Abstract: The technology of in-situ gamma-spectrometry source term measurement for primary system of NPPs was introduced in the paper. The measurement system was developed based on HPGe detector. Numerical efficiency calibration technique was developed based on the Mnote Carlo method. The comparisons between numerical calibration and point source experiments showed that relative deviations were within ±5% and ±10% in the energy of 300—1 408 keV for the HPGe detector without and with collimator, respectively. The measurement system had been applied for the activated corrosion source term measurement campaigns during the outage of PWR-NPPs in China. The on-site measurement results showed that it could perform a good measurement accuracy for typical radionuclides, such as ⁶⁰Co, ⁵⁸Co, ^110mAg, etc., which were the major contributors to radiation field. The relative deviations of the contacted dose rate between calculation and measurement value were mostly within ±40%.

Key words: radiological characterization, activated corrosion product, in-situ gamma spectrometry, HPGe detector