Monthly Research Progress
Institute for Clean Energy Technology
Support of Oak Ridge Site Closure
Characterization of Corrosion for Closure of Oak Ridge Research Reactor
We have continued our planning for the next deployment into the Oak Ridge Research Reactor (ORRR) pool. We have contacted our collaborators at ORNL and are awaiting selection of a deployment date. With the exception of the demountable instrument faceplate, the new submergible metal box has been constructed. The demountable faceplate of the submergible box is designed so as to enable FTP and stereovision to be able to sequentially record images of the same object of interest without the need to move the box or to open the box for adjustments. A new submergible box is necessary because during our initial deployment of the submergible Fourier transform profilometry (FTP) system into the ORRR pool, a detectable amount of radioactive materials was deposited onto the metal box containing our instrumentation; consequently, ORNL has retained the original box. An uncertainty analysis of our FTP correction methods for image distortion due to Snell's law continues. Efforts continue to characterize FTP spatial resolution using higher resolution cameras.
Bio-availability and Speciation of Mercury in the Oak Ridge Ecosystem
In June, we finished supplemental experiments and all analyses for the study on the dissolution kinetics and dynamics of mercury species by various reagents including saturated Na2S, 4-M HNO3, 12-M HNO3, 1:6:7 HCl-HNO3-H2O (EPA method 3200). We found that Na2S (saturated) could extract all HgS forms from contaminated soils in 2 - 4 hours. This greatly reduces the reaction time required for complete dissolution of HgS from soils and sediments. We also found that dissolution of mercury from HgS contaminated soils by both 4-M HNO3 and 12-M HNO3 increased with time. It is very interesting that both 4-M HNO3 and 12-M HNO3 did not dissolve much pure HgS chemical, but they dissolved up to 6% of total Hg from HgS contaminated Oak Ridge soil. This indicates that soil matrix, especially after a number of plantings, activated HgS. In other words, planting increased the solubility and bioavailability of HgS forms in Oak Ridge soils. This finding could explain why the current Hg level in both fish and water of the creek around Oak Ridge increased in spite of the fact that Hg in flood plains of Oak Ridge is mostly in an HgS form. We also found that 1:6:7 HCl:HNO3:H2O is very effective in dissolving HgS forms from Oak Ridge soils.
In July we will present some of our study at the World Soil Congress in Philadelphia and will write a journal manuscript.
Accelerating Phytoremediation by Monitoring Plant Status
During the month of June, we continued the analysis of plant tissue samples from the latest mercury phytoremediation experiment that was completed in May. Meanwhile, we designed and started to build a series of sunlit chambers for special experiments. The chambers will be used to investigate plant root uptake of soil mercury and leaf intake of atmosphere Hg.
In the coming month, we are planning to conduct more phytoremediation experiments.
Support of Hanford Single Shell Tank Waste Disposition
In-tank/At-tank Characterization for Closure of Hanford Tanks
Stereovision. We tested our newly upgraded SV system (better camera with 20X zoom, new image acquisition board, and updated camera control and image acquisition software). Selected objects at different distances were used for the initial tests. We will process the images and search for the best combination of experimental parameters.
Laser-induced fluorescence-spectral imaging. During June, we continued our attempts to trouble shoot the performance of a currently available camera system until a new camera system can be purchased.
Microwave-induced plasma-cavity ringdown spectroscopy. We continued our effort to transform our laboratory-level ringdown system into a site-deployable instrument for tank vapor characterization. The pressure control of the portable ringdown gas cell was tested this month. Additionally, an evaluation of ringdown as a tool for direct detection of mercury vapor from contaminated sources has been conducted.
Fiber optic sensors. During June, we focused on optimizing the procedure for making scintillating optical fibers. The scintillating optical fibers prepared and tested in our previous work were found not to be transparent. Obviously, the detected scintillating light in our previous tests was from only a very small part of the scintillating fibers. We are optimizing the concentrations of the doped scintillating agents as well as the reaction conditions in order to make transparent scintillating optical fibers.
Fourier transform profilometry. We began preparation of a report describing the results from the first stage of simulation testing. The FTP system is of interest to Hanford because of its potential to reduce operator dependence of the results; in order to quantify the extent to which FTP results are operator dependent, it was decided that the FTP images would be independently analyzed by several members of the FTP team. This effort will also be included in the first stage report. In order to test the ability of critical FTP optical components (Ronchi filter, diffuser) to withstand nuclear radiation, arrangements have been made with MSU's Radiation Safety Officer to utilize MSU's gamma irradiator for an extended test.
Process Chemistry and Operations Planning for Hanford Waste Alternatives
The DBLSLTDB database for use with the OLI System Inc. ESP and Stream Analyzer products has been evaluated against solubility data and earlier simulations and dissolution experiments with Hanford salt cake core samples. Release of the database to engineers at Hanford and Savannah River is expected in early July. Documentation of the database is being performed.
Additional simulations were performed in support of neural network development. These addressed gaps in concentration distributions for a number of anions and cations. The data was forwarded to GenSym and discussions with Hanford personnel are planned following evaluation of the GenSym work.
Disposition of Idaho HLW Calcine
Support of CH2M-WG Calcine Disposition Project
The test plan for the mock up system was issued. Not all details are available at the moment; it will be completed during the final construction of the system. Two bids were received for the feeding systems for the pilot scale system. The award is going to Schenk Accurate for ~ $17 K. The lead time is 10 - 12 weeks. Bids have gone out for the mixer (which we are only renting) and are expected to be received during July. As suggested in the test plan, our schedule has slipped somewhat due to our inability to get permission for ordering equipment due to our budget constraints. We expect to begin shakedown testing of the mock up in October/November 2006.
A larger (about 9 kg) batch of the grout waste form (1:1:1 formulation) was made up this week. No significant differences from the smaller batches were observed. From the remaining simulant materials, we have made up a final 10-kg batch of pre-mixed simulant for any further testing we may decide to do. We are virtually out of the Run 20 product now and wonder if there is a need for obtaining any more of these materials. We will need the "non-hazardous" simulant for the initial mock up testing, and will probably need more of the "hazardous" simulant for final mock up testing. The technical paper "Grout Waste Form for the Disposition of Idaho HLW Calcine" was submitted to the organizers of the annual meeting of the American Ceramic Society to be held this fall. Discussions have started regarding the statement of work for FY 07. A brief draft of the plans will be available in a week or two.
Support of SRS Salt Disposition and Other SRS Alternatives
Modeling and Experimental Support for High-level SRS Waste Disposition
The DASR experiment using the remaining 38H simulant with 1.5% by weight sludge simulant is ongoing with daily diluent additions and fraction removals. New solubility test experiments for the CsNO3-KNO3-Water system have begun at 25°C. Based on results from these test solutions for equilibrium times, additional solutions will be prepared. Modeling and comparison of the FIU SRS 41H aged simulant tall column experiment was completed and is being readied for a topical report.
Process Improvements for the Defense Waste Processing Facility (DWPF)
On-line slurry analysis. To prepare simulated melter feed (SME) products of various compositions for LIBS calibration, various amounts of frit have been added to the base sludge provided by SRNL. Initial work shows that the frit is hard to completely dissolve in sludge due to the bold grain form of the frit. Since LIBS makes point measurements, the sample homogeneity is an essential parameter for the LIBS measurement accuracy. The added glass frit cannot be uniformly suspended in the slurry we prepared, resulting not only in a low silicon LIBS signal but also a high relative standard deviation from these slurry samples as compared with the slurry with the same amount of Si by adding a fine powder of SiO2. To solve these problems, we have ground the frit and stirred it into the slurry using an ultrasonic cleaner. To make a comparative study, ground and unground glass frits were mixed with base sludge separately then boiled to make the final product, a 50% solid. LIBS data from these samples were recorded and compared. The LIBS signals of the major elements in the frit (e.g. Si, Li) from the sample with ground frit appears to be about 1.5 - 2 times higher than the intensity obtained from the sample with the unground frit. Reasonably good RSD (less than 10%) were also obtained from the sample with ground frit. The data in this study was collected using 10-Hz laser frequency; better RSD can be achieved with low laser frequency such as 1 or 5 Hz.
Improvement of waste throughput. The experiments run so far to examine the relative reaction rates of the two frits have not provided the information expected. It appears that the 200 frit reacts more rapidly (at lower temperatures) than the 320 frit, and that's not what has been observed in practice. These tests were done with a dried version of the Case 7d SRAT. Some of them will be re-run using the Case 7d SRAT as a slurry. Future batches to be run at DWPF expect to contain much more alumina. We will set up to run some experiments with aluminum hydroxide added to the Case 7d SRAT slurry.
Support of the Fernald Silos Project
Fernald Silos Project - Remediation Process Support
Final decontamination and disposition of the Fernald building and the associated systems is ongoing. Communication with the Fernald Management Team will continue through project completion.
HEPA Filter Performance Assurance
During June, the first series of media velocity testing was completed. A HEPA filter was loaded from 1.3 to 6 in. w.c. at a media velocity of 6 ft/min. This was the second trial at this media velocity. The previous test was conducted with a particle CMD slightly larger than desired, which resulted in a higher particulate capture than predicted. Writing of a manuscript to be submitted to Reviews of Scientific Instruments describing the ICET aerosol generator was continued, and a companion paper describing the ICET HEPA Filter Test Stand and HEPA Filter Monitoring project was started. As this round of media velocity testing is wrapping up, the HEPA group is turning attention to the evaluation of CeraMem ceramic membrane filters. The filter housing to be used to conduct testing was designed.
Inquiries may be addressed to:Dr. Roger King, Interim Director
205 Research Blvd.
Starkville, MS 39762-5932