Legacy Support for Safety Systems

Ultra Electronics, Energy has been involved in identifying replacement solutions for Civil Nuclear operators throughout the UK. Such replacement systems are subject to the full rigour of modern standards, which were not in place when the original C&I infrastructure was put in place. In many cases the underlying architecture of the original system is not compatible with modern standards either in terms of redundancy, diversity or product integrity. This makes like-for-like replacements unsuitable and leads to significant difficulties in establishing the necessary architecture and safety requirements for replacement solutions.

The following issues are common challenges:

  • A significant proportion of the components in use within current systems are now obsolete.
  • While not subject to lifetime limits, component ageing is usually a concern, particularly in the context of station lifetime extension programmes.
  • Design disclosure from COTS suppliers for replacement equipment is often inadequate to provide a robust safety justification based on equivalence.
  • COTS products are subject to peremptory change and have an uncertain lifetime.
  • COTS products sometimes fail to provide the required accuracy and electrical characteristics.