September 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

Accelerating Phytoremediation by Monitoring Plant Status

During the month of September, we analyzed samples and data for the mercury phytoremediation experiment that we finished in July. We have also been writing and revising papers based on earlier experiments. We ordered more ferns and plan to start another round of mercury phytoremediation experiments in October.

Task 2

Support of Hanford Single Shell Tank Waste Disposition

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

DIAL had a conference phone call with Hanford on September 2. Our progress to date was reported and future efforts were discussed. As a result of this conference call, Hanford has provided DIAL with information about the Hanford waste tanks that will help us in preparing our systems for deployment at Hanford.

Stereovision. During September, the stereovision effort investigated the possibility of using Pulnix cameras rather than Sony block cameras. The Pulnix cameras were found to produce better quality images and hence better disparity maps. However, the Pulnix cameras do not have computer-controlled zoom capability (as the Sony block cameras do); for application in the Hanford waste tanks, the ability to zoom is expected to be essential. For other applications, the Pulnix cameras might be a better choice. We are continuing our efforts to investigate the effects on stereovision performance of different parameters, such as distance between cameras, working distance, window size for disparity map computation, etc. Issues related to design of the deployable instrumentation package will also be addressed.

Laser-induced fluorescence-spectral imaging. During this month, the LIF-SI effort began working with surrogate samples in order to optimize experimental conditions before recording LIF spectra of simple uranium and thorium compounds.

Microwave-induced plasma-cavity ringdown spectroscopy. A manuscript entitled "Measurements of Elemental Mercury Using Atmospheric Pressure Microwave Plasma Cavity Ringdown Spectroscopy" is being prepared. This work reports the first plasma ringdown measurements of elemental mercury under atmospheric conditions. The mercury hyper fine structures were also observed. Detection limit of mercury obtained with an open-end plasma torch is 1.5 parts-per-billion. The laser beam path-length of this plasma torch is only 2 mm. Detection sensitivity is expected to be further improved by using a T-shape plasma torch, which will increase the pathlength by a factor of 15 - 20. Efforts focusing on system optimization and improvement of plasma torch design are underway.

Fiber optic sensors. During September, the fiber optic sensors effort concentrated on a literature research to find techniques for synthesizing quantum dots of CdSe, CdS, or ZnS. These quantum dots are highly fluorescent. The literature reports that these materials have been incorporated into polymers and a (CdSe)ZnS core/shell quantum dot incorporated polymer has been tested for neutron detection. Several reversed micelle techniques have been reported for CdSe, CdS, ZnS semiconductor quantum dot synthesis.

Fourier transform profilometry. During September, the FTP probe development effort continued work on the design of the probe support tower. A finite element analysis to analyze the deflection of the support tower was begun. Materials for the probe support tower have been ordered. A new control unit for the probe traverse control has been identified. FTP measurements continued at simulated target distances. Improvement of the fringe pattern projection is underway. Software problems resulting in inconsistent FTP analysis results have been resolved. Further simulation measurement/analysis is underway. Fabrication of sheet metal cones of various sizes is underway in order to simulate different target sizes/volumes.

Process Chemistry and Operations Planning for Hanford Waste Alternatives

A number of the aluminum - nitrate and aluminum - phosphate systems have reached equilibrium after five months. These systems are currently being separated and diluted for analysis by ICP and IC. A study of the equilibration kinetics for the aluminum - nitrate system has begun. Comparison of the experimental, results with the ESP model predictions using various databases will begin following analysis of the experimental data.

Flexible Scintillating Optical Fiber Sensor for Determination of Liquid Level

Efforts to expand and improve upon the flexible scintillating optical fiber sensor technique were initiated during this reporting period. Literature searches were conducted for CdSe, CdS, and ZnS quantum dot synthesis procedures as a potential guideline for incorporation of these highly fluorescent materials into a fiber optic sensor. Several reports regarding reverse micelle synthesis methods for producing CdSe, CdS, ZnS semiconductor quantum dots were obtained. Upon completion of the literature searches and subsequent evaluations, a research plan for developing a quantum dot fiber optic sensor will be developed.

Task 3

Disposition of Idaho HLW Calcine

Support of INEEL Calcine Disposition Project

We continued experimentation aiming to formulating a Fe-P ceramic having a suitable setting time. After several experiments with various amount of ferric oxide in the waste form, the problem was tracked to problems with the ceramic-grade magnetite we have been using. Waste forms prepared with high purity magnetite and no ferric oxide set within 24 hours, while waste form prepared with the "cheap" magnetite need several days to set. Since the use of high purity magnetite would render prohibitive the cost of stabilizing large amounts of calcine, we will experiment with additives to shorten the setting time. For what concerns the hydroceramic cement, we have developed a few formulations that are pourable, and we are trying to determine the optimal curing procedure. The grout formulation provided by ICP-SP3 produced a workable waste form. We will perform scoping runs at the beginning of October.

Task 4

Support of SRS Salt Disposition and Other SRS Alternatives

Support for SRS Salt Disposition Alternatives

A simulant formulation for SRS Tank 37H was evaluated and prepared. The simulant contains high sodium carbonate loadings and equal molar amounts of silicon and aluminum. TGA analysis was performed and results demonstrated a water content of 38.7% which closely resembles the actual waste water content of 35.7%. Preparations for a new DASR experiment in a controlled environment at 30°C were begun. ESP calculations are in progress. Initial observation of the simulant poured into the column indicated a small (top) layer of white particles. The layer is undergoing testing and is expected to be comprised of small gibbsite particles. Previous lab-scale salt cake dissolution experiments using a Hanford recipe also revealed a layer formation. Based on this tentative assignment it is expected that the DASR experiment will take considerably longer with the 37H simulant as compared to the composition based on either SRS tanks 38H or 41H.

On-line Analysis for Defense Waste Processing Facility

During this reporting period, the work on sludge sample measurement progressed slower than expected due to lack of manpower and the different slurry samples for calibration. A scheduled conference call with DWPF staff (Peeler, Herman and Marra) to identify the appropriate simulant and provide the physical parameters of the slurry which are needed to design a sludge sampling system was postponed. Most efforts for this month were on testing various data processing techniques to improve the measurement accuracy and precision. A calibration-free technique (no need for the calibration data), which uses the acquired atomic line intensity and spectroscopic data to calculate the elemental concentration, was tested previously, with the data from a different detection system (SPEX 500 M spectrometer + diode array detector). A large error was found in the concentration measurement. The error is mainly due to the uncertainty in the spectroscopic constants and the inferred plasma temperature and electron density used in the calculation. The calibration technique provides much better measurement accuracy than the calibration-free technique; however, it depends on the available calibration samples. To improve the calibration-free technique so we can still make LIBS measurements even when the calibration data are not available, various analytic line intensities were calculated based on the concentration from ICP analysis and compared with the experimental data. With detailed analysis, we found there are two issues which need to be solved before this technique becomes practical. First, we need a calibrated spectral lamp for correcting the spectral response between 200 - 800 nm. This lamp needs to be purchased as soon as funds are available. Second, the self-absorption found in most analyte lines make quantitative analysis impossible. It is complicated to correct self absorption theoretically and requires the knowledge of some plasma parameters. We will first concentrate on reducing or eliminating the effect of self-absorption by using time and spatial resolving techniques.

Support of Production of High Waste Loading Glasses in the DWPF

Experiments have begun looking at temperatures below the usual melting point of 1150 °C to examine the reaction between the frits and the surrogate waste slurry (Case 7d SRAT product). Samples of the frit/slurry mixture heated to 700, 800 and 900 °C have been polished for examination with optical and electron microscopy. Photos have been taken with the optical microscope. SEM will be done next month.

Task 5

HEPA Filter Performance Assurance

Regenerable HEPA Filter Performance Testing

Testing for the month of September included challenging Porvair sintered metal filters with potassium chloride and iron aerosols. The Porvair filters are 47 mm in diameter. The potassium chloride (KCl) used for testing was 30% by weight KCl dissolved in de-ionized water. The iron aerosol was 30% by weight FeSO₄ solution dissolved in de-ionized water. The Porvair filters were washed with acid and loaded alternately with particulate three times each. Method 5i measurements were performed during testing also. The filters were loaded at low relative humidity and high relative humidity in the HEPA filter test stand.

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