Thermal modeling of the Tomsk-7 accident
- Los Alamos National Lab., NM (United States)
The April 1993 accident at the Tomsk-7 facility in Russia renewed concerns about the safety of the Purex process under upset conditions where concentrated nitric acid comes into contact with tributyl phosphate and a hydrocarbon diluent. This paper describes a numerical model used to analyzed the thermalhydraulic behavior of the tank at Tomsk from the time of nitric acid addition to vessel rupture. The purposes in developing the model were to establish a reasonable set of conditions that would lead to the accident, and to investigate conditions that would necessarily have prevented the accident. The basis used for the calculations is a simplified system consisting of five regions: a reaction zone bounded by acid and aqueous layers below and an organic layer and free volume vented to atmosphere above. This system results in nine ordinary differential equations: three energy equations, three continuity equations, and three equations to track the growth of the reaction zone. These equations model four types of runaway behavior; the Tomsk accident was classified as a delayed runaway. Many combinations of parameters produced calculated delayed runaway behavior for Tomsk, with the primary variations in the results being the time to runaway and the maximum pressure. Scenarios identified which would have prevented the accident were increasing the vent area, stirring the tank, and reducing the amount of reactive carbon.
- OSTI ID:
- 210290
- Report Number(s):
- CONF-9509139--
- Country of Publication:
- United States
- Language:
- English
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