氡子体未结合态份额的变化规律研究

氡及其子体对公众的辐射照射占天然辐射照射的一半以上，而室内氡子体未结合态份额是影响氡子体剂量转换系数的重要参数。为探究氡子体未结合态份额的变化及受室内外环境因素的影响规律，本研究采用自行开发的累积式氡子体未结合态份额采样装置，在北京大学技物楼室内外环境中开展了氡子体未结合态份额的年变化测量，并利用商用连续式氡子体测量仪测量了室内氡子体未结合态份额的日变化。实测结果表明：在室内和室外不同环境中，氡子体未结合态份额的年平均值分别为8.8%(6.4%～12.5%）和9.7%(4.9%～12.8%)；室内环境中氡子体未结合态份额相对稳定；室外环境中氡子体未结合态份额受环境因素影响大，波动较大；关于日变化，虽然室内平衡当量氡子体浓度呈现出明显的上午高下午低的日变化规律，但没有观察到未结合态份额有规律性的日变化。

Study on Variation of Unattached Fraction of Radon Progeny

Radon and its progeny contribute half of all radiation exposure of the public received from natural radiation ,w hile the unattached fraction of radon progeny plays an important role on its dose conversion factor .To understand better on the variation of the unattached fraction of radon progeny and how environmental factors work on it , both 24 h integrated monitor and real‐time continuous monitor were adopted by this study for the observation on annual variation and diurnal variation as well .The results of monthly field measurement show that the annual average of the unattached fraction of radon progeny is 8.8% (6.4%‐12.5% ) and 9.7% (4.9%‐12.8% ) for indoor and out‐door ,respectively .In indoor environments ,the unattached fraction of radon progeny is more stable compared with that of outdoors since indoor environmental factors are more stable .For diurnal variation ,even though radon equilibrium equivalent concentration has a disciplinarian variation ,higher in the morning and lower in the afternoon ,the var‐iation of the unattached fraction of radon progeny does not show any regularity .