The “new king” in global power generation is photovoltaics, as the International Energy Agency recently stated in its annual report 2020, but at least some countries see it continue to have a future in nuclear power. This includes, for example, the USA: Here the Department of Energy (DoE) has just received the first 160 million dollars for the construction of two new types of power plants released, which should run from the end 2027. A total of several billion dollars in funding is possible for this – and one of the two new reactors could be a good addition to more and more electricity from the sun and other renewable but unstable sources.

The two companies that are now receiving DoE funding as part of the Advanced Reactor Demonstration Program, which started in spring, are young, but still old acquaintances in the nuclear scene: Terrapower was 2006 founded by Bill Gates and others and already got 2016 together with the partner Southern Energy 40 Million dollars for the further development of a new reactor design. And also X-energy, founded 2009, was already 2016 by the DoE with the same amount

In the USA, too, the ongoing projects for new nuclear power plants are repeatedly delayed or have been completely stopped, but the country has said goodbye to the further development of technology Not. In an article on the new funding for Terrapower and X-energy, the DoE even seems to want to signal something like a spirit of optimism: After decades, the USA is finally ready to take the next step in demonstrating advanced reactors, it says . There is non-partisan support for this in the US Congress, and the two projects could receive 3.2 billion dollars in total.

Wherever the funds go Half of the money goes to the two funded companies, which in turn have to contribute the same amount of funds. The aim is for each of them to build a reactor with a new design that will be “fully operational” within seven years, as the DoE explains (in another communication, however, it speaks of “can”). The payment of the remaining planned funding depends on further allocations from the Congress as well as on satisfactory progress in the period up to 2027.

Both of the designs now funded are different from today’s nuclear power plants, but have been researched and developed in some cases for decades with setbacks. X-energy wants to build a so-called pebble bed reactor in which the uranium fuel is encapsulated in graphite balls. A larger supply is used up very slowly.

The X-energy concept also has two other special features. Instead of water, helium is used for cooling and heat transfer, which enables higher steam temperatures and thus efficiency. And the reactor Xe – 100 is modular and will later be prefabricated in factories; For the DoE project, four units with a total of 320 megawatts of power are planned.

Liquid salt in the tank Terrapower, in turn, is working, together with its partner GE-Hitachi, on a fast reactor cooled with sodium (after the English name, abbreviated as SFR) . The metal only melts at high temperatures, so it does not have to be under pressure, which reduces complexity and costs. As usual with SFR, the resulting heat is transferred to another molten medium, namely salt. This non-nuclear part is decoupled from the actual reactor at Terrapower and can therefore be designed and built less expensively.

In addition, the heated molten salt can not only be used immediately to generate electricity in the generator, but also later – alternatively, it can be stored in tanks first. The actual reactor output for the planned Terrapower demonstrator is 345 M