PDF(Pubmed)
Abstract：
Aim of a low radon cleanroom technology is to minimize at the same time radon, radon decay products concentration and aerosol concentration and to minimize deposition of radon decay products on the surfaces. The technology placed in a deep underground laboratory such as LSM Modane with suppressed muon flux and shielded against external gamma radiation and neutrons provides \"Zero dose\" space for basic research in radiobiology (validity of the LNT hypothesis for very low doses) and for the fabrication of nanoelectronic circuits to avoid undesirable \"single event effects.\" Two prototypes of a low radon cleanroom were built with the aim to achieve radon concentration lower than 100 mBq·m3 in an interior space where only radon-free air is delivered into the cleanroom technology from a radon trapping facility. The first prototype, built in the laboratory of SÚRO Prague, is equipped with a standard filter-ventilation system on the top of the cleanroom with improved leakproofness. In an experiment, radon concentration of some 50 mBq·m-3 was achieved with the filter-ventilation system switched out. However, it was not possible to seal the system of pipes and fans against negative-pressure air leakage into the cleanroom during a high volume ventilation with the rate of 3,500 m3·h-1. From that reason more sophisticated second prototype of the cleanroom designed in the LSM Modane uses the filter-ventilation system which is completely covered in a further improved leakproof sealed metal box placed on the top of the cleanroom. Preliminary experiments carried out in the SÚRO cleanroom with a high radon activity injection and intensive filter-ventilation (corresponding to room filtration rate every 13 s) showed extremely low radon decay products equilibrium factor of 0.002, the majority of activity being in the form of an \"unattached fraction\" (nanoparticles) of 218Po and a surface deposition rate of some 0.05 mBq·m-2·s-1 per Bq·m-3. Radon exhalation from persons may affect the radon concentration in a low radon interior space. Balance and time course of the radon exhalation from the human body is therefore discussed for persons that are about to enter the cleanroom.
摘要：
低氡洁净室技术的目的是同时尽量减少氡，氡衰变产物浓度和气溶胶浓度，并尽量减少氡衰变产物在表面上的沉积。该技术放置在诸如LSMModane之类的深层地下实验室中，具有抑制的μ子通量，并可以抵抗外部伽马辐射和中子，这为放射生物学的基础研究提供了“零剂量”空间（LNT假设对极低剂量的有效性）和纳米电子电路的制造，以避免不良的“单事件效应”。“建造了两个低氡洁净室的原型，目的是在只有无氡空气从氡捕获设施输送到洁净室技术的内部空间中，使氡浓度低于100mBq·m3。第一个原型，建在布拉格苏罗的实验室，在洁净室的顶部配备了标准的过滤通风系统，提高了防漏性。在一个实验中,关闭过滤通风系统后，氡浓度达到约50mBq·m-3。然而,在3,500m3·h-1的大容量通风过程中，无法密封管道和风扇系统，防止负压空气泄漏到洁净室。因此，LSMModane设计的洁净室更复杂的第二个原型使用过滤通风系统，该系统完全覆盖在洁净室顶部的进一步改进的防漏密封金属盒中。在SRO洁净室中进行的初步实验具有高的ra活性注入和密集的过滤通风（相当于每13s的房间过滤速率），显示出极低的ra衰变产物平衡因子为0.002，大部分活性为218Po的“未附着分数”（纳米颗粒），每Bq·m-3的表面沉积速率约为0.05mBq·m-2·s-1。人的氡析出可能会影响低氡内部空间的氡浓度。因此，对于即将进入洁净室的人，讨论了人体中氡呼气的平衡和时间过程。
