Factors affecting the microstructure of pyrolytic carbon coatings on nuclear fuel particles
- eds.
Chemical vapour deposition played an important part in development of fuel for HTR. The fuel is coated particles dispersed in a graphite matrix. The multilayer coating contains the fission products; the preferred coating materials are pyrolytic carbon and silicon carbide. A charge of particles is fluidised in a heated graphite chamber by a flow of gas. The geometries of the chamber and the injector(s) are chosen to produce a generally spouting mode of fluidisation. A hydrocarbon is introduced as part of the fluidising gas and a reaction zone temperature in the range 1200-2000$sup 0$C is used. The hydrocarbon decomposes and the eventual products are carbon and hydrogen. Recirculation of the particles leads to deposition of pyrolytic carbon on the particles. The thermal contribution by the fluidising gas mixture is always negative. Differences in the behaviour of pyrolytic carbon under fast neutron irradiation have been observed, and some coatings derived from methane appear to have insufficient ductility in service. A series of studies was carried out on model fluidised beds, leading to the development of a radioactive particle tracer technique. New experiments designed to study microstructure control in pyrocarbon coatings are reported. Systematic variations of particle density, particle diameter, nature of the hydrocarbon and fluidising gas composition were made and these are related to the resultant microstructures. (DLC)
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-33-015362
- OSTI ID:
- 4100657
- Country of Publication:
- United States
- Language:
- English
Similar Records
Increase in pyrolytic carbon optical anisotropy and density during processing of coated particle fuel due to heat treatment
Crystalline structure of pyrocarbon film deposited on pyrolytic boron nitride. Interim technical report
Related Subjects
*HTGR TYPE REACTORS-- COATED FUEL PARTICLES
*PYROLYTIC CARBON-- CHEMICAL VAPOR DEPOSITION
360601* --Materials--Other Materials--Preparation & Manufacture
FLUIDIZED BED
MICROSTRUCTURE
N50320* --Metals
Ceramics
& Other Materials--Plastics & Other Materials--Preparation & Fabrication
TRACER TECHNIQUES