CCF Probability approach thesis application

Objective
An important first step to develop means to Quantify, Improve, Credit and Validate CCF (Common Cause Failure) defences is to find an approach that allows quantifying and crediting specific CCF defences in the PSA context.

The objective with this project is to make conclusions if an approach very similar to the SLIM MAUD Human Error Probability approach is feasible and a possible way forward to allows quantifying and crediting of specific CCF defences and if useful results can be obtained.

Program
The British UPM approach is driven by assessing a target system’s defences to derive CCF probabilities. A possible development of this approach is to link the UPM assessment (tables) to reality, via CCF event data. For a given component type the following validation is required:

* Weighting of importance of defence factors
* Parametric model parameter ranges; and
* Sensitivity of parameter to strength of defence.

An approach very similar to the SLIM MAUD Human Error Probability approach can be used for this type of calibration of specific CCF defence factors:

HEP = e^(a(SLI)+b)

where:

* HEP is the human error probability (or CCF probability)
* a and b are empirically derived constants;
* SLI is success likelihood index, given by: (se hemsida nedan för summaformel)
* PSF is the performance shaping factor; and
* w is the weighting of the specific PSF.

In terms of CCF and UPM, w can be considered similar to the defence weighting and PSF to the strength of a specific defence. This way the HEP approach can be transformed into a CCF probability approach.

The results of the Thesis Application shall make conclusions if this approach is feasible and a possible way forward and if useful results can be obtained. Possible improvements to the basic idea shall be investigated and alternative solutions shall be tested and demonstrated within a reasonable scope.