Department of Nuclear Engineering and Radiation Health Physics
http://hdl.handle.net/1957/18496
Mon, 26 Jan 2015 06:28:25 GMT2015-01-26T06:28:25ZMonte Carlo derived absorbed fractions for a voxelized model of Oncorhynchus mykiss, a rainbow trout
http://hdl.handle.net/1957/53786
Monte Carlo derived absorbed fractions for a voxelized model of Oncorhynchus mykiss, a rainbow trout
Ruedig, Elizabeth; Caffrey, Emily; Hess, Catherine; Higley, Kathryn
Simple, ellipsoidal geometries have long been the standard for estimating
radiation dose rates in non-human biota (NHB). With the introduction of a regulatory
protection standard that emphasizes protection of NHB as its own endpoint, there has
been interest in improved models for the calculation of dose rates in NHB. Here we
describe the creation of a voxelized model for a rainbow trout (Oncorhynchus mykiss), a
freshwater aquatic salmonid. Absorbed fractions (AFs) for both photon and electron
sources were tabulated at electron energies of 0.1, 0.2, 0.4, 0.5, 0.7, 1.0, 1.5, 2.0, and 4.0
MeV and photon energies of 0.01, 0.015, 0.02, 0.03, 0.05, 0.1, 0.2, 0.5, 1.0, 1.5, 2.0, and
4.0 MeV. A representative set of the data is made available in this publication; the entire
set of absorbed fractions is available as electronic supplementary materials. These results
are consistent with previous voxelized models, and reinforce the well-understood
relationship between the AF and the target’s mass and location, as well as the energy of
the incident radiation.
This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: http://link.springer.com/journal/411
Fri, 01 Aug 2014 00:00:00 GMThttp://hdl.handle.net/1957/537862014-08-01T00:00:00ZWireless, Low-Cost, FPGA-based Miniature Gamma Ray Spectrometer
http://hdl.handle.net/1957/52961
Wireless, Low-Cost, FPGA-based Miniature Gamma Ray Spectrometer
Becker, E. M.; Farsoni, A. T.
A compact, low-cost, wireless gamma-ray spectrometer is a tool sought by a number of different organizations in the field of radiation detection. Such a device has applications in emergency response, battlefield assessment, and personal dosimetry. A prototype device fitting this description has been constructed in the Advanced Radiation Instrumentation Laboratory at Oregon State University. The prototype uses a CsI(Tl) scintillator coupled to a solid-state photomultiplier and a 40 MHz, 12-bit, FPGA-based digital pulse processor to measure gamma radiation, and is able to be accessed wirelessly by mobile phone. The prototype device consumes roughly 420 mW, weighs about 28 g (not including battery), and measures 2.54 x 3.81 cm². The prototype device is able to achieve 5.9% FWHM energy resolution at 662 keV.
This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/nuclear-instruments-and-methods-in-physics-research-section-a-accelerators-spectrometers-detectors-and-associated-equipment/.
Sat, 11 Oct 2014 00:00:00 GMThttp://hdl.handle.net/1957/529612014-10-11T00:00:00ZThe iterative thermal emission method: A more implicit modification of IMC
http://hdl.handle.net/1957/52839
The iterative thermal emission method: A more implicit modification of IMC
Long, A. R.; Gentile, N. A.; Palmer, T. S.
For over 40 years, the Implicit Monte Carlo (IMC) method has been used to solve
challenging problems in thermal radiative transfer. These problems typically contain
regions that are optically thick and diffusive, as a consequence of the high degree
of “pseudo-scattering” introduced to model the absorption and reemission of photons
from a tightly-coupled, radiating material. IMC has several well-known features that
could be improved: a) it can be prohibitively computationally expensive, b) it introduces
statistical noise into the material and radiation temperatures, which may be problematic in
multiphysics simulations, and c) under certain conditions, solutions can be nonphysical, in
that they violate a maximum principle, where IMC-calculated temperatures can be greater
than the maximum temperature used to drive the problem.
We have developed a variant of IMC called iterative thermal emission IMC, which is designed
to have a reduced parameter space in which the maximum principle is violated. ITE IMC is
a more implicit version of IMC in that it uses the information obtained from a series of IMC
photon histories to improve the estimate for the end of time step material temperature
during a time step. A better estimate of the end of time step material temperature
allows for a more implicit estimate of other temperature-dependent quantities: opacity,
heat capacity, Fleck factor (probability that a photon absorbed during a time step is not
reemitted) and the Planckian emission source.
We have verified the ITE IMC method against 0-D and 1-D analytic solutions and problems
from the literature. These results are compared with traditional IMC. We perform an
infinite medium stability analysis of ITE IMC and show that it is slightly more numerically
stable than traditional IMC. We find that significantly larger time steps can be used with
ITE IMC without violating the maximum principle, especially in problems with non-linear
material properties. The ITE IMC method does however yield solutions with larger variance
because each sub-step uses a different Fleck factor (even at equilibrium).
To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/journal-of-computational-physics.
Sat, 15 Nov 2014 00:00:00 GMThttp://hdl.handle.net/1957/528392014-11-15T00:00:00ZPredicting Critical Flow Velocity and Laminate Plate Collapse – Flat Plates
http://hdl.handle.net/1957/49977
Predicting Critical Flow Velocity and Laminate Plate Collapse – Flat Plates
Jensen, P.; Marcum, W. R.
The Oregon State University (OSU), Hydro Mechanical Fuel test Facility (HMFTF) is designed
to hydro-mechanically test prototypic plate type fuel. OSU’s fuel test program is a part of the
Global Threat Reduction Initiative (GTRI), formerly known as the Reduced Enrichment for
Research and Test Reactor program. One of the GTRI’s goals is to convert all civilian research,
and test reactors in the United States from highly enriched uranium (HEU) to a low enriched
uranium (LEU) fuel in an effort to reduce nuclear proliferation.
An analytical model has been developed and is described in detail which complements the
experimental work being performed by the OSU HMFTF, and advances the science of hydromechanics.
This study investigates two methods for determining the ‘critical flow velocity’ for a
laminate plate. The objective is accomplished by incorporating a flexural rigidity term into the
formulation of critical flow velocity originally derived by Donald R. Miller, and employing
sandwich structure theory to determine the rigidity term. The final outcome of this study results
in the developing of a single equation for each of three different edge boundary conditions which
reliably and comprehensively predicts the onset of plate collapse. The two models developed and
presented, are termed the monocoque analogy and the ideal laminate model. Of these two
models, the ideal laminate model is the most resolved and comprehensive in its predictions.
This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/nuclear-engineering-and-design/.
Sat, 01 Feb 2014 00:00:00 GMThttp://hdl.handle.net/1957/499772014-02-01T00:00:00Z