Improvement of measurement technique of niobium reaction rate for fast reactor dosimetry

Ito, Chikara   ; Maeda, Shigetaka   ; Sekine, Takashi ; Aoyama, Takafumi 

The high accurate and precise measurement of Nb(n,n')Nb reaction rate was established for fast reactor dosimetry. The effect of self-absorption on measuring X-rays emitted by Nb was decreased by the solution and evaporation to dryness of niobium dosimeter. The high precision number of Nb atoms was obtained by measuring niobium solution concentration using the inductively coupled plasma mass spectrometry. X-rays of Nb were measured accurately by means of comparing an X-rays intensity of irradiated niobium solution with the intensity of the solution to which stable Nb was added. The measurement error of Nb(n,n')Nb reaction rate was improved to be less than 3 %, which was equivalent to the other reaction rate error of dosimeters for the Joyo dosimetry.