The Indian civil nuclear energy programme is unique in the sense that it has opted for closed fuel cycle programme with an added stress on nuclear waste reprocessing. As India broadens its nuclear reactors’ base it will need to deal with increased amount of high level waste after reprocessing, which at the moment is not a big concern.
Spent fuel contains 97 per cent of unused uranium and trans-uranium substances that add to long term waste if not reprocessed. Reprocessing removes the uranium and trans-uranium elements from the spent fuel and recycled back into the nuclear fuel cycle for fission reaction for energy generation.
India’s spent fuel management strategy comprises a closed fuel cycle strategy comprising of reprocessing of the spent fuel, recycling of the reprocessed plutonium and uranium (uranium that has not undergone fission) and disposal of the wastes from reprocessing operations. This allows optimum utilisation of resources especially as uranium reserves in India are considerably low. The other option for processing fuel is through the permanent disposal of spent fuel. However, reprocessing involves 2-3% of radioactivity that is generated in the form of high level liquid waste. Further with a closed fuel cycle, the concern regarding the safety of the high level disposal waste is also addressed by separating actinides from fission product wastes.
India has set up reprocessing facilities to treat spent fuel from reactors. Currently three reprocessing plants are being operated in India – one in Trombay that reprocesses spent fuel from research reactors and two are in Tarapur and Kalpakkam that reprocesses spent fuel from pressurised heavy water reactors (PHWR). Spent fuel transportation to storage facility is carried out in adherence to legal frameworks.
Despite its criticism, India has continued to reprocess spent fuel. There is also a plan to integrate the reprocessing plant with the Integrated Nuclear recycle plant. The project is expected to be up by 2020. The plant is expected to reprocess 400 tonnes of spent fuel from indigenous nuclear power plants.
However, in future, spent fuel reprocessing will only become more challenging as more and more reactors especially PHWR and Pressurised Water Reactors (PWRs) will come up.
Dealing with spent nuclear fuel is a complex process as each constituent of the spent nuclear fuel poses varied challenges during the process of disposition. The plutonium extracted from reprocessing of spent fuel is then used in breeder reactors as fuel to breed U233 and utilise the same for power generation. Following this, the plutonium undergoes fission in order to produce energy. This is crucial as India lacks adequate uranium resource otherwise. Plutonium used as fuel in reactors is crucial as natural uranium in India is scarce and India’s energy demand is on the rise. This importance of plutonium compels India to follow the reprocessing process rather than direct disposal. It must however, be noted that while PHWRs are under IAEA safeguards, the breeder reactors are not under the safeguards.
Not only is reprocessing complex, it is also very expensive as it requires the country to build a fuel cycle infrastructure as market price of natural uranium is low. Moreover, the reprocessing process does not prevent the need for storage and also disposal of radioactive wastes. Not all countries are involved in spent fuel reprocessing. Some countries like Germany, the United States and Sweden indulge in direct disposal than on spent fuel reprocessing. Countries like India and Russia continue to follow the reprocessing path. In fact, Russia also imports spent fuel from countries like Iran as requirement in the Joint Comprehensive Plan of Action (JCPOA) in 2015.
It is a known fact that India has three staged nuclear programme and the third stage involved thorium based reactors. However, thorium is expensive and does not undergo fission to produce energy as it is not a fissile material. In addition, there is a lack of adequate uranium to convert thorium into fissile form. Moreover, thorium based reactors are only at its developmental stage. The plutonium reprocessed at the moment thus adds great value as fuel in reactors and for future reactors as well. Even for thorium based reactors, the plutonium isotope 239 can help thorium to be transmuted to U-233.
In India, according to Department of Atomic Energy (DAE) the spent fuel is not disposed of. “The discharged spent fuel from reactors is stored in spent fuel storage bay either at reactor site or at reprocessing facilities. All the spent fuel storage bays are adequately designed” for preventing accidents.
Generally the spent fuel that is immediately discharged from the reactors is temporarily stored at the reactor pool. When the spent fuel is cooled, it is transported to storage locations. India has gained expertise in design, construction, operation and maintenance of spent fuel wet storage facilities and has also undergone the International Atomic Energy Agency (IAEA) conducted Coordinated Research Programme on ‘Irradiation Enhanced Degradation of Materials in Spent Fuel Storage Facilities.’
India has experience in spent fuel reprocessing through the PUREX process that almost completely recovers uranium and plutonium. An advantage with the PUREX process is that because it reduces the uranium consumption, it also reduces the long term radio-toxicity of high level waste as they are capable of burning high level waste through their ability to burn the major actinides- uranium and plutonium and the long lived minor actinides that include neptunium and americium which are economically affordable. Also salt free reagents have further made it easy for India to reduce the toxic waste.
Post 2009 Indo-US nuclear deal, in 2010, signed a reprocessing agreement with the United States that allowed India to reprocess the nuclear materials of US origin operating in Indian reactors that helps to reduce spent fuel stored. In fact, it is the desire to reduce spent fuel stored that has made South Korea desire for a similar agreement with the United States. The US agreement with India has raised criticism over favouritism. However, it must be noted that India has proved a great non-proliferation track record and is also working towards proliferation resistant technologies therefore, deserving not only the spent fuel reprocessing agreement but also the Nuclear Suppliers’ Group (NSG) waiver.
(The author has been writing on various aspects of nuclear power generation. She has been regularly contributing to reputed publications like Washington Quarterly, Comparative Strategy, Federation of American Scientists, RUSI and European Security and Defence to name a few.)