Immobilization of chloride-rich radioactive wastes produced by pyrochemical operations

A a result of its former role as a producer of nuclear weapons components, the Rocky Flats Environmental Technology Site (RFETS), Golden, Colorado accumulated a variety of plutonium-contaminated materials. When the level of contamination exceeded a predetermined level (the economic discard limit), the materials were classified as residues rather than waste and were stored for later recovery of the plutonium. Although large quantities of residues were processed, others, primarily those more difficult to process, remain in storage at the site. It is planned for the residues with lower concentrations of plutonium to be disposed of as wastes at an appropriate disposal facility, probably the Waste Isolation Pilot Plant (WIPP). Because the plutonium concentration is too high or because the physical or chemical form would be difficult to get into a form acceptable to WIPP, it may not be possible to dispose of a portion of the residues at WIPP. The pyrochemical salts are among the residues that are difficult to dispose of. For a large percentage of the pyrochemical salts, safeguards controls are required, but WIPP was not designed to accommodate safeguards controls. A potential solution would be to immobilize the salts. These immobilized salts would contain substantially higher plutonium concentrations than is currently permissible but would be suitable for disposal at WIPP. This document presents the results of a review of three immobilization technologies to determine if mature technologies exist that would be suitable to immobilize pyrochemical salts: cement-based stabilization, low-temperature vitrification, and polymer encapsulation. The authors recommend that flow sheets and life-cycle costs be developed for cement-based and low-temperature glass immobilization

Finance fragmented? Frankfurt and Paris as European financial centres after Brexit

Brexit creates an opportunity for alternative European financial centres. However, no comprehensive empirical analysis of the strategic positioning of actors within these financial centres has been conducted. In this article we outline findings from an extensive research project which we conducted in Frankfurt and Paris, two of the main ‘rivals’ to the City of London, in the aftermath of Brexit. We outline the core findings from this project and argue that the emerging competition between Frankfurt and Paris is shaped through four related axes: diversity, path dependency, territory and regulatory stability. Our analysis has implications for two bodies of literature within EU studies. First, inter-governmentalist and supra-nationalist approaches would benefit from interrogating more closely the contested sub-national politics of financial centres. Second, our analysis adds to a growing body of literature on European disintegration by interrogating the interaction of fragmentary and integrative dynamics in the sphere of European finance

Cement technology for borehole plugging: an interim report on permeability measurements of cementitious solids

The permeability of borehole plug solids and plug-wall rock junctions is a property of major interest in the Borehole Plugging Program. This report describes the equipment and techniques used to determine the permeabilities of possible borehole plugging materials and presents results from tests on various cementitious solids and plug-rock combinations. The cementitious solids were made from mixtures of cement, sand, salt, fly ash, and water. Three different types of cement and four different fly ashes were used. Permeabilities ranged from a high value of 3 x 10/sup -4/ darcy for a neat cement paste to a low of 5 x 10/sup -8/ darcy for a saltcrete containing 30 wt % sodium chloride. Miniature boreholes were made in the following four different types of rock: Westerly granite, Dresser basalt, Sioux quartzite, and St. Cloud granodiorite. These small holes were plugged with a mix consisting of 23 wt % Type I Portland cement, 20 wt % bituminous fy ash, 43.2 wt % sand, and 13.8 wt % water. After curing for 91 days at ambient temperature, the permeability of the plug-wall rock junctions ranged from 3 x 10/sup -5/ to < 1 x 10/sup -8/ darcy. Three of the four miniature plugged boreholes exhibited permeabilities of < 10 microdarcys

Grouting as a waste immobilization/disposal method

This presentation will discuss grouting. This presentation will discuss the application of a variety of cement-based grouting techniques available for disposal of environmentally harmful materials. Areas discussed are in situ grouting of pits, ponds and lagoons, grouting as remedial action, and fixation for disposal in burial trenches or vaults. 6 refs., 5 figs., 3 tabs

Glass Science tutorial lecture No. 5: Historical review of USDOE tank waste management

This is a two day course whose objective is to present an unbiased historical overview of the DOE tank waste activities. World events which impacted the US nuclear program (or vise versa) will be presented. Liquid, mostly tank waste, and sludge are the primary concerns of this course

Rheological characterization of cementitious grouts used to dispose of intermediate-level radioactive waste by hydrofracturing at Oak Ridge National Laboratory

The hydrofracturing process is a waste disposal process in use at the Oak Ridge National Laboratory for the permanent disposal of locally generated waste solutions. This process is now being modified for use in the disposal of sludge that results from the sodium hydroxide neutralization of acid waste solutions. In this process, the sludges will be slurried in a bentonite clay suspension and mixed with a solids blend of cement and other additives. The amount of dry solids required for each liter of waste slurry will be determined from a rheogram that relates the viscosity of the slurry with the grams per liter recommended for grouts with desirable flow properties. A description of the process and the development of rheograms are included. Data are presented on the use of chemical additives to control the flow properties of grouts

Concurrent reduction and distillation: an improved technique for the recovery and chemical refinement of the isotopes of cadmium and zinc

The Electromagnetic Isotope Separations Program of the Oak Ridge National Laboratory has been involved in the separation, chemical recovery, and refinement of the stable isotopes of cadmium and zinc since 1946. Traditionally, the chemical refinement procedures for these elements consisted of ion exchange separations using anion exchange resins followed by pH-controlled hydrogen sulfide precipitations. The procedures were quite time-consuming and made it difficult to remove trace quantities of sulfur which interferes in subsequent attempts to prepare rolled metal foils. As demands for /sup 113/Cd and /sup 68/Zn (a precursor for the production of the radiopharmaceutical /sup 67/Ga) increased, it became evident that a quicker, more efficient refinement procedure was needed. Details of an improved method, which employs concurrent hydrogen reduction and distillation in the recovery and refinement of isotopically enriched zinc, are described. Modifications of the procedure suitable for the refinement of cadmium isotopes are also described. 3 figures, 1 table

Waste disposal by shale fracturing at ORNL

Shale fracturing is a process currently being used at the Oak Ridge National Laboratory for the permanent disposal of locally generated waste solutions. In this process, the waste is mixed with a solids blend of cement and other additives; the resulting grout is then injected into an impermeable shale formation at a depth of 700 to 1000 ft. A description of the process, the monitoring techniques that have been developed, the leach rates that have been observed, and some considerations of the impact on the environment are discussed

Recent hydrofracture operations at Oak Ridge National Laboratory

The hydrofracture process is currently being used at Oak Ridge National Laboratory (ORNL) for the permanent disposal of locally generated radioactive waste solutions and slurries. In this process, the waste solution or slurry is mixed with a blend of cement and other solid additives; the resulting grout is then injected into an impermeable shale formation at a depth of 200 to 300 m (700 to 1000 ft). The grout sets a few hours after completion of the injection, fixing the radioactive waste in the shale formation. A new facility was built in 1980-1982 at a site adjacent to the original facility. Between June 1982 and January 1984, more than eight million liters (2.2 million gal) of waste containing over 750,000 Ci were mixed with a blend of solids and injected. Various operating problems were experienced and solved. 6 references, 6 figures, 1 table

Partitioning of cesium in hydrofracture grouts

Phase characterization of hydrofracture grouts was accomplished with the use of optical microscopy, scanning electron microscopy, x-ray diffraction, and ..beta..-..gamma.. autoradiography. A laboratory-produced sample containing 1 wt % stable cesium and an actual hydrofracture grout sheet obtained by core dirlling were examined during this work. The phases present in these samples were identified and cesium was found to be absorbed almost entirely by illite clay agglomerates. These clay agglomerates were tightly bound within the grout structure by hydrated calcium silicates. The ..beta..-..gamma.. autoradiography of the core-drilled sample verified that cesium and other radionuclides were trapped within the 20-year-old grout and had not migrated into trapped shale fragments. 14 references, 3 figures, 1 table