Orano Mining
Corporate Social Responsibility
Report 2017
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Mining site remediation is an integral part of the mining cycle which comprises: exploration, development, mining and post-mining (monitoring and reconversion). Remediation is taken into account right from the exploration and development phases of the mining project. Although some remediation work is carried out while the mine is in operation, and studies are updated throughout the active period, most of the remediation work takes place when mining operations cease due to depletion of resources or for economic reasons. It is followed by a monitoring phase to guarantee that the site does not have any negative impact on the environment. In the mine closure process, beyond the technical parameters, it is also essential to address social and societal aspects, with a view to mitigating the socio-economic effects of the closure. Finally, whenever it is possible to do so, Orano Mining is particularly attached to reconverting former mining sites to give them a new lease of life.


In the mine remediation phase, the main obligation incumbent on the operator is to limit the impact of the former mining site on the environment and population to a level that is as low as reasonably achievable. All the actions taken as part of a remediation plan are implemented in accordance with the environmental standards in force, in coordination with the competent authorities and in consultation with local populations.

The main challenges of mine remediation are:

  • stability of the mining works and dikes;
  • the residual impact of the site on the environment, and on water management in particular;
  • management of tailings and waste rock from mining;
  • social acceptability;
  • sustainable monitoring;
  • achieving an economic optimum.

The main objectives of a remediation plan are as follows:

  • ensure long-term stability in terms of public health and safety;
  • reduce residual impacts to levels that are as low as reasonably possible (ALARA);
  • limit the land surface subject to usage restrictions;
  • successfully integrate the site into the landscape of its environment;
  • support the reconversion of the site or its opening up to other surface activities;
  • inform of and share remediation options with stakeholders.

All Orano Mining's mining sites are covered by a specific remediation plan.


The Cluff Lake mining site, located in the North-West of the State of Saskatchewan in Canada, operated for 22 years (1980/2002) and produced 23,500 metric tons of uranium. It consisted of 4 open-pit mines, 2 underground mines, and an ore processing plant with storage of tailings. The site underwent remediation from 2004 to 2006: filling-in of open-pit mines, rendering secure of underground mining works, demolition of the plant, coverage of tailings and revegetation of the entire site. The site continues to be monitored. The environmental results of this monitoring are compliant with regulatory requirements meaning a transfer of responsibility for the site to the State of Saskatchewan can now be envisaged.


There are several phases involved in the remediation of a mining site: a study phase, a works phase and a post-works monitoring phase.


The first study consists of defining the remediation strategy best suited to the site by taking account of its specific constraints: location, topography, climate, real estate and regulatory constraints, type of works, requirements from impact studies, environmental constraints, socio–economic environment, commitments made to different stakeholders (local authorities, residents) and by planning ahead to take into consideration new usages of the land for new agricultural, forestry or artisanal activities, etc.

This involves a detailed inventory of the site before (initial state) and after mining operations, its history, and additional technical studies (hydrogeological, geotechnical, radiological studies, etc.) making it possible to prepare a remediation plan and draw up a proposal to be submitted to the Authorities and forming a basis for dialogue with the stakeholders. Field tests may also be conducted during the operation phase to test out and refine assumptions in the remediation plan.

Mining works

Measures for the making safe of mining works are determined depending on the nature of the mine and the facilities concerned.

For underground mines, the aim is to ensure the stability of the works and to seal off access to all pit bottom to ground level connecting structures: pits, cross-cuts, ascending and descending shafts. Stability calculations are done for works close to the surface and, depending on the their results, reinforcement works may be conducted. If safety cannot permanently be assured, safety perimeters may be set out on the surface, established physically in the form of enclosures, within which usage restrictions may apply; specific monitoring of upwelling of waters and potential points of emergence is planned for in advance, with particular attention devoted to an improvement in water quality. Hydrodynamic and hydrogeochemical modeling studies aid in the forward planning of additional measures such as water treatment for example.

Open-pit mines may be either filled in with available waste rock and tailings or transformed into water features after partial filling-in. The chosen option depends on the commitments made (for example within the framework of requests for mining permits), the configuration of the site, the availability of materials, a specific request on the part of a local authority, and costs, whilst of course treating the safety of local residents as a matter of top priority. Waste rock stockpiles are remodeled and revegetated depending on the local context.

In the case of ISR (in situ recovery) operations, particular attention is paid to the quality of the water table in which the mined deposit is located. In general, regulations require that water quality be restored to a level close to its original level. It is worth noting that the initial quality of these waters (waters that may be naturally saline and radioactive due to the local geological context) is such as to prevent anything other than industrial use. There are several methods of restoring these water tables, such as the pumping out of waters, treating them in a surface facility and reinjecting them, or alternatively the injection of reagents enabling the treatment of waters in situ. The preferred method is natural attenuation: naturally-present or newly-formed minerals "trap" the pollutants by adsorption. Numerous studies are currently being carried out to gain a better understanding of this phenomenon and to see how it can be speeded up.

The majority of facilities on the surface are dismantled: such as the headframe, loading hoppers, etc. Certain buildings (former offices and workshops) may be retained to allow a new activity to be developed on the site.

Travaux Miniers Puy de l’Age (Limousin) – before/after remediation

Ore processing facilities

To extract the uranium, the ores are processed by static or dynamic leaching depending on their uranium content (0.03 to several percent) in accordance with the following process: crushing, grinding, leaching with acid or base chemicals, extraction, purification and precipitation. At the end of the process, uranium is put into solid form, known as "yellow cake" with a uranium concentration of around 750 kg/t. The solutions with uranium content pumped out as part of ISR mining operations are processed using the same extraction and purification processes.

When mining activity comes to an end, these facilities, specific to the processing of uranium ore cannot be reused, except for a similar purpose. They are dismantled and demolished. The materials resulting from dismantling and demolition are stored on site (see storage of processing residues).

Waste rock

Waste rock is made up of earth, sand or rocks containing little or no uranium ore. It still needs to be extracted, however, to access the mineable ore itself. These substances present no radioactivity or very low levels of radioactivity. This waste rock is mostly used for the remediation of former mining sites, or stored in piles in the immediate vicinity of where the works were carried out.

Under the PNGMDR, Orano has conducted sampling campaigns on several remediated sites to characterize the evolution of waste rock storage and its potential impact for the natural environment. A multi-year study is ongoing to develop predictive models of the migration of uranium from the rock piles to the environment.

Mining tailings

Tailings are the part of the finely crushed ore which does not contain uranium, or only contains very little, and is produced following the separation of rock and uranium in the ore processing plant (production of uranium concentrate). They are in the form of clayey sand and contain still 70% of initial radioactivity. They are stored near the processing plants. Their storage and inspection make up a considerable portion of remediation and monitoring operations.

Under the PNGMDR (Plan National de Gestion des Matières et Déchets Radioactifs - French National Plan for the Management of Radioactive Materials and Waste), Orano is required to continue the study of the evolution over time of ore tailings stored in France. This action must ultimately be accompanied by the development of models to predict the long-term impact of the tailings, taking into account both normal and degraded scenarios.


Philippe Crochon, Remediation and Environment Expert within the Mining BU, talks about the difference between waste rock and tailings. He also explains how the remediation of former mining sites requires a broad range of know-how in particular in geology, hydrogeology and radiometry.

Storage of tailings

Tailings are the solid part that is left over and unusable after the uranium has been put into solution when the ore is processed. Tailings from dynamic leaching take the form of fine clay sands with the same mineralogical composition as the original ore, along with various other additional chemical precipitates, and contain approximately 5% of the initial uranium content and most descendants of the decay chains of uranium. Their level of radioactivity is around 70% of that of the original ore. Tailings from static leaching are of a coarser grain size (10 to 100 mm) and have a uranium content of several tens to hundreds of ppm. All these tailings are thus naturally radioactive (total radioactivity of several hundred Bq/g) and have a long lifetime.

They are stored in former open-pit mines, in ponds enclosed by containment dikes or behind a dike blocking a thalweg (valley, former river bed). These storage areas may cover tens of hectares and hold millions of tonnes of tailings. These pose a major challenge when it comes to remediation.

The remediation of tailings storage areas: given their dimensions and the tonnages involved, the storage areas formed during the operating period of plants are kept in place at the end of operations. A cover, generally in solid form, is placed over the tailings to form a geo-mechanical and radiological protective barrier, with a low level of permeability making it possible to limit risks of intrusion, erosion, dispersion, infiltration and radiological exposure of surrounding populations. This cover, of around 2 m thick, is, where possible, made of the materials available on site (waste rock from mining), creating a topography favorable to the proper management of meteoric waters and taking account of risks of future settling of the ground. When tailings from static leaching are present on site, they can either be put in the primary layer, which means it is possible to put all the different types of tailings together in one place, or be remediated in the same way as tailings from dynamic leaching. Depending on the climatic context, a final covering layer of topsoil is added to allow the site to be revegetated. Tests are carried out before the start of works to check the effectiveness of the chosen materials, optimize the thickness and the geotechnical characteristics of the cover.

Storage areas can also be covered by a layer of water, which offers considerable radiological protection, in particular with regard to air quality. Certain sites are enclosed by dikes, while others may be classified as "large dams" ["grands barrages"] in the regulatory sense of the term. Stability studies are conducted and reprofiling or reinforcement works may be undertaken if necessary.

It is worth noting that one of the benefits of the ISR method of mining is the absence of tailings to be managed.

Each tailings storage area is monitored in a way which is adapted to the particular challenges of each of the sites concerned. These are ICPE-classified environmentally regulated storage facilities (ICPE = Installation Classée pour la Protection de l’Environnement) and therefore covered by the French Environmental Code.

Monitoring of sites

The role of the mining operator is to limit the impact on populations and the environment to a level that is as low as possible and in regulatory compliance and to verify this through systematic and regular monitoring. This monitoring involves checking the ways in which uranium and its decay products, as well as various other substances related to mining activities, such as drained-off acid, may be transferred at sites and in the surrounding area. The monitoring network established concerns the checking of water (underground and surface water), the atmosphere (dose rate, radon, dust) on site and in its immediate environment, bio-indicators (sediments, aquatic plant life) and the food chain (samples of vegetables, fruits, milk, and fish taken close to sites). If necessary, waters originating from mining works and storage areas are treated to correct one or more of their radiological and chemical characteristics before being released into the surrounding environment. The treatments carried out are of a physical-chemical nature (addition of reagents, resins) or sometimes passive methods may be used (limestone drains, wetlands).

The results of all these checks allow the actual Effective dose (Dose Efficace Annuelle Ajoutée DEAA) added to the local background level of radiation (radiological impact) to be assessed on an annual basis for populations living close to sites. In France, in accordance with the French Public Health Code, this dose must be less than 1 mSv/year. It should be noted that the main factor leading to exposure is generally radon. It is difficult to determine the origin of radon, whether it is of natural or industrial origin, bearing in mind that sites are located in areas where concentrations can be naturally high (areas of granite or with the presence of naturally occurring veins of rock in situ). To adapt to the specificities of each site, measurement stations are installed which are not subject to any influence from mining activity, in an area with similar geological and topographical context to the site being monitored. The results obtained provide a benchmark for the "natural environment", and thus make it possible to reliably assess the potential impact of the site on its environment.

Planning and undertaking remediation of the mining sites
that have been in operation for 50 years

For around 40 years, SOMAIR and COMINAK have exploited the uranium deposits in the department of Arlit, using open-pit mining techniques in the case of SOMAIR and underground mining techniques for COMINAK, and practically the same ore processing technique to produce the Uranate concentrates for the market.

In accordance with the existing regulations, the mining companies have each prepared a master plan for the remediation of their operated sites and a surveillance network to monitor the effectiveness of the measures.

The objectives of a remediation plan are as follows:

  • Ensure long-term stability in terms of public health and safety
  • Reduce residual impacts to levels that are as low as reasonably possible (ALARA)
  • Limit the land surface subject to usage restrictions
  • Successfully integrate the site into the landscape of its environment
  • Support the reconversion of the site
  • Inform of and share remediation options with stakeholders
  • Comply with the regulations in force

These master plans are regularly reviewed as mining operations evolve.

In 2017, the remediation plans, including definition of the remediation options and a cost assessment, were drawn up taking into account the known development plans for the mines over the coming years.

These plans have been presented to and discussed by the Technical Committee, whose members include representatives of the different shareholders and the authorities in charge of these areas of expertise.

Environmental monitoring in france

Monitoring the environment involves checking all the ways in which uranium and its decay products may be transferred at former mining sites and in the surrounding area. This mainly means monitoring water, the atmosphere, the food chain and plants. This monitoring is carried out within the framework of prefectural orders, specific to each of the sites and covered by reports submitted to the Government authorities on a regular basis and presented to Site Monitoring Committees.

Each year, over 30,000 analyses are performed on the air, water, sediments and the food chain.

  • Air monitoring
    This monitoring chiefly consists in measuring exposure to ambient radioactivity, namely ionizing radiation and the air inhaled. Measurements are taken continuously, both at the site and in the nearby area, using specific dosimeters.
  • Water monitoring
    Hydrological and hydrogeological studies are performed at sites, allowing better understanding of the environment type and the composition of local water. On certain sites, where necessary, the water undergoes treatment before being released into the natural environment to ensure it meets the environmental standards in force. Our experts design the water treatment processes which are then applied and optimized. One process they have implemented, for example, is so-called "passive" treatment using limestone drains, by adsorption into beds of sludge or turf, and they have also optimized the physical-chemical treatment method, which is currently the method most frequently used.
  • Monitoring of plants and the food chain
    In addition, sampling and analysis are regularly carried out on plants and other components of the food chain, including aquatic and land fauna, aquatic flora, the fruit and vegetables produced in nearby gardens, and the milk supplied by animals that have grazed in meadows near sites or drunk from receiving water courses.

Management of post-mining

Following the mining of the uranium ore, mining sites are remediated to limit the residual impact of the past activities both for safety reasons and to preserve the environment.

The remediation and monitoring of these sites falls within a demanding and evolving regulatory framework. We also see this as an opportunity to draw on and promote an area of expertise mastered by our teams covering the major steps of the remediation and post-mining cycle.

This phase must be prepared as far upstream as possible, from the exploration phase. It requires the mobilization of specific scientific expertise as well as technical, economic and social know-how.

We would like to offer you the opportunity to gain insights into the major challenges related to these activities, and to come with us around the world to better understand the main environments in which we work. The prinicpal challenges we encounter in our scope of work relate to:

Preparing for remediation from the feasibility studies phase

Example in Mongolia
  • Environmental and societal acceptability of uranium deposit exploration and mining projects
  • Optimization of ISR (In Situ Recovery) technology
Identity card of the mining project
  • At end 2017: 11 exploration licenses and 3 mining licenses (Umnut, Dulaan Uul and Zoovch Ovoo)
  • 54,640 tU of resources registered in 2013 for the Zoovch Ovoo deposit and 4,750 tU registered in 2016 for the Dulaan Uul deposit
  • ISR (In Situ Recovery) pilot conducted in 2010/2011 at the Dulaan Uul site
  • Construction and operation of an ISR pilot (extraction + processing) on the Zoovch Ovoo site between 2017 and 2019
  • Aim of the pilot: to confirm and improve the technical and economic conditions of the project and, eventually, at the end of the feasibility study, transform our resources into reserves
Remediation Plan – Starting Point
  • Periodic monitoring through a network of piezometers
  • Remediation of drilling platforms
  • Study for dismantling of the industrial facilities and well fields
  • R&D Program: demonstration of natural mitigation in aquifers
  • Hydrogeological studies
  • Plantation of Saxauls (protected local trees) in remediated areas

Planning for the remediation of a mining site in operation for 15 years

Example in Kazakhstan
  • Start remediation while mining operations still in progress
  • Management of waste generated by mining operations
  • Model the overall behavior of aquifers under remediation
Identity card of Katco site
  • Creation of joint venture between Orano (51 %) and KazAtomProm (49 %) in 1996
  • The first uranium mining operation in the world to use the ISR technique
  • Total aggregate volume of more than 35,000 tU produced since 2006
  • Mine in operation with production of 3,500 tU in 2017
Mine in operation and remediation work on site
  • Study for dismantling of the well fields and processing facilities
  • Feasibility study to restore the site to its primary use (forestry)
  • R&D program to confirm and speed up the remediation of the aquifers tested on-site, mainly through natural mitigation

Planning the remediation of a mining site in operation for more than 50 years

Example in Niger
  • Remediate a site with a history of several decades in a desert area
  • Social and societal impact of the closure, in particular for the town of Arlit
Identity card for the SOMAÏR site in Niger
  • Site mined since 1971
  • Mining of uranium deposit in Open-Pit Mines then dynamic and static processing plant
  • Aggregate production of some 70,000 metric tons with annual target of 2,100 tU in 2017
Mine in operation and in-depth remediation plan
  • Site subject to environmental monitoring
  • Validation by the authorities of the remediation plan with definition of remediation options for each sector of the site

Preparing the transfer of a remediated site to a supervisory authority

Example in the USA
  • Transfer of a remediated site to the U.S. Department of Energy (U.S DOE)
Identity card of the American mines
  • 2 main sites: Lucky Mc & Shirley Basin, mined from 1953 to 1993
  • Open-pit mine, underground mining works with processing plant by alkaline leaching (first industrial application in the USA)
  • More than 27,000 tonnes produced and 20 million tonnes of tailings
  • Full remediation and transfer of site to the U.S. Department of Energy (DOE)
  • Supervisory authority: US Nuclear Regulatory Commission (NRC), supervising monitoring of the site through the issuing of a license
  • Monitoring of the storage of tailings: Lucky Mc (5 boreholes), Shirley Basin (14 boreholes), all analyzed 4 times/year; parameters analyzed: level of water, pH, temperature, heavy metals, uranium, radium and thorium

Conducting monitoring and oversight of remediated sites

Example in Gabon
  • Conducting environmental monitoring of a site closed since 1999
  • Reconstruction of 201 dwellings for the local population following inspections and the detection of a radiologically contaminated dwelling in the former mining town, conducted in cooperation with the Gabonese State
Identity card of the COMUF remediated mine
  • 5 deposits in the Haut-Ogoué in Mounana mined from 1958 to 1999
  • Open-pit mine and underground mining works with a processing plant
  • 7,600,000 tonnes of ore extracted at 3.73 ‰
  • Production of Yellow Cake: 26,600 tons
  • Remediation of the site from 1999 to 2004, validated by the IAEA
  • Parameters monitored:
    • Water: 17 sampling points
    • Air: 13 dose rate measurement stations and 6 radon measurement points
    • Food chain: 8 sampling points for kassava and fish
    • Stability of the dike (topographical measurements)
  • Independent environmental inspections performed by the Gabonese Nuclear Safety and Security Agency (Autorité de sûreté et de sécurité gabonaise – AGSSN)

Providing a second life for a remediated site

Example in France
  • To achieve the reconversion of the former mining site in an economic framework such that new projects can be located at the site
Identity card of the remediated mine of Bosc-Soumont
  • Site in Hérault mined from 1959 to 1997, and remediated between 1998 and 2002
  • Open-pit mine and underground mining works, ore processing plant
  • 5.1 million metric tons of ore extracted
  • Production of Yellow Cake: 14,630 metric tons
  • Site reconverted into a regional industrial park (Parc Régional d’Activités Economiques, opened in 2010), providing premises for a recycling company and the installation of a photovoltaic facility (commissioned in 2014)
Site reconversion and community involvement
  • Regional industrial park (Parc Régional d’Activités Economiques Michel Chevalier), located on the area of the former quarry since 2010, with a total surface area of 120 ha, is now home to three companies, working in a variety of industries: packaging, metal industry and laser-cutting of stone
  • Inert waste recycling company located in a former Open-Pit Mine
  • Photovoltaic commissioned by Engie Green in 2014:
    • 21 hectares
    • Capacity of 9 MWc = the annual electricity consumption of around 6,000 households
  • Construction of a second photovoltaic facility by Engie Green currently in progress:
    • Expected to be commissioned in 2018
    • 6 hectares
    • Capacity of 5 MWc = the annual electricity consumption of around 3,000 households
  • Project for the installation of a third photovoltaic facility by NEOEN to be commissioned in 2022:
    • 8.4 hectares
    • Capacity of 3.5 MWc = the annual electricity consumption of around 1,910 households
Travaux Miniers             Solar power plant of Lodève (Le Bosc)                                     Le Bosc Zone for artisanal activities
                                                                                                                      situated on the site of the former plant