Development of an optical sensor for measuring opacity changes in polyvinyl toluene scintillators

Journal Article · Wed Oct 21 00:00:00 EDT 2020 · Radiation Physics and Chemistry (1993)

DOI:https://doi.org/10.1016/j.radphyschem.2020.109189· OSTI ID:1721608

Marianno, C. M. ^[1]; Ordonez, E. A. ^[1]; King, J. W. ^[1]; Suh, R. ^[1]

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1. Texas A & M Univ., College Station, TX (United States)

Polyvinyl toluene (PVT) based detectors are used in radiation portal monitors (RPMs) worldwide to detect the trafficking of illicit nuclear material. PVT scintillators, which are normally optically clear, have been observed to suffer internal fogging throughout their volume due to prolonged exposure to varying environmental conditions. These changes could lead to reduced performance for RPMs that utilize plastic scintillators. In this research, a proof of concept system, consisting of different color light emitting diodes (LEDs) and a single optical sensor (OS), were used to examine the change in light transmission through a PVT scintillator. This Optical Monitoring System (OMS), coupled with an environmentally exposed PVT detector, was tested in an environmental chamber where it was subjected to changes in temperature and humidity ranging from 55 °C at 100% relative humidity to –20 °C at 40% relative humidity. At temperatures below 10 °C, light transmission was reduced by 81% ± 8% for blue LEDs, 84% ± 5% for yellow LEDs, and 49% ± 4% for green LEDs. Similar reductions in detected light were not recorded when the OMS was tested with only air between the LEDs and OS. Therefore, the significant reductions in transmitted light were attributed to changes occurring within the PVT scintillator. These results indicate that a significant reduction in PVT opacity occurs due to wide environmental changes. A device such as the OMS could be used to track these changes and provide users an early indication that a portal monitor is suffering from reduced performance.

• Research Organization: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE; USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC04-94AL85000; NA0003525
• OSTI ID: 1721608
• Alternate ID(s): OSTI ID: 1810962
• Report Number(s): SAND--2019-13740J; 681341
• Journal Information: Radiation Physics and Chemistry (1993), Journal Name: Radiation Physics and Chemistry (1993) Vol. 179; ISSN 0969-806X
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

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