The Nuclear Fuel Waste Engineering Essay

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Nuclear waste gives a lot of problems. The big question is what to do with it or what is the best way to dispose of it. For the present nuclear waste is being stored. Today there are many ways of treating nuclear waste and storing it. Storing is only a temporary solution. A permanent one needs to be found. The waste, which can be toxic and dangerous, can last for many years (Oracle Thinkquest 1998; World Nuclear Association 2007).

What is Nuclear Waste?

Nuclear waste is leftovers and waste after production in nuclear reactors. This can be from power plants, research or nuclear bomb making. The waste can be divided in different categories. These are low, medium and high-level waste (World Nuclear Association 2007).The level depends on the radioactivity coming from the waste products (Assinimov 2010).

Nuclear Fuel waste

Waste can come from uranium used in reactors. This is extremely radioactive waste. Much waste remains in the fuel rods used in reactors. A lot of it is produced in the US and in Canada and in other developed countries in Europe. Japan also has nuclear plants. One option for waste management is to store it for a long time under water in cooling ponds at the power reactor site. Concrete and water also offer some protection (World Nuclear Association, 2007).

Radioactivity:

Radioactivity is forthcoming from the breakdown of elements called isotopes. Many isotopes are radioactive while others are not. According to the World Nuclear Association, radiation can be classified into three types: alpha, beta and gamma. Another type, neutron radiation is found inside a nuclear reactor. The different types of radiation need different forms of protection. Alpha radiation cannot enter the skin and can be blocked by paper; however it is dangerous in lungs. Beta radiation can enter the body but protection by means of foil is possible. Gamma radiation is dangerous and can go through the body. This type can be blocked by layers of lead or concrete. A meter or more water will also be effective. All of these kinds of radiation can be found in nuclear waste (World Nuclear Association 2007).

Radioactive waste

Radioactive waste can be classified in different types: low-level, intermediate and high-level waste.

Low-level waste: this can be found in hospitals, industry and laboratories, and as part of nuclear fuel. This would be made up of paper, cloth, clothing, filters and tools used. These would have small amounts of short-lifespan radioactivity. Although not dangerous to handle, it must nevertheless be disposed of in a better manner than normal garbage. The usual treatment is burying it in landfill sites. To cut down on its volume, it is compacted or burned in a closed container before disposal. It is estimated to make up about 90% of worldwide volume but only accounts for about 1% of all radioactive waste (World Nuclear Organization 2007).

Intermediate-Level waste: this contains a higher level of radioactive material. As such it will need more careful handling. This is made up of chemical leftovers, resins as well as nuclear reactor parts. Some parts come from plants no longer being used. This makes up an estimated 7% of worldwide volume with about 4% of radioactivity of nuclear waste. One manner of disposal is to enclose it in concrete for disposal. The short-lived waste from reactors is buried. Waste with a longer life-span coming from nuclear fuel is buried deeply underground (World Nuclear Organization 2007).

High Level waste: this is mainly used fuel. It is about 3% of world volume but is about 95% of radioactive waste. It is the long-life waste. This type of waste gives off a lot of heat and needs cooling. When handling this waste protection is necessary. It also needs special forms of transportation. The waste from reprocessed fuel is mixed with borosilicate (Pyrex) glass and then placed inside stainless steel containers. These containers are buried deep underground (World Nuclear Organization 2007).

Radioactive waste usually comes from commercial nuclear power plants. The fuel used in these plants is made of pellets of enriched uranium. These are sealed in fuel rods. The rods are bundled together into fuel assembly. The fuel assembly of rods powers the nuclear reactor. These are being used until the efficiency of electricity production is done. The 'used' or 'spent' fuel rods become nuclear waste. These rods are highly radioactive. The spent or used fuel rods are radioactive and hot. These are placed in pools for 'spent fuel' rods to cool down. In this state, some of the radioactive waste can decay. Once pools are full, then they need to look for new storage space (Thinkquest 1998). Another method of storage is in the form of concrete holders. The waste is enclosed in these concrete containers and stored close to the reactor site.

An important factor in waste management is the time involved in which waste remains dangerous. This is dependent on the radioactive isotopes in the waste. The life-span is measured in half lives. The half life is the time taken for a radioactive isotope to lose half of its radioactivity. After a time lapse of four half lives, the level of radioactivity is 1/16th of the original. After eight half lives it are about 1/256th (World Nuclear Association 2007). These half lives can range from minutes to hours and from days to years. The radioactivity decreases over a period of time and can decay and become less toxic and radioactive.

There are three means of nuclear waste management:

Concentrate and contain it

Dilute and discard

Delay and decay it.

The first two methods are easy and refer to concentrating and isolating it and the next one is to dilute it to harmless levels and throw it away in the environment. Delay and decay is another type where storage is involved over a period of time and then wait for it to decay.

However there are still dangers involved even in old dumps. According to the Nuclear Information Resource Service (NIRS n.d.) exposure to nuclear waste from a 10 year old unshielded dump can expose a person to radiation which can lead to cancer or genetic damage.

Wastes from the "back end" of the fuel cycle 

This type of waste comes from uranium used in the reactors which generate energy. It occurs when the uranium-235 atom is split and forms fission products. These are highly radioactive. It forms the main part of nuclear waste in the fuel rods. It is estimated that about 25 tonnes of waste fuel comes from a 1000MWe nuclear reactor plant. This waste can be treated as waste or it can be reprocessed. Despite it being used as waste or reprocessed, the used fuel is stored under water in cooling dams at the reactor site. The concrete dams and water provide radiation protection. The cool water removes the heat during this decaying stage (World Nuclear Association 2007; Thinkquest 1998).

Nuclear waste sites/ disposal

Nuclear waste disposal is problematic. This is usually so after the nuclear power or product was produced. The waste from a power plant or the military can be dangerous. Because it is no longer useful the headache is on governments. The environmental concern groups are worried about pollution of water and the earth. They put pressure on companies and governments to dispose of the waste in a safe manner. If the waste is not handled properly, then it can be dangerous to human health, animal and plant life. The nuclear waste cannot and must not be buried or washed away in water, such as in rivers or oceans (Annisimov, 2010; Thinkquest 1998)

In the delay and decay treatment of nuclear waste, high-level waste is delayed and kept for 40-50 years. This gives time for the radioactivity to decay and become less harmful. It is then easier to handle and treat. Containers with waste are stored underwater in water ponds or dams. Some of it is stored in dry concrete bunkers for this period of time. Used waste or that which is not re-processed is placed in isolation from the environment. One good method is to bury it as deep as 500meters in stable ground.

It is estimated that after about 1000 years most of the radioactivity will have decayed. Radioactivity remaining in it would be about the same as natural uranium ore from which nuclear fuel is made.

Waste treatment in USA and Europe

In the US high-level waste is stored on site at reactor plants. Most of these will be placed in special containers and stored underground in the Yucca Mountains, Nevada. The funding for it came from the money paid by electricity consumers. In New Mexico, a special location has been built for long-life nuclear waste coming from military products (Long 2002).

In Europe used fuel is also stored on site at reactor sites. It will later be disposed of. Much of the European waste is sent for reprocessing. Special reprocessing plants are in the UK and in France. Uranium and plutonium recovered from this process go back to the countries of origin. The nuclear waste are processed and then sealed in stainless steel containers. These are either stored or returned. After many years they will be disposed of.

In Sweden the process is different. It has its own used storage facility for used fuel. Here it is containerized for disposal at a later stage. Finland is also making its own facility for storing. The money for these European reprocessing and storage comes from a levy paid by electricity users (World Nuclear Association 2007).

REPROCESSING of Nuclear Waste

Reprocessed used fuel results in separated parts of uranium, plutonium and high-level waste. It is estimated that about 97% of used fuel can be recycled. The 3% remaining is classed as high-level waste. The recycled part contains uranium depleted to less than 1% U-235, and some plutonium.

A regular 1000 MWE nuclear reactor can deliver about 230 kilograms of plutonium after reprocessing of waste. This reprocessed product can be mixed with fresh oxide (MOX) fuel. Europe has about 25 years of experience of this type or reprocessing, with the main plant in France, since 1995. Japan has a plant that will start in 2012. More than 35 reactors in Europe are allowed to use MOX fuel (World Nuclear Association 2007).

The high-level waste which is about 3% of a reactor's used fuel comes to about 700kg per year. This needs to be kept away from the environment for many years. The reprocessing plants in France and the UK handle about 5000 tonnes of spent fuel. This is about a third of the world's yearly output. Over the last 40 years about 90,000tonnes of used fuel has been processed (World Nuclear Association 2007).

 

Treating high-level waste 

One way of treating high-level waste is to solidify it. This has been done in many countries for more than 50 years. High-level liquid wastes are evaporated and turned into solids. This is then mixed with glass-forming materials and melted. Then it is poured into stainless steel containers which are closed by welding. A 1000 MWe reactor plant operating for 1 year could fill twelve containers of about 1.3m in height and 0.4m wide. This will hold about 400kg of glass mixture. These vitrification (glass-mix) plants in Europe produce approximately 1000 tonnes of vitrified (glass) waste and would fill 2,500 containers. These plants have been doing so for more than 20 years (World Nuclear Organization 2007).

Protection by means of layers: 

The environment must be protected from nuclear waste radiation. To do so, barriers need to be in place. Layers of protection come in different forms. One form is the borosilicate glass. Another type is Synroc where the waste will be left as uranium oxide fuel pellets. Corrosion-resistant stainless steel containers are the next level of protection. Special containers are surrounded by bentonite clay to prevent groundwater movement in the event of the storage facility being wet. Deep underground burial sites in stable rocky soil are best. If all of these layers of protection are not in place then humans and the environment will be threatened (World Nuclear Organization 2007).

Nuclear waste transportation

The transportation of nuclear waste needs special rules and regulations. Internationally laws and codes as well as regulations have been drawn up by the World Nuclear Transport Institute (WNTI 2008) to ensure the safety of the environment and people.

The International Atomic Energy Agency (IAEA) states that about 10 million of radioactive materials are shipped or moved yearly. This can be a single package or more which will be transported from one place to another. The IAEA published the first rules and regulations for this transportation in 1961. These rules have been modified as time went by to fit in with modern day life. More than 60 member states obey these regulations. The United Nations, International Aviation (Air transport) and International Maritime (shipping) all adhere to the IAEA Regulations. This means that the regulations and rules apply to the transportation of radioactive materials anywhere in the world (WNTI 2008).

Most of the nuclear waste is transported in special containers. The special containers look like large concrete dumbbells and the waste is in the centre. The end sections are called "impact limiters" to protect the waste being carried in the event of an accident (NIRS n.d.)

The IAEA Regulations are set out to stipulate how the radioactive material should be packed and transported. The main idea is to prevent accidental spillage or contamination .The main idea is to protect the environment, people and their property. Radiation to anyone or anything must be non-existent when transporting nuclear waste. Waste must be classified and labeled according to its origin as such and the means of transportation chosen accordingly. Safety must be maintained at all times (WNTI 2008).

Labels, and markings must be clear. Descriptions must also be easy to read .Instructions in terms of any mishap or accident must be clearly displayed so that people know what to do in case of an accident. When the type of nuclear waste is known during an accident, then the correct measures or treatment can be applied to clear up the contamination.

Because the transportation of nuclear waste and materials are strictly governed, no serious mishap or accident happened. Nuclear materials have been transported for many years according to the rules and regulations laid down by the World Nuclear Transport Institute (WTNI) as well as the International Atomic Energy Agency (IAEA). In over a period of 45 years no incident or release of radioactive materials happened. This shows how strict the rules are and how well the people involved with transportation work (WNTI 2008).

In early November 2010, a special train with nuclear waste from France went to Germany for the storage of the waste, in terms of an agreement between France and Germany. "The security measures, under international regulations, involved sealing the solid nuclear waste in glass that is in turn encased in 40-centimeter (16-inch) thick steel containers… the train cars "rolling fortresses" - each benefiting from 100 tons of protective material" (Khaleej Times 2010).

Nuclear countries and usage of nuclear power/ products

According to the World Nuclear Organization (2010), there are about 45 countries who are considering the usage and production of nuclear power. The majority of these countries wish to do so to replace electricity power generators driven by old, oil or coal power plants. Other nations want to make nuclear weapons. Both of these plans are reasons for worry. Besides the problem and worry of weapon production, the nuclear waste issue remains a big one. Both types of production lead to the creation of nuclear waste.

Nuclear power and the UAE

The UAE is set to be the first Arab country to operate a nuclear power plant. It has given the contract to a South Korean company to build 4 nuclear-power reactors. The UAE will use these nuclear power plants for non-military use. It will generate power to become less dependent on electric power generated by old oil-burning processes (ISS 2010). It would be interesting to follow the path of nuclear waste treatment here in the future once these plants are operational. It can be assumed that the UAE will work within the known framework of nuclear waste management and treatment as set out by international bodies (World Nuclear Organization 2010).

Nuclear waste in the Middle East:

In Jordan the first storage area for radioactive waste has been opened. This facility has been created with money from the US Department of Energy and the Jordan Atomic Energy Commission. The storage space is for the safe and secure storage of low and medium-level radioactive waste coming from hospitals, scientific research institutions and other industries. There the radioactive waste will be stored, safeguarded and catalogued (AMEinfo 2010).

Conclusion:

Nuclear waste is produced by the many nuclear reactor and power plants around the world. Nuclear waste is also coming from hospitals, universities and research centers. The nuclear power plants and reactors have been established to provide clean electricity and power as opposed to the old oil-burning power stations. Although these plants cause less pollution, they however pose other risks through the nuclear waste they produce. This waste can be harmful to humans, animals and the natural environment if it is not treated and disposed of in the right way. It is for this reason that there are many methods of treatment applied by the different countries who use nuclear power. One means is to re-process waste materials. The waste that cannot be used is turned into manageable waste and then sealed and stored. Storage can be at the nuclear plant site in water and concrete ponds or in special underground storage or burial facilities. All the while, care is taken not to harm humans and the environment. The transportation of nuclear material and waste is governed by strict rules and regulations. These rules and regulations are drawn up by an international governing body and all countries with nuclear plants are expected to treat waste according to rules and regulations laid down.Until now mishaps with nuclear waste management are rare and it is hoped that this care will be carried on as more and more countries choose to use nuclear energy producing plants.

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