With rapid advances in digital technologies, smart digital devices such as smart sensor transmitters, electrical protective devices and variable speed drives, are increasingly used at many nuclear power plants – even if they were not initially designed for nuclear-related purposes. The safety aspects of the use of such devices were discussed at a meeting in Vienna at the end of February with the participation of experts from around the world. The objective of the meeting was to establish guidance on the selection and evaluation of smart devices to be used in systems important to the safety of power plants – which will be the first ever IAEA safety report on the subject, to be published later this year.
Old and obsolete equipment in power plants is more and more often replaced with smart devices, which are electronic devices generally connected to other devices or networks via different communication protocols and are able to operate to some extent interactively and autonomously. This can include devices with properties of artificial intelligence. However, the nuclear market is too small for the development of customized smart devices specifically for power plants; therefore, operators turn to devices initially developed for other market segments and certified by non-nuclear authorities. They may require extra measures to be used for nuclear power plants.
“Smart devices can be used in equipment or systems to increase nuclear power plant safety and reliability, enhance safe operation or improve various functions. However, if not properly selected and qualified, they may potentially introduce new hazards, vulnerabilities, and failure modes,” said Alexander Duchac, Nuclear Safety Officer at the IAEA, in charge of the report. “It’s a potential issue for both operating and new nuclear power reactors.”
Operators have the legal obligation to follow regulators’ safety recommendations, but regulators do not normally have access to the design information of equipment to make an informed decision on the devices’ safety. The equipment qualification is very often almost impossible without cooperation from the vendor, who tends to protect the intellectual property of commercial development processes, Duchac explained. The participation of 43 smart-device designers and developers, users and regulators from 20 countries in the meeting demonstrates the importance of the subject, he added.
Moreover, operators often lack guidance on how to provide sufficient information to the regulator under such circumstances. It is against this background that the experts who participated in the meeting to produce the report are considering best practices from around the world on demonstrating that proposed devices are suitable for application in nuclear power plants.
“There is a direct link between the technical and safety objectives as set by regulators, and the operational costs of qualifying and using smart devices. We need to find an appropriate compromise to ensure the continued safe and economically sound operation of our plants,” said Alexander Wigg, instrumentation and control engineer at EDF in France, who was a participant at the five-day meeting.
Furthermore, the practice to assess the safety of these devices for use in the nuclear industry differs among countries, and building a consensus is not an easy task. “For us, IAEA guidelines in this matter are important, as we are developing our regulatory framework,” said Ionita Madalina, Nuclear Safety Adviser at the National Commission for Nuclear Activities Control (CNCAN) in Romania.
Currently, there is insufficient guidance on the use of smart or intelligent digital devices in nuclear-related systems, said Greg Rzentkowski, Director of Nuclear Installation Safety at the IAEA. “It is our task to provide assistance to change that and to assure design safety.”
The IAEA safety report intends to provide a common technical basis for all countries. The upcoming report was prepared with the contribution of 43 regulators, operators, designers of smart devices and developers of other internationally recognized safety standards from 20 countries. It will contain a model of how to design, select and evaluate candidate smart devices for their safe use in nuclear safety systems, including instrumentation and control, electrical, mechanical and other areas.