Current Developments in a Low-Cost Continuous Holdup Monitor for Ductwork at Nuclear Facilities

A holdup monitoring system that can be permanently installed via a hub system or temporarily placed with long-lived battery-based units is under development at Oak Ridge National Laboratory. This system is composed of inexpensive, user-friendly, modular detectors that will undergo quality-assurance at the end of the project. This paper discusses recent developments in this holdup monitoring system, with an objective to reach a sub-$1,000 unit price using plastic scintillators and a silicon photomultiplier (SiPM)–based front end. Further improvements to the hub model include replacement of power and communications over USB with power and communications over ethernet. This allows for much longer cable runs between detectors and the home hub. Other work has included development of a cohesive, user-friendly interface with features such as automatic detection of plugged in detectors when generating a hub; easy access to detector settings, with an automated algorithm for locating some detector parameters such as an appropriate threshold setting; strip charts showing count rate history for each detector; and automated periodic data storage to external drives, in addition to the local drive on the hub.