What are Nuclear Batteries? Their types, advantages & disadvatnages

No doubt that each and every one of us frequently use batteries in our daily lives in a number of applications, like- lighting up a torch, playing with toys, using certain gadgets, and so on. But this nuclear battery is not your usual battery, it is rather quite different from them, so let us dive into its depths and try to explore all the hidden treasures of knowledge.

What is Nuclear battery?

A nuclear battery is a kind of equipment that utilises all the energy of a radioactive isotope which is decaying and as a result generates electricity. I know that a question might be arising in your mind that electricity is also generated by nuclear reactors, so what is the possible difference between these two boons of technology? Well, the answer is that our nuclear batteries generate electricity but do not involve chain reactions like that of nuclear reactors.

When compared with most of the other batteries, they are generally very expensive but do not just judge it by the price, as they have their set of advantages to offer. One of the biggest advantages is that they have a very long life cycle and are also very durable and suitable for rough and tough usage, where all the batteries fail to perform. They are the powerhouse of the Pacemakers, Underwater equipment, Spacecraft and Rockets, and also Remotely located space stations.

Let us now explore the isotopes that are used in it. It uses radioisotopes which generate very less energy beta particles and even alpha particles sometimes of fluctuating energies. This is so because the beta particles restrict the generation of massive energy-containing Bremsstrahlung radiation which if developed would need a super shielding mechanism. Therefore, the isotopes generally used here are- Nickel-63, Tritium, Technetium-99, Promethium-147, Curium-242, Plutonium-238, Strontium-90, and Curium-244.

As of now, all of you must have understood the basic meaning and the use of this battery, therefore, it is the time that we go on to explore it more and more. It is also known as Tritium battery, Radioisotope generator, and Atomic battery. Though it was discovered in 1913, it got the attention that it deserved in the 1950s, when it became the main source of powering the gigantic spaceships for carrying out all the space missions. Later on, it also brought a paradigm shift in the medical and health sector department and made its foot firmer and firmer in all the missions related to space.

Now, let me showcase you the structure of this powerful battery. A nuclear battery consists of thermal and non-thermal converters. The non-thermal converters are again divided further into three more categories, namely- direct charge batteries, direct conversion batteries and indirect conversion batteries. Furthermore, the direct charge battery is again composed of alpha and beta particles, and the direct conversion batteries include- p-n junction diode, contact potential, and secondary electrons. 

The main techniques of conversion in a nuclear battery are of two types:

1. THERMAL: In this type of technique, the power output is a function of temperature differential.
2. NON-THERMAL: In this type of technique, the power output is not a function of temperature differential.

Thermal Converters

The Thermal method of conversion generally includes- Thermionic converter, Radioisotope thermoelectric generator, thermophotovoltaic cells, Stirling radioisotope generator and alkali-metal thermal to the electric converter. So, we must know some brief details about them, here we go:

Thermionic converter

It includes a very hot electrode that releases electrons through a space charge barrier to a cooler electrode and this process, in turn, generates an essential power output. Caesium vapour provides a supply of ions to eliminate the electron space charge and it also further enhances the work function of the electrode.

Radioisotope thermoelectric generator

It employs thermocouples, which is formed from two wires of different metals. A voltage gradient from one end of the wire to the other end is made by the temperature gradient.

Thermophotovoltaic cells

They follow the same principles as that of Photovoltaic cells, but yes, there is one exception, which is the fact that they transform Infrared light, rather than visible light, emitted by a very hot source, into electricity. Not only this, but they also possess a little higher efficiency as compared to Thermoelectric couples and can be overlaid on thermoelectric couples, which simply doubles the efficiency.

Alkali-metal thermal to Electric Converter

It is more or less an electrochemical system and works as per the electrolyte used in sodium sulphur battery, sodium beta alumina. Its efficiency is roughly 20 per cent.

Stirling RadioIsotopr Generator 

It is powered by the temperature difference developed by a radioisotope. New changes have led to the development of a more effective version, called Advanced Stirling radioisotope generator.

Non-Thermal Converters

This method includes Direct charging generators, Betavoltaics, Alphavoltaics, Optoelectronic, and Reciprocating electromechanical atomic batteries. Now, let us study them in little detail.

Direct charging generators

It boasts of a capacitor, and the current of charged particles from a radioactive layer which is deposited on one of the electrodes charges this capacitor. The spacing here can be either dielectric or vacuum.

Betavoltaics

They are the generators of electrical current. It can also be considered as a type of battery that uses energy from a radioactive source releasing beta particles. Hydrogen isotope, Tritium, etc are some examples of common sources. It uses a non-thermal conversion method and employs a semiconductor p-n junction.

Alphavoltaics

These are the tools that make use of a semiconductor junction to create electrical particle from alpha particles.

Optoelectronic

A good example of this process is a beta particle that stimulates an excimer mixture and the light-induced would help to power a photocell.

Reciprocating electromechanical atomic batteries

It makes the best use of the charge build-up between two plates to pull one plate which is bendable towards the other plate. And this process goes on, until the two plates touch, discharge, and finally equalize the electrostatic buildup, and spring back. The generated relative motion among the two plates can now be used to produce electricity from a linear generator or with the aid of flexing piezoelectric.

Therefore, we have discussed in brief about nuclear batteries, so now let us know all about their advantages and disadvantages:

Advantages

1. The first benefit of Nuclear battery is its gigantic lifespan.
2. A very rough and tough, as well as a trustworthy means of generating electricity.
3. Massive amount of energy can be produced.
4. Waste produced is very less.
5. Produces very little that may lead to the greenhouse effect.
6. The fuel used here is the waste from nuclear fission.
7. The energy density is high.

Disadvantages

1. The initial cost is quite expensive.
2. Another disadvantage of Nuclear battery is the methods of energy conversion are not very much advanced or the ones based on the latest technology or pattern.
3. It is not very popular to gain the support and trust of the masses because of the word Nuclear that instils fear in mind.

Thus, this was all for the Nuclear batteries, I would now end this article by saying that it is indeed a very beautiful boon of technology to us, and it has made many of our dreams come true, and I hope and believe that it would continue to do so in the coming future with rapid advancements.

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You can also see the quick review of Nuclear battery available on Standford website.