More recyclables – less waste
To support efficient and sustainable decommissioning, EnBW has established a material processing center in both Neckarwestheim and Philippsburg. During material processing, a specific portion (see below) of the dismantled material is decontaminated of its residual radioactivity. This increases the proportion of recyclable materials while simultaneously reducing the volume of radioactive waste to a minimum. In doing so, we are complying with the requirements of the German Circular Economy Act to return as many recyclable materials as possible to the material cycle. Another advantage of these facilities is that they significantly reduce the need for transport related to decommissioning. Waste processing is therefore worthwhile - even if it is only practical and necessary for a small portion of the total decommissioning volume of a nuclear power plant. Processing is thus an integral part of the decommissioning process.
Both material processing centers, which are nearly identical in design, are operated by Gesellschaft für nukleares Reststoffrecycling mbH (GNR). It is a wholly owned EnBW subsidiary with approximately 150 employees.
Basic principle of material processing
Only a very small portion of the total mass of a nuclear power plant consists of radioactive waste. This waste, in turn, can be either contaminated or activated. Contamination refers to a situation where radioactivity is merely attached to a waste material from the outside in the form of radioactive particles. Using appropriate processes, these particles can be removed and separated to such an extent that the remaining material - following the necessary clearances and under constant regulatory oversight - can ultimately be safely returned to the conventional recycling stream. The separated particles, however, follow the disposal pathway defined for radioactive waste.
In contrast to contaminated material, there are also so-called activated components and materials, for example, from the reactor pressure vessel. In this material, radioactivity has penetrated deep into the interior of the respective structure. Such materials can no longer be decontaminated. They are therefore not sent for material processing but are directly classified as low- to medium-level radioactive waste and packaged accordingly for interim and final storage.
All these processes are based on continuous measurement and categorization procedures carried out by EnBW under regulatory supervision.
Thanks to processing: About 99 percent of the total mass is non-radioactive
Overall, material processing helps ensure that, of the total mass from our nuclear power plants, only 1 percent is radioactive waste in the end. At the same time, the proportion of recyclable materials that can be returned to the conventional material cycle rises to up to 98 percent. This conserves resources.
Read more about recycling and disposal here.
Multiple processing and conditioning technologies under one roof
The Material Processing Centers do far more than simply decontaminate dismantled materials. They also employ a range of additional processes and facilities that support the logistics associated with the processing, recycling and disposal of materials.
Residual materials can be loaded into a large band saw using a crane, clamped to the saw table, and then cut. Items that can be cut include, for example, piping, larger container parts (bottoms, lids, shields), cylinder heads, and engine blocks. In thermal cutting, the further cutting of residual materials takes place in a closed steel cabin. The cabin roof can be opened to allow larger parts to be loaded in and unloaded using a crane. Commonly used thermal processes include plasma cutting and oxy-fuel cutting.
Decontamination processes remove the radioactivity that has previously adhered to residual materials. For example, in so-called dry blasting, blasting material (e.g., steel grit) accelerated by compressed air is directed at the surfaces. Adhering particles are thus removed. So-called wet blasting works in a similar way, in which the surface of residual materials is removed using a water jet. Both processes are carried out in closed booths designed for this purpose. The surface material removed during blasting is then collected and placed in designated containers. The resulting water is collected and treated.
After processing, residual materials intended for a clearance measurement are first subjected to a preliminary measurement. If the results show that the materials meet the prescribed clearance criteria, they are transferred through the adjacent material airlock from the controlled area to the measurement hall, where the final clearance measurement is carried out. Residual materials that comply with the stringent criteria and are granted unrestricted regulatory clearance can, following the final measurement, be returned to the recycling stream as valuable materials.
Residual materials that remain classified as low- and intermediate-level radioactive waste must be processed and packaged for government-operated interim storage and final disposal. These steps are referred to as conditioning. For example, mixed waste (e.g., cables, plastics, insulation material, and construction debris) located in so-called compaction drums can be compressed in a high-pressure compactor. Once the waste has been processed into solid compacts, it is packed into standardized, approved containers. This helps reduce the volume.
Clearly defined disposal and recycling pathways
There are clearly defined disposal and recycling pathways for all residual materials and waste generated during the decommissioning process. Before decommissioning material is assigned to a specific category, it undergoes a defined process involving repeated measurement, processing, categorization, and documentation. These procedures are coordinated with the regulatory authority and monitored by an independent third party. EnBW strictly adheres to all legal requirements and proceeds with the utmost care and precision in all processing and conditioning steps.