On-Line Monitoring of Radiocarbon Emissions in a Nuclear Facility with Cavity Ring-Down Spectroscopy

There
are currently
no suitable methods for sensitive automated
in situ monitoring of gaseous radiocarbon, one of the main sources
of radioactive gas emissions from nuclear power plants. Here, we present
a transportable instrument for in situ airborne radiocarbon detection
based on mid-infrared cavity ring-down spectroscopy and report its
performance in a 1-week field measurement at the Loviisa nuclear power
plant. Radiocarbon is detected by measuring an absorption line of
the 14CO2 molecule. The time resolution of the
measurements is 45 min, significantly less than the few days’
resolution of the currently used technique, while maintaining a comparable
sensitivity. The method can also assess the prevalence of radiocarbon
in different molecular species in the airborne emissions. The optical
in situ monitoring presented is a completely new method for monitoring
emissions from nuclear facilities.