Gas system failure rate

Gasunie buys and sells gas. This paper is about calculating the failure rate of the gas transport system of Gasunie in the Netherlands. The pipes in the network are connected at certain stations which may operate at degraded levels due to technical problems. The transport system, modelled as an optimization problem, needs to be checked for feasibility for every configuration of the degradation levels at all stations in order to see whether the system fails or not. The discrete probability distributions of the degradation levels at every station in the network are given. The number of possible combinations of degradation levels is huge and the computations for the feasibility of the gas network are computer-intensive. This paper presents a new algorithm for approximating this rate and it is parsimonious in actually checking for feasibility.