In 1954, the Junta de Energia Nuclear, JEN (Nuclear Energy Board) was created under the direct dependence of the Prime-Minister of Portugal (Decree-Law 9580, of 29th March 1954) aiming at (1) prospecting, mining and milling of uranium ores and (2) development of research activities related to peaceful applications of nuclear energy. To fulfill the second objective, it was decided to create the Laboratório de Física e Engenharia Nucleares, LFEN (Nuclear Physics and Engineering Laboratory), in December 1955.

In June 1956, two particle accelerators – one 2 MeV van de Graaff and one 0.6 MeV Cockroft-Walton – were ordered and arrived in Portugal at the end of of the Summer of 1957.

Still in June 1956, 36 firms were consulted, having in mind the need of acquisition of a 1 MW swimming-pool nuclear research reactor. In 3rd July 1957, a contract was signed with AMF Atomics Inc. amounting at about 400,000 US dollars, for the supply of such equipment.

A pilot-unit for the production of metallic uranium was launched at the beginning of October 1958 and was finally in operation in 1960.

In order to install the services of LFEN, JEN bought for 1.7 million euros (actual price), in September 1956, the land of Quinta dos Remédios located at about 2 km from Sacavém. The Laboratory started to be built in the second half of 1957 – under the supervision of the architect António Lino and engineer Arthur Bonneville Franco – and it was inaugurated on 27th April 1961 by the Portuguese Republic’s President Américo Thomaz. The total cost (land, buildings and equipment) was of 22 million euros, including a contribution of 350,000 US dollars (about 3 million euros) provided by the Government of USA.

The first Director-General of LFEN was Carlos Cacho who was in charge of the Laboratory from January 1959 until February 1975. During the infrastructure construction phase, Carlos Cacho was very well assisted by Fernando Videira, Júlio Galvão and Ricardo Cabrita.

JEN was terminated on 1st October 1979 and LFEN was integrated on the newly created Laboratório Nacional de Engenharia e Tecnologia Industrial, LNETI (National Laboratory for Engineering and Industrial Technology).

In the second half of 1985, LNETI suffered a reorganization and an Instituto de Ciências e Engenharia Nucleares, ICEN (Nuclear Sciences and Engineering Institute) was created among the four institutes of the new Laboratory. ICEN was responsible for promoting research and development activities as well as training in two fields: (1) nuclear reactors engineering and (2) applications of nuclear science and technology for non-energetic purposes.

In October 1992, LNETI became the Instituto Nacional de Engenharia e Tecnologia Industrial, INETI (National Institute for Engineering and Industrial Technology) in which ICEN was kept provisionally until the end of 1994.

"Bearing in mind the importance of a service like ICEN for the development of a modern country, through preservation and development of both technical and scientifical knowledge gathered in this field, of great importance for many sectors including education, industry, agriculture, health and environment (...)", the Government decided to create the ITN, I.P. (Nuclear and Technological Institute) under the dependency of the Ministry of Planning and Land Administration (Decree-Law 324-A/94, of 30th December). Around one year later, ITN was integrated within the Ministry of Science and Technology (Decree-Law 296-A/95, of 17th November), later denominated Ministry of Science, Technology and Universities.

In October 1998, the Department of Radiological Protection and Nuclear Safety was created within ITN (Protection and Radiological Safety Unit, since 2008).

Since June 1999, this Institute became the main national partner with its international counterparts involved in the nuclear energy field.

In 2011, the ITN was transferred to the dependency of the Ministry of Education and Science (decree-Law 86-A/2011, of 12th July) and in December 2011 it was extinguished. A new campus emerges from the transition of the extinguished Instituto Tecnológico e Nuclear, I.P., its mission, its tasks and powers, to Instituto Superior Técnico (IST/ITN). This integration is regulated by the decree-law nr. 29/2012 of February 9 (approved by the Ministers Council on December 22-2011).

The ceremony for the opening of the Loures' Nuclear and Technological Campus of IST has taken place on the 5th July 2012 in the ITN campus, with the presence of the President of IST, Prof. Arlindo Oliveira, the President of the Science and Technology Foundation, Prof. Miguel Seabra, the Dean of the Technical University of Lisbon, Prof. António Cruz Serra, the Mayor of Loures, Eng. Carlos Teixeira, and the Secretary of State for Science, Prof.ª Leonor Parreira.