The back-end of nuclear fuel cycle

Nuclear power is a gift to the human kind. Why? Because of the amazing fact that the nuclear fuel is renewable. It is renewable in a sense that it can be recycled over and over again. Can you recycle back coal? oil? gas? For that reason alone, nuclear power is special.

The used fuel or nuclear waste from a single 1000 megawatt nuclear plant that has been operated for 40 years is equal to energy of 130 million barrels of oil or 37 million tons of coal. Can you imagine that?

Used fuel rods can be process to remove the high radioactive fission products and separate the fissionable U-235 and plutonium. Plutonium can be used to make a mixed-oxide fuel (MOX) which is being used in reactors all over Europe. With new developed technology, all of the spent fuel can be made usable. It means no radioactive waste.

With this we can continue to develop nuclear fuel as a source of electricity and there is no limits to what we can achieve. Not to mention, with a cheap and clean source of power we can help to save our planet in the process. What good if we have all the electricity in the world  but we don't have a a planet to live on.

In the future, as the world experience shortage in fossil fuel, plutonium will be more valuable as fuel for nuclear reactors than as weapons of mass destruction. Imagine a world where nuclear is only use for power generation.

So we as the future of our generation, must take matters with our own hands. Who are they to deny our rights for clean and cheap energy. It is us who will lead this country. Support nuclear in our country. Help reduce the emission of C02. Save our planet. For the future of our own country. Say yes to nuclear power. Say yes to our future.

Nuclear Safety in Malaysia

From safety point of view, yes it is safe to build a nuclear power plant in Malaysia.

We need a large amount water to run the power plant. Malaysia is surrounded by the strait of Malacca and the South China Sea. Most power plant in the country are situated near the shore because sea water is abundant and free. Following the same trend, it is expected for the country's first nuclear plant to be close to sea. Since the water used in the plant does not contain any form of radiation contamination, it can be recycle back into sea. The only problem with that is the temperature water. The water that will be channel back into the sea will be a few degrees higher causing the surrounding body of water to warm up. Careful consideration must be put in the planning to avoid any marine life disaster.

"Thermal discharge from the Third Nuclear Power Plant is behind the rapid destruction of Kenting National Park’s coral reef, a marine researcher said, warning that the reef’s disappearance would jeopardize the fishing industry and ecosystem. " taken from http://www.taipeitimes.com.

The new plant could rectify this problem by cooling the water before channeling it back to sea. Extra heat exchanger or heat extractor could be put in place to reduce the water temperature. This is to ensure that the surrounding body of water near the power plant will not be heat up.

Picture of people swimming at Nanwan beach, with the No. 3 nuclear power station looming above. taken from http://www.smh.com.au/news/travel

"Uniten" We Stand, Divided We Fall

from right: Khairi , Hazwan, Anizam and Saiful

Government of Malaysia has comfirmed - 8 Locations to build the first Nuclear Reactor, but where? Jom, discuss!! PLEASE VOTE AS WELL AT OUR POLL

Hello all!. We are back. This is one of the things that we want to discuss together.

Actually, last week, Malaysian Government has confirmed that they have identified 8 locations that are the most suitable to build the first nuclear reactor in Malaysia, but they do not mentioned specifically which locations that the nuclear reactor will be built. So, this really shows that our government has taken serious steps in making the nuclear energy as one of the new technology that we need in the future.

So, what about, we all try to pick a location, and give the reason why it is suitable? There are so many locations that are suitable but it seems, the exact locations are still secret. So, let's discuss!

Guys, now you can vote at our poll at the side. Please vote! And we can discuss here.

GO NUCLEAR !!

Sad but True

After a long semester since July, we have finally arrived at the end of this semester. Which means, there will be no more lecture on MEHB513 since all Uniten students are having the final examination weeks. So, what actually we have achieved through out this course and what actually we think about this course.

Well, first thing first, this does not mean this blog is going to stop once this semester is finish. To all our readers, we will try to update as many post as can be maybe after we have finish the final exam. This is a part of learning process and to stop right here with this informative knowledge about Nuclear Energy, have given us the oppourtunity to learn and think about other technology like Nuclear Energy.

So, so far, we think this course has given us the knowledge and a lot of essential informations not just about the physics part, which means all the calculation but has given us thought about the environment. How to really help the environment and to sustain all the things that we have right now, especially the energy demand. With this course, we have realized the important of gaining the energy but at the same time, environment improve.

Nuclear Energy definitely a 'Green Technolgy' compare to other energy industries nowadays. Although it is has a lot of benefits compare with the existing energy industries, there are still some disadvantages of this system. It is normal since not all things in this world are perfect. But the imperfection can always be improved.

So, do we need the nuclear energy to be operated in the near future? The answer will always be Yes but are we ready to accept this technology in the near future? For us, the answer still 'Not Yet' but still, it depends on the situation in Malaysia in the next 10 to 20 years. Why we can do it? Because we have a prototype and research and development already about the nuclear energy. Furthermore, with the increase of nuclear engineers nowadays in Malaysia will give a lot of advantages to nuclear energy in Malaysia in the near future.

Energy demand will always increase, as well as the population. So, to really supply sufficient energy to the people, new device or technology is always welcome. Then, nuclear energy will always first come to mind. We hope that to all our readers, please comment and spread this information to any related people that you might know since nuclear energy in the future. We have start to think how actually we can change the misconception about nuclear energy to the people around us who still not aware the advantages of nuclear energy.

Furthermore, we would like to thank to all our lecturers who have taught us and supply the most important information though out the semester. We thank you a lot!. And all the best to all Uniten students in the coming examination.

GO NUCLEAR ENERGY!! =)

More myths on nuclear power

1. It's a nuclear bomb waiting to happen.

People don't realize that in order to make a nuclear bomb, you will need to specifically made it to be a bomb. Nuclear power plant is designed specifically not to be a bomb. People always say what if the nuclear reactor blows up it will become a bomb. Well, even a normal gas power plant  will blow up and becomes a bomb if you want it to. But ironically, no one is scared of a gas power plant blowing up. Nuclear power plant are designed to be safer than any other type of power plant. Even with the worst case scenario for a nuclear power plant it would still not blow up but it will melt down.

2. There's not enough uranium for the next 50-100 years.

With more advance reactor being created and used, the fuel efficiency will increase. It means, it will need less fuel to generate the same electricity. With new modern reactors having up to 99.5% efficiency, surely there will be enough uranium to last thousand of years. If you still not convinced, how about using thorium as nuclear fuel. As thorium is as 4 times more abundant than uranium, there is no problem in finding fuel for the reactor. Mind you, we are not going to use nuclear forever and ever. It's for us to buy enough time to develop new energy technology that are sustainable.

Reactor Safety

We can say that the reactor pose no threat to the environment and the society as long as the reactor power level is being controlled. Also, a reactor is considered safe when the fuel is cooled by some sort of cooling mechanism. Lastly, the level of radioactivity inside the reactor must be contained. During at all times, even during shutdown, the reactor must need to be controlled, cooled and contained.

So what will happen when there is not enough fuel cooling? The major threat to safety is when the fuel overheats. This will lead to fission product gasses being released from the ceramic. When it overheats, the gas pressure inside of the fuel pellets will also increase. As temperature rises near melting point, the sheath will soften and will rupture causing fission products to be released into the coolant.

To solve this problem, the basic rules are:

• The heat that produced by the fuel must be less than the capability of heat removal in the reactor.
• The reactor temperature must always be kept below of the melting point of materials used inside of the reactor.

Containment is important for nuclear reactors because it is the last defense to ensure the safety of the power plant. Containment make sure nothing is being released into the surrounding areas. If reactor control and cooling mechanism failed, public safety will depend on the effectiveness of the containment.

Nuclear Waste is Not Such a Waste. =)

Hello again and welcome to our dearly blog promoting nuclear energy.

First of all, we would like to thank all the readers who have been following our progress through this entire course. Without you all, the information will not be spread out. Hence, we are very grateful that you all have responded at least one of our posts. Thank you. So, from the previous comments that we have read, many of you asked about the nuclear waste and we know, this is one of the most concern matter for any people who wants to really now and try to accept the technology of nuclear energy.

If we can recycle our garbage and turn it into something usable why we shouldn't do the same with nuclear waste. To simply put it, nuclear waste recycling is separating the parts that we want (in this case uranium and plutonium) from nuclear waste or called spent fuel. By recycling, we can extract the uranium and  plutonium that still has a lot of energy that we can harvest from. We you take out this two elements from the waste, the waste itself will be more stable and this mean it will be easier to handle and it can be stored safetly.

As been mentioned before, the product of fission process has produced wastes that we do not needed anymore but the waste is too dangerous because of the radioactivity which all nuclear wastes must be kept safe under proper supervision and we cannot just throw away the wastes anywhere. These wastes must be managed in ways which safeguard human health and minimize their impact on the environment.

But one of the most interesting fact about nuclear energy is that, nuclear energy is the only energy industry which takes full responsibility for all its wastes, and costs this into the product. Which means, other energy industries (you all know what we mean) do not take a really responsibility about their wastes. That is why we can call nuclear energy is the greenest of all because nuclear energy really concern about the wastes compare to any other energy industries existed.

So, there are several general radioactivity wastes from nuclear reaction. It can be divided into three groups, which are:

1. Low-level Waste - Occur because of the nuclear fuel cycle and not dangerous to handle but must be disposed of more carefully than normal garbage.
2. Intermediate-level Waste - contains higher amounts of radioactivity and may require special shielding but It may be solidified in concrete or bitumen for disposal.
3. High-level Waste - It contains the highly-radioactive fission products and some heavy elements with long-lived radioactivity.

But among of all there wastes, the most interested type of waste that most nuclear engineer would like to seriously control is the High-level Waste.

As more and more nuclear plants will be build in the world, the build up of waste from these reactors will also increase in time. You need to remember that average life span of a  nuclear fuel inside a reactor is around 20-30 years. In time you will need to take out the used fuel and put it new one inside the reactor. So if we recycle this nuclear waste, there will be less waste that need to be put away and more fuel will be available to be used in reactors.

"France, in contrast, now reprocesses well over 1000 metric tons of spent fuel every year without incident at the La Hague chemical complex, at the head of Normandy’s wind-blasted Cotentin peninsula. La Hague receives all the spent fuel rods from France’s 59 reactors. The sprawling facility, operated by the state-controlled nuclear giant Areva, has racked up a good, if not unblemished, environmental record. " taken from http://spectrum.ieee.org/energy/nuclear/nuclear-wasteland

 A picture showing the storage tank for nuclear fuel cell

How we promote nuclear energy to Malaysia...

With so many modern applications in the internet nowadays, the information and knowledge can be spreaded faster compare to the old days of technologies. Hence, we as a group would like to present something that might change the mentality of Malaysia people mostly about nuclear energy.

Enjoy this video done by us.....

Nuclear Energy in Malaysia = No Support??

When we talk about nuclear energy, a stereotype person will always think about nuclear bomb, about radioactivity, about chernobyl or any kind of negative effects. We cannot blame them because the knowledge about the effectiveness of a nuclear energy are now well explained which many people have miss the actually functionality of this system. Hence, we think with a proper education system and a way better spread of information, we can teach and educate many people especially in Malaysia about the goods and advantages of having a nuclear power reactor to generate energy for electricity.

Malaysia is considering to build the first ever nuclear reactor on 2021, which means about 11 years from now. It seems Malaysia is serious in making this system works here. Although there are some voices who are very concern and neglect this system totally for Malaysia, we still think it is better for the future. So, how actually we want to educate the people in Malaysia to know the advantages of this nuclear energy system in 11 years time?

Well, with the concern of global warming, all people in Malaysia experience it. We can feel how the wheather changes everytime and how actually the temperature at certain area in Malaysia. The heat is too high to be conformed with! We seems to have drink at least 3 or 4 mineral waters per day just not to get dehydrated. This is because the global warming. This global warming occuring because the CO, CO2 or hydrocarbon gases that being released from many sources that include combustion, like our cars, the factory and now surprisingly, our own power plant which uses the coal as the main burner to generate heat for electricity.

With the no CO or CO2 emission will be emitted through out the heating process, nuclear energy is ideal for the environment. Maybe the effect will not be instantenously but with a smaller reduction percentage, it still can help the environment. Same with the automotive industries which there have develop the hybrid engine which still emiited CO and CO2 to the environment but with the concern from people for environment, the small percentage can still help the environment if all are using the system. And this is also same for nuclear energy.

According to some, even when accounting for the fossil fuel used in mining uranium, processing it, building and decommissioning of the nuclear plant, the picture remains good from this perspective. Less than one hundredth of carbon dioxide gases  is produced by nuclear power plants compared to coal or gas-fired energy plants. This means nuclear energy also emits less greenhouse gas than renewable energy sources such as hydro, wind, solar and biomass. Lower greenhouse gas, the lower the temperature will be.


Furthermore, nuclear energy is a very efficient energy source up to date. Why? Because with a very small amount of fuel (uranium, like have been mentioned before in the other post), the power generation is enormous! Enormous energy production = Efficient! Hence, there are a lot of energy can be produced to generate electricity. Can be reach about almost 1GW of energy, dependent on the system itself. One ton of uranium produces more energy than is produced by several million tons of coal or several million barrels of oil. With the price hike of the oil and coal, nuclear can be said the ideal solution for Malaysia in the future.


"The same la, uranium also very expensive. So, no use of using nuclear.." It is true, uranium is also expensive because the source is not easily found. Furthermore, the demand now a days is high, which means the supplier need to rise up the price also, according to the demand. But if we compare the expenditure of uranium with the energy that nuclear would generated, with the expenditure of coal with the energy produced, nuclear energy will end up to be the most worthwhile energy source because of its high energy generation. 

The only concern for the cost is for the construction of the reactor because it is hard to manufacture. But although it is expensive to manufacture, there is no different from any other power plant to build. But the space or compound require to build the nuclear power plant is quite smaller compare to other power plant like hydro. Smaller compound = smaller destruction  to the environment. Hence, the environment also can be saved slowly by nuclear power plant.

These all information from us are definitely to try to change the misconception of the people around about nuclear, especially in Malaysia because it seems, this nuclear power plant is quite underestimate by the people. Although there are some pros and cons for nuclear energy, with the situation in Malaysia, it seems this is one on the proper way to really contribute to the environment. 11 years is quite a long period but with a proper education and the spread of information, we can change our own stereotype of thinking about the nuclear power plant. One failure does not mean the entire system is a failure. Sustainability is the way of improving things. The same with nuclear energy.

Go Nuclear for Malaysia 2021

What is actually Uranium?

Since there are a lot of talking about the nuclear and right now, as we go further into this kind of topic, so, one will think, what actually Uranium? So, there are some interesting part of Uranium for nuclear reactor that can be discussed with.

Well, uranium is a metal, like any other metal which is the heaviest occuring element on earth and occurs in many isotopes, like 16 isotopes. Before even the 20's era, uranium was not even has a high value in market, which means uranium still not highly demanded by the industries back in the time. Then until the last fifty years it was produced only as a by product and generally, for other essential purposes like nuclear power plant. Uranium was discovered by Martin Heinrich Klaproth in Germany in 1789. Uranium was the first element that was found to be fissile.
 
Like any other internal combustion engine, it uses gasoline or diesel as the sole fuel, which in nuclear power plant, Uranium is the sole fuel of the nuclear reactor, to generate energy which will be transfered to the turbine to generate electricity. About 1 kilogram of uranium-235 theoretically could produce about ~80 TERAjoules of energy, which is equivalent to the energy that could be produced by 3000 tonnes of coal! Since Malaysia is using coal as one of the main materials to generate electricity, imagine how nuclear can contribute a lot of energy enough to supply electricity to us about 50 years, 100 years? =)
    
Furthermore, with the high rate of fission, it can produce a lot of energy which is enough to really generate the electricity. If the fuel of uranium is sized about small pencil can produce the same amount of energy like 3000 tonnes of coal, this definitely means the rate of efficiency is good. But all the good things, no matter how it is good, there is must be some kind on disadvantage about it. Nuclear explosions produce radiation. The nuclear radiation harms the cells of the body which can make people sick or even kill them. Illness can strike people years after their exposure to nuclear radiation.
 
But some people have take this characteristics of uranium as an advantage to create the nuclear bomb. This is why many people are afraid once they hear about nuclear - NUCLEAR BOMB. The main different between nuclear reactor and nuclear bomb is that nuclear reactor is the generate energy and therefore electricity so that people can use it for daily purposes, wheres nuclear bomb is definitely for destruction. People always have any kind of ideas to misuse anything or everything that actually for other purposes. 

This is why we come with this blog to really open many people's eyes so that we see this type of energy source is not the kind that they are thinking about right now, mostly. This is one of the solution to really help the environment. With the global warming is highly occurring now a days, with nuclear, we definitely can contribute in the reduction of global warming. So, come on, we think about it and really push for nuclear in Malaysia. Go nuclear for Malaysia.

Alternative Energy: Toward Nuclear Power Option as Energy Sources for Generating Electricity in Malaysia

Malaysia has experienced strong economic growth in the last decades. Energy has been a key input to the development and growth of the country. Taking into account the growing energy consumption and domestic energy supply constraints, Malaysia has set sustainable development and diversification of energy sources. Malaysia faces complex choices as it looks to expand it energy mix to ensure its energy security. The electricity demand of Malaysia will increase by 4.7% per year over the outlook period, to reach 274 TWh in 2030.

The per capita electricity demand is projected to be double to 7571 kWh/person in 2030.

The electricity generation mixture consists of gas, coal and hydro-power as the major contributor and a few from oil as well as renewable source like biomass, solar and wind. The generation of electricity from fossil fuels is not just facing the depletion and escalation of prices, but also is a major and growing contributor of pollutants such as CO2, NOX, SO2 for global warming. Meanwhile most renewable sources are either not in full scale commercial capacity or had a significant consequence to the environment. Various environmental, cost and fossil fuel depletion issues have lead most nations including Malaysia, to re-look on the possibility of using nuclear as an energy source in the future as nuclear power plants have much longer lifespan and cleaner source of energy, vis-a-via fossil fuel plants.

Article from Berita Harian, May 26,2009, (pg 25)

Nuclear Fuel Conversion

After the uranium deposits taken out from the earth, it will go through a process call conversion. The uranium deposits are not in its pure form but as Uranium Oxide (U₃O₈).  This material is also known as yellow cake because of its bright yellow color. During conversion process, Uranium oxide will be converted into Uranium Hexafluoride (UF₆). Since at high temperature Uranium Hexafluoride will turn into gas substance but will change to solid form when at room temperature. This will make it easier to transport it or to process it. That is why most commercial uranium enrichment facilities use it. Before it is being send to the next process that is Enrichment, it will be turn to gaseous state first. 

Iranian technicians at the Uranium Conversion Facilities in Isfahan.

Mining for Uranium

According to the World Nuclear Association, the largest national share of nuclear reserve was Australia (1,243,000 tones, 23%), followed by Kazakhstan (817,000 t, 15%), Russia (546,000 t, 10%), South Africa (435,000 t, 8%), Canada (423,000 t, 8%), USA (342,000 t, 6%), Brazil (278,000 t, 5%), Namibia (275,000 t, 5%), Niger (274,000 t, 5%), Ukraine (200,000 t, 4%) and Jordan (112,000 t, 2%).

With current technology, there are three main techniques in use for uranium mining. These are open pit mining, underground mining, and in situ leach mining. In open pit mining, the land above the material is blasted and dug away to reveal the ore body. After they have found the fuel deposit, it will be blasted, excavated and removed with dump trucks. Underground mining is carried with access tunnels, and drilling and blasting. In situ leach mining involves drilling boreholes down into an ore body, pumping a leaching fluid into the ore and then pumping the resulting solution to the surface to extract the uranium. The leaching fluid is sometimes a combination of acids or sometimes alkaline solution. The type of the solution used depends on the type of the ore body.  

 Ranger Uranium Mining Plant in Kakadu, Australia

The future of nuclear? :D

taken from greennuclearbutterfly.blogspot.com

Malaysia Energy Option - part 2

Currently in Malaysia there is a lack of available competitive and sustainable alternative energy sources for the long term. At the moment we rely heavily on gas, oil, hydro and coal for our energy. As prices for gas and oil increases, so does the operating cost that will be burdened by the utilities companies. The same goes for coal, as our country import over 90% of its coal from other country such as Australia and Indonesia. Yet, coal seems unable to meet with the nation's ever increasing demand for electricity. Because of this, we need to enhance our national energy security due to depleting indigenous resources. We also need to reduce our greenhouse gas emissions.

That's where nuclear energy comes in. Among the key point of nuclear power is the nuclear fuel is energy intensive. Also nuclear power refueling cycle is between 12 to 24 months. Which means that the nuclear plants can be operated without interruption for a few years. Also not to mention that nuclear power plant has zero carbon emission. This will go a long way in solving the world's CO2 emission problem.

It can be observed that countries with higher Gross Domestic Product (GDP) and energy consumption per capita than Malaysia have gone for nuclear power. But also some countries with lower GDP and energy consumption per capita than our country are thinking of nuclear power.

Malaysia Energy Option - Part 1

During the past 50 years, global coal usage has doubled, while oil demands has risen sevenfold and natural gas usage more than tenfold. Fossil fuels such as coal, natural gas, petroleum, oil shale and tar sands won’t last forever and eventually they will be exhausted.

“Malaysia's leader warned of a global crisis over the tussle for energy resources amid declining supply, and urged major oil producers and consumer nations to jointly develop new resources. The growing demand for depleting oil and gas resources is likely to trigger more intense competition to gain access and control over these resources” (“PressTV website”, June 2006).

Malaysia is an oil exporter, but if we do not find new oil reserves, then in the near future we will become a net importer, this means we cannot continue to lean on the oil sector. Also, the price for fossil fuels has gone up drastically in the recent years. We are too dependent on fossil fuels which mostly are imported for our energy supply.

According to The Star on the date 20^th September, 2008, Malaysia will turn to nuclear energy to generate electricity by 2023 as supplies of fossil fuel eventually run out. Energy, Water and Communications Minister Shaziman Mansor said,” the use of nuclear energy was also an alternative to counter high global oil prices. The increase in coal prices had been exceptional and we need to act now”.

“The government would look at alternative energy sources, including nuclear power, to help the nation reduce its reliance on oil, which has hit nearly US$140 a barrel on global markets. The government hiked fuel prices this month by 41 percent, saying the deeply unpopular move was needed as subsidies would have ballooned to US$17 billion this year” (“The China Post Website”, 2008, paragraph 2).

The Malaysia’s national energy situation is that the country is lacking of available competitive, sustainable alternative commercial energy sources for the long-term, especially beyond 2020. Thus there is a need to enhance national energy security due to depleting local resources.

Nuclear Poison

A nuclear poison is a substance with a large neutron absorption cross-section. Simply put, it can absorb neutron very effectively.

Where do these poisons come from? For starters, in the nuclear reactor, there will be material that is produce by the fission reaction that can absorb a lot of neutrons. Because we need neutrons to keep the reactor running, having less neutrons will result in less power being generated. In fact, if the poison level is unchecked, it may cause the nuclear chain reaction in the reactor to stop.

The radioactive materials in the reactor will decay. From time to time, there will be materials in the reactor that its decay process will result in a new substance that have a high neutron absorption cross section. This too will lead to an increase in the amount of nuclear poison.

Let's say that u have a jug of water. Then, a sponge is put inside the jug. After a while, you will noticed that the level of water inside the jug has decreased. Imagine that the water is the neutron and the sponge is the poison. Neutron level will be reduced by the existence of the poisons.  

But sometimes, you will need to keep some amount of poison in the reactor. Why you ask? It is because the poisons can be used to regulate the reactivity of the reactor. For example, you want to run the reactor with a 200 grams of U-235. Since the radioactive material will decay, the amount of fuel will decrease over time. In order to solve the problem, you will need to put more than 200 grams in the reactor. The more fuel you use, the reaction rate will be higher. So to effectively control the neutron level, poison is put inside the reactor.

Control Rods for Nuclear Reactor, what is that?

Hello guys and girls...

Today was quite a lecture given by the lecturers about the types of control rods inside the nuclear reactor. It has given us an idea in about to think what actually the control rods and what does it do inside the nuclear reactor? Hence, some research was done to actually get the information that will beneficial to all of us, especially who wants to know about the nuclear power system.

Control rods - It is a rod made of chemical elements capable of absorbing many neutrons without fissioning themselves (Wikipedia). In other words, the rods is a device that have the ability to adsorb a lot of neutrons inside the nuclear reactor. This is essential to the nuclear reactor because these rods will control the rate of fisson of uranium and plutonium inside the nuclear reactor. So, what is the reason for why the rods have that such kind of ability to absord neutrons? As an engineer, with the sense of logic, the answer to that question must be the material of rods itself. Which means, the materials used are the one that given the rods the ability to adsorb such neutrons. The commonly used materials which satisfy these criteria include cadmium, boron, iridium, silver and hafnium. These types of materials are the used materials that have a higher percentage in absorption ability of the neutrons.

There are also several types of control rods for the nuclear reactor. As can be found generally, there are three common control rods for a nuclear reactor now a days. Which are:

1. Shim rods - used  for  coarse  control  and/or  to  remove  reactivity  in  relatively  large amounts.
2. Regulating rods   - used for fine adjustments and to maintain desired power or temperature.
3. Safety rods -provide a means for very fast shutdown in the event of an unsafe condition.




So, it can be said that the rods are the device that has the ability to control the rate of the fission inside the nuclear reactor. This is one of the safety measure for the nuclear reactor so that any explosion or over fission inside the nuclear reactor will not occur. Although the more fission occur will produce more energy, but in some measurement, over energy can result in some uncontrollable or out of control. The higher rate of fission also can cause a higher levels of radiation and nuclear waste will occur which are harm to the people. Sometimes, more is less. So, the best result will always be the optimum of all.

So far as can be concerned, this nuclear system actually has what it takes to be the next renewable energy that can replace the existing type source of energy. There are still a lot research and development to do in Malaysia, since we are still a developing country but in the near future, this technology will be ideal to be constructed and implemented in Malaysia. This blog will be updated with more information and knowledge that can be share through out the world. Sharing is caring.

Nuclear For Malaysia.

Benefits of Nuclear Power

• It's a clean way to produce energy as it does not result in the emission of any of the poisonous gases like carbon dioxide, sulfur dioxide or nitrogen dioxide.

• It has been proved that if a typical family of four uses nuclear power for all its needs then the waste produced over a period of a lifetime would be as small as a golf ball.

• Nuclear power is an extremely reliable power source because the reactor have a life cycle of 40 years and be easily extended to 40 years.

• The source of nuclear power is uranium and this is available in abundance in the crust of the Earth with major deposits being uncovered in Canada and Australia. Therefore since the source of nuclear power is readily available now and also for centuries to come, this form of power is virtually inexhaustible.

• The biggest fear associated with nuclear power is the fear of radiation and this can only be overcome by educating the people about the method of radiation and its behavior. People would be surprised to know that radiation has been a part of our environment ever since its existence and that radiation in moderate amounts can even be advantageous to our health. Therefore, radiation need not be feared from but can be channeled appropriately to serve mankind in a positive way

• Nuclear power is good and scientific as well as environment friendly because of which it is being supported by many ecological organizations and environmentalists who were previously biased against it.

 picture taken from www.mattglover.com

reference: www.alternate-energy-sources.com/advantages-of-nuclear-energy
reference: www.benefitsofnuclearpower.com

Nuclear power plant myths

1) Uranium is running out

There is 600 times more uranium in the ground than gold and there is as much uranium as tin. There has been no major new uranium exploration for 20 years, but at current consumption levels, known uranium reserves are predicted to last for 85 years. Modern reactors can use thorium as a fuel and convert it into uranium  and there is three times more thorium in the ground than uranium.

Uranium is the only fuel which, when burnt, generates more fuel. In short, there is more than enough uranium, thorium and plutonium to supply the entire world’s electricity for several hundred years.

2) Nuclear is not a low-carbon option

During its whole life cycle, nuclear power releases three to six grams of carbon per kiloWatthour (GC kWh) of electricity produced, compared with three to 10 GC/kWh for wind turbines, 105 GC/kWh for natural gas and 228 GC/kWh for lignite (‘dirty’ coal).

3) Nuclear power is expensive

With all power generation technology, the cost of electricity depends upon the investment in construction , fuel, management and operation. Like wind, solar and hydroelectric dams, the principal costs of nuclear lie in construction. Acquisition of uranium accounts for only about 10 per cent of the price of total costs, so nuclear power is not as vulnerable to fluctuations in the price of fuel as gas and oil generation.

4) Reactors produce too much waste

Production of all the electricity consumed in a four-bedroom house for 70 years leaves about one teacup of high-level waste, and new nuclear build will not make any significant contribution to existing radioactive waste levels for 20-40 years.

5) Building reactors takes too long

The best construction schedules are achieved by the Canadian company AECL, which has built six new reactors since 1991, from the pouring of concrete to criticality (when the reactors come on-line), the longest build took six-and-a-half years and the shortest just over four years.

6) Leukemia rates are higher near reactors

Childhood leukemia rates are no higher near nuclear power plants than they are near organic farms. ‘Leukemia clusters’ are geographic areas where the rates of childhood leukemia appear to be higher than normal, but the definition is controversial because it ignores the fact that leukemia is actually several very different diseases with different causes. Men who work on nuclear submarines or in nuclear plants are no more likely to father children with leukaemia than workers in any other industry.

7) Reactors lead to weapons proliferation

More nuclear plants would actually reduce weapons proliferation. Atomic warheads make excellent reactor fuel; decommissioned warheads (containing greatly enriched uranium or plutonium) currently provide about 15 per cent of world nuclear fuel. Increased demand for reactor fuel would divert such warheads away from potential terrorists

8) Reactors are a terrorist target

Terrorists have already demonstrated that they prefer large, high visibility, soft targets with maximum human casualties rather than well-guarded, isolated, low-population targets. Any new generation of nuclear reactors  will be designed with even greater protection against attack than existing plants, and with ‘passive’ safety measures that work without human intervention or computer control.


reference: www.spiked-online.com/index.php?/site/article/4259/
reference: www.wna.org
reference: www.washingtonpost.com/wp-dyn/content/article/2009/03/20/AR2009032001781.html
reference: www.cleanenergyinsight.org/interesting/wednesday-fact-series-npps-dont-cause-cancer/

Nuclear safety systems

There are 3 primary objectives of Nuclear Safety Systems which are:

• to shutdown the reactor
• maintain it in a shutdown condition
• prevent the release of radioactive material during events and accidents

One of the safety system implemented is the Reactor Protection System. It is composed of systems which are designed to immediately terminate the nuclear reaction. While the reactor is operating, the nuclear reaction continues to produce heat and radiation. By breaking the chain reaction the source of heat can be eliminated and other systems can then be used to continue to cool down the core. All plants must have some kind of these systems.

Another important system is the Emergency Core Cooling System (ECCS). The system comprises a series of systems which are designed to safely shut down a nuclear reactor during accident conditions. These systems allow the plant to respond to a variety of accident conditions and at the same time creates redundancy so that the plant can still be shutdown even if one or more of the systems fails to function.

Under normal conditions, nuclear power plants receive power from off-site. However, during an accident a plant may lose access to this power supply and thus may be required to generate its own power to supply its emergency systems. These electrical systems usually consist of diesel generators and batteries.

There's a containment systems are designed to prevent the release of radioactive material into the environment. It includes fuel cladding, reactor vessel and primary and secondary containment.

In case of a radioactive release, most plants have a system designed to remove radiation from the air to reduce the effects of the radiation release on the employees and public. This system usually consists of containment ventilation and control room ventilation.

reference: www.ask.com/wiki/Emergency_Core_Cooling_System

Reactivity Coeffcients and the Chernobyl Incident

The reactor involved in the Chernobyl nuclear accident was a 3,200-MWt RBMK (High Power Channel-type Reactor), a boiling-water pressure-tube, graphite moderated power reactor that was developed and operated in the former Soviet Union.

 

The Chernobyl Nuclear Power Plant.

Because of the pressure-tube design using water as coolant within channels in the graphite moderator, RBMK reactors have a significant positive void coefficient of reactivity in which a reduction in the coolant density results in an increase in the system reactivity due to a reduction in neutron absorption by the coolant. This reactor also has a positive moderator coefficient of reactivity in which the reactivity increases as the temperature of the moderator increases. Both of these operating characteristics are compensated by the negative temperature coefficient of the fuel which loses reactivity as the fuel temperature increases.

 Schematic diagram of an RBMK reactor.

At 00:28 on the day of the accident, the monitoring systems were adjusted to the lower power levels, but the operators failed to reprogram the computer to maintain power in the 700 to 1000 MWt range. The power fell to 30 MWt. The majority of the control rods were withdrawn to counteract the negative reactivity effect of xenon (fission product) poison which built up during the delay in power reduction. The power climbed and stabilized briefly at 200 MWt. At 01:03 All eight pumps were activated to ensure adequate cooling after the test.

The control room inside reactor 4 at Chernobyl

This violated two rules, one on high flow rate, the other protecting against pump cavitation. The resulting high flow rate increased heat transfer and thereby maximized coolant (neutron) absorption to require still more (prohibited) control rod withdrawal. It also maximized the reactivity increment available from the change in neutron absorption associated with coolant voiding. The combination of low power and high flos produced instability and required many manual adjustments. The operators turned off other emergency shutdown signals.

Engineers test a reactor's control panel at the Chernobyl nuclear power plant control room in Chernobyl

At 01:22 The computer indicated excess reactivity. Under pressure to complete the test, the operators reserved the possibility of rerunning the test by blocking the last remaining trip signal just before it would have shut down the reactor. "01:23 The test began. As power started to rise, coolant voiding increased and, through the positive reactivity feedback mechanism, led to accelerated power increase. Recognizing the potential consequences, the operators began insertion of all control rods.

 

Inside Chernobyl number 3 reactor unit

The power surged to 100 times the reactor's normal capacity in the next four seconds. A second pulse may have reached nearly 500 times full power and caused the fuel to disintegrate, breach the cladding and enter the water coolant. A steam explosion was caused by contact of the fragmented fuel with the water-steam coolant mixture.

The resulting force lifted the massive top shield, penetrated the concrete walls of the reactor building, and dispersed burning graphite and fuel. Oxidation of zirconium and graphite produced combustible hydrogen and carbon-monoxide gases that may have contributed to additional explosions. The initial excursion by itself was well beyond the containment design basis. It blew off the building roof and sent a plume of radioactive gases and particulates high into the atmosphere.

Aerial view of the damaged core. Roof of the turbine hall is damaged 

Short documentary on the Chernobyl Accident

reference: http://en.wikipedia.org/wiki/RBMK
reference: https://hps.org/publicinformation/ate/q1743.html
reference: http://en.wikipedia.org/wiki/Chernobyl_disaster 

Reactivity

Reactivity is the measure of the departure of a reactor from criticality. In the nuclear reactor, the control rods are being used to control reactivity.

For example, we take Uranium-235 that is being used as fuel in a nuclear reactor. When the nucleus of U-235 are struck by a slow-moving neutron, they will under go fission reaction. As by products of the reactions, it will release fragments, radiation, and neutrons. If these neutrons are slowed down  and hit another U-235 nucleus, that nucleus will also fission and  continues the chain reaction.

 Figure showing the fission of U-253 nucleus

For the chain reaction to be self-sustaining, each generation of fission events has to produce enough neutrons so that there are enough are left to cause just as many fission events in the next generation.

Positive reactivity causes power to rise exponentially proportional to the reactivity. Negative reactivity causes power to decrease. To change power in a planned manner, reactivity is adjusted by moving the control rods, either manually or by means of automatic controls. Partially removing a control rod is expected to increase the reactivity, causing the power to rise to a new level.

 

Figure above shows the effect of a relatively large initial reactivity leading to a rapid rise to a blowup.

The effective neutron multiplication factor, k, is the average number of neutrons from one fission that cause another fission. The value of k determines how a nuclear chain reaction proceeds: 

if k < 1 (subcriticality): The system cannot sustain a chain reaction, and any beginning of a chain reaction dies out over time.  

if k = 1 (criticality): Every fission causes an average of one more fission, leading to a fission (and power) level that is constant. Nuclear power plants operate with k = 1 unless the power level is being increased or decreased.

if k > 1 (supercriticality): The result is that the number of fission reactions increases exponentially.  

reference: www.wordiq.com/definition/Nuclear_chain_reaction 
reference: www.sizes.com/properties/reactivity