100 KW reactor was originally launched between 1959 and 1962 during the exhibition of the Atomic Energy Commission of the United States to South America, and was settled in Uruguay in the 1970s for educational, research and technical staff training purposes, placed in the building of the Center of Nuclear Research (Malvín Norte). Half of the building was intended for the reactor, manufactured by Lockheed Nuclear Products of Marietta (Georgia), purchased with a state investment of two million Uruguayan pesos of that time, including installation costs. Subsequently, Uruguay invested 20 million Uruguayan pesos from the government budget to construct the building and put it into operation. Law 13640, article 259 established that the reactor was the property of Uruguayan government and remained under the purview of the National Atomic Energy Commission. This reactor was operational from the late 1970s to 1985, until it was shut down due to corrosion problems; fuel elements were removed from the core and put into dry storage, waiting to be transported to United States. The installation of this facility did not have any public opinion controversies. Announcement of a nuclear plant A year after the Goiânia accident and two years after the Chernobyl disaster, Uruguay began talks with Canada during the first presidency of Julio María Sanguinetti which advanced until the signing of a cooperation agreement on nuclear energy between the countries in 1988, a fact not known until the Earth Summit (1992). The agreement was almost ratified in Parliament in 1992, during presidency of Luis Alberto Lacalle. Also, a work group was created, which purpose was to evaluate the possibility of use this way to generate electricity in Uruguay. Even though the installation of a nuclear power plant was not mentioned in the agreement, the second article of a report - signed by all political parties and elevated to consideration by the House of Representatives at the regular meeting on August 18, 1992 - established that the installation of nuclear power plants that could result from the implementation of article 215 of Law 16.226 based on the agreement, would require approval by law. The 1992 announcement of the possible construction of a nuclear power plant with loans from the International Atomic Energy Agency in Paso de los Toros caused concern and generated various social movements, which was partially attributed to the proximity of the Chernobyl disaster. Were made mass meetings to inform people about