DIAGNOSTICS & INSPECTION | UPGRADING RADIOLOGICAL SURVEILLANCE
Upgrading surveillance
Many of the control and monitoring systems still in use at nuclear plants today were never designed to support the full operational lifespan of the facilities they serve. What are the impacts of this harsh reality and how can it be overcome?
By Gary Bradshaw, Director, Omniflex
disruption, particularly in radiation-controlled areas. For example, installing new network cables involving digging a cable trench is a major undertaking as all the materials that have been disturbed must be radiation tested and carefully disposed of as hazardous waste. Risk assessments and method statements must also be written up to determine how the new trench will impact radiation protection across the site, making the process even more complicated. This makes it prohibitively time and cost intensive in most scenarios. The challenge is therefore not simply to modernise, but to
The UK’s Sellafield needed a way to decouple RSS functionality from DCS platforms. Source: Sellafield Ltd
IN THE 1980S AND 1990S, distributed control systems (DCSs) were typically installed as integrated platforms that incorporated radiological surveillance functionality in the same hardware and software environment. At the time, this made sense. Systems were engineered to the standards of the day, and expected facility lifespans were significantly shorter than those now anticipated. However, nuclear facilities are routinely expected to operate for at least 80 to 100 years. That fundamental shift has exposed the limitations of tightly coupled control and monitoring architectures, particularly where safety-critical radiation surveillance is concerned.
Why separating DCS and RSS matters Over time, industry best practice has evolved to recognise that DCSs and radiological surveillance systems (RSSs) serve very different purposes. A DCS is designed to manage and control industrial processes whereas an RSS exists to protect people and the environment. Separating these systems and ensuring they rely on
different hardware and software significantly reduces risk and prevents faults. In the UK, for example, this separation is now a standard requirement for new nuclear installations and upgrades across all the country’s nuclear sites. Early detection of radiological anomalies and the ability to
trigger alarms and evacuations quickly are critical. Therefore, these functions must remain operational regardless of what is happening elsewhere in the control architecture. However, one of the biggest challenges facing nuclear
operators is that, while legacy DCS and RSS platforms are becoming obsolete, the nuclear facilities are remaining operational far beyond their original expected service lives. In fact, many nuclear installations and on-site buildings are expected to remain operational for decades still to come, making long-term technological support non-negotiable. Replacing an obsolete system in a nuclear environment is never straightforward. Wholesale replacement of sensors, cabling and field equipment introduces cost, risk and
58 | April 2026 |
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do so intelligently by reusing existing infrastructure wherever possible while bringing systems in line with modern standards.
Designing for flexibility and longevity This is precisely the challenge the UK’s Sellafield set out to address in the mid-1990s. At the time, many of the radiation protection monitors in use were still current models, but operators nonetheless needed a way to decouple RSS functionality from DCS platforms. A range of modular systems were deployed to provide a flexible platform capable of interfacing with a wide range of radiation detectors, regardless of manufacturer, while remaining open to future technologies. These systems support diverse network types, including ethernet, radio, LoRaWAN, GSM, and Conet, a proprietary technology which allows operators to reuse existing cabling for modern digital communications, bypassing the need for expensive rewiring projects. This flexibility reduces both cost and risk, while allowing the RSS to evolve independently of the primary control platform. Over the past 30 years, this approach has proven its value
as RSS installations continue to provide reliable real-time and historical data, supporting both operational safety and regulatory compliance. In nuclear environments, change itself is a risk factor. Every
cable replaced, every sensor removed and every interface modified must be justified, documented and validated. Therefore, the ability to upgrade monitoring systems without disturbing field infrastructure is a major advantage. Effective modernisation is not about wholesale
replacement. It is about designing systems that can evolve, accommodate legacy equipment and remain supportable for decades. In nuclear environments, that approach is both good engineering practice and essential to maintaining safety and public trust. As the industry continues to modernise, success will depend not on how quickly new technology can be deployed, but on how carefully it can be integrated into the complex, long-lived systems that nuclear facilities rely on every day. ■
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