Use of hybrid methods for neutron transport and sensitivity analysisKos, Bor (Avtor) Kodeli, Ivan Aleksander (Mentor) hybrid transportvariance reductionnuclear datasensitivityuncertaintyshieldingfusionfissiontotal Monte Carlo (TMC)MCNPADVANTGDenovoSUSD3DSANDYAccurate and efficient determination of uncertainties of physical quantities is a necessary step of any experiment or computational analysis. Uncertainties in particle transport simulations can be divided by type, statistical or systematic, and by origin i.e. uncertainties in nuclear data and uncertainties originating from approximations. Specifically in neutron transport simulations of fusion and fission shielding applications the approximations can be attributed to geometry and material specification, numerical (discretization of the phase space) approximations of deterministic transport methods and statistical uncertainty of stochastic transport methods. Accurate knowledge of all uncertainties related to transport simulations leads to reduced safety margins and consequently to more efficient experimental and commercial designs. The thesis is focused on developing new methods for efficient propagation of nuclear data uncertainties and reducing the statistical uncertainties of stochastic transport methods with hybrid transport methodologies. The first chapter of the thesis gives an overview of all theoretical aspects of neutron transport, variance reduction, hybrid methodologies and nuclear data (ND) sensitivity and uncertainty (SU) quantifications. The second chapter contains the description and evaluation of computer codes used in the thesis. An extensive evaluation and validation of the ADVANTG hybrid code is presented in this part. Besides the deterministic approach to ND uncertainty quantification the stochastic approach is also evaluated and used for validation purposes. In the last chapter the main contributions to the scientific field by the thesis author are presented. A large emphasis is given to the work that was done to develop a user friendly and efficient code system ASUSD (ADVANTG + SUSD3D) for ND S/U quantification. The code system enables ND S/U analysis of complex shielding experiments which was previously cumbersome, computationally expensive or even impossible. The ASUSD code system was validated and applied to two complex fusion experiments including the challenging nexp streaming benchmark experiment. Moreover ASUSD was used to asses the effect of self-shielded cross sections on the effectiveness of variance reduction parameters. The final contribution to the scientific field of hybrid particle transport is the development of a new method for determining variance reduction parameters based on sensitivity profiles - saber. SABER preforms similarly or better than the current established methodologies.20202020-02-26 07:45:04Doktorsko delo/naloga114388VisID: 106357COBISS_ID: 3411300sl