Performance of a low activity beta-sensitive 90Sr water monitor

A continuous on-line beta sensitive water monitor was developed to determine the 90Sr activity levels in water after processing at the Fukushima nuclear power plants. The sensitivity required by the customer, 10 Bq kg−1, posed issues for any existing continuous on-line technology. The developed water monitor has maximized the efficiency to beta radiation while minimizing gamma background, and achieves a minimum detectable concentration of 6.3 Bq kg−1 in a 1 h measurement.