Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
REP. BARTLETT: I get widely divergent estimates of how much fissionable uranium is left in the world, from 30 years to 200 years. Before we can really have an effective dialogue about how to address this problem, we need to have an agreement on what the problem is. And there is just so much difference of opinion out there, and I talked to the National Academy of Sciences. They would be delighted. We need to find the money for them. We need an honest broker somewhere that tells us roughly what the truth is because we have widely divergent opinions now as to how much fissionable uranium is out there.
MR. DEFFEYES: I suggest you look at the Scientific American for January 1980, Deffeyes and MacGregor, on the world uranium supply.
REP. BARTLETT: And how much is there, sir?
MR. DEFFEYES: Every time you drop the ore grade by a factor of 10, you find about 300 times as much uranium, so that going down to the ore grade of - going down through the ore grades continues to increase the supply. But just about the time we were writing that Scientific American article, these enormously rich deposits, and big deposits in Australia and Canada sort of blew away our early estimates and we had to quickly increase the estimates. There are deposits in Saskatchewan so rich that the miners can’t be in the same room as the uranium, where the uranium is being mined. They mine it by remote control. So at the moment we’re swimming in uranium, but the Deffeyes-MacGregor piece, which comes out with a Hubbard-like curve, says that, no, we can go on down, and specifically we don’t need a breeder reactor.
Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
As we all know - energy is always conserved, it cannot be created or destroyed.Tanada wrote:By definition a breeder reactor is any reactor that contains more fissionable fuel mass in its core at the end of its fuel cycle than it contained at the beginning of the fuel cycle. In other words a breeder makes more fissionable fuel than it consumes through fission.
cube wrote:As we all know - energy is always conserved, it cannot be created or destroyed.Tanada wrote:By definition a breeder reactor is any reactor that contains more fissionable fuel mass in its core at the end of its fuel cycle than it contained at the beginning of the fuel cycle. In other words a breeder makes more fissionable fuel than it consumes through fission.
So how is it possible for a breeder reactor to "produce" more fuel then it consumes?
here's an example:
Imagine a lock box filled with coal. If you take a lump of coal and use it to burn a hole into the lock box, giving you access to the larger quantity of coal inside, you've just "created" more fuel then what you've started off with. Perhaps a more accurate statement would be, you now have greater access to more fuel/energy then what you started off with. The laws of physics have NOT been violated.
A breeder reactor works the same way.
U-238 can be thought of as the "lock box filled with coal" and U-235 can be thought of as the lump of coal used to gain access to the "lock box". U-235 may be in short supply but this planet has a generous supply of U-238, so a future shortage of nuclear fuel would be highly unlikely.
This may seem like a half-baked analogy but at least it helps to dispell the myth that somehow breeder reactors violate the 1st law of thermodynamics which it certainly does NOT. I lost count how many people who have proclaimed that breeder reactors don't work.
Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
Heavy water is manufactured by electrically separating the Hydrogen and Oxygen in the water, then putting the Hydrogen through an enrichment process to concentrate the Deuterium which is about 1 part in 6000 of average surface water on Earth.
J_S_Bokchoy wrote:I'm trying to figure out how expensive natural uranium will get before enrichment facilities find it economical to go back and extract more u235 from their depleted uranium. For back-of-envelope calculation purposes, I assume 400 nuclear power plants each using 30 tons fuel annually for 25 years, with each ton of fuel burned leaving 7 tons of depleted uranium behind at the enrichment plant, with 2/10ths of a percent U235 still left in it. That would be 400 x 30 x 25 x 7 x .002, or 4200 tons U235 that once separated could be blended at a 24 to 1 ratio with U238 to make 105,000 tons of burnable fuel, or 105000/(400x30)=8.75 years supply, long enough to bring plenty of new production into the market. What I can't even guess at, is how much more marginally expensive it becomes to centrifuge out that last ounce of U235, when the decisions have already been made once that it's not worth it. Any ideas? When I tried to guess the price where power companies would find it cheaper to switch to natural gas, it came out around $500 a pound, so maybe it's a moot point if recovery from depleted U works out even higher.
(From CLICK )The specific energy consumption is 2300-3000 kWh/SWU for Gaseous Diffusion, versus 100-300 kWh/SWU for gas centrifuge. The number of stages required to produce LEU is about 30 times larger in the diffusion plant than in the centrifuge plant. The corresponding equilibrium time is significantly longer in diffusion plants (months) as compared to centrifuge plants (hours). This effect, more intensive when the diffusion plant processes Uranium with higher enrichments, makes difficult and time consuming any significant change of the modus operandi of a gaseous diffusion plant. The large in-process inventory in the diffusion plant (a few tons in a small-scale diffusion plant) indicates the importance of closing the Uranium balance in this facility. On the other hand, for centrifuge plants, the small equilibrium time, small in-process inventory and the flexibility to change the cascade design (parallel to series) determine the importance of verifying that the plant is operating as declared.
Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
J_S_Bokchoy wrote:AND please disregard preceeding inquiry, I forgot to include power expense on the right hand side. After that my hypothetical breakeven point was only $20 so the question must be pointless if the price is double that already. Maybe hedge fund speculation, panic inventory building or even the limited enrichment capacity now in operation washes out mere cost accounting.
Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
I think (anybody who disagrees feel free to step in) MOST breeder reactors were not built with the primary intention of supplying energy.sch_peakoiler wrote:a layman's question on fast breeders.
Everywhere where I read about those breeders there are arguments being made that the reactors are unprofitable, unreliable and things.
cube wrote:I think (anybody who disagrees feel free to step in) MOST breeder reactors were not built with the primary intention of supplying energy.sch_peakoiler wrote:a layman's question on fast breeders.
Everywhere where I read about those breeders there are arguments being made that the reactors are unprofitable, unreliable and things.
Since breeders can "produce" Plutonium it has definite military applications. Modern nuclear bombs are fusion and not fission bombs. Therefore they do not recieve their power from plutonium per say. Instead the PU is used to create a fission reaction which produces massive amounts of heat. The heat "triggers" the fusion reaction. Basically every fusion bomb is actually 2 bombs in one. A fission reaction is necessary to create a fusion reaction.
Because of its significant military applications I would assume all breeder reactors must be government owned. That would explain their unprofitable history.
Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
Users browsing this forum: No registered users and 18 guests