Challenges for LIBS analysis of nuclear fuel debris at FDNPS; Effect of sample temperature and laser ablation angle on optical emission and acoustic signals from laser-induced Zirconium plasma

Batsaikhan, M.

A fiber-coupled, acoustic wave assisted (AW) microchip laser induced breakdown spectroscopy (mLIBS) system is a promising tool for remote and on-site analysis of nuclear fuel debris formed in damaged reactor vessels at Fukushima Daiichi Nuclear Power Station. In the AW-mLIBS system, the laser induced plasma optical emission is used to measure the sample's elemental composition. The acoustic signal is recorded as an auxiliary source of information for optimizing the lens-to-sample distance and visualizing the sample's surface. The currently available data regarding fuel debris's elemental composition, distribution, shape, and size are still limited. These fuel debris data are crucial to deciding further strategies and decommissioning steps for the FDNPS. Additionally, a temperature gradient exists in the reactor vessels owing to the decay heat of the nuclear fuel debris. Therefore, investigating the effect of sample temperature and laser ablation angle (LAA) is crucial to adapt the system to in-situ measurements This talk will discuss the dependence of sample temperature and LAA on the laser-induced plasma-optical emission and LIP-acoustic signal for zirconium metal, which is a part of fuel debris.