A radiation transport model as a design tool for gamma densitometers

A flexible EGS4 Monte Carlo model was developed to simulate radiation transport in low-energy gamma-ray densitometers which are used for void (gas) fraction measurements in gas/liquid pipe flows. The detector responses produced by the model with 241Am gamma-ray input proved to be accurate in benchmarking experiments using real data. The verification was performed with homogeneous mixed flows at different void fractions. The model is being used to optimize measurement geometry in multibeam densitometers where the ultimate aim is to reduce measurement errors caused by flow-regime (gas/liquid distribution) variations in the pipe cross-section. The flexibility of the model allows parameters such as photon energy, pipe material and dimensions, and beam width to be changed easily. (author)