BN & CFD-based quantitative risk assessment of the natural gas explosion in utility tunnels

The utility tunnel hosting the natural gas pipeline raises concerns about the potential gas explosion. Although some work focuses on risk assessment of leakage and explosion of the natural gas in utility tunnels, most of them are conducted by separate methods and do not integrate the process of leakage, dispersion, and explosion. In this work, a Bayesian network (BN) & computational fluid dynamics (CFD)-based quantitative risk assessment of the natural gas explosion in utility tunnels is proposed. By constructing BN to calculate gas leakage probability and applying CFD to simulate the gas dispersion and explosion consequences, the risk of natural gas explosion can be calculated. The possibilities of gas leakage, safety barrier failure, in-tunnel gas dispersion, and delay ignition time are all inputted to gas explosion consequences for both inside and outside areas. The results indicate that the outside risk of in-tunnel explosion cannot be neglected, although the inside risk is generally higher than the outside. And the emergency shutdown system (ESD) failure is the most fatal failure of all safety barriers that should be prevented with the most attention. The proposed model can be applied for the risk management of utility tunnels and other process facilities with hazardous materials inside.