論文中利用GOTHIC程式建立核一廠一次圍阻體與IMI/Sulzer設計之圍阻體過濾排氣系統(Filtered Containment Venting System, FCVS)之GOTHIC分析模式。在保守假設下，利用此GOTHIC模型探討三個案例：第一個案例探討利用FCVS進行排氣時FCVS內空氣體積分率下降至20%以下無發生氫氣爆炸之風險所需時間；第二個案例探討當圍阻體內部高氫氣體積分率之氣體排入初始氣體狀態為100%空氣之FCVS內部時，開啟暫態之空氣與氫氣體積分率組合是否會進入可爆燃區或可爆轟區而有發生氫氣爆炸之風險；第三個案例探討若FCVS無法正常關閉，圍阻體於低壓力時仍利用FCVS排氣，是否會有空氣流入FCVS導致FCVS內空氣體積分率上升而有氫氣爆炸之風險。研究結果顯示，在大量產生氫氣前開啟FCVS，60秒內FCVS內空氣體積分率皆下降至20%以下；大量產生氫氣後開啟FCVS，40秒內FCVS內空氣體積分率皆下降至20%以下；FCVS內的氣體體積分率組合在FCVS開啟暫態時間可進入可爆燃區或可爆轟區；若FCVS無法正常關閉，圍阻體在低壓力下仍利用FCVS排氣，結果顯示無空氣流入FCVS使空氣體積分率上升。針對降低FCVS氫氣爆炸風險之方法，建議對FCVS加裝氮氣注入裝置，並在FCVS開啟前對FCVS填入氮氣降低空氣體積分率避免開啟暫態之氫氣爆炸風險；加裝預熱裝置，在開啟FCVS前對管路預熱，避免水蒸氣被管路中冷空氣及管壁冷凝使空氣與氫氣體積分率上升而增加氫氣爆炸風險；避免FCVS管壁有累積靜電產生火花之可能，例如使管壁良好接地。

In this study, we construct the GOTHIC model of Chin Shan Nuclear Power Plant and FCVS (Filtered Containment Venting System) designed by IMI/Sulzer with GOTHIC code. Under conservative assumptions, we investigate the three cases: the first case investigate how long does it take to lower volume fraction of air of FCVS to below 20%; the second case investigate whether the combination of the volume fraction of air and volume fraction of hydrogen can enter flammable or detonable region at the transient of opening; the third case investigate whether the air will flow into FCVS when venting under low pressure;. The consequence of this study shows that the volume fraction of air of FCVS will be lower than 20% in 60 seconds; the combination of volume fraction of air and volume fraction of hydrogen can enter flammable or detonable region at the transient of opening; air will not flow into the FCVS when venting with FCVS even under low pressure. To lower the risk of hydrogen explosion, we suggest that when using FCVS, it should equip with nitrogen vessel and preheater to make the FCVS inert and avoid steam condensation before venting with FCVS, and accumulation of static electric charge should be avoided during venting process at any place of the venting route.

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