ALARP risk criteria

In the nuclear energy industry, the scope of risk criteria includes the whole range of risk criteria from societal and individual risk, off-site radioactive release, reactor core damage accident and lower level criteria to mnnerical criteria used in various risk-informed applications. Risk criteria have variable status in different coimtries strict regulatory limits are defined in few coimtries, while indicative target values are used in most coimtries. The ALARP principle is sometimes applied, involving a risk criterion with a limit and an objective. 

A decision maker could utilize this qualitative assessment along with the quantified risk measures based on probabilities to evaluate how confident he can be about the risk measures. When e.g. an ALARP decision criterion is applied for evaluating the risk acceptability, the broad qualitative assessment guides the decision maker in establishing that the risk is positioned in a given area. 

The regulatory environment is changing in Victoria with introduction from March 2000 of the Major Hazard Facilities Regulations, based on the Seveso II Directives. These are expected to flow on to the other states considered in this chapter. The key requirement of these regulations is the preparation of a Safety Case, which must demonstrate, among other requirements, that the risk from the new plant has been reduced to as low as is reasonably practicable - ALARP . The plants will incorporate a number of design features intended to reduce the risk from the facilities and demonstrate compliance with this criterion. 

Assuming, for the sake of argument, that the scenario is sufficiently serious as to involve two fatalities, then any proposed further risk reduction would need to be assessed against the ALARP principle. Assuming cost of a 2,000,000 per life saved criterion then the... 

Since this exceeds the criterion mooted in Section 2.2, ALARP could be argued to be satisfied without the additional risk reduction. 

Figure 21.1 shows the relation between the acceptance criterion and the SHE goal. Those combinations of frequency and consequence that were denoted high represent a risk that falls above the acceptance criterion. A medium risk of accidents falls within the ALARP region, i.e. between the acceptance criterion and the goal. ALARP expresses that the risk level has been reduced as far as reasonably practicable and that no further cost-effective measures can be identified. Only an accident risk below the SHE goal is denoted low . 

In the range between the acceptance criterion and the goal, the risk should be as low as reasonably practicable (ALARP). 

Calculations of the total recordable injury frequency rates for the new and the reference platforms showed a small decrease for the new platform. It was concluded that the acceptance criterion was met. The analysis, however, revealed a number of activities where an increase in the injury frequency of more than 20 per cent was expected. The ALARP principle called for actions to reduce the risk of accidents in these activities in particular. They included ... 

The second major issue raised in this paragraph is to do with the word unacceptable . If risks are to be categorized for acceptability then some objective criterion is needed. Most companies use a simple risk matrix, such as that shown in Chapter 1 to determine which hazards are acceptable, and which are not. A more sophisticated approach is to use the ALARP concept. 

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