The Nuclear Industries of Brazil (INB – Indústrias Nucleares do Brasil) has received an operating licence (No 1709/2025) to decommission the Caldas uranium in Minas Gerais. The licence, issued by the Brazilian Institute of Environment & Renewable Natural Resources (Ibama – Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis) to the Caldas Decommissioning Unit (UDC – Unidade de Descomissionamento de Caldas), is valid until January 2031.
It is the first uranium decommissioning licence issued by Brazil and is the result of the work of a technical team designated by a work order to conduct the environmental licensing process for the project. The multidisciplinary group includes members of three Ibama boards specialising in licensing, environmental quality and environmental protection, as well as officials from Pernambuco, Paraiba, Minas Gerais and Goias.
Technical meetings of the Ibama team were held with INB representatives, as well as a survey at the UDC to verify the situation of the facilities. There was also participation from the National Nuclear Energy Commission (CNEN – Comissão Nacional de Energia Nuclear), which has competence on radiological aspects. As a result of the activities of the technical team, the parameters of licence were specified including the plans and programmes for environmental control and monitoring to be implemented in the project.
The licence lists the obligations imposed on INB including effective progress in the recovery process and remediation of the area impacted by the mine, to promote greater environmental safety at the facilities. The licence specifies the need for annual public meetings as well as the improvement of communication tools in order to keep the community informed and engaged in the decommissioning process.
The Caldas mine began operations in 1982 and closed in 1995. Since then, the UDC has been decommissioning the structures related to the extraction and processing of uranium. During this period, the facilities were also used for the processing of materials from other regions in a series of isolated projects, as well as for the storage of nuclear material from sources outside the site.
INB said in September 2023 that it had completed the first stage of demolition of buildings at UDC. Altogether 12 buildings were demolished comprising 1,900 square metres of disused structures including the cooling tower. INB said the area where the buildings were located will be restructured using local soil.
Ore extraction at the Caldas mine was from an open pit. Of the material removed, aside from that extracted for uranium, some was used on-site for road construction and building embankments while the remainder was disposed of onto two major rock piles. There are a number of potential historical and current environmental impacts to groundwater as a consequence of discharges into streams which then flow off site, according to the International Atomic Energy Agency (IAEA).
The former open pit currently forms an acidic lake of 1200 metres diameter and 180 metres depth. The complex comprises the disused uranium mill, the uranium mill tailings basin, and deposits of radioactive materials including some transferred from other sites.
In 2012, INB presented its Plan for Recovery of Degraded Areas following a two-year study addressing hydrogeological, geochemical, and radiological situation. The programme provides for the recovery of the environment of the area comprising the mine, industrial facilities and tailings dam. The work was expected to extend over nearly two decades.
The recent demolition activity started in May 2023 and cost BRL645,000 ($130,675). The work also included the processing of waste generated by the demolitions. Management of tailings, which can be used in civil construction, is undertaken by INB, which can use them to rebuild internal roads and surrounding areas. Materials such as wood, plastic, ceramics and tiles have already been used for properly licensed landfills.
Among the demolished structures were old changing rooms, office, warehouse, the Caldeira Command House, the Machinery Command Centre, the Command House of the Water Treatment Station and the old Water Treatment Station. As part of the decommissioning process, in 2022 INB sold about 500 tonnes of scrap to the UDC. The process of discarding items started in September 2019. The sale included various goods and materials, vehicles and equipment, as well as electronics and information technology not used by the company.
UDC covers an area of 1,360 hectares in the municipality of Caldas. Currently, the control of the remaining materials from uranium mining and beneficiation is carried out through acid water treatment, waste and solid tailings management, dam safety management, environmental management of the area, including vegetation recomposition, worker safety management and radiological and environmental monitoring of the region.
