title: Experimental determination of the minimum onset temperature of runaway reaction from a radioactive salt disposal in asphalt.
abstract: In order to clarify the reason for the most hazardous explosion in the history of the Japanese nuclear power development by a radioactive salt disposal in asphalt, an adiabatic process was developed using a Dewar vessel to minimize the temperature difference between the reactants and the surroundings. By this means, the heat evolution from a reaction which is readily lost can be detected at a lower temperature imitating the accidental condition. A series of ambient temperature-tracking Dewar experiments on asphalt salt mixtures were conducted under different initial ambient temperatures, such as 230, 210, 190, and 170 degrees C, respectively. As a result, it was observed that from 190 degrees C the sample's temperature rose until a runaway reaction occurred. The minimum onset temperature for the runaway reaction of the asphalt salt mixture was determined to be 190 degrees C, which is close to the initial temperature of approximately 180 degrees C, the same temperature as the real accident. This implies that at near this operational temperature, initial faint chemical reactions may occur and lead to further rapid reactions if heat is accumulated at this stage.
authors.affiliation: National Research Institute of Fire and Disaster, 14-1 Nakahara 3-chome, Mitaka-shi, Tokyo 181-8633, Japan. li@fri.go.jp
authors.forename: Xin-Rui
authors.initials: XR
authors.lastname: Li
authors.forename: Jin-Hua
authors.initials: JH
authors.lastname: Sun
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Koseki
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Hasegawa
mesh_terms: D005107:Explosions; D006838:Hydrocarbons / Q000737:chemistry*; D011210:Power Plants; D011850:Radioactive Waste; D012492:Salts / Q000737:chemistry; D013696:Temperature
chemical_list: D006838:Hydrocarbons; D011850:Radioactive Waste; D012492:Salts; C006647:asphalt