Abstract: A process for precluding or reducing the danger to a system or its surroundings by mixtures comprising reactive substances which react chemically and/or physically and the release of pollutants during an accident, in particular by the combustion of hydrogen in the containment of a nuclear power plant and/or by the release of fission products therefrom, wherein at least one portion of said reactive substances and/or pollutants are kept separately during system malfunction or are at least partially separated into two areas and kept separately there, or wherein a potentially dangerous reaction is stopped in a first, especially hazardous area by transferring at least one portion of at least one of said reactive substances into a second area.