Nuclear Energy Needs a Turning Point Soon

Abstract

In April 2014, I attended the ASME Small Modular Reactor (SMR) Symposium in Washington, DC. It was an excellent meeting with a very positive vision of the future of SMRs. However, there was little emphasis given to the urgency for the revival of nuclear energy in the United States. As an ASME Fellow Member, I am concerned that we are running out of time for building new nuclear power plants including inherently safe SMRs.Figure 1 shows the past and potential future of the U.S. nuclear power generation [1]. In the 1970s to 1990s, we were building nuclear power plants and reached roughly 19% nuclear power of the entire electric power demand. If this trend had not been stopped, today we would have produced about 25% of the total power demand in nuclear power plants, and if this trend would have continued, we would have reached 39% in 2040. This is still much less than roughly 80% nuclear power presently provided of the total electric power demand in France. No wonder that the carbon dioxide discharge per person in France is half of ours in the U.S.Since the early 2000s to about 2020, the nuclear power supply is expected to remain at 19% of total power production. If we do not wake up, old nuclear power plants will be retired and if no new nuclear plants are built, the remaining plants in the U.S. will only provide about 8% of our total electricity demand by 2040. If we start building nuclear plants now in a trend like in the 1970s to 1990s, we could reach 29% of our demand; however, this also requires the additional replacement of the old nuclear power plants. The loss of roughly 11% power generation by the shutdown of old nuclear power plants would be a large loss of green carbon-dioxide-free power generation, since nuclear power plants provide more than the half of all our green electricity.In the past, especially during the Cold War, more small nuclear reactors for submarines, aircraft carriers, icebreakers, and other ships were built than large reactors for power plants. These small reactors went all over the globe, even underneath the ice at the North Pole. Ships with nuclear reactors are in harbors and shipyards; they have to be maintained, repaired, and the reactors refueled. Such small reactors or modifications of them, if inherently safe, could also be used to generate electric power, especially for remote locations, to avoid high fuel supply and electricity transmission costs.SMRs should also be specifically used by industrial users, which currently use a large amount of fossil fuels for providing not just electric power but high-temperature heat. Most industrial processes could be clean by switching to SMRs for supplying process heat and electric power. An example is shown in Fig. 2, where a high-temperature gas-cooled reactor (HTR 250) provides heat at a temperature of 950°C (1740°F) and steam for an extraction turbine. The 65 kg/s (0.52 Mil.lb/h) helium can be used in a heat exchanger or steam reformer. The helium discharge temperature of 680°C (1200°F) can provide 50 kg/s (0.4 Mil.lb/h) main steam at 140 bar/540°C (2000 psi/1000°F) to the turbine. The turbine generator can provide a maximum of 50 MW if no steam is used for a specific application. However, main and/or extraction steam can be provided specifically for a high-temperature hydrogen production process or any other chemical processes [2].Combinations of the inherently safe HTRs with any specific industrial processes can be developed. Detailed designs of such combinations should be finalized and could become available now, because of the experience already gained with the HTR design. In 1984, a combination of an HTR 200 with a coal-to-gasoline conversion system was designed and ready to start the permitting procedures, but was stopped because of the antinuclear trend in Germany after Chernobyl. However, in China at present, two HTR 250 units are in their start-up phase.As we have seen in Fig. 1, we have only limited time to revitalize the nuclear power industry within the next couple of years. We cannot just wait and witness nuclear power generation rapidly decreasing in the U.S.