Today’s society consumes more energy than ever, and energy demand will continue growing as bigger, better and faster technologies are introduced. Energy consumption rate has risen by over 50% in the past 20 years. The pressing issue here is that renewable energy sources (solar, wind, hydro etc.) are not providing sufficient energy to meet demand and non-renewable sources (Coal, Crude Oil etc.) are inevitably coming to an end. Furthermore the production of greenhouses gases impacts the climate thus further complicating matters and adding to the problem. Therefore, there has never been a more crucial time for the utilisation of nuclear energy. This type energy is generated as a result of controlled nuclear reactions i.e. nuclear fission, and can be used in various ways, be it in reactors or even in bomb making!!
In order to understand the impacts of nuclear energy, it is useful to first explore its history and how it was received by the general public. This will build a good foundation to allow analysis of recent issues and problems presented by nuclear energy, exactly what caused these problems and how harmful or disastrous they could be. Once the problems are recognised, it is vital that they be addressed, after detailed investigation, with solutions such as suitable waste immobilisation. It will also allow for discovery and evaluation of the great benefits nuclear energy introduces and the great impact this has on the economy and the environment. In this Nuclear blog I aim to discuss and investigate nuclear energy as a replacement energy source as well as how it can be coupled with renewable energy to meet the economic constraints of today’s society and most importantly how the waste it produces can be immobilised efficiently. It will also explore how, over history, nuclear energy was manipulated in the production of nuclear weaponry i.e. the atomic bomb.
To get things rolling I want to start this blog with a report on the brief history of nuclear energy. Nuclear energy dates back to late 1800’s. To be exact ionising radiation was discovered by Wilhelm Rontgen in 1895 producing continuous x-rays by passing an electric current through an evacuated glass. Progressive steps were taken in the research of radiation until 1902 when Ernest Rutherford illustrated that radioactivity creates a different element by emitting an alpha (2 protons & 2 neutrons) or beta particle (an electron) from the nucleus. To understand how this works let’s look at an atom of nitrogen.
The yellow spheres are the protons, and the orange spheres are the neutrons, combined they form the nucleaus and give the atom its mass number (mass number = protons + neutrons). Nitrogen contains 7 protons (carrying a positive charge) and 7 neutrons with a mass number of 14. The 7 small white spheres orbiting the nucleas in shells are the electrons (carrying a negative charge). These numbers characterise the nitrogen atom, therefore if they are altered there would be changes in the element. Using this research Rutherford illustrated, in 1919, that all the particles fired from a radium source into nitrogen could form oxygen as a result of the nuclear rearrangement. He fired alpha particles (2 proton & 2 neutrons) at the nitrogen atom, this in turn increased the amount of protons and neutrons in nitrogen from 14 to same amount as in an isotope (an atom of an element with the same number of protons but different number of neutrons) of oxygen, and thus the element was converted from nitrogen to oxygen.
In the 1930s research accelerated and scientists were experimenting with bombarding atoms with protons and neutrons in order to create artificial radionuclides. It was also illustrated that upon bombardment of the nucleus with the neutron, the neutron is captured causing severe vibration and leading the nucleus to split into two not quite equal parts thus releasing significant amounts of energy. This is called nuclear fission and it was discovered this fission reaction could release further more neutrons which in turn would lead to more fission resulting in a vast amount of energy being released. Since its discovery nuclear energy, used with bombs and reactors, has been received with great controversy. It is associated with mutation, atomic weapons and universal doom. It is a prime example of irrational public fear of a misunderstood technology. This is illustrated by a recent survey undertaken in America and Japan showing that reactor accidents evoked more feelings of dread amongst the public than any other modern risk, including problems that harm millions of people annually. Also in the early days nuclear scientists were seen as alchemists due to the misunderstanding of the transmutation capabilities of nuclear science. This misunderstanding led to the labeling of nuclear energy as the ‘elixir of life’ in the early 20th century. Such an ideology was reinforced by the discovery that radium was useful in treating certain types of cancer, however the press reported that radium was capable of fully conquering all types of cancer (media hype). By the 1930s radium was included in pastes, powdered pills, tonics and even mineral waters to cure baldness, restore youth etc. However the public eventually came to learn that radium has as much chance of causing mutations and cancer as treating it. Up until this point nuclear energy was only seen to be useful for medicinal purposes, however over the late 20th century nuclear fission energy was harnessed and used in several ways, with the main use being in the nuclear fuel cycle delivering the nuclear energy we know today. Nuclear fission occurs when a heavy atomic nucleus breaks into smaller pieces (decay) releasing energy. This process can also be accelerated by bombardment of the nucleus with neutrons. Let’s take for example uranium, the most stable isotope has a mass number of 238 (146 protons + 92 neutrons) and is the slowest decaying. Uranium 235 decays slightly faster, however is still relatively stable. If we were to bombard U-235 with neutrons, the neutron would attach to the nucleus and form U-236, a very unstable isotope. This decays rapidly into an atom of barium and krypton. This is called induced fission. This is illustrated in the diagram below.
Bombarding a Nucleus with a Neutron to create Induced Fission
Nuclear scientists manipulated this energy and began using it in nuclear reactors. In 1951 the Experimental Breeder Reactor illustrated electric power can be generated from a nuclear source demonstrating the possibility of breeding plutonium. It was also illustrated that the water in reactor can be left to boil thus generating steam directly. However there was scepticism regarding the dangers of the instability associated with the boiling. As a result BORAX tests were undertaken to show that boiling reactors can operate safely and as a result further work was implemented illustrating electrical generation in 1955. This resulted in the commercial manufacture of boiling water reactors with the first being put into operation in Illinois, USA in 1960. Research in the USA led to the discovery of the pressurised water reactor with the first being used to produce commercial electric power at Pennsylvania USA in 1957. These reactors have been enhanced and improved through the year up until today, to produce the nuclear energy we know and hate/love (?).