# Fusion in trouble (again)

1. Jun 17, 2009

### aquitaine

More failure and disappointment for something that was so promising

Notice the last statement. So it doesn't have enough money because commodity prices have gone up so much, wouldn't scaling it back starve the project even more? We need real commitment people, it's starting to look more and more like our space program.

2. Jun 17, 2009

I've always figured that fusion power wouldn't be a reality until late this century, just because of all the new science required. But I was surprised that the budget for ITER is only $16 billion! That seems pretty cheap compared to Manhattan or Apollo, and the potential gains are even greater. With all the money the US gov has been flushing down the tubes lately it's a wonder why we haven't started our own full-scale tokamak project. 3. Jun 17, 2009 ### mathman The laser fusion program (NIF) is a U.S. gov't paid for program. 4. Jun 17, 2009 ### aquitaine That's an amazing, baffling mystery, why don't we spend more? In inflation adjusted 2008 dollars, the manhattan project costed$24 billion and employed 130,000 people. The Apollo project cost \$135 billion in 2005 dollars and employed 400,000(!) people. So given the enormous potential for fusion power, why aren't we doing something like this for it? I suppose it is just because we don't care.

5. Jun 18, 2009

### ppnl

6. Jun 19, 2009

### joelupchurch

The Manhattan project had a working bomb in 4 years and the Apollo program has a man on the moon in 7. The NPV of a fusion power plant in the 22nd century is what?

The trouble isn't with fusion; it is with how we generate electricity. As long as we are limited to gas and steam turbines, fusion has no advantages over fission. We can't even build turbines to handle the temperatures fission can produce. We have enough reserves of thorium and uranium to last us for thousands of years.

We will probably have working fusion powered interplanetary spacecraft, before we have a fusion electric station on earth, but nobody is going to fund that until we have a cheap way to earth orbit.

7. Jun 19, 2009

### aquitaine

That's not entirely true, it doesn't need as much fuel (not like fission needs that much to begin with) but it also doesn't generate transuranic waste. But overall I agree with your point.

Run with it, if they get it to work the awesome. As I understand it the tokamak's are farther along. The problem in the case of ITER is generally political.

8. Jun 19, 2009

### Astronuc

Staff Emeritus
What does fission or fusion temperature have to do with turbines?!

Fission and fusion produce thermal energy - kinetic energy of products - which is transferred to a working fluid, e.g., water, which produces steam, which is forced through a steam turbine, which drives a generator, which produces electricity. There is a train of high and low pressure turbines and maximum temperature is about 270°C (~823 psig). Traditional nuclear plants (LWRs) use the Rankine cycle for thermal to mechanical energy conversion.

Ref: http://www.nrc.gov/reactors/new-reactors/design-cert/ap1000/dcd/Tier 2/Chapter 10/10-1_r3.pdf

High temperature gas-cooled nuclear plants are envisioned to use the Brayton cycle, Rankine cycle, or a combined Brayton/Rankine cycle.

Fusion offers the potential for direct coversion via the magnetic separation of He-ions and electrons. That has yet to be perfected at the commercial level, just as we are waiting impatiently for a commercial fusion plant.
And the basis of this is what?

Last edited by a moderator: Apr 24, 2017
9. Jun 19, 2009

### joelupchurch

Has anybody got direct conversion to work even in the lab? I've only seen paper studies. I think having a power plant with no moving parts would be cool.

As for the spacecraft comment. Are you contending that a fusion spacecraft isn't simpler that a fusion power plant? I would think that not having to maintain containment or even reach breakeven for a useful spaceship would make it a lot easier. Not to mention, not having to worry about the EPA or the NRC when you are on the way to Saturn. :-)

Here is an article on various fusion spacecraft concepts:

http://www.thespacesite.com/space_nuclear_fusion_propulsion.html"

Last edited by a moderator: Apr 24, 2017
10. Jun 20, 2009

### Astronuc

Staff Emeritus
I believe some concepts have been tested in the lab, e.g.,

What makes on think that a spacecraft fusion systems doesn't have to achieve or exceed breakeven? One has to heat the fuel, have it acheive fusion and expel the products as propellant. One must produced sufficient energy to achieve fusion conditions (not 100% efficient), raise the stored propellant to fusion conditions, and make up for the energy expelled with the propellant. If the reactor does not exceed breakeven, then one is not going anywhere.

One still needs the same fusion system, whether producing electrical energy or propulsion. The containment (or does one mean confinement?) is trivial compared to the fusion reactor. Confinement is not trivial. A spacecraft system is not simpler than a power plant, and in some ways, it's more complicated.

Not much technical detail (actually there is no engineering analysis to support any of the concepts) and a lot of 'pie in the sky'. High specific impulse does not guarantee high thrust, and in fact high Isp fusion systems usually produce low thrust due to the very low density of fusion plasmas. Low thrust in conjunction with massive systems (power plant and fuel) produce low acceleration.

Fusion for space propulsion is off-topic. The OP concerns ITER and the increasing cost of the project. Yes increasing costs of energy and commodities have produced higher costs for projects such as ITER and the next generation of nuclear plants.

Last edited by a moderator: Apr 24, 2017
11. Jun 20, 2009

### joelupchurch

I agree, spaceflight is off-topic.

The basic point I was trying to make is that the world has many pressing problems and unless there is a plausible path to a fusion electric plant that is cheaper to build than a fission plant of similar capacity in the next 50 or 60 years, then it is going to hard to get public support.

We might get to fusion in 50 or 60 years, but cheap fusion is probably much further off.

12. Jun 21, 2009

### joelupchurch

I started a separate thread on Fusion Space Propulsion.

13. Jun 27, 2009

### Xnn

Sorry, but truthfully, there doesn't appear to be much reason to conclude that fusion can ever be used to economically generate electricity.

That doesn't mean the Gov't wont spend research dollars on Fusion. After all, Gov't spending is one way to stimulate the economy. But, don't confuse that spending with praticality.