Radioactive element that has “warm nuclei”, roughly (10)

I believe the answer is:

lawrencium

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'radioactive element' is the definition.
'lawrencium' can be an answer for 'element' (lawrencium is a kind of element). I am not certain of the 'radioactive' bit.

'warm nuclei roughly' is the wordplay.
'roughly' is an anagram indicator.
'warm'+'nuclei'='warmnuclei'
'warmnuclei' with letters rearranged gives 'LAWRENCIUM'.

'that has' is the link.

Can you help me to learn more?

(Another definition for lawrencium that I've seen is " Element atomic no. 103".)

I've seen this clue in The Times.

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