What Is Nuclear Power

Published Date: 02 Nov 2017

Issues Investigation

SACE STAGE 2 PHYSICS

Brian Le

http://static.guim.co.uk/sys-images/Guardian/Pix/pictures/2008/03/21/nuclear10b.jpg

2013

Brian Le

BPS

1/1/2013

Introduction:

Living in the year 2013, the developing world and its advancing technologies are reaching further beyond the dreams of what the people of the past generations could have hoped for. The past century has seen achievements and discoveries that will possibly save the world’s depleting source of fossil fuel energy. As the world continues to develop, its fossil fuel usage will increase exponentially[6]. The upcoming centuries will see the inevitable decline of our primary fuel source, fossil fuels. With the decline of fossil fuels being inevitable, the world is slowly making its transition to newer and more efficient methods of creating energy[6]. One such development has been nuclear power. It is renewable, clean for the atmosphere and creates much more energy than fossil fuels[6]. The debut of Nuclear Power has been one of the biggest impacts the world has experienced in the energy production industry, but as nuclear power is still being developed, there are risks and negative factors the come with the use of it. As the fossil fuel sources decline, will the world have to face these risks and make the transition to it anyway?

http://i.telegraph.co.uk/multimedia/archive/02203/nuclear_plants_2203199b.jpg

Source: http://i.telegraph.co.uk/multimedia/archive/02203/nuclear_plants_2203199b.jpg

New Source of Energy:

So what is ‘Nuclear power’?

In the recent years, there has been a global argument about the uses of the energy source called ‘nuclear power’. The way the media presents nuclear power today often gives two straight forward perspectives of it: "it’s either good or bad". Realistically nuclear power has its positives and its negatives. Nuclear has proven itself to be a very destructive energy source, due to the disaster possibilities, but it has also been proven to be a possible everlasting source of clean energy.

How does it work?

When explaining how nuclear energy is released, the process can be simplified to a logical sequence of steps (See diagram below) [4]: C:\Users\Brian\Desktop\Nuclear_Fuel_Cycle.png

Mining the ore

Mineralisation

Conversion and Enrichment

Nuclear Fission

The image shows the processes that Uranium goes through in order to produce nuclear energy. [4]

Source: http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Introduction/Nuclear-Fuel-Cycle-Overview/#.UXdX2bXil31

Mining, Mineralisation and Conversion and Enrichment

The desired metal for a nuclear reaction is Uranium[4]. There are areas around the world where uranium concentration is high enough for it to be extracted and used a nuclear fuel, for example South Australia. These concentrations of uranium are called ore[4]. Theses ores are mined, the extracted uranium is processed to separate it from other minerals and then it is enriched so that it is prepared to be put into rods for fission[14]. Uranium exists as a yellow powder called "Yellowcake" before it is exported, sold and used in power plants[4]. http://www.acfonline.org.au/sites/default/files/images/rich_page/main/be-informed-northern-australia-nuclear-uranium-mining-ranger_0.jpg

Uranium mine in Australia

Source: http://www.acfonline.org.au/sites/default/files/images/rich_page/main/be-informed-northern-australia-nuclear-uranium-mining-ranger_0.jpg

Nuclear Fission

A ‘nuclear fission’ is an exothermic nuclear reaction or a radioactive decay process [3] where the nucleus of an atom is split into two smaller parts to make two lighter nuclei, with the release of free neutrons, photons and a very large amount of energy[1]. Once nuclear fission occur the released neutrons which may trigger another reaction with another molecule and the process repeats. Nuclear fission can either be controlled, for uses like in nuclear power plants, or uncontrolled, like nuclear weapons (see diagram below)[1].

<= Chain nuclear fissions:

Source: http://www.atomicarchive.com/Fission/Images/chainreaction.jpg

http://www.atomicarchive.com/Fission/Images/chainreaction.jpg

In a large nucleus, the nucleon force acting over short distances is unable to overcome the repulsive electrostatic force between protons[1]. When this large nucleus captures a low energy neutron, it becomes excited and may elongate. The nuclear fission of a uranium-235 nucleus is triggered by the absorption of a low energy neutron into its large nucleus[2]. When this absorption occurs, the U-235 (Uranium-235) nucleus briefly turns into an excited U-236 (Uranium-236) nucleus with the energy provided by the neutron and the energy from the forces that bind the neutron[2]. The nucleon force of the U-236 nucleus is weakened and the electrostatic repulsive forces cause the nucleus to split into two[2]. The products of this reaction are Ba-142 (Barium-142) and Kr-91 (krypton-91), 3 free neutrons and one or more ‘prompt gamma rays’ (See equation below). In a nuclear fission reaction, the total mass of the reactants is greater than the mass of the products. The amount of mass that did not carry through to the products is converted into energy. This is shown in Einstein’s equation, E=∆mc2, [6] where E is energy, m is mass and c is the speed of light in a vacuum[1]. It is through the defect of mass that the energy is released during the nuclear fission of uranium-235.

Equation for Nuclear fission reaction

Nuclear fission of a Uranium-235 nucleus.

Source: http://www.mdc.edu/kendall/chmphy/nuclear/images/fission.jpg

http://www.mdc.edu/kendall/chmphy/nuclear/images/fission.jpg

How do the power plants work?

In nuclear power plants, rods of uranium-235 are used as the heat source for heating water. The rods are lowered into the core of the reactor vessel which is surrounded by water[17]. The uranium-235 rods can only absorb low energy neutrons to undergo fission[17]. However in the reactor vessel, the neutrons emitted are of high energy level[17]. The energy level of neutrons is lowered by the collisions with other particles and energy transfer to the moderator. Heavy water is the moderator in reactor vessels, as it is low in mass and does not absorb neutrons[16]. Once the neutrons are of low energy level, they can be absorbed to create the chain fission reactions for heat energy. Control rods are used to control the rate of fission[17]. Control rods are made of elements that are capable of absorbing neutrons, but will no fission themselves[17]. By absorbing neutrons, control rods are able to control the number of fissions that occur. Once fissions occur, the energy created produces heat for water to boil and produces steam to rotate the turbines hence creating electricity[17].http://nerdtrek.com/wp-content/uploads/2011/03/Nuclear_Plant.gif

Source: http://www.45nuclearplants.com/images/Nuclear_Plant.gif

Pros and Cons

Nuclear power has many benefits. The world today is faced with many problems to do with climate change and global warming due to our current primary energy source, fossil fuels[5]. With the release of fossil fuel energy, comes high emissions of carbon dioxide into the atmosphere[21]. Nuclear energy is known to emit low amounts of carbon dioxide and does not produce carbon monoxide, which counters the problem[5]. Some may argue that energy sources such as solar power and wind power are a safer solution to this problem, but as mentioned by Barry Brooks in The Advertiser, "they have severe limits that often go unacknowledged." He also states, "Nuclear power offers an incredibly concentrate source of energy" [21], which leads to the next benefit of nuclear power, its energy production. The nuclear fission of a gram of uranium-235 can produce several hundred million times more energy than burning a gram of fossil fuels or coal (see table below) [7]. This would also mean that the impact on the environment due to mining would be much less severe, as not as much uranium would need to be mined to produce the same amount of energy per kilogram as coal or oil[7].

Fuel Type

Energy Density (kWh/kg)

Nuclear Fission (100% U-235)

24,513,889

Natural Uranium (99.3% U-238, 0.7% U-235) in a fast breeder reactor

6,666,667

Enriched Uranium (3.5% U-235) in a light water reactor

960,000

Natural Uranium (99.3% U-238, 0.7% U-235) in a light water reactor

123,056

LPG propane

13.8

LPG butane

13.6

Gasoline

13.0

Diesel fuel/Residential heating oil

12.7

Biodiesel oil

11.7

Anthracite Coal

9.0

Water at 100 m dam height

0.0003

Source http://nuclearfissionary.com

The table above presents the energy densities of nuclear power in comparison to various fossil fuels[6].

On the other hand, nuclear power does have its very destructive cons, and those opposing it argue that despite its efficiency, these significant danger risks are not worth taking[12]. Starting with its less destructive cons, the disposal of nuclear fuel waste will be a big problem[12]. Disposing of fuel rods will be difficult as these waste materials have a half-life of up to 4.5 billion years[20] and will take extremely long to decay[12]. The mining of Uranium is also hazardous and it is costly to do[12]. Other issues include the leakages and explosions[20] to do with the nuclear material. Its radioactivity also causes mutations and cancerous diseases to anything that comes in contact with it[12]. These devastating effects are shown in the aftermath of the nuclear catastrophe, the Chernobyl explosion, which was the most devastating nuclear accident in history. Not to mention the destructive power of the explosion itself which was "equivalent to that of 200 Hiroshima and Nagasaki bombs," and resulted in "thousands of fatal illnesses" (Lovgren, National Geographic News 2004). This nuclear explosion happened by accident, imagine if it was targeted by terrorist or hit by a natural disaster, like in Fukushima not too long ago.

Site of the Chernobyl power plant after the catastrophe

Source: http://tour2chernobyl.com/images/Chernobyl.jpg http://tour2chernobyl.com/images/Chernobyl.jpg

Recent studies have shown that these issues have been addressed and research is developing to make the use of nuclear power safer[18]. There is currently the development of a "hybrid nuclear fusion-fission" which involves the hybrid of the normal nuclear fission and nuclear fusion[18]. This "minimizes the environmental impacts, reduces risks, enlarges reserves of nuclear fuel and is more flexible to operate" (Hunt, J NewScientist 2010) [18]. This possibility is still being developed as it requires the development of a reactor core that is strong enough to withstand intense bombardment from energy neutrons[18].

So will we eventually have to take the risk of nuclear power as our fossil fuels decline regardless of risk? The probable answer as of right now is yes. Considering the factors like the rate at which nuclear fuel is being developed and the rate at which our fossil fuels are declining, we expect to see the end of our fossil fuel sources in the upcoming century[12]. Possibilities of our technology development opening more sources of fossil fuels is not very promising[12] but the development of safer nuclear power looks to be the way to go. Nuclear power is still under development and can still be evolved much more to be safe, everlasting and environmentally friendly[12]. Jumping hastily into the nuclear fuel industry would be foolish. Giving time for its development would be the best option. If nuclear energy is accepted without additional research and caution, "every man, woman and child lives under a nuclear sword of Damocles, hanging by the slenderest of threads, capable of being cut at any moment by accident or miscalculation or by madness" (President John Kennedy, 1961).