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Boyne A.,Ohio State University | Shen C.,General Electric | Najafabadi R.,Knolls Atomic Power Laboratory | Wang Y.,Ohio State University
Journal of Nuclear Materials | Year: 2013

A phase field model is developed to simulate interactions between gliding dislocations and irradiation induced damage loops (i.e., vacancy and self-interstitial loops) in Zirconium. Pinning contact interactions and long-range elastic interactions are simulated, with populations of defects generated based on experimental observations of typical damage microstructures in irradiated Zr. The model is employed to simulate irradiation hardening as a function of damage loop density. We find that the stress fields of damage loops contribute significantly to their effective obstacle strength, and that the elastic interactions cause the dependence of critical resolved shear stress on damage loop number density to deviate from analytical predictions of dispersed barrier hardening. The simulation predictions of the yield strength agree well with experimental measurements for different damage loop densities.© 2013 Elsevier Ltd. All rights reserved.

This paper presents the results of numerical simulations of fatigue crack growth performed using three-dimensional elastic-plastic finite element analysis. A simple node release scheme is used to simulate crack advancement. The crack front is assumed to be straight. Crack growth following a tensile overload is simulated. The total energy dissipated per cycle is calculated directly from the finite element analysis and used to predict fatigue crack growth. For comparison, fatigue crack growth rate experiments were performed on Type 304 stainless steel C(T) specimens to determine the effect of a single tensile overload. The dissipated energy per cycle is found to correlate well with the measured fatigue crack growth rate following an overload. © 2011 Elsevier Ltd.

Caro E.,Knolls Atomic Power Laboratory
Annals of Nuclear Energy | Year: 2016

MC21 is a continuous-energy Monte Carlo radiation transport code for the calculation of the steady-state spatial distributions of reaction rates in three-dimensional models. The code supports neutron and photon transport in fixed source problems, as well as iterated-fission source (eigenvalue) neutron problems. The capability to simulate the production of photon-induced neutrons has been added to the code. In this paper, relativistic two-body kinematics are used to derive exact expressions for the secondary energy and angle distribution of photoneutrons. This treatment, implemented in MC21, is important in cases where the evaluated photonuclear data does not give an explicit energy distribution. Comparisons of the relativistic relations were made to approximations in MCNP5 and TRIPOLI-4, highlighting the magnitude of the error of those approximations. © 2016 Elsevier Ltd

Ramsey S.,Fred Hutchinson Cancer Research Center | Blough D.,Knolls Atomic Power Laboratory | Kirchhoff A.,University of Utah | Kreizenbeck K.,Hutchinson Institute for Cancer Outcomes Research | And 5 more authors.
Health Affairs | Year: 2013

Much has been written about the relationship between high medical expenses and the likelihood of filing for bankruptcy, but the relationship between receiving a cancer diagnosis and filing for bankruptcy is less well understood. We estimated the incidence and relative risk of bankruptcy for people age twenty-one or older diagnosed with cancer compared to people the same age without cancer by conducting a retrospective cohort analysis that used a variety of medical, personal, legal, and bankruptcy sources covering the Western District of Washington State in US Bankruptcy Court for the period 1995-2009. We found that cancer patients were 2.65 times more likely to go bankrupt than people without cancer. Younger cancer patients had 2-5 times higher rates of bankruptcy than cancer patients age sixty-five or older, which indicates that Medicare and Social Security may mitigate bankruptcy risk for the older group. The findings suggest that employers and governments may have a policy role to play in creating programs and incentives that could help people cover expenses in the first year following a cancer diagnosis. © 2013 Project HOPE-The People-to-People Health Foundation, Inc.

Romano P.K.,Knolls Atomic Power Laboratory
Computer Physics Communications | Year: 2014

An algorithm for generating random variates from the Madland-Nix fission energy spectrum assuming a constant compound nucleus cross section is given based on physics considerations. A program was written to generate variates using the algorithm developed, and it was shown that the generated variates match the probability density function. This algorithm can be used by Monte Carlo particle transport codes to sample secondary energies for neutrons born from fission when the underlying data is given as parameters to a Madland-Nix energy spectrum. © 2014 Elsevier B.V.

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