It's the pebble-bed reactor discussion thread....

[phantom power]

So, I'm reading this article in Wired magazine about pebble-bed reactors, and they're talking about how this idea was proposed way back in the era of the Manhattan project. But the Navy threw a bunch of funding behind fuel-rod based reactors for nuclear subs, and the rest is history.

We could have had safer, cheaper reactors all along, but we went down the wrong road.

The space shuttle versus the X-programs.
Urban sprawl versus mass-transit.
Microsoft versus Macintosh.
Betamax versus VHS.

For the love of all that's holy, do we *ever* make the right technology choices???

Maybe this is also the "stupid technology choices" thread. But mostly I still want it to be the pebble-bed reactor thread.

[benburch]

1. I'm not sure it would have been remarkably safer.

You see, until we build a large number of these reactors, and find out all of the problems that Murphy's law has to reveal, we don't have a clue as to whether they would really be safer in practice...

[phantom power]

2. The chinese have a working model, and it really is safer

The fuel pellets are specifically designed to exhibit homeostatic behavior: the hotter they get, the fewer neutrons they absorb. The reaction can't run out of control.

The chinese have actually tested this property, by shutting down the heat exchanging circulation. The reactor started to heat up, and then cooled down.

I read another article a couple years ago that said some engineers were concerned that the pellet-substrate could burn if it got too hot, and if it came in contact with oxygen. I don't know if they changed materials, or if the fuel design prevents it from getting that hot. Or, maybe it's still a risk.

Anyway, there isn't the problem of having to always worry about the coolant circulation, like there is in a traditional reactor.

[DODI]

3. Money seems to be getting in the way of the furthering of the pebble bed

As I recall, Westinghouse was going to build one in South Africa, but then the South African gov't pulled its financing. I would not be surprised to see this start up again with the high cost of oil in SA.

I just found an article from Business Day regarding SA involvement with the pebble bed and they are working with BNFL on going forward (BNFL is Westinghouse's parent company)

http://www.bday.co.za/bday/content/direct/1,3523,1684926-6078-0,00.html

[NNadir]

4. These reactors are designed to be cheap to build and modular,

but I'm not sure that they're the right choice.

I happen to think that the PWR (Pressurized Water Reactor, the submarine design) has been one of the most successful energy system designs in history. Only one has failed (Three Mile Island) and even this failure, although dramatic in economic terms, was hardly catastrophic to the environment. In the meantime they have provided enormous amounts of energy with a record of safety, cleanliness and minimal environmental impact that is better than any other large scale energy production technology available.

The Pebble Bed reactor has some advantages that may make it ideal for some applications, particularly those requiring high temperatures, but it has an important limitation in that the design is intended to be "once through." The pebbles are designed to be stable for millions of years, and therefore are not amenable to reprocessing. This might fit the bill in the mentality of the early twenty-first century, but it may look rather short-sighted and a little selfish to future generations. I believe strongly that future generations will need not only the unspent fuel, but many of the fission products as well, in particular the precious metals like Palladium, Rhodium, and Ruthenium.

There is one area of nuclear technology where a very poor choice of technology was, in my opinion, made. This was the selection of Liquid Metal Fast Breeder Reactors (LMFBR) over molten salt reactors.

In any case, nuclear technology as it develops in the next century, as it must if we are to survive, is not either/or. We will need several major types of reactor design as we seek to balance the goals of safety, sustainability, productivity, "waste" management and nuclear disarmament.

Here are my three favorite types of reactors:

1) Pressurized Water Reactors.

2) Candu (Heavy Water) reactors.

3) Molten Salt Reactors.

I think the other types have some applications, notably High Temperature Gas Cooled Reactors, to which pebble bed reactors are related. One reactor for which there is zero need is the graphite moderated of the Handford/RBMK/Windscale Type, which have famously proved to be disasters of the worst sort. This latter type of reactor should never be built again and those that exist should be shut down as soon as is possible. These reactors were primarily built with military applications in mind.

[phantom power]

5. what is your take on shielding requiremenst?

Another feature (claimed) of pebble-bed reactors is that they require less shielding, which also contributes to their lower cost.

Regarding the recovery of fission products, is it the case that it's hard to separate the byproducts from the pebble substrate?

[NNadir]

8. I can't, off the top of my head, think of any particular shielding

benefits, though there might be some advantage of which I'm unaware.

Shielding, of course, depends on the use of heavy elements, and, of the naturally occurring elements, Uranium is the heaviest. This means that by definition, nuclear reactors are self shielding to an appreciable extent. (Note: Fusion reactors aren't.) This is why one can safely operate a nuclear reactor in a small confined space like a submarine.

Fuel management, which accounts for much of the improvement in nuclear reactor performance in the last decades plays a role here. One of the more intriguing developments to my mind is a fuel loading scheme known as the Radowsky configuration, in which the outer core fuel elements are the heavy element and fertile fuel Thorium.

As for the second matter, long term stability is always opposed to ease of separation. This is another reason I'm unhappy about the proposed facility at Yucca Mountain. The waste form is too stable and it's going to make big problems for the folks that want to get that stuff out in the future.

[phantom power]

12. Maybe I'm using the wrong term.

I was thinking of containment domes. Supposedly, these pebble-bed reactors don't need containment domes, and the more traditional reactors do. As I understand it, they are only used as a safeguard against coolant-leaks, or meltdown, or something.

If I recall, it was a containment dome that contained (imagine that) the 3-mile island accident.

[NNadir]

16. I've read a little bit more about this type of reactor, which has not been

necessarily my cup of tea, since I glaze over when someone says "once through fuel cycle."

Still, this reactor has many attractive features, not the least of which is that the reactor has very high burnups, about 200,000 MWD/ton (Megawatt days per ton) This compares with 30,000 MWD/ton with a typical Pressurized Water Reactor (PWR) and even better than a fast fission metal cooled reactor which yields about 100,000 MWD/ton. It is easy to convert these units of energy per ton into amount of fuel fissioned per fuel added to the system. At 200,000 MWD/ton, the percentage of fuel fissioned is about 20%. At 100,000 MWD/ton, about 10% of the fuel is fissioned. In ordinary US PWR's only three percent of the Uranium is fissioned. The pebble bed has much better resource use if you insist on a dubious once through fuel cycle.

The extraordinary burn ups in the pebble bed machine probably derive from the fact that the fuel is Thorium mixed with HEU. (Highly enriched Uranium). After a time Thorium transformed into Uranium 233 can act almost as a breeder, in which more fuel is created than is destroyed

A pebble bed reactor ran for about 20 years in Juelich Germany. It never had any problems per se but was shut down on the grounds in was a nuclear reactor and Chernobyl was a nuclear reactor. Relaying this story to a neighbor, I was able to convince him to stop driving his Ferrarri on the grounds that it was a car just like my Yugo blocking traffic on the San Diego Freeway.

It may seem absurd from a cost benefit analysis to put a containment building on this type of reactor, but I think all reactors, no matter what type, should have a containment building. This is because of the death exchange rate wherein more than 200,000 people die every year from industrial air pollution in the United States are less worthy of remark than the 200 or 300 people who have died because of Chernoybl. Thus every nuclear death is worth about 1000 non-nuclear deaths.

[Crachet2004]

6. If you REALLY want to get disillusioned, look up Hydrogen 3, on the moon.

They have evidently known about it since the 60's. We could have a functioning moonbase, harvesting facilities, AND a mondo observatory on Darkside for probably less than NASA has pissed away on ONE Rover mission...oh did you know, they say the latest mission reveals there may have been water on Mars, at one time. Idiots.

Then there is biodiesel...we could quickly ramp that up, along with ethanol-build the processing plants-everything, probably in just five years or so. Sooner, if they would crash the costs. There are almost no safety, or public health issues involved with any of this technology, so we could move quickly, and even use existing distributing networks. The diesel engine was originally designed to run on PEANUT oil, for crying out loud. And you can grow mustard seed almost anywhere. Short term, I favor this.

Then there is wind and solar. The efficiencies of these technologies are being held artificially low, compared to conventional means by simply NOT employing economies of scale in manufacturing the units. In other words, making solar panels in a ten worker shop costs a hell of a lot more per unit, than if we build a facility that covers two hundred acres and has a word wide sales distribution network. Have you seen the BP commercial claiming they are a leader in Solar? Well, it is no doubt true, but that is exactly what is wrong with Solar...it is enemy occupied technology territory. It would be economically feasible, only if some kind of Bill Gates gets involved.

Nuclear fission of any kind is simply NOT safe. The fuel is not safe, and is limited in availability on this planet. Because of safety issues, it takes a LONG time to bring a conventional Nuke on line...about ten years. Pebble Bed, because it is new technology, most likely would take at least as long, if not longer, at first. Anyhow, I just do not think building little Nukes all over the place is the answer.

Then there is Coal. Coal is what we are using for over half our electricity at present, and by me, what we will be using in to the future. Count on it. While everyone is talking about a new generation of Nukes, etc..., a new generation of Coal Burners are going to be built...they have already started, in WV, right above Morgantown (WVU, where the National Coal Labs are), in Monongahela County, on the Mon River. Probably building others, elsewhere.

What we use for fuel and power is not going to be submitted for public debate. There is always going to be a grid and centralized control of fuel and electricity...they would do it with the very air we breathe, if they could, because that is one way they maintain CONTROL over all us peons.

We have plenty of options...we are NOT going to run out of energy-the Universe is MADE of energy. The problems common people of the world face with regards to energy and its cost, are social and political, and can only be addressed through education.

Thank goodness for the Internet.

[phantom power]

7. coal

The cleanest-imaginable coal fired plant still releases gobs of CO2. Everybody treats CO2 as being a non-pollutant, but it's the most dangerous pollutant we produce considering it's impact on global warming.

Also, are you aware of what coal mining does to the surrounding environment? "Clean" isn't the word that comes to my mind :)

(edit) on second thought, maybe you were not advocating coal as a solution...

[Crachet2004]

10. I am not advocating coal, just making the observation that it is going...

To BE coal. And nobody is going to ask us what we think about that. The electricity generating industry plans decades ahead, and the plants we will be using tomorrow are being built today-or soon will be. I think the one in Monongahela County is probably a new generation plant, but I don't know that for sure.

There are several-to say the least-around where I live...in WV, on the Ohio River. They are putting various kinds of pollution gear on almost all of them, often at a cost of more than the plant cost in the beginning. I think the power companies are afraid the Democrats are going to get back in control, and fine the hell out of them.

As for the co2, one plant near me (8 miles)is doing an experiment at this time-they are drilling an experimental bore hole about 2 or 3 thousand feet deep. They plan to pump the co2 in to the ground, instead of the atmosphere-and no, I'm not kidding. They are doing it right now. They think the co2 will 'bind' (I think) with something else down there, and stay put. If the experiment is successful, they plan on boring a large diameter hole, thousands of feet deep, to handle the whole output of the plant...and it is one of the biggest there is-a 1300 megawatt unit. I just hope they know what they are doing. Their record is not the best with regards to experimental antipollution gear.

As for mountaintop removal...well, what can I say? Coal is like the oil industry in that they will simply buy politicians. They can buy media too, and shape public opinion any way they want.

The fact is, nobody CARES what we think. We have coal, and if the old plants are brought into compliance, the new ones are a go.

That is what I believe they are doing...from what I have seen.

[phantom power]

14. I wish I could believe you are wrong, but evidence suggests

otherwise.

All of these "carbon sequestering" ideas make me very skittish. I can't prove that they won't work, but they all seem like the sorts of adventures that will have unintended consequences, and not in a good way.

I mean, how do you credibly predict the geological effects of cramming giga-tons of CO2 into the ground? Chemical reactions, mechanical stresses, god knows what-all...

And then there's that idea for dissolving it all in the ocean. Basic chemistry guarantees that it all turns into carbonic acid, but who the hell knows what that does to a marine ecology. Nothing good, I bet.

[Massacure]

9. I disagree with you

1) Tritium requires fussion reactors. There is no working fussion reactor yet.
2) There is no way you could harvest Tritium for 800 million dollars. (the cost Spirit and Opportunity rovers just sent)
3) Whats the point of economy of scale if no one will buy them? If you lower the price from $3.50-4 per watt down to $2 per watt, how much will demand increase? Enough to justify producing so many solar panels?
4) Third generation nuclear reactors emits less radiation to the outside than smoking one cigarette. Unfortunately the U.S. still runs on second generation, but more people die from coal than from nuclear power.
5) Coal prices are fixed to that of oil, and as oil peaks, coal will get very expensive. Plus there is still that problem with Global Warming and air pollution. Sure the new ones are twice as efficiency, but they are still more polluting than nuclear.
6) When someon develops cheap solar, the grid will pretty well decentalize. I won't hold my breath though.

[Crachet2004]

11. The Itar reactor is going to be built, either in Japan or France...

I believe...look it up, it is interesting. The US wasn't even much involved...but we have known about the H3 on the moon for forty years-which is an almost Biblical length of time to do...nothing, with something that could be the answer we are looking for.

But for the present, I agree it is somewhat 'out there'. But if we had a moonbase, I think one thing might lead to another, and who knows? Just the observatory would justify the base, in my mind, but that is the subject of another thread, I suppose.

As for the discussion on economies of scale...whatever is cheapest and best is what I believe will be successful in the market. Build a big enough plant, and solar panels can be produced cheaply enough to compete-that is the key, and it hasn't been done yet. It is a myth that Solar is not efficient enough. Efficiency=cost of unit/watts produced. If cost per unit goes down, efficiency per watt per unit of cost goes up. See? They are an artificial things, these efficiency ratios. They can, and are, being manipulated. Almost everything IS.

One thing though...I don't see why you think the price of coal is tied to oil? We have hundreds of years of coal for the whole nation, in my state alone. Millions of acres of the best coal reserves have always been owned by the oil companies in WV, but only to hold it OFF the market, so oil can compete. That is why we have our very own Rockefeller, you know? To keep the world safe for oil. Nothing can compete with coal in an unrestricted environment...we have too much of it, and it is easy to strip mine out (mountaintop removal).

Understand, that I do not really want to burn coal. I just think we are GOING to, because it is what we have. And because it is what we are largely doing NOW. I wish we were going a different way, but I am not counting on it. The big money men have too much invested in existing systems, and they run this country.

[phantom power]

13. Spelling police: It's "ITER", not Itar.

The U.S. did withdraw from the ITER project, apparently to conduct our own independent fusion research.

More counter-productive unilateralism.

[Crachet2004]

17. Thankyou, and yes, I agree.

But it is evidently gonna be built with or without us...which is a good thing.

[Massacure]

15. A lot of coal comes from strip mines and you need to move a lot of dirt

Using huge vehicles that consume large amounts of diesel fuel -- made from oil.

Making enough biofuel for driving would be a big enough tasks, trying to make it for mining would be worse.

Also, about the solar panel thing. Lets saying you drop the cost in half by beefing up production by 10 times. What happens if demand only doubles or triples? What will happen to those other 7-8x the normal production?

[Crachet2004]

18. I am pretty sure there will always be fuel enough to dig the coal...

That powers over half our electricity generating capacity. Also, the Germans, as far back as WW2 had the coal gasification technology necessary to fuel much of the wehrmacht, after losing most of the oil fields they had captured earlier. Jimmy Carter, had he been re-elected, wanted to build an absolutely huge prototype plant of this description in the county I live in, here in WV. Of course, Reagan scrapped that, pronto. The Germans could even make a kind of margarine from coal...carbon based, you know?

But what I had in mind on Solar, is a little larger than what you seem to think I mean. Today, Solar panels sell for about $3.50 a watt. What if we set up a plant big enough to get operating costs for the plant down to about a dime? How would that be? Sell them for 15 cents a watt...cheap enough to sell like hotcakes. The only thing I can think of that would stop this from happening, would be scarcity of material (which would drive cost back up), but as far as I know (and I am no expert)the critical material is silicon, and some glass and wire. Again, I could be wrong, but if material needed for production is abundant, economies of scale are the only relevant rule...as Solar is certainly better, at least in areas where the sun shines a lot. And as I say, could be made cheaper, and therefore more efficient than, conventional systems.

Arizona and New Mexico could then be the new energy capitals of the US.

But they won't do it, there is an ongoing humongous investment in coal. Billions are being spent on pollution gear, right now, on existing power plants.

Like I said, while we are debating, the power companies are building, and they are not building nuclear...in fact, they are shutting those down, as their lifespan elapses. Some, like Maine Yankee, even before. Some, like Zimmer, were never even put on line. Nuclear is a pain in the ass, for power companies.

The big bucks are being spent now, and it is being spent on coal.