# Google Solve for X Retreat

Each of us had to come up with an >X< — a big hairy topic that needs addressing,

Today, we are brainstorming "radical technology ideas for solving global problems. Radical in the sense that the solutions could help billions of people. Radical in the sense that the audaciousness of the proposals makes them sound like science fiction."

More to come on Tuesday. For now, they have a teaser video [update: site just went live with video]

jeany777, RRNeal, vennettaj, and 2 other people added this photo to their favorites.

1. surprisingly, nothing at all. In the 1950's when the possibility of using fission as a source of electricity was first being considered, most of the existing knowledge was an outgrowth of weapons programs. The government funded several alternatives including a working thorium based reactor at Oak Ridge laboratories but when the chief advocate for thorium based reactors passed away, simple politics determined the projects which received funding. Despite all of it's benefits thorium fell by the wayside.

For anyone interested in clean energy or energy independence from fossil fuels the first 5 minutes of this video contrasts todays technology with thorium technology. The rest of the video is an in-depth examination of both technologies and how we got to where we are today. This video as well as others are also available at www.energyfromthorium.com

My interest in this technology is entirely environmental. Apart from living on this planet I hold no personal stake in this technology of any kind.

2. > To burn a ton of coal requires 246 tons of water?
> That does not pass the sniff test.

The value actually seems reasonable.

A typical coal plant has a theromdynamic efficiency of about 30%.
So, a 1GW (electric) power plant needs a power input of about 1GW/.3 ~= 3.3GW (thermal)

Energy density of 1kg of coal: about 6.67 KWh
The energy content of a ton of coal is thus about 6.67 MWh, of which 30% — i.e. about 2 MWh — leaves the plant as electrical power, and the rest — i.e. about 4.47 MWh — must be evacuated by the cooling circuit.

4.47 MWh ~= 16.1 Gigajoules ~= 3.844 Gigacalories

246 tons of water = 2.46 10^8 grams of water.

Energy required to raise the temperature of 1 gram of water by 1 degree Celsius: 1 calorie.

With 3.844 Gcal, one can thus theoretically raise the temperature of 246 tons of water by 15.63 degrees Celsius.

In practice, if cooling towers with sprinklers are used, the enthalpy of evaporation ensures that a significant part of the heat load will be carried away by water vapor. Thus, the liquid water's temperature will change by much less than 15.63 degrees. This is a good thing, as environmental regulations typically limit the temperature difference between the cooling water inlet and outlet of a power plant using a natural body of water (river etc.) to a few degrees Celsius.

Hence the need to use a lot of water so as to minimize the heat load and impact on the surrounding river's biotope, and the reason why power plants are generally sited near an abundant source of cooling water.

> What held back thorium from being used in new reactors?

A nuclear power plant, like a coal power plant, works by generating heat. That heat is typically used to boil water, and the resulting high-pressure steam is used to drive the turbines to which the generators are attached.

A conventional nuclear reactor uses solid pellets of uranium (and some plutonium), assembled in fuel rods.
OTOH, a thorium reactor would have a "core" that is liquid — molten lithium fluoride and beryllium salts carrying thorium and uranium.

A decent-sized — e.g. 1GWe — thorium reactor would need to circulate several tons of molten salt per second to the heat exchanger, where the steam driving the turbines would be generated.

Circulating several tons per second of potentially reactive metal salts, heated to about 400 degrees, is a serious engineering challenge.

Fast breeder reactors, which typically used molten sodium as the reactor core's coolant, present similar difficulties. Water slows down the neutrons too much, which hinders the operation of a breeding reactor, hence the selection of sodium — with its low neutron absorption cross-section — as the primary circuit's coolant.

The engineering reality is that it's horrendously difficult to create a cooling circuit (including pumps and pipings) able to withstand for years the circulation of several tons per second of molten sodium metal.

I'm afraid there hasn't been a single FBR in the world that didn't experience leaks in its sodium circuit.

Once leaks happen, sodium is much more complicated to deal with than the water used in normal nuclear reactors, for it reacts explosively with water. And unfortunately, some water is generally present near the sodium in a FBR used to generate power: how else would the steam used to drive the turbines be generated ?

These difficulties explain why the number of actually operational FBRs in the world, even after decades of development work, is exactly zero.

High-temperature lithium molten salt circuits carrying thorium and uranium, compared with molten sodium, would be even more "challenging", especially if a leak happens, as that molten salt would be transporting very radioactive materials, including the nasty actinides generated by the fuel's fission reactions.

3. All true and correct (I had done the same calculation), but it is disingenuous of organizations like Sourcewatch to imply that 246 tons is used to burn a ton of coal. The vast majority (except for the tiny fraction that evaporates in the cooling tower, if one is used) is returned to the source, or re-used entirely within the plant. It's not "used" and removed from inventory in the sense that the coal is. They do a disservice implying that it is.

4. It would be nice if we all stuck to the facts.

The BN-600 is a fast reactor that has been in operation for more than 30 years. It is so trouble free that experts like "nhr" above didn't even knew it existed, despite being mentioned on the wikipedia page that nhr used to "prove" his erroneous assertion that there are zero FBRs in operation.

Furthermore, the EBR-II ran for 30 years without any significant mishaps even after running chernobyl and TMI simulations. When they disassembled it, they found that the materials were as "clean" as they were on day 1 with no corrosion.

The problem with FBRs is really the misinformation being spread about them, not the technology itself.

5. ...and the BN-600 is STILL in operation AFAIK.

They extended the license for another 10 years recently, so it will have been operating so trouble free for nearly 40 years that nobody knew about it.

6. And the only reason we shut down the FBR in the US is for poltical reasons, not for technical reasons. See Steve Kirsch's letter to Heather Zichal regarding the Integral Fast Reactor (IFR) for an extensive writeup as to why it was cancelled and why we aren't restarting it.

The reason we aren't restarting it is nobody is putting it on the priority list because nobody knows the real facts about it and when you send the White House stuff like my memo that explains the facts, nobody reads it because they think if it were true than more people beyond Bill Gates, myself, our nation's most qualified fast nuclear scientists, GE, the President of the American Nuclear Society, Congressman John Garamendi, James Hansen, Mark Lynas, Stewart Brand, Barry Brook, Tom Blees, etc. would be supporting it.

So it's a chicken-egg problem. If you ask Al Gore why he isn't supporting it, he'll say "I'm technology neutral." If you ask the Sierra Club, they'll say, "we are not opposed to it."

7. > The BN-600 is a fast reactor that has been in operation for more than 30 years
> It is so trouble free that experts like "nhr" above didn't even knew it exist

The BN-600 had, indeed, escaped my attention.
Still, one operational reactor, compared with the total deployed number of more conventional nuclear reactors, be it in Russia or elsewhere, is hardly indicative that circulating liquid sodium or radioactive molten salts is seen as cost-effective or safe or advantageous by most decision-makers in the nuclear power industry, be it in Russia, the US or elsewhere.

Note that I'm just a disinterested observer, and I don't have a dog in this fight.
If the challenges I outlined in my previous comment can be shown to have found effective solutions, then I'm sure the support base for these fuel-efficient reactor technologies would grow quickly.

The number of cycles the water goes through the cooling circuit is variable, but not a factor in the flow calculation: regardless of the number of cycles, at some point in time, the water will be too hot to be useful for cooling the reactor.
At that point, the hot water must be replaced with cold water.

The power plant, considered as a thermodynamic entity, cannot maintain its temperature — i.e. prevent its entropy from rising — if it can't discharge heat to the external environment at the rate its reactor produces it.

The only way to discharge the heat is by pumping in cold water so that the rate of heat production and the rate of negative calories — a.k.a. frigories — provided by the cold water are in equilibrium, and this is the principle underlying my calculation.

To make an astronautical analogy, heat can be considered a pollutant making water unfit for use in a cooling system, just like the carbon dioxide exhaled by human respiration is a pollutant as CO2 can, at high enough concentrations, become toxic and make the air unfit for respiration.

Hence the need for CO2-scrubbing equipment in environments where air must be reused, like in the Apollo spaceships.

For a power plant, the "scrubbing system" acting as a heatsink and providing the power plant with "scrubbed" water from which the "heat" pollutant has been removed is the Earth's geophysical processes.

8. nhr: The soviets consider the BN-600 one of their best performing reactors.

The reason there is only one fast reactor is because it is HARD TO GET RIGHT.

It took our smartest people DECADES to figure it out. Nobody in the world has better technology than we do. So after developing this amazing technology and solving all the hard problems to get it to work totally reliably for 30 years, the government said, after 30 years of bi-partisan support of the effort, that we NO LONGER NEED CLEAN ADVANCED NUCLEAR POWER. That is the justification Clinton used to cancel it, not because it wasn't cost effective or didn't work.

General Electric believes IFRs are very cost effective. So do the scientists who designed it.

Of course, some people don't believe that. These are all people who do NOT have first hand experience with fast reactors. I don't know of anyone who worked on the IFR who says it is not cost effective. Do you?

The only way to resolve it is to build them and ride down the cost curve.

Bill Gates wouldn't be investing the money he's investing in his fast reactor (an IFR derivative) if he didn't believe these reactors are cost effective. He's very very smart.

Had we not cancelled the IFR program (which was cancelled for political reasons), we would be far down the learning curve.

Our technology is much more cost effective than the Soviet reactor because we use metal fuel.

And we should never assume the stuff we invented 50 years ago can't be cost reduced even more. That's like saying computers built 50 years ago can't be made cheaper and most cost effectively. Once these reactors are a national priority, it is amazing what people will think of.

To summarize:

1. The best way forward as far as Gen.4 nuclear reactors are concerned, according e.g. to the scientists who worked on the development of the IFR is, well, the IFR.
Let me point out that the IFR team specifically selected a sodium "pool" design, instead of the sodium "loop" design.
In a "pool" design, the reactor core is immersed in a pool of molten sodium, which is, in turn, cooled by a secondary sodium circuit (or "loop") connected to the heat exchanger / steam generator.
The envisioned fuel, once enriched by the IFR, is reprocessed on-site e.g. by electrorefining and then re-used – hence the name, "Integrated" Fast Reactor.

2. Bill Gates invested in TerraPower, which specifically choose to go with a sodium "loop" design, instead of the pool design. TerraPower's envisioned fuel is also "once-through", without reprocessing.

3. Thorium reactor proponents argue that instead of the conventional, solid U or Pu nuclear fuels, a circuit of high-temperature molten salts carrying radioactive isotopes should be preferred. The fuel in the circuit presumably needs periodic reprocessing to remove the "nuclear poisons" — i.e. the fission by-products that would absorb the neutrons and impede the Th to U fertilization process.

So, even if we ignore the implicit choices made by most decision makers in the overwhelming majority of the production nuclear reactors across the globe, we have the aforementioned three groups of presumably smart people who already have divergent opinions as to what the preferred design of a safe and cost-effective nuclear reactor should be.

About the only commonality these designs have is that they don't use an established technology — water coooling circuit, — but instead rely on ideas that have, er, a "proven" worldwide track record of reliability and accumulated engineering experience like circuits of liquid sodium or radioactive molten salts.

We also have various unspoken assumptions, e.g.:

• Leaks in the sodium or radioactive molten salt circuit would never happen; that's a mere engineering and manufacturing and plant monitoring and operational and maintenance problem that's been solved.

• Loss of electrical power leading to the shutting down of coolant pumps is something that would never happen.

• In the IFR, natural convection in the pool is supposed to be sufficient to cool the reactor core; sodium is kept at a low pressure so as to minimize the risk of leaks and keep vessel and piping costs low, but said sodium would never boil (trust us). The fact that the IFR has a positive void coefficient, leading to increased heat output from the nuclear fuel if bubbles were to form in the sodium can be, well, ignored.

• The IFR's secondary sodium cooling circuit is presumably an add-on, as the IFR sodium pool is presumably capable of eliminating heat autonomously so that internal convection takes place, perhaps by externally radiating tens of megawatts of heat away if the secondary circuit is shut down e.g. due to a leak or a loss of electrical power. It must be quite toasty near the IFR's primary sodium pool.

• Even if leaks e.g. to a Th+U+actinides molten salt circuit were to happen, decontamination of the radiation caused by nuclear fuel is something that's proven to be, er, quick and inexpensive.

• Even if radioactive contamination due to leaks were to happen, it should, er, never lead to an event such that it would make more economic sense to shut down, write off and decomission the plant.

Note also that:

• General Electric etc. develop and market reactors which they'd obviously describe as "cost-effective". GE etc. also stand to benefit from the awarding of nuclear reactor procurement contracts; they "privatize" the profits they earn on such engineering and construction projects. Any financial losses, be they caused by the unexpectedly low operational efficiency of the delivered "fuel-efficient & cost-effective" power plant due e.g. to technical "glitches" while the manufacturer "accumulates experience and rides down the cost curve", or the possible writing off of the not unsubstantial sunken costs of a contaminated power plant can be "socialized" and aren't GE's problem.

• For TerraPower, it's interesting that enlightened countries like China, whose government has an excellent record for transparency and social accountability, happen to be more interested in their reactors than e.g. the more socially backwards countries of the West.

10. wha.. cool chat..
(of which i understood not much, but the argument that bill gates is very smart and that's why the reactor must be good cracked me up..just as a choice of argument..not saying he's not smart :p)

11. "Richard DeVaul The #solveforx conference videos and other materials should be posted by the end of the day today. wesolveforx.com ".

Can' t wait to see them =)
Thanks for sharing Steve

12. some anticipatory buzz at Mashable

I also added some photos above. Here are the Happy Google organizers at the close:

Astro Teller, in the middle, did the opening for my tech talk.

13. love to see that you are using Flickr as a forum

14. thanks. The site just went live with videos of some of the talks. www.wesolveforx.com

I suggest starting with Mary Lou Jepsen's talk on reading the mind (HD version).

And I added a new post with most of my notes here

15. The most efficent method of addressing carbon foot prints is reducing the size of our global population. So an advocate can contribute by not having kids.

16. Started with Mary Lou Jepsen's talk and the brain astonishing results based on imagination

17. When are they going to post your talk?

18. I don't think they will, as I was part of a couple of the responses to the talks, and I think that was off the record.

But you can see me discuss my X ad nauseum in my Google Tech Talk