含氚气体中氚分压BIX在线测量方法研究

摘要

建立了一种聚变堆氘氚燃料循环系统燃料气及工艺气等含氚混合气体中氚分压在线快速测量方法，该方法通过测量氚衰变产生的β射线与材料相互作用发射的轫致X射线（BIX ），利用轫致X射线的计数率与含氚气体氚分压的标定关系曲线，实现含氚气体中氚分压（活度浓度）的实时测量。该方法中的轫致X射线是通过β射线与表面喷金的铍窗材料作用而产生的，X射线的测量采用NaI（Tl）探测器。研究过程中建立了轫致X射线计数率与氚分压的标定关系曲线，对于纯氚气体，氚压测量范围为1 Pa～10 kPa（氚活度浓度为1012～1015 Bq／m3）时，计数率（C）与氚压（p）的标定曲线为 C＝5畅01×104（1－e－4畅55×10－5p ），其指数拟合相关系数为1畅00000。对于氚体积分数为1％的氚‐氦混合气体，氚分压测量范围为1～100 Pa（氚活度浓度为1011～1014 Bq／m3）时，计数率与氚分压的标定曲线为C＝5畅24×102（1－e－4畅69×10－3p ），其指数拟合相关系数为0畅99860。对于氚体积分数为1％的氚‐氢混合气体，氚分压测量范围为1～100 Pa（1011～1014 Bq／m3）时，计数率与氚分压的标定曲线为C＝5畅18×102（1－e－4畅61×10－3p ），其指数拟合相关系数为0畅99953。利用以上标定曲线，对任意氚分压的含氚混合气体进行验证测量，结果表明，该方法测量精度较高、响应速度快、测量稳定性好，在氚测量技术中是一种很有前景的方法。%A promising method of on‐line and real‐time measurement for gas containing tritium in fuel processing systems of DT fusion facility was introduced .The principle of this method is observing the bremsstrahlung X‐ray induced by the interaction betweenβparticles and material (BIX) .A correlation between the counting rate of bremsstrahlung X‐ray and the tritium partial pressure can be presented ,and it realizes the on‐line and real‐time monitoring of tritium partial pressure . The material used for generating bremsstrahlung X‐rays is a beryllium window with evaporated golden film on it .The bremsstrahlung X‐ray is monitored by a NaI (Tl) scintillation counter .For the pure tritium ,w hen the tritium partial pressure range is 1 Pa‐10 kPa (1012‐1015 Bq/m3 ) ,the calibration curve of C‐p is C= 5.01 × 104 (1 -e-4.55 × 10 -5p ) .For the 1% atoms tritium mixture diluted with helium/hydrogen ,when the tritium partial pressure range is 1 Pa‐100 Pa (1011‐1014 Bq/m3 ) ,calibration curves of C‐p are C=5.24 × 102 (1 -e-4.69 × 10 -3p ) and C=5.18×102(1-e-4.61×10 -3p)respectively .Thecorrelationcoefficientsof thethree kinds of gases are 1.000 00 ,0.998 60 and 0.999 53 respectively .Based on the above calibration curves ,the expressions in random tritium partial pressure were tested .The results show that this method is good at measuring accuracy ,responding rate and stabil‐ity .It is a promising method in tritium measuring technique .