[en] As part of calibration on a regulary basis, the Norwegian secondary standards on ionizing radiation were calibrated at the Bureau International des Poids et Mesures (BIPM) in Paris in 1991. The secondary standards set up the basis for the calibration service at the Norwegian Radiation Protection Authority. The X-ray range from 10 to 50 kV and 100 to 250 kV is covered, as well as γ-radiation from ⁶⁰Co (1.25 MeV). A new ionization chamber was calibrated in the ⁶⁰Co radiation beam in addition to calibration of existing secondary standards. Furthermore, two of the ionization chambers were also calibrated in water in the ⁶⁰Co radiation beam. This makes it possible to offer the radiotherapy centers in Norway a calibration factor based on calibration in water. 8 refs., 7 figs., 7 tabs