DEVELOPMENT OF A SLURRY-FED IN-CAN MELTER FOR NUCLEAR DEFENSE WASTE

The Savannah River Plant (SRP) has about 30 million gallons of high-level, radioactive, liquid waste stored in large waste tanks. This waste is a by-product of the production of nuclear defense materials at SRP. Plans are to build the Defense Waste Processing Facility (DWPF) at SRP to convert this waste into solid form. A key step in the planned DWPF process is the vitrification or glassmaking step, in which the radionuclides are incorporated in borosilicate glass. Two types of glass melters have been developed for this step. The planned melter design for the DWPF is a slurry-fed, continuous, joule-heated melter. The backup melter design is an in-can melter. Previous plans were to dry and partially calcine the radioactive waste sludge before feeding it to the in-can melter. However, it was desirable to eliminate the drying step and feed the waste sludge as a liquid. Eliminating the drying step simplified the process and reduced the project cost. At the Savannah River Laboratory (SRL), a full-scale in-can melter of the former dry-fed design was converted to slurry feeding by adding appropriate feed and off-gas systems. Five experimental runs were made with this process from August to December 1981. The purpose of this program was to demonstrate the basic process, determine key process variables such as rate and off-gas system requirements, and identify potential problems with long-term operation. A full-scale, nonradioactive process has been studied in which a slurry of waste sludge and glass formers is fed to a heated can. Saturated steam is used to cool the off-gas. Initial results show the concept to be technically adequate

HLW Tank Space Management, Final Report

The HLW Tank Space Management Team (SM Team) was chartered to select and recommend an HLW Tank Space Management Strategy (Strategy) for the HLW Management Division of Westinghouse Savannah River Co. (WSRC) until an alternative salt disposition process is operational. Because the alternative salt disposition process will not be available to remove soluble radionuclides in HLW until 2009, the selected Strategy must assure that it safely receives and stores HLW at least until 2009 while continuing to supply sludge slurry to the DWPF vitrification process

1,050 years of hurricane strikes on Long Island in the Bahamas

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Wallace, E. J., Donnelly, J. P., van Hengstum, P. J., Winkler, T. S., McKeon, K., MacDonald, D., d'Entremont, N. E., Sullivan, R. M., Woodruff, J. D., Hawkes, A. D., & Maio, C. 1,050 years of hurricane strikes on long island in the Bahamas. Paleoceanography and Paleoclimatology, 36(3), (2021): e2020PA004156, https://doi.org/10.1029/2020PA004156.Sedimentary records of past hurricane activity indicate centennial-scale periods over the past millennium with elevated hurricane activity. The search for the underlying mechanism behind these active hurricane periods is confounded by regional variations in their timing. Here, we present a new high resolution paleohurricane record from The Bahamas with a synthesis of published North Atlantic records over the past millennium. We reconstruct hurricane strikes over the past 1,050 years in sediment cores from a blue hole on Long Island in The Bahamas. Coarse-grained deposits in these cores date to the close passage of seven hurricanes over the historical interval. We find that the intensity and angle of approach of these historical storms plays an important role in inducing storm surge near the site. Our new record indicates four active hurricane periods on Long Island that conflict with published records on neighboring islands (Andros and Abaco Island). We demonstrate these three islands do not sample the same storms despite their proximity, and we compile these reconstructions together to create the first regional compilation of annually resolved paleohurricane records in The Bahamas. Integrating our Bahamian compilation with compiled records from the U.S. coastline indicates basin-wide increased storminess during the Medieval Warm Period. Afterward, the hurricane patterns in our Bahamian compilation match those reconstructed along the U.S. East Coast but not in the northeastern Gulf of Mexico. This disconnect may result from shifts in local environmental conditions in the North Atlantic or shifts in hurricane populations from straight-moving to recurving storms over the past millennium.This work was funded by the National Science Foundation Graduate Research Fellowship (to E. J. W.), the Dalio Explore Foundation, and National Science Foundation grant OCE-1356708 (to J. P. D. and P. J. vH.)

Historically unprecedented Northern Gulf of Mexico hurricane activity from 650 to 1250 CE

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Rodysill, J. R., Donnelly, J. P., Sullivan, R., Lane, P. D., Toomey, M., Woodruff, J. D., Hawkes, A. D., MacDonald, D., d'Entremont, N., McKeon, K., Wallace, E., & van Hengstum, P. J. Historically unprecedented Northern Gulf of Mexico hurricane activity from 650 to 1250 CE. Scientific Reports, 10(1), (2020): 19092. doi:10.1038/s41598-020-75874-0.Hurricane Michael (2018) was the first Category 5 storm on record to make landfall on the Florida panhandle since at least 1851 CE (Common Era), and it resulted in the loss of 59 lives and $25 billion in damages across the southeastern U.S. This event placed a spotlight on recent intense (exceeding Category 4 or 5 on the Saffir-Simpson Hurricane Wind Scale) hurricane landfalls, prompting questions about the natural range in variability of hurricane activity that the instrumental record is too short to address. Of particular interest is determining whether the frequency of recent intense hurricane landfalls in the northern Gulf of Mexico (GOM) is within or outside the natural range of intense hurricane activity prior to 1851 CE. In this study, we identify intense hurricane landfalls in northwest Florida during the past 2000 years based on coarse anomaly event detection from two coastal lacustrine sediment archives. We identified a historically unprecedented period of heightened storm activity common to four Florida panhandle localities from 650 to 1250 CE and a shift to a relatively quiescent storm climate in the GOM spanning the past six centuries. Our study provides long-term context for events like Hurricane Michael and suggests that the observational period 1851 CE to present may underrepresent the natural range in landfalling hurricane activity.Funding for this project was provided by the Strategic Environmental Research and Development Program (SERDP) grant and NSF awards 0903020, 1902463, and 1854980 awarded to Jeffrey Donnelly, and the USGS Land Change Science Program

High-Level Waste System Process Interface Description

The High-Level Waste System is a set of six different processes interconnected by pipelines. These processes function as one large treatment plant that receives, stores, and treats high-level wastes from various generators at SRS and converts them into forms suitable for final disposal. The three major forms are borosilicate glass, which will be eventually disposed of in a Federal Repository, Saltstone to be buried on site, and treated water effluent that is released to the environment

CHARACTERIZATION OF TANK 17 RESIDUAL WASTE

Plans are to close Tank 17, a type IV waste tank in the F-area Tank Farm, by filling it with pumpable backfills. Most of the waste was removed from the tank in the late 1980s, and the remainder of the waste was removed in a short spray washing campaign that began on 11 April 1997. More details on the planned closure can be found in the Closure Plan for the High-Level Waste (HLW) Tanks and the specific closure module for Tank 17. To show that closure of the tank is environmentally sound, a performance evaluation has been performed for Tank 17. The performance evaluation projected the concentration of contaminants at various locations and times after closure. This report documents the basis for the inventories of contaminants that were used in the Tank 17 performance evaluation

Satellite retrieval of the liquid water fraction in tropical clouds between −20 and −38 °C

This study describes a satellite remote sensing method for directly retrieving the liquid water fraction in mixed phase clouds, and appears unique in this respect. The method uses MODIS split-window channels for retrieving the liquid fraction from cold clouds where the liquid water fraction is less than 50% of the total condensate. This makes use of the observation that clouds only containing ice exhibit effective 12-to-11 μm absorption optical thickness ratios (β<sub>eff</sub>) that are quasi-constant with retrieved cloud temperature <i>T</i>. This observation was made possible by using two CO<sub>2</sub> channels to retrieve <i>T</i> and then using the 12 and 11 μm channels to retrieve emissivities and β<sub>eff</sub>. Thus for <i>T</i> < −40 °C, β<sub>eff</sub> is constant, but for <i>T</i> > −40 °C, β<sub>eff</sub> slowly increases due to the presence of liquid water, revealing mean liquid fractions of ~ 10% around −22 °C from tropical clouds identified as cirrus by the cloud mask. However, the uncertainties for these retrievals are large, and extensive in situ measurements are needed to refine and validate these retrievals. Such liquid levels are shown to reduce the cloud effective diameter <i>D</i><sub>e</sub> such that cloud optical thickness will increase by more than 50% for a given water path, relative to <i>D</i><sub>e</sub> corresponding to pure ice clouds. Such retrieval information is needed for validation of the cloud microphysics in climate models. Since low levels of liquid water can dominate cloud optical properties, tropical clouds between −25 and −20 °C may be susceptible to the first aerosol indirect effect

Development of a slurry-fed in-can melter for nuclear defense waste

In-Can Melting is the backup vitrification process for Savannah River Plant waste. A full-scale, nonradioactive process has been studied in which a slurry of waste sludge and glass formers is fed to a heated can. Saturated steam is used to cool the off-gas. Initial results show the concept to be viable. 4 figures

Inferring Cirrus Size Distributions Through Satellite Remote Sensing and Microphysical Databases

Since cirrus clouds have a substantial influence on the global energy balance that depends on their microphysical properties, climate models should strive to realistically characterize the cirrus ice particle size distribution (PSD), at least in a climatological sense. To date, the airborne in situ measurements of the cirrus PSD have contained large uncertainties due to errors in measuring small ice crystals (D<60 m). This paper presents a method to remotely estimate the concentration of the small ice crystals relative to the larger ones using the 11- and 12- m channels aboard several satellites. By understanding the underlying physics producing the emissivity difference between these channels, this emissivity difference can be used to infer the relative concentration of small ice crystals. This is facilitated by enlisting temperature-dependent characterizations of the PSD (i.e., PSD schemes) based on in situ measurements. An average cirrus emissivity relationship between 12 and 11 m is developed here using the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite instrument and is used to retrieve the PSD based on six different PSD schemes. The PSDs from the measurement-based PSD schemes are compared with corresponding retrieved PSDs to evaluate differences in small ice crystal concentrations. The retrieved PSDs generally had lower concentrations of small ice particles, with total number concentration independent of temperature. In addition, the temperature dependence of the PSD effective diameter De and fall speed Vf for these retrieved PSD schemes exhibited less variability relative to the unmodified PSD schemes. The reduced variability in the retrieved De and Vf was attributed to the lower concentrations of small ice crystals in the retrieved PSD