Radiocarbon Dioxide detection based on Cavity Ring-Down Spectroscopy and a Quantum Cascade Laser

TL;DR

This paper demonstrates a sensitive, compact, and robust cavity ring-down spectroscopy method using a quantum cascade laser for detecting radiocarbon dioxide at very low concentrations, suitable for nuclear safety applications.

Contribution

It introduces a novel mid-infrared spectroscopic technique with a quantum cascade laser for highly sensitive radiocarbon detection in CO2, suitable for on-site nuclear monitoring.

Findings

Detects radiocarbon dioxide at 50 ppt isotopic ratio

Achieves detection sensitivity of 2 Bq/m$^3$ in air

Instrument is compact, robust, and suitable for field use

Abstract

Monitoring of radiocarbon ($^{14}$C) in carbon dioxide is demonstrated using mid-infrared spectroscopy and a quantum cascade laser. The measurement is based on cavity ring-down spectroscopy, and a high sensitivity is achieved with a simple setup. The instrument was tested using a standardised sample containing elevated levels of radiocarbon. Radiocarbon dioxide could be detected from samples with an isotopic ratio $^{14}$C/C as low as 50 parts-per-trillion, corresponding to an activity of 5 kBq/m$^3$ in pure CO$_2$, or 2 Bq/m$^3$ in air after extraction of the CO$_2$ from an air sample. The instrument is simple, compact and robust, making it the ideal tool for on-site measurements. It is aimed for monitoring of radioactive gaseous emissions in nuclear power environment, during the operation and decommissioning of nuclear power plants. Its high sensitivity also makes it the ideal tool for the detection of leaks in radioactive waste repositories.