Removing Hot Air from Nuclear Power Plants; Scientists Convert Nuclear Energy to Power without Steam

Apr 13, 2009

(PhysOrg.com) -- For years, researchers have been in search of an economically feasible method of converting nuclear energy directly into electricity. Now, University of Missouri researchers are developing an energy conversion system that uses relatively safe isotopes to generate high-grade energy. A system that directly converts nuclear energy into electricity would be cheaper than current nuclear conversion technology.

"Direct conversion of nuclear energy has not been possible previously," said Mark Prelas, professor of nuclear engineering and director of research at MU's Nuclear Science and Engineering Institute. "Current nuclear technology has an intermediate thermalization phase between the nuclear reaction and when the energy is converted to electricity. This phase reduces the efficiency of the energy conversion process."

MU researchers have developed a process called Radioisotope Energy Conversion System (RECS). In the first step of the process, the ion energy from radioisotopes is transported to an intermediate photon generator called a fluorescer and produces photons, which are the basic units of light. In the second step of the process, the photons are transported out of the fluorescer to photovoltaic cells, which efficiently convert the photon energy into electricity.

Since the 1980s, MU researchers have worked to develop electrical power from a nuclear light bulb, which is a way of generating hydrogen, electrical power and laser energy directly from nuclear reactions. The nuclear light bulb was based on the Photon-Intermediate Direct Energy Conversion (PIDEC). PIDEC converts the high-grade ion energy to photon energy. In addition to improved efficiency, the PIDEC process also promises advantages in volume, mass and cost.

"RECS effectively utilizes the PIDEC system," Prelas said. "The system we are developing is mechanically simple, potentially leading to more compact, more reliable and less expensive systems."

Currently, the only method to convert nuclear technology into electricity is through nuclear fission. In the process, water is heated to create steam. The steam is then converted into mechanical that generates electricity.

Prelas has worked with industries, such as British Nuclear Fuel, Daimler Bentz and the U.S. Semiconductor Corp. on RECS commercialization issues. He is the recipient of the 2009 Glenn Murphy Award given by the American Society for Engineering Education.

Provided by University of Missouri

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User comments : 25

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grahf
3.2 / 5 (6) Apr 13, 2009
I'm not sure why they have to convert to photons first, that is going to produce a significant loss. What they need to do is develop a new material that will do the conversion directly.
dan42day
3.5 / 5 (4) Apr 13, 2009
"Currently, the only method to convert nuclear technology into electricity is through nuclear fission."

Ever hear of a radioisotope thermoelectric generator (RTG)?
GrayMouser
2.3 / 5 (4) Apr 13, 2009
"Currently, the only method to convert nuclear technology into electricity is through nuclear fission."

Ever hear of a radioisotope thermoelectric generator (RTG)?

That is still driven by fission. The neutrons are used to generate heat.

A "nuclear light bulb"? Neat! No more incandescent or florescent bulbs...
unxconformed
3.3 / 5 (4) Apr 13, 2009
"Currently, the only method to convert nuclear technology into electricity is through nuclear fission."



Ever hear of a radioisotope thermoelectric generator (RTG)?


That is still driven by fission. The neutrons are used to generate heat.



A "nuclear light bulb"? Neat! No more incandescent or florescent bulbs...


Actually, RTG's don't use fission. They use the decay of the material in them (like Pu238) to generate heat which is converted by a TEC (thermal electric conductor) to directly convert heat to electricity. The efficiency is actually quite low so it really is only useful for small low power applications.

This company and tech here http://www.betavoltaic.com/ has something that converts the beta emissions of an isotope decay into electricity directly. So this article is maybe a little out of date on what is actually available as far as nuclear power is concerned...
phlipper
4.2 / 5 (5) Apr 13, 2009
It's a waste of time to develop any kind of nuclear energy in the US. Here, we've made up our minds that we would rather use wind mills, rubber bands, and bicycles.
nkalanaga
3 / 5 (3) Apr 13, 2009
The RTG's still use some fission, as that one way plutonium decays. They do NOT use a fission chain reaction, as in a power reactor, but rather allow the Pu to decay more or less naturally. Thus, an RTG cannot explode, but still produces some fission byproducts.
E_L_Earnhardt
1 / 5 (11) Apr 13, 2009
You are ON THE RIGHT TRACK! THE ATOMIC BOMB RELEASES SO MUCH ENERGY IT FRIES EKECTRONIC EQUIPMENT WITH HIGH-SPEED ELECTRONS! TRAP THEM AND YOU HAVE A "POWER PLANT"! FRACTURE AN ATOM AND YOU SET THEM FREE!
unxconformed
3.8 / 5 (4) Apr 14, 2009
The RTG's still use some fission, as that one way plutonium decays. They do NOT use a fission chain reaction, as in a power reactor, but rather allow the Pu to decay more or less naturally. Thus, an RTG cannot explode, but still produces some fission byproducts.


You are partially correct, you can have spontaneous fission with decay but the RTG's were not designed to "use" fission. The byproducts you speak of are extremely small and not very dangerous since the quantity is extremely low, almost negligible when compared to fission...
JustAnyone
5 / 5 (2) Apr 14, 2009
As I have mentioned elsewhere, it's theoretically possible to stimulate negative beta decay of a light isotope like lithium 7 into beryllium by adding a photon of exactly the right energy to stimulate the quantum state to change. This releases an electron (and an anti-neutino, big whup) which can be slowed and captured through wire coils, directly generating electricity from nuclear decay. No radioactive by-products are produced: In fact, the overall radioactivity is the thing changed to power. Research requirements seem to be access to a free-electron (tunable) laser, and an apparatus to heat and (completely) ionize lithium.

Blog post on this at justanyone.com
Birger
4.3 / 5 (4) Apr 14, 2009
I am a bit disappointed that the article does not mention the practical expected efficiency of the new conversion process. The current process -steam turbines driving generators- has an efficiency of ca. 40%. Without knowing how great the likely improvement will be, companies will be unwilling to invest in research and development for equipment able to endure the harsh conditions inside a reactor -a "non-trivial" engineering problem.
vivcollins
4 / 5 (2) Apr 14, 2009
Was it the SF author Robert Heinlein who wrote of a nuclear reactor surrounded by photocells to generate electricity in his early beltway based books?
docatomic
3 / 5 (2) Apr 14, 2009
I'm not sure why they have to convert to photons first, that is going to produce a significant loss. What they need to do is develop a new material that will do the conversion directly.




What "conversion"? Any beta-emitting radioisotope is already emitting electricity directly! Give me a chunk of 90Sr, and I'll make a more direct use of it. I'll stick it in a magnetron as a cathode, apply a strong magnetic field, and rectify the resulting RF output to DC for use directly. This nonsense about first converting the energy to either heat or photons is just wasteful and stupid! Can't anyone at all see the obvious? I don't believe it.
TJ_alberta
3 / 5 (1) Apr 14, 2009
docatomic: I somehow think that your hot cathode is only going to save the filament power. Could be wrong, but I have a feeling the RF energy is still going to be proportional to the current in the HV supply. However I believe your plan would result in a significant increase in microwave oven efficiency - and then you could really nuke your food.
docatomic
5 / 5 (1) Apr 14, 2009
Somehow, I get the impression that you don't understand what I'm talking about. The 90Sr cathode _is_ the HV power supply!

Cyril Kornbluth was right on the money, apparently.
TJ_alberta
3 / 5 (1) Apr 14, 2009
OK how many watts per gram of 90Sr cathode do you expect? (average for the first 29 years)
docatomic
not rated yet Apr 14, 2009
OK how many watts per gram of 90Sr cathode do you expect? (average for the first 29 years)


I've seen a figure of 0.93W/g; however, that figure seemed to be indicating a thermal equivalent rather than direct electrical.

For direct electrical, I believe it would simply be the number of disintegrations per second (corresponding to the current value, accordingly) multiplied by the electron velocity (voltage).
daqman
3 / 5 (1) Apr 14, 2009
docatomic:. The isotope 90Sr emits beta radiation with an average beta energy of 0.196 MeV and has a half life of 28 years.

So one mole (6E23) of 90Sr (a honking big source!) with a half life of 28 years (8.8E8 seconds) generates an average of 6E14 beta decays/S, multiplied by the charge on the electron gives about 96 micro amps, multiplied by 0.196 MeV that is 18 watts.

So, you can quickly show that even a big lump of 90Sr would generate only a small amount of power.
daqman
4 / 5 (1) Apr 14, 2009
Just to add that the calculation I did was very "back of the envelope" to give a "ball park" figure. If you take into account that a mole of 90Sr weighs 90g you come up with a guestimate that isn't too far from the 0.93W/g in docatomic's post.

I think my main point is that we're not talking megawatts with this sort of nuclear battery.
docatomic
not rated yet Apr 14, 2009
Certainly not. However; at roughly a horsepower per kilogram, it is certainly not insignificant either - especially when you further take into consideration that such a device would deliver useful power _continuously_ for at least two decades, and do so with significantly greater overall efficiency than any equivalent RTG or supposed 'radiophotonic' conversion device.
JLMEALER
1 / 5 (5) Apr 14, 2009
Being a conservative, one would think I'd be agreeing with Nuclear power. It is destructivein the sense that we are placing hugely dangerous radioactive waste (35B tons per year per plant) into "safe" storage areas.
STUPID to say the least!

MEALER auutomobileplug is neededhere...

The MEALER of Mealer American Motors Corp is a non fossil fuel powered, non EV that wil also power your home when the interchangeable bodied car/truck is parked.

What will they do when this hits the market and I sell mfg rights to competitors and then the nuke plants become obsolete?

http://betterconstructed.com

JL Mealer
docatomic
not rated yet Apr 14, 2009
Well, if you want poorer performance... 63Ni spews out 66KV electrons to the tune of about six measly Watts per kilogram. But; be that as it may, several tonnes of it in the basement _could_ keep your house or your station at a nice perfect temperature - for a *century*. Keep the air purifiers and ventilation happy, too - and maybe even help move a bit of water..?

Think about _THAT_ the next time you wanna set anything down on another moon or planet, eh?
docatomic
not rated yet Apr 14, 2009
As I have mentioned elsewhere, it's theoretically possible to stimulate negative beta decay of a light isotope like lithium 7 into beryllium by adding a photon of exactly the right energy to stimulate the quantum state to change.


Yes; I have heard of this being done electrically, several decades ago... and I see your point; a laser *could* serve as well...

This releases an electron (and an anti-neutino, big whup) which can be slowed and captured through wire coils, directly generating electricity from nuclear decay.


Standard electromagnetic barrier with feedback, to work against - superconductive Lenz loop pairs, perhaps?

Research requirements seem to be access to a free-electron (tunable) laser,


I believe I've read articles before, of 'home-brew' type 'do-it-yourself' FEL projects, but I can't recall where.

..and an apparatus to heat and (completely) ionize lithium.


That sounds like an argon induction plasma torch, as typically employed for sample ionisation on ICP mass-spectrometer equipment. The one I worked on operated at a (feedback-controlled) power level of up to 2400 Watts, at a frequency of 27 MHz. It consisted of a tank coil of about five or six turns, constructed of 1/4" copper tubing in a spiral of about 1 3/4" and connected by means of through-mount bronze compression tubing fittings mounted through a rectangular ceramic plate and terminated in hose barbs, to which were clamped the Teflon tubing that served to conduct the current of highly-purified and de-ionised coolant water. Directly attached to the compression fitting's mounting flange bases were also wide flat lengths of copper strip, that served to connect the water-cooled coil directly to a tunable vacuum-capacitor that formed the counterpart component of the resultant parallel tank circuit, a basic RF resonator to dump a CB rig's max-level output juice into in order to keep the argon plasma all nicely actinic and everything.

Overall, good thinking! Might give my idea a run for the money, I figure. ;-)
Soylent
not rated yet Apr 19, 2009
So one mole (6E23) of 90Sr (a honking big source!) with a half life of 28 years (8.8E8 seconds) generates an average of 6E14 beta decays/S, multiplied by the charge on the electron gives about 96 micro amps, multiplied by 0.196 MeV that is 18 watts.

So, you can quickly show that even a big lump of 90Sr would generate only a small amount of power.


Compare it with a battery. Before lithium ion batteries you had to have surgery every few years to replace the battery if you had a pace maker; if you were one of the lucky few to get a plutonium-238 RTG based pace maker it would outlast its owner(there are people who still have them now after 20-30 years). It was considered acceptable to only have surgery every 10 years with lithium ion and with the paranoia of radiation plutonium pacemakers where phased out.

If you want to explore the outer solar system you pretty much have no other choice than using nuclear decay unless you can afford the added weight of a mini-reactor. Voyager 1 is still alive and talking 32 years later and 0.0017 light years away.
Soylent
not rated yet Apr 19, 2009
It is destructivein the sense that we are placing hugely dangerous radioactive waste (35B tons per year per plant) into "safe" storage areas.


I have no idea what you're talking about. The spent fuel of a years worth of operation in a 1 GW nuclear plant could fit under my desk if you remove the U-238, which went through the reactor unchanged.
Fazer
not rated yet Apr 19, 2009
Birger, this University of Missouri page mentions 40% efficiency. So I think they are saying it would be comparable to conventional nuclear, but without generating as much waste heat.

https://mospace.u...0355/769

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