Wiktionary
nucular
Etymology 1 a. (context humorous English) (eye dialect of nuclear English) Etymology 2
a. (context botany English) Nut-shaped; of or relating to a nucule — a section of a compound (usually hard) fruit.(reference-book title=Oxford English Dictionary edition=3rd year=2003 chapter=nucule)
Wikipedia
Nucular
"Nucular" is a commonly used metathetic form of the word "nuclear". While it is usually regarded as a mispronunciation, and no dictionaries list this particular pronunciation as correct, several make mention of it because of its increased usage.