July 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. The formulation testing continued. Some baseline formulations were developed using cement, fly ash, slag, and Advacast. However, the Fernald Closure Project process group indicated that a supplier of blended cement and slag could not be found in the greater Cincinnati area. The consequence is that only two dry stabilization agents can be used in the grout formulations, given that there are only two dry storage silos available in the processing facility. Therefore, only cement and fly ash are to be used for the grout formulation development work.

Wastewater equilibration study. The wastewater equilibration study (WES) continued through July. Four additional treatment samples were prepared with K-65 solids to water ratios of 1:5. The samples were agitated for seven days in order to bring the suspended and dissolved species into equilibrium. Following the seven-day agitation, two of the samples were allowed to settle for approximately 48 hours, and the remaining two samples were allowed to settle for approximately two weeks. These four WES samples will ultimately be filtered through a 0.45-micron filter and buffered with calcium hydroxide to varying pH levels, ranging from a pH of 10.5 to a pH 11.5. Radium-226 levels will be measured before and after the samples are buffered.

The following activities are planned for the upcoming months:

• Continue formulation testing with K-65.
• Complete the wastewater equilibration study.
• Participate in the full-scale surrogate testing of the silos processing facility.
• Begin settling tests using K-65 in order to determine the density of the settled solids as well as percent solids remaining in the supernatant.

Accelerating Phytoremediation by Monitoring Plant Status

During the month of July, we finished a mercury phytoremediation experiment with brake fern. The experiment was started in May. Mercury was provided as HgCl₂, HgS and Hg(NO₃)₂. Plants and soil samples from different treatment groups were collected for chemical analysis. We will continue to analyze samples and data for the coming months.

Task 2

Support of Hanford Single Shell Tank Waste Disposition

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

Stereovision. Efforts to optimize the stereovision system for operation in the Hanford tanks continued as did our effort to prepare a scientific journal paper describing our state-of-the-art system. We have also begun addressing calibration protocol procedures.

Laser-induced fluorescence-spectral imaging. During May, the charge-coupled device (CCD) camera detector on the spectrometer was diagnosed as malfunctioning, was sent to the manufacturer for repair, and was received back from the manufacturer in late May. Subsequent testing in June revealed that the CCD detector was still not functioning properly and in late June it was once again been shipped to the manufacturer for repair. During July, the manufacturer repaired the system and at the end of July shipped the system back to us. During early August, we will test the system and begin setup of experiments to collect laser-induced fluorescence spectra of selected simple uranium and thorium compounds. We have also contacted Hanford in order to arrange for a conference phone call to discuss the progress of the Task 2.2 efforts and also discuss plans for the next Cooperative Agreement year.

Microwave-induced plasma-cavity ringdown spectroscopy. Microwave-induced plasma-cavity ringdown spectroscopy (MIP-CRDS) effort this month focused on successful implementation of the newly developed, tube-shaped MIP as a plasma source for Hg detection under atmospheric conditions. Multiple tube-shapes and orientations were evaluated to determine the best plasma configuration for enhanced system stability. Preliminary results indicate enhanced detection sensitivities. Implementation of this new tube-shaped plasma source will require further optimization of the experimental conditions. Additional efforts this month included upgrading the flow control system to accurately measure/control the gas flow rates to the plasma.

Fiber optic sensors. An optical fiber has been connected to a photomultiplier tube (PMT) using a laboratory-designed connector. The dark current of the PMT with and without the optical fiber connected was recorded and compared. A significant dark current was observed when an optical fiber is coupled to the PMT. These efforts are essential for optimizing the response of the fiber optic sensor system.

Fourier transform profilometry. During July, the Fourier transform Profilometry (FTP) effort completed the design and fabrication of two needed plates to center the FTP probe. Work continued with the design of the probe insertion/retraction tower and of the probe elbow. We gathered information on components (camera, projector, and lamp) that are to be mounted in the probe elbow section. A prototype system for cable management of electrical cables has been established. The prototype consists of two double-pulleys and will be utilized to work out the details of cable management. Cable management system drawings have been finished. Pulleys and materials for cable management system have been ordered and some of materials have been received. Design of the keying of the telescoping sections has also been completed. The key and slot arrangement utilizes a slot cut into the outer (and intermediate) tubes and a pin attached to the intermediate (and innermost) tubes to constrain relative rotational movement, yet allow extension of the telescoping tube sections. A set of straps will be attached to the outside of each slot to restore torsional rigidity that is lost when the slot is cut along the outside of the tube. Using the current FTP probe one-meter elbow optical setup, work continued with FTP measurements at simulated target distances of 15 ft and 27 ft. Improvement of the fringe pattern projection has been identified as a means to further improve FTP measurement results. Utilizing a better projector light diffuser to improve the fringe pattern projection is underway. We are also seeking other means of FTP system performance improvement.

Information sifting. The information sifting effort has completed implementing all the features for the spectral identification tool and is currently documenting the installation instructions for the tool.

Process Chemistry and Operations Planning for Hanford Waste Alternatives

All of the aluminum - phosphate and aluminum - nitrate solutions targeted for solubility studies have now been prepared and are equilibrating. Time dependent studies are continuing to determine the final equilibration periods. The aluminum concentrations observed during the equilibration period represent decays. Statistical error analyses have been performed to assess the potential experimental errors on the determined concentrations. In all cases these errors were less than 3%.

Additional modeling in support of the FIU tall column experiment continued. Upgrades were made to the regression fits for the double salt database (DBLSLTDB). Improved comparisons between baseline experimental data and with earlier salt cake dissolution simulations has been observed.

Tank Leak Detection and Monitoring System

Efforts this month were focused on the successful implementation of the newly developed, tube-shaped MIP as the plasma source for Hg detection under atmospheric conditions. Multiple tube-shapes and orientations were evaluated to determine the best plasma configuration for enhanced baseline stability. Preliminary results indicate enhanced detection sensitivities. Additional efforts this month included the design and fabrication of a new sample chamber. In preparation for the sample chamber, an updated flow control system has been ordered to accurately measure/control the gas flow rates to the plasma and the sample chamber. Implementation of this new apparatus will require further studies to optimize the experimental conditions to this configuration.

Task 4

Support of SRS Salt Disposition and Other SRS Alternatives

Support for SRS Salt Disposition Alternatives

A new batch of SRS tank 38H salt cake simulant was prepared and work a flow through experiment was conducted. Fractions collected during the experiment were analyzed and the ionic profiles are being compared to ESP predictions. Calculations of porosity and permeability are in progress following the determination of combined fraction viscosities.

Previous work on the drain, add, sit, and remove salt cake dissolution experiment (patterned after the SRS low curie salt process) revealed unusual concentration profiles for nitrite and aluminum. Typically nitrite anion will remain in the aqueous phase as the saturation point is generally greater than 10 m. In both DASR experi8ments the nitrite loading initially decreased as is typical of direct dilution and then increased followed by a final decrease. Preliminary reasons for this behavior included the precipitation of sodium nitrite within the simulant as the experiment was proceeding or mixing effects between any original interstitial brine with dissolved salt solution. Examination of the overall loading for nitrite revealed that the concentration of ~ 3 m was considerably less than the solid liquid equilibrium point. Consequently, a number of simulations were performed where the mixing of the interstitial liquor and the dissolved salt solution was controlled. Calculations were able to predict the concentration profiles for all species that were in better agreement with the experimental profiles than previous simulations assuming complete mixing. The extent of mixing is dictated by the amount of interstitial liquid remaining after the drain portion of the experiment and the profile of the interstitial liquid within the remaining salt cake. The results indicate that additional information, such as the extent of brine saturation within a tank, would be useful for providing more accurate anion and cation predictions during the dissolution process.

On-line Analysis for Defense Waste Processing Facility

During this reporting period, we started the initial study of the sludge samples obtained from DWPF. The problems encountered with the slurry sample were loss of focus due to splattering of target material, attenuation of emission signal due to splattering, and surface cavitations. Appropriate steps were taken to overcome these problems by periodically monitoring the focus of the beam, sending a stream of air over the bottle opening to clear the emission path of splattered particles, and rotating the sample to provide new surface for ablation, respectively. With these steps, we are able to record LIBS spectra from the slurry provided by SRTC. However, more work on sample handling is needed in order to obtain a reproducible LIBS signal from the slurry.

Task 5

HEPA Filter Performance Assurance

Regenerable HEPA Filter Performance Testing

During the month of July the HEPA project team finished the filter penetration tests and tested a variety of cleanable filters. These were ceramic filters with a membrane coating manufactured by CeraMem Corporation. These filters were challenged with potassium chloride (KCl) and ferric oxide (Fe₂O₃). The two sizes of cleanable filters tested were 3 x 3 (15 centimeters length) and 4 x 4 (1 inch length).

The 3 x 3 refers to three openings by three openings on the ends and likewise for the 4 x 4. The test plan for the 3 x 3 filters consisted of loading and washing alternately three times. This was done for two filters. One 3 x 3 filter was washed with a dilute acid solution of 0.016 M HNO3 and 0.012 M HCl with a pH of 1.64. The second 3 x 3 filter was washed with a concentrated acid solution of 10% HNO₃ with a pH of 0.14. Both of these filters were challenged with ferric oxide (Fe⁺³). Both these filters were cut and examined using the scanning electron microscope (SEM) on the campus of Mississippi State University.

The test plan for the 4 x 4 filters consisted of loading and washing once. DIAL tested four 4 x 4 filters. One filter was challenge with KCl, but not washed. This filter was cut and examined by the SEM. Another 4 x 4 filter was challenged with ferric oxide, but not washed. This filter was then cut and examined by the SEM. The final two 4 x 4 filters were loaded with ferric oxide and washed once. One 4 x 4 was washed with a dilute acid solution of 0.016 M HNO₃ and 0.012 M HCl with a pH of 1.64. The second 3 x 3 filter was washed with a concentrated acid solution of 10% HNO₃ with a pH of 0.14. These two filters were cut and examined by SEM also.

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