First spent fuel dry storage facility in Ukraine celebrates its 20th anniversary
20 years ago, on July 16, 2001, the State Nuclear Regulatory Inspectorate of Ukraine issued a license for the commissioning of the first in Ukraine spent fuel dry storage facility (SFDSF) at the Zaporizhzhya nuclear power plant, and on July 18 began loading the first container. This event brought the domestic nuclear industry to the next level.
Globally, the storage of spent nuclear fuel (SNF) from nuclear power plants envisages the construction of permanent long-term storage facilities that should provide this storage for thousands of years until the fuel loses its residual radioactivity. However, as long as there is no full-fledged storage facility designed for such service life, and spent nuclear fuel accumulates, it must be stored somewhere.
In Soviet times, the design solutions of nuclear power plants with VVER-1000 reactors provided that the spent nuclear fuel after three years in special fuel storage ponds will be transported to a stationary storage facility in Russia. However, it soon became clear that due to the lack of opportunities to either expand this storage facility or build a spent nuclear fuel reprocessing plant, the viability of nuclear power plants could be significantly reduced.
For the largest in Ukraine and Europe Zaporizhzhya NPP, experts predicted a rather disappointing scenario. Due to the filling of the fuel storage ponds, the units of the nuclear power plant would have to be shut down before 1998, leaving a quarter of the population and enterprises of Ukraine without electricity. Therefore, the Ministry of Energy of the USSR adopted a resolution on the construction of the spent fuel storage facility at ZNPP. The project provided for use of transport containers, and was even implemented, but after the collapse of the Soviet Union, it was considered hopeless and scrapped. 10 purchased containers remained spare.
Moreover, in 1993-1995, when Russia imposed a moratorium on the import of spent fuel and its shipment was suspended, problems began to maintain the viability of the power plant and there was a threat of complete shutdown of all its units. In this situation, there was only one way out – to construct its own spent nuclear fuel storage facility within the ZNPP industrial site. This is exactly what its general director Volodymyr Bronnikov insisted on (now he is the President of the Ukrainian Nuclear Society, an Advisor to the President of NNEGC Energoatom, an Honoured Power Engineer of Ukraine).
It is worth noting that «spent nuclear fuel» is a bit of a misnomer. In physics, as explained by Mr. Bronnikov, the term «irradiated nuclear fuel» is used. Now the whole world is preparing to use a certain percentage of spent fuel for electricity production in new generations of reactors. Therefore, each state tries to keep it «at home». In general, dry container storage of spent fuel is a widely used practice in the world, which is also successfully used by Canada, Germany, Switzerland, Great Britain and Lithuania.
Then, in the 1990s, in agreement with the State Committee of Ukraine for the Use of Nuclear Energy Zaporizhzhya NPP announced an international competition for the best project for temporary storage of spent fuel. After careful analysis, the one proposed by the US company Duke Engineering & Services (DE&S) jointly with Sierra Nuclear Corporation (SNC) was recognized as the best and selected. First, because the project has already been implemented at several nuclear power plants, so its reliability and operational safety have been proven in practice. The technical characteristics of the fuel assemblies of VVER-1000 reactors operating at ZNPP correspond to the US PWR, while the possibility of performing all operations on loading and sealing of containers in the reactor compartments of power units minimizes the risk of radioactive contamination.
It was referred to the technology of intermediate storage of spent fuel assemblies in special ventilated containers on a concrete platform. This is the VSC-VVER system, which is a direct modification of the intermediate storage system, licensed and used at US nuclear power plants. The possibilities of using the existing equipment of power units, production of containers at the enterprises of Ukraine, their relatively low cost were also taken into account.
The American side's consent to provide the technology almost for free – as aid – also played an important role. Furthermore, the Americans provided a specially designed and manufactured transporter for moving containers, the cost of which is estimated at one million dollars. In addition, a representative of ZNPP was dispatched to the DE&S office in Charlotte (Mecklenburg County, North Carolina, USA) for the entire period of the project, which began in 1996. By the way, he was the current head of Energoatom Petro Kotin.
Licensing of the project lasted 5 years, it passed 13 rigorous, most scrupulous examinations, for which more than 270 documents were submitted with a total volume of more than 5 thousand pages. Many documents have been reviewed repeatedly, corrected, revised…
In total, the SFDSF complex of the Zaporizhzhya nuclear power plant is designed for 380 ventilated storage containers of 144 tonnes each, which can accommodate more than 9,000 spent fuel assemblies. The storage facility will be cable to store spent nuclear fuel for the entire period of ZNPP operation, taking into account the extension of the service life of power units. Currently, there are 167 containers in the SFDSF.
20 years of the SFDSF operation have proved that all previous calculations regarding its safety were correct, and the quantitative indicators and values for most of the controlled parameters are even much lower than the designed limit values. The economic costs of construction the storage facility were justified: the annual savings in foreign currency due to the refusal to export spent nuclear fuel to Russia and the introduction of its dry storage system is about $ 40 million, and today ZNPP is the most resilient to external crises power plant.
In addition, one of the latest news about the ZNPP SFDSF is its further «ukrainization»: soon absorbing inserts for containers will be mass-produced at Atomenergomash, whereas previously they were ordered from abroad. This technology is available in only five countries around the world, and now in Ukraine as well.