An operational repository for very low-level waste
The second category of waste for which a repository now exists in France is very low-level waste (VLLW).
In August 2002, ANDRA opened a VLLW waste repository named CIRES (Centre Industiel de Regroupement, d’Entreposage et de Stockage). This disposal facility is located in Morvilliers, a straight-line distance of 2 km from the Aube repository (CSA), which handles low- and intermediate-level waste.
Cross-section of a “Very Low Level Waste” waste cell
This cross-sectional diagram of a repository cell shows the disposal concept implemented for very low-level waste. To prevent infiltration water from coming into contact with drums or boxes, the cell is isolated by means of plastic sheeting. The filled cell is covered with a thick layer of clay spoil.
© ANDRA ©
The new facility is designed to accommodate 650,000 cubic metres of waste. The first waste was delivered on 1 October 2003. In 2011, the waste inventory by volume stood at 360,000 m3, of which 203,000 m3 had already been disposed of at the Morvilliers repository. More than 30,000 cubic metres are disposed of there each year, and this figure is rising.
The principal sources of VLLW waste include nuclear installations, a few industries that use radioactive mineral ores, restoration work at previously contaminated sites, etc. Thanks to the CIRES facility in Morvilliers, some of the waste generated by dismantling operations can now also be disposed of at a special-purpose repository in France.
ANDRA video about CIRES, the VLLW waste repository in Morvilliers
Much of the waste consists of inert materials (concrete, rubble and earth) or non-hazardous industrial waste (structural steelwork, pipes and ventilation ducts). Their initial radioactivity levels generally lie in a range between 2 and 100 becquerels (Bq) per gram. Within a few decades, the average activity level decays to a few Bq/g, similar to that of natural rock such as granite.
Due to the low activity level, there is no need to take measures to immobilise radioactivity for the long-term. Very basic conditioning is sufficient. The main purpose of the conditioning is to prevent radioactivity from being dispersed by handling operations during disposal. For example, waste subject to a risk of dispersion is packaged in big bags.
Filling a VLLW disposal cell
This photo shows a truck loaded with big bags of waste (generally rubble) arriving at a disposal cell at the VLLW repository in Morvilliers. While a cell is in service, removable roofing is erected to provide shelter from water as waste is brought in.
© ANDRA ©
Approximately 30% of waste is compacted – to reduce its volume – or solidified, in the case of sludge, which is chemically stabilised and then mixed with a hydraulic binder.
After being conditioned, the waste – in the form of metal containers, big bags of rubble, metal drums and solid metal components – is placed into disposal cells excavated into the clay. An opening roof is erected over disposal cells while they are being filled, to protect against rain. The clay soil’s retaining properties ensure that any residual long-lived radioactive atoms will be durably contained. Water quality is monitored while the site is filled. This monitoring will continue during the subsequent monitoring period, pending the return to natural background radioactivity levels.
The disposal cell geometry had to be changed in order to cope with predicted greater waste volumes (35,000 m3 per year). The ground at the repository has been excavated in order to accommodate the additional volume.
© ANDRA ©
The VLLW waste repository in Morvilliers is filling up more rapidly than originally planned. Current predictions point to a volume of 762,000 m3 by 2020 and 1,300,000 m3 by 2030. This increase is partially attributable to the dismantling of decommissioned basic nuclear installations, such as the Siloe and Melusine research reactors in Grenoble.
Several options for increasing waste disposal capacity are possible: expanding capacity at the facilities in Morvilliers; creating a new VLLW repository; and creating in situ repositories for certain waste at dismantled facilities. Certain VLLW waste could also be recycled or managed differently, for example, by compacting crushed rubble in VLLW disposal cells.
ANDRA video To protect the planned disposal cells at the CIRES repository, ANDRA has developed the Prémorail opening roof, featuring a metal structure mounted on rails.
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