It is important for practical and legal reasons that water and sediments in disturbed areas around the mining operation should be controlled. The construction of a well-designed drainage system that controls erosion and thus restores the proper hydraulic function of the surface is one of the most important post-disturbance features which should be done as part of the mining activities. However, even with the best planning and design, unless proper construction practices are adapted; both the disturbed and reclaimed areas are very much likely to be susceptible to erosion, sedimentation and stability problems. In order to tackle the problem, guidelines on how to design and construct the drainage system should be well prepared. The main objective of this study was to prepare guidelines for the proper design, construction and monitoring of the water drainage management system in the study areas (Kankberg, Maurliden and Renström-Petiknäs). This report has analysed the results from the outcome of HEC-RAS software for the case study of the new ditch around the Maurliden mine site and integrated with different guidelines. Based on the results of the HEC-RAS, the most common problems in the drainage system have been identified. Moreover the thesis project identified important physical parameters such as cross-sections and slopes of the representative ditch which affect the function of the ditch in the study areas. Hydraulic parameters such as velocity which is very important for designing the type of lining and also Froude number which is very important in identifying the type of flow whether it is super-critical, critical or sub-critical were identified. The latter helps to select the type of guideline to be used between steep slope and mild slope.

Choking flow plays an integral part not only in the engineered safeguards of a nuclear power plant (NPP), but also to everyday operation. Current pressurized water reactor steam generators operate on the leak-before-break approach. The ability to predict and estimate a leak rate through a steam generator tube crack is an important safety parameter. Knowledge of the maximum flow rate through a crack in the steam generator tube allows the coolant inventory to be monitored accordingly. Here an assessment of the choking flow models in thermal-hydraulics code RELAP5/MOD3.3 is performed and its suitability to predict choking flow rates through small simulated cracks of steam generator tubes is evaluated based on collected experimental data. Six samples of the data were studied in this work which correspond to steam generator tube crack<br>samples 6-11. Each sample has a wall thickness, channel length (L), of 1.14 mm. Exit areas of these samples, 6-11, are 2.280E-06 m^2, 2.493E-06 m^2, 1.997E-06 m^2, 1.337E-06 m^2, and 2.492E-06. Samples 6-11 have a channel length to hydraulics diameter ratio (L/D) between 3.0-5.3. Two separate pressure differentials of 6.89 MPa and 4.13 MPa were applied across the samples with a range of subcooling from 20℃ to 80℃ and 20℃ to 60℃. Flow rates through these samples were modeled using the thermal-hydraulic system code RELAP5/MOD3.3. Simulation results are compared to experimental values and modeling techniques are discussed. It is found that both the Henry-Fauske and Ransom-Trapp models better predict choking mass flux for longer channels. <br> <br> <br>

The Oregon State University (OSU), Hydro Mechanical Fuel test Facility (HMFTF) is designed to hydro-mechanically test prototypical plate type fuel. OSU's fuel test program is a part of the Global Threat Reduction Initiative (GTRI), formerly known as the Reduced Enrichment for Research and Test Reactor program. One of the GTRI's goals is to convert all civilian research, and test reactors in the United State from highly enriched uranium (HEU) to a low enriched uranium (LEU) fuel in an effort to reduce nuclear proliferation. An analytical model has been developed and is described in detail which complements the experimental work being performed by the OSU HMFTF, and advances the science of hydro-mechanics. This study investigates two methods for determining the critical flow velocity for a pair of laminated plates. The objective is accomplished by incorporating a flexural rigidity term into the formulation of critical flow velocity originally derived by Miller, and employing sandwich structure theory to determine the rigidity term. The final outcome of this study results in the developing of a single equation for each of three different edge boundary conditions which reliably and comprehensively predicts the onset of plate collapse. The two models developed and presented, are termed the monocoque analogy and the ideal laminate model. / Graduation date: 2013

<p>Supercritical Water-cooled Reactor (SCWR) is a Generation-IV nuclear reactor design that operates on a direct energy conversion cycle above the thermodynamic critical point of water (374⁰C and 22.1 MPa), and offers higher thermal efficiency and considerable design simplification. As an essential step in the design of SCWR safety systems, the accident behaviour of the reactor is evaluated to ensure that the safety systems can achieve safe shutdown for all the design basis accidents. Unfortunately, the computational tools and computer codes that are currently employed for safety analysis have little application in the supercritical region, and faces significant challenges in simulating the transitions from subcritical to supercritical conditions.</p> <p>This thesis examines the predictive capabilities of Computational Fluid Dynamics (CFD) code STAR-CCM+ by evaluating critical flow (or choked flow) due to accidental release of coolant from supercritical fluid systems. The biggest challenge of this research is that the current version of STAR-CCM+ does not support supercritical simulations because the steam tables included in the package are only limited to the subcritical subset of the thermodynamic fluid properties.</p> <p>The research was carried out in two stages. In the first stage, the CFD code STAR-CCM+ was customized to simulate supercritical conditions by, (i) Generating updated steam tables to include subcritical and supercritical fluid properties and using more pressure and temperature points in the pseudo critical region (22 – 25 MPa, 645 -660 K) to handle the rapid changes in the fluid properties, and (ii) Implementing a multi-dimensional steam table interpolation scheme to access the fluid property data at any thermodynamic state during the simulation. In the second stage, the customized CFD code was extensively evaluated by simulating several accidental release scenarios from supercritical conditions using rounded-edge and sharp-edge nozzles and the model results were validated with experimental data. To overcome the solution stability (or convergence) issues encountered during the supercritical simulations, a fine tuning procedure was proposed that guaranteed convergence for all the case studies considered in this thesis.</p> <p>The simulation results revealed that the CFD model produced results that were in good agreement with experimental data and only about 10% prediction error was noticed for most cases considered in the thesis. Considering the sensitivity of the CFD model for upstream temperatures and pressures, these results appear to be quite reasonable. From the computational experience gained in this research , we believe that the CFD code STAR-CCM+ is a very useful tool to perform thermal hydraulic simulations for supercritical systems. However, an appropriate customization and extensive validation of the code is required before it can be exclusively used for safety analysis.</p> / Master of Applied Science (MASc)

Altered flow regimes following river regulation can result in significant changes in river bed geomorphology and subsequent negative ecological impacts caused by re-suspended sediments deposited on the riverbed. This study aimed to evaluate the consequences of implementing an ecological flow regime on sediments accumulated within the regulated river Juktån. Sediments were sampled and analysed for particle size distribution to estimate sediment stability. Flow alteration following the ecological flow regime was analysed with HEC-RAS unsteady flow simulation serving as a basis for calculations of forces acting to erode or retain deposited sediments. Additional analyses regarding critical flow were made with HEC-RAS steady flow simulation. Results show that 4 out of 15 cross-sections analysed would have the potential to erode and re-suspend sediments. The estimated average critical flow for when sediments become unstable with potential to re-suspend is 17 m3/s. The total sediment inventory of the studied reach is ~25000 ton, with ~3000-ton sediments potentially eroding into re-suspension. This is approximately 3% of river Umeälvens annual 100 000 ton suspended sediments before being regulated. Results indicate that river bed heterogeneity in river Juktån could benefit from implementing the ecological flow regime while not mobilizing such amounts of fine sediments that would cause clogging effects downstream the site of interest. The study also introduces the erosion rate equation which compares the annual erosion between two different flow regimes.

The main subject of this study is the improvement of predicative ability of previously developed mathematical model for prediction of so-called “fouling critical velocity”. Attention is devoted especially to the flue gas side fouling process on active heat transfer surfaces in tubular heat exchange tube banks installed in waste incineration process plants and also a technical – economic analysis based on obtained results. The model improvement consists among others in taking into account another forces (electrostatic, capillary etc.) haven't yet been considered, which influence the mutual contact between flue gas particles in case of sedimentation fouling or the contact between particles and heat exchanger tube walls respectively. The improved model has therefore more predicative ability to the reality of fouling process. The results are used for technical – economic analysis, which determines an optimal heat exchanger design with respect to fouling. Furthermore, the algorithm of this analysis, essential fouling mechanisms, fouled heat exchanger surface cleaning methods as well as fundamental knowledge of fouling coefficient prediction are presented, whereas the emphasis is placed on industrial tubular heat exchange equipment installed in waste incineration process plants.