Cesium-134 and -137 are prevalent, long-lived, radio-toxic
contaminants
released into the environment during nuclear accidents. Large quantities
of insoluble, respirable Cs-bearing microparticles (CsMPs) were released
into the environment during the Fukushima Daiichi nuclear accident.
Monitoring for CsMPs in environmental samples is essential to understand
the impact of nuclear accidents. The current detection method used
to screen for CsMPs (phosphor screen autoradiography) is slow and
inefficient. We propose an improved method: real-time autoradiography
that uses parallel ionization multiplier gaseous detectors. This technique
permits spatially resolved measurement of radioactivity while providing
spectrometric data from spatially heterogeneous samples—a potential
step-change technique for use after nuclear accidents for forensic
analysis. With our detector configuration, the minimum detectable
activities are sufficiently low for detecting CsMPs. Further, for
environmental samples, sample thickness does not detrimentally affect
detector signal quality. The detector can measure and resolve individual
radioactive particles ≥465 μm apart. Real-time autoradiography
is a promising tool for radioactive particle detection.