Large-Scale Spray Releases: Additional Aerosol Test Results

Abstract

One of the events postulated in the hazard analysis for 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 event involves extrapolating from correlations reported in the literature. These correlations are based on results obtained from small engineered spray nozzles using pure liquids that behave as a Newtonian fluid. 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 in processing facilities across the DOE complex.To expand the data set upon which the WTP accident and safety analyses were based, an aerosol spray leak testing program was conducted by Pacific Northwest National Laboratory (PNNL). PNNL's test program addressed two key technical areas to improve the WTP methodology (Larson and Allen 2010). The first technical area was to quantify the role of slurry particles in small breaches where slurry particles may plug the hole and prevent high-pressure sprays. The results from an effort to address this first technical area can be found in Mahoney et al. (2012). The second technical area was to determine aerosol droplet size distribution and total droplet volume from prototypic breaches and fluids, including sprays from larger breaches and sprays of slurries for which literature data are mostly absent. To address the second technical area, the testing program collected aerosol generation data at two scales, commonly referred to as small-scale and large-scale testing. The small-scale testing and resultant data are described in Mahoney et al. (2013), and the large-scale testing and resultant data are presented in Schonewill et al. (2012). In tests at both scales, simulants were used to mimic the relevant physical properties projected for actual WTP process streams.Examination of the results from the initial (subsequently referred to as Phase I) aerosol spray leak testing described in the preceding paragraph highlighted some uncertainties in evaluating aerosol generation that remained after the original scope of work was completed. Specifically, there was uncertainty with respect to aerosol behavior (namely aerosol release fraction and generation rates) for:  simulant(s) near the WTP rheological boundaries of (6 Pa/6 mPa·s and 30 Pa/30 mPa·s)  simulant(s) with solids loadings greater than 20 wt%  simulant(s) with a small solids fraction of particles that have a relatively high density  lower spray pressures (i.e., specifically 100 and 200 psig in the small-scale tests)  in-spray measurements.The need for additional (subsequently referred to as Phase II) aerosol spray leak testing was identified. The purpose of the study described in this report is to provide experimental data and analyses to supplement the results obtained during P...

Hydrogen Gas Retention and Release from WTP Vessels: Summary of Preliminary Studies

“…A wide range of Bingham rheological parameters can be obtained by varying the total clay fraction in water and this simulant is an initial choice for non-hazardous, non-Newtonian slurry simulants for gas retention and release testing. The 80:20 K:B simulant has been used in a variety of PJM studies (e.g., Bamberger et al 2005;Russell et al 2005) and spray-release studies (e.g., Schonewill et al 2013;Daniel et al 2013). Based on previous simulant development studies (e.g., Poloski et al 2004), EPK kaolin (pulverized grade, Edgar Minerals, Inc.) and Big Horn bentonite (CH-200 powdered grade, WYO-BEN, Inc.) are the preliminary selection for materials for blending with Richland city water for the non-Newtonian clay slurries.…”

Small-Scale Spray Releases: Additional Aerosol Test Results

“…As the list indicates, the testing and analysis in the Phase II small-scale study was primarily concerned with measuring sprays with simulants that were not used in Phase I. The companion study describing the Phase II large-scale testing, which also includes examinations of spray and chamber geometry, is available in Daniel et al (2013). Table S.1 provides a summary of each small-scale aerosol test objective for the Phase II testing, whether the objective was met, and a discussion of the test results.…”

“…Other objectives identified in Test Plan TP-WTPSP-031, Rev. 1.0 apply to either the Phase I test program, discussed in Mahoney et al (2012), Mahoney et al (2013), and Schonewill et al (2012), respectively, or the Phase II large-scale aerosol testing presented in Daniel et al (2013). Met?…”

“…All configurations were tested, as well as some column dispersion tests, using a series of mono-and poly-disperse suspensions. The testing and results are summarized in Section 6.6 of this report and described extensively in Section 6 of Daniel et al (2013).…”

“…Because the large-scale performed a series of successful in-spray measurements in Phase II (see Daniel et al 2013), additional effort was not undertaken to obtain better small-scale in-spray data during the Phase II study.…”