[en] The vaporizer in extinguishing of Large Equipment Dismantling Facility (LEDF) that cost is considering as a plan to cut down as part of a rationalization design highly. When the vaporizer is deleted, it becomes here where liquefied carbon dioxide is emitted in the direct cell, it is necessary to grasp the action and extinguishing performance of the pressure change in the cell by rapid evaporation test of the emitted liquefied carbon dioxide. So pressure action inside the fire laboratory in liquefied carbon dioxide release and a putting out the fire tests due to the combustion time of the combustible were enforced by using the general fire laboratory with Demonstration Test on Extinguishing of the cell (I) in the 11th year of Heisei. However, since these tests are afire laboratory without airtightness, it needs to grasp the pressure action at the time of liquefied carbon dioxide discharge under the airtight high conditions of having assumed the still more nearly actual cell. The cell (II) Demonstration Test on Extinguishing using the vessel of Sodium Leak Fire and Aerosol test rig (SOLFA-2) container inside of OEC was carried out. The results were as follows. (1) In order to grasp the pressure action of the vessel, the internal pressure of SOLFA - 2 was set as - 50mmH₂O, and emitted liquefied carbon dioxide. Consequently, the tendency for the pressure in the vessel to descend rapidly immediately after liquefied carbon dioxide discharge, and to descend gently-sloping through the process which goes up gradually after that and goes abruptly up for a short time was seen. (2) The process which goes abruptly up in an above-mentioned short time is considered to be the factors with main what some liquefied carbon dioxide emitted in the vessel changed to dry ice, and was deposited taken and sublimating surrounding heat, and evaporating again. (3) It sets to total flooding system and the average minimum temperature in the vessel becomes about - 48degC, and at local applications system becomes about - 60degC. (4) It found out that negative pressure was maintainable by considering as the conditions which carry out negative pressure maintenance of the pressure in the vessel, and setting up the amount of liquefied carbon dioxide discharge to about 85% to the exhaust flux of the air in the vessel. (5) In order to have controlled the rapid rise of the pressure in the vessel, it turns out that it is effective to emit liquefied carbon dioxide slowly. (author)