Part of the problem may be that it's a translation of a translation, unless anyone here (MiMo? Muzu?) can track down the original Japanese words used.
So we don't know whether the person used a noun or a verb, and if the latter, I don't know whether the verb tense could change the meaning in Japanese.
For example, to me 'the reactor core melted temporarily' doesn't sound right, because that sounds as if it completed the action, reached a different state, i.e., lost its firm structure -- but then (magically) regained it. However, 'the reactor core was temporarily melting' sounds better, because that could simply mean that it was actively melting for a while and then stopped melting further.
To me the difference with 'melt down' is that 'down' means completely. Especially in a nuclear context, I've always assumed that a meltdown means total catastrophe, that it can never be restored or used again, but IANA physicist ...
Whatever is happening, it sounds ominous. This morning there was highly radioactive water a mile out to sea and in all the tunnels underground, not just in the basement rooms. What I don't understand is how they can ever stop it from just continuing to get worse, if they can't contain the water and if the heat is continuing to make it expand in quantity, and if they can't get people in there close enough to do anything.
This is probably a stupid layperson kind of question, but isn't there any kind of protective gear they could use to shield workers? Say, like people wear lead vests near x-ray machines. Does lead stop radioactive matter (? rays?) or just reduce/slow it? I assume entire lead suits would be too heavy, and not possible to seal against water, but could they build like a little lead-lined tank of some sort, with robot arms or something, to allow them to get closer? I assume not, since they haven't, but why not?