- 學位論文
龍門核能電廠外釋劑量冷卻水流失事故分析
A Study on the Explant Radiation Doses of Loss of Coolant Accident for Lung-Men Nuclear Plant
摘要
早期核能發展，因電力需求與能源危機影響，核能發電備受推崇並大量興建。然而1979年美國三哩島事故(Three Mile Island)，1986年蘇聯車諾比爾電廠事故(Chernobyl)，以及 2011年日本福島事故(Fukushima)，對核能工業造成打擊，民眾對核電也逐漸失去信心；而核能業界與研究機構分別對核能相關議題進行深入的研究與實驗，開發了許多核能分析軟體並進行進深的分析，其能提升核能運轉之安全。 本論文使用美國能源部所屬聖地亞(Sandia)國家實驗室研發之MELCOR 1.8.5 (Methods for Estimation of Leakages and Consequences of Releases)程式、MACCS 2 (MELCOR Accident Consequence. Code System) 程式及美國Fauske & Associates, Inc. (FAI)公司所研發之MAAP 5 (Modular Accident Analysis Program)程式進行龍門電廠事故之模擬。 分析之個案為冷卻水流失事故加入緊急操作程序，對消防水作設定，探討事故各階段之發展趨勢與外釋劑量間的關係，並比較兩程式的差異。本論文模擬結果中，MELCOR計算上較為詳細且嚴謹，如反應爐底部先是穿越管失效，後才因熱潛變失效，且在重置與下移現象發生後及反應爐失效後，部分熔渣仍殘留於反應爐內，也較為符合物理現象。 兩程式在消防水注入時間與發生之現象上，(1)MAAP於94秒前，MELCOR於100秒前注入，能維持爐心完整性(2) MAAP於4.25分鐘前，MELCOR於14.25分鐘前注入，可防止爐心熔融(3) MAAP於6.25小時前，MELCOR於5.56小時前注入，則能避免反應爐因熱潛變而失效。
並列摘要
In the 1970s, because of the increased demand for the electricity, the nuclear plants were popular and were built extensively. But after the Three Mile Island Accident in the United States in 1979, the Chernobyl Accident in Ukraine in 1986, and Fukushima Accident in Japan in 2011, nuclear power industries have been hard hit by these accidents, and people were beginning to lose faith for the safety of the nuclear power plants. Over the years since the TMI accident, to improve the safety of nuclear plants, the nuclear industry and the research institutions have carried out researches in the safety issues associated with the nuclear plants and have developed a number of nuclear safety analytical codes. This study used the MAAP 5 (Modular Accident Analysis Program) code, developed by Fauske & Associates, Inc. (FAI), MACCS 2 (MELCOR Accident Consequence. Code System) code and MELCOR 1.8.5 (Methods for Estimation of Leakages and Consequences of Releases) code, developed by Sandia National Laboratories, to analyze postulated accidents at the Lung-Men Nuclear Power Plant. The cases being analyzed were loss of coolant accident (LOCA) with Emergency Operation Procedures (EOPs) and controlled AC-Independent Water Addition (ACIWA) to explore each stage of phenomena and find the impact on the dose being released. From the analysis of the results obtained from the case studies, it was found that modeling of the behavior of the core when the core becomes molten in MELOCR was more rigorous. The bottom of the reactor vessel was calculated to be failed by penetration through the in-core monitoring instrument tube or control rod drive guide tubes at first, followed by the failure by creep rupture. In addition, after relocation of the core materials to migrate to the lower part of the reactor vessel and after the reactor failure, part of the core materials were modeled by the MELCOR to be still remained in the core region, which is consistent with the physical phenomena. Delayed injection of the fire water (at the volumetric flow rate of 950 gpm), (1) the core remained intact if time of delay for 94 sec and 100 sec, obtained from MAAP and MELCOR evaluations, respectively, (2) the core melted for delays of 14.25 min and 4.78 min, and (3) the reactor failed by creep rupture through for delays of 6.25 hr and 5.56 hr.