Sökning: "atmospheric dispersion"

Visar resultat 1 - 5 av 12 uppsatser innehållade orden atmospheric dispersion.

1. 1. Validering av Ecolego för modellering i enlighet med PSA nivå 3 : Beräkning av markdeposition av radionuklider vid fiktiv svår härdskada vid Forsmarks kärnkraftverk

   Uppsats för yrkesexamina på avancerad nivå, Uppsala universitet/Tillämpad kärnfysik

   Författare :Olivia Winestedt; [2022]
   Nyckelord :PSA nivå 3; Probabilistisk säkerhetsanalys; Ecolego; GPM;

   Sammanfattning : The scope of this project is to investigate if the software Ecolego is suitable for creating models in accordance with level 3 PSA, with the goal of creating a model calculating the possible outcomes for the radiological impact at 20 km distance resulting from a fictional severe nuclear accident at the Forsmark Nuclear Power Plant. This report aims to answer the questions “What is the concentration on the ground (kBq/m2), at a distance of 20 km, 30 days and 10 years after the fictional severe nuclear accident, with and without filtered venting” and “Is Ecolego a suitable software for level 3 PSA models?” The source term for the fictional severe nuclear accident is made to resemble the actual source term from the Fukushima Daiichi accident including the radionuclides Cs-134, Cs-136, Cs-137, I-131, I-132, I-133 and Te-132. LÄS MER

3. 2. Inverse Atmospheric Dispersion Modeling in Complex Geometries

   Uppsats för yrkesexamina på avancerad nivå, Umeå universitet/Institutionen för fysik

   Författare :Charlie Pelland; [2022]
   Nyckelord :atmospheric dispersion modeling; dispersion modeling; invers dispersion modeling; atmospheric dispersion; invers atmospheric dispersion; CFD; computational fluid dynamics; radioactive release; openfoam; CRBN; dry deposition; dry deposition velocity; scavenging effect; wet deposition; optimization model; Reynolds Averaged Navier-Stokes; adjoint mode; time-dependent rain simulation; time-dependent rain; time dependent rain simulation; time dependent rain;

   Sammanfattning : In the event of a radioactive release in an urban environment the consequent response mustbe swift and precise. As soon as first responders have correct information, they can make anaccurate risk assessment. However, if the position, release rate and time of the radioactiverelease is unknown it is hard to know how the pollutant will spread. LÄS MER

4. 3. Evaluation of a stochastic model of coherent turbulent structures for atmospheric particle deposition applications

   Uppsats för yrkesexamina på avancerad nivå, Uppsala universitet/Luft-, vatten- och landskapslära

   Författare :Andreas Eriksson; [2022]
   Nyckelord :atmospheric dispersion; particle deposition; k-epsilon; RANS; lagrangian particle model; stochastic particle model; OpenFOAM; SIMPLE algorithm; ABL; atmospheric boundary layer; neutral boundary layer; coherent turbulent structures;

   Sammanfattning : In this thesis, we have evaluated a stochastic Lagrangian model for computing particle deposition rates with prospects to use for atmospheric deposition applications.  The model is one-dimensional and models the particle dynamics in the boundary layers near walls and obstacles by simulating the coherent turbulent structures and Brownian motion governing the wall-normal transport. LÄS MER

5. 4. Comparison of intensified turbulence events in the Baltic Sea

   Master-uppsats, Uppsala universitet/Institutionen för geovetenskaper

   Författare :Linnéa Hallgren; [2021]
   Nyckelord :turbulence; upper ocean; ocean mixing; parameterization;

   Sammanfattning : Turbulence is important since it affects the exchange of momentum, heat, and trace gases between the atmosphere and the ocean. However, measuring oceanic turbulence is not straightforward and that is why parameterizations that describe turbulence events are important. LÄS MER

7. 5. Kernel density estimators as a tool for atmospheric dispersion models

   Uppsats för yrkesexamina på avancerad nivå, Umeå universitet/Institutionen för fysik

   Författare :Daniel Egelrud; [2021]
   Nyckelord :Particle model; LPELLO; kernel density estimation; field of concentration; post-processing;

   Sammanfattning : Lagrangian particle models are useful for modelling pollutants in the atmosphere. They simulate the spread of pollutants by modelling trajectories of individual particles. However, to be useful, these models require a density estimate. The standard method to use has been boxcounting, but kernel density estimator (KDE) is an alternative. LÄS MER