Techno-economic study of output-flexible light water nuclear reactor systems with cryogenic energy storage

This study explores whether a nuclear power plant can be combined with a cryogenic energy storage plant to allow the resultant facility to provide variable power to the grid. The study expands on previous literature by performing novel market-led system optimisation to best design the output profile of the plant to improve economic performance in the UK electricity grid. There are three key conclusions that emerge from this study. The current UK electricity market favours plant designs with rapid discharge rate. Provided that the capital cost expectations of the NuScale SMR are realised, strike prices of £55/MWh are sufficient to ensure a return on investment. However, the case for storage remains weak and only becomes viable in extreme spot market conditions

Electrical transport properties of bulk MgB2 materials synthesized by the electrolysis on fused mixtures of MgCl2, NaCl, KCl and MgB2O4

Electrolysis was carried out on fused mixtures of MgCl2, NaCl, KCl and MgB2O4 under an Ar flow at 600C. Electrical resistivity measurements for the grown deposits show an onset of superconducting transition at 37 K in the absence of applied magnetic field. The resistivity decreases down to zero below 32 K. From an applied-field dependence of resistivity, an upper critical field and a coherence length were calculated to be 9.7 T and 5.9 nm at 0 K, respectively

Application of Percolation Theory to Current Transfer in Granular Superconductors

We investigate the description of current transfer in polycrystalline superconductors by percolation theory and its limitations. Various computer models that have been proposed are reviewed and related to the experimental and theoretical framework. While some conductor properties can be well described by percolation theory and models, we argue that a conceptual gap exists between experiment and theory. This gap has to be bridged by finding relations between electromagnetic and statistical parameters. We derive various such relations and compare them with recent simulation data. In particular, we suggest a new scaling law between the two fundamental variables current and probability.Comment: submitted to European Physical Journal B, April 2002, 18 pages revised and re-submitted June 2002; added remarks and references [15-18] on Correlated Percolation; corrected minor errors; updated some reference

Effect of aromatic hydrocarbon addition on in situ powder-in-tube processed MgB2 tapes

We fabricated in situ powder-in-tube processed MgB2/Fe tapes using aromatic hydrocarbon of benzene, naphthalene, and thiophene as additives, and investigated the superconducting properties. We found that these aromatic hydrocarbons were very effective for increasing the Jc values. The Jc values of 20mol% benzene-added tapes reached 130A/mm2 at 4.2K and 10T. This value was almost comparable to that of 10mol% SiC-added tapes and about four times higher than that of tapes with no additions. Microstructure analyses suggest that this Jc enhancement is due to both the substitution of carbon for boron in MgB2 and the smaller MgB2 grain size.Comment: 6 pages, 4 figure

Improved Current Densities in MgB2 By Liquid-Assisted Sintering

Polycrystalline MgB2 samples with GaN additions were prepared by reaction of Mg, B, and GaN powders. The presence of Ga leads to a low melting eutectic phase which allowed liquid phase sintering and produces plate-like grains. For low-level GaN additions (5% at. % or less), the critical transition temperature, Tc, remained unchanged and in 1T magnetic field, the critical current density, Jc was enhanced by a factor of 2 and 10, for temperatures of \~5K and 20K, respectively. The values obtained are approaching those of hot isostatically pressed samples.Comment: 12 pages, 1 table, 4 figures, accepted in Applied Physics Letter

Transport critical current of Solenoidal MgB2/Cu Coils Fabricated Using a Wind-Reaction In-situ Technique

In this letter, we report the results of transport Jc of solenoid coils upto 100 turns fabricated with Cu-sheathed MgB2 wires using a wind-reaction in-situ technique. Despite the low density of single core and some reaction between Mg and Cu-sheath, our results demonstrate the decrease in transport Jc with increasing length of MgB2 wires is insignificant. Solenoid coils with diameter as small as 10 mm can be readily fabricated using a wind-reaction in-situ technique. The Jc of coils is essentially the same as in the form of straight wires. A Jc of 133,000 A/cm2 and 125,000 A/cm2 at 4 K and self field has been achieved for a small coil wound using Cu-sheathed tape and Cu-sheathed wire respectively. These results indicate that the MgB2 wires have a great potential for lage scale applicationsComment: 6 pages, 4 figures, 1 tabl

Cross-field demagnetization of stacks of tapes: 3D modeling and measurements

Abstract: Stacks of superconducting (SC) tapes can trap much higher magnetic fields than conventional magnets. This makes them very promising for motors and generators. However, ripple magnetic fields in these machines present a cross-field component that demagnetizes the stacks. At present, there is no quantitative agreement between measurements and modeling of cross-field demagnetization, mainly due to the need for a 3D model that takes the end effects and real micron-thick SC layer into account. This article presents 3D modeling and measurements of cross-field demagnetization in stacks of up to 5 tapes and initial magnetization modeling of stacks of up to 15 tapes. 3D modeling of the cross-field demagnetization explicitly shows that the critical current density, Jc, in the direction perpendicular to the tape surface does not play a role in cross-field demagnetization. When taking the measured anisotropic magnetic field dependence of Jc into account, 3D calculations agree with measurements with less than a 4% deviation, while the error of 2D modeling is much higher. Then, our 3D numerical methods can realistically predict cross-field demagnetization. Due to the force-free configuration of part of the current density, J, in the stack, better agreement with experiments will probably require measuring the Jc anisotropy for the whole solid angle range, including J parallel to the magnetic field

High transport currents in mechanically reinforced MgB2 wires

We prepared and characterized monofilamentary MgB2 wires with a mechanically reinforced composite sheath of Ta(Nb)/Cu/steel, which leads to dense filaments and correspondingly high transport currents up to Jc = 10^5 A/cm^2 at 4.2 K, self field. The reproducibility of the measured transport currents was excellent and not depending on the wire diameter. Using different precursors, commercial reacted powder or an unreacted Mg/B powder mixture, a strong influence on the pinning behaviour and the irreversibility field was observed. The critical transport current density showed a nearly linear temperature dependency for all wires being still 52 kA/cm^2 at 20 K and 23 kA/cm^2 at 30 K. Detailed data for Jc(B,T) and Tc(B) were measured.Comment: 21 pages, 13 figures, revised version, to be published in Supercond. Sci. Techno