Apparatus for treating an exhaust gas from nuclear plant

Claim 1

In an apparatus for treating exhaust gases which include a radioactive gas, said apparatus comprising cryogenic liquefaction and distillation means for liquefying and distilling the radioactive gas from the exhaust gases, radioactive gas recovering means, conduit means for conveying exhaust gases to be treated to the inlet means of said cryogenic liquefying and distilling means from a source of gases to be treated and for conveying treated gases from an outlet means thereof to the recovery means, the improvement wherein said cryogenic liquefaction and distillation means comprises a plurality of distillation units which are disposed within a casing that is divided into a plurality of chambers which respectively enclose each unit of the cryogenic distillation means and which provide an airtight seal around the cryogenic distillation means, a vacuum compartment disposed between each of said chambers so as to increase the thermal insulation effect between the chambers, and a heat insulating material having adsorbent properties packed into said chambers and surrounding the distillation units, said adsorbent material being a particulate material selected from the group of active carbon, silica gel, synthesized zeolite and activated alumina, said particulate adsorbent having a specific surface area greater than 100 m 2 /g and being capable of adsorbing the radioactive gas in the event that there is any leakage of the radioactive gas from the cryogenic distillation means during the recovery operation thereby to prevent accidental escape of the radioactive gas upon occurrence of the leakage.