運用ALOHA，FTA，SAFETI評估液氯運作場所之危害特性

Assessment Hazard of Liquid Chlorine from Waterworks by FTA, ALOHA and SAFETI

廖茂洲(Mau-Jou Liau) ； 陳俊瑋(Jiun-Wei Chen) ； 雲瑞龍(Ray-Lung Yun) ； 魏建銘(Jian-Ming Wei) ； 張榮興(Rung-Shing Jang) ； 徐啓銘(Chi-Min Shu)

《勞工安全衛生研究季刊》 19卷3期 (2011/09) Pp. 457-467

https://doi.org/10.7005/JOSH.201109.0457

摘要

日常生活中，人們經常用到的消毒劑千百種，例如：漂白水、臭氧、碘酒等等。縱使消毒劑廣泛地使用帶給人們生活上極大的便利，但其潛在的危害亦是不容忽視的。本研究針對自來水淨水消毒過程中經常用到的化學物質液氯，依某淨水廠內相關液氯設備進行危害後果及風險評估。倘若液氯鋼瓶、液氯管線、加氯機等設備發生洩漏事故，除可能造成人命的傷亡外，亦會造成環境的污染。因此吾人選用FTA(Fault Tree Analysis)進行定性與定量危害分析，再輔以SAFETI(Suite for the Assessment of Flammable, Explosive and Toxic Impacts)，ALOHA(Areal L℃ation of Hazardous Atmospheres)兩種風險評估軟體，針對上述這些設備進行後果分析及風險評估，希望藉此界定洩漏之影響範圍，作為緊急應變規劃之參考。從結果可以得知在相同大氣條件下(23.8℃, 6m/s, F)ALOHA於ERPG-3(20ppm)後果影響距離為3.2km較SAFETI 1.125km遠。在不同地大氣穩定度下(23.8℃, F)(23.8℃, D)吾人可以看到ALOHA於ERPG-3(20ppm)後果影響距離分為3.2km和1.8km而SAFETI則分別為1.375km和1.125km。在社會及個人風險方面，各洩漏個體的風險等高線皆屬於可接受風險，因此發生洩漏危害事件相對而言，並不會對廠區外造成顯著之影響；而1×10^(-7)/年至1×10^(-9)/年等高線超過廠區範圍，但是並未與週界民眾接觸，洩漏評估結果皆為可接受範圍。而在社會風險方面，廠區的頻率與致死機率(FN-Curve)與風險等皆為可接受的風險。

關鍵字

失誤樹 ； SAFETI ； ALOHA ； 個人風險 ； 社會風險

並列摘要

In Taiwan, liquid chlorine from waterworks mostly is stored in the steel cylinder. In this study, weapplied Areal L℃ations of Hazardous Atmosphere, Suite for the Assessment of Flammable, ExplosiveandToxic Impacts and fault tree analysis (FTA) to analyze the aftermath for chlorine leakage. FTA was used as a tool to simulate potential or credible events during upsets. In general, an event was estimated from its starting point, and then we inferred the reasons of an event by its clue. Moreover, we calculated the probability of an event from method above clue. ALOHA is often adopted to calculate the risk of an emergency accident. We estimated the diffusion concentration of pollutants from the parameters including l℃al terrain, meteorological conditions, and leakage patterns. By comparing stability class F with stability class D, we obtained chlorine consequence distance in the stability class F is greater than stability class D. As an important factor, the stability class did affect the consequence distance. By comparing chlorine in two temperatures (23.8℃, 36.1℃), consequence distance will increase along with the temperature increases. Assuming ALOHA and SAFETI are run in the same conditions, such as wind speed, stability class, and humidity, the affected range of ALOHA is greater than SAFETI.

並列關鍵字

ALOHA ； Fault tree analysis ； Risk/Liquid chlorine ； Waterworks

參考文獻

NOAA,U.S. EPA(1999).ALOHA 5.2.3 Online Help.USA:Office of Response and Restoration of the National ℃eanic and Atmospheric Administration.

CAMEO(2006).ALOHA User Manual.

USEPA,NOAA(2007).Area L℃ations of Hazardous Atmosphere (ALOHA) Users Manual.

美國化學安全與危害調查局，http://www.chemsafety.com/cir.

環境與安全衛生技術發展中心，http://www.cesh.itri.org.tw/index.php.