Small-Scale Spray Releases: Additional Aerosol Test Results (original) (raw)
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Large-Scale Spray Releases: Initial Aerosol Test Results
2012
One of the events postulated in the hazard analysis at the Waste Treatment and Immobilization Plant (WTP) and other U.S. Department of Energy (DOE) nuclear facilities is a breach in process piping that produces aerosols with droplet sizes in the respirable range. The current approach for predicting the size and concentration of aerosols produced in a spray leak involves extrapolating from correlations reported in the literature. These correlations are based on results obtained from small engineered spray nozzles using pure liquids with Newtonian fluid behavior. The narrow ranges of physical properties on which the correlations are based do not cover the wide range of slurries and viscous materials that will be processed in the WTP and across processing facilities in the DOE complex.
Large-Scale Spray Releases: Additional Aerosol Test Results
2013
The success criteria for achieving the large-scale aerosol test objectives are discussed in Table S.2. These test criteria were established in Test Plan TP-WTPSP-031, Rev. 1.0. Table S.2. Success Criteria for Large-Scale Aerosol Tests Success Criteria How Testing Did or Did Not Meet Success Criteria Criterion for Test Objectives 10 Measure the concentration and size distribution of known aqueous suspensions with the Malvern used for aerosol measurements and quantitatively compare the Malvern (Insitec-S) results with the known values to estimate the Malvern (Insitec-S) accuracy for measuring aerosols. Met: The concentration and size distribution of eight powder systems was measured and compared to known values based on material balance or list/reference properties. The eight powders included mono-and poly-disperse glass bead powders and irregular non-spherical powders. Tests with these powders evaluated concentration and size distribution accuracy under different instrument configurations (i.e., lenses and spacer bars) relevant to Phase I and Phase II testing. Furthermore, tests evaluated the accuracy of corrections made when analyzing aerosols distributed over ~400 and ~900 mm path lengths. Criteria for Test Objectives 12 and 13 Measure the droplet size distribution, total volume concentration of droplets, and total volume flow rate sprayed for each of the breaches and simulants tested. Met: Up to three Malvern Insitec-S aerosol analyzers were used to continuously measure the droplet volume concentration and size distribution during spray leak testing in the large-scale test chamber for all orifice and pressure combinations. The total volumetric flow rate of spray generated through each orifice was determined by monitoring differential loss of simulant mass from the simulant feed and storage tanks as a function of time during active spray. For in-spray measurements, measure the droplet size distribution for each of the breaches and simulants tested. Met: Three Malvern-Insitec-S aerosol analyzers were used to measure the "in-spray" size distribution of water and clay simulant sprays for all test pressure and orifice combinations. In-spray measurements involved placing the aerosol analyzers in the direct path of the spray (before it impinged on the wall downstream of the spray header and engineered breach) such that the spray passed directly through the measuring volume of the Malvern Insitec-S. This contrasts with the normal "in-chamber" aerosol configuration where the analyzers are positioned above the spray and outside of its direct path. Characterize the viscosity or rheology, PSD, bulk density, and surface tension of each simulant tested. Met: Phase II tests evaluated water and two concentrations of mixed dry clay powders (composed of 80 wt% kaolin and 20 wt% bentonite) slurried water. For these three simulants, the rheology, PSD, bulk density, and surface tension where characterized through direct measurement or through use of standard chemical references (for common properties such as the viscosity of water).
2013
The Waste Treatment and Immobilization Plant (WTP) at Hanford is being designed and built to pretreat and vitrify waste currently stored in underground tanks at Hanford. One of the postulated events in the hazard analysis for the WTP is a breach in process piping that produces a pressurized spray with small droplets that can be transported into ventilation systems. Literature correlations are currently used for estimating the generation rate and size distribution of aerosol droplets in postulated releases. These correlations, however, are based on results obtained from small engineered nozzles using Newtonian liquids that do not contain slurry particles and thus do not represent the fluids and breaches in the WTP. A test program was developed to measure the generation rate, and the release fraction which is the ratio of generation rate to spray flow rate, of droplets suspended in a test chamber and droplet size distribution from prototypic sprays. A novel test method was developed t...
Advances in Research, 2016
Pharmaceutical aerosol is a pressurized system that depends on the power of a compressed or liquefied gas to expel the contents from the container. Therapeutic performance of pharmaceutical aerosols is affected by various factors such as actuator tube design, orifice diameter, concentration of surfactant in the system, moisture content and deposition of emitted dose, vapor pressure of propellants, spray pattern, efficiency of valve crimping and measurement of particle size aerosols. Unique feature of this dosage form is the presence of propellants, whose properties like flash point, viscosity and density and presence of active ingredients, containers, valves and actuators also modify the aerosol performance. A pharmaceutical aerosol must satisfy certain standards to claim it to be a quality drug. The main standard for the quality of any drug is the intrinsic and extrinsic elements which contribute directly or indirectly to the safety, potency, efficacy, stability, patient
Release mitigation spray safety systems for chemical demilitarization applications
2010
Sandia National Laboratories has conducted proof-of-concept experiments demonstrating effective knockdown and neutralization of aerosolized CBW simulants using charged DF-200 decontaminant sprays. DF-200 is an aqueous decontaminant, developed by Sandia National Laboratories, and procured and fielded by the US Military. Of significance is the potential application of this fundamental technology to numerous applications including mitigation and neutralization of releases arising during chemical demilitarization operations. A release mitigation spray safety system will remove airborne contaminants from an accidental release during operations, to protect personnel and limit contamination. Sandia National Laboratories recently (November, 2008) secured funding from the US Army's Program Manager for Non-Stockpile Chemical Materials Agency (PMNSCMA) to investigate use of mitigation spray systems for chemical demilitarization applications. For non-stockpile processes, mitigation spray systems co-located with the current Explosive Destruction System (EDS) will provide security both as an operational protective measure and in the event of an accidental release. Additionally, "tented" mitigation spray systems for native or foreign remediation and recovery operations will contain accidental releases arising from removal of underground, unstable CBW munitions. A mitigation spray system for highly controlled stockpile operations will provide defense from accidental spills or leaks during routine procedures.
2013
To date, majority of the work done on measuring aerosol releases from failure of process piping was done using simple Newtonian fluids and small engineered-nozzles that do not accurately represent the fluids and breaches postulated during accident analysis at the Hanford Waste Treatment and Immobilization Plant (WTP). In addition, the majority of the work conducted in this area relies on in-spray measurements that neglect the effect of splatter and do not yield any information regarding aerosol generation rates from this additional mechanism. In order to estimate aerosol generation rates as well as reduce the uncertainties in estimating the aerosol release fractions over a broad range of breaches, fluid properties and operating conditions encountered at the WTP, the Pacific Northwest National Laboratory (PNNL) has designed, commissioned, and tested two experimental test stands. The first test stand, referred to as the large-scale test stand, was designed specifically to measure aero...
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Effectiveness of water sprays in mitigating toxic releases
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Water spray curtains are often advertised as means to mitigate the consequences of released chemicals from high pressure tanks. Spray curtain effectiveness claims by certain vendors are misleading—a curtain placed at the periphery of a tank will only scrub a puff of a release. A spray curtain that can effectively contain a consequential release will look very different and cost much more. Studies that demonstrate spray curtains to be effective assume low gas velocities. However, calculations show that pressurized liquid NH3 or HF when released from an orifice to the atmosphere comes out at a high velocity and momentum in the form of a two‐phase jet. The jet must travel quite a distance before the velocity drops enough to be effectively scrubbed by a water curtain. The water curtain therefore needs to be at this large distance and consequently the diameter of the water curtain manifold ring needs to be quite large to be effective. This paper presents engineering calculations to estim...
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