Safe disposal of nuclear waste in bedrock
Posiva Oy takes care of the research, development and design work of its owners' disposal of spent nuclear fuel and is responsible for the construction and operation of disposal facilities. Ensuring the long-term safety of the waste has required studies, in which Elkome has been involved in supplying measurement systems and sensors.
Geological isolation of nuclear waste
The nuclear waste in Posiva's final disposal solution is safely disposed deep in the bedrock. According to research, this is the best way to isolate high-level nuclear waste from the biosphere, i.e. the human habitat. Posiva is currently building an encapsulation facility and an underground disposal facility in Olkiluoto in Eurajoki. The facilities are planned to be commissioned in the mid-2020s.
Ensuring long-term safety
The waste in the disposal solution is packed in gas- and water-tight, durable copper-cast iron capsules. The capsules are placed at a depth of about 430 meters in the rock, lined with bentonite, where they are separated from people and remain sealed without care as long as their contents could cause significant harm to living nature. Ensuring safety requires research and, for example, for performance analysis of bentonite clay, Posiva asked Elkome for a proposed measurement system including the necessary measuring equipment and sensors.
Measurement and analysis of the development of concrete clay
For the performance analysis in question, a 9m x 2m x 2m test tunnel was built, under which there was a test hole with a diameter of about 1m and a depth of 3m. Earth pressure and moisture sensors installed in the test hole measured the development of the bentonite clay as moisture causes the bentonite clay to expand. During the measurement, the sensors were able to withstand a pressure of 100 bar, and they were not allowed to be damaged during the measurement due to the influence of salty groundwater. The challenge of the measurements was also increased by the long 8-9 months spent on continuous testing.
Measurement system based on dataloggers and geotechnical sensors
Datataker DT80 dataloggers were chosen as the data collection devices of the measurement system, which made it possible to connect various sensors to the programmable sensor inputs. Geosense's earth pressure sensors and Vaisala's humidity sensors were chosen as the sensors for the measurement system.
- Elkome was the only system supplier that knew how to propose a suitable measurement system solution for the implementation of performance analysis. We are very satisfied with the guidance and advice we received in planning and implementing the system, thanks Posiva's Product Development Engineer Mika Niskanen.
"Elkome was the only system supplier that knew how to propose a suitable measurement system solution for the performance analysis. We are very satisfied with the guidance and advice we received in the design and implementation of the system."
Product Development Engineer Mika Niskanen, Posiva Oy
