On the ill-conditioning of the multiphase flow measurement by prompt gamma-ray neutron activation analysis

Prompt gamma-ray neutron activation analysis (PGNAA) in conjunction with the so-called Monte Carlo library least-square (MCLLS) approach for the quantitative analysis is currently considered for rapid, non-intrusive and online measurements of multiphase oil/gas/seawater flow. The results of this work indicate that the current method would be feasible for measurements of multiphase flow provided that the ill-conditioning in the MCLLS approach could be treated appropriately. ► PGNAA technique is considered for multiphase flow measurement. ► MCLLS approach is considered for the quantitative analysis. ► Ill-conditioning in the MCLLS approach causes significant uncertainties. ► Alternative (a): combining PGNAA with γ-ray densitometry. ► Alternative (b): minimizing the condition number of the linear system.