Fiscal Year 1994

The purpose of these experiments was to study the dissolution, retention, volatilization, and trapping of transuranic radionuclide elements (TRUs), mixed fission and activation products, and high vapor pressure metals (HVPMS) during processing in a high temperature arc furnace. In all cases, surrogate elements (lanthanides) were used in place of radioactive ones. The experiments were conducted utilizing a small DC arc melter developed at the Idaho National Engineering Laboratory (INEL) Research Center (IRC). The small arc melter was originally developed in 1992 and has been used previously for waste form studies of iron enriched basalt (IEB) and IEB with zirconium and titanium additions (IEB4). Section 3 contains a description of the small arc melter and its operational capabilities are discussed in Chapter 4. The remainder of the document describes each testing program and then discusses results and findings

Nonequilibrium diagnostics of plasma thrusters

This paper describes possible techniques by which the state of plasma thruster operation for space propulsion can be determined from a minimum set of experimental data in the laboratory. The kinetic properties of the nonequilibrium plasma plume usually can not be directly related to the observed radiation; hence, appropriate nonequilibrium diagnostic techniques must be employed. A newly developed multithermal, multichemical equilibrium method is discussed that uses measured line emission intensities and N equations to solve for N unknowns. The effect of arbitrarily changing the number of selected N unknowns and how one determines the optimum (minimum) number to be used for a given composition is also presented. The chemical nonequilibrium aspects and the application to molecular species have not yet been published. The important conclusions are that (1) complete thermodynamic systems in nonequilibrium can be described by relatively few variables if appropriate choices and filtering methods are used, (2) a few radiation measurements can yield valid kinetic properties, and (3) the major question in the relations to be used is in the form of the law of mass action. The results are substantiated in the laboratory by additional alternative methods of measurement of some of the kinetic properties. 13 refs., 1 fig

Energy considerations for steam plasma gasification of black liquor and chemical recovery

This paper investigates the energy economics of using a hybrid steam plasma process to gasify black liquor. In the pulp and paper industry, gasification is gaining credibility as an incremental method to supplement the standard Kraft process, which bums the black liquor in large furnaces to recover energy and inorganic chemicals (sodium and sulfur) that are recycled back into the wood pulping process. This paper shows that despite the energy intensive nature of steam plasma processing, several fortuitous conditions arise that make it a viable technology for the gasification of black liquor

Summary of INEL research on the iron-enriched basalt waste form

This report summarizes the knowledge base on the iron-enriched basalt (IEB) waste form developed at the Idaho National Engineering Laboratory (INEL) during 1979--1982. The results presented discuss the applicability of IEB in converting retrieved transuranic (TRU) waste from INEL's Radioactive Waste Management Complex (RWMC) into a vitreous/ceramic (glassy/rock) stable waste form suitable for permanent disposal in an appropriate repository, such as the Waste Isolation Pilot Plant (WIPP) in New Mexico. Borosilicate glass (BSG), the approved high-level waste form, appears unsuited for this application. Melting the average waste-soil mix from the RWMC produces the IEB composition and attempting to convert IEB to the BSG composition would require additions of substantial B{sub 2}0{sub 3}, Na, and SiO{sub 2} (glass frit). IEB requires processing temperatures of 1400 to 1600{degrees}C, depending upon the waste composition. Production of the IEB waste form, using Joule heated melters, has proved difficult in the past because of electrode and refractory corrosion problems associated with the high temperature melts. Higher temperature electric melters (arc and plasma) are available to produce this final waste form. Past research focused on extensive slag property measurements, waste form leachability tests, mechanical, composition, and microstructure evaluations, as well as a host of experiments to improve production of the waste form. Past INEL studies indicated that the IEB glass-ceramic is a material that will accommodate and stabilize a wide range of heterogeneous waste materials, including long lived radionuclides and scrap metals, while maintaining a superior level of chemical and physical performance characteristics. Controlled cooling of the molten IEB and subsequent heat treatment will produce a glass-ceramic waste form with superior leach resistance

Mechanisms of Soil Aggregates Stability in Purple Paddy Soil under Conservation Tillage of Sichuan Basin, China

Part 1: Decision Support Systems, Intelligent Systems and Artificial Intelligence ApplicationsInternational audienceRidge culture is a special conservation tillage method, but the long-term influence of this tillage system on soil aggregate-size stability in paddy fields is largely unknown in southwest of china. The objectives of this paper are to evaluate soil aggregates stability and to determine the relationship between SOC and soil aggregate stability. Soil samples at 0-20 cm layer were adopted from a long-term (16 yr) field experiment including conventional tillage: plain culture, summer rice crop and winter upland crop under drained conditions (PUR-r), and conservation tillage: ridge culture without tillage, summer rice and winter fallow with floodwater layer annually (NTR-f), and winter upland crop under drained conditions (NTR-r), and wide ridge culture without tillage, summer rice crop and winter upland crop under conditions (NTRw-r), respectively. The determination of aggregate-size stability distribution involves the assumptions that soil aggregates can be categorized in terms of their size and water stability (slaking resistance). Experimentally this procedure involves the slaked and capillary-wetted pretreatments; and a subsequent slaking treatment of aggregates >0.250 mm in size. WSMA and NMWD were applied to simulate the breakdown mechanisms of aggregates for studying soil stability based on aggregate resistance to slaking in paddy soil. The results showed that the amount of aggregates-size was greatly observed in the fraction of 2~6.72 mm under ridge culture in paddy soil (more than 50%) under slaking and capillary-wetting pretreatment. The proportion of soil macro-aggregates (>0.25 mm) in conservation tillage was greatly higher than that in conventional tillage under subsequent slaking treatment. Minimal differences of aggregate stability between slaking and wetting were observed, while significant differences were found between ridge culture and plain culture. The aggregates stability under slaking treatment ranked in the order of NTR-r>NTRw-r>NTR-f>PUR-r, while under wetting was NTRw-r>NTR-r>NTR-f>PUR-r, respectively. There was a positive correlation between the aggregates stability and SOC concentrations under wetting, and low correlation was observed under slaking pretreatment. Soil exposure with tillage and lack of rice/rape-seed stubble inputs caused declines in aggregation and organic carbon, both of which make soil susceptible to water erosion. Adoption of ridge culture with no-tillage integrated with crop rotation and stubble mulch significantly alter soil organic concentration, suggesting it was a valuable conservation practice for soil aggregation and soil organic carbon sequestration on paddy soil