ABSTRACT
This chapter focuses on different types of rules that are important for operational decision-making. It begins by looking at the background to the quality systems approach and its weaknesses as well as its strengths for management of operational safety in complex systems. The chapter explores the way in which rules both constrain and support operational managers when making safety-related decisions. This is essentially the view of the quality management theorists whose influential approach now forms the basis of regulations, industry standards and company procedures which all focus strongly on compliance with rules as a means of managing and controlling operations to ensure safe performance. Safety decision-making at the nuclear power station was strongly influenced by compliance with such an operating envelope defined in what were called Station Operating Instructions (SOIs). SOIs are formulated by engineering considerations outside the operational managers' direct experience and knowledge.
