Question: Is there a nuclear power reactor in the State of Hawaii?
Answer: No. Hawaii is one few states which doesn't have a nuclear power reactor.
It's worth mentioning that no one can develop a nuclear power plant in Hawaii without prior approval from two-thirds of each house in the Hawaii State Legislature, as stated in Hawaii Constitution Article 14, Section 8:
"No nuclear fission power plant shall be constructed or radioactive material disposed of in the State without the prior approval by a two-thirds vote in each house of the legislature."
In other words: You don't need to worry about a nuclear power plant being built in Hawaii, because even bringing up such as idea is considered political suicide in Hawaii.