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Gaithersburg, MD, United States

Grant
Agency: Cordis | Branch: FP7 | Program: CP-FP | Phase: Fission-2011-2.3.1 | Award Amount: 3.06M | Year: 2012

In a nuclear power plant, a single metallic component may be fabricated from different materials. For example, RPV components are made from ferritic steel, whereas some of the connecting pipelines are fabricated from austenitic stainless steel. As a consequence different components often need to be connected by so-called dissimilar metal welds (DMW). Despite extensive research in Euratom Framework projects such as BIMET and ADIMEW, further work is needed to quantify the structural performance of ageing DMWs. The first purpose of this project shall be to gather relevant information from field experience: typical locations of DMWs in Western as well as Eastern LWRs will be identified and their characteristics considered, as well as applicable assessment methods. Micro-mechanical modelling of ductile failure processes will be used as an innovative technique to augment current numerical methods for structural integrity assessment of DMWs. The modelling will take account of ageing related phenomena and realistic stress distributions in the weld area and be supported by a comprehensive material test program. A procedure for measuring fracture toughness in DMWs will be developed. The work will also include an assessment of Leak Before Break (LBB) behaviour. Overall the project will serve to promote common understanding of structural integrity assessment of DMWs in existing and future NPPs of EU member states. This will be the technical basis towards the development of harmonised European codes and standards for multi-metal components, which is currently not available.


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


Grant
Agency: Cordis | Branch: FP7 | Program: CP | Phase: Fission-2007-1.1-01 | Award Amount: 6.20M | Year: 2008

Main objectives of ReCosy are the sound understanding of redox phenomena controlling the long-term release/retention of radionuclides in nuclear waste disposal and providing tools to apply the results to Performance Assessment/Safety Case. Although redox is not a new geochemical problem, different questions are still not resolved and thus raised by implementers and scientists. From a top-down approach, the reliability of redox measurements for site characterization, redox disturbances by the near-field materials, changes induced by glaciation scenarios or the redox buffer capacity of host-rocks and the kinetics of response to redox perturbations are addressed. From a bottom-up approach, questions concerning the interpretation of mixed potentials, surface mediated reactions, redox states of actinides and long-lived fission products, the source term of spent nuclear fuel in the presence of corroding steel as well as the role of microbes and biofilms on the evolution of the redox state are tackled. Radionuclide redox transformations on minerals are decisive scenarios in the NEA FEP list and in the RETROCK project. In the large FP 6 IPs NF-PRO and FUNMIG, redox phenomena controlling the retention of radionuclides were addressed, although not systematically considered. The ReCosy concept is innovative in the scientific approach to the redox phenomena, including i) advanced analytical tools, ii) investigations of processes responsible for redox control iii) required data on redox controlling processes, and iv) response to disturbances in disposal systems. To this aim, the scientific-technical work program is structured along six RTD workpackages, covering near-field and far-field aspects as well as all relevant host-rocks considered in Europe. The 28 partners of ReCosy include the key European Research Institutes and Universities from 12 European countries, and Russia.

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