Abstract
應用中子源於環境水體中進行污染物元素分析之研究始於民國75年, 由本實驗室首度提出並自行設計完成首部水污染物探測器一A 型探測器, 同時評估其可行性. 本研究乃根據瞬發加馬活化分析原理以行元素分析, 仍以鉲 (252Cf)中子源與高純鍺偵檢器之儀器組合, 改良原先設計並發展出新型之現場水中元素分析儀一B 型探測器及 C型探測器, 並進行其功能之測試與湖泊河流之現場測量.論文內容概分為三部份: (1) 改良A 型探測器而設計出可於現場操作之B 型探測器及偵測浮台, 於校園內湖泊中分析湖水污染物. (2) 發展新型之 C型探測器, 於一模擬現場之測試桶內評估其功能. (3) 架設 C型探測器於漁船上, 在淡水河域實施河水鹽度現場偵測.實驗結果顯示 C型探測器具有下述優點: (1) 系統整體重量輕, (2) 易於現場安裝,(3) 有效偵測水體大, (4) 元素最小可測濃度低, (5) 偵檢器中子損傷小, 及(6) 環境中殘存活性與工作人員輻射劑量低, 優於其他兩型探測器而更適於水中元素或鹽度之現場測量, 可應用於污染水域中或工廠廢液排放口監測污染元素及鹽度. B型探測器適於偵測水中低能量加馬射線可改裝為水中放射性核種分析儀, 應用於核能設施及放射性物質使用場所附近環境水質現場監測.///////In Situ Environmental Monitoring Using Neutron ProbeAbstractApplication of neutron source to water pollutant monitoring in environment was forst proposed in our iaboratoruy in 1986. A self-designed 252Cf-HPGe model-A, consisting of 252Cf neutron source and high-purity germanium detector was constructed and evaluation of its feasibility was performed. In this work, the performances of newly developed 252Cf-HPGe model-B and model-C were evaluated in a water tank and in situ surveys were carried ouron lake and river .Results indicate the model-C has following advantages: (1) Flexibility toassemble, (2) large detecting range, (3) low detection limit, (4) low neutron damage to HPGe, (5) low residual activities in water and radiation exposure to workers; therefore, it is more suitable for in situ measurement of elemental concentration in polluted water or salinity variation in riverwater. The model-B, with neutron source and neutron/gamma shield removed,can be used to monitor leakage radionuclided in water mass around nuclearfacilities or radiochemical labs.