Nuclear power: The package inside this prototype betavoltaic battery contains layers of silicon carbide and metal foil embedded with the radioactive isotope tritium. When high-energy electrons emitted by the decay of tritium hit the silicon carbide, it produces an electrical current that exits the cell through the metal pins. Such batteries are designed to last 25 years.
Widetronix
Long-lived nuclear batteries powered by hydrogen isotopes are in testing for military applications.
Batteries that harvest energy from the nuclear decay of isotopes can produce very low levels of current and last for decades without needing to be replaced. A new version of the batteries, called betavoltaics, is being developed by an Ithaca, NY-based company and tested by Lockheed Martin. The batteries could potentially power electrical circuits that protect military planes and missiles from tampering by destroying information stored in the systems, or by sending out a warning signal to a military center. The batteries are expected to last for 25 years. The company, called Widetronix, is also working with medical-device makers to develop batteries that could last decades for implantable medical devices.
Widetronix's batteries are powered by the decay of a hydrogen isotope called tritium into high-energy electrons. While solar cells use semiconductors such as silicon to capture energy from the photons in sunlight, betavoltaic cells use a semiconductor to capture the energy in electrons produced during the nuclear decay of isotopes. This type of nuclear decay is called "beta decay," for the high-energy electrons, called beta particles, that it produces. The lifetimes of betavoltaic devices depend on the half-lives, ranging from a few years to 100 years, of the radioisotopes that power them. To make a battery that lasts 25 years from tritium, which has a half-life of 12.3 years, Widetronix loads the package with twice as much tritium as is initially required. These devices can withstand much harsher conditions than chemical batteries. This, and their long lifetimes, is what makes betavoltaics attractive as a power source for medical implants and for remote military sensing in extremely hot and cold environments.
The concept of betavoltaics is about 50 years old. The first pacemakers used betavoltaics based on the radioactive element promethium, but these betavoltaics were phased out when cheaper lithium-ion batteries were developed. The technology is now reemerging, says Peter Cabauy, CEO of another betavoltaic company, Miami-based City Labs, because semiconducting materials have improved so much. Early semiconducting materials weren't efficient enough at converting electrons from beta decay into a usable current, so they had to use higher energy, more expensive--and potentially hazardous--isotopes. More efficient semiconducting materials can be paired with relatively benign isotopes such as tritium, which produce weak radiation.
Widetronix's batteries are made up of a metal foil impregnated with tritium isotopes and a thin chip of the semiconductor silicon carbide, which can convert 30 percent of the beta particles that hit it into an electrical current. "Silicon carbide is very robust, and when we thin it down, it becomes flexible," says Widetronix CEO Jonathan Greene. "When we stack up chips and foils into a package a centimeter squared and two-tenths of a centimeter high, we have a one microwatt product." The prototype being tested by Lockheed Martin produces 25 nanowatts of power.
Betavoltaics aren't very powerful. They don't have nearly enough power to drive a laptop or a cell phone. But their energy density is high: they store a lot of energy in films just micrometers thick and can be made in very small packages. "We're focusing on places where you need a very long life and energy density," says Greene.
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Depend on kind of nuclear waste. If you asking abaut depleted nuclear fuel, yes, it is possible but would be expensive. Enrichment process is needed.
Secondary activated wastes - like gloves, tools, clothes and etc. (used by NPP workers)is inpossible to use as fuel.
Actually even enriched nuclear fuel would be useless for this technology. To see why, we must consider the actual obtainable power:
Whenever a radioactive atom decays and emits radiation, we have a chance (30% for tritium, quoted from the article) to change that into electrical charge. So an element like tritium, with a low half-life, decays quite quickly, producing a reasonable amount of power. Uranium however, has a half-life measured in billions of years. The amount of electrical power produced per unit time is therefore extremely low.
Mind you, if you wanted a battery to produce attowatts (10^-18 W) for a billion years, nuclear waste might come in handy. ;)
i agree but at the same time woutent shorting it to a year for publick use be more biabul it would contain less readio ative icatopes and brack dowen i do know that they have develuped a process to compleatley couse readoative deacay they could use this to power plasmacation witck is used to cous decay and
recuralate the system witch would solve all or the readio ative wast if we re use this decay
but at the same time readio ative decay is allso dangrous
While the decay products of tritium are safe, tritium itself is toxic. As an isotope of hydrogen, it can be incorporated into the body chemically, where its decay can produce damaging radiation. Presumably no tritium leaks or tunnels out of these batteries?
Tritium is chemically hydrogen, and thus easily and strongly bound to various kinds of surface including many metals. You could remove it if you try, but the passive safety within the multilayer foil sandwich should be good.
"silicon carbide ... can convert 30 percent of the beta particles that hit it into an electrical current"
I assume you mean that 30% of the incident beta particle energy is captured as electrical energy? Your phrasing might suggest that each incident beta particle, i.e. electron, on average produces .3 x 1.6 x 10^-19 amp-seconds of current.
I think what the author meant is that the conversion of captured beta particles is 30%, ie that all of the free electrons are absorbed in the silicon carbide layer, and 30% of those adsorption events create a unit of charge. The analogy useful here is solar cells - virtually all of the incident radiation (light in this case) is absorbed, but only some fraction of this radiation is converted to electricity.
It is more likely that all electrons reaching the SiC are absorbed, but only 30% are travelling in the right direction to get there. The tritium decays in all directions plus there will be some electric potential difference to deflect electrons not travelling "up" enough. The beta decay (according to Alpha) has an 18.6 kV potential so the charge difference across the gap should be quite large if they want to maximize efficiency. A tiny trickle of current at high voltage. But that voltage will turn electrons away if they are on shallow trajectories.
i know at one point they were exparatamenting with salt cooled nuckler genaratior but the salt wore dowen the pices and coused a magor dazaster coudent the put the layer that broke in a persherized cover ant this world fix the ware dowen problem as it is recycled throw sodim un like watter dosent lose heat as fast
they mete even be able to spin a turbine with liquid led sence it dosent tack readio ativity
why dont dont you a quntosomack antamiser in your phosonick resanator chamber
To answer your question about the nuclear waste: Yes, the vast majority of it, 95% of it can be reprocessed, and used again as fuel. This 95% includes The spent fuel, which is still contains about 2% enrichment, and the Pu-239 created from U-238 absorbing neutrons. Pu-239 is a ready fuel and easy to separate out, the Uranium fuel would have to be enriched, which isn't that hard, and in the future, fast reactors will be able to burn U-238 as fuel, or use it in a breeding process.
Another 2% of the waste, consisting of the Actinides, could be burned in a fast reactor, in the end leaving only about 2% of the total waste that would need to be stored, and that with future technology could be reprocessed further.
- Tritium
These "batteries" are actually radio-isotope generators. There is no chance of tritium leakage because the tritium atoms are embedded in the silicon carbide lattice. Yes tritium is very toxic, and while dead skin is enough to shield the body from beta particles, an ingested beta emitter can cause issues. However, tritium has been used for years in special lighting applications such as instrument displays, exit signs, ect.
Overall this is a pretty cool idea, and seems like it would be much more efficient than current radioisotope thermal generators (RTG's), however the life span isn't as long.
The title is a bit misleading, a nano-generator is a better description I think than calling it a battery.
Thanks for all this info spad12, but I want to point out a small detail--the tritium is embedded in a metal film layered with the silicon carbide, not in the silicon carbide itself.
Ohhh, ok, my mistake. The primary thing that I was trying to point out is that it doesn't exist in a gaseous state, it is embedded within another substrate, and thus significantly easier and safer to work with and handle.
Some of the commenters have asked about the safety of tritium. Tritium is already in a few products on the market for illumination including glowing green exit signs, watch hands, and gun sights. When beta particles from the tritium hit a phosphor that's mixed with the isotope, the phosphor emits visible light.
You can leave all of the Uranium and Plutonium isotopes in the recycled fuel - we use "recycled" soviet nukes to produce ~10% of our electricity.
The short half life alpha emitters are the most dangerous if ingested (polonium-210 poisoning of Alexander Litvinenko)
ATOMIC WEIGHTS OF THE ELEMENTS 2007
read more in this link
http://www.chem.qmul.ac.uk/iupac/AtWt/
why should you not stick a fosonick antimiser in a foconick resanator chamber
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3 Comments
nuclear waste?
Most nuclear waste is still very radioactive when it's dumped on a containment site. Could at least some of this waste be used for electricity generation?
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