Impact of plastic softening of over-aged CuCrZr alloy heat sink tube on the structural reliability of a plasma-facing component

Miśkiewicz, M.; You, J.-H.

doi:10.1016/j.fusengdes.2007.06.002

Cited by 16 publications

(8 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this circumstance, the soft copper bond layer may preferentially suffer from alternating plastic straining (low cycle fatigue) [4,5]. Due to the strain-controlled loading nature progressive accumulation of plastic strains (incremental plastic collapse) will not occur [6]. Even the initially hardened CuCrZr heat sink may possibly experience such detrimental effect, when CuCrZr alloy undergoes irreversible softening caused by over-ageing [7].…”

Section: Introductionmentioning

confidence: 99%

Material parameters of copper and CuCrZr alloy for cyclic plasticity at elevated temperatures

You

Miśkiewicz

2008

Journal of Nuclear Materials

Self Cite

View full text Add to dashboard Cite

In this work material parameters of cyclic plasticity for soft copper and CuCrZr alloy were determined using the combined non-linear isotropic and kinematic hardening law (the Frederick-Armstrong-Chaboche model) for the temperature range between 20 °C and 550 °C. These parameters are the initial kinematic hardening modulus, the rate of change of kinematic hardening modulus, the maximum change in the size of the yield surface and the rate of change of the yield surface size. Both precipitation-hardened and annealing-softened states were examined for CuCrZr alloy. A series of strain-controlled cyclic tensioncompression tests were conducted at four temperature levels. The parameters were calibrated with the stabilised loops of stress-strain curves. The predicted stabilised loops from FEM simulation with the calibrated parameters showed good agreement with the experimental result demonstrating the validity of the considered constitutive model.

show abstract

Section: Introductionmentioning

confidence: 99%

Material parameters of copper and CuCrZr alloy for cyclic plasticity at elevated temperatures

You

Miśkiewicz

2008

Journal of Nuclear Materials

Self Cite

View full text Add to dashboard Cite

show abstract

“…This is achieved by imposing a uniform room temperature on the whole monoblock assembly with an assigned stress-free temperature of 470˚C (The CuCrZr precipitation hardening heat treatment temperature). This is also similar to the simulation method described by Li [15] and Miskiewicz [19].…”

Section: Structural Model and Load Cyclesmentioning

confidence: 58%

“…Furthermore, the maximum available strain (nominally 139% in the uniaxial case) is reduced by significant triaxial stress factor of 0.19 (Ktf=0. 19), and as a result total strain usage is determined to be 3.5. This suggest voids or cracks might be created even in this the unirradiated case.…”

Section: Local Ratchetingmentioning

confidence: 99%

Towards reliable design-by-analysis for divertor plasma facing components – Guidelines for inelastic assessment (part 1: Unirradiated)

Fursdon

You

2019

Fusion Engineering and Design

Self Cite

View full text Add to dashboard Cite

Guidelines are presented for the recommended method of assessing by analysis the structural integrity of divertor plasma facing components (PFCs) under high heat flux (HHF) loads. The objective is to enable analysis to provide greater supporting evidence for PFC qualification (which for ITER is currently achieved by test alone) and to provide reasonable estimates of irradiated PFC performance where component test data is limited or non-existent. Typically, PFCs comprise tungsten armour, CuCrZr heat-sink and copper interlayer. For more reliable assessment of this type of construction, two shortfalls in existing elastic analysis methods have been addressed. Firstly, the scope of assessment rules has been extended to cover armour failure (e.g. by deep cracking) and secondly the accuracy of analysis is increased by using inelastic analysis methods to address complexities created by PFC's multi-material block like construction. These complexities arise mainly from the dissimilar yield strengths and thermal expansion coefficients of the component materials. This paper details the proposed "low temperature" design code rules in the guidelines, which are based on a combination of existing inelastic code rules plus a set of methodologies devised specifically for PFC structures. The failure mechanisms of exhaustion of ductility, fast-fracture, fatigue and ratcheting are addressed, and the process of assessment is demonstrated by means of an example analysis on an ITER-like monoblock component in its unirradiated condition. In two followup papers, creep rules and methods for estimating the HHF structural integrity of an irradiated component using sparse irradiated materials data are presented. In the unirradiated condition it is shown that fatigue and armour cracking performance dominate predicted structural integrity, but when irradiated, exhaustion of ductility is expected to be more prevalent. It is argued that with these more rigorous assessment methods, a significant step has been made towards developing reliable design-by-analysis methods for predicting the expected HHF structural integrity performance of divertor PFC designs.

show abstract

“…-the tungsten armor surface temperature, with its melting limit at 3422°C, and a recrystallization temperature around 1200°C, above which a significant reduction of the strength of tungsten was observed in the heat flux tests of divertors [14], and major cracks appears on its surface; -the heat sink CuCrZr pipe maximum temperature, with a limit at 350°C, above which the material start softening/aging [15].…”

Section: Mono-block Model Geometric Parametermentioning

confidence: 99%

Limitations of transient power loads on DEMO and analysis of mitigation techniques

Maviglia¹,

Federici²,

Strohmayer

et al. 2016

Fusion Engineering and Design

View full text Add to dashboard Cite

The present European standard DEMO divertor target technology is based on a water-cooled tungsten mono-block with a copper alloy heat sink. This paper presents the assessment of the operational space of this technology under static and transient heat loads. A transient thermo-hydraulic analysis was performed using the code RACLETTE, which allowed a broad parametric scan of the target geometry and coolant conditions. The limiting factors considered were the coolant critical heat flux (CHF), and the temperature limits of the materials. The second part of the work is devoted to the study of the plasma strike point sweeping as a mitigation technique for the divertor power exhaust. The RACLETTE code was used to evaluate the impact of a large range of sweeping frequencies and amplitudes. A reduced subset of cases, which complied with the constraints, was benchmarked with a 3D FEM model. A reduction of the heat flux to the coolant, up to a factor ∼4, and lower material temperatures were found for an incident heat flux in the range (15-30)MW/m2. Finally, preliminary assessments were performed on the installed power required for the sweeping, the AC losses in the superconductors and thermal fatigue analysis. No evident show stoppers were found

show abstract

Impact of plastic softening of over-aged CuCrZr alloy heat sink tube on the structural reliability of a plasma-facing component

Cited by 16 publications

References 7 publications

Material parameters of copper and CuCrZr alloy for cyclic plasticity at elevated temperatures

Material parameters of copper and CuCrZr alloy for cyclic plasticity at elevated temperatures

Towards reliable design-by-analysis for divertor plasma facing components – Guidelines for inelastic assessment (part 1: Unirradiated)

Limitations of transient power loads on DEMO and analysis of mitigation techniques

Contact Info

Product

Resources

About