R. Heck et al., HYDROGEN REDUCTION FOLLOWING SEVERE ACCIDENTS USING THE DUAL RECOMBINER-IGNITER CONCEPT, Nuclear Engineering and Design, 157(3), 1995, pp. 311-319
This paper summarizes the technical basis for using an integrated reco
mbiner-igniter system, called the dual concept for combustible gas con
trol during severe accidents in non-inerted pressurized water reactor
containments. The recombiners use catalytic coatings to turn molecular
hydrogen and oxygen gases into water vapor. They are self-starting an
d self-feeding, even under cold and wet conditions, and without any po
wer supply. It has been demonstrated by testing that the efficiency of
the catalytic coating of the recombiner is resistant to impurities ex
pected to be present in the containment atmosphere following a severe
accident. Catalytic and spark igniters have been developed for use in
controlled hydrogen ignition without an external power supply. Both ty
pes of igniters are capable of reliable ignition close to the upper an
d lower flammability limits. Based on experiments in realistic multi-c
ompartment test facilities which investigate the combustion and recomb
ination behavior in different accident situations, an efficient arrang
ement of the devices inside the containment is recommended to cover al
l possible scenarios. The dual concept causes only low loads which mai
ntain the integrity of the containment.