Waste of Nuclear Energy: Spent Fuel
Currently, the world is moving to what can be termed as a ‘closed fuel cycle’. The reason for this lies in the manner, in which recycling of the spent nuclear fuel takes place. Today, most developed countries in the world, such as the United Kingdom, India, Russia and China, reprocess the spent nuclear fuel. Such approach to the issue has proved to be major means, by which countries can substantially reduce or even eliminate the wastage of nuclear energy. Additionally, reprocessing of the spent fuel is an essential step towards ensuring that countries have an energy security. This also reduces both the radiotoxicity and the amount of high level nuclear waste.
Therefore, this paper focuses on the wastage of nuclear energy and more specifically on the spent fuel. In this regard, the paper will consider the spent fuel as a source of energy, evaluate the current state of nuclear technology and reactors, while focusing on the main advantages, disadvantages and limitations of this source of energy.
In addition, the paper will address the issue of how the spent fuel can be used effectively. The potential and future implementation of this source will then be discussed in details.
The paper also analyzes the APR 1400 plant, which is currently under construction in the United Arab Emirates (UAE), together with the role that this plant is playing with regard to nuclear waste reduction measures.
The paper will also address the advantages emanating from the spent fuel, whereas they shape the international research and can influence decisions of different countries regarding the establishment of both regional and domestic nuclear energy repositories.
The term “nuclear waste” describes the end material that results from the process of nuclear fuel being used in respective power reactors. It looks similar to the initial fuel that has just been loaded in the reactor. However, the components are usually not the same. For instance, before being used to produce power in reactors, the fuel is mostly made of uranium, steel and oxygen. After being used in the reactors, numerous atoms of uranium are split into several isotopes that comprise of almost all the elements that can be found in the periodic table (Bunn et al., 2005). This end product, which many people refer to as the waste, is a highly radioactive element. It remains in that form for thousands of years. This waste is what is usually referred to as the ‘spent fuel’. This property of being able to remain in the same form for many years qualifies the material as dangerous and extremely toxic (Von Hippel, 2001). If a person stands within few meters of the material when the last is unshielded, this person will receive a highly lethal radioactive dose just within few seconds and will die within few days due to the acute radiation sickness. This is what makes the spent fuel a critical issue in the modern world.
In terms of a normal practice, the spent fuel is usually shielded. As a rule, it is being kept under the water, whereas it is an excellent shield. The spent fuel is kept there for several years until the radioactive materials decay, hence making the overall levels of radiation fall. This allows for further shielding of the spent fuel by specifically designed tanks. However, the topic of how the spent fuel is ultimately disposed elicits a lot of views. In the first place, there are some arguments which are against the use of nuclear reactors (Todd & Rockville, 2008). However, the most viable options regarding the disposal of the spent fuel include recycling (reprocessing) and deep geologic storage. Despite the form of storage, the process of storing the spent fuel is not the most viable idea. This owes to the fact that the fuel can still contain highly valuable resources which can be harnessed and used in the further process of energy production. Therefore, recycling becomes the most convenient solution, with the help of which the waste of nuclear energy can be prevented. The spent nuclear energy still contains a lot of reactive isotopes which can be split further in the process of nuclear fission so as to produce a reliable energy (Von Hippel, 2001). Additionally, recycling this form of energy highly critical in ensuring that the potential dangers of radioactive elements are eliminated significantly.
Meaning Subset of the Source
The spent nuclear fuel, which is also referred to as the used nuclear fuel, implies that it has been irradiated in nuclear power plants. In an ordinary thermal reactor, the spent fuel is no longer useful for sustaining the nuclear reactions. Depending on the exact point of the spent fuel in the nuclear fuel cycle, it may contain different numbers of radioactive isotopes. Typically, nuclear reactors are usually loaded with the uranium and oxide fuel (Todd & Rockville, 2008). In this regard, there exists intense temperature gradients that cause fission products to migrate. During this process, zirconium tends to move towards the center of the pellet of the fuel. In its center, the temperature is the highest. On the other hand, the lower-boiling products of the fission process move to the extreme edge of the fuel pellet. Thus, it is most likely to contain a large number of small pores which are formed during the use of the respective fuel.
Neutrons are then introduced in the system, where many of them are later absorbed by the uranium atoms contained in the fuel. This causes the atoms to become highly unstable; thus, they split in the process (Paiva & Malik, 2004). This fission results into the smaller atoms which are referred to as the fission products. In some instances, the uranium atoms may absorb the neutrons; as a result, the process of fission may not occur. If it fails to happen, the atoms are transformed to a heavier isotope of uranium such as U-239. The heavier nuclide may then absorb another neutron, which becomes even a heavier element known as transuranic (Kolarik & Renard, 2003). With regard to nuclear reactors, nuclear waste is the collection of nuclides, which are left over after nuclear reactors have extracted some energy needed in the nuclear fuel. Many of the isotopes, which remain after the fuel has been used, are highly radioactive. Therefore, it may take substantially long period of time for the radiation to decay to stable levels Due to its radioactivity, the spent nuclear fuel continues to emit a lot of heat, even long after it has been removed from the reactor. Some of the radioactive isotopes found in the spent fuel are in a gaseous state, and as a result, they have to be contained carefully to ensure that they do not escape to the environment. If they escape, they will cause a crucial radiation damage to living creatures (Paiva & Malik, 2004). Apart from the spent fuel, other forms of nuclear waste exist. All these components have varying applications.
After a nuclear reaction has been stopped as a result of shutting down of a nuclear reactor, the chain of nuclear fission is ceased. Thus, a significant amount of heat is produced due to the beta decay of the fission products. Just after the nuclear reactor has been shut down, the produced decay heat will be approximately 7% of the total power of the reactor, if the latter has a steady and long power history (Kolarik & Renard, 2003). However, after an hour of shutting down, the decay power can amount to about 1.5% of the total core power. The decay heat then continues to decrease with time. The spent fuel removed from the nuclear reactor is stored in a specific place in order to allow it to cool down. A passive cooling may not be a preferable option at this point as it may require many years to reduce the radiation to the required levels. When designing a complete waste management plan for the spent nuclear fuel, the long-term radioactive waste that utilizes the back end of the fuel cycle is relevant to a considerable degree. Due to the long half-lives of the radioactive elements present in the spent nuclear fuel, the actinides in the spent fuel have a highly significant influence.
The process of nuclear reprocessing and recycling can be substantially useful in separating the spent fuel into some various combinations of reprocessed plutonium, minor actinides, uranium, remnants of steel or zirconium cladding, fission and activation products or even solidifiers, which are characterized by reprocessing themselves. In such a case, the amount of nuclear waste that needs to be disposed is reduced significantly.
Current State of Nuclear Reactors and Technology Development
In various countries, the growth of nuclear power has been characterized by the evolution of technologies and designs of both domestic as well as imported reactors. The basic principles for using nuclear power reactors in producing of the electricity are just the same for almost all types of nuclear reactors (Kolarik & Renard, 2003). The energy is released from a continuous fission of atoms of the nuclear fuel. This energy is harnessed as the heat in either water or gas form, which is later used to produce a steam. This steam is then employed to turn on turbines which, in turn, produce the electricity. With regard to the spent fuel, a lot of technologies have been developed. These technologies cover varying dimensions with regard to the spent fuel. Some argue on the basic disposal measures of the fuel, while others capture the recycling and reprocessing processes of the spent fuel. The nuclear reactors being used today derived their basic designs from the propelling of large naval ships and submarines. The main nuclear design being currently used is the pressurized water reactor (PWR) (Paiva & Malik, 2004). This reactor contains water which is heated to the temperature of approximately three hundred degrees centigrade.
The main components of current nuclear reactors include:
- Fuel: the basic fuel being currently used in many reactor designs is uranium. Pellets of uranium oxide are arranged in some tubes. These tubes are then used to form fuel rods. In the reactor core, the rods are attached to fuel assemblies.
- Steam Generator: this is contained in a part of the overall cooling system of the pressurized water reactors. A high-pressure coolant which brings the heat from the reactor is used to make a steam which is subsequently used to turn on the turbines.
- Control Rods: these control rods are usually made with some materials, which are able to absorb neutrons. These materials may include hafnium, cadmium and boron and are either withdrawn from or inserted in the core (Kolarik & Renard, 2003). This is done in order to control the rate of reaction or even halt it. However, some technologies have special control rods, which enable the core to sustain substantially low levels of power in an efficient manner.
The international trend being witnessed currently and which seeks to expand the spent fuel storage capabilities has brought about significant improvements of the proposed systems (Paiva & Malik, 2004). These new technologies have to accommodate the spent fuel assemblies, which are usually characterized by the increasing thermal releases as well as the total inventory of the spent fuel. The dry storage system has been significant in terms of boosting the spent fuel storage technologies across the world. The main features of this technology include: multiple containment barriers, safe handling operations, low construction costs, low operating costs and passive cooling. The vault type storage system is specifically excellent in providing the effective and efficient storage facilities for keeping the spent fuel (Kolarik & Renard, 2003). This combines the passive safety with a large capacity which can allow a quick amortization of the spent fuel receiving equipment. Additionally, the versatile storage position is able to accept different types of fuel. It can also accept a considerable amount of the spent fuel.
The remote technology applications have also been highly useful in the spent fuel management. Currently, the remote system technology can offer more than a manipulator technology. This technology also provides a higher degree of freedom (Paiva & Malik, 2004). There is large variety of remote systems which have simpler mechanisms and have been developed and used widely for different purposes. There has been a trend in the evolution of the remote technology, focusing on the fission in the technical application between non-nuclear and nuclear areas. The main factor behind this trend has been the shrinking market of the nuclear sector. Additionally, the trend can also be considered as driven by the expansion of the application of advanced technologies in such spheres as communication, informatics and robotics.
The management of the spent fuel has become a considerably prospective and potential area for the application of a remote technology, especially in the last few years. This is due to the increase in the inventory of the spent fuel in nuclear power reactors. The remote technology usage in the spent fuel management can be seen as the one that has matured substantially in the past decades of industrial experiences. Additionally, there has been a development of a considerable number of various remote technologies. Those technologies have specifically focused on the spent fuel examination, reprocessing, transportation, storage and radioactive waste treatment. Industrial practices have seemed to make use of the simple but robust designs for the most of those technologies in the field of the spent waste management. In this regard, it allows ensuring that the spent waste is recycled and reprocessed in the correct manner, while at the sometime, contributing towards a situation ,where the nuclear waste is minimized (DoE, 2002).
Currently, services as well as equipment needed in terms of the remote technology are readily available in the market for the application in most projects in the field of the spent fuel management. Some extensive applications of the remote system technology are most likely to become possible in future. This is due to the fact that innovative nuclear systems have recently attracted a growing interest in the search for both a sustainable and safe nuclear energy (Kolarik & Renard, 2003). This has also been made possible by the recognition of the potential of nuclear energy and spent fuel processing in new economies in the world. Therefore, current technologies are seeking for initiatives which can address the question of future energy requirements as well as sustainable utilization of the nuclear energy in a way that will significantly minimize the nuclear waste.
Advantages, Disadvantages and Limitations of the Source
As a source of energy, the spent fuel has some advantages, disadvantages and limitations, as well. In this regard, the following section discusses the abovementioned aspects related with the further implementation of the spent fuel.
The spent fuel is renewable; hence, it can be used for a long period without running out. This is due to the fact that the spent fuel is made up of small radioactive isotopes which have a substantially long half-lives. Therefore, it takes a lot of time before this energy is completely depleted. With a proper process of reprocessing, the spent fuel can be used for several years, hence making it a sustainable form of energy. Additionally, the spent fuel is able to produce considerably more energy as compared to other sources of energy such as the hydroelectric energy (Bruno & Ewing, 2006). This is because of the rapid and massive heat that is produced during the fission process. Being renewable, this form of energy requires less maintenance as compared to the traditional generators of energy. Similarly, it is cost effective to a considerable degree. This is due to the fact that this form of energy is obtained as a result of the recycling process. The spent fuel is primarily a product of nuclear waste; as a result, using the spent fuel as a form of energy does not cost as much as other forms of energy do. Additionally, using it is crucial in reducing the environmental destruction; whereas the majority of other forms of energy are responsible for the environmental degradation. For instance, energy from petroleum products leads to a severe environmental damage (Bruno & Ewing, 2006). Meanwhile, recycling of the spent nuclear fuel ensures that harmful and toxic elements are not released into the environment. Thus, it guarantees that the ecology of the world is not adversely affected.
The abovementioned source of energy is associated with radioactive elements, which if released into the environment can be harmful and highly dangerous to human beings. The radioactive elements are cancerous to a considerable degree; hence, they require a lot of protection in order to ensure that they do not reach the environment. Due to this, constructing of power plants requires many resources that in most instances cost millions of dollars (Paiva & Malik, 2004). These power plants must be fitted with protection materials, which ensure that both operators in the plant as well as the outside environment are not exposed to dangers. In case of fire breakouts, nuclear reactors may lead to a massive disaster. In instances, where such a disaster occurred in the past, the consequences were highly devastating, resulting in destroying of a lot of property, killing and displacing people. Therefore, this source of energy demands a specific approach and a lot of care in its handling (Kortelainen et al., 2010). Disposing of the waste from the reactions also requires a significant amount of investments as the waste products are harmful and toxic to a substantial extent. Additionally, reprocessing can lead to potential nuclear terrorism, which is a dangerous issue, especially during this particular period of time, when terrorism has become a security concern on a global scale (Bruno & Ewing, 2006).
Recycling this form of energy requires a lot of expertise and skills which workers in most countries may not be able to acquire. For instance, the technology required in the storage of the spent waste is quite complicated. Thus, the developing economies may not be in a position to acquire a specific equipment that is necessary in this regard. Therefore, this leaves these countries with no option, rather than having to use the traditional forms of energy (Paiva & Malik, 2004). In general, the use of nuclear energy requires the precise adherence to specific stipulated standards which must be followed by all facilities containing nuclear reactors. In some countries, especially the developing ones, these standards are a burden and hard to fulfill. As a result, these countries are deprived of the possibility to use this source of energy.
Solution and How We Can Use It
To obtain the maximum energy value from the used nuclear fuel, there is a need to reprocess it. Typically, a nuclear reactor will generate approximately 20 tons of the used nuclear fuel every single year. Out of these 20 tons, there are approximately 200 kilograms of plutonium. However, this is often misunderstood by many opponents who argue that the isotopic mixture of this plutonium is suitable for the manufacture of nuclear weapons (Kolarik & Renard, 2003). However, it is worth mentioning that high costs that are required to reprocess the plutonium to nuclear weapons make it quite impractical. Therefore, it becomes essential to utilize the type of energy that is obtained from the process of recycling and reprocessing.
The nuclear reprocessing technology was typically developed in an effort to efficiently and ultimately recover the fissionable plutonium from the irradiated nuclear fuel. Reprocessing of the spent fuel serves multiple purposes. However, the relative significance of these aims changes over time. In the initial stages of this technology’s development, reprocessing was solely done for extracting the plutonium in order to use it in the manufacture of nuclear weapons. Nonetheless, this has changed over time. With the recent commercialization of the nuclear power, the reprocessed plutonium has been recycled into the nuclear fuel for a continued use in thermal reactors. The reprocessed uranium, which ultimately contains huge volumes of the spent fuel material, can be used as a reused fuel (Kolarik & Renard, 2003). However, this is only relevant if prices of uranium are extremely high. A typical facility with a nuclear reactor is not in any way restricted to using the recycled uranium or plutonium, which the spent fuel contains. Additionally, it can also make use of all the actinides, hence closing the nuclear fuel cycle. This can potentially multiply the kind of energy extracted from the natural uranium by approximately sixty times.
Reprocessing of nuclear fuel is instrumental in reducing the amount of high-level nuclear waste. However, by itself it does not significantly reduce the radioactivity or even the heat generation (Menyah & Wolde-Rufael, 2010). This reason makes reprocessing not able to eliminate the need of having to use the geological waste repository which has been in use for several years. Reprocessing of the spent fuel has been an issue of political debates for a couple of years now due to the potential of the spent energy to contribute to the nuclear proliferation. Similarly, the vulnerability to dangerous issues, such as nuclear terrorism, and the high cost further make reprocessing a debatable issue. However, nuclear reprocessing is highly essential in ensuring that nuclear waste is reduced significantly.
Currently, the global capacity of reprocessing the spent fuel is approximately 5600 metric tons (Kortelainen et al., 2010). There are two main ways, through which the spent fuel can be converted to energy. The first method, which is the most common one, is to use the reprocessed material in order to make fuel which can be used for both light and heavy water reactors. The other way of doing it is to produce the first electricity from the nuclear reactors. The second option is usually more efficient as compared to the first one. Mixed oxide fuel (MOX) assemblies are then used to replace the traditional enriched uranium fuel in the light water reactors.
Can Spent Fuel Be Recycled?
With the required technologies, the spent fuel can be recycled. This is done by reprocessing the nuclear waste for it to be used in the nuclear reactors again. Therefore, recycling of the spent fuel sounds as a substantially promising solution. However, it is worth noting that the process itself has received many criticism. The most common opinions emphasize that the process is quite expensive, dangerous and faced with numerous technological hardships (Menyah & Wolde-Rufael, 2010). This has been the view of the majority of counties that have been reluctant in funding reprocessing cycles. Even the developed nations, such as the United States, argued the necessity in funding the spent fuel reprocessing projects. The main issue witnessed in terms of the spent fuel’s further implementation is the high cost of doing it in addition to the dangers that the process can expose the environment to.
Future Challenges in Developing This Source
Although it is a quite promising strategy of reducing and most probably eliminating the wastage of nuclear energy, there are some challenges, which are expected in the development of this source of energy. The reprocessing as well as recycling strategy of the spent fuel has been based on the assumption that there will be a rapid growth in the uranium as well as nuclear energy demand. However, the growth in nuclear energy, especially from the onset of the 1970s, seems to be passive to a certain extent (Bunn et al., 2005). The plans for recycling and reprocessing of the spent fuel have, therefore, been downsized significantly. As a result, an increasing number of countries have abandoned the whole process of closed fuel cycle (Kortelainen et al., 2010). This is expected to continue in future, where most countries will focus on the direct disposal of the spent fuel. These challenges are even more serious in regard to the increasing prices of uranium, whereas countries find the nuclear energy more expensive. Additionally, the reluctance of support from the vast majority of countries makes the realization of these recycling goals quite impossible. The selection of the best strategy in terms of the fuel management has become a substantially complicated decision that. This emanates from the fact that the number of factors to be considered have been increasing and are even expected to continue to increase in future. Specifically, this can be seen from the crucial environmental concerns of the global community. Countries have started to seek for more efficient and appropriate energy solutions, which entail exploiting sources such as solar energy.
Role of This Source of Energy in Future
Reprocessing of the spent fuel is expected to be a major booster in attaining the energy levels required by the world in future. In most economies, especially the developing nations, there is an increasing demand for more reliable forms of energy. This is due to the growing number of industries being installed in these countries (Bunn et al., 2005). Such industries are requiring increasingly more energy in order to run them. Additionally, the traditional forms of producing energy have become unreliable. For instance, in parts of the world, such as Africa, there was a lot of reliance on the hydroelectric power, which depended on rains to a considerable degree. However, there has been a significant change in the climatic conditions, which has necessitated countries to seek for more reliable forms of energy (Menyah & Wolde-Rufael, 2010). Many countries are, therefore, expected to exploit this form of energy. Recycling of the spent fuel develop with regard to the increase of the spent fuel’s use. Therefore, it will supplement other forms of energy to a large extent. Additionally, the spent fuel will even compete with other forms of energy, namely petroleum products. This is a result of commercialization efforts aimed at the development of this kind of energy, especially in countries such as Japan.
The Advanced Power Reactor 1400Mw (APR-1400) is an advanced water nuclear reactor that is currently being constructed in the United Arab Emirates (UAE). This pressurized nuclear reactor has been designed by the Korea Electric Power Corporation (Lenzen, 2008). It has been done in a way that increases the safety of nuclear reactors. This project is expected to play a vital role in the United Arab Emirates. Specifically, the APR-1400 is aimed at increasing of the total energy output in the country. This is highly essential considering the substantially raising energy demands in UAE. This reactor will also influence reprocessing of the spent nuclear fuel, hence contributing heavily to the global spent fuel reprocessing capacity.
A key and seemingly unique feature of nuclear energy is that it can be reprocessed as to recover the fissile as well as the fertile materials. This process has the ability of providing a fresh fuel for both existing and future nuclear power plants. Some European countries, such as Russia and the United Kingdom, have developed policies aimed at developing the spent fuel reprocessing technologies. However, in other countries, the spent fuel is still being considered a waste. Most people tend to refer to this kind of energy, which in most cases includes small amounts of plutonium, as a waste. However, it is not the case; on the contrary, it can be seen as a result of the failure of nuclear reactor plants to reprocess or even recycle the spent nuclear fuel. Thus, it becomes a waste of a highly valuable resource. The inability or even the failure to reprocess or recycle the spent fuel is a major waste of nuclear energy. Reprocessing of the spent energy is an enormous source of cheap energy. Additionally, making use of the spent fuel is a crucial step in ensuring that the dangers exposed to the communities are reduced significantly. However, most countries in the world have not installed the correct technologies to initiate reprocessing of the spent fuel. Furthermore, even the countries, which have tried to reprocess the spent fuel, have not been in a position to do this efficiently.