The cancellation of new nuclear power plants in the US was overwhelmingly due to economics. In the first nuclear buildout, reactors came in more expensive than promised, demand growth slowed, and then the grids were opened to non-utility generators. This happened again more recently with the nuclear renaissance: projected demand growth again failed to materialize, reactor construction was more expensive than promised (Watts Bar 2, V.C. Summer, Vogtle), and large quantities of fracked gas became available.