Preventing Tritium Memory Effects in Ion Chambers Using Ultraviolet LEDs

Abstract

Ion chambers are often employed to measure the concentration of tritium within flowing gases. In real world environments the active surfaces of ion chambers become covered with tritiated surface contaminants. This tritiated surface contamination often creates a large background response that can mask the signature of interest, which is the tritium concentration in the gas phase. Previous efforts to reduce the effects of surface contamination in ion chambers utilize inert coatings (e.g., gold) and low surface area electrodes (e.g., wire mesh). These strategies only reduce the effect and do not provide information regarding the ratio of the current from the contaminated surface to the current from the volume of the detector. Additionally, gold coating is expensive, substantially increasing the cost of the instrument. While ion chambers may be periodically cleaned, this recurring hands-on task does not adequately address tritium level ambiguities in gloveboxes and increases the risk of detector damage and worker exposure. An ideal solution to this issue would be to either develop an ion chamber that does not accrue surface contamination, or one that is self-cleaning while it is in operation. In this report we describe the development of using ultraviolet (UV) LED light illumination to desorb contamination from ion chambers while they are in operation, preventing the negative effects of surface contamination.