Predictions of convective losses from a solar cavity receiver

Convective losses arising from buoyancy driven flow were calculated for a two-dimensional model simulating a solar cavity receiver. The TEMPEST code, capable of fully three-dimensional coupled thermal-hydraulic transient calculations, was used for the simulation. Predicted velocity and temperature results for a 2.59 m deep by 2.88 m high rectangular cavity with an aperture opening of 1.72 m were used to determine convective losses for prescribed interior wall temperatures and cavity orientation. Velocity vector and temperature isotherm plots were used to analyze flow characteristics

Vitrification of noble metals containing NCAW simulant with an engineering scale melter (ESM): Campaign report

ESM has been designed as a 10th-scale model of the DWPF-type melter, currently the reference melter for nitrification of Hanford double shell tankwaste. ESM and related equipment have been integrated to the existing mockup vitrification plant VA-WAK at KfK. On June 2-July 10, 1992, a shakedown test using 2.61 m{sup 3} of NCAW (neutralized current acid waste) simulant without noble metals was performed. On July 11-Aug. 30, 1992, 14.23 m{sup 3} of the same simulant with nominal concentrations of Ru, Rh, and Pd were vitrified. Objective was to investigate the behavior of such a melter with respect to discharge of noble metals with routine glass pouring via glass overflow. Results indicate an accumulation of noble metals in the bottom area of the flat-bottomed ESM. About 65 wt% of the noble metals fed to the melter could be drained out, whereas 35 wt% accumulated in the melter, based on analysis of glass samples from glass pouring stream in to the canisters. After the melter was drained at the end of the campaign through a bottom drain valve, glass samples were taken from the residual bottom layer. The samples had significantly increased noble metals content (factor of 20-45 to target loading). They showed also a significant decrease of the specific electric resistance compared to bulk glass (factor of 10). A decrease of 10- 15% of the resistance between he power electrodes could be seen at the run end, but the total amount of noble metals accumulated was not yet sufficient enough to disturb the Joule heating of the glass tank severely

Assessment of Tank 241-C-106 temperature response indications

This report presents an assessment of waste tank 241-C-106 temperature response indications. The results are obtained through evaluation of historical data for FIC surface level data and temperature indication data from thermocouples in risers 8 and 14, contained in the SACS and TMACS databases. Computer analysis is used to augment observations and conclusions about hypothesized mechanisms present in the tank that could explain the data observations. From the historical temperature indications of risers 8 and 14 (neglecting the ventilation outages), several general observational conclusions are drawn that support hypotheses explaining more recently observed behavior

Compilation of information on melter modeling

The objective of the task described in this report is to compile information on modeling capabilities for the High-Temperature Melter and the Cold Crucible Melter and issue a modeling capabilities letter report summarizing existing modeling capabilities. The report is to include strategy recommendations for future modeling efforts to support the High Level Waste (HLW) melter development

Verification and benchmarking of MAGNUM-2D: a finite element computer code for flow and heat transfer in fractured porous media

The objective of this work is to assess prediction capabilities and features of the MAGNUM-2D computer code in relation to its intended use in the Basalt Waste Isolation Project (BWIP). This objective is accomplished through a code verification and benchmarking task. Results are documented which support correctness of prediction capabilities in areas of intended model application. 10 references, 43 figures, 11 tables

Evaluation of coarse coal hydrotransport data and predictive models

Two recently published mechanistic models and three empirical correlations were used to analyze the hydrodynamic data obtained from 7.62 cm and 15.24 cm coarse particle pipeline tests. Predicted versus measured headloss gradients were plotted as a means of evaluating the ability of each method to reproduce the parameter trends exhibited by the pressure drop data. Of the five methods selected for analyzing the data, three methods were capable of predicting the headloss gradient with some certainty. A limited parameterization of these models to investigate their sensitivity of prediction is also presented. The data used in this work were obtained with coal in an experimental program conducted by the US Bureau of Mines which sought to provide coarse particle pipeline data. In these recirculating loop tests, velocity ranges of 0.3 through 4.5 m/sec were used to pump solid concentrations of up to 45% by weight. Pressure drop data were obtained for particle to pipe diameter ranges of up to 0.25 under various flow conditions. This paper describes an evaluation of the data and the models

Sliding-bed model applied to noncircular pipe hydrotransport

A model based on a force balance analysis for sliding-bed hydrotransport in noncircular pipes is presented. Predictions of the model are compared with previously published hydrotransport data for 1.379-mm glass beads (S = 2.93). The beads were transported in rectangular pipes with aspect ratios of 0.5, 1.0, and 2.0, as well as in a 25.4-mm circular pipe. Delivered volumetric concentration ranged from 0.018 to 0.155. For equal delivered concentrations in equivalently sized pipes, the data showed that the rectangular pipe with the wide side on the bottom required less pump head than a circular pipe at a given apparent mean velocity. The developed model correctly predicts this data trend. These results demonstrate the extended versatility of the force balance approach for modeling hydrotransport phenomena

TEMPEST: A three-dimensional time-dependence computer program for hydrothermal analysis: Volume 1, Numerical methods and input instructions: Revision 2

TEMPEST offers simulation capabilities over a wide range of hydrothermal problems that are definable by input instructions. These capabilities are summarized by categories as follows: modeling capabilities; program control; and I/O control. 10 refs., 22 figs., 2 tabs. (LSP

Computer modeling of forced mixing in waste storage tanks

Numerical simulation results of fluid dynamic and physical processes in radioactive waste storage tanks are presented. Investigations include simulation of jet mixing pump induced flows intended to mix and maintain particulate material uniformly distributed throughout the liquid volume. Physical effects of solids are included in the code. These are particle size through a settling velocity and mixture properties through density and viscosity. Calculations have been accomplished for a centrally located, rotationally-oscillating, horizontally-directed jet mixing pump for two cases. One case is with low jet velocity and high settling velocity. It results in nonuniform distribution. The other case is with high jet velocity and low settling velocity. It results in uniform conditions. Results are being used to aid in experiment design and to understand mixing in the waste tanks. These results are to be used in conjunction with scaled experiments to define limits of pump operation to maintain uniformity of the mixture in the storage tanks during waste retrieval operations

Cesium capsule thermal analysis

Double-walled stainless steel capsules, produced by the Hanford Waste Encapsulation and Storage Facility (WESF), were designed to facilitate storage of radioactive cesium chloride (CsCl). The capsules were later determined to be a useful resource for irradiation facilities (IFs), and are currently being used at several commercial IFs. A capsule at one of these facilities recently failed, resulting in a release of the CsCl. A thermal analysis of a WESF capsule was performed by Pacific Northwest Laboratory (PNL) at the request of Westinghouse Hanford Company. In this analysis, parametric calculations demonstrates the impact that various parameters have on the temperature distribution within a capsule in a commercial irradiation facility. Specifically, the effect of varying the gas gap conductivity, the exterior heat sink temperatures, the exterior heat transfer distribution, the stainless steel emissivity, and the gamma heating rate were addressed. In addition, a calculation was performed to estimate the highest temperatures likely to have been encountered in one of these capsules. 8 refs., 17 figs., 4 tabs