Researchers build up an idea of a hybrid thorium reactor

Russian researchers have proposed an idea of a thorium hybrid reactor that acquires extra neutrons utilizing high-temperature plasma held in a long magnetic trap. This project was applied in close collaboration between Tomsk Polytechnic University, All-Russian Scientific Research Institute Of Technical Physics (VNIITF), and Budker Institute of Nuclear Physics of SB RAS. The proposed thorium hybrid reactor is recognized from the present nuclear reactors by moderate power, relatively compact size, high operational security, and a low level of radioactive waste.

“At the initial stage, we get relatively cold plasma using special plasma guns. We retain the amount by deuterium gas injection. The injected neutral beams with particle energy of 100 keV into this plasma generate the high-energy deuterium and tritium ions and maintain the required temperature. Colliding with each other, deuterium and tritium ions are combined into a helium nucleus so high-energy neutrons are released. These neutrons can freely pass through the walls of the vacuum chamber, where the plasma is held by a magnetic field, and entering the area with nuclear fuel. After slowing down, they support the fission of heavy nuclei, which serves as the main source of energy released in the hybrid reactor, ” says professor Andrei Arzhannikov, a chief researcher of Budker Institute of Nuclear Physics of SB RAS.

The main advantage of a hybrid nuclear fusion reactor is the simultaneous utilization of the fission response of heavy nuclei and the synthesis of light ones. It minimizes the inconveniences of applying these nuclear responses separately.

Additionally, this kind of reactor has lower necessities for plasma quality and makes it conceivable to supplant up to 95 percent of fissile uranium with thorium, which guarantees the impossibility of an uncontrollable nuclear reaction. Also, hybrid reactors are moderately compact, have high power, and produce a small amount of radioactive waste.

“The hybrid reactor consists of two elements. The main part is the energy-generating blanket as the active zone of a nuclear reactor. It distributes nuclear fissile material that is part of nuclear fuel. Due to this, a fission chain reaction of heavy nuclei is possible. The second part is placed inside the blanket to generate neutrons that fall into the energy-generating blanket. The thermonuclear fusion reactions are generated inside this part filled with deterium plasma, releasing the neutrons. A feature of the hybrid reactor is that the operating blanket, where the fission reactions take place, is in the subcritical state (near-critical). Operating at a constant power level, a conventional reactor is in a critical condition, supported by a control and safety system, ” says Igor Shamanin, the head of the TPU Division of Natural Sciences and the TPU Isotope Analysis and Technology Laboratory.

As indicated by Dr. Shamanin, the blanket depended on an idea of a multi-reason high-temperature gas-cooled low-power reactor fueled by thorium. This idea was created at Tomsk Polytechnic University and now it is broadly represented in different scientific publications.

Right now, the project members are thinking about the option to build up an experimental stand dependent on the TPU reactor, which will comprise of a thorium fuel assembly and a neutron source.

The consequences of ongoing investigations on this project are published in the journal Plasma and Fusion Research.