Research on nuclear-powered propulsion for ships began in the 1940s, ushering in the “atomic age”. Since then, only six countries have owned and operated nuclear submarines: China, France, India, Russia, the United Kingdom, and the United States.
Given the fact that Australia just tore off a contract for the construction of traditional submarines worth A$90 billion ($66 billion), the announcement of the recent deal may come as a surprise to many.
So what aspect is the phrase “atom” in atomic submarines talking about? First of all, it should be said that a nuclear-powered submarine is not a nuclear weapon, More simply, their appearance is no different from other submarines, except that they run on atomic energy.
In the early days of atomic research, scientists quickly realized that the enormous amount of energy produced by “fission of the nucleus” could be used to generate electricity. . nuclear reactors inside power plants have been used to power homes and many manufacturing industries around the world for 70 years. Similarly, each nuclear submarine is powered by a mini-reactor built into it.
At the centre of each atom is its nucleus, made up of protons and neutrons. The number of protons determines the chemical element to which the atom belongs; Nuclei that have the same number of protons but different numbers of neutrons are called isotopes of that element.
Some very heavy nuclei are susceptible to a process called fission, in which they split into two lighter nuclei with less total mass than the parent nucleus. The rest is converted into energy. The energy emitted is extremely large, as, in Albert Einstein’s famous equation, E= mc², where the energy produced is equivalent to the change in mass times the square of the speed of light.
Nuclear reactors on nuclear submarines are usually fueled by uranium. Natural uranium is mined mainly as an isotope called uranium-238, mixed with a small amount (0.7%) of the isotope uranium-235. For the reactor to work, the uranium fuel needs to be “enriched” to contain a certain percentage of uranium-235. For nuclear submarines, this ratio is usually 50%. The level of enrichment is a key factor in maintaining a chain reaction to a continuous and safe source of energy.
Inside the reactor, uranium-235 is bombarded with neutrons, causing some of the nuclei to undergo fusion. As a result, more neutrons are released, and this process continues in what is known as a “nuclear chain reaction”. The energy generated in the form of heat can be used to drive turbines to generate electricity, helping to power the submarine.
Advantages and disadvantages of nuclear submarines
One big advantage of nuclear-powered submarines is that they don’t need to be refuelled. When a nuclear submarine went into service, it was supplied with enough uranium fuel to last for more than 30 years.
The high efficiency of nuclear power also allows submarines to run at high speeds for a longer period than diesel/electric powered submarines. Furthermore, unlike internal combustion engines, nuclear reactors do not require air. That means that nuclear submarines can stay submerged underwater for months at a time, giving them better “stealth” and allowing them to engage in long-duration missions,
Their weakness is simple: Cost. The cost of building each nuclear submarine is often up to several billion dollars and requires a team of workers with high expertise in atomic science.
Thanks to the world-class training programs offered by leading universities and government agencies, Australia is meeting the growing needs in this sector, and will also benefit from experience and techniques shared by the US and UK through the new agreement “Aukus”.
At this stage, details of where Australia will source uranium fuel remain unclear. Although Australia has abundant uranium reserves, it cannot afford to enrich uranium, so it may have to import nuclear submarine fuel from abroad.
Atomic submarines are not nuclear weapons, of course. For uranium to be considered “weapons-grade,” it needs to be enriched to 90% uranium-235.
After all, Australia has never built a nuclear weapon before, and it is also a signatory to nuclear non-proliferation treaties and international export control mechanisms, which includes the Treaty on the Non-Proliferation of Nuclear Weapons and the Nuclear Nonproliferation and Disarmament Initiative.
The strategic advantage that nuclear submarines bring is the ability to “stealth” and pin targets secretly without being detected.
Maintaining safety, both for the crew and the natural environment is also critically important. Many Hollywood movies, such as “K19: The Widowmaker,” about a nuclear submarine that malfunctions on its maiden voyage, have made many people aware of the dangers posed by radiation.
However, modern safety controls and strict procedures today have greatly reduced the risk of nuclear submarine accidents, compared to the past.
Australia’s recent policy decision is still unclear what results in it will bring to them in terms of geography and strategy But they have shown a determination to pursue atomic science.