Incorporating civilian radioxenon background estimates in anomaly detection.

Area of Science:

• Nuclear Science and Engineering
• Environmental Monitoring
• Radiochemistry

Background:

• Discerning anomalous radioxenon activity concentrations from elevated backgrounds remains a challenge for nuclear explosion screening.
• Current research focuses on comparing sample concentrations to estimated atmospheric backgrounds from nuclear facilities.

Purpose of the Study:

• To develop and evaluate a new approach for detecting anomalous radioxenon concentrations.
• To determine if plausible release rates from facilities can explain observed radioxenon measurements.

Main Methods:

• Estimating sample concentrations using time-varying radioxenon release rates derived from optimization techniques.
• Constraining facility release rates to plausible levels based on historical data or facility knowledge.
• Applying a case study using radioxenon data from three western European locations in 2021, considering releases from 77 potential sources.

Main Results:

• The new approach identified fewer anomalous samples than the current International Monitoring System (IMS) activity concentration-level rule.
• The optimization technique successfully constrained release rates to plausible amounts.

Conclusions:

• The developed method offers a more refined way to identify anomalous radioxenon concentrations.
• This approach enhances the ability to distinguish between routine and potentially non-routine releases in atmospheric monitoring.