Detection of Gadolinium in Surrogate Nuclear Fuel Debris Using Fiber-Optic Laser-Induced Breakdown Spectroscopy under Gamma Irradiation

• Published in: Applied sciences 2020-12, Vol.10 (24), p.8985
• Main Authors: Nakanishi, Ryuzo, Saeki, Morihisa, Wakaida, Ikuo, Ohba, Hironori
• Format: Article
• Language: English
• Subjects: Calibration; Detritus; Emission spectra; Fiber lasers; fiber-optic; Food irradiation; Gadolinium oxide; Gadolinium oxides; Gamma irradiation; Gamma rays; Irradiation; Laser induced breakdown spectroscopy; Lasers; nuclear fuel debris; Nuclear fuels; Nuclear power plants; Nuclear reactors; Optical fibers; Optics; Plasma; Power plants; Qualitative analysis; Radiation; Radiation damage; Radiation effects; rare earth elements; Spectroscopy; Spectrum analysis
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app10248985

Fiber-optic laser-induced breakdown spectroscopy (FO-LIBS) was applied to a qualitative and quantitative analysis of gadolinium (Gd) in mixed oxide samples, simulating nuclear fuel debris in the damaged reactors of the Fukushima Daiichi Nuclear Power Station. The surrogate debris was prepared from mixed oxide materials containing Gd2O3, with varying Gd concentrations. The emission spectra of the surrogate debris show that the optical emission lines at 501.5 nm and 510.3 nm are suitable for Gd detection in the nuclear fuel debris. LIBS measurements were further performed under gamma irradiation (0–10 kGy/h), resulting in a decrease in spectral intensities due to radiation-induced damage to the optical fiber. For quantification of Gd, robust calibration curves against gamma irradiation were established from the intensity ratio of Gd (501.5 nm)/Ce (474.5 nm) emission lines, yielding the limits of detection for Gd in the range of 0.03–0.08 wt%. These results demonstrate that FO-LIBS is a potential tool for in situ and remote analysis of nuclear fuel debris.