Evaluating Factors Affecting the Permeability of Emulsions Used To Stabilize Radioactive Contamination from a Radiological Dispersal Device

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• 作者：Garey A. Fox and Victor F. Medina
• 刊名：Environmental Science & Technology
• 出版年：2005
• 出版时间：May 15, 2005
• 年：2005
• 卷：39
• 期：10
• 页码：3762 - 3769
• 全文大小：695K
• 年卷期：v.39,no.10(May 15, 2005)
• ISSN：1520-5851

文摘

Present strategies for alleviating radioactive contaminationfrom a radiological dispersal device (RDD) or dirty bombinvolve either demolishing and removing radioactivesurfaces or abandoning portions of the area near therelease point. In both cases, it is imperative to eliminateor reduce migration of the radioisotopes until the cleanupis complete or until the radiation has decayed back toacceptable levels. This research investigated an alternativestrategy of using emulsions to stabilize radioactiveparticulate contamination. Emergency response personnelwould coat surfaces with emulsions consisting of asphaltor tall oil pitch to prevent migration of contamination. The sitecan then be evaluated and cleaned up as needed. Inorder for this approach to be effective, the treatmentmust eliminate migration of the radioactive agents inthe terror device. Water application is an environmentalcondition that could promote migration into the externalenvironment. This research investigated the potentialfor water, and correspondingly contaminant, migrationthrough two emulsions consisting of Topein, a resinousbyproduct during paper manufacture. Topein C is anasphaltic-based emulsion and Topein S is a tall oil pitch,nonionic emulsion. Experiments included water adsorption/mobilization studies, filtration tests, and image analysisof photomicrographs from an environmental scanning electronmicroscope (ESEM) and a stereomicroscope. Bothemulsions were effective at reducing water migration.Conductivity estimates were on the order of 10^-8 cm s^-1for Topein C and 10^-7 cm s^-1 for Topein S. Water mobilitydepended on emulsion flocculation and coalescencetime. Photomicrographs indicate that Topein S consistedof greater and more interconnected porosity. Dilute foamsof isolated spherical gas cells formed when emulsionswere applied to basic surfaces. Gas cells rose to the surfaceand ruptured, leaving void spaces that penetratedthroughout the emulsion. These experiments indicate thatemulsions may be a viable means for containing RDDresiduals; however, improvements are needed for optimalperformance.