The future is here9 May 2017
It was not so very long ago that virtual reality, drones, and devices communicating with each other would have been regarded as concepts more suitable for science fiction novels than for actual everyday use. The concepts are no longer in the realms of fiction, but are solid fact. Areva NP makes significant use of these in operations and maintenance. Frederic Lelievre, SEVP Sales, Regional Platforms and I&C describes the activities that Areva is involved in.
There are several issues that the nuclear industry faces with regard to O&M. These summarise as needing to meet increasing standards of safety at a competitive price. There is strong competition with other energy sources, and nuclear utilities are trying to improve their competitiveness by reducing the cost of maintenance, increasing the plant availability, increasing the life time of the plant, protecting equipment and the workforce, and reducing costs. It is critically important that nuclear power plants reduce their day-to-day operating costs and increase the value of the asset.
In the USA in particular, there is incentive to extend periods between outages and to extend the operating life of the reactor, in order to increase availability and hence reduce operating costs.
There are a number of things one can do to improve reactor availability. Fuel cycle management can increase the fuel lifetime, which will allow longer fuel cycles, while reducing outage duration also increases reactor availability.
Containing and reducing maintenance costs for nuclear power plants can be achieved by improving equipment reliability through very precise equipment monitoring, predictive maintenance, and operational excellence.
Areva NP has undertaken work to:
- Improve fuel with the objective to provide longer and more flexible cycles.
- Provide equipment with optimised lifetime.
- Optimise existing components.
- Work with nuclear power plants using big data to optimise maintenance programmes.
- Online monitoring of equipment to improve predictive maintenance.
- Optimisation of operation durations.
- Improve reliability of operations.
- Improve field workers’ safety and security.
Technologies to enhance O&M
Areva NP is developing a number of technologies to reduce costs and improve duration and reliability of operations. These include:
Augmented/mixed and virtual reality
Areva NP has adopted a number of fixed and mobile virtual reality tools. These tools simulate scenarios, and place designers and operators in realistic 1:1 scale interactive environments. These consist of immersive rooms, headsets, and “serious games.” Areva has developed a 3D real- time simulator for glovebox work, and a 3D radiological measurement sensor. The tools can be used to validate the ergonomics of certain workstations and the feasibility of a number of intervention scenarios.
Through its virtual reality project, Areva NP is pursuing the introduction of digital technologies at the heart of its reactor design and maintenance activities.
The virtual reality technologies developed offers users full-scale 3D visualisation of systems and components, and the ability to move around immersed in the technical environment. This system is currently being used to the ASTRID Generation IV reactor design pilot project with the French Alternative Energies and Atomic Energy Commission (CEA). Areva is currently evaluating other potential activities, including steam generator replacement projects on the EDF reactor fleet.
Lou Martinez Sancho, Director of Innovation for Areva NP, said: “Virtual reality has multiple benefits for our business, from designing and building our plant and workshops through to operating and decommissioning facilities. Among the benefits is the fact that it makes it easier to prepare intervention scenarios and train operators in a realistic environment. This reduces the risks and costs associated with many operations.”
Augmented reality enables the field worker to call an expert at a distance via multimedia content. This can include video, and it is particularly useful when it comes to preparing for an outage. By using simulators, the field worker can be thoroughly prepared before the outage, thus minimising the amount of time required. Reducing outage time not merely improves the availability of the plant, but it also reduces the amount of time the field worker spends in a hazard zone, thus reducing the radiation dose the employee receives, and hence improving safety.
The field worker can access the right documentation and information at the place of operations, eliminating the need for the worker to leave the place of work, thus saving on time.
Digital training can be carried out through virtual reality, as part of the preparation for work to be carried out. This reduces the time spent on site, and it also provides an in-situ reminder of activities that still need to be accomplished. It helps prepare the field worker, and it reduces the likelihood of on-site problems.
Internet of Things
Areva NP has developed systems using The Internet of Things (IoT) technologies and communication protocols to enable optimisation of the plant. Improved communication technologies has enabled remote monitoring, and wireless technology enables sensors to be placed without the need for cabling.
The reduction of cabling requirement results in fewer design issues with cable path layout, and there is less likelihood of damage to cables interfering with plant operations.
It is possible to provide increasing levels of digitisation on old plants. For example, putting sensors on valves and ensuring that information from the valves is communicated to the rest of the plant, ensuring optimisation of operation.
Areva NP also arranges for the collection of historic data from power plants. It can then use this collected data to assist in predictive maintenance. Cyber-security is an issue for these, and Areva NP is very sensitive about the issue. It is very careful to ensure the best protections are in place.
Robotics and drones
Robotics and drones enable remote access to hazardous zones, and access to remote zones and areas that are difficult to access.
Drones are used to go into irradiated zones, into piping, and underwater. Drone use in irradiated zones means that field workers do not receive harmful dosage, and thus provides radioprotection to the workers. Drones are also better able to access difficult locations, and provide better cost-logistics. They are also used in primary loops.
Robots with appropriate sized tools are increasingly being used to carry out maintenance work in hazardous zones. This increases safety for field workers.
New Areva also uses inflatable articulated arms for inspections. This enables inspection into zones where humans cannot go, and it prevents field workers from receiving dosage, thus providing radioprotection.
Developments in mobile communication technology has enabled a field worker to make use of a mobile virtual office or deported office. It can also enable the secondment of new technologies to facilitate teamwork during a complex intervention.
The mobile solution allows the operator to operate in the most efficient way without papers. Minimising the amount of paperwork involved at the site improves safety and speeds up work. Data can be transmitted from the site of operations to a remote location, enabling analysis to be carried out away from the site. This reduces the time technicians need to be on site, thus improving safety.
Areva NP has been developing new materials for use in nuclear power plants. This includes developments in polymer and other innovative coatings, providing lifetime extension to equipment.
Material mitigation can increase the life of equipment. In ageing US nuclear power facilities, one of the biggest expenses is the replacement of components due to wear and degradation, such as the reactor vessel closure head. By proactively peening such components, utilities extend the life of reactor components, in turn extending the life of the reactors.
Rather than allowing operational stresses to create multiple, random fractures on a component’s surface, cavitation peening creates compressive stresses on the surface of the material in a controlled manner, resulting in a texture similar to a golf ball’s surface, but with much smaller indentations.
Areva NP’s peening process uses submerged, ultra-high-pressure (UHP) water jets to work the surfaces of reactor vessel components. The high-pressure water flow creates cavitation bubbles. As these vapour bubbles collapse on the component’s surface, shock waves travel into the material and create compressive residual stresses, which improve fatigue life, damage tolerance, and enhanced resistance to corrosion. There are a number of benefits of cavitation peening, including:
- Stopping primary water stress corrosion cracking (PWSCC).
- Eliminating the risk of emergent reactor vessel closure head (RVCH) nozzle and reactor vessel bottom mounted nozzle (BMN) repairs.
- Lower cost than repair or replacement.
- Both outer and inner diameter nozzle surfaces are mitigated.
- There are additional schedule and cost savings when In-Service Inspection (ISI) and surface mitigation scopes are combined.
- No harm to component surfaces.
- The process uses only water from the reactor cavity. There are no foreign matter exclusion concerns.
- It does not leave abrupt edges between peened and non-peened regions.
Since Areva’s NP UHP cavitation peening operates at a higher pressure than that of many other providers, the process achieves higher depth of compression and faster work completion, leading to a lower overall implementation schedule. In addition, the UHP cavitation peening mitigation of a group of reactor vessel nozzles is often less expensive than nozzle repairs.