Technical Report NTB 91-07

Determination of the Cl content in reactor cooling water and actives resins from Swiss nuclear power plants

36Cl concentration was determined in reactor cooling water and in Reactor Coolant Cleanup System (RCCS) resins from a Swiss pressurized water reactor (PWR). For detection of 36Cl, both accelerator mass spectroscopy (AMS) and liquid scintillation counting (LSC) techniques were used. In addition, the 36Cl content in resins from a second PWR and also from a boiling water reactor were determined. In all samples the concentration of the key nuclide 137Cs was also measured, which allowed the scaling factors for 36Cl relative to 137Cs to be determined. The resulting scaling factors for the resin samples are respectively [1.4, 2.2 and 17] × 10-6, in reasonable agreement with the single predicted value of 6.0 × 10-6 used so far by Nagra for estimating the 36Cl content of the resins from different reactors.

Measured and previously estimated 36Cl concentrations lie within a factor 2.4.

For the water sample from the PWR, the measured scaling factor was 5.8 × 10-5.