Research on the optimization of channels for monitoring activity of liquids in nuclear island and conventional island liquid waste discharge system of nuclear power plant

In Daya Bay and LingAo Plant Radiation Monitoring system retrofit project, channels for monitoring activity of liquids in Nuclear Island and Conventional Island Liquid Waste Discharge system will use on line liquid monitor to replace the existing off-line sampling monitor. A mathematical model was created by using of the Monte Carlo simulation software-MCNP5. After inputting several parameters about the on line liquid monitor measurement loop, the measurement range and the minimum detectable activity (MDA) of the on line liquid monitor calculated by MCNP5 are better than the existing off-line sampling monitor. The results indicates that it is feasible to use on line liquid monitor to monitor activity of liquids in Nuclear Island and Conventional Island Liquid Waste Discharge system, and the performance can completely meet the requirement of the original design of these channels, so as to realize the optimization of the radiation monitoring system. (authors)