Design of Catalytic Recombiners for Effective and Safe Hydrogen Removal fromContainments of Pressurized Water Reactors

摘要

In case of a severe accident in pressurised or boiling water reactors a high amount of hydrogen up to about 20,000 mn 3rnmight be generated and released into the containments. The mixture consisting of hydrogen and oxygen may either burn orrndetonate, if ignited. In case of detonation the generated shock wave may endanger the components of the plant or the plantrnitself. Consequently, effective removal of hydrogen is required. The fact that hydrogen and oxygen react exothermally onrncatalytically acting surfaces already at low temperatures generating steam and heat is made use of in catalytic recombiners.rnThey consist of substrates coated with catalyst (mainly Platinum or Palladium) which are arranged inside a casing. Beingrnpassively acting measures, recombiners do not need any additional energy supply.rnTo study the recombination processes in detail three REKO test facilities are available at ISR. The experimental programrnincludes investigations of single substrates like flat plates or meshes and a complete recombiner section. The results yieldrnknowledge on reaction kinetics and serve as basis for designing recombiners with respect to the heat transfer conditions andrnheat management. The experimental results show that the reaction is controlled by mass transfer.