The nuclear industry’s expansion to encompass carbon-free electricity generation from small modular reactors and nuclear fuel reprocessing necessitates enhanced detection and monitoring of pure beta-emitting radioactive elements such as ³H and ⁸⁵Kr; this endeavour is crucial for nuclear safety authorities tasked with environmental monitoring. However, the short range of electrons emitted by these gases makes detection challenging. Current methods, such as ionization chambers and liquid scintillation, do not offer at the same time good sensitivity, real-time analysis and ease of implementation. We demonstrate an approach using a gas–solid mixture to overcome these limitations. We synthetized a transparent and scintillating nanoporous material, an aerogel of Y₃Al₅O₁₂:Ce⁴⁺, and achieved real-time detection with an efficiency of 96% for ⁸⁵Kr and 18% for ³H. The method reaches a sensitivity below 100 mBq per cm³ over 100 s measurement time. We are able to measure simultaneously as mixtures containing both ³H and ⁸⁵Kr a capability not possible previously. Our results demonstrate a compact and robust detection system for inline measurement of strategic radioactive gases. This combination of concept and method enhances nuclear power plant management and contributes to environmental safeguarding. Beyond the detection issues, this concept opens a wide field of new methods for radionuclide metrology.

核工业的扩展包括小型模块化反应堆的无碳发电和核燃料后处理，因此需要加强对³ H 和⁸⁵ Kr 等纯 β 发射放射性元素的检测和监测；这项努力对于负责环境监测的核安全当局至关重要。然而，这些气体发射的电子射程短，使得检测具有挑战性。目前的方法，例如电离室和液体闪烁，不能同时提供良好的灵敏度、实时分析和易于实施。我们展示了一种使用气固混合物来克服这些限制的方法。我们合成了一种透明闪烁的纳米多孔材料——Y ₃ Al ₅ O ₁₂ :Ce ⁴⁺气凝胶，并实现了实时检测， ⁸⁵ Kr 的检测效率为 96%， ³ H 的检测效率为 18%。该方法达到了一定的灵敏度。在 100 秒的测量时间内低于 100 mBq/cm ³ 。我们能够同时测量包含³ H 和⁸⁵ Kr 的混合物，这是以前不可能实现的。我们的结果展示了一个紧凑而强大的检测系统，用于在线测量战略放射性气体。这种理念和方法的结合增强了核电厂的管理并为环境保护做出了贡献。除了检测问题之外，这一概念还为放射性核素计量新方法开辟了广阔的领域。