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Martin, William R

Publications and source records attributed to Martin, William R.

Progress with On-The-Fly Neutron Doppler Broadening in MCNP

The University of Michigan, ANL, and LANL have been collaborating on a US-DOE-NE University Programs project 'Implementation of On-the-Fly Doppler Broadening in MCNP5 for Multiphysics Simulation of Nuclear Reactors.' This talk describes the project and provides results from the initial implementation of On-The-Fly Doppler broadening (OTF) in MCNP and testing. The OTF methodology involves high precision fitting of Doppler broadened cross-sections over a wide temperature range (the target for reactor calculations is 250-3200K). The temperature dependent fits are then used within MCNP during the neutron transport, for OTF broadening based on cell temperatures. It is straightforward to extend this capability to cover any temperature range of interest, allowing the Monte Carlo simulation to account for a continuous distribution of temperature ranges throughout the problem geometry.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Development of Continuous-Energy Eigenvalue Sensitivity Coefficient Calculation Methods in the Shift Monte Carlo Code

Three methods for calculating continuous-energy eigenvalue sensitivity coefficients were developed and implemented into the SHIFT Monte Carlo code within the Scale code package. The methods were used for several simple test problems and were evaluated in terms of speed, accuracy, efficiency, and memory requirements. A promising new method for calculating eigenvalue sensitivity coefficients, known as the CLUTCH method, was developed and produced accurate sensitivity coefficients with figures of merit that were several orders of magnitude larger than those from existing methods.

42 ENGINEERING↗

Determining Importance Weighting Functions for Contributon Theory Eigenvalue Sensitivity Coefficient Methodologies

This study introduced three approaches for calculating the importance weighting function for Contributon and CLUTCH eigenvalue sensitivity coefficient calculations, and compared them in terms of accuracy and applicability. The necessary levels of mesh refinement and mesh convergence for obtaining accurate eigenvalue sensitivity coefficients were determined through two parametric studies, and the results of these studies suggest that a sufficiently-accurate mesh for calculating eigenvalue sensitivity coefficients can be obtained for the Contributon and CLUTCH methods with only a small increase in problem runtime.

99 GENERAL AND MISCELLANEOUS↗