Toxic gas discharged from nuclear or chemical plant - is enclosed in rigid plastics foam mixed as gas is released

摘要

An apparatus for enclosing in a rigid plastics foam a toxic gas released from a gas vessel in an accident consists of a release point, typically a bursting disc, which discharges the released gas into a main conducting it to a manifold; from the manifold a number of branches, each containing a bursting foil, lead into tanks containing the various components for forming the multi-component foam. A further branch from the manifold leads via a venturi nozzle into a gas buffer tank; the component tanks have bursting foils which respond (burst) before a corresponding bursting foil at the outlet from the buffer tank. Discharge pipes leading from the component tanks contain constrictions and lead to a plastics mixing chamber; the discharge pipe from the buffer tank also leads, via a venturi nozzle, to the mixing chamber. Thus the first emission of gas expels the plastics components from the tanks into the mixing chamber, followed shortly afterwards by the main flow of gas from the buffer tank; this gas thus acts as expanding agent, expelling the mixed plastics foam from the chamber via several outlets, each initially closed by a bursting foil. For a discharge from a reactor vessel or from a chemical vessel containing toxic gases, when the pressure rises in the vessel above a permissible level. The arrangement is esp. suitable for a discharge where a fire occurs in a reactor containment structure, resulting in polluting of the filters, blockages and the need to discharge the gas to atmosphere. This arrangement enables the gas to be imprisoned in rigid plastics foam and thus not discharged to atmosphere.