Safety

Quantitative Risk Assessments Are Useful but Have Limitations

This paper discusses and demonstrates the limitations of quantitative risk assessment (QRA) with respect to the usefulness of the concept in managing day-to-day and emerging risks as well as the effect of change.

IAEA experts inspecting damage at Fukushima Daiichi Nuclear power plant.
IAEA experts inspecting damage at Fukushima Daiichi Nuclear power plant.
Source: SPE 220333.

This paper discusses the limitations of quantitative risk assessment (QRA) with respect to the usefulness of the concept in managing day‑to-day and emerging risks and the effect of change. The current use of QRA creates a mismatch between the management of risks on paper and real-world situations. This paper proposes updating QRA by transforming it into an active management tool linked to proactive management of risks through bowtie and similar models.

Challenges of QRA

The purpose of QRA is to establish a number that represents the likelihood of incidents and to undertake measures that mitigate risk to within an acceptable level. In a range of industries, it can be observed that what are presumed to be very unlikely events, based on QRA reports, nevertheless appear to occur with regularity.

Major events, such as refinery explosions and rail fires, in theory, should occur so rarely that a single instance should not be expected.

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