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ukaea / PROCESS

PROCESS is a systems code at UKAEA that calculates in a self-consistent manner the parameters of a fusion power plant with a specified performance, ensuring that its operating limits are not violated, and with the option to optimise to a given function of these parameters.
https://ukaea.github.io/PROCESS/
MIT License
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New superconductor results (DEMO TF React and Wind Conductor) #798

Closed jonmaddock closed 1 week ago

jonmaddock commented 5 years ago

In GitLab by @mkovari on Mar 5, 2019, 11:00

Kamil Sedlak et al of the Swiss Plasma Centre (EPFL-SPC) have proposed using React and Wind cable for DEMO.

DC Test Results of the DEMO TF React and Wind Conductor Prototype No. 2 and
Test Results of the DEMO TF React&Wind Conductor Prototype no. 2

The DC performance of preloaded RW2 conductor is very good.
Effective strain, eeff = -0.27%.
Current-sharing temperature (Tcs) performance during load cycling and WUCDs remains stable within 0.1 K.

Extrapolation to DEMO TF Operating Conditions:
Tcs = 7.16 K at 12.23 T, 63.3 kA.

Under ITER TF operating conditions the Tcs is better (=7.4 K compared to ITER conductors 5.9-6.5 K), with much lower Nb3Sn cross section (132 mm2 versus 235 mm2 for ITER conductor).

It would be easy for us to run DEMO baselines with the lower value of effective strain given above. We should then check that the code gives the correct temperature margin for the cable described in the paper.

Any comments from @jmorris-uk @stuartmuldrew @fmavig @msiccini @schislet ?

jonmaddock commented 4 years ago

In GitLab by @schislet on Jan 6, 2020, 10:26

As it stands I don't think the code would yield the same temperature margins. We would have to include a factor increase in the Nb3Sn critical current subroutine for the R&W cables, as they have a much higher current density (at zero strain) than ITER cables do.

The physical reason for this is that during manufacture of the ITER cables, the difference in the thermal expansion of the jacket and the strands during heat treatment to produce the Nb3Sn induces such a strain on the outer strands as to cause superconductor filament fracture - effectively reducing the superconducting cross-section/ superconductor ratio of the bulk cable. This doesn't happen with R&W cables as the jacket is put on after the heat treatment. (See paper below)

We'll also have to rewrite/improve the temperature margin calculation as it doesn't work particularly well for WST Nb3Sn.

R_W_for_ITER.pdf

A few more papers about EPFL-SPC's R&W cables:

R_W_1_design.pdf

R_W_1_R_D.pdf

R_W_2.pdf

mkovari commented 1 week ago

While the React and Wind option certainly seems attractive for Nb3Sn, I don't think there is much point in creating new superconductor options right now. If in the future someone wants to create a new DEMO with improved superconductor it wouldn't be hard to do so.