atw - International Journal for Nuclear Power | 10.2020

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atw Vol. 65 (2020) | Issue 10 ı October ENVIRONMENT AND SAFETY 492 Nuclear Energy – Reliable, Safe, Economical and Always Available to Protect the Environment Peter Dyck Introduction The commercial use of nuclear energy (NE) was initially linked to the great expectation of generating enormous quantities of cheap electricity. Various technologies were therefore developed, starting with reactors based on natural uranium. Many countries, however, concentrated on reactors with enriched uranium to achieve even higher power densities. Nuclear power plants worldwide were designed and constructed on this basis. At that time in Germany, for example, the SPD in particular campaigned for around 50 nuclear power plants. Mainly in western countries, the emphasis was placed on high safety standards from the very outset. As time went by these standards were raised higher and higher. Naturally, the consequence was further increases in specific costs. Increasing the capacity and thus the size of the plants was seen as an initial solution to reducing them. There were also repeated demands for inherently safe plants. Different approaches and concepts, such as Generation III, Generation III+ and Generation IV, brought this goal closer and closer. In the 2000s, the construction of new nuclear power plants was also influenced by another aspect, namely the reduction of CO 2 emissions from electricity generation. The reason for this was the conviction that CO 2 released by humans would contribute massively to global warming. It quickly became clear, however, that the socalled renewable energies (wind and solar energy), which were promoted from 2000 onwards, could only supply weather-dependent power and were not sustainable with respect to the entire electricity system. Permanent back-up provided by fossil fuel or nuclear power are required. In Germany, these back-up systems were made more expensive due to the prio ritization rule of the Renewable Energy Sources Act. The renewable energies were unable to contribute to grid stability, not to mention the costs. It is therefore impossible to provide a secure power supply for industrialized countries with wind turbines (off and on-shore) and photovoltaic installations. These and other serious disadvantages were the trigger that brought the focus of interest in various countries firmly back to nuclear energy. SMRs (small modular reactors, Generation IV) are now being developed as a near inherently safe design concept for small countries and a decentralized power supply. They include gas-cooled (He) reactors with up to 300 MW installed capacity. The idea is based on a uniform design, a standard approval procedure and standardized components, combined with a reduction in costs. In each case, the plants can be adjusted to the demand (electricity, sea water desalination, process heat) by constructing several modules. They would be particularly suitable for use in combination with renewable energies as they can be switched on and off quickly. The dual fluid reactor (DFR) is emerging as a new development. This reactor works with a liquid fuel mixture and a metal coolant. As a fast breeder reactor, it can fission all uranium and plutonium isotopes as well as all transuranic elements and breed fissile material. In each case, the fission products are separated and sent for ultimate waste disposal, while transmutation is still carried out for a number of isotopes. This results in significantly lower requirements for the proof of long-term safety of a deep geological repository of some 500 to 1,000 years instead of one million years. In this way, it is also possible to use spent nuclear fuels from light water reactors (LWR). As a result, an enormous amount of fissile material is available, especially since Th-232 could also be used. The policy adopted by many countries of choosing longterm interim storage for their spent fuel assemblies is now proving to have been right. Current situation A number of the many nuclear power plants that were built in the early years have already ceased operation. Either because the design or size of the plant did not meet economic requirements, or because technical problems made decommissioning appear advisable, or because the plant had simply reached the end of its service life. The reactor accidents of Three Mile Island (1979, in Block II) and Chernobyl (1986, Block IV), which resulted in the decommissioning of nuclear power plants, had an additional impact. In Italy, it was even decided to abandon the nuclear energy supply completely. Further shutdowns followed the tsunami in Japan due to the problems associated with it, such as failure of the electricity supply and oxyhydrogen gas explosions in the old, poorly secured Fukushima reactors. Thereupon, in Germany, for example, eight reactors were forced to shut down for political reasons. At the same time, the decision was also taken to phase out nuclear energy completely by 2022. The three most modern rectors Isar 2, Emsland and Neckarwestheim 2 will be shut down for decommissioning at the end of 2022. In other countries, on the other hand, safety systems were reassessed and, where necessary, upgraded. With its “international best practices in the ageing management of nuclear power plants”, the International Atomic Energy Agency (IAEA) supports its member states in extending the service life of nuclear power plants by a further 20 to 40 years while continuing to guarantee the highest possible level of safety. [1] The IAEA coordinates collaboration between the member states in order to adopt best practices. The program deals with the physical aging of systems, structures and components as well as technical progress. It also incorporates the results of the Electric Power Research Institute (EPRI), which cooperates with the IAEA. Recently, however, new nuclear power plants have been commissioned Environment and Safety Nuclear Energy – Reliable, Safe, Economical and Always Available to Protect the Environment ı Peter Dyck
atw Vol. 65 (2020) | Issue 10 ı October | Fig. 1. Global power generation from NPPs since 1956. (Source: VGB Facts & Figures I Electricity Generation 2020/2021) again in various countries, particularly in Russia, Asia (China, India, Pakistan, etc.) and in the United Arab Emirates. The current situation shows that the nuclear power plants in operation (32 countries operate nuclear power plants) are distributed relatively unevenly across the globe. Measured in terms of the share of nuclear energy in total national power generation, France is the most important country in the world with around 72 percent and the United States still is it with regard to the number of power reactors operated. One special case is module designed as a floating nuclear power plant – Akademik Lomonosov – with two prototype reactors of 38 MW electrical output (MWe) and 150 MW thermal output (MWth). These “ floating reactors” were taken to the port town of Pevek, in the far north of Russia, where they will replace the Bilibino power plant. [2] Oil 193.03 33.1 % Coal 157.86 27.0 % Natural gas 141.45 24.2 % Hydropower 37.66 6.4 % Renewable energy Nuclear energy Looking at the total primary energy consumed worldwide, the following picture emerges: Total consumption in 2019 was around 583.9 exajoules or around 162,324 TWh, broken down by energy source as shown in Table 2. On average, it can be expected that around 25% of primary energy is used for electricity generation. Global electricity generation in 2018 stood at some 26.600 TWh, 64 percent of which was generated USA 95 Pakistan 5 France 56 Slovakia 4 China 49 Finland 4 Russia 38 Hungary 4 Japan 33 Switzerland 4 South Korea 24 Argentina 3 India 22 Bulgaria 2 Canada 19 Mexico 2 Ukraine 15 Romania 2 United Kingdom 15 Brazil 2 Belgium 7 South Africa 2 Sweden 7 Slovenia 1 Spain 7 Iran 1 Germany 6 Armenia 1 Czech Republic 6 Netherlands 1 25.83 4.4 % 24.16 4.1 % Other 4.71 0.8 % | Tab. 2. Consumption in exajoules, 2019, various energy sources [3]. | Tab. 1. Number of nuclear power plants operated worldwide; status mid-2020 [3]. with the fossil fuels coal, natural gas and oil while 36 percent was generated low-carbon: 16.2 percent hydropower, 10.1 percent nuclear power and 9.8 percent with wind and solar power, biomass, waste, geothermal energy and tidal power. The following picture Figure 2 emerges for Germany, where primary energy consumption has fallen sharply since 1990. Nuclear power plants under construction In contrast to Germany and Switzerland, the dominant nuclear energy countries continue to invest in this resource-saving and environmentally friendly technology. For example, 52 nuclear power plants were under construction worldwide in mid-2020. There are sound reasons for the construction of new nuclear power plants: a) nuclear power plants from the boom of the 1970s will be ENVIRONMENT AND SAFETY 493 1990 2019* 5.228 PJ 35 % 2.304 PJ 15 % Total 14.905 Petajoule 1.668 PJ 11 % 199 1 % 3.201 PJ 21 % 2.306 PJ 15 % Hard Coal Brown Coal Mineral Oil Gas Nuclear Energy Renewables and other energy sources 2 4.519 PJ 35 % 3.200 PJ 25 % Total 12.815 Petajoule 820 PJ 6 % 1.170 PJ 9 % 1.886 PJ 15 % 1.134 PJ 9 % 86 PJ 0,7 % Hard Coal Brown Coal Mineral Oil Gas Nuclear Energy Renewables Other energy sources 2 | Fig. 2. Primary energy consumption 1 by energy sources, FRG, cf. 1990 with 2019. 1 Calculations based on the efficiency approach; 2 Until 1999 renewable energies with other energy sources, separate recording from 2000 on other energy sources are: non-renewable waste, heat and foreign trade balance from district heating and electricity; * preliminary information; Source: for 1990 Federal Environment Agency based on AG Energiebilanzen, Evaluation tables for the energy balance for the Federal Republic of Germany 1990 to 2018 as of 10/2018; for 2019 Federal Environment Agency based on AG Energiebilanzen, primary energy consumption as of 12/2019 Environment and Safety Nuclear Energy – Reliable, Safe, Economical and Always Available to Protect the Environment ı Peter Dyck
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atw - International Journal for Nuclear Power | 10.2020

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