Materials for future nuclear energy systems

Coated conductors formed from the high-temperature superconducting (HTS) material REBCO (REBa2Cu3O7−δ) enable energy-efficient and high-power-density delivery of electricity, making them key materials for clean energy generation, conversion, transmission and storage. Widespread application of HTS coated conductor wires requires operation at high temperatures in wide-ranging magnetic fields, as well as low-cost processing. In this Review, we investigate different processing methods and applications of HTS coated conductors, highlighting advances in laboratory-scale conductor processing and performance, and examining commercial potential. We discuss how the nanostructure of the HTS material impacts wire performance across different application regimes, and how the nanostructure and performance are related to the inherent supersaturation levels of the respective processing method. We outline approaches to decrease wire cost and improve wire performance in the critical application regime (20–40 K, >1 T magnetic field), and examine emerging and potential future applications of HTS coated conductors. High-temperature superconducting materials are finding their way into numerous energy applications. This Review discusses processing methods for the fabrication of REBCO (REBa2Cu3O7−δ) coated conductors, investigating the relation between performance and fabrication method, reviewing existing and new routes to improved performance and outlining emerging and future applications.

/pdf/processing-and-application-of-high-temperature-wjeng6trok.pdf

Processing and application of high-temperature superconducting coated conductors

The fusion power density produced in a tokamak is proportional to its magnetic field strength to the fourth power Second-generation high temperature superconductor (2G HTS) wires demonstrate remarkable engineering current density (averaged over the full wire), JE, at very high magnetic fields, driving progress in fusion and other applications The key challenge for HTS wires has been to offer an acceptable combination of high and consistent superconducting performance in high magnetic fields, high volume supply, and low price Here we report a very high and reproducible JE in practical HTS wires based on a simple YBa2Cu3O7 (YBCO) superconductor formulation with Y2O3 nanoparticles, which have been delivered in just nine months to a commercial fusion customer in the largest-volume order the HTS industry has seen to date We demonstrate a novel YBCO superconductor formulation without the c-axis correlated nano-columnar defects that are widely believed to be prerequisite for high in-field performance The simplicity of this new formulation allows robust and scalable manufacturing, providing, for the first time, large volumes of consistently high performance wire, and the economies of scale necessary to lower HTS wire prices to a level acceptable for fusion and ultimately for the widespread commercial adoption of HTS

/pdf/development-and-large-volume-production-of-extremely-high-3bfz4zt1yc.pdf

Development and large volume production of extremely high current density YBa2Cu3O7 superconducting wires for fusion.

With the first tokamak designed for full nuclear operation now well into final assembly (ITER), and a major new research tokamak starting commissioning (JT60SA), nuclear fusion is becoming a mainstream potential energy source for the future. A critical part of the viability of magnetic confinement for fusion is superconductor technology. The experience gained and lessons learned in the application of this technology to ITER and JT60SA, together with new and improved superconducting materials, is opening multiple routes to commercial fusion reactors. The objective of this roadmap is, through a series of short articles, to outline some of these routes and the materials/technologies that go with them.

Superconductors for fusion: A roadmap

Non-twisted stacks of coated conductors for magnets: Analysis of inductance and AC losses

https://iopscience.iop.org/article/10.1088/1741-4326/aad835/pdf

High temperature superconductors for fusion magnets

Performance degradation due to filament fracture of Nb3 Sn cable-in-conduit conductors (CICCs) is a critical issue in large-scale magnet designs such as ITER which is currently being constructed in the South of France. The critical current observed in most SULTAN TF CICC samples is significantly lower than expected and the voltage-current characteristic is seen to have a much broader transition from a single strand to the CICC. Moreover, most conductors exhibit the irreversible degradation due to filament fracture and strain relaxation under electromagnetic cyclic loading. With recent success in monitoring thermal strain distribution and its evolution under the electromagnetic cyclic loading from in situ measurement of critical temperature, we apply FEMCAM which includes strand filament breakage and local current sharing effects to SULTAN tested CICCs to study Nb3 Sn strain sensitivity and irreversible performance degradation. FEMCAM combines the thermal bending effect during cool down and the EM bending effect due to locally accumulating Lorentz force during magnet operation. It also includes strand filament fracture and related local current sharing for the calculation of cable n value. In this paper, we model continuous performance degradation under EM cyclic loading based on strain relaxation and the transition broadening upon cyclic loading to more » the extreme cases seen in SULTAN test data to better quantify conductor performance degradation. « less

/pdf/femcam-analysis-of-sultan-test-results-for-iter-nb3sn-cable-1n263fqovj.pdf

Yuhu Zhai

Papers

High temperature superconductors for fusion magnets

FEMCAM Analysis of SULTAN Test Results for ITER Nb3SN Cable-conduit Conductors