H.L. Dodds

Bio: H.L. Dodds is an academic researcher from University of Tennessee. The author has contributed to research in topics: Criticality & Neutron transport. The author has an hindex of 6, co-authored 27 publications receiving 176 citations.

A Time-Dependent, Three-Dimensional Neutron Transport Methodology

Abstract: An improved quasi-static method is applied to the time-dependent, three-dimensional neutron transport equation with explicit representation of delayed neutrons. The relevant equations are derived, and the corresponding implementation of the method is presented. The resulting new code, which uses a three-dimensional, discrete ordinates code (TORT) to solve the static fixed-source equations, is tested using transient benchmark problems that are available in the literature. Results obtained with the new time-dependent code, named TDTORT, are in satisfactory agreement with the benchmark problem results.

Sputtering Calculations with the Discrete-Ordinates Method

Abstract: The purpose of this work is to investigate the applicability of the discrete-ordinates (S/sub N/) method to light ion sputtering problems. In particlar, the neutral particle discrete-ordinates computer code, ANISN, is used to calculate sputtering yields. No modifications to this code are necessary to treat charged particle transport. However, a cross-section processing code is needed for the generation of multigroup cross sections; these cross sections include a modification to the total macroscopic cross section to account for electronic interactions and small-scattering-angle elastic interactions. The discrete-ordinates approach enables calculation of the sputtering yield as functions of incident energy and angle and of many related quantities, such as ion reflection coefficients, angular and energy distributions of sputtering particles the behavior of beams penetrating thin foils, etc. The results of several sputtering problems as calculated with ANISN are presented.

Development of a hybrid stochastic/deterministic method for transient, three dimensional neutron transport

Abstract: This research develops an improved methodology (and corresponding code) for solving the time-dependent, 3-d Boltzmann Transport Equation with explicit representation of delayed neutrons. These improvements are incorporated in a modified version of the code TDKENO, entitled TDKENO-M. Specifically, these improvements are: (1) incorporate the improved quasistatic methodology into an existing quasistatic framework, specifically, include the flux shape derivative in the fixed source term instead of being neglected, also, compute the point kinetics parameters deterministically by their inner product definitions; (2) incorporate a hierarchy of three different integration time intervals for the numerical solution of the coupled set of ordinary differential equations, the shape function is assumed to vary linearly over the largest time interval, the second large time interval is used for determining the point kinetics parameters, finally, the smallest time step is used for solving the point kinetics equations; (3) apply TDKENO-M to benchmark problems to determine the accuracy of the method, particularly, TDKENO-M is applied to 1-D and 3-D benchmark problems to evaluate its capabilities; (4) combine input requirements into a single input file so that TDKENO-M is less cumbersome to execute; (5) develop the ability to restart a calculation at an intermediate problem time; and (6) develop a user-friendly manual for using TDKENO-M which describes in detail the input requirements as well as the output files, subroutines, modules, and the calculational flow.

Molten Salt Reactors for Burning Dismantled Weapons Fuel

Abstract: The molten salt reactor (MSR) option for burning fissile fuel from dismantled weapons is examined. It is concluded that MSRs are potentially suitable for beneficial utilization of the dismantled fuel. The MSRs have the flexibility to utilize any fissile fuel in continuous operation with no special modifications, as demonstrated in the Molten Salt Reactor Experiment, while maintaining their economy. The MSRs further require a minimum of special fuel preparation and can tolerate denaturing and dilution of the fuel. Fuel shipments can be arbitrarily small, which may reduce the risk of diversion. The MSRs have inherent safety features that make them acceptable and attractive. They can burn a fuel type completely and convert it to other fuels. The MSRs also have the potential for burning the actinides and delivering the waste in an optimal form, thus contributing to the solution of one of the major remaining problems for deployment of nuclear power.

Simulation of Hypothetical Criticality Accidents Involving Homogeneous Damp Low-Enriched UO2 Powder Systems

Abstract: This paper describes the development of a computer model for predicting the excursion characteristics of a postulated, hypothetical, criticality accident involving a homogeneous mixture of low-enri...

Sputtering Studies with the Monte Carlo Program TRIM.SP

Abstract: The Monte Carlo Program TRIM.SP (sputtering version of TRIM) was used to determine sputtering yields and energy and angular distributions of sputtered particles in physical (collisional) sputtering processes. The output is set up to distinguish between the contributions of primary and secondary knock-on atoms as caused by in- and outgoing incident ions, in order to get a better understanding of the sputtering mechanisms and to check on previous theoretical models. The influence of the interatomic potential and the inelastic energy loss model as well as the surface binding energy on the sputtering yield is investigated. Further results are sputtering yields versus incident energy and angle as well as total angular distributions of sputtered particles and energy distributions in specific solid angles for non-normal incidence. The calculated data are compared with experimental results as far as possible. From this comparison it turns out that the TRIM.SP is able to reproduce experimental results even in very special details of angular and energy distributions.

Nuclear reactor analysis

Abstract: This is cne of the r-are text books written in the discipline of Nuclear Reactor Analysis, where the author has considered the interests of both scientists and practising engineers, in addition to serving the needs of the academia. The most attractive feature of this book is a balanced treatment of theory and practice of the subject matter. The theoretical foundations of the reactor design methods are explained with simplified definitions and relevant practical illustrations. The author scans through quickly the traditional aspects of the so-called reactor physics and takes the reader through the details of the analytical aspects in a conventional manner. Hcwever, there is a definite departure from the classical method of approach in order to avoid lengthy and repetitive discussions, that are available in many standard text books on reactor physics. The chief departure fran tradition is the priority accorded to the treatment of the energy part of the problems as opposed to the spatial Dart normally devoted to by other authors . A similar unorthodox approach has been applied while dealing with the solution of the various equations by giving priority to computer oriented mrethods as opposed to the classical solutions.

Sputtering yield measurements

Abstract: The conditions for performing reproducible sputtering measurements are a well-defined ion beam with high enough current and uniform current density, a low enough vacuum and a well characterized target The different methods to determine total and differential sputtering yields, ie, the measurement of the loss of target material and the flux of sputtered atoms, are outlined All available yield data measured for different ions on different materials at normal incidence are depicted on a set of graphs and some are compared with the results of Sigmund's theory The dependence of the yields on ion-mass, energy and angle of incidence and on target structure and temperature are discussed For light ion sputtering an empirical analytical formula is given Energy reflection coefficients, also named sputtering efficiencies are discussed