TRISO
TRISO (from English TRistructural-ISOtropic ) is a processing form of nuclear fuel that consists of triple-jacketed Pac-beads . In the center is a core of uranium (IV) oxide , or a uranium / thorium - oxide , with an internal layer of isotropic pyrolytic graphite , a layer of high-strength silicon carbide isotropic and an outer layer of pyrolytic graphite is coated. The core of the German variant has a diameter of 0.5 µm, the entire particle is 0.92 µm in size.
An additional inner carbon layer is porous and provides expansion volume for the absorption of fission products; the two pyrographite layers ensure gas tightness.
TRISO was around 1970 in the UK for the Dragon - high temperature reactor development (1967-1975), the inventor applies DT Livey. In Germany it was used in the AVR (Jülich) from 1981 , but not in the THTR-300 . The TRISO particles are clearly superior to the older, double-coated BISO particles in terms of particle breakage caused by radiation . On the other hand, the effect of TRISO silicon carbide as a diffusion barrier for some nuclides such as cesium-137 and silver-110m is unsatisfactory at higher temperatures - also in comparison with BISO particles. For this reason, only maximum working temperatures of 750 ° C are currently envisaged for high-temperature reactors with TRISO fuel, and the planned use of TRISO fuel for high-temperature process heat generation (950-1000 ° C) has been postponed.
Further development is currently only taking place in the USA. In tests there, a short-term temperature resistance of the coatings of 1800 ° C was achieved.
Individual evidence
- ↑ Michael J. Kania, Heinz Nabielek, Karl Author: German TRISO Fuel Performance Envelope and Limits
- ^ Adams Engines: Concepts and Design Principles , Section Fuel Element Construction
- ^ MST Price: The Dragon Project origins, achievements and legacies . In: Nuclear Engineering and Design . tape 251 , January 1, 2012, doi : 10.1016 / j.nucengdes.2011.12.024 .
- ↑ Karl Verfondern, Heinz Nabielek, Michael J. Kania, Hans-Josef Allelein: High-Quality thorium TRISO Fuel Performance in HTGRs , In: Writings of the Research Center Jülich. Energy & Environment series, p. Iv
- ^ Moormann, R .: A safety re-evaluation of the AVR pebble bed reactor operation and its consequences for future HTR concepts. In: Reports from Forschungszentrum Jülich. No. 4275, June 2008, pp. 1–37 http://juser.fz-juelich.de/record/1304/files/Juel_4275_Moormann.pdf
- ↑ a b Idaho National Laboratory : Next-generation nuclear fuel withstands high-temperature accident conditions ( Memento of the original from July 14, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , September 25, 2013
