Energy is a central issue for the future, and we need a positive focus on where we can go. Accordingly, let us consider the Chinese pebble bed initiative:
As a backgrounder, Wiki:
The pebble-bed reactor (PBR) is a design for a graphite-moderated, gas-cooled nuclear reactor. It is a type of very-high-temperature reactor (VHTR), one of the six classes of nuclear reactors in the Generation IV initiative.
The basic design of pebble-bed reactors features spherical fuel elements called pebbles. These tennis ball-sized pebbles (approx. 6.7 cm or 2.6 in in diameter) are made of pyrolytic graphite (which acts as the moderator), and they contain thousands of micro-fuel particles called TRISO particles. These TRISO fuel particles consist of a fissile material (such as 235U) surrounded by a ceramic layer coating of silicon carbide for structural integrity and fission product containment. In the PBR, thousands of pebbles are amassed to create a reactor core, and are cooled by a gas, such as helium, nitrogen or carbon dioxide, that does not react chemically with the fuel elements. Other coolants such as FLiBe (molten fluoride, lithium, beryllium salt)) have also been suggested for implementation with pebble fuelled reactors. Some examples of this type of reactor are claimed to be passively safe.
Because the reactor is designed to handle high temperatures, it can cool by natural circulation and still survive in accident scenarios, which may raise the temperature of the reactor to 1,600 °C (2,910 °F). Because of its design, its high temperatures allow higher thermal efficiencies than possible in traditional nuclear power plants (up to 50%) and has the additional feature that the gases do not dissolve contaminants or absorb neutrons as water does, so the core has less in the way of radioactive fluids.
The concept was first suggested by Farrington Daniels in the 1940s, said to have been inspired by the innovative design of the Benghazi burner by British desert troops in WWII, but commercial development did not take place until the 1960s in the German AVR reactor by Rudolf Schulten. This system was plagued with problems and political and economic decisions were made to abandon the technology. The AVR design was licensed to South Africa as the PBMR and China as the HTR-10, the latter currently has the only such design in operation. In various forms, other designs are under development by MIT, University of California at Berkeley, General Atomics (U.S.), the Dutch company Romawa B.V., Adams Atomic Engines, Idaho National Laboratory, X-energy and Kairos Power.
HTR-10 is a 10 MWt prototype pebble bed reactor at Tsinghua University in China. Construction began in 1995, achieving its first criticality in December 2000, and was operated in full power condition in January 2003.
Two HTR-PM reactors, scaled up versions of the HTR-10 with 250-MWt capacity, were installed at the Shidao Bay Nuclear Power Plant near the city of Rongcheng in Shandong Province and achieved first criticality in September 2021.
More (Wiki here serves simply as a news source):
The HTR-PM (球床模块式高温气冷堆核电站) is a small modular nuclear reactor in China. It is the world’s first prototype of a high-temperature gas-cooled (HTGR) pebble-bed generation IV reactor. The reactor unit has a thermal capacity of 250 MW, and two reactors are connected to a single steam turbine to generate 210 MW of electricity. Its role is to replace coal-fired power plants in China’s interior, in line with the country’s plan to reach carbon neutrality by 2060.
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On 12 September 2021, the first of two reactors achieved criticality. On 11 November 2021, reactor two achieved first criticality. On 20 December 2021, reactor one was connected to the state power grid and began producing power. On 9 December 2022, the HTR-PM project demonstrated it had reached “initial full power”.
Yes, that’s up to last month. PBMR’s are now officially real and online, at 105 MWe. The gap to thermal is a matter of thermodynamics and as the video discusses, we can use heat as heat most efficiently.
A broader look:
More on molten salt reactors:
And on reactor history and issues:
The point is, we have serious options outside the gamut that is commonly headlined. Which is itself a part of the story. More on that, later. END