10 January 2012
The integrity level of 10-3 (Probability of Failure on Demand) or SIL2 capable for nuclear safety and safety related applications is the highest level yet for smart devices that contain and operated by software or firmware. This qualification was completed after the STA passed both EMPHASIS and separate further assessment by Independent Confidence Building Measures. These are both essential parts of safety case development required by the nuclear regulator in the UK. The EMPHASIS method was developed by the UK nuclear industry through the Control & Instrumentation Nuclear Industries Forum working group to assess a device’s compliance with the IEC 61508 international functional safety standard, along with other requirements specifically relating to the UK nuclear energy industry. It is designed to provide confidence that the firmware or software in these devices meet the required good practice levels of design, testing and production to achieve the integrity levels needed for project applications and reduce the risk of systematic failures. Assessment by the EMPHASIS methodology ensures ‘Production Excellence’ of the device by examining a series of criteria including the company, its core competencies, the tools and techniques used in the design and production of the product and the testing requirements, particularly of the software. The second part of the approval process required by EDF Energy is Independent Confidence Building Measures, which sees different and independent competent individuals or specialists use measurements and techniques, such as static analysis or statistical testing of the device source code, to evaluate the performance of the product against its claims. This determines if a product meets application demands and complies with standard engineering design codes. While additional, specific engineering justification is still required for each application case, having the majority of justification work for “device generic applications” completed significantly reduces project risks while relieving cost and time burdens associated with trying to justify unapproved equipment.The relationship between Moore Industries and EDF Energy dates back to 2002. Cooperation between Moore Industries’ engineering groups, EDF Energy (together with Sellafield Ltd) and specialist consultants Adelard LLP has resulted in a number of research projects including the development of the original EMPHASIS methodology. It has also led to other assessments of Moore Industries products including the 535 controller, TRY temperature transmitter and the SPA2 Site Programmable Alarm trip.
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