HTGR Knowledge Base

Conference Article: Graphite corrosion under severe HTR accident conditions

Katscher, W.; Moormann, R. (Kernforschungsanlage Juelich G.m.b.H. (Germany, F.R.))

Abstract

In connection with analyses of severe, mainly hypothetical air and water ingress accidents in High Temperature Gas-Cooled Reactors (HTR), the paper deals with the kinetics of the reactions between matrix respectively structural graphite materials for the German HTR projects and oxygen, carbon dioxide and water vapour. With helium as carrier gas, the experiments presented were carried out in the in-pore diffusion controlled regime taking into consideration the burn-off dependence of the reaction rate: the results are given for maximum rates valid for that graphite burn-off field in which the reaction rate no longer increases with burn-off. In the case of the water gas reaction, reaction rates are given as a function of pressure up to 55 bar. As an example for the accident analyses mentioned above the benign behaviour of a pebble bed reactor core with respect to temperature development, migration of reaction zones, burn-off distribution etc. is demonstrated for hypothetical air ingress into the primary circuit of a medium size HTR.

view the full text of this article (7 pages, format: PDF, size= 498kB)

key words: air; chemical reaction kinetics; corrosion; graphite; htgr type reactors; oxidation; oxygen; pebble bed reactors; pressure dependence; reactor accidents; water; accidents; carbon; chemical reactions; gas cooled reactors; graphite moderated reactors; homogeneous reactors; reaction kinetics; solid homogeneous reactors
Reference:
Specialists' meeting on graphite component structural design, JAERI Tokai (Japan), September 8-11, 1986
International Atomic Energy Agency, Vienna (Austria). International Working Group on Gas-Cooled Reactors
IWGGCR--11, pp:182-188