2 ms·
Yes, niobium is the other problem. I think steel makers are used to adding alloying elements, but not set up for excluding them to ppm levels. I saw someone b
by pfdietz 2y ago
Yes, niobium is the other problem. I think steel makers are used to adding alloying elements, but not set up for excluding them to ppm levels. I saw someone bemoaning that the steel alone for DEMO would cost 3 billion euros (or dollars?), and I've wondered if this is the reason.
https://scipub.euro-fusion.org/wp-content/uploads/eurofusion/WPPMICPR18_19392_submitted-4.pdf https://scipub.euro-fusion.org/wp-content/uploads/eurofusion...
"[...] in the first
layer, nearest the plasma, the rate of production of 94Nb – via neutron capture (n,γ)
reactions on the stable 93Nb of niobium – is so high that Eurofer in this region is
predicted to exceed the France-LLW limit within the first year of operation, and
consequently would not be disposable as LLW under French regulations for more than
1000 years."
It's not just the steel. Beryllium typically contains about 100 ppm U, and an estimate of the cost of purifying it enough to avoid excessive fission products was another billion.
- chasil 2y agoIt will likely be necessary to start with steel made before atmospheric nuclear tests began. There are many uses for such steel already. https://en.m.wikipedia.org/wiki/Low-background_steel https://en.m.wikipedia.org/wiki/Low-background_steel
- pfdietz 2y agoI don't think that would make any difference. The problem isn't traces of radioisotopes in the initial steel, the problem is vastly larger amounts of radioisotopes created in the steel under intense neutron bombardment due to absorption in certain stable impurity elements.
- pfdietz 2y agoAnd when I say "intense", I mean it: the integrated neutron flux the first wall of a DT fusion reactor would be exposed to over its operational lifespan is comparable to, or even greater than, that experienced by components of a nuclear weapon in the brief interval of a nuclear explosion.