锦屏地下实验室防水抑氡工程技术与应用

Waterproof and radon suppression engineering technology and application at China Jinping underground laboratory

摘要

【目的】氡是一种惰性气体，由地下洞室岩体不断析出并衰变，严重干扰深地实验室中以暗物质研究为代表的前沿物理实验探测，危害实验人员健康。为降低实验空间氡含量，保持洞内环境干燥，【方法】中国锦屏地下实验室二期开创性地建造了一种特殊且轻薄的防水抑氡结构，将周围岩体渗出的氡和地下水均隔绝抑制在实验空间外，同时减少外用材料引入额外的辐射本底。率先开展了锦屏地下实验室不同防护结构和通风环境下空间空气氡浓度原位探测。【结果】结果显示：在通风良好的情况下，自研防水抑氡结构成功实现了平均空气氡浓度11.1 Bq/m³的极低氡含量的洁净空气环境；在没有新风系统的情况下，防水抑氡结构使室内氡含量降低至与原洞室条件相似洞室的18.75%;防水抑氡结构施工完成一年后，实验室内氡气浓度基本不变，同时保持了洞室内部全寿命周期无渗漏。【结论】结果表明：自研防水抑氡结构能够大幅降低室内氡气浓度，并保持室内氡气浓度不变且无渗漏，为全球地下实验室防水抑氡环境构建提供了新方法和新技术。

Abstract

[Objective] Radon, an inert gas continuously exuded and decayed from the surrounding rock of underground chambers, is seriously interfered with cutting-edge physical experiments, such as dark matter research in deep underground laboratories, and poses health hazards to experimental personnel. To reduce radon levels in the experimental space and maintain the dryness of the chamber environment, [Methods] a special lightweight waterproof radon-suppressing structure was innovatively constructed in Phase II of the China Jinping Underground Laboratory. This structure was designed to isolate radon and groundwater exuded from the surrounding rock outside the experimental space while minimizing additional radiation background introduced by external materials. Measurements of air radon concentration under different protective structures and ventilation conditions were conducted in situ.[Results] It was shown that, under good ventilation conditions, an ultralow radon concentration of 11.1 Bq/m³ was achieved with the self-developed waterproof radon-suppressing structure, creating a clean air environment. Without a fresh air system, radon concentrations were reduced to 18.75% of the level in a chamber with conditions similar to the original chamber. One year after the construction of the waterproof radon-suppressing structure, radon concentrations in the laboratory remained stable, and no leakage was observed throughout the lifecycle of the chamber.[Conclusion] The self-developed waterproof radon-suppressing structure was demonstrated to significantly reduce radon concentration in indoor environments, maintain stable radon levels without leakage, and provide a novel method and technology for constructing waterproof and radon-suppressing environments in underground laboratories worldwide.

关键词

防水抑氡 / 低辐射本底 / 中国锦屏地下实验室 / 室内氡测量 / 影响因素 / 地下水 / 地下洞室

Key words

waterproof and radon suppression / low radiation background / China Jinping underground laboratory / Indoor radon measurement / influencing factors / groundwater / underground cavity

基金资助

国家自然科学基金项目(U23B20146)