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When a hazardous aerosol or gas is inadvertently or deliberately released in an occupied facility, the airborne material presents a hazard to people. Inadvertent accidents and exposures continue to occur in Los Alamos and other nuclear facilities despite state-of-art engineering and administrative controls, and heightened diligence. Despite the obvious need in occupational settings and for homeland defense, the body of research in hazardous aerosol dispersion and control in large, complex, ventilated enclosures is extremely limited.The science governing generation, transport, inhalation, and detection of airborne hazards is lacking and must be developed to where it can be used by engineers or safety professionals in the prediction of worker exposure, in the prevention of accidents, or in the mitigation of terrorist actions.In this study, a commercial computational fluid dynamics (CFD) code, CFX5.4, and experiments were used to assess flow field characteristics, and to investigate aerosol release and transport in a large, ventilated workroom in a facility at Savannah River Site. Steady state CFD results illustrating a complex, ventilation-induced, flow field with vortices, velocity gradients, and quiet zones are presented, as are timedependent CFD and experimental aerosol dispersion results. The comparison of response times between CFD and experimental results was favorable.It is believed that future applications of CFD and experiments can have a favorable impact on the design of ventilation (HVAC) systems and worker safety with consideration to facility costs. Ultimately, statistical methods will be used in conjunction with CFD calculations to determine the optimal number and location of detectors, as well as optimal egress routes in event of a release.

No abstract

High-efficiency particulate air (HEPA) filters have been subjected to simulated accident conditions to detetmine their response to abnormal operating events. Both domestic and European standard and high-capacity filters have been evaluated to determine their response to simulated fire, explosion, and tornado conditions. The htPA filter strl,:ural limitatior~s for tornado md explosive loadings are discussed. In addition, filtration efficiencies during these accident conditions are~eported for the first time. Our data indicate efficiencies between BO% and 90% for shock loadings below the structural limit level. He describe two types of testing for ineffective filtration-clean filters exposed to pulse-entrained aerosol and dirty filters exposed to tornado and shock pulses. Efficiency and material loss data are described. Also, the response of standard HEPA filters to simulated fire conditions is presented. We describe a unique method of measuring accumulated cxnnbustionproducts on the filter. Mditionally, data relating to pressure drop vs accumulated mass during plugging are reported for simulated combustion aerosols. The effects of concentration md moisture levels on filter Dluaaina were evaluated. Ue are obtainina all of the above data so that mathe-rnat{~al"modelscan be developed for fire,"explosion, canputer codes. These canputer codes cm be used to air cleaning systems to accident conditions. .

No abstract