Field validation of cable monitoring and rating system (CMARS) laboratory model. First semi-annual report, 1 November 1978-30 April 1979

The goal of this project is to quantitatively validate the Cable Monitoring and Rating System (CMARS) software and associated hardware as applied to commercially operating underground transmission systems which are representative of the bulk of this type of system used in the USA. In the course of the project, it is expected that improvements and refinements of the CMARS will occur resulting in improved accuracy, flexibility and predictive capability for CMARS. The circuits to be utilized are equipped with extensive monitoring facilities, which will allow the determination of CMARS accuracy. In addition, recommendations will be made regarding accuracy vs. cost tradeoffs as a function of the amount and complexity of data which might be available on or retrofitted to existing systems, or considered for future systems. Information displays will be optimized by discussions with system operators, transmission planners and underground transmission engineering groups. Finally, hardware installation problems for sensor equipment as well as data acquisition equipment will be readily identified. At the completion of the proposed work, specifications for CMARS software and hardware, and all associated sensor, data acquisition and communications equipment will be available to the industry. The first semi-annual report on the project is presented

Contribution of Energetically Reactive Surface Features to the Dissolution of CeO2 and ThO2 Analogues for Spent Nuclear Fuel Microstructures

In the safety case for the geological disposal of nuclear waste, the release of radioactivity from the repository is controlled by the dissolution of the spent fuel in groundwater. There remain several uncertainties associated with understanding spent fuel dissolution, including the contribution of energetically reactive surface sites to the dissolution rate. In this study, we investigate how surface features influence the dissolution rate of synthetic CeO2 and ThO2, spent nuclear fuel analogues that approximate as closely as possible the microstructure characteristics of fuel-grade UO2 but are not sensitive to changes in oxidation state of the cation. The morphology of grain boundaries (natural features) and surface facets (specimen preparation-induced features) was investigated during dissolution. The effects of surface polishing on dissolution rate were also investigated. We show that preferential dissolution occurs at grain boundaries, resulting in grain boundary decohesion and enhanced dissolution rates. A strong crystallographic control was exerted, with high misorientation angle grain boundaries retreating more rapidly than those with low misorientation angles, which may be due to the accommodation of defects in the grain boundary structure. The data from these simplified analogue systems support the hypothesis that grain boundaries play a role in the so-called “instant release fraction” of spent fuel, and should be carefully considered, in conjunction with other chemical effects, in safety performance assessements for the geological disposal of spent fuel. Surface facets formed during the sample annealing process also exhibited a strong crystallographic control and were found to dissolve rapidly on initial contact with dissolution medium. Defects and strain induced during sample polishing caused an overestimation of the dissolution rate, by up to 3 orders of magnitude

A Bayesian model to predict oil spill consequences of management plans in the Gulf of Mexico

A Bayesian risk analysis model, comprising of a release assessment module and an exposure assessment module for the oil transportation system in the Gulf of Mexico is described in this paper. The model is used to compute probability distributions for oil spill quantities for 160 grid cells in the Gulf of Mexico, and the volumes of that oil to reach 58 coastline segments over a user-specified planning period. In addition to historical oil spill data, the model can accept subjective information on management alternatives involving changes in the oil transportation system. For example, volumes, tugboat escorts, mechanical equipment and hull design can be altered, and user confidence can be entered concerning how changes will effect spill number and size. The release assessment module uses a predictive Bayesian negative binomial distribution for spill number, and a predictive Bayesian distribution based on the Pareto I distribution for spill size. Conditional transport probabilities developed by the Minerals Management Service and the results of the release assessment module were used in the exposure assessment module. Oil spill data maintained by the U.S. Coast Guard for the years 1991-1995 were analyzed along with two basic oil transportation management scenarios

Flux Enhancement in Ultrafiltration of Bitumen Emulsions Using Tubular Polyvinyldiene Flouride Membranes

New emulsified bitumen fuels pose an extreme challenge to ultrafiltration (UF) membranes, rapidly depositing and adhering tar solids on membrane surfaces. In this paper, results of pilot tests demonstrating maintenance of permeate flux in such applications are described. Tubular polyvinyldiene fluoride (PVDF) membranes for ultrafiltration were shown to effectively remove Orimulsion®, a bitumen fuel emulsion, from water, resulting in a permeate quality less than 2.0 mg/L as volatile suspended solids, at an average permeate flux on the order of 35-310 Lph/m 2 (21-182 gpd/ft 2 ). The use of one part bentonite clay to ten parts Orimulsion® solids, by mass, was found to enhance permeate flux and improve membrane cleaning. Although additives were not necessary to obtain suitable flux rates or restore permeate flux, their use was shown to reduce membrane costs considerably. Practical methods for cleaning membranes fouled with bitumen suspensions in water, with and without the presence of filtration additives, are presented. Experimental results revealed that flux regeneration was possible. Further testing included development of an optimal cleaning schedule using a simple mathematical relationship based on pilot data

A Predictive Bayesian Dose-Response Assessment for Evaluating the Toxicity of Carbon Nanotubes Relative to Crocidolite Using a Proposed Emergent Model

Carbon Nanotubes (CNTs) are a product of the nanotechnology revolution and show great promise in industrial applications. However, their relative toxicity is still not well understood and has drawn comparison to asbestos fibers due to their size and shape. In this study, a predictive Bayesian dose-response assessment was conducted with extremely limited initial dose-response data to compare the toxicity of long-fiber CNTs with that of crocidolite, an asbestos fiber associated with human mesothelioma. In the assessment, a new, theoretically derived emergent dose-response model was used and compared with the single-hit and multistage models. The multistage and emergent DRFs were selected for toxicity assessment based on two criteria: visual fit to several datasets, and a goodness-of-fit test using an available data-rich study with crocidolite. The predictive assessment supports previous concerns that long-fiber CNTs have toxicity comparable to crocidolite in intratracheal and intraperitoneal applications. Collection of further dose-response data on these materials is strongly recommended

Field validation of cable monitoring and rating system (CMARS) laboratory model. Semi-annual report, 1 May 1979-31 December 1979

One year of research on validating the performance of the Cable Monitoring and Rating System (CMARS) is reported. The performance testing was conducted on underground 230-kV and 345-kV pipe type cable circuits owned by the New Jersey Public Service Electric and Gas Co. Laser temperature monitoring systems and a data acquisition system were installed. Software installation and development is discussed. The CMARS testing program is described. (LCL