DIAL's Research Highlights
Diagnostic Instrumentation & Analysis Laboratory
Support of Closure Sites
Fernald Silos Project Monitoring and Control Integration
Waste stabilization formulation development.
Formulation testing continued. During February, the primary goal of the grout testing was to complete the low and high waste loading grout formulations. Samples were prepared at waste loadings between 6 and 14 percent to complete the low waste loading tests. Samples were prepared at waste loadings between 36 and 43 percent to complete the high waste loading tests. The initial testing of high waste loading grout formulations showed that the grout product becomes more sensitive to measurement, as well as random variation in the mix. Duplicate samples were prepared with differing results at waste loadings between 40 and 43 percent.
The following activities are planned for the upcoming months:
Accelerating Phytoremediation by Monitoring Plant Status
During the month of February, we have been analyzing samples and data from experiments finished in the last calendar year. We have also been preparing and revising manuscripts for publication.
Bio-availability and Speciation of Mercury in the Oak Ridge Ecosystem
We presented our study entitled "Bio availability and Speciation of Mercury in Soils from Oak Ridge, TN" at the Waste Management Symposium 2005, Tucson, Arizona. We also continued to analyze both soil and plant tissues from last fall's experiment.
In March, we will continue our design of the test bed and analytical efforts for the experiments from last fall. We will make a small scale test bed and start to prepare preliminary incubation experiments.
Support of Hanford Single Shell Tank Waste Disposition
In-tank/At-tank Characterization for Closure of Hanford Tanks
Stereovision. During February, the stereovision effort initiated a new software development effort for analysis of the stereovision images. This new effort utilizes a new approach from that previously used and is UNIX-based rather than Windows-based. The purpose of this effort is to reduce the required computational time. Our efforts to obtain volume estimations from 3-D reconstructions of test objects continued.
Laser-induced fluorescence-spectral imaging. During February, the LIF-SI effort recorded our first LIF spectra utilizing 532-nm excitation from a Nd:YAG laser and fiber optic pickup. We are currently analyzing the spectra. After replicating our results in March, we will utilize 355-nm Nd:YAG laser irradiation in order to determine which excitation wavelength is better.
Microwave-induced plasma-cavity ringdown spectroscopy. A blue diode laser has been applied to the detection of NO2 at 409 nm under atmospheric conditions. A sample gas with a concentration of NO2 of 250 parts-per-million by volume (ppmv) was diluted by argon to different concentrations and injected into a ringdown cavity for measurement. The measured spectra show good repeatability. Based on the known absorption cross-section of NO2 at ~ 409 nm, the detection sensitivity of the current system for NO2 is estimated to be approximately one part-per-billion by volume (ppbv). This work demonstrates that a portable NO2 ringdown spectrometer may be constructed.
Fiber optic sensors. In order to detect short-pulse optical emission signals from the scintillation fiber, a fiber-compatible, fast-response photo detection device is needed. This month, we located a fast-response, fiber-compatible UV/Vis spectrometer. The spectrometer, commercialized by Ocean Optics, Inc., uses an electronic shutter, and has a time resolution of 10 microseconds. A quote for this product was obtained and we intend to purchase this spectrometer in March.
Fourier transform profilometry. Fabrication of the prototype probe support tower module has been completed. Integration of the telescoping probe and the support tower will follow. For the elbow section housing the FTPs optics, our efforts to reduce the elbow weight continued. Weight reduction is necessary since there is a limit (500 lbs) on the weight that can be deployed above the tank and also a limit on the achievable bending moment of the elbow section (250 ft-lbs). Options currently under consideration are: 1) dual use of lamps for projection of the grid pattern and for utility illumination; and 2) replacement of the HID lamp with multiple high-intensity LEDs. Software development for FTP probe motion control also continued. Simulated images were acquired using the current version of the FTP probe elbow section; analysis of the images will follow. Limiting cases of possible target measurements that may be encountered in a Hanford tank have been presented. More measurement scenarios will be simulated.
Process Chemistry and Operations Planning for Hanford Waste Alternatives
Modeling calculations for the 2003 FIU unsaturated salt cake dissolution experiment were completed. Two different flow sheets for the dissolution of the S-112 simulant were used. The first was aimed at dissolution of the salt in the column followed by the mixing of the resulting dissolved salt stream with the interstitial brine. The calculated concentration profile for nitrate anion was represented by an initial increase (solids dissolution) followed by a decay (dilution). This profile was inconsistent with the experimental results from FIU and a second flowsheet was developed to account for the unusual concentration profiles observed. In the case of nitrate anion the experimental concentrations initially remained constant followed by a strong decrease to day 15 and then an increase. The revised flowsheet modified the distribution of the diluent to interaction with both the solid and interstitial fluid. The resulting water partitioning function made possible the determination of when channeling was occurring within the porous media and when the addition of water to the solids present dominated. Ionic profiles for all species with the exception of phosphate were in good agreement with the calculations. Experimental phosphate loadings were seen to increase at a faster rate than the model predictions signifying the possibility of solids segregation within the column.
Work on a manuscript describing the experimental determination of solubility for the Na-F-SO4-OH system continued. Additional fits using the regression package within the ESP software were performed and the draft paper was submitted to the Journal of Chemical and Engineering Data. Preparation of additional manuscripts describing the various solubility studies are in progress.
Extensive modeling calculations of the 2003 FIU unsaturated salt cake dissolution experiment was performed. Initial efforts centered on the preparation of the salt cake and the subsequent evaluation of the model predictions compared to the experimental results. With regard to the experimental results large decreases followed by increases were found for nitrate and sodium concentrations as a function of dilution. These trends combined with a decrease in the density of the fractions collected from 1.4 to 1.2 g/cc thereafter increasing to 1.3 g/cc as dilution proceeded are indicative of channeling within the salt matrix. Options for effective modeling of channeling are under consideration.
Data for the solubilities of Al, OH, Na, NO2, and NO3 are being collected for porting into a neural network. Data from the literature and ESP model simulations will be used. Discussions with engineers at Hanford continue with regard to access to the neural network software.
All of the 25°C and 50°C series of Al/PO4 have been filtered. Analysis is ongoing of the solids and filtrates. All of the solubility studies for the aluminum-nitrate system have also been completed. Analysis of the samples is in progress in the DIAL analytical laboratories.
Flexible Scintillating Optical Fiber Sensor for Determination of Liquid Level
Monitoring the response of quantum dot doped materials requires appropriate high speed optics for detecting emission photons. During this reporting period, a fiber optic compatible spectrometer with rapid photodetectors capabilities was priced through Ocean Optics. The spectrometer utilizes an electronic shutter with a time resolution of ten microseconds. This device should be able to more accurately detect the short-pulse optical emission signals from the scintillation fiber. Once purchased, the new spectrometer will be used to test the response of the quantum dot doped materials.
Disposition of Idaho HLW Calcine
Support of INEEL Calcine Disposition Project
Dr. Tom Thomas, Mike Patterson and Walt Tisdale from ICP-SP3 visited DIAL in January to review the operation and results achieved. The review was positive, and suggestions were made concerning the notebook keeping and organization. Hydroceramic samples formed to include 10% silica were judged promising for the compression test. Larger batches with different waste loadings were prepared. Some promising FeP waste forms, also containing silica, were mixed with non-calcine and had a glass-like structure. However, the addition of calcine significantly delayed the setting time.
Analysis of a large grout sample containing 25% dry waste loading and Na2S showed that the waste form passed the compression, TCLP, and PCT tests. Compositional analysis is in progress and MCC-1 will be performed. Batches with higher waste loading have been mixed. Experimentation with different formulations to achieve a higher total waste loading is in progress. The large hydroceramic test runs passed the compression tests. TCLP and PCT will be performed. Some problems with cracking and formation of crystals were observed when the material was cured in a sealed container. Materials cured at lower humidity did not show this problem. Some problems with setting time were experienced with the FeP. It appears that mixing and curing at 80°C, as suggested by Dr. Thomas, produces a waste form that can pass the compression test. More work is in progress.
Support of SRS Salt Disposition and Other SRS Alternatives
Support for SRS Salt Disposition Alternatives
Experiments designed to mimic cancrinite and/or hydroxysodalite formation at ambient temperature are approaching equilibrium. Preliminary results from the first set of experiments were inconclusive. We are currently awaiting results from XRD analysis of a sample from the layer formed in the 37H DASR experiment. Modeling of the 37H SRS simulant DASR experiment continues and results will be presented at the SRS Salt Technical Exchange meeting in March.
On-line Analysis for Defense Waste Processing Facility
Testing of the sludge sampling system continued. We found that the venturi attached in the sampling system in horizontal position gave less problem during the slurry circulation. Therefore, we have performed the study of the effects of experimental parameters (laser energy, gate delay and width) on slurry measurement by aligning the venturi in this position. Two venturis with different inner diameters (1/2 in. and 1 in., respectively) were also tested. The one with 1-in. inner diameter gives more reproducible flow which is needed to produce stable pulse-to-pulse LIBS signal. However, we encountered a problem with the Echelle spectrometer later in the month. The water tube connector on the spectrometer was broken. According to the manufacturer, it is very difficult to exchange without a new adjustment of the camera position. So the manufacturer will send an engineer to replace the water tube. Meanwhile, we are setting up another LIBS system so we can continue LIBS slurry studies.
Support of Production of High Waste Loading Glasses in the DWPF
Video camera observations are continuing for melting glass from the 155% and 185% slurries and powders. Various runs have been made starting with slurry and powder at room temperature and recording all event up to 1150°C (10°C/minute heating rate). Other experiments are in progress looking at the melting of newly added powder on top of molten glass at 850°C.
An outline for the paper to be presented at the American Ceramic Society in April has been prepared and discussed with Dave Peeler at SRS.
HEPA Filter Performance Assurance
Regenerable HEPA Filter Performance Testing
During February, Mott sintered metal fiber filters and Mott powdered metal fiber filters were challenged with RIC waste surrogate. Testing was performed at standard operating conditions for the test stand and particle generator. Two grades of the powdered metal filters were tested (0.5 mesh and 2.0 mesh). These filters were loaded and washed three times each. The powdered metal filters have a high differential pressure and load very slowly. One Mott sintered metal fiber filter was loaded and wash three times also. Scanning electron microscope (SEM) images were done for each of the filters tested. Future testing includes testing an additional two of each of the filters.
Inquiries may be addressed to:Dr. John Plodinec, Director
205 Research Blvd.
Starkville, MS 39762-5932