Radioactive and nonradioactive waste intended for disposal at the Waste Isolation Pilot Plant

Transuranic (TRU) waste generated by the handling of plutonium during research on or production of U.S. nuclear weapons will be disposed of in the Waste Isolation Pilot Plant (WIPP). This paper describes the physical and radiological properties of the TRU waste that will be deposited in the WIPP. This geologic repository will accommodate up to 175,564 m³ of TRU waste, corresponding to 168,485 m³ of contact-handled (CH-) TRU waste and 7079 m³ of remote-handled (RH-) TRU waste. Approximately 35% of the TRU waste is currently packaged and stored (i.e. legacy) waste, with the remainder of the waste to be packaged or generated and packaged in activities before the year 2033, which is the closure time for the repository. These wastes were produced at 27 U.S. Department of Energy (DOE) sites in the course of generating defense nuclear materials. The radionuclide and nonradionuclide inventories for the TRU wastes described in this paper were used in the 1996 WIPP Compliance Certification Application (CCA) performance assessment calculations by the Sandia National Laboratories/New Mexico (SNL/NM).     

Biosphere models in radioactive waste disposal assessment

This paper briefly discusses the uncertainties associated with predictions made using biosphere models in assessments of radioactive waste repositories. Typical models, processes influencing transport and accumulation of radionuclides and the subsequent pathways evaluation are described. Reducible and non-reducible uncertainties are presented as well as some conclusions about the predictive power of the models.     

Risk management and the landfill in hazardous waste disposal

Amidst the current dialogue surrounding drives at state and federal levels to ban the use of landfills for certain hazardous wastes, it is easy to lose     

Treatment of waste printed wire boards in electronic waste for safe disposal

The printed wire boards (PWBs) in electronic waste (E-waste) have been found to contain large amounts of toxic substances. Studies have concluded that the waste PWBs are hazardous wastes because they fails the toxicity characteristic leaching procedure (TCLP) test with high level of lead (Pb) leaching out. In this study, two treatment methods - high-pressure compaction and cement solidification - were explored for rendering the PWBs into non-hazardous forms so that they may be safely disposed or used. The high-pressure compaction method could turn the PWBs into high-density compacts with significant volume reduction, but the impact resistance of the compacts was too low to keep them intact in the environment for a long run. In contrast, the cement solidification could turn the PWBs into strong monoliths with high impact resistance and relatively high compressive strength. The leaching of the toxic heavy metal Pb from the solidified samples was evaluated by both a dynamic leaching test and the TCLP test. The dynamic leaching results revealed that Pb could be effectively confined in the solidified products under very harsh environmental conditions. The TCLP test results showed that the leaching level of Pb was far below the regulatory level of 5mg/L, suggesting that the solidified PWBs are no longer hazardous. It was concluded that the cement solidification is an effective way to render the waste PWBs into environmentally benign forms so that they can be disposed of as ordinary solid wastes or beneficially used in the place of concrete in some applications.     

Leaching of CCA-treated wood: implications for waste disposal

Leaching of arsenic, chromium, and copper from chromated copper arsenate (CCA)-treated wood poses possible environmental risk when disposed. Samples of un-weathered CCA-treated wood were tested using a variety of the US regulatory leaching procedures, including the toxicity characteristic leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP), extraction procedure toxicity method (EPTOX), waste extraction test (WET), multiple extraction procedure (MEP), and modifications of these procedures which utilized actual MSW landfill leachates, a construction and demolition (C and D) debris leachate, and a concrete enhanced leachate. Additional experiments were conducted to assess factors affecting leaching, such as particle size, pH, and leaching contact time. Results from the regulatory leaching tests provided similar results with the exception of the WET, which extracted greater quantities of metals. Experiments conducted using actual MSW leachate, C and D debris leachate, and concrete enhanced leachate provided results that were within the same order of magnitude as results obtained from TCLP, SPLP, and EPTOX. Eleven of 13 samples of CCA-treated dimensional lumber exceeded the US EPA's toxicity characteristic (TC) threshold for arsenic (5 mg/L). If un-weathered arsenic-treated wood were not otherwise excluded from the definition of hazardous waste, it frequently would require management as such. When extracted with simulated rainwater (SPLP), 9 of the 13 samples leached arsenic at concentrations above 5 mg/L. Metal leachability tended to increase with decreasing particle size and at pH extremes. All three metals leached above the drinking water standards thus possibly posing a potential risk to groundwater. Arsenic is a major concern from a disposal point of view with respect to ground water quality.     

Co-landfilling of pretreated waste: disposal and management strategies at lab-scale

The present paper deals with the possible advantages that can be obtained by co-landfilling of municipal solid waste organic fraction (MSWOF) and bottom ash (BA) from the incineration of municipal solid waste. In particular, the aim of the research hereby presented is to check the effect exerted by different disposal (mixed or layered) and management strategies (anaerobic or semiaerobic conditions) for landfills in which MSWOF and BA are co-disposed. Three lab-scale reactors were set-up: the reactor A with mixed BA and MSWOF in anaerobic conditions, the reactor B with mixed BA and MSWOF in semiaerobic conditions, the reactor C with layered BA and MSWOF in anaerobic conditions. The results obtained showed that the aeration at the beginning of the experimental period for about 60 days led to a more rapid biodegradation of the organic matter and to an improved leachate quality in terms of both organic load and nitrogen content. Also a significant increase in the settling rate was observed at the end of the aeration phase. Therefore, the aerobic management can be advised as the most available strategy providing a more rapid biological and mechanical stabilization of the bulk waste. Otherwise, the disposal strategy did not exert any significant effect on the leachate characteristics; however, the layered configuration may be adopted in order to accelerate the main settlements.     

Pure and mixed strategies for the EOQ repair and waste disposal problem

In this paper the analysis of the EOQ repair and waste disposal model with variable setup numbers for production and repair within some collection time interval is continued. The cost analysis is now extended to the extreme waste disposal rates and it is shown that the pure (bang-bang) policy of either no waste disposal (total repair) or no repair (total waste disposal) dominates the strategy of mixing waste disposal and repair. Moreover, the different behavior of the minimum cost, of the optimal setup numbers, lot sizes and collection intervals for small and large waste disposal rates is discussed.     

Thermal characterization of iron phosphate glasses for nuclear waste disposal

This paper reports on the thermal properties of iron phosphate glasses with the following wt.% composition: 40Fe₂O₃–60P₂O₅. Such glasses are currently being investigated for nuclear waste disposal. Open photoacoustic cell (OPC) and heat capacity techniques were performed to determine thermal diffusivity, thermal conductivity and heat capacity of the glasses. Results were compared with borosilicate glass where OPC and Thermal lens where performed. Moreover, the present paper demonstrates the semiconducting-like behavior of iron phosphate glasses.     

A conflict model for the international hazardous waste disposal dispute

A multi-stage conflict model is developed to analyze international hazardous waste disposal disputes. More specifically, the ongoing toxic waste conflicts are divided into two stages consisting of the dumping prevention and dispute resolution stages. The modeling and analyses, based on the methodology of graph model for conflict resolution (GMCR), are used in both stages in order to grasp the structure and implications of a given conflict from a strategic viewpoint. Furthermore, a specific case study is investigated for the Ivory Coast hazardous waste conflict. In addition to the stability analysis, sensitivity and attitude analyses are conducted to capture various strategic features of this type of complicated dispute.     

Application of generic risk assessment software to radioactive waste disposal

Monte Carlo methods are used in a variety of applications such as risk assessment, probabilistic safety assessment and reliability analysis. While Monte Carlo methods are simple to use, their application can be laborious. A new microcomputer software package has been developed that substantially reduces the effort required to conduct Monte Carlo analyses. The Sensitivity and Uncertainty Analysis Shell (SUNS) is a software shell in the sense that a wide variety of application models can be incorporated into it. SUNS offers several useful features including a menu-driven environment, a flexible input editor, both Monte Carlo and Latin Hypercube sampling, the ability to perform both repeated trials and parametric studies in a single run, and both statistical and graphical output. SUNS also performs all required file management functions.     

A survey of monitoring technology for subseabed disposal of radioactive waste

The subseabed is currently being considered as a disposal site for nuclear waste, and if it does become an option, monitoring to detect escape of the disposed material will be essential. In this paper, we define types of nuclear waste and present the dimensions of the monitoring problems that would be encountered in ocean disposal. We then summarize the characteristics of a number of physical, chemical, biological, and ecological monitoring methods. We also describe the advances and developments that will be necessary before the monitoring functions and support systems can be employed.     

航空垃圾焚烧回转窑电气自动控制系统

介绍首都机场垃圾焚烧站航空垃圾焚烧系统电气自动控制系统的构成，并论述其PLC系统、变频调速系统、上位监控系统的特点。该系统配置合理、自动化及可靠性高。     

Synthesis of nuclear waste monazites,ideal actinide hosts for geologic disposal

Monazite, an orthophosphate mineral of the lanthanides (Ln) and the actinides (An) U and Th, is a model for an ideal synthetic mineral waste form for geologic disposal of long-lived nuclear waste actinides. Natural monazites are known to have survived many of the conditions that might be inflicted on a nuclear waste repository by geological disruptions. High Th and U monazites with compositions typical of nuclear wastes have been synthesized with a routine calcination-pelletization-crystallization procedure. Charge balance for the Th⁴⁺ → Ln³⁺ substitution can be provided by either an equimolar Ca²⁺ → Ln³⁺ or Si⁴⁺ → P⁵⁺ substitution. For U⁴⁺ → Ln³⁺, only the Ca²⁺ → Ln³⁺ substitution resulted in a phase-pure monazite. Unit cell parameter data were obtained for each nuclear waste monazite phase.     

Dimensionality of heavy metal distribution in waste disposal sites using nonlinear dynamics

Mapping of heavy metal contamination in mining and waste disposal sites usually relies on geostatistical approaches and linear stochastic dynamics. The present paper aims to identify, using the Grassberger-Procaccia correlation dimension (CD) algorithm, the existence of a nonlinear deterministic and chaotic dynamic behaviour in the spatial pattern of arsenic, manganese and zinc concentration in a Russian coal waste disposal site. The analysis carried out yielded embedding dimension values ranging between 7 and 8 suggesting thus from a chaotic dynamic perspective that arsenic, manganese and zinc concentration in space is a medium dimensional problem for the regionalized scale considered in this study. This alternative nonlinear dynamics approach may complement conventional geostatistical studies and may be also used for the estimation of risk and the subsequent screening and selection of a feasible remediation scheme in wider mining and waste disposal sites. Finally, the synergistic effect of this study may be further elaborated if additional factors including among others presence of hot spots, density and depth of sampling, mineralogy of wastes and sensitivity of analytical techniques are taken into account.     

A study on hydrothermal disposal of sodium arsenate waste from Ga-As processing

Hydrothermal disposal of sodium arsenate waste was investigated with the aim of removing As from solution, and its precipitation as crystalline iron arsenate. The precipitate was characterized by XRD and SEM, and leach tests were conducted to examine the precipitates solubility. The optimum formation condition for crystalline iron arsenate was pH 0.3–1.7, temperature 150–200°C, Fe/As 1.0 and time 10–40 min. Over 98% arsenic in the waste can be precipitated. The solid product is mainly iron arsenate which has a solubility below 5 mg/l. The preliminary work showed that hydrothermal disposal is a feasible option for treatment of sodium arsenate waste.