Nuclear Power Plant Structural Health Monitoring
Over the last few years, the nuclear power industry has developed dramatically in order to respond to a worldwide increasing demand for economic and sustainable energy. New nuclear power stations set the standards for safer and longer lifetime (60 years) plants, requiring the highest level of monitoring system based on reliable and durable sensors. Therefore, the monitoring system offers quite unique challenges that the Testindo Group has addressed successfully since 1960.
The Testindo Group’s instrumentation is used for real-time monitoring of soil/structure of the plant such as in reinforced grounds (diaphragm walls) under the buildings, in pipelines and in cooling towers. This is highly critical for the internal concrete containment enclosing the reactor, in order to prevent any radioactive particles to escape into the atmosphere.
Indeed, different threats might affect the function of the containment building:
- Concrete deformation due to internal swelling mechanisms
- Rebar corrosion
- Losses in the pre-stressing due to concrete creeping
- Collapse of soils under the raft of the nuclear island, which can have consequences on the displacement of the structure and load distribution over the raft
- Seismic activity, which can compromise structures
- Increase of pressure / temperature inside the building due to accidents (meltdown of the reactor, pipeline leakage, etc.)
The Testindo Group’s monitoring system gives real-time data on the condition of the concrete containment and its steel liner, ensuring the leak-tightness, using traditional sensors (vibrating wire) and fiber optic sensors.
By studying different parameters, the In-Service Inspection Instrumentation (ISI) allows the evaluation of the mechanical behaviour and integrity of the containment at different phases:
- During construction
- During the acceptance (pressure) test and periodic tests during the life of the plant
- During the operating time of the plant
Benefits of the Testindo Group's Integrated Nuclear Power Plant Health Monitoring Solutions
1 - Integrated solutions The Testindo Group provides Integrated Structural Health Monitoring Solutions for nuclear power plants, based on advanced fiber optic technologies and conventional sensors. All sensing technologies are seamlessly integrated into a single database and user interface.
2 - Provide important data about the structure's behaviour Structural Health Monitoring aims to provide relaible data on foundations, structures and internal containment building. One of the most important aims of a monitoring system is to compare data acquired from instrumentation with expected design values obtained from numerical analysis. Records obtained from nuclear power plants instrumentation are, therefore, crucial to increase the knowledge about the buildings.
3 - Keep environmental effects under control Earthquakes, ground movements, reactor meltdown and pipeline leakage can occur, and may have potentially significant impacts. The Testindo Group’s monitoring system is used to measure the response and check the integrity of the building during and after these events.
4 - Reduces costs The implementation of a Testindo Group monitoring system with high accuracy, reliability and robustness can decrease the insurance premiums allocated for refunding possible liabilities and damages on people, properties and environment caused by any major accidents.
5 - Help preventive and proactive structure management Allows the control of budgets and unforeseen unavailabilities:
- Diagnose and forecast the mechanical integrity of containment and, therefore, to prevent and anticipate potential failures and unavailabilities
- Plan maintenance operations due to unexpected structural degradations
- Have a realistic view of the residual life of the structure and identify the needs for investment, if necessary
- Justify the extent of the plant lifetime, if needed.
6 - The Testindo Group: a dependable partner for instrumentation project management The Testindo Group will support the owners in all phases of a project, from system design to installation, commissioning and training. Through the experience and commitment of the Testindo Group, any monitoring needs will be met. The Testindo Group has been instrumenting critical structures, including dams and nuclear power plants, for more than 60 years. It's worldwide network of system integrators provides a competent local support for any project. All the systems come with a 10 year warranty on the availability of spare parts.
Solutions
The following packages are the most widely used for nuclear power plant monitoring. However, each project has specific requirements and needs that can be addressed by a tailored system. The Testindo Group has developed a 7-step methodology to design and implement an optimal SHM system for any nuclear power plant.
- Local Strain: Concrete embedded extensometer
- Distributed Strain: Distributed deformation of steel liner / concrete structure
- Average Strain: Long base extensometer
- Displacement: Joint openings, existing crack opening
- Distributed Temperature: Temperature distribution in concrete
- Local Temperature: Air / Concrete temperature
- Tilt : Global tilt / Rotation / Verticality of containment walls
- Load : Force in pre-stressing cables
- 3D Movement: Global movements of the building
- Rebar corrosion
- Pipeline Corrosion: Water cooling pipelines
- Pipeline leakage: Water cooling pipelines