Introduction
Nuclear energy generates over 11 percent of the global total electricity currently (Nilsson par. 1). It produces clean energy without greenhouse gases. That is, nuclear power does not contribute to global warming and related negative consequences. Nuclear energy can produce much energy to meet household and industrial needs. It is superior to other forms of energy in terms of power efficiency. Nuclear energy, however, has received criticism from various sources, but notably environmentalists and other rights bodies. Some of these claims however lack any scientific evidence. Nevertheless, the most critical legitimate challenge is the issue of managing spent nuclear fuel with elements such as (Uranium) /Pu (Plutonium) /Am (Americium). These chemicals are regarded as highly toxic. These are waste by-products from the spent nuclear fuel and therefore they require immediate removal from the plant and then replacement with fresh supplies to ensure constant power production.
Nuclear energy has an exceptional characteristic relative to other forms of fuels. The spent nuclear fuel can still be reprocessed to produce fissile and viable materials, which can be utilised further to generate fresh fuel for available and other future nuclear reactors. Currently, many advanced countries such as the US, European countries, Japan and Russia among others with nuclear power plants have introduced different policies to enhance further utilisation or reprocessing of spent nuclear fuel. However, some countries have failed to account for reprocessing technologies in their policies. The Union of Concerned Scientists has defined reprocessing as “a series of chemical operations that separates plutonium and uranium from other nuclear waste contained in the used (or “spent”) fuel from nuclear power reactors” (Union of Concerned Scientists par. 2).
For the last half a century the primary reason for reprocessing spent nuclear fuel is to recover unused or unspent uranium, plutonium and americium among other chemicals. These materials are used in the generation of energy in nuclear reactors. However, unspent uranium and plutonium can further be reprocessed to generate additional energy and enhance optimal usage and energy security. Another reason that has facilitated the need for reprocessing or further utilisation is to reduce the volume of spent nuclear fuel that goes into land sightings. These are mainly high-level waste (HLW) materials, which account for a significant percentage of land siting materials. Moreover, after reprocessing, the volume of toxic materials contained in the waste is significantly reduced and decline further after several years.
The above-mentioned reasons to reprocess spent nuclear fuel are based on the current state of nuclear power reactors. However, it is believed that the fourth generation of fast neutron reactors in the year 2020s would introduce new ways to ensure that both spent nuclear fuel and stockpiles of used uranium are converted into sources of fuel (World Nuclear Association 1). In fact, technological changes in reprocessing have resulted in increased interests to reprocess and recover all long-lived actinides (consisting of plutonium) so that they can be recycled in fast reactors in order to get fission products with shorter life. Reprocessing is imperative for two critical reasons. It would reduce “the long-term radioactivity in high-level wastes, and reduce the possibility of plutonium being diverted from civil use – thereby increasing proliferation resistance of the fuel cycle” (World Nuclear Association 1). If unspent nuclear fuel is not reprocessed, any protection created to contain radioactivity will naturally weaken and therefore plutonium can be easily mined from sites for illicit activities.
NuclearRUS Challenge
The company, NuclearRUS, currently faces the challenge of managing spent nuclear fuel. The most commonly used material in nuclear power plants is uranium. During the chemical processes, uranium is split, heat energy is released for power production, as well as other several by-products, some of which are extremely toxic for the environment and human. It takes millions of years for waste materials to achieve their half-life status. That is, half of the radioactive molecules will break down into other forms and then release radioactivity. Therefore, disposed spent nuclear fuel can stay for a given period before they can start to release radioactivity into the environment. Some waste elements with shorter life are highly aggressive and contain high rates of radioactivity while others have longer life and can stay for millions of years.
Although a small quantity of high-level waste material is generated relative to low-level waste (LLW) and intermediate-level (ILW), HLW must be handled and stored with a lot of care. Most of the HLWs originate from nuclear power plants.
Every year, it is estimated that a normal nuclear power reactor generates nearly 27 metric tonnes of spent nuclear fuel for power required to provide electricity for about 700,000 household. It is estimated that an average consumer will utilise nearly 11,000 kWh every year while the average capacity for the power is 85%. For coal, about 400,000 metric tonnes of ash will be generated to provide electricity for the same number. In this regard, managing several millions of tonnes from various nuclear power plants is a major challenge to the industry. For several years, deep disposal or burying of waste materials was considered safe. However, this process is complex and influenced by several geological factors. In fact, the best geological sites for high-level radioactive waste materials are required because these materials could be highly volatile and hazardous. In some instances, the best land sitings for spent nuclear fuel are well known globally. Other countries may not have the best geological sites to support deep disposal and therefore they may use alternative means such as exporting these waste materials to other countries. Japan, for instance, has been exporting some of its spent nuclear fuel to the UK.
NuclearRUS has an opportunity to rely on modern developments in reprocessing technologies and future advances to utilise further its spent nuclear fuel. In fact, some nuclear agencies have demonstrated that ongoing changes and use of technologies found in modern nuclear reactors with fast neutron fission capabilities would ensure reliability, sustainability and security for energy supply (World Nuclear Association 1). Further, ongoing studies have focused on tackling much of the waste from reprocessing so that all these materials can be transformed to fuel.
The Solution for NuclearRUS
The best technology for the company to adopt is PUREX (Plutonium Uranium Reduction Extraction). PUREX is currently and widely used in nuclear power plants to facilitate reprocessing of plutonium and uranium and other waste materials from spent nuclear fuel.
A chemical process is involved in the removal of uranium, plutonium and other materials from spent nuclear fuel. In this process, engineers dissolve and treat used nuclear fuel in acid with organic solvents to select and extract plutonium, uranium and other most important materials while leaving other materials behind as waste. As mentioned above, PUREX is the most commonly used in many commercial nuclear power plants.
The US army originally developed PUREX in the 1940s. Over the years however, PUREX technologies have emerged to improve process performances and outcomes. PUREX is not effective in extracting other materials that may be heavier than plutonium (Nilsson 1). Therefore, after the initial waste separation process, some waste materials still need to be separated from other wastes.
It has been proven that PUREX can achieve up to 97 percent recycling of spent nuclear fuel (Nilsson 1). This is a major advantage particularly when the volume of waste reduced is considered. Most of the materials can then be used again as new reactor fuel. The new fuel is a mixture of plutonium and uranium, and it is commonly referred to as mixed oxide or MOX-fuel (Nilsson 1).
Currently, some of the most prominent spent nuclear fuel reprocessing plants can be found in France, the UK and Russia. Although Japan has recently developed a large reprocessing plant, it is not being used perhaps because of the recent nuclear disaster. Indian can also handle some spent nuclear fuel for reprocessing. The US currently does not allow reprocessing of spent nuclear fuel and therefore continues to keep stockpiles for future use. This is rather a political stand rather than any other reason. It argues that technologies can be used to develop nuclear weapons. Every year, it is estimated that “the global reprocessing capacity of commercial fuel is around 4,000 metric tonnes” (Nilsson 1). To present, nearly 90,000 metric tonnes of spent nuclear fuel have been reprocessed and represent more than 30 percent of spent nuclear fuel from commercial power reactors.
NuclearRUS must recognise that investment in a reprocessing plant is extremely expensive. Therefore, once the facility is ready for use, it would receive many clients, including overseas countries that wish to reprocess their spent nuclear fuel.
Glatz (2012) has noted that the latest development in PUREX technology is currently the PUREX2 process.
Another significant process involves the separation of uranium and plutonium with the aim of obtaining at least 99.9% of uranium and plutonium. This method was preferred for NuclearRUS because of its focus on purity of the two elements and other materials with high-level radioactive elements. According to the International Atomic Energy Agency, in PUREX, “both uranium and plutonium may be processed together to avoid obtaining pure plutonium” (International Atomic Energy Agency 1). In this stage, other waste products such as fission elements, actinides and activation contents are “processed and vitrified , i.e. mixed with glass material to form a borosilicate glass, and encapsulated in a steel container” (International Atomic Energy Agency 1).
There are reprocessing practices, which have been provided by organisations to demonstrate how they conduct the process. These PUREX processes could be significantly different depending on the contents and levels of waste materials. Overall, NuclearRUS may use any of the procedures provided by the World Nuclear Association (2015) to separate different elements found in spent nuclear fuel.
- Separate U, Pu, (as today)
- Separate U, Pu+U (small amount of U)
- Separate U, Pu, minor actinides
- Separate U, Pu+Np, Am+Cm
- Separate U+Pu all together
- Separate U, Pu+actinides, certain fission products
The advanced PUREX will deliver an enriched Reprocessed Uranium/RepU) while plutonium will be supplied directly to the mixed oxide for power generation. However, it is noted that this method has two important challenges. First, the purely obtained plutonium remains potentially hazardous because of proliferation. Second, some elements of actinides that remain in the waste materials cannot be complete separated from the two materials. Consequently, the process results in stable plutonium with longer life compared to plutonium combined with fission elements only. The major challenge is that remaining elements of actinides are almost impossible to destroy while light water reactors recycling methods provide only partial waste management advantages (International Atomic Energy Agency 1). It is noted that new advances in technologies would ensure that the PUREX is more effective and able to separate all waste products. PUREX process will destroy actinides with other reprocessed plutonium and uranium in the fast neutron reactors. The fission products with longer life could also be eliminated from waste materials using new PUREX technologies. Once these new techniques and technologies are made available for commercial use, they would provide efficient reprocessing and recycling of spent nuclear fuel. These ongoing developments in PUREX will mark an important milestone in the development of reprocessing and management of spent nuclear fuel.
Therefore, NuclearRUS has the opportunity to utilise PUREX for improved outcomes. It is imperative to note that any new changes must aim to provide reliable processes through reactor systems. That is, new systems should be able to minimise the amount of waste materials discharged while they offer improved extraction methods for all actinides. The outcomes can only be shown in the final discharged contents of spent nuclear fuel reprocessing. The most important development should focus on obtaining a solution for actinide solution (Glatz 343).
The enhanced reprocessing technique should ensure it accounts for the contained aqueous for extraction of elements of actinides. In fact, the ideal situation should lead to extraction of traces of actinides to show that these elements could be removed from the final waste. In addition, an advanced section with diamide or phosphine oxide constituents can be used to separate other minor traces of actinides. The most important part of this process should concentrate on an extremely difficult role of separating “lanthanides from other trivalent actinides” (Glatz 343).
NuclearRUS should only allow specialists to work on the reprocessing because of its complexity, specifically in pyrometallurgy processes (Glatz 343).
It is advisable that NuclearRUS should consider the latest technologies in its nuclear power reactor because of their efficiency and the belief that they can extract and recycle all traces of actinides in the waste materials. These advances are robust and present new opportunities for NuclearRUS and in fact, they have prompted countries such as the US to review their policies on spent nuclear fuel recycling because of the promising outcomes they hold. According to the World Nuclear Association (2015), new technologies and subsequent use found in advanced nuclear reactors built with fast neutron fission capabilities would result in reliability, sustainability and security for energy supply. That is, reprocessing would improve the usability of spent nuclear fuel materials by increasing the amount of power that can be produced from the already used uranium and plutonium. By using an advanced PUREX process, almost all materials with longer life will be separated at the fast reactor operation and therefore only a small quantity of fission product waste materials that require “guaranteed isolation from the environment for not more than 500 years” (World Nuclear Association 1) will be produced.
NuclearRUS must note that new technologies and developments on existing processes require a great deal of collaboration and working together with other experts. On this note, the company will have to cooperate with other nuclear reprocessing plants with the same or superior technologies in nuclear waste management to borrow best practices and enhance the application of more robust proliferation-resistant recycling processes in order to produce more power from waste materials, reduce waste materials for deep disposal and limit chances for proliferation.
Advantages of PUREX reprocessing method over deep disposal
When compared with the direct deep disposal, PUREX has some advantages that are generally attributed to reprocessing benefits. First, the company will be able to reduce the quantity of long-term radioactive hazardous materials significantly and consequently reduce concerns over long-term deep disposal sightings. Second, it is believed that safer practices associated with reprocessing will lead to more public acceptance and change complex siting designs currently required. Third, it has been observed that heavier radioactive waste materials generate a lot of heat. However, when the amount of weight is reduced, then siting would last longer and limit the spread to groundwater aquifer. Fourth, it provides opportunities to generate more energy from spent nuclear fuel. Therefore, waste materials will be recycled and well used for productive purposes. Fifth, critical threats to the environment are generally reduced through PUREX techniques in addition to occupational exposure that is most likely to occur during handling processes. Fifth, it will reduce overall waste quantity because of reprocessing and recycling of all materials. Sixth, PUREX advanced technologies will reduce and simplify reprocessing stages and at the same time ensure optimal outputs. Finally, PUREX provides real time monitoring of spent nuclear fuel. This would ensure accountability for all spent nuclear fuel materials.
While PUREX provides several advantages, some unions and interest groups have opposed any reprocessing activities to protect the environment (Union of Concerned Scientists 1). However, their concerns can be mitigated at the site through enhanced surveillance and accountability.
Comparison of the solution with other alternative techniques
While a comparison can be made against other available alternatives such as DUPIC technique, Super-DIREX (supercritical fluid direct extraction), CARBEX Process, and DIAMEX-SANEX processes among others, PUREX is widely used globally (Hore-Lacy 1). In addition, it is noteworthy that different reprocessing techniques are chosen to meet various needs with several factors such as costs, process complexity, types of hazardous chemicals involved, geological sites, and expertise among others are considered to ensure that optimal results are achieved. Further, developers are known to improve on their inventions and technologies and therefore it is vital that the chosen method meets its intended purpose with minimal impacts on the environment and other variables.
Approval Required for the Proposed PUREX
In the UK, the Office for Nuclear Regulation (ONR) is solely responsible for evaluation of the safety and security of spent nuclear fuel reprocessing technologies and instalments. As a result, ONR will review NuclearRUS system to ensure that PUREX is safe for extraction of uranium, plutonium and Americium. For NuclearRUS to get approval, the ONR must evaluate all available facilities, including “the existing fleet of operating reactors, fuel cycle facilities, waste management and decommissioning sites” (Office for Nuclear Regulation 3) and any other specific activities that relate to the work of NuclearRUS in spent nuclear fuel reprocessing. Moreover, the ONR shall consider “the design, construction of new nuclear facilities, the transport and safeguarding of nuclear and radioactive materials” (Office for Nuclear Regulation 1) to determine if they meet the minimum safety standards expected.
NuclearRUS will work in collaboration with the ONR to ensure that procedures, common concerns and any other issues are sorted out effectively. In addition, if the company wishes to establish a new plant in another European country or outside Europe, it must adhere to set standards, regulation and laws governing nuclear reactor plants in those jurisdictions.
The ONR claims that it works with rigour, diligence and with optimal levels of assurance with regard to the extent of the work and risk levels of chemicals at the facility (Office for Nuclear Regulation 1). Therefore, the proposed PUREX to reprocess spent nuclear fuel for NuclearRUS must meet all the minimum specifications for quality and safety standards before it can be used at the company for reprocessing.
Of course, NuclearRUS must adhere to inspection of the International Atomic Energy Agency. The agency must inspect all reprocessing plants in any jurisdiction to ensure that no chemicals are used for other purposes, including manufacturing of weapons other than nuclear power generation.
Possible costs of the new proposed solution
Cost variations are common in such complex plants and processes. Hence, the real cost of adopting the process can be a major challenge to determine before the implementation. Besides, other factors such as composition of waste materials, operating systems or waste transmutation may influence the overall cost of the plant. Nevertheless, a cost assumption has been made from Bunn et al. (2003) and Kenul et al. (2010) to show costs most likely to be incurred or saved by NuclearRUS when adopting PUREX. These are believed to be for optimal processes.
Estimated reprocessing costs
Note: cost estimated from Bunn et al. (2003) and Kenul et al. (2010)
Conclusion
The amount of energy that can be generated from nuclear reactors is significantly high and can support millions of households and industrial processes. In addition, it offers alternative to other sources of energy that are hazardous to the environment. However, a major issue is management of waste materials from spent nuclear fuel. Consequently, nuclear engineers have developed different technologies to facilitate handling and reuse of spent nuclear fuel. PUREX was chosen for NuclearRUS to ensure that the company can further its U, Pu, and Am from spent nuclear fuel to generate more energy. PUREX will offer some advantages relative to deep disposal. It will limit HLW for deep disposal and guarantee sustainability and security of energy. The chosen alternative is commonly used and has been improved upon for many years. It is therefore suitable for NuclearRUS reprocessing of spent nuclear fuel.
Works Cited
Bunn, Matthew, John Holdren Steve Fetter and Bob van der Zwaan. “The Economics of Reprocessing vs. Direct Disposal of Spent Nuclear Fuel.” 2003. Web.
Glatz, J.-P. “Spent Fuel Dissolution and Reprocessing Processes.” Comprehensive Nuclear Materials 5 (2012): 343–366. Print.
Hore-Lacy, Ian. Reprocessing of nuclear fuel. 2011. Web.
International Atomic Energy Agency. Development of Advanced Reprocessing Technologies. n.d. Web. 2015.
Kenul, Damon, Austin Kesar, Sithara Kodali, Dan Plechaty, Anna Szabo and Ignacio Tagtachian. Nuclear Fuel Reprocessing Future Prospects and Viability. 2010. Web.
Nilsson, Mikael. Harvesting Usable Fuel From Nuclear Waste – And Dealing With The Last Chemical Troublemakers. 2015. Web.
Office for Nuclear Regulation. Office for Nuclear Regulation. n.d. Web. 2015.
Union of Concerned Scientists. Nuclear Reprocessing: Dangerous, Dirty, and Expensive. n.d. Web. 2015.
World Nuclear Association. Processing of Used Nuclear Fuel. 2015. Web.