May 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
Instrumentation recommendations. In May, DIAL personnel participated in a follow-up workshop held at the Fernald site. The intent of the workshop was to discuss the recommendations, made by various groups, which would help minimize possible processing risks associated with the Silos Advanced Waste Retrieval (AWR) Project. DIAL completed the monitoring and instrumentation white paper. The paper identified all monitoring requirements and the instrumentation necessary to identify when pockets of silos material with higher than expected radiological activities are encountered during full-scale retrieval operations. The final paper also provided an evaluation of instruments that could potentially be used to accomplish the necessary monitoring by outlining the advantages, disadvantages, cost, and schedule impact of each. R. Arunkumar traveled to the Fernald site and presented the results of the white paper to the Silos Project Management Team.
Full-scale surrogate test. R. Arunkumar traveled to the Fernald site to assist in the performance of full-scale surrogate testing of the AWR system. The tests were performed to assess the processing difficulties of the full-scale system prior to processing radioactive material.
Waste stabilization formulation development. The K-65 material was removed from its secondary packaging and placed in the glove box unit. Approximately half of the 27 pounds of K-65 was homogenized and repackaged in individual 500-mL containers. The 500-mL containers were then overpacked in a metal 4-gallon can. The 500-mL containers of K-65 are removed from the can as needed in order to minimize the amount of raw material that is exposed to the glove box environment, in turn, minimizing the radon concentration within the glove boxes.
The formulation testing was initiated, beginning by analyzing three samples of K-65 to identify the average percent moisture of the material. Approximately twenty waste stabilization formulas were tested in May. The goal of the initial tests was to determine how the behavior of the grout mix changed when various treatment components were changed. This initial testing will be used to develop a baseline treatment formula for the K-65.
The initial grout formulations proved to be excessively stiff and did not meet the operating requirements of the full-scale remediation facility. Consequently, a second set of samples was prepared using a plasticizing agent in order to improve the workability of the grout mixtures. Advacast 500®, a plasticizing agent, improved the grout's mixing and flow properties without an increase in water content. However, the addition of Advacast® tended to increase the tendency of the grout mix to form a layer of bleed water after it was poured.
The following activities are planned for the upcoming months:
- Continue formulation testing with K-65,
- Begin the wastewater equilibration study,
- Perform real-time data analysis for the full-scale surrogate testing of the SWRS,
- Participate in the full-scale surrogate testing of the Silos processing facility.
Accelerating Phytoremediation by Monitoring Plant Status
We started a new mercury phytoremediation experiment with brake fern. Mercury was provided as HgCl2, HgS and Hg(NO3)2. We will collect plants and soil samples at different stages of the phytoremediation process. Spectral reflectance will be used to monitor the process. This experiment is expected to run through June and July. Meanwhile, we will continue to analyze samples and data from previous experiments.
Task 2
Support of Hanford Single Shell Tank Waste Disposition
In-tank/At-tank Characterization for Closure of Hanford Tanks
Stereovision. The graduate student who developed and programmed the software for our stereovision system left the project for an employment opportunity. A replacement graduate student programmer has been selected.
Laser-induced fluorescence-spectral imaging. The charge-coupled device (CCD) camera detector on the spectrometer was diagnosed as malfunctioning, was repaired by the manufacturer, and is now being tested to verify its operation. We will use this system to collect laser-induced fluorescence spectra of selected simple uranium compounds.
Microwave-induced plasma-cavity ringdown spectroscopy. Forbidden Hertzberg band I 
transitions of O2 pose a strong background spectral interference for the mercury transition line at 254 nm in atmospheric-pressure, microwave-induced plasmas (MIPs). Vigorous efforts this month were focused on reducing this background interference by optimizing plasma operating parameters, such as microwave power, gas flow rates, and plasma location. The estimated detection sensitivity of mercury currently is only ~ 250 parts-per-billion, based on the system with an optimized plasma power in the range of 100 - 150 W. This detection sensitivity is expected to be improved by further optimization of other parameters of the system. Once the mercury measurement is completed in this candle-shape MIP, the same laser source will be applied to a newly-developed tube-shape MIP source to pursue sensitivity-enhanced mercury measurements. Additionally, the preliminary testing of the new blue diode laser system was completed this month; the system is ready for uranium measurements.
Fiber optic sensors. Work during this month focused on connecting the Hamamatsu photomultiplier tube (PMT) to a computer and reading the PMT output signal with the computer. This work has been done and the data acquisition program that comes with the PMT has been verified to be functioning appropriately.
Fourier transform profilometry. The fabrication of a 4-in. riser mock-up of a Hanford waste tank has been completed. The mock-up will be utilized for FTP-probe fitting tests as well as the development of a tower to support the insertion probe. Engineering drawings for fitted pulleys inside the telescoping section of the insertion probe have been completed. A scheme of straps to bridge the key-way slot has been developed to solve a potential problem associated with the key-way slot of the telescoping insertion probe. Development efforts for the FTP optical components arrangement of the detachable elbow section of the insertion probe continued. Laying out all the components of the elbow section on a laboratory optical table has been completed. The effects of varying the position of the optical components on the results of FTP measurement will be determined; an optical rail system will be procured and assembled for this effort. Efforts to correct target distortions introduced by the non-perpendicular FTP orientation also continued; the tank's curvature produces the non-perpendicular orientation. Software coding for both surface height (Z) and X-Y correction has been completed. Applying these corrections to simulated target measurements has yielded results with restored target height and shape. With an improved restoration process, missing data ("black holes") in the non-perpendicular FTP images has been restored as well. Further experiments with variations in image contrast, projected fringe line frequencies and image resolution are ongoing to verify and eventually eliminate the target height step effect.
Information sifting. The user is now able to view any two spectra in the libraries as a graph and to zoom a user-selected portion of the spectra for a close-up view.
Process Chemistry and Operations Planning for Hanford Waste Alternatives
Solubility studies for a number of aluminum systems continued. Experiments are being performed at two temperatures, 25 and 50°C, as a function of aluminum loading. Three systems, aluminum-nitrate, aluminum-carbonate, and aluminum-phosphate are being evaluated. Initial evaluation of solubilities for the aluminum-nitrate system indicated a long-duration approach to equilibrium. Extrapolation of the available data to the ESP predictions revealed that up to 12 weeks may be required for equilibrium. Similar results were also found for the aluminum-phosphate system at 25°C. Work on the aluminum-carbonate system was begun with the thought of determining the conditions under which Dawsonite (NaAlCO3(OH)2) would form. After a period of three months Dawsonite crystals were not observed. Efforts were begun to find a convenient reaction such that seed material could be prepared.
Work on modeling the FIU pilot-scale salt cake dissolution experiments continued. Each of the four prepared batches was made at differing extents of evaporation. There was therefore a chemical distribution along the length of the column. Integration of the first three batches within ESP was possible; however, the fourth batch had a very low free water content resulting in numerous model conversion difficulties. Efforts to work around this problem are in progress. Additional calculations for support of the retrieval of the waste in Hanford tank S-102 are also in progress. Here, available core sample data was obtained and plotted as a function of tank height from the top of the waste level. The results indicate two layers with the top layer rich in nitrate and the bottom layer rich in phosphate. An attempt will be made to divide the tank waste into these two layers and then model the retrieval process with dissolved waste from the upper layer flowing into and mixing with the interstitial liquid in the smaller lower layer.
Flexible Scintillating Optical Fiber Sensor for Determination of Liquid Level
The general control code for the scintillating fiber optic sensor detection system was written during this reporting period. The detection component of the sensor (Hamamatsu HC135-11) includes a bialkali photomultiplier tube embedded with a micro-controller and therefore requires programming for operational control. The three subprograms written to date are briefly introduced here. Subprogram A sets a 1200-V differential between the photocathode and anode, effectively maximizing the detection sensitivity. Subprogram B is initiated to begin a reading sequence from the PMT digital output line. This output signal contains four bytes of data per light intensity reading. Finally, subprogram C is used to convert the incoming digital signal into a representative integer value. This program (combined subprograms) will be utilized during initial testing of the sensor and then expanded for final control of the scintillating fiber optic system. The previously prepared sol-gel coated capillaries will be tested using the programmed detection system.
Tank Leak Detection and Monitoring System
Due to the unavailability of the wedged ringdown mirrors, the non-wedged ringdown mirrors were aligned on a pair of mirror mounts which were installed on a portable optical plate. The system runs well with this alternative instrument configuration, and atmospheric moisture concentrations can be readily determined. The ringdown cavity, the optical plate, the laser source, the optical fiber/optics, the detector, the electronic control parts, and a laptop, all are loaded in a rubber cart, which is a portable, rugged, and stand alone unit with a single power plug to the exterior of the system. Currently, scanning of spectrum and the determination of moisture concentrations have to be performed manually. Once a software package is developed, which will be employed for the data processing and the diode laser wavelength scan, the system will perform automatically. Further developments include fabrication of a long subsurface leak probe which will be used for the simulated sample introduction.
Task 3
Disposition of Idaho HLW Calcine
Support of INEEL Calcine Disposition Project
Together with Dr. Tom Thomas and Mr. Walt Tisdale, we have finalized the test plan. The QAPP document is also being reviewed and a procedure manual is being prepared. We have initiated the procurement of the material and the necessary equipment.
Task 4
Support of SRS Salt Disposition and Other SRS Alternatives
Support for SRS Salt Disposition Alternatives
ESP modeling assistance was given on plutonium calculations for the Tank 41H core sample data. Brine streams and solids salts were compared with the model. Work continued on Tank 38H salt cake simulant experiments. Recent data obtained from ICP on pure solutions of sodium aluminate demonstrated formulation inconsistencies within the results. Due to a corrected formula and weight for sodium aluminate (0.5785 NaAlO2.0.0484 Al(OH)3.0.02071 NaOH.0.17 H2O, FW 63.1 g/mol), new ESP models are underway and a new salt cake was prepared for a flow through experiment.
Formal evaluation of the zeolite database, originally developed for quantifying the behavior of aluminum and aluminum silicates in SRS waste processes is in progress. The database was received and is being tested using additional solubility data available in the literature. Results from this work will indicate the need, if any, for more solubility experiments or additional data regression.
On-line Analysis for Defense Waste Processing Facility
Laser induced breakdown spectroscopy: DWPF project. The progress in making glass samples for LIBS calibration is slower than expected because there are still some technical problems. One glass sample was made during the work period. We have recorded LIBS data with this glass sample under different experimental setups and found that we can use lower laser energy (half of the laser energy used in pellet sample measurements) to achieve the same detection sensitivity as with the pellet sample. The RSTD of the LIBS glass measurement is better than 6% for all the major elements. The sludge samples from DWPF for the initial sludge sample test were received. We plan to have some experiments with both the sludge sample and the glass made from the sludge sample.
Support of Production of High Waste Loading Glasses in the DWPF
DIAL has performed TGA and DSC analyses on the 155% and 185% acid stoichiometry samples sent by SRS. The heating rate was 20 K/min. The results are presently being analyzed. White crystals appeared on the surface of both materials after drying at 100°C. The amount of white crystalline material appears to be higher on the surface of the 185% material. Analyses will be conducted on Frit 418, the white material, and the SRAT output to understand the contribution of the components to the spectra. Both materials appeared to lose weight in approximately the same amounts. We have designed an apparatus to observe the different melt rates of pellets of the material dried at 100°C; the apparatus is currently being built.
Results from the preliminary TGA and DSC analyses on the simulated SME outputs indicate a decomposition reaction with loss of mass, probably sodium formate, occurs around 270°C. We are trying to confirm this hypothesis.
The DSC spectra of material that has undergone the full drying cycle (including the 900°C step) show what appears to be the beginning of a melting transition around 473°C for the 155% material and around 482°C for the 185% material. Peaks that suggest crystallization occur at higher temperatures. We are planning to repeat the DSC analysis of the material that underwent only the drying cycle using several heating and cooling cycles at a lower heating rate to better understand the observed peaks.
Other techniques will be employed as needed to understand the phenomena occurring when the SME material is heated. Part of the SME output will also melted into glass and given to Dr. Singh for LIBS analysis.
Task 5
HEPA Filter Performance Assurance
Regenerable HEPA Filter Performance Testing
During the month of May, the new gear pump was calibrated on the test stand. Testing showed a very stable mass generation rate. A fourth loaded filter test was performed using the cyclone to ensure that the filter was loaded with particles at the low end of the particle size distribution. The ELPI (electrical low pressure impactor) diluters were calibrated with soot. Size fractionated samples consisting of soot, chlorinated soot, and brominated soot were collected and sent to Dr. Barry Dellinger at LSU for analysis.