Power Plant Works

How Nuclear Power Plant Works?
Working of nuclear plant resembles that of fossil fuel plants but differ in the on going process as the nuclear energy is generated in a nuclear reactor as a result of chain reaction. Rods of Uranium are dipped in the reactor and energy is produced by the process of nuclear fission. The neutrons are projected into the Uranium atoms, after striking with the nucleus the atom splits and generates large amount of energy. Water or some gas like carbon dioxide is pushed into the nuclear reactor which on heating used to generate electricity by running turbines. The turbines and generators of nuclear power plant are similar to conventional power stations. To control the nuclear chain reaction rods of boron are used to absorb neutrons. These boron rods are also used to slow down the chain reaction. The rods are dipped deep into the nuclear reactor to absorb neutrons which slows down the nuclear reaction. To raise the speed of nuclear reaction the boron rods are pulled out.
The power stations in Britain are planed near coasts. The location exempts the need of cooling tower as sea water can be used to convert steam into water. This water can be pumped into the reactor once again.

In a Magnox or AGR nuclear reactor, carbon dioxide is used to transport heat due to its qualities of being a good coolant and carry large amount of heat. The use of carbon dioxide also decreases the risks of fire because in high temperatures like 600 degrees Celsius the gas does not create trouble.

The construction of the nuclear reactor is very important because the flaws of structure can result into massive tragedies. Material must be selected by keeping in mind the internal temperature of the nuclear reactor and the compatibility of fuel because improper material can badly affect the environment. After the nuclear reactor is build up and starts to function there is no way to amend a mistake.

People are usually afraid of nuclear power plants but there is nothing to worry about because the reactors are not dangerous and explosive like atom bombs. Boron rods can control the increasing temperature of the nuclear rector if the rods do not serve the purpose than emergency control rods are used. These rods drop down in the reactor and shut the system automatically.


Note: This image explaining how nuclear fussion takes place to produce electricity.

Advantages of Nuclear Energy

There are many advantages of using nuclear fuel for generating nuclear energy. The usefulness is given below:

• Nuclear power does not cost more than the coal. So it is very easy and affordable to generate nuclear energy.
• The reaction does not produce pollutants or hazardous smoke of green house gases like carbon dioxide.
• The reactor is able of generating huge amount of energy by using negligible amount of fuel.
• The waste of nuclear reactor is negligible.
• It is one of the most reliable sources of energy.
• Nuclear power is reliable.

Disadvantages of Nuclear Energy
There are also disadvantages of nuclear energy some of them are given below:

• Although the waste is very small but it is more dangerous than the by products of many other fossil fuels. The residue needs to be buried deep down in earth for thousands of year so the radioactivity can diminish. It should also be kept safe from earth quake, floods and terrorist attack.
• The source of energy is although reliable but to maintain the safety of the plant is very expensive. In case of any accident, the nuclear power station can result into a disaster.

The nuclear energy is no doubt a very useful source to meet the energy requirement but it also create issues of mishandling. However, energy is the backbone of our society and there is no way to escape the every increasing need. It is also suggested that the states that use nuclear reactors to fulfill there needs must behave responsibly and discard the wastage properly.

  

from: http://www.solarpowernotes.com/non-renewable-energy/nuclear-energy.html

Nuclear Energy – Is it the solution for Malaysia?

Nuclear energy has been contributing to 15% of the world’s energy today as can be seen in Figure 1 Some nations rely heavily on nuclear, whereas others have a small proportion of nuclear in their total energy portfolio. France has the highest proportion of electricity produced by nuclear sources at a figure of more than 70%. Figure 2 shows the proportion of electricity generated via nuclear energy.  There seem to be about 30 countries around the world with nuclear reactors with total capacity of 372,000 MW[ However, many Asian countries are still lagging behind developed nations in terms of nuclear power. So, what are the contributing factors behind this slow adoption of nuclear power? In this article, we aim to look at the advantages and disadvantages of nuclear power and see how feasible is it to be applied in the Malaysian context. We will look at issues such as why countries are reluctant to adopt nuclear power and what fears do other countries have. To conclude, we will give an overview of possible actions that the government could take in Malaysia.

 
Figure 1: Composition of world electricity generation[1]

Figure 2: Percentage of electricity generated using nuclear power in countries that operate nuclear power plants

With many countries adopting nuclear power plants, clearly this technology has advantages. Nuclear power plants can provide a good base load of electricity because of its stable output. Base load is the minimum load that is demanded at any point in time. Above the base load, demand is not constant and tends to vary across time. Besides that, the operational costs of nuclear plants are cheaper at the current point in time relative to the prices of gas and coal used in the other power plants. As seen in Figure 3, the cost of electricity is relatively cheaper when using nuclear sources rather than fossil fuels. On top of that, it is a relatively clean source of energy with respect to greenhouse gas emissions which helps certain governments to meet their carbon emissions reduction targets. With many nations having signed the Kyoto protocols, emissions level has to drop to match the level in the year 1990 and nuclear power can potentially contribute towards meeting that target.

Figure 3: Relative prices of US electricity production costs

Having looked at the advantages, we now explore the downside of nuclear power. The costs of building and commissioning a nuclear plant are very high. Due to this, investment rarely occurs if there isn’t any backing from the government in terms of guaranteed financial support or guaranteed contracts granted. Besides that, a proper waste management system needs to be incorporated as nuclear waste is harmful. This requires proper knowledge and experience in management and operation. There are two ways of going about this. For short term purposes, importing expatriates with the right skill sets can do the job. But in the long term, it is necessary to train people locally in order to sustain locally operated nuclear power plants. These are all additional costs that can make the whole project very expensive. Another disadvantage is that nuclear power plants usually operate in the base load mode and seldom change their level of output. This is especially true for the older reactors where any change in output takes a long time to come into effect. However, the modern reactors can change at a faster rate, albeit at a higher cost.

In order to determine the feasibility of nuclear power plans in Malaysia, we need to understand the local scenario. First of all, why didn’t we have nuclear plants in the past? A few analyses in the 70s and 80s were carried out, but the Malaysian Board of Energy, Tenaga Nasional Berhad (TNB) decided to build more gas plants following the rapid expansion of the oil and gas field. Now that gas prices are soaring, nuclear seems like a pretty good alternative. Another reason for sceptics to discount this source of energy at that point in time was due to two major nuclear power incidents in Three Mile and Chernobyl. The protocols for operating a nuclear power plant are usually very strict and rigid. The common cause of these two incidents is human error. Hence, stringent guidelines and multiple layered of checks and audits should be in place to avoid similar occurrences.

There is a lot of fear surrounding the topic of nuclear. Many associate nuclear with the possibility of building nuclear weapons. What is the difference of nuclear power plants and nuclear weapons? For the former, the uranium only needs to be enriched by 2-3%. The latter however, needs around 90% enrichment of the uranium and can potentially be used as a lethal weapon of destruction. It has been frequently reported that the US government is against Iran’s plan to build nuclear power plants due to fear of terror activities. Worldwide bodies such as the World Nuclear Association should create stringent, but standard rules for all countries in order for everyone to be governed by a neutral body to avoid international conflicts.

Nuclear power is clean, reliable and relatively cheap in the long run. The reliability in terms of the security of supply exists currently. However, with many more power plants being built, demand might increase and shortages of uranium might occur. This might drive up the price of nuclear-produced electricity, making it less attractive. There isn’t a single way forward but it is important that we know what are the advantages and disadvantages of nuclear power, before investing in it. The Malaysian Electricity Board should run a scenario analysis to investigate the feasibility of nuclear energy based on a range of factors, namely capital and maintenance cost, future costs of uranium with respect to other inputs, i.e. gas and oil as well as the world nuclear outlook. Decisions whether to invest in this technology needs to be made fast in order to get the ball rolling. With average building and commissioning time exceeding 10 years, we need to decide and build whilst making sure we do get enough stock of uranium. One problem that can be foreseen is a ‘dash for uranium’ in the future as happened in the 90s when the UK experienced  a ‘dash for gas’ when prices were low.

Reactor Building Layout and Reactor Design

The boiling water reactor (BWR) is a type of light water nuclear reactor used for the generation of electrical power. It is the second most common type of electricity-generating nuclear reactor after the pressurized water reactor (PWR), also a type of light water nuclear reactor. The BWR was developed by the Idaho National Laboratory and General Electric in the mid-1950s. The main present manufacturer is GE Hitachi Nuclear Energy, which specializes in the design and construction of this type of reactor.

The first generation of production boiling water reactors saw the incremental development of the unique and distinctive features of the BWR: the torus (used to quench steam in the event of a transient requiring the quenching of steam), as well as the drywell, the elimination of the heat exchanger, the steam dryer, the distinctive general layout of the reactor building, and the standardization of reactor control and safety systems. The first, General Electric, series of production BWRs evolved through 6 iterative design phases, each termed BWR/1 through BWR/6. (BWR/4s, BWR/5s, and BWR/6s are the most common types in service today.) The vast majority of BWRs in service throughout the world belong to one of these design phases.

Practical Applications of Nuclear Fission

Nuclear reactor is a furnace or an equipment in which the nuclear chain reaction is carried out in a controlled manner and the heat energy so liberated is converted into electricity.

Boiling Water type Nuclear Reactor

Control Rods

To control the fission reaction, rods made of cadmium or boron is suspended between the fuel rods. These rods can be raised or lowered and thus check the reaction by absorbing the right number of neutrons. Hence they are called control rods. When the control rods are completely inserted into the fuel, i.e., inside the reactor all the neutrons are absorbed and the reaction does not start.

These rods are then slowly raised till they absorb the right number of neutrons and thus leaving behind just enough neutrons to sustain the chain reaction. That is, when the control rods absorb two neutrons leaving behind one neutron to bring about further fission reaction we say that the reactor has attained criticality. At this stage number of atoms getting fissioned in one second is constant which means that energy is generated at a constant rate

Moderator

The speed of the neutrons produced during the fission reaction has to be slowed down so that the neutrons are in contact with the fuel rods for sufficient time to bring about fission reaction. This is done by surrounding the fuel rods with graphite or heavy water. The material used to slow down the speed of neutrons is called a moderator. A moderator should absorb as few neutrons as possible and also slow down the neutron 

Coolant

The heat released during the fission reaction is carried away by liquid sodium or heavy water. The coolant enters from the base of the reactor core and leaves at the top. The heat carried away by the coolant is used for producing steam and the coolant is pumped back into the reactor core.

 Shielding

 The whole reactor core is covered with a thick coat of radiation absorbent material like lead and is enclosed in a heavy concrete or steel dome. This is done to protect the workers from dangerous radiations.

Nuclear Reactor:A Radioactive Waste-Making Machine.

Here are the reactor designs shown in the article from the 1950's:

 

The above images are from a magazine article about nuclear power, probably 1956. (We have not been able to determine which magazine the images are from. Perhaps Life, Look, etc.. Any assistance in positively identifying this source will be appreciated!)

Below are several schematic diagrams of a Boiling Water Reactor Pressure Vessel. This unit is about four stories tall:

The above image is from a Nuclear Mafia web site.

-- The above image is from: The Silent Bomb: A Guide to the Nuclear Energy Controversy, Edited by Peter Faulkner, page 85,Vintage Books, NY, July, 1977 (colorization by this author).

Below is a schematic drawing of a GE BWR:

-- The above image is from: The Silent Bomb: A Guide to the Nuclear Energy Controversy, Edited by Peter Faulkner, page 283,Vintage Books, NY, July, 1977 (colorization by this author).

The reactor cores remain radioactive for about a million years after their brief use in the reactor (two to six years). The waste must be carefully isolated from humans and other living things during this entire time. NO EXCEPTIONS.

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Below are schematic diagrams for PWR and BWR reactors, the two types used in the United States:

-- The above image is from: The Bridgeport (Connecticut) Telegram, April 30th, 1980, page 38 (colorization by this author).

Many ideas for how to safely store the waste have been suggested, but none have been successfully implemented, and none solve the problem of transportation accidents along the way to the final repository, whatever it might be.

-- The above image is from: Northeast Utilities (Connecticut Yankee) Information Brochure, June, 1973, pages 10-11 (adjusted for the Internet and additional colorization by this author).

from:http://www.animatedsoftware.com/hotwords/nuclear_reactor/nuclear_reactor.htm