CO2 emissions and explain it to the Chinese because frankly there is nothing we (or you) can really do about it.

If the US doubled the miles per gallon they got in their cars it would reduce global CO2 emissions by about 2 percent, which is equivilent to just a few years CO2 growth, in other words, it would have virtually no impact at all.

In the mean time, the US is the largest producer of nuclear energy and the largest single producer of wind power, so you can talk when you come close to the amount of renewable energy we produce.

Arthur

 

While 'France' does reprocess its fuel, France doesn't do it. That is, France (or, more properly, certain French people involved in the French nuclear industry) ships the rods to Japan for reprocessing, because it was too politically difficult to do it in France. After Japan (those certain people involved in the Japanese located reprocessing industry) reprocesses it, they ship it back to France. These are usually secret shipments by commercial ships, so we don't hear much about it.

 

Plenty of leisure pursuits other than burning copius amounts of fossil fuel. LOL.

 

Yup, and there are plenty that use fossil fuel.

So here's the question:

Do you think that fossil fuel shouldn't be used just for fun?

Should we ban recreational vehicles?
Recreational boating?
Recreational aviation?
Not allow them to make big RVs?

Well?

 

Hopefully scientists will figure a way around before we need to dent your valuable leisure time.

 

So you didn't actually answer the question.

Yes or No.

Is it ok to burn fossil fuel for purely recreational use?

 

Your question is simple. Your agenda within the question is simple. The answer is complex.

The fact you present the possibility you do not know the answer points to your delusion.

 

Deluded about what exactly?

And if you say the question is complex and you can't answer the question with a simple Yes or No, then you can always provide a more complex answer.

No one is stopping you, but you.

 

I have espoused my stance over and over in this thread.

The world is in transition from fossil fuels to alternative energies. We are along for the compromise of the ride. Does that answer your question? It'll have to cos that's it.