Kitzhaber Zechariah B, Orea Daniel, McFarlane Joanna, Manard Benjamin T, Andrews Hunter B
Radioisotope Science and Technology Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37830, United States.
Nuclear Energy and Fuel Cycle Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37830, United States.
ACS Omega. 2025 Aug 5;10(33):37889-37897. doi: 10.1021/acsomega.5c04988. eCollection 2025 Aug 26.
A method was developed to sample molten salts by sparging to generate and transport aerosols to an isolated instrument for compositional analysis by laser-induced breakdown spectroscopy (LIBS). Real-time monitoring of molten salt composition is critical to developing molten salt nuclear reactors, which offer enhanced safety and efficiency. In this article, the sparge sampling method is described and compared with sampling using a Collison nebulizer. The size distribution and transport of aerosols produced from molten eutectic NaNO-KNO salt were compared for multiple gas flow rates (75-1200 mL min) and transport distances (0.68-2.61 m). Both methods produced aerosols ranging from 0.5 to 5.0 μm determined using a cascade impactor. Aerosols were effectively transported without pre- or trace-heating of gas lines, but transport efficiency was reduced by the formation of agglomerates. Sparge sampling was found to use less sample and less gas than a Collison nebulizer while producing a more concentrated aerosol stream (up to 5 μg L). The effects of laser energy and delay time on the signal quality of LIBS measurements of these aerosols were also studied. High energy and short delay times were found to enhance signal and repeatability, whereas signal-to-background and signal-to-noise ratios were highest at low energy and longer delay times. The capabilities of this system for online monitoring of molten salts were demonstrated with calibrations for Sr and Li with relative standard deviations of 2.6% and 1.5% and limits of detection of 380 and 180 μg g, respectively.
开发了一种通过鼓泡对熔盐进行采样的方法，以产生气溶胶并将其传输到独立仪器，通过激光诱导击穿光谱法（LIBS）进行成分分析。熔盐成分的实时监测对于开发具有更高安全性和效率的熔盐核反应堆至关重要。在本文中，描述了鼓泡采样方法，并将其与使用碰撞雾化器采样进行了比较。比较了在多种气体流速（75 - 1200 mL/min）和传输距离（0.68 - 2.61 m）下，由共晶NaNO - KNO熔盐产生的气溶胶的尺寸分布和传输情况。使用串联冲击器测定，两种方法产生的气溶胶粒径范围均为0.5至5.0μm。气溶胶在不预热或微热气体管路的情况下能有效传输，但团聚物的形成会降低传输效率。发现鼓泡采样比碰撞雾化器使用的样品和气体更少，同时产生更浓缩的气溶胶流（高达5μg/L）。还研究了激光能量和延迟时间对这些气溶胶LIBS测量信号质量的影响。发现高能量和短延迟时间可增强信号和重复性，而在低能量和较长延迟时间下，信背比和信噪比最高。通过对Sr和Li进行校准，证明了该系统在线监测熔盐的能力，相对标准偏差分别为2.6%和1.5%，检测限分别为380和180μg/g。
