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Gaithersburg, MD, United States

Olsson P.A.T.,Malmo University | Massih A.R.,Malmo University | Blomqvist J.,Malmo University | Alvarez Holston A.-M.,Studsvik Inc. | Bjerken C.,Malmo University
Computational Materials Science | Year: 2014

We report the results of a systematic ab initio study of the elastic and thermodynamic properties of γ-ZrH, δ-ZrH1.5,γ-ZrD, and δ-ZrD1.5. In addition, pure α-Zr as well as the ε-ZrH2 and ε-ZrD2 phases are evaluated for reference. The calculations are performed using quantum mechanical density functional theory (DFT) with the frozen core projector augmented wave (PAW) approach and a generalised gradient approximated (GGA) exchange-correlation functional. To capture the variations of the thermodynamic quantities over a wide range of temperatures (0≲T≤1000K), the quasi-harmonic approximation approach is adopted where the influence of the vibrational and electronic free energies are included by means of the phonon and electron densities of state. This allows for quantifying the contributions of the electron density of states, which were not accounted for in the previous studies. All the pertinent elastic constants and phonon properties for the considered hydride/deuteride phases are calculated and compared with experimental data; which were not done before. We have further computed the entropy, heat capacity and enthalpy as well as low temperature thermodynamic properties such as the Debye temperature and the electronic heat capacity constant for all the hydride and deuteride phases. The results of our computations concur well with the corresponding data obtained by measurements that are reported in the literature and offer the necessary data and basis for multiscale modelling of zirconium alloys. © 2014 Elsevier Ltd. All rights reserved. Source


Rachamin R.,Helmholtz Center Dresden | Rachamin R.,Ben - Gurion University of the Negev | Wemple C.,Studsvik Inc. | Fridman E.,Helmholtz Center Dresden
Annals of Nuclear Energy | Year: 2013

In this study, HELIOS-2 deterministic transport code and Serpent Monte-Carlo (MC) reactor physics code were considered as tools for preparation of few-group constants for sodium cooled fast reactor (SFR) analysis. Initially, applicability of the mainly LWR-oriented HELIOS-2 code to the modeling of SFR lattices was investigated and recommendations for methodological modifications were given. At the next stage the methodology for few-group cross section generation for fuel and non-multiplying regions of SFR core was proposed. Afterward, few-group constants produced by HELIOS-2 and Serpent employing the proposed methodology were used by nodal diffusion code DYN3D for the analysis of a reference SFR core. Finally, the DYN3D results were verified against the full core Serpent MC solution. The full core DYN3D results obtained using few-group constants produced by Serpent agreed very well with that of the reference full core MC simulations. The use of HELIOS-2 based few-group constants led to somewhat reduced agreement between reference MC and DYN3D results. The implementation of the suggested modifications to the HELIOS-2 methodology can potentially improve its modeling accuracy for SFR lattices. © 2012 Elsevier Ltd. All rights reserved. Source


COPERNICUS is the Studsvik code for performing nuclear fuel optimization over a multi-cycle planning horizon that provides for an implicit coupling between traditionally separate in-core and out-of-core fuel management decisions. These decisions include determination of: fresh fuel region size; sub-region enrichments and bundle designs; exposed fuel re-use; and core loading pattern. The COPERNICUS methodology is based on a parallel implementation of the Simulated Annealing optimization algorithm, modified by the technique of Mixing of States, that allows for deployment in a processor scalable environment. COPERNICUS utilizes the 3-D licensing grade code SIMULATE for evaluation of all core loading pattern constraints, such as those involving reactivity and thermal margin requirements. Results are presented for a transition cycle design that compares performance of multi-cycle optimization to successive, single cycle optimization with regard to reducing levelized fuel costs. © 2011 Elsevier Ltd. All rights reserved. Source


Siegel A.,Argonne National Laboratory | Smith K.,Studsvik Inc. | Smith K.,Massachusetts Institute of Technology | Fischer P.,Argonne National Laboratory | Mahadevan V.,Argonne National Laboratory
Journal of Computational Physics | Year: 2012

A domain decomposed Monte Carlo communication kernel is used to carry out performance tests to establish the feasibility of using Monte Carlo techniques for practical Light Water Reactor (LWR) core analyses. The results of the prototype code are interpreted in the context of simplified performance models which elucidate key scaling regimes of the parallel algorithm. © 2012 Elsevier Inc. Source


Bahadir T.,Studsvik Inc.
5th Topical Meeting on Advances in Nuclear Fuel Management, ANFM 2015: Advances in Nuclear Fuel Management V | Year: 2015

The recent improvements implemented in Studsvik's next generation code package CMS5, with CASM05 and SIMULATE5, in modeling the PWR radial baffle/reflector is presented in this work. The shortcomings in the conventional approach of generating radial homogenized cross-sections and discontinuity factors from a ID fuel/reflector transport calculation have been eliminated by re-computing the reflector node cross-sections and discontinuity factors in real core geometry by using the submesh calculation model in SIMULATE5. The submesh constants for the radial reflectors are generated from either a ID fuel/reflector transport calculation or a multi-assembly core transport calculation. The effects of radial reflector modeling on core eigenvalue and assembly power predictions are demonstrated for the BEAVRS benchmark problem. Source

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