Study on the effect of simulated nuclear industry working conditions on the explosion severity parameters of zirconium powder and the explosion mechanism

Abstract

Explosion caused by zirconium powder was revealed as one of main reasons in accidents happened in reprocessing of spent fuel in nuclear industry. It is urgent to study the explosion severity characteristic of zirconium dust cloud due to the great harm of its explosion. According to the equipment used in the actual post-treatment process in nuclear industry, the 20L cylindrical explosion equipment as a scale model was manufactured as the experimental device. The experimental results showed that Pmax and (dp/dt)max increased at first and then decreased with the increase of concentration. Small zirconium particles produced larger value of explosion severity parameters. Interestingly, initial temperature had no significant effect on Pmax of zirconium powder. However, the value of (dp/dt)max was strongly dependent on the initial temperature. Additionally, the oxidation degree of zirconium dust and temperature generated during explosion were studied by means of oxygen content and crystal form of explosion products. The study found that the particles develop toward spheroidization and its size became smaller, indicating that zirconium particles combustion is a heterogeneous shrinking core process. Under the condition of constant mass, increased number of ZrO2 particles leads to enlarged particle total surface area, increasing the amount of radioactive material released.