The structure of fuel element codes

Laßmann, K.

doi:10.1016/0029-5493(80)90221-6

Cited by 36 publications

(13 citation statements)

References 12 publications

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“…A higher accuracy can be obtained for a limited number of cases by fitting the model parameters to the experimental data, which nevertheless would not improve the confidence in the predictions if the model is applied to different fuel designs or irradiation conditions. Incidentally, limiting the complexity of submodels implemented in fuel performance codes preserves internal code consistency, considering the simplifications and uncertainties involved in engineeringscale fuel modeling [11]. On the other hand, a better characterization of the parameters through experimental and theoretical research may reduce the uncertainty in fission gas behavior calculations and in the multiple related aspects of fuel performance analysis.…”

Section: Discussionmentioning

confidence: 97%

“…Modeling of fission gas release and swelling as part of a global engineering-scale fuel thermo-mechanical analysis [2,11] is considered. The aim of the work is to provide an initial quantitative assessment of the uncertainty in fission gas behavior predictions with the parameter characterization presently available, as well as to identify the most important sources of results variability.…”

Section: Introductionmentioning

confidence: 99%

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Uncertainty and sensitivity analysis of fission gas behavior in engineering-scale fuel modeling

Pastore

Swiler

Hales

et al. 2015

Journal of Nuclear Materials

113

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The role of uncertainties in fission gas behavior calculations as part of engineering-scale nuclear fuel modeling is investigated using the BISON fuel performance code with a recently implemented physics based model for fission gas release and swelling. Through the integration of BISON with the DAKOTA software, a sensitivity analysis of the results to selected model parameters is carried out based on UO2 single pellet simulations covering different power regimes. The parameters are varied within ranges representative of the relative uncertainties and consistent with the information in the open literature. The study leads to an initial quantitative assessment of the uncertainty in fission gas behavior predictions with the parameter characterization presently available. Also, the relative importance of the single parameters is evaluated. Moreover, a sensitivity analysis is carried out based on simulations of a fuel rod irradiation experiment, pointing out a significant impact of the considered uncertainties on the calculated fission gas release and cladding diametral strain. The results of the study indicate that the commonly accepted deviation between calculated and measured fission gas release by a factor of 2 approximately corresponds to the inherent modeling uncertainty at high fission gas release. Nevertheless, significantly higher deviations may be expected for values around 10% and lower. Implications are discussed in terms of directions of research for the improved modeling of fission gas behavior for engineering purposes

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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Uncertainty and sensitivity analysis of fission gas behavior in engineering-scale fuel modeling

Pastore

Swiler

Hales

et al. 2015

Journal of Nuclear Materials

113

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“…The numerous material and behavioral models that represent the engineering level multi-material/multi-domain complex interaction in the fuel rod are shown in Figure 1. 9 These form the internal capability of a fuel behavior code and are generally characterized as "point models" (i.e., they describe material behavior over a representative infinitesimal, or finite but small, volume, and are therefore independent of the numerical or computational structure of the fuel performance code in which they reside). Despite the progress made in recent years in our understanding of the various physical phenomena governing LWR fuel behavior, some fundamental issues in the modeling of fuel rods behavior remain.…”

Section: Integration Pointmentioning

confidence: 99%

Light water reactor fuel performance modeling and multi-dimensional simulation

Rashid¹,

Yagnik

Montgomery

2011

JOM

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How would you……describe the overall significance of this paper? This paper describes the analytical modeling and simulation of light water reactor fuel behavior. This technology emphasizes highly detailed large-scale threedimensional computation and introduces to the traditional engineering-scale simulation the higher-order meso-scale and atomistic-scale modeling and simulation.…describe this work to a materials science and engineering professional with no experience in your technical specialty? The modeling of nuclear fuel systems involves complex physical phenomena that operate over time and geometric scales that vary by many orders of magnitude. These phenomena involve temporally and spatially dependent interactions between several material constituents that include ceramic UO 2 fuel, metallic cladding and two-phase water coolant, and take place under continuously changing irradiation and temperature conditions. The behavior of this system is simulated in multi-dimensional computer codes that constitute analytical analogs for the nuclear reactor core as a whole.…describe this work to a layperson? This paper describes the complex behavior of a nuclear reactor fuel system, which is composed of thousands of fuel rods, assembled in precise patterns and immersed in water in a pressure vessel. A typical fuel rod is a thin-walled metal tube, that contains several hundred uranium oxide pellets which generate heat through the nuclear fission process that takes place in a precisely controlled manner. The heat is transferred to the surrounding water in the vessel and is subsequently converted to mechanical energy and ultimately to electricity generation.Light water reactor fuel is a multicomponent system required to produce thermal energy through the fission process, efficiently transfer the thermal energy to the coolant system, and provide a barrier to fission product release by maintaining structural integrity. The operating conditions within a reactor induce complex multi-physics phenomena that occur over time scales ranging from less than a microsecond to years and act over distances ranging from inter-atomic spacing to meters. These conditions impose challenging and unique modeling, simulation, and verification data requirements in order to accurately determine the state of the fuel during its lifetime in the reactor. The capabilities and limitations of the current engineering-scale one-dimensional and two-dimensional fuel performance codes is discussed and the challenges of employing higher level fidelity atomistic modeling techniques such as molecular dynamics and phase-field simulations is presented.

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“…On the one hand, extending the application range of a fuel performance code originally developed for steady-state conditions to accident conditions requires modifications to the basic equations in the thermal-mechanical description of the fuel rod behaviour [2], stable numerical algorithms and a proper time step control, in addition to the implementation of specific models dealing with the high temperature behaviour of cladding such as observed under LOCA conditions [3]. For dealing with RIA events, one should check carefully the thermal expansion model because of the edge-peaked power distribution, as well as the other models affecting the effective cold gap width [4], as well as the model for thermal heat transfer in the plenum.…”

Section: Introductionmentioning

confidence: 99%