Multi-channel plastic-scintillator-based detection system for monitoring tritium in air

Abstract

To overcome the limitations of the ionization chamber-based tritium monitor, a design for a multichannel plastic scintillator-based detection chamber for monitoring tritium in air is proposed. The performance of the chamber was characterized by Monte Carlo-based calculations with various design parameters such as thickness of the plastic scintillator (t) and number of channels (n). We considered the volume and detection efficiency of the chamber to evaluate the performance of the detector. The expected counting rate curve was in good agreement with the expected simplified physical model. The minimum detectable activity (MDA) was shown at t = 0.5 mm and n = 48 and estimated to be 29.9 kBq/m3. Compared with the experimentally estimated MDA, the relative difference was approximately 24%. However, this difference is understandable considering the different lower level of discrimination and light loss during transportation assumed in the model. The proposed tritium detection chamber is expected to be useful for environmental monitoring at some level as well as for monitoring of tritium leaks from fusion or CANada Deuterium Uranium (CANDU)-type reactors.

Development of a Novel Passive Monitoring Technique to Showcase the 3D Distribution of Tritiated Water (HTO) Vapor in Indoor Air of a Nuclear Facility

“…Releases of radionuclides from nuclear facilities may cause negative health effects but are even more likely to trigger public concern and hence cause socioeconomic damage. , Comprehensive and reliable monitoring of anthropogenic radionuclides in the environment, therefore, is essential for nuclear safety and risk assessment of occupational exposure. − Among various anthropogenic radionuclides, tritium ( 3 H) is noteworthy due to its relatively long half-life ( T 1/2 = 12.33 years) and high migration capacity. − As a radioactive isotope of hydrogen, 3 H is omnipresent as tritiated water (HTO) vapor in air, leading to widespread distribution through the water cycle and food chain. − Despite analytical challenges due to tritium’s volatility and low-energy beta decay, radiation regulatory authorities have extensively documented airborne HTO dynamics in many countries over the past decades. − Concerning the indoor atmosphere of nuclear facilities, HTO monitoring primarily serves for surveillance monitoring to diagnose reactor status and assess occupational exposure. − Although online tritium monitoring instruments (e.g., ionization chambers) provide timely information in case of accidental leakage, the high instrument costs, high detection limits, and single-point radiation measurement limit their ability to characterize the spatiotemporal heterogeneity of HTO in large volumes of indoor air, such as reactor halls. , Without exact and quantitative knowledge on HTO in air, small leakages from nuclear installations cannot be pinpointed accurately, and the development of proper strategies for nuclear facility decommissioning may also influenced. Therefore, a supplementary method for the comprehensive characterization of HTO vapor in nuclear facilities is desired to meet future challenges resulting from nuclear power expansion based on both fission and fusion.…”

“…18−20 Although online tritium monitoring instruments (e.g., ionization chambers) provide timely information in case of accidental leakage, 21 the high instrument costs, high detection limits, and single-point radiation measurement limit their ability to characterize the spatiotemporal heterogeneity of HTO in large volumes of indoor air, such as reactor halls. 22,23 Without exact and quantitative knowledge on HTO in air, small leakages from nuclear installations cannot be pinpointed accurately, and the development of proper strategies for nuclear facility decommissioning may also influenced. Therefore, a supplementary method for the comprehensive characterization of HTO vapor in nuclear facilities is desired to meet future challenges resulting from nuclear power expansion based on both fission and fusion.…”

Laminated Flow-Cell Detector with Granulated Scintillator for the Detection of Tritiated Water

“…Another flow-cell detector by Jun Woo Bae and team [12] used sheets of a plastic scintillator layered upon each other to form a rectangular cavity. The detector was tested with two concentrations of tritiated hydrogen gas, finding a clear improvement in the 12channel chamber when compared to a single-channel chamber, with a detection efficiency of 1.78 ± 0.04% for the single channel and 27.91 ± 0.49% for the 12-channel chamber.…”