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1	Monte-Carlo response for mobile gamma spectroscopy in fallout affected residential areas Lindberg, William January 2021 (has links) Historically, two nuclear power plant incidents have led to major releases of radioactive isotopes into the environment. In the unfortunate event that such an incident would occur in Sweden, the national emergency preparedness has set-up carborne detector systems which can be used to map radionuclides in fallout affected areas. However, analysing the carborne measurments is not trivial. To investigate how these detector systems behave, a full scale model of a Swedish suburban neighborhood was constructed in the particle transport code SERPENT2. Within this model, detector and car geometries where defined to obtain an estimate of the measurement one would obtain efter different cleanup scenarios with an initial 100 kBq/m^2 ground deposition of the fission product Cs-137. mobile gamma spectroscopy SERPENT2 Monte-Carlo Physical Sciences Fysik
2	Improved data analysis anduncertainty evaluation of decay heat measurements at CLAB Lindberg, William January 2019 (has links) To safely encase and store spent fuel assemblies in its final geological storage, accurate measurements of their heat output must be performed. To this end, information about the geometry and sensor set-up of the calorimeter at the interim storage facility CLAB was gathered. The data from the temperature sensors where compared to each other and an analytical expression was proposed to fit the data. A methodology for calculating calibration curves was formulated and its uncertainties were evaluated. Differences were found between the fits of measurements from differing measurement campaigns. The measurement campaigns resulted in calibration curves with notable offset from each other. The computer code SERPENT2 was used to construct a 3d geometry model of the calorimeter and the ratio of photons entering and escaping the calorimeter wall was calculated for photon energies which dominate the gamma spectrum from spent fuel assemblies of about 5 to 40 years cooling time. Natural Sciences Naturvetenskap Physical Sciences Fysik
3	Modeling The Temperature of a Calorimeter at Clab : Considering a Thermodynamic Model of The Temperature Evolution of The Calorimeter System 251 Ekman, Johannes January 2021 (has links) It is important to know the heat generated due to nuclear decay in the final repository for spent nuclear fuel. In Sweden, the heating powers generated in spent nuclear fuels are currently measured in the calorimeter System 251 at the Clab facility, Oskarshamn. In order to better measure, and increase understanding, of the temperature measurements in the calorimeter, a simple thermodynamic model of its temperature evolution was developed. The model was described as a system of ordinary differential equations, which were solved, and the solution was applied to calibration measurements of the calorimeter. How precise the model is, how its parameters affect the model, et cetera, are addressed. How the temperature evolution of the system changes as the values of parameters in the model are changed is addressed. The mass correction of the calorimeter could be estimated from this model, which validated the established mass correction of the calorimeter. How the measurement results from the calorimeter would be affected if the volume of the calorimeter was changed was also considered. Additionally, gamma radiation escape from the calorimeter without being detected as heat in the calorimeter. The gamma escape energy fraction was estimated by SERPENT simulations of the calorimeter, as a function of the initial photon energy. The gamma escape was also estimated for different values of the radius of System 251. calorimetry calorimeter System 251 temperature evolution spent nuclear fuel SNF MATLAB SERPENT2 Clab nuclear decay heat calibration measurements thermodynamic model gamma escape fraction mass correction calibration measurements electric heater three component system eigenvalues eigenvalue estimation temperature increase method sensitivity of mass correction calorimeter heat capacity mass correction uncertainty calorimeter calibration curve monoenergetic gamma spectrum Subatomic Physics Subatomär fysik Other Physics Topics Annan fysik

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