The USA had the first nuclear passenger ship; NS Savannah back in the 1960s. Check out this link;
NS Savannah was a signature element of President Eisenhower's Atoms for Peace program. She was constructed as a joint project of the former Atomic Energy Commission (AEC) and the Maritime Administration. She operated from 1962 to 1965 in experimental service, at which time the AEC issued her commercial operating license number NS-1. Savannah continued in demonstration service as a cargo and passenger ship until 1970 when she ended her active career. She was defueled in 1971 and her reactor made permanently inoperable in 1975-76. About 95% of the power plant is intact and remains onboard ship. Savannah is still licensed by the Nuclear Regulatory Commission (NRC is the successor to the AEC), and will remain so until nuclear decommissioning.