7.4.1 Purpose and objectives of advanced HSIs

As indicated in the earlier definition, the primary purpose of the HSI is to provide the operator with a means to monitor and control the plant and to restore it to a safe state when adverse conditions occur. The successful accomplishment of this objective will satisfy the five important human performance goals that all contribute to the safe and efficient operation of the plant: (1) reduce complexity, (2) reduce error and improve human reliability, (3) improve usability, (4) reduce operator workload and (5) improve situation awareness.

Achieving these objectives relies heavily upon the most effective information and communication technologies available. These technologies have the potential to improve many of the shortcomings of the old generation of analogue HSIs (that is, ‘hard controls and instruments’, such as buttons, switches and gauges) found in most NPPs. However, such improvements are dependent on a focus on human — factor principles in human-technology interaction. Advanced automation systems are beginning to allow a more dynamic collaboration between humans and systems. We can no longer regard the complex relationship between humans and systems as ‘people versus technology’, which was often the result of the classical function allocation approach. That out-dated approach was based on attempts to implement ‘HABA-MABA (human are better at-machines are better at’) principles derived from Fitts’ List (Hoffman et al., 2002). Rather, it now is more appropriate to focus on the total socio-technical system as a ‘joint cognitive system’. Woods and Hollnagel (2006) and Lintern (2007) describe a cognitive system as one that performs the

cognitive work functions of knowing, understanding, planning, deciding, problem solving, analysing, synthesising, assessing and judging, as they are fully integrated with perceiving and acting. In a particular work environment in the power plant, the entity that performs perceiving and acting functions would be the human agent. This implies that the control room and the entities within it could be characterised as a joint cognitive system that functions in a distributed way and involves relevant parts of the environment, the physical, mental and cultural processes of people, and the technical artefacts. The joint cognitive system viewpoint emphasises the cognitive functions that human operators and technologies accomplish in collaboration. It allows human-factors analysts and designers to analyse the system on different levels of detail, starting from the entire socio-technical system of the NPP, down to specific functions of an HSI that would have the ability to support the operator’s cognitive functions.