World map of member countries of the Nuclear Energy Agency–NEA.
Member countries as of 2014, in alphabetical order: 

Australia, Austria, Belgium, Canada, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Japan, Luxembourg, Mexico, Netherlands, Norway, Poland, Portugal, Russian, Slovakia, Slovenia, South Korea, Spain, Sweden, Switzerland, Turkey, United Kingdom, United States.
Own work.

NEA website "Member countries and dates of accession"
Rfassbind