Fault Tree Analysis of System Anomaly Leading to Red Oil Explosion in Plutonium Evaporator

Abstract

Results of scenario identification, preparation of reliability data, fault tree construction and its analysis, are rendered for a system anomaly considered liable to lead to a red oil explosion in a Pu evaporator of a typical model of reprocessing facility. Japan Atomic Energy Research Institute has introduced the model plant data, the basic failure frequency data together with the fault tree analysis code FTL from NUKEM GmbH, Germany, and used to execute the above analyses.'The frequency of occurrence of the system anomaly initiated by failures of the Pu purification process such as a pulse column failure or a mixer settler failure has been evaluated to be 2 . 6~l O -~/ y r for the solvent carry over into the evaporator for the German model reprocessing facility. In addition to this event, if an abnormal state such a s continuously heating the solution to over 150°C inside the evaporator would happen with the analyzed occurrence probability of 1 . 0~1 0 -~, it would be the more possible to result in the red oil explosion. The occurrence frequency for the combined events has been calculated to be 2.6 x 10-"/yr, so small compared with the public acceptance limit which might be set as 1 x lO-O/yr.

Investigation of an Explosion at a Styrene Plant with Alkylation Reactor Feed Furnace

“…The heating furnace (F101) exploded and the fuel continued to enter and accumulate in the furnace. Then, the fuel and air formed a mixed flammable substance (here, concentration was already within the boundaries of the explosion) that was exposed to the furnace surface caused by high temperature flashover (with enough energy) [18,19]. Factors of the heating furnace explosion by FTA are as shown in Table 3.…”