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RISK MANAGEMENT


identify those hazards/faults that should be assessed via QRA. Also, the findings must be used within an overall safety justification which pulls together both deterministic and qualitative elements in a manner that is sensitive to their relative strengths and weaknesses.


BENEFITS OF A QRA


Beyond their raison d’être of providing an accurate estimate of risk within a complex facility which cannot be adequately assessed using deterministic means, QRAs present a number of further benefits. They can be used to confirm the validity of your deterministic assessment strengthening your overall safety justification. In addition, it is a very effective tool for comparing the risk profile for various design and/or operational options as part of your risk based decision making process (see article on ALARP in April/May 2012 issue).


LIMITATIONS OF A QRA A QRA is only as good as the input data used. Make sure it is accurate and relevant/appropriate for your specific application and, wherever possible, is based on relevant historical information. It is easy to overly complicate a QRA and go straight in for lots of detail. This is time consuming to do and complex to verify, escalating costs. Where possible, start by using simple, bounding assumptions and only add in more complexity if needed. But make no mistake, this is not about manipulating inputs/assumptions to give you the answer you want, a common pitfall of QRAs. Your approach must always remain demonstrably conservative to support a robust safety assessment. Another common mistake is that of ‘salami slicing’. Whilst the QRA of an individual scenario/fault may show the risk to be acceptable, if a number of scenarios/faults impact on the same people, the overall cumulative risk may not be acceptable. Your QRAs must be adequately linked to assess overall risk. Finally, always remember a QRA is not a ‘one-stop-shop’. A screening exercise using deterministic means is required to


IS THERE A ROLE FOR QRA’S IN THE WIND ENERGY INDUSTRY? In the next issue we will explore some specific examples which show that there is a role for QRA in the Wind Energy Industry. However this is certainly not a black and white issue, the nature and scope of any QRA will vary hugely based on a range of factors including; nature of the hazard and its development, available information, existing precedents, stakeholder expectations, but perhaps more crucially, what role the QRA is to play within the overall safety justification strategy. This must be fully understood before embarking on any QRA.


Gareth Ellor


Risktec Solutions Ltd www.risktec.co.uk


DIFFERING ATTITUDES, DIFFERING SHADES OF WRONG! BLEAK


(1980, Major Oil Company Representative): “QRA is equivalent to counting the number of angels that can stand on the head of a pin. It can be concluded that risk analysis is likely to be a waste of time if applied to chemical processes”


BLAND


(1985, International Study Group on Risk Analysis): “The whole analytical exercise might be considered to be objective. However, it must be realised that because of the large body of assumptions, estimates, judgements and opinions involved, much of the input information is often subjective”


BULLISH


(1993, Extract from Major Oil Company Risk Engineering Standard): “QRA is a tool which helps translate hindsight (accidents) into foresight (planning) – showing ways and means (improved engineering, procedures and supervision) to prevent the calculated accidents from happening”


BLINKERED “Our QRA result is below the risk tolerability criteria so we are OK”


NOT BOTHERED “QRA gives us some numbers but does not significantly affect safety on the ground”


www.windenergynetwork.co.uk


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