Forsmark nuclear power plant's staff was first to discover the raise of radiation level - which was first considered as concequence of some failure on their own station.
Here you can find a detailed chronology of how it happened:
http://www.zetterberg.org/Papers/ppr1986b.htm - It's a paper by Hans L Zetterberg was prepared prepared for the Eleventh Annual Symposium of the Uranium Institute in London, September 2-4, 1986. It gives a lot of interesting data of public opinion surveys of the population's relation to nuclear power plants in Sweden before and after Chernobyl. One can notice a dramatic change from a rather positive position to quick raise of negative tendencies and actually fear of nuclear energy. In many ways those tendencies still exist today. Although the distance between Chernobyl and Stockholm is more than 1,000 km, Sweden was more polluted than many neighboring countries due to radioactive rain.
Quoting Zetterberg here:
Sweden achieved its consensus on nuclear energy in a referendum in 1980 which approved of the nuclear investment in 12 reactor blocks, and in a parliamentary decision later the same year that nuclear power should be phased out by the year 2010. Sweden is the only country in the world with a formal decision to eventually abandon nuclear power. There is even a law prohibiting anyone from making plans for future investments in nuclear energy.
The decision to abandon nuclear power by 2010 has not been taken very seriously in all quarters of government and industry. It has often been said that a future parliament may reverse the decision when reviewing the track record of nuclear power. The environmentalists fear that the talk of phasing it all out by 2010 is a ritual that is designed to protect the heavy investment already taken.