The Trojan Nuclear Power Plant was a nuclear power plant located in Rainier, Oregon, about an hour outside of the Portland area. It was Oregon's only non-research nuclear reactor. (Reed College has a small research reactor). It was decommissioned in 1992, after a somewhat complicated history.
I don't know enough about the history of energy policy to understand why Portland General Electric first decided to build the reactor. Energy production in the Pacific Northwest has traditionally been using hydropower, with the Columbia River dams being a natural source of abundant energy (although, of course, with some downsides). The dam begin construction in the 1970, so to understand why it was built, we would perhaps have to understand the mindstate of the 1960s. Perhaps they assumed that Portland metropolitan region would outgrow the energy currently available, or they foresaw that a nuclear power plant would be cheaper to run than a dam. For whatever reason, they built the nuclear power plant, and in 1975, it begin running. It was unpopular with a subset of Oregonians, and faced both direct action protests, and also four challenges using ballot measures, none of which passed.
However, the plant did have many technical problems, which both made it expensive to keep running, and also added to the public relations problem. It was also discovered that the plant was built over a fault line, and Portland General Electric finally decided to decommission the plant. The reactor core was shipped by barge to be buried in Hanford Nuclear Reservation, and the cooling tower was destroyed by an explosion.
Growing up, Trojan was one of the litmus tests and causes that the left wing milieu in Portland had. This is doubly ironic, because while I wish that nuclear power had been better thought out as a power source, and not dismissed with so much paranoia, in this case, the protesters were right: Trojan was a badly designed nuclear power plant that seemed to be unnecessary.