Hydrogeological data analysis for SKB’s nuclear waste disposal research
80% of local residents support the spent fuel repository
SKB, Swedish Nuclear Fuel and Waste Management Company, is responsible for the safe and secure disposal of Sweden’s radioactive waste originating from nuclear power stations, hospitals and research laboratories. Applied Industrial Systems (AIS) has been working with SKB since 1988.
Disposal of nuclear waste must be carried out in a safe and responsible way, to protect the environment and mankind. In SKB´s opinion this is one of the largest environmental protection projects in history. Constructing a final repository for spent nuclear fuel at a depth of about 500 metres is today considered to be the safest solution. The spent nuclear fuel will be encapsulated in robust canisters with nodular cast iron and copper and then embedded in a buffer of bentonite clay at a depth of about 500 metres. The bedrock and the great depth help to isolate the spent fuel from human beings and the environment for at least 100,000 years. This means that the canisters and the buffer will to function for a very long time.
“AIS have helped us to build a world first with this monitoring programme, supported by a bespoke SCADA system that is highly flexible and reliable. They have been instrumental to the success of the spent fuel repository initiative and continue to be a very important technology partner to our company.”
Consultant at SKB
KEY SYSTEM BENEFITS:
- Flexibility to acquire a range of data in real time from a wide range of online and offline sources and successfully integrate both variants
- User friendly customisable reports to illustrate long term hydro-geological movements can be accessed via an online portal
- Highly accurate system compensates for instrument setting variance and can correct sensor drift
- Data anomalies are captured and explained to users, allowing results to be interpreted contextually
- Captured data can also be quality graded to ensure that any data gathered from unreliable instruments is excluded from reporting – a very important system safety feature
- Allowed SKB to secure long term public support for waste management proposals.
SKB first engaged AIS in 1988, to work alongside them with the long-term safety monitoring of ground water at the two candidate sites; Forsmark and Oskarshamn. For compliance purposes, SKB needs to show that if they were to construct a final repository at one of these locations, there would be no risk of water contamination and that the safety of remaining substances would be maintained for at least 100,000 years. SKB has been able to demonstrate this through a monitoring programme conducted over three decades, using data captured and analysed by a web-based SCADA system developed by AIS.
SCADA to support hydro-geological modelling
AIS designed a highly customised, real-time, asynchronous SCADA monitoring system to enable the collection, viewing, aggregation and modelling of hydro-geological data in support of SKB’s proposals.
Buried deep within the bedrock, a variety of transducers and sensors are used to record a wide range of measurements, including groundwater levels and water pressure, water temperature at various depths, seismic activity, electrical conductivity and groundwater flow. From this, a detailed understanding of how water travels within the bedrock – and therefore the environmental implications of the repository – could be modelled.
Schematic drawing outlining how nuclear waste will be handled by SKB
How the SCADA system works
The AIS/SKB SCADA system has the flexibility to acquire a range of data in real time and generate customisable reports that illustrate long term hydro-geological movements, each of which can be accessed via an online portal.
It has been designed with a range of feature/benefits as follows:
- The system captures data from a wide range of online and offline sources successfully integrating both variants.
- Some of the data loggers are located deep within underground bore holes and may have been monitoring conditions since 1991. This data is combined with surface readings, some of which are taken manually by field researchers, during short time tests. Once aggregated, researchers have a complete understanding of water movements.
- Raw values from data loggers are transferred to engineering values by applying calibration calculations. These may vary over time as instrument settings alter and the system is capable of correcting sensor drift.
Comments explaining anomalies within the data can be captured and displayed on graph plots. Since data is being generated from different instruments – known as channels – it was important for SKB to have the ability to track discrepancies in multiple ways. This means that a comment about recorded data will always be transferred across to different reports – according to the channel from which it was captured – so that results can be interpreted contextually.
- Data can also be graded with a ‘zero-centred’ quality rating ranging from -2 for rejectable data, to +3 for the highest quality. This ensures that any data gathered from unreliable instruments is excluded from reporting. Currently quality ratings are added manually, but in the future, SKB plans to automate this process, using statistical modeling to assign the values. During reporting, filters can be applied to all the data, giving SKB the ability to hide unreliable sources and exclude information below a standard quality level.
Given the stringent safety requirements SKB needs to comply with, these are very important system features.
Sample groundwater monitoring data set
Public opinion in favour of waste management
As part of their task, SKB conducts an annual opinion poll, to measure the degree to which local residents would be in favour of the project, should it go ahead in the future.
In the latest polls, 80% of residents said they supported the construction of the spent fuel repository in Forsmark, in the municipality of Östhammar.
This demonstrates that the data collection and SCADA monitoring programme developed by AIS, has been successful in enabling SKB to clearly communicate the extent of risk mitigation being undertaken and the potential risks presented to residents. Although the project has not yet been awarded building approval, the high degree of public support means that SKB can retain its operating license and continue its important environmental research activities.
For more information about SKB visit https://www.skb.com/
AIS added value as control system integrators
- Critical national infrastructure specialists and approved Siemens WinCC OA SCADA experts
- Ability to integrate multiple, disparate control systems and provide a single, intuitive user interface that meets the latest cyber security and human factors development requirements
- Experienced at developing SIL2 life safety systems
- Collaborative design approach ensures high user acceptance with projects delivered on time and within budget.