April 11, 2021

I, Science

The science magazine of Imperial College

Nuclear power and weapons have fascinated man since they were first developed. While controlled fission has brought many advantages to humanity it has been our natural tendency to focus on its destructive possibilities. Are they, however, as big a threat as people imagine? Or have they been overhyped?


The atomic bomb is usually what first comes to most people’s minds when one mentions nuclear threats. Such weapons are indeed frightening. A one megaton warhead, a not uncommon yield, can create a milewide fireball. Its destructive range would extend far further, with the shockwave created by displaced air able to flatten distant buildings.  The  wave of intense heat given off by the fireball would also cause horrific burns. A ten megaton warhead would be able to completely destroy the majority of central New York, including most of Manhattan. This was a real fear during the Cold War, with the USSR and USA having enough bombs to obliterate all of one another’s major cities. Although the Cold War is over, the threat of nuclear destruction is still very real. Israel, a country surrounded by enemies, has been secretly developing nuclear weapons almost since its foundation, while India and Pakistan, two antagonistic neighbouring states also have nuclear capabilities. Fortunately, neither of these situations appear to be threatening enough to indicate that nuclear war is either imminent, or even likely. However, the chance of it happening still remains, especially with rogue and unpredictable states, such as North Korea and Iran, showing signs of developing their nuclear programs.


We also cannot count out the threat of terrorists. While they may not have the resources to build a complete nuclear bomb, many groups could very well be planning to use a ‘dirty bomb’. This would use conventional explosives to disperse highly radioactive material, such as enriched uranium or waste from nuclear power stations over a very large area. This material could cause death through radiation sickness and greatly increase the risk of cancer in later life for those who survived. The material required for such a device is surprisingly easy to find. While the countries of the former Soviet Union are infamous for their lax control of their nuclear materials other nations are not completely free from blame either.

Law enforcement agencies are working hard to prevent dangerous material getting into the hands of the wrong people, but the International Atomic Energy Agency believes that smuggling of such materials is widespread, and up to 85% of it goes undetected.


There is also a threat closer to home, in the form of accidents involving nuclear energy. Nuclear power stations have reactors filled with fuel rods containing U-235 atoms. When the nuclei of these atoms absorb neutrons, they split in a process known as nuclear fission, releasing a lot of energy and more neutrons, which can go on to cause further fission. A coolant then takes the heat energy produced by this reaction away to a heat exchanger, where water is turned into steam, and used to drive the turbines of an electricity generator. Nuclear reactors have many inbuilt safety features, including control rods to absorb excess neutrons and thick concrete walls to prevent the escape of radioactive material.
However, these have been known to fail; most spectacularly in the 1986 Chernobyl incident in the Ukraine. Fuel rods overheated after the power plant’s operators turned off, or removed many key safety features for testing.

This resulted in a lack of cooling, and a dangerously high rate of fission within the reactor. What coolant there was evaporated, resulting in a pressure build up that broke through the reactor’s walls. Large amounts of radioactive material were spread over the neighbouring countryside and towns, causing about 100 nearby settlements to be permanently abandoned. People are still suffering as a result of the radiation they absorbed, and it is estimated that 17,000 people overall will die due to Chernobyl.

This accident, however, was due to human error. Better training could ensure that something like it never happened again. As early as 1973, the US Atomic Energy Commission estimated that, with proper safety procedures, the country could expect only one major accident every 10 million years. Engineers have recently designed new types of reactors, in which it would be impossible for the fuel to get hot enough to breach the reactor walls, further improving safety.

We do certainly face nuclear threats. But they are not as big or insurmountable as often reported. We must be vigilant but at the same time there is no need to overreact.  Some questions may remain over weapons, but nuclear power almost certainly doesn’t spell doom for the human race.