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Continuous Radon and Radon Progeny Monitors.

Designed to work in the harsh environments present in uranium mines and mills, alphaNUCLEAR PRISMs have been a staple for radon and radon progeny monitoring for decades.

PRISMs are area monitors used for providing workers in industrial environments with an indication of current radon and radon progeny levels. In addition to providing a readout of current level values on a LCD screen, PRISMs feature three ultra-bright LED lamps, allowing workers to know at a glance if it is safe to be in an area. The light’s activation levels are user configurable, and provide up to five levels that can be triggered off of radon and/or radon progeny levels.

There are currently two models of PRISMs.


The M597 PRISM is alphaNUCLEAR’s popular and robust continuous radon and radon progeny level monitor that has been in use for over a decade. Its proven and robust framework ensures consistent and accurate results. Samples are continuously collected and are integrated over 10 minutes, providing a high level of accuracy.


The M601 PRISM is is the next generation of alphaNUCLEAR’s popular Model 597 Continuous Radon & Working Level Monitor.

Built on the stable and reliable framework of the previous models and proven detector technology, the M601 takes advantage of advancements in system-on-chip (SOC) technology to provide faster response times for changing radon and radon progeny conditions. The M601 also adds advanced networking capabilities allowing the M601 to communicate with a distributed control system (DCS) through the Modbus protocol over ethernet or Wi-Fi.

Results from the M601 are updated every minute and are integrated over the previous 1 to 10 minutes to provide an appropriate level of precision. These results are stored on 30 GB of internal data storage, which is enough storage to record data for the lifetime of the device.

Each PRISM has internal data storage. Each time a unit is turned off and on, or a job run is programmed via a configuration utility, a new result file is created. When the unit is plugged in to the USB port of a computer, the data storage device will show up as a Removable Storage Device. The result files can then be copied to the computer or other storage device.

A membrane switch located on the side of the unit performs multiple tasks. Pressing the switch for less than a second will turn the LCD backlight on for easy visibility of the data, and then after a few seconds the screen displays the filter and battery status along with time and date. If the switch is held for more than a second, all the indicator lights will turn on, the screen informs you it is testing the lights, and it also shows the firmware version installed in the unit.

All PRISMs are fitted with an internal rechargeable battery. This battery can support over 12 hours of operation without power from the AC adapter/battery charger.

A stainless-steel cover is provided to protect the instrument in extremely hostile environments (underground mining). An optional stainless-steel slide-in mounting bracket is available to retain the PRISM on a shelf structure.

A waterproof LEMO connector provides control signals for optional external light box systems. These light box systems can include a horn and relay contacts for external connection.

PRISM Features

  • User Interface: USB.
  • Internal Data Storage: 2 GB (M597), 30 GB (M601) Internal Memory.
  • Security / Anti-Tamper: On/off key, proprietary cabling, configuration utility required to change operational parameters and calibration data.
  • Age of Air Compensation: Dynamic progeny ratio based on measured results.
  • Warning Light System: Thresholds based on radon gas and working level concentrations.
  • Setup: No setup required. Default run is continuous, however there is the ability to create programmed runs of specific length.
  • Data Analysis: Results are calculated internally during each sample period, with no decay period required. No post-processing of data is required. Data is saved in internal memory as comma-separated value (CSV) files, which are compatible with Excel. Data can be collected while the unit is running, without interruption.
  • Display: Device state, working level and radon gas concentration, battery charge level, filter status, network connectivity, date and time, firmware version, warning/error messages.
  • Data Collection: Data is retrieved via the USB port. Result files are accessible through the mass storage device native to current Windows versions. No drivers are required.
    • M601 Only: In addition to data retrieval through the USB port, live results are available via Modbus protocol over ethernet and Wi-Fi.
  • Activity LED: Blue Activity LED flashes in response to alpha decay activity.
  • Light Test: Warning light operation can be tested at any time without interrupting a job run in progress.
  • Low Power Shutdown: Automatic shut-down on low power to preserve both data integrity and battery reliability.
  • Network (M601 Only): Modbus over ethernet and Wi-Fi.
  • Calibration: Yearly radon chamber calibration is recommended.

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