tl;dr *sigh* It's not just done with renaming.
Nucular is one horrible tag. For the reason you mentioned and for a couple more, well, mainly inconsistency. (And MATT is -2, in words: minus two.)
Let us just start with the basics, the scope definition.
There is no tag wiki for this tag … yet!
Who would have thought... well, at least there is an excerpt, kind of.
relates to the dynamics and processes that occur within and interactions between the nuclei of atoms.
I am not an expert in linguistics, but this is not even a sentence, isn't it? Set aside, I have actually no clue what that is supposed to mean. If someone could please enlighten me.
Since we don't have a defined scope, we can maybe look at the top voted question to determine consistent use. We can and we will. Brace yourselves, this is going to be messy.
The last element's atomic number
Basically the topic is Nucleosynthesis.
Do the names of some elements have anything to do with Planets?
This has something to do with elements, right? It starts great when the second highest question is a miss-tag.
Is there a simple field test for heavy water?
I know that there is a branch of chemistry out there called radiochemistry, which is if I recall correctly (mostly) dealing with unstable isotopes in aqueous solution. (I only had an introductory course at university and that has been about ten years ago.) That of course includes radioactive decay and radioactive isotopes.
Turn lead into gold via radioactive decay
This one is about radioactive decay or more general particle decay.
If radium has such a long half-life, how can radon possibly be a threat to us?
Radioactive decay again. We are getting somewhere after all.
Also I would like to bring these comments to your attention:
Isn't chemistry all about electrons? How can this be on-topic? – Peter Mortensen
Radioactivity is a part of nuclear chemistry. – Emu27
Radical formation via tritium to helium decay
We have a decay here again... I see a pattern emerging, but stay tuned.
How is the electron "trapped in the crystal" in irradiated NaCl?
This is about excited states I think. Does this have anything to do with being nuclear?
Why can't light pass through a gold foil, but alpha particles can?
electromagnetic-radiation? I read alpha-particles somewhere before, but I think this question does not belong here.
Understanding Beta Decay
Apart from a horrible title, this is again about decay, but stay tuned, there's something coming, soon.
What is the reason behind choosing the specific elements used for the synthesis of heavier elements?
Like 1. Great.
I would like to stop now... it's already getting overly crowded in this post.
We can deduce the following:
Out of the top 10 questions, three were not related to nucular, that means (at least) 30% are tagged wrong.
We have Nucleosynthesis twice, and we could probably find more. Does it warrant an own tag? I'll let you do the MATT.
We have one question that is related to radio-chemistry. I think this is an interesting topic, which warrants a tag by itself, even if it is likely to fail MATT, because there are maybe not enough questions to go around.
We have four questions about radioactive decay. So I guess we could use that as the primary scope. So why not use:
Questions relating to radioactive substances and the chemistry of radioactivity.
Oh wait, that is the tag-wiki excerpt for radioactivity.
The tag is without real scope. Many of the uses might be entirely wrong. Most of the question could be tagged with radioactivity instead. This is probably a task for TRE. It is to determine if nucleosynthesis warrants a unique tag.
It is not done by simply renaming the tag. It needs to be nuked (sorry about the pun - well, actually I am not). Since there are 9 questions with only this tag, I suggest retagging manually.
A different route would be to merge it into radioactivity and then clean it out. This way the tag is gone, but the problems remain.
Let me know in the comments what you think.
Thank you for your attention.