Abstract
We have developed a science-based predictive model for fogging of the scintillator plastics deployed in radiation portal monitors. The only input required is the weather conditions [i.e., daily high and low, for temperature and relative humidity (R.H.)]. The code utilizes this information, together with a thermodynamic model of the water content in equilibrium with the plastic surface, a diffusion model of the water transport into the interior of scintillator plastic panel, and a comparison of the resulting paired “water-content/night-temperature” points as a function of position in the panel against an empirical “fog-line” that establishes a water/temperature criterion for the onset of fogging. We have analyzed the behavior of several representative portal monitor sites, and the output of the model analysis is reasonably consistent with observation.
| Original language | English |
|---|---|
| Article number | 161784 |
| Journal | Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment |
| Volume | 954 |
| DOIs | |
| State | Published - Feb 21 2020 |
Funding
This work was performed under the auspices of the U.S. DOE by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and was supported by the U.S. Department of Homeland Security, Domestic Nuclear Detection Office , under competitively awarded contracts IAA HSHQDN-17-X-00035 and HSHQDN-17-X-00051 . This support does not constitute an expressed or implied endorsement on the part of the Government. The authors wish to offer their gratitude to many additional individuals at Lawrence Livermore National Laboratory, Sandia National Laboratory, Pacific Northwest National Laboratory, and Oak Ridge National Laboratory, who participated in experiments and activities that provided insights into the nature of fogging for scintillator plastics in RPMs. Special thanks is offered to Erik Swanberg (LLNL) for his work in writing a C＋＋ code and sharing important insights. Approval number is: LLNL-JRNL-755692. This work was performed under the auspices of the U.S. DOE by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and was supported by the U.S. Department of Homeland Security, Domestic Nuclear Detection Office, under competitively awarded contracts IAA HSHQDN-17-X-00035 and HSHQDN-17-X-00051. This support does not constitute an expressed or implied endorsement on the part of the Government. The authors wish to offer their gratitude to many additional individuals at Lawrence Livermore National Laboratory, Sandia National Laboratory, Pacific Northwest National Laboratory, and Oak Ridge National Laboratory, who participated in experiments and activities that provided insights into the nature of fogging for scintillator plastics in RPMs. Special thanks is offered to Erik Swanberg (LLNL) for his work in writing a C＋＋ code and sharing important insights. Approval number is: LLNL-JRNL-755692.
| Funders | Funder number |
|---|---|
| U.S. Department of Energy | |
| U.S. Department of Homeland Security | |
| Lawrence Livermore National Laboratory | DE-AC52-07NA27344 |
| Oak Ridge National Laboratory | LLNL-JRNL-755692 |
| Sandia National Laboratories | |
| Pacific Northwest National Laboratory | |
| Domestic Nuclear Detection Office | IAA HSHQDN-17-X-00035, HSHQDN-17-X-00051 |
Keywords
- Scintillator plastic fogging