LIFE-II — A computer analysis of fast-reactor fuel-element behavior as a function of reactor operating history

Jankus, V.Z.; Weeks, R.W.

doi:10.1016/0029-5493(72)90038-6

Cited by 54 publications

(16 citation statements)

References 4 publications

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“…Once the fuel pin temperature field is known, the temperature-dependent stress-strain relations can be incorporated. 1 We will introduce the basic factors required for the fuel-pin stress analysis, including some aspects of material behavior, in this chapter, but a more detailed discussion of materials properties will be delayed for Chapter 11. Emphasis in this chapter will be placed on the behavior of mixed-oxide fuel since this is the fuel used in most SFR systems. Certain aspects of other fuels are discussed in Chapter 11.…”

Section: Fuel Pin Design Considerationsmentioning

confidence: 99%

“…Each sequence selected to cover these tightly coupled processes will inherently suffer from the need for input from processes not yet discussed. In actual design practice, all of the governing processes are integrated in large time-dependent pin analysis codes such as LIFE [1].Our presentation will begin with the geometrical arrangement of the various sections of a fuel pin, including the function of each section. We will then extend the discussion of pin geometry to the selection of pin diameter.…”

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confidence: 99%

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Fuel Pin and Assembly Design

Waltar

Todd²

2011

Fast Spectrum Reactors

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This chapter deals with the mechanical designs of fuel pins and assemblies. These core components must be designed to withstand the high temperature, high flux environment of a fast spectrum reactor for a long irradiation exposure time. In this chapter we will describe many of the factors that influence this design, and we will examine in some detail the stress analysis of the fuel pin.We begin in Section 8.2 with the basic geometric and heat transfer relationships for the fuel pin, and then discuss some topics related to fuel and fission gas that must be considered in analysis of steady-state fuel-pin performance. The discussion of fuel-pin design is continued in Section 8.3, in which failure criteria and stress analysis are presented. Discussion is then shifted in Section 8.4 to grouping the pins into a fuel assembly. This will include discussion of mechanical design problems such as fuel-pin spacing and duct swelling. Limited attention is then directed to the design of other assemblies, including blanket, control and shielding assemblies. The final section of the chapter will provide a description of methods to restrain the assemblies and to control duct bowing. Fuel Pin Design ConsiderationsFuel pin design is a complex process that involves an integration of a wide range of phenomena. The design procedure must integrate the thermal analysis of the pin with an assessment of the characteristics of the fuel and cladding as a function of temperature and irradiation history and with the stress analysis of the fuel-cladding system. Many of the phenomena that affect fuel pin performance are illustrated schematically in Fig. 8.1. Each of these will be treated in Chapters 8 and 9, with additional discussions in Chapter 11. It should be readily apparent that there is no single way to order the examination of so many interacting phenomena. Each sequence selected to cover these tightly coupled processes will inherently suffer from the need for input from processes not yet discussed. In actual design practice, all of the governing processes are integrated in large time-dependent pin analysis codes such as LIFE [1].Our presentation will begin with the geometrical arrangement of the various sections of a fuel pin, including the function of each section. We will then extend the discussion of pin geometry to the selection of pin diameter. This will involve the concept of linear power. Fuel restructuring is then introduced, followed by fission gas release and the associated length of the gas plenum to establish A. Waltar (B) Pacific Northwest

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Section: Fuel Pin Design Considerationsmentioning

confidence: 99%

mentioning

confidence: 99%

Fuel Pin and Assembly Design

Waltar

Todd²

2011

Fast Spectrum Reactors

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“…This has already been demonstrated by the generation of maps for U02 and UO2-PUO2 [13] that are based on experimental data (including in-pile creep effects) rather than theoretically derived rate equations. Combinations of the information output of deformation maps and the reactor-modeling .programs already developed [23] should provide a much more satisfying prediction of mechanical properties of nuclear materials than currently exists.…”

Section: T-^ (S-o3mentioning

confidence: 99%

Deformation Mechanism Maps — A Review with Applications

Notis

1975

Deformation of Ceramic Materials

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Deformation mechanism mapping has recently evolved as a method for quantitatively expressing complex deformation equations while at the same time allowing visual insight into our understanding of these deformation processes. Techniques for the generation of deformation mechanism maps are described, specific applications in the literature to date are reviewed, and some applications not previously considered are presented. These include the examination of sequential dependent deformation processes, grain boundary sliding, and the use of deformation mechanism maps to interpret pressure-sintering kinetics.

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“…Two different implementations of the material modification can be made: the material is treated as isotropic but with modified material properties or by replacing the material law with an anisotropic material model. The isotropic case proposed by Jankus and Weeks [32] was to consider an isotropic material where both the Young's modulus and the Poisson's ratio of the cracked material have been changed assuming the cracks were perpendicular to the fuel axis. The modified Young's modulus ( c E ) and Poisson's ratio ( c Q ) can be found from equations 2.5 and 2.6 where N is the number of cracks.…”

Section: Pellet Fracture Modelmentioning

confidence: 99%

Axisymmetric whole pin life modelling of advanced gas-cooled reactor nuclear fuel

Mella

Wenman

2013

Journal of Nuclear Materials

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Thermo-mechanical contributions to pellet-clad interaction (PCI) in advanced gas-cooled reactors (AGR) are modelled in the ABAQUS finite element (FE) code. User supplied subroutines permit the modelling of the non-linear behaviour of AGR fuel through life. Through utilization of ABAQUS's well-developed pre-and post-processing ability, the behaviour of the axially constrained steel clad fuel was modelled. The 2D axisymmetric model includes thermomechanical behaviour of the fuel with time and condition dependent material properties. Pellet cladding gap dynamics and thermal behaviour are also modelled. The model treats heat up as a fully coupled temperature-displacement study. Dwell time and direct power cycling was applied to model the impact of online refuelling, a key feature of the AGR. The model includes the viscoplastic behaviour of the fuel under the stress and irradiation conditions within an AGR core and a non-linear heat transfer model. A multiscale fission gas release model is applied to compute pin pressure; this model is coupled to the PCI gap model through an explicit fission gas inventory code. Whole pin, whole life, models are able to show the impact of the fuel on all segments of cladding including weld end caps and cladding pellet locking mechanisms (unique to AGR fuel). The development of this model in a commercial FE package shows that the development of a potentially verified and future-proof fuel performance code can be created and used. Keywords: Fuel Performance, ABAQUS, Finite Element, AGR Introduction Pellet-cladding interactionNumerous authors have investigated the phenomenon of PCI in the past [1][2][3][4][5][6][7][8][9][10]. These studies have included the AGR system. The AGR studies from the early 90s offer insight into the effective bonding forces between AGR cladding and fuel, albeit that these studies were for a very simplified geometry and material properties. Walker's models were two dimension r-T segments of a pellet and cladding in a coupled thermo-mechanical transient analysis. This analysis showed that the expected bond between pellet and clad will fail and cause the debonding of about 6% of the pellet-clad surface producing sufficient stress relief to prevent further debonding. Walker also shows that a failure of this size was sufficient to cause a two orders of magnitude reduction in the number of pellet cracks to propagate in the adjacent cladding. Most work in recent years has focussed on water cooled systems [2][3][11][12][13]. Marchal [11] showed through 3D modelling of PCI, in the CAST3M FE code, that the while pellet fracture did produce stress concentrations in the cladding there was also a significant stress remaining in the fuel fragment. These pellet fragments had sufficient remaining stresses that later interaction with the cladding through friction contact produced further radial cracking. Marchal's smeared crack model emphasises the non-linear behaviour of PCI cracking and that it is strongly dependent on fuel-cladding friction. *Manuscript Click here ...

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LIFE-II — A computer analysis of fast-reactor fuel-element behavior as a function of reactor operating history

Cited by 54 publications

References 4 publications

Fuel Pin and Assembly Design

Fuel Pin and Assembly Design

Deformation Mechanism Maps — A Review with Applications

Axisymmetric whole pin life modelling of advanced gas-cooled reactor nuclear fuel

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