Europe needs hyperscalers (lots of them) [LWN.net]

Europe needs hyperscalers (lots of them)

Posted Feb 12, 2026 14:59 UTC (Thu) by malmedal (subscriber, #56172)
In reply to: Europe needs hyperscalers (lots of them) by Wol
Parent article: FOSS in times of war, scarcity, and AI

> seems an obvious way to me to reduce costs

These things have been tried, they are not cheap. The reason they(I think France got the furthest) tried was to have the technology ready for when the uranium mines ran dry, not because it would immediately save money.

To run a reactor efficiently and safely you need to know exactly what the fuel is made of down to at least cubic decimeter resolution.

For instance Xenon-135 is a neutron absorber produced by nuclear reactions, when this builds up you need to increase neutron flux to compensate, however being a gas it can escape quickly if it gets the chance, so if the operators make a mistake the reactor can overheat and melt down.
(This is likely a major reason for Chernobyl)

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Europe needs hyperscalers (lots of them)

Posted Feb 12, 2026 15:38 UTC (Thu) by Wol (subscriber, #4433) [Link] (1 responses)

Don't remember the technology - was it AGR? I remember our AGR reactor technology got overwhelmed by the American PWR reactors, despite being much safer.

Iirc it used deuterium (heavy water) as the moderator, so if it got hot, the moderator boiled away and the fast neutrons escaped without being captured and driving fission.

(I thought the main reason for Chernobyl was the operators disabling the safety features "to see what will happen"!)

Cheers,
Wol

Europe needs hyperscalers (lots of them)

Posted Feb 12, 2026 17:38 UTC (Thu) by malmedal (subscriber, #56172) [Link]

> I remember our AGR reactor technology got overwhelmed by the American PWR reactors, despite being much safer.

Don't know if they were safer, but it's clear they were more expensive.

> Iirc it used deuterium (heavy water) as the moderator

No, graphite for moderator, CO2 as coolant. They used control rods to control the reactivity.

> "to see what will happen"

There are very conflicting stories about the details, but it is clear that it was a pre-planned test, deemed necessary to verify correct operation. It was supposed to be done by the day-shift, but it was delayed, so the unprepared night-shift got the job.