CFBR-Ⅱ堆脉冲中子注量测量

Measurement of Pulse Neutron Flux in CFBR-Ⅱ

为了监测CFBR-Ⅱ堆辐照空间内脉冲中子注量,根据能谱随空间缓慢变化的特点,选择28个特征点,使用239Pu电离室对S活化片进行相对刻度,修正了不同空间区域能谱对S活化片测量的影响,测得了特征点的脉冲中子注量。该方法引入的不确定度为5%;脉冲产额为1.10×1016裂变时,距辐照腔底50mm处脉冲中子注量为5.87×1013cm-2;合成标准不确定度为11%。

To measure the pulse neutron flux in CFBR- Ⅱ, neutron spectrum have to be considered and corrected in different region. Using 239Pu ionization chamber and Sulphur activation foil, 28 places are calibrated. 5% fractional uncertainty is introduced in the flux measurement. As yield is 1.10×1016 fissions, pulse neutron flux is 5.87×1013 cm-2 at the point which is 50mm distance from the bottom of radiation chamber, the combined standard uncertainty is 11%.