Garrett Londrea J, Morgan Bryan W, Burger Miloš, Lee Yunu, Kim Hyeongbin, Sabharwall Piyush, Choi Sungyeol, Jovanovic Igor
Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109, USA.
Gérard Mourou Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI 48109, USA.
Sensors (Basel). 2023 Jan 7;23(2):691. doi: 10.3390/s23020691.
Increased absorption of optical materials arising from exposure to ionizing radiation must be accounted for to accurately analyze laser-induced breakdown spectroscopy (LIBS) data retrieved from high-radiation environments. We evaluate this effect on two examples that mimic the diagnostics placed within novel nuclear reactor designs. The analysis is performed on LIBS data measured with 1% Xe gas in an ambient He environment and 1% Eu in a molten LiCl-KCl matrix, along with the measured optical absorption from the gamma- and neutron-irradiated low-OH fused silica and sapphire glasses. Significant changes in the number of laser shots required to reach a 3σ detection level are observed for the Eu data, increasing by two orders of magnitude after exposure to a 1.7 × 10 n/cm neutron fluence. For all cases examined, the spectral dependence of absorption results in the introduction of systematic errors. Moreover, if lines from different spectral regions are used to create Boltzmann plots, this attenuation leads to statistically significant changes in the temperatures calculated from the Xe II lines and Eu II lines, lowering them from 8000 ± 610 K to 6900 ± 810 K and from 15,800 ± 400 K to 7200 ± 800 K, respectively, for exposure to the 1.7 × 10 n/cm fluence. The temperature range required for a 95% confidence interval for the calculated temperature is also broadened. In the case of measuring the Xe spectrum, these effects may be mitigated using only the longer-wavelength spectral region, where radiation attenuation is relatively small, or through analysis using the iterative Saha-Boltzmann method.
为了准确分析从高辐射环境中获取的激光诱导击穿光谱（LIBS）数据，必须考虑因暴露于电离辐射而导致的光学材料吸收增加的情况。我们通过两个模拟新型核反应堆设计中诊断情况的例子来评估这种影响。分析是基于在环境氦气环境中含有1%氙气以及在熔融氯化锂 - 氯化钾基质中含有1%铕的LIBS数据进行的，同时还包括对伽马射线和中子辐照的低羟基熔融石英和蓝宝石玻璃的测量光学吸收。对于铕的数据，观察到达到3σ检测水平所需的激光脉冲数有显著变化，在暴露于1.7×10 n/cm的中子注量后增加了两个数量级。对于所有检查的情况，吸收的光谱依赖性会导致系统误差的引入。此外，如果使用来自不同光谱区域的谱线来创建玻尔兹曼图，这种衰减会导致从氙II线和铕II线计算出的温度发生统计学上显著的变化，对于暴露于1.7×10 n/cm注量的情况，分别从8000±610 K降至6900±810 K以及从15800±400 K降至7200±800 K。计算温度的95%置信区间所需的温度范围也会变宽。在测量氙光谱的情况下，可以仅使用辐射衰减相对较小的较长波长光谱区域，或者通过使用迭代萨哈 - 玻尔兹曼方法进行分析来减轻这些影响。
