TESTOPT

Testing of safety-critical equipment requires considerable resources and may also result in business interruption costs. Therefore, by testing less frequently, an operator can reduce costs, but may also incur greater risks as a result of the reduction in reliability of the equipment.

Using Cost Benefit Analysis, it is possible to identify a test interval for which it can be demonstrated, with a high degree of confidence, that the cost of increasing the test frequency is disproportionate to the risk reduction achieved. On this basis, it can be shown that, if tests are carried out at the proposed interval, risks remain As Low As Reasonably Practicable (ALARP).

We have developed this methodology into a user-friendly Decision Support Tool, TestOpt III, which analyses test data in order to provide justification for an increased test interval.

Techniques are included in the methodology to account for uncertainty in the relationship between failure rate, availability and risk level. A key component is the use of asset-specific test results to 'update' estimated failure rates.