Radioisotopes for Li betavoltaicas
betavoltaicas batteries are batteries that transform nuclear beta radiation directly into electricity usable.
Radioisotopes that can be used for these batteries must meet several requirements, including having an acceptable half-life (several years). If the half-life is very short, the battery will escasa.Por hand, if the lifetime is very long, we will need a lot of material to give us a current acceptable.
Another requirement, equally important, is that it is a pure beta emitter. Gamma radiation shielding required, making the heavier and larger battery. In addition, gamma radiation causing the electrons moving decrease of the final efficiency.
These batteries are extremely inefficient at the moment, but already sold some (not very powerful, of course) Tritium in BetaBatt .
They come in several forms: direct (using vacuum) through the dielectric, using PN diode, excimer mixture, resonant ... BataBatt are those of PN diode, or something, because the tritium is in contact with a pad of silica micro-perforado.De anyway, now do not plan to discuss the existing types of nuclear batteries. Without further
roll, here are a list of pros and cons of each radioisotope usable:
Tritium :
Tritium is a radioisotope of hydrogen with a half life of 12 years issued by a beta particle to 18 KeV.
+ Very safe.
+ There is a great experience with tritium handling.
+ is the most development takes years.
"It's expensive (2 / Ci)
" His weak radiation causes need to obtain 1 W 50000 Ci, and That's a 100% efficiency
.
"When the boom begins nuclear fusion will become so expensive that all companies that use Tritium
radioisotope will have to change if they want to exist.
Carbon-14:
It occurs in nature as it is formed by cosmic radiation steadily, generating 2.5 kg / year worldwide. Issues
156.4 KeV beta particles and has a half life of about 5715 years.
+ is found in nature in large quantities
+ power would allow for thousands of small devices.
"Very, very expensive. It is almost impossible to extract from nature, because the methods that exist are so inefficient that the C-14 only commercially developed in nuclear reactors.
Nickel-63:
is a metal that is obtained from the activation products from nuclear reactors. It has a half life of 100.1 years, and beta radiation is 66.95 KeV.
+ is easily obtained in large quantities.
+ solve some of the problematic of nuclear waste as it would be used and would not be buried and stored in pools.
+ Batteries have a long life.
+ has already been successfully tested and is sold electrlíticamente deposited on a metal plate.
+ Deposited in this manner, it is very difficult to introduction into the environment.
-Radiochemistry is very dangerous.
Krypton-85:
is a noble gas with a half life of about 10 years and emits beta radiation to 687 KeV. Good
+ half-life (not too short nor too long). + Radiation
powerful (To achieve Watt will need 40 times less than the Tritium Curios).
+ Chemically inert.
+ When gas, if leak if the amount is small is dissolved in the atmosphere to levels not dangerous.
+ Very cheap (0.20 / Ci, and in large amounts over the price is lowered). + Very efficient
excímers mixtures (Kr-85 + halogen). Ultraviolet light emitted can be exploited by nuclear battery, while the electrons (which have not been stopped) can be exploited in the traditional way (diode PN).
-cause third degree burns on the skin.
"If large amounts are inhaled, cause death in minutes by waterlogging of the lungs.
"His strong radiation damage of dielectrics and semi-conductors (inability to use such a battery directly BataBatt lasting more than 1 year without break). Danger
-gamma emission (half shield required.)
Strontium-90 :
is an abundant fission product. Has a half life of 30 years, and beta particles are of 546 KeV. But the decline, decay in Y-90, which is also unstable. It has a half life of 64 hours and beta particles are 2.2 MeV, which is much energía.Finalmente, Zr-90 decays, it is stable.
+ is able to generate much energy.
+ has already been used, but in thermo-generators, because the heat generated in large quantities.
+ Very abundant.
+ solve some of the problems of nuclear waste storage to be used.
+ Very cheap.
-The Y-90 emits gamma radiation.
-Radiochemistry very dangerous.
powerful -damaging radiation and semicontuctores dielectrics.
Promethium-147:
Rare Earth with 2.6 year half life and emits radiation at 224 keV.
+ is under investigation. Very promising. Good
+ half-life, perhaps little as needed.
+ Cheap (0.50 / Ci).
+ serves no biological function, making it safe.
+ easily Usable in any battery, its radiation does not damage the components.
"The problem of being solid, can be manipulated by terrorists to make a dirty bomb.
Well, so far the most usable. Of course, the end is going to impose the tritium, which look silly.
I see much future in Pm-147, which should be used along the Ni-63 to nuclear batteries. Never good to over-reliance on a single radioisotope.
The Kr-85 can also be used, provided it is well encapsulated and does not require much activity.
Salu2!
PS: I can not dismiss without recommending this great PDF on batteries betavoltaicas.
