DIAL's Research Highlights

Characterization of Heavy Metals, Radionuclides and Organics in Heterogeneous Media

Sensitive detection of toxic chlorinated compounds. Efforts to obtain cavity ringdown spectra for chlorinated dioxin species were initiated during June. Like non-chlorinated dioxin, the spectrum is quite broad and scans over several laser dyes will be required to complete the characterization of the observed transition. As expected, the spectrum is red-shifted with respect to absorption features of non-chlorinated dibenzo-p-dioxin. These are the first ringdown spectra ever obtained for a chlorinated dioxin species, representing another important step toward the development of monitors for dioxin.Vasudev, PI

Volatile organic compound monitoring using diode lasers. Chlorobenzene was detected using diode laser cavity ringdown at levels below the measurement limit of our vacuum gauges. Thus, a gas handling system will be construction to allow the expansion of a high concentration of gas in a small volume into the larger volume of the measurement cell. The volume ratio of the two cells will be used to calculate the concentration of analyte in the measurement cell. Winstead, PI

Isotopically selective monitors for transuranic elements. Laser induced fluorescence efforts utilizing europium as a surrogate for uranium continued during June, with efforts directly primarily toward optimizing the flow stability of the ICP atomization source. In cavity ringdown efforts, an isotopically resolved spectrum for mercury was obtained. The measured isotopic abundances are in excellent agreement with established values. Monts, PI

Laser-induced breakdown spectroscopy system as a process monitor and control for waste thermal treatment. Efforts to improve the LIBS calibration for solid samples continued. In particular, the effect of varying the distance between the focusing lens and sample surface was investigated. The preliminary data demonstrate that a shorter lens to surface distance (LTSD) provides significantly better LIBS sensitivity and precision. More data will be collected to determine the optimum LTSD for solid calibration. Singh, PI

Environmental Control Device Testing

Performance enhancement of the ionizing wet scrubber. We are scheduled to have the particulate system installed in two months; to accomplish this, we must first complete training at the WES site. ArunKumar, PI

Testing of a ceramic regenerative heat storage device for dioxin control and heat recovery. Fabrication is underway. Nearly all required materials have been ordered, but several items have not yet been received. This delay will put the project slightly behind schedule. Norton, PI

Transportable calibration test stand for diagnostic instrumentation. LIBS measurements on preheated air were continued this month. Combustion work will begin in July. ArunKumar, PI

Evaluation and performance enhancement of a submerged bed scrubber. Engineering drawings have been completed, and a supplier for custom made, large diameter acrylic tubes has been located. ArunKumar/Plodinec, PIs

Waste Treatment and D&D Support: Process Monitoring and Control

Dioxin and PCB studies. The majority of materials needed for fabrication of the test stand have been received; however, piping for the inner flight tube was damaged and must be replaced. Several modifications of the original design have been made over the past month, and fabrication of the unit will begin as soon as the damaged tubing is replaced.

One of the major uncertainties of design has involved the development of a small scale particle feeder capable of delivering ash into the inner flight tube with a minimal volume of nitrogen gas as a carrier, thus reducing the temperature drop at the point of particle addition. A prototype has been developed and will be evaluated and refined during the month of July.

Work has continued in selection of data from the literature to be used in formulation of the artificial intelligence software. It is expected that this part of the overall effort will continue for another two months. Waggoner, PI

On-line multi-spectral imaging of thermal treatment process. Delivery of the ultraviolet acousto-optical tunable filter (UV AOTF) was expected in late June, but has not yet been received; after a testout period in the laboratory, we will begin a series of experiments using the DIAL combustion test stand to simulate field conditions. During June, we made good progress on spectral analysis of cotton leaves for signatures relating to crop health; this work is expected to provide us with preliminary results for a remote monitoring work to be prepared this fall, in addition to preliminary results for grant proposals for other funding sources. Monts/Su, PIs

Detection and possible mitigation strategy for gall layer in Hanford high-level waste melters. Data collected with the initial test bed indicate feasibility of determining the presence of a gall layer of approximately 7 mm. Measurements of bubble diameter and bubble height on the surface prior to bursting have been made both with and without the presence of a methanol layer. Finally, the rates of movement of bubbles through the honey and methanol layers was determined and the velocities of surface waves for both phases were calculated. A new test bed has been developed that more accurately reflects conditions present in a melter. Work is proceeding with this test bed and the honey-methanol surrogates to more accurately determine the minimal thickness of gall layer that can be detected and the time line for data collection and interpretation. Ramsey, PI

Imaging instrumentation application and development. Thermal imaging: work continued on the software modification for the adjustable surface emissivity values.

Profilometry: software development for the synchronization between camera triggering and Xe strobe light was completed. The prototype of system imaging acquisition software has been completed. This allows the user to acquire an image as the Xe strobe light is at peak intensity. Work also continued on system training for the researcher in the newly installed software development platform.Jang, PI

Saltcake dissolution. Solubility studies for the Na₃FSO₄ system continued. Equilibrium concentrations were set based on the ESP predictions. Nominally, the sulfate and fluoride molalities were at 10% above the calculated SLE curve. Solutions were allowed to equilibrate at room temperature for a period of two weeks with gentle shaking followed by filtration. Few solids were observed indicating that the initial solution conditions were at, or slightly below, the SLE response. Solutions were then remade at 20% above the ESP predictions and are currently equilibrating. The results indicate that ESP under predicts Na₃FSO₄ solubility.

Simulations examining the impact on database selection continued for tank BY-102. Use of the Trona database for representation of carbonate behavior and of the Na₂SNaCl database for representation of the sulfate behavior has led to improved predictions for not only the sulfate anion in the liquid supernate phase, but also has impacted the predictions for other species such as nitrate and chloride. For these anions (nitrate and chloride), the ESP predictions using only the Trona and Public databases agreed well with experimental measurements of Herting at dilution levels greater than 100%, but were approximately twice as large as the experimental measurements at a 50% dilution level. Failure to include the special database for sodium sulfate (anhydrous) and sodium sulfate decahydrate when conducting simulations on dissolution of BY-102 saltcake leads to ionic strength predictions that are elevated since the sulfate cannot be partitioned into the solid phase. This elevated ionic strength then impacts predictions of the solid/liquid partitioning of other anions, giving rise to discrepancies such as those noted for nitrate and chloride. This behavior is different than that noted when the need for the specialized carbonate database was identified late in FY 99.

ESP calculations for the sodium fluoride sulfate double salt will be revised to examine the use of the Gibbs free energy of formation for the pure species and for the double salt. ESP predictions for the solubility envelope in water indicate significant deviation from the literature experimental data with ESP predicting a lower solubility. Lindner, PI

Feed stability and chemistry. Interfacing of the thermocouples and pressure transducers of the salt well pumping test loop with the data acquisition system was completed. Calibration runs with water indicated equal pressure drops from the regularly spaced transducers. Experiments using the modified SX-104 surrogate composition have begun and plug formation was observed. In one case, the plug formed downstream of the fourth heat exchanger (with water only routed to that shell); in the other, a plug formed between heat exchangers three and four when cooling was applied only at exchanger three. Observation of the plug indicated that the material was a gel consisting of sodium dodecahydrate. The data consisting of the pressure drops and temperatures are being analyzed and dilution experiments are in progress.

Model development continued. A number of simulations were run where a plug was formed. This condition represents the extreme case that is undesirable in practice. The calculations have been noted as taking some time. A new workstation was ordered and should arrive by the middle of July. Lindner, PI

Diagnostic Field Applications Coordination and Testing Support

Glenn Bastiaans and Tom Thomas from TFA visited on June 19. We discussed a number of possible areas of interest making use of DIALs capabilities and the high priority site needs associated with characterization and monitoring. The possible contributions that the DFACTS program could make were emphasized. Cook, PI