AAOM Handbook

Fixed Interval replacement may be appropriate during the high risk period. • Constant risk probability over time or operation (random). This type of distribution is typical of steady state process operation where there are many independent potential initiators of an unwanted event. This type of distribution is also typical of situations where human behaviour plays a significant role in the hazard release mechanism, (e.g. stress caused by incorrect use or operation of the process or equipment). • Increasing risk probability (either linearly or exponentially) over time or operation (wear out). This type of distribution is typical of the situation where an element of the process is subject to fatigue, corrosion, wear or fouling, and the design allowance for these actions is consumed. • The Functional Life of the process (related to the time period for which risks related to the process may persist - which may extend beyond the operating life of the process. For example, a tailings dam must contain waste long after disposal into the dam has ended), • The probable unwanted event (a combination of the Serviceable Items, risk types and hazards) • The potential consequences of the unwanted event (safety, environment, health, revenue, costs, reputational, regulatory and social impacts), • The level of exposure that is probable if the unwanted event occurs. The level of exposure will be affected by issues such as; the capacity to mitigate the consequences by using stockpiles or extra capacity, the capacity of containment systems, or the number of people in a potential area of exposure and the proportion of time they are there. • The shape of the probability distribution of the unwanted event over time or operation. • Whether (and how) the development of the unwanted event is detectable. • The current situation and consequent risk level (this is particularly relevant when evaluating Service Strategy options for unwanted events with a very long and predictable development period – e.g. corrosion, obsolescence). • The Warning Interval (or probability distribution of intervals) between the indication of a developing unwanted event or consequence and the ultimate occurrence of unwanted event or consequence. Risks can be found around every process. Whether or not a risk is realised might depend on any of the following elements of context for the process; • capability of people for their role, • behaviours, symbols and systems in the social environment, • induction and training, • physical environment, • design of processes, work, plant and equipment, • choice of materials, operating limits, techniques and practices, The characteristics that are most significant in the consideration of potential Service Strategies are: