First, a containment structure[1] is a key feature in any reactor[2]. These are massively over-engineered specifically to contain even unlikely problems. We learned that this was important after the SL-1 accident[3]. As you suggest, this is a feature designed to fail safely - the containment should keep the rest of us outside the building safe, and doesn't say anything about what happens to the stuff in side.
> meltdown
This term is thrown around a lot, and while solid fuel melting in a traditional reactor is a serious event, a lot of people seem to think that "meltdown" is some kind of terrible or damaging event. The reason people in the nuclear industry panic over a possible meltdown has little to do with safety; up until that point you could - in theory - still reasonably believe that the reactor could be fixed and (eventually) restarted. After a meltdown, you have to assume the core is trashed and is now a financial liability instead of your main source of revenue.
Meltdowns are a terrible event financially. The actual melting of the fuel involves the passive-safety, which are usually designed to drain that fuel into (multiple) areas where it can cool down without criticality risk.
All of this is still discussing very old features. This is like worrying about today's computers because vacuum tubes are fragile and need to be replaced when they burn out. Modern reactor design is very different, because we learned form the problems that happened in the original designs, just like any other technology. Unfortunately, propaganda based on radiophobia has been a serious roadblock. Ironically, this means we're stuck using older designs that should have been replaced decades ago with modern reactors that emphasis passive safety.
If you're interested in a brief overview of these problems (and why some of us believe thorium breeder reactors are the answer for many of these problems), I recommend watching "Th"[4]. Just remember it's an overview, and they skip over some of the details to keep it short.
> meltdown
This term is thrown around a lot, and while solid fuel melting in a traditional reactor is a serious event, a lot of people seem to think that "meltdown" is some kind of terrible or damaging event. The reason people in the nuclear industry panic over a possible meltdown has little to do with safety; up until that point you could - in theory - still reasonably believe that the reactor could be fixed and (eventually) restarted. After a meltdown, you have to assume the core is trashed and is now a financial liability instead of your main source of revenue.
Meltdowns are a terrible event financially. The actual melting of the fuel involves the passive-safety, which are usually designed to drain that fuel into (multiple) areas where it can cool down without criticality risk.
All of this is still discussing very old features. This is like worrying about today's computers because vacuum tubes are fragile and need to be replaced when they burn out. Modern reactor design is very different, because we learned form the problems that happened in the original designs, just like any other technology. Unfortunately, propaganda based on radiophobia has been a serious roadblock. Ironically, this means we're stuck using older designs that should have been replaced decades ago with modern reactors that emphasis passive safety.
If you're interested in a brief overview of these problems (and why some of us believe thorium breeder reactors are the answer for many of these problems), I recommend watching "Th"[4]. Just remember it's an overview, and they skip over some of the details to keep it short.
[1] https://en.wikipedia.org/wiki/Containment_building
[2] a feature that was missing at Chernobyl, which is one of many reasons that accident affected such a large area
[3] https://www.youtube.com/watch?v=qOt7xDKxmCM
[4] http://thoriumremix.com/th/