December 2004

DIAL's Research Highlights

Diagnostic Instrumentation & Analysis Laboratory
Mississippi State University
John Plodinec, Principal Investigator

Prepared for the U.S. Department of Energy
Office of Science and Technology
Cooperative Agreement DE-FC01-04EW54600

Task 1

Support of Closure Sites

Fernald Silos Project Monitoring and Control Integration

Waste stabilization formulation development.

Formulation testing continued. During December, the primary goal of the grout testing was to determine if high waste loading grout formulations pass the waste acceptance criteria. Samples were prepared at waste loadings between 32 and 43 percent. 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. Repeatability in the results has become an issue with the higher waste loading formulations. These tests will continue as part of the work scope for 2005. The final grout stabilization report was prepared and submitted to Fernald management.

Dr. Charles Waggoner and Brian Kauffman met with various management personnel at the Fernald Site to discuss the scopes of work outlined for 2005. Representatives from DOE, the Silos 1 and 2 Project, Operations, and the Technical Issues Team attended the meeting and provided input to the work scope and identified priority issues.

The following activities are planned for the upcoming months:

• continue formulation testing with K-65;
• continue to perform high waste loading grout testing;
• perform low waste loading grout testing;
• perform TCLP on baseline grout samples;
• finalize Jacobs Engineering computer model and perform water balance simulations.

Accelerating Phytoremediation by Monitoring Plant Status

During the month of December, we finished the phytoremediation experiment of mercury with brake fern; the experiment was started in October. Plant and soil samples have been collected and will be analyzed in the coming months.

Bio-availability and Speciation of Mercury in the Oak Ridge Ecosystem

We have finished the laboratory analyses of soil/water/plant samples from the following studies: (1) pilot scale experiments, which study the bio-availability of different mercury species (such as nitrate, chloride and sulfide) in soil at low, intermediate and high levels; (2) solution/liquid phase speciation of mercury from different sources in spiked soil without plants and also after a growing season with brake fern plants; (3) redistribution and transformationof mercury in solid phase components of soils spiked with various mercury sources; and (4) the effects of plants and incubation time on bio-availability and chemical stability.

We gave three presentations as part of the Mercury Workshop at Oak Ridge National Laboratory in November. We are now summarizing these results.

In January, we will continue our efforts in summarizing the previous results and write a number of manuscripts. We will start to seek information on designing and building the test bed.

Task 2

Support of Hanford Single Shell Tank Waste Disposition

In-tank/At-tank Characterization for Closure of Hanford Tanks

Stereovision. During December, the stereovision effort investigated the effect of image rectification upon the precision of stereovision volumetric determination. These investigations are part of our on-going efforts to optimize the stereovision system for conditions appropriate to the Hanford waste tanks.

Laser-induced fluorescence-spectral imaging. During this month, the LIF-SI effort continued working on optimizing experimental conditions for recording LIF spectra. Utilizing new software provided by the manufacturer, a problem with triggering the detector in gate mode was overcome.

Microwave-induced plasma-cavity ringdown spectroscopy. Efforts this month focused on characterization of the new blue external cavity diode laser and on the construction of a short open-path ringdown cavity to be combined with a microwave plasma source for uranium isotopic measurements. A draft of a manuscript entitled "Atmospheric Ringdown Measurements of Elemental Mercury Directly from Mercury Contaminated Water and Soils" was prepared; the results reported in this paper were obtained in support of Task 1.3 (bio-availability and Speciation of Mercury in the Oak Ridge Ecosystem).

Fiber optic sensors. During this month, we received the CdSe/ZnS core-shell quantum dots that we purchased. Preliminary tests have been conducted to dope the quantum dots into polymers, such as PDMS and PMMA. The quantum dot-doped polymers have a yellow color and emit bright yellowish fluorescence when excited with a mercury lamp. Further work will focus on spectroscopic analysis of the emission spectrum and identification of the species which produces the fluorescence signal.

Fourier transform profilometry. Design of the probe support tower

continued. The optical layout of the FTP imaging elbow section has been finalized. Development of the modular mechanical assembly will follow. Images of the simulated target images have been acquired using the final FTP probe's elbow section prototype. Analysis of the images will follow.

Process Chemistry and Operations Planning for Hanford Waste Alternatives

Additional experiments were directed towards working up the equilibration samples from the aluminum - phosphate and aluminum - nitrate experiments. To date, all but one of the series for the aluminum phosphate systems have been filtered and have been submitted for analysis. Eight solubility series were performed for the aluminum - nitrate; of these, four have been completed, and the remainder are being filtered and diluted.

Considerable effort was devoted toward modeling the FIU tall column experiment completed in 2003. For this experiment, four batches of salt cake were prepared at different extents of evaporation, thereby resulting in a chemically inhomogeneous simulant distribution along the column. Results from model preparation of the batches compared favorably with the results provided by FIU. Problems were, however, encountered during the dilution phase of the experiment. Here, a large number of unit operations were required to describe the process. Process model size limitations were exceeded requiring the porting of portions of the simulation to additional process models. This work is being reviewed with the goal of simplifying the calculations.

Studies have commenced on developing solubility relationships that can be used within a neural network such that limitations of the ESP program can be eliminated. Workers at CH2MHill are interested in better predictions of solid-liquid equilibria using their existing H2 model. The existing partitioning is based on wash and leach factors. Simply calling the ESP program at various phases of an H2 simulation has been deemed impractical owing to the amount of time required by the thermodynamic equilibrium model and data transfers from ESP to H2. The goal for this work is to develop the neural network model such that additional accuracy within H2 can be attained as well as offering the ability for tracking difficult systems such as phosphate. Available solubility data taken from our previous studies as well as literature data will be used.

Flexible Scintillating Optical Fiber Sensor for Determination of Liquid Level

The CdSe/ZnS core-shell quantum dots to be used for doping of various materials, including sol-gel, were received during this reporting period. Although the major effort to produce the doped materials will commence at the beginning of the 2005 calendar year, preliminary attempts were made during this period. The polymers poly(dimethylsiloxane) and poly(methyl methacrylate) were each separately embedded with the core-shell quantum dots. The resulting materials were yellow in color and emitted a bright yellow fluorescence when exposed to ultraviolet light.

Efforts will continue toward optimizing the procedure for doping polymeric materials with quantum dots. In addition, spectroscopic analysis of the emission spectrum will be conducted.

Task 3

Disposition of Idaho HLW Calcine

Support of INEEL Calcine Disposition Project

Progress in this area will be reported next month.

Task 4

Support of SRS Salt Disposition and Other SRS Alternatives

Support for SRS Salt Disposition Alternatives

Analytical results from the 37H drain, add, sit and remove experiment fractions have been received and modeling of the experiment is nearing completion. The remaining solids formed from the 37H DASR experiment consisted primarily of the layer formed from the simulant. The layer was observed to have a thick, paste-like consistency and was allowed to dry. Upon drying, the solid was rock-like and needed to be ground thoroughly. After grinding, the texture of the solid was similar to talc. Preliminary results on the solids from ICP and TIC identify the primary solid to contain aluminum and silicon with a molar ratio of 1:1 and the secondary solid to be Na₂CO₃·1H₂O. Submission of solids from the layer sample for XRD is underway.

After obtaining XRD, TGA and EDX analysis of a solids portion from each of the cancrinite/sodalite experiments prepared at 25°C, it was determined further analysis is needed in order to correctly identify these solids.

On-line Analysis for Defense Waste Processing Facility

The initial test of the sludge sampling system, which was designed for the slurry measurement, was completed. The test results show that the sampling probe needs some minor modifications to ensure reproducible alignments among tests. The probe modification design has been completed and given to the machine shop for fabrication. We will continue testing the modified sampling system with the RIC slurry before receiving DWPF simulant from SRS. Work on the glass measurement continued. LIBS data with glass samples of different lithium concentration levels were recorded. These data are being studying to investigate the effect of self- absorption of the Li line on the accuracy of Li concentration measurements as well as proper analytical techniques for these types of data.

Support of Production of High Waste Loading Glasses in the DWPF

Some initial slumping experiments have been completed. Slurries from both the 155% and 185% were melted at 1150°C for one hour. Then a thin layer of slurry was poured onto the top of the molten glass and the crucible returned to the furnace for short periods of time. After two minutes, there was still a crust with the 155%, but the 185% had been totally melted into the original glass.

In another experiment, crucibles of each heated to 1150°C were taken out of the furnace, and then more slurry poured on the surface; then they were allowed to cool on the bench top. The "crust" remaining on top was different for the two slurries. The 155% "crust" seems softer. Differential scanning calorimetry (DSC) of the two crusts indicates that more of the water was driven off the 185% more quickly than the 155%. The only real difference in the thermogram was a lack of a water peak for the 185% "crust."

We have now set up a video camera to observe the melting process from room temperature (slurry) to 1150°C. Results are expected during the next reporting period.

Task 5

HEPA Filter Performance Assurance

Regenerable HEPA Filter Performance Testing

During the month of December, both Porvair and Ceramem regenerable filters were loaded with RIC surrogate and washed between loadings. This sequence was performed three times with each filter. Also, additional Porvair filters were loaded only once with RIC surrogate. These filters were all imaged by the scanning electron microscope on campus at Mississippi State.

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