If not, why not?

Taiwan has an active nuclear power program.  Three nuclear reactors supply most of the power on the island;  there was a major scandal over a fourth plant that was cancelled in the middle of construction.

In 1986, Reagan pressured Taiwan to give up its nuclear weapons program over fears that mainland China would go to war if Taiwan began producing nuclear weapons.  Taiwan gave up its nuclear weapons program in exchange for military hardware and promises of support in the event the mainland decided to attack.