Due to the process of radioactive decay, the impact of short-lived radioactive waste is negligible after 300 years.
However, the LILW-SL waste may also contain long-lived radionuclides in very small quantities, limited to ensure a negligible impact of these radionuclides may have in the future.
The maximum activities allowed to be disposed of in the CSA are fixed for certain radionuclides by technical requirements issued by the Safety Authority. This is the case for example of tritium, carbon 14, chlorine 36 and other radionuclides. The total alpha activity inventory at 300 years after the closure of the CSA is also limited.
Origins of waste
The waste comes mainly from the nuclear power sector represented by three giant nuclear operators that are EDF, CEA and ORANO (formerly Areva). However, the CSA also disposes of non-nuclear waste from hospitals, research laboratories or other industrial activities.
Below are several exaples of the LILW-SL waste disposed of at the CSA :
- Technological waste;
- Process waste;
- Heavy maintenance waste;
- Decommissioning waste.
Technological waste is generated during maintenance or repair works. It comes from rooms, laboratories and worksites located in a controlled area. These wastes are diverse in nature (metal, filters, cables, rubble, plastic, glass…)
Decommissioning waste is the result of decommissioning and dismantling of nuclear facilities. They consist mainly of scrap metal, rubble, earth and sludge.
Process waste results from the cleaning of ventilation and primary or secondary water circuits. These are, for example, water filters, air filters, ion-exchange resins, evaporator concentrates, sludge from sedimentation tanks, etc.
Heavy maintenance waste comes from replacement and exceptional maintenance operations, such as vessel heads, primary pumps, parts of fuel assemblies.
A CSA disposal vault is intended to receive radioactive waste packaged in containers that can be very different from each other. These packages may have a cylindrical, cubic or parallelepiped shape, variable dimensions (16 types of packages are specified by Andra, see Box 1 and 2), different container compositions("Concrete" container is qualified as sustainable or durable whilst "metallic" container is considered perishable) and also different diverse types of emplaced waste (heterogeneous waste, homogeneous waste, steel, concrete, plastic, resin, etc.).
Perishable packages: metallic drums (100, 200, 450 and 870 l) and boxes (and 10 m3, metal ingots from fusion of metallic waste)
Non-perishable packages: 5 and 10 m3 concrete boxes, various types of concrete drums.
The waste package, whether perishable or non-perishable, containing homogeneous or heterogeneous waste, is always grouted Inside by mortar.
Waste conditioning at the CSA
Waste package grouting (cementation) unit
The purpose of the grouting unit is to block by mortar all bulk radioactive waste contained in 5 and 10 m3 metal containers so as to form a solid and non-dispersible, radioactivity-confining 5 cm thick matrix around the waste. The mortar is specially chosen and qualified for its performance in the containment of radionuclides and the mechanical strength of the package.
Waste package compaction
The purpose of the compaction unit is to compact 200 L drums filled with "soft" radioactive waste; the waste pucks thus obtained are then cemented in a 450 L drum with hydraulic binder.
Generally a 450 drum L will contain an average of 4 -5 pucks.