Comparison of calculations with the BUSCA code against the LACE-Espana aerosol decontamination experiments
The decontamination of a flow containing aerosols and soluble vapours when it passes through a water pool is often very efficient. This is an important consideration in nuclear reactor safety analysis: in the event of a severe loss-of-coolant accident, quantities of water could remain in the coolant system between the core, releasing radioactive vapours and aerosols, and the breach to the containment or auxiliary building (e.g. in the pressurizer or steam generator secondary side). Mechanistic computer codes such as BUSCA, Ramsdale et al (1993), have been developed to predict decontamination in water pools by modelling the formation of bubbles, bubble behaviour and the thermal hydraulics and aerosol physics inside bubbles. The experimental programme LACE-Espana, Marcos et al (1994), generated data on aerosol decontamination in a water pool. A steam-nitrogen mixture loaded with caesium iodide particles was injected into a part-filled tank 2.5m below the water surface. The gas injection rate and the aerosol distribution were varied over eleven tests. The work presented here concerns the interpretation of the LACE-Espana tests using the BUSCA code. It is seen that despite taking into account aerosol losses in the apparatus before the pool, the calculations generally underpredict, often significantly, the experimentally observed decontamination. This result is in qualitative agreement with an earlier study, Calvo and Alonso (1994), though significantly different input data were used in those calculations and higher decontamination was predicted. The calculation-experiment difference is explained in part by the approximation of treating the aerosol entering the pool as lognormal, a limitation of the code. Looking for other explanations, the modelling of jet impaction deposition is examined since this is by far the dominant decontamination mechanism in the calculations.
- OSTI ID:
- 166516
- Report Number(s):
- CONF-9510126--
- Country of Publication:
- United States
- Language:
- English
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