alt Hacker NewsFukushima. It was a Gen 1 plant which already has the issue that a thermal runaway is possible. There were other examples of this happening like TMI. The backup for Fukushima was onsite generators which were flooded and ultimately failed causing the meltdown.
The safety lessons we learned from all gen 1 reactors was to apply passive shutdown mechanism where if input power fails fission ultimately stops. That's not something that can be applied across the fleet because it requires more infrastructure and an almost complete redesign of the reactor's setup. Which is why these early reactors all have a potential risk of thermal runaway.
Edit: It looks like all gen Is have been decommissioned as of 2015, which is great. But we really should now be talking about decommissioning gen IIs and leaping forward to Gen IVs.
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Fukushima Daiichi Nuclear Power Plant was NOT using Generation I reactors.
"Gen I refers to the prototype and power reactors that launched civil nuclear power. This generation consists of early prototype reactors from the 1950s and 1960s, such as Shippingport (1957–1982) in Pennsylvania, Dresden-1 (1960–1978) in Illinois, and Calder Hall-1 (1956–2003) in the United Kingdom. This kind of reactor typically ran at power levels that were “proof-of-concept.”"
https://www.amacad.org/publication/nuclear-reactors-generati...
> if input power fails fission ultimately stops
AIUI fission was stopped basically immediately. The problem was removing the decay heat from the fission by-products; without pumps to move cooling water that didn't happen.
I think modern reactor designs have enough passive cooling that this failure mode can't happen. There are a lot of active reactor plants where it still could be possible though.
Fukushima Daiichi is irrelevant to European nuclear reactor safety.
That's a big nevertheless.
It's worth noting that the Fukoshima disaster
1. Lead to basically zero direct deaths
2. Was caused by the forth most powerful earthquake to have ever been recorded in the world (since ~1900), and the most powerful earthquake ever recorded in Japan
3. ~20,000 people died due to the Earthquake
Requiring a nuclear plant in Belgium to be safe enough to survive what caused the Fukoshima disaster is probably not a good use of money