InSAR as a tool to monitor nuclear decommissioning – a case study across the Fukushima Daiichi Nuclear Power Plant, Japan

The Fukushima Daiichi Nuclear Power Plant, Japan, underwent a series of sequential meltdowns in 2011 related to the magnitude 9.0 earthquake and tsunami of the same year - causing the world’s second ‘Level 7’ nuclear event after Chernobyl. Japan and the Tokyo Electrical Power Company (TEPCO) have been proactive in taking steps towards decommissioning the now hazardous site, with a clean-up timeline continuing work for another 30-40 years. However, this creates a need for long-term monitoring strategies that mitigate radiation hazards for the personnel involved with the decommissioning. Remote sensing can fill this emerging need, more specifically with Interferometric Synthetic Aperture Radar (InSAR).

InSAR can monitor ground and structure stability with millimetre scale accuracy, as well as create a historical baseline for past movement using data from ESA’s Sentinel-1 satellite mission. Here we show the applicability of InSAR monitoring across the Fukushima plant using Sentinel-1 data spanning October 2015 to October 2019. Our results clearly show an uplift signal of ~75 mm around the reactor, during the time period directly coinciding with the implementation of a perimeter ice wall which was constructed to mitigate groundwater leeching.

This study demonstrates the benefits of InSAR to monitor ground stability in near-real time, and across a wide area, without the need for direct interaction with such a hazardous site. Via this study, we have demonstrated that InSAR is a powerful technique for monitoring potential ground stability issues at highly hazardous sites, with applications for the engineering, oil and gas, and mining sectors.