Particle and Aerosol Tracking

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Particle and Aerosol Tracking


Discussion

Control Room
GOTHIC™ is an industry trusted tool for providing engineering solutions for a variety of applications, including fission product tracking, dry aerosol transport and ventilation assessments. A distinctive feature of GOTHIC is the ability to track many different fields/substances in a simulation. Conservation equations are solved for three (or more) primary fields, including continuous liquid, steam, N non-condensing gases, and any number of M interacting dispersed droplet/aerosol fields. Optional secondary fields are also available to represent ice, mist/fog as well as any number of X solid particle components, Y dissolved gases and Z tracers (including decay and formation of daughter products) that can be tracked in the vapor, liquid and drop fields. A drop/aerosol field in GOTHIC can represent solid particles and/or water, allowing for the simulation of dry aerosols such as dust or other particulates.

The dispersed drop/aerosols are based on aerosol mechanics, including consideration of the size distribution, agglomeration, formation (or entrainment) and deposition. For each drop/aerosol field, conservation equations for mass, energy, momentum, interfacial area and number density are solved. This allows each field to move with its own velocity, momentum and temperature. The drop/aerosol inventory for each field in each computational volume or cell evolves during a simulation based on the transport, phase change and interactions with other drop/aerosol fields and with surfaces. The number concentration and size distribution are computed separately for each field, thus allowing aerosols with a wide range of sizes to be tracked in a single application. In addition to the solid particle capability, another distinctive feature of GOTHIC is the ability to track user defined tracer elements (including radioactive decay and daughtering of nuclides) in the liquid, vapor and droplet fields as well as surfaces and filters. This capability allows GOTHIC to model fission product transport and release or the removal of particulates or harmful toxins from exhaust gases using a spray scrubber or some other type of filtration system. GOTHIC includes component models for fans, filters, charcoal filters, dryers/demisters, etc. The aerosols and other filtered material is removed or accumulated in these components.
General Filter
Charcoal Filter
Dryer/Demister

Recent enhancements to the software provide options to transfer tracers between phases with condensation or evaporation, convert from one tracer to another on radioactive decay and tracer transport by molecular and turbulent diffusion. This has application for tracking tritium or other materials that can change phase. The tracers can also be used to track concentration of iodine species and other chemicals (including [H+] and [OH-] for pH analysis).

The above capabilities are particularly applicable to facilities that handle radioactive material such as laboratories and medical isotope facilities. Zachry Nuclear is currently developing a GOTHIC model of a medical isotope facility including the irradiation unit, hot cells and glove boxes, and the facility ventilation including dampers, filters, forced flow to maintain pressure differential and hydraulic connections between areas and to the environment. The model can be used to evaluate normal operations as well as the consequences of an accident. Additional applicable capabilities in GOTHIC include reactivity coefficients and point kinetics.

Analysis Support

For more information on particle and aerosol tracking please contact Anita Gates or Steve Winter. The Analysis Division contact list is here, including phone numbers.