Japan - Fukushima Ten Years On: Lessons Learned
Ian McKinley, Shinichi Nakayama and Susie Hardie consider how recovery has progressed at Fukushima Daiichi and what lessons can be learned for the future
THE GREAT TOHOKU EARTHQUAKE AND tsunami of 11 March 2011, which devastated north-eastern Japan, with the direct loss of over 18 000 lives and a legacy of displaced populations, damaged infrastructure and environmental pollution, has been ranked as the costliest natural disaster (≈ $300 billion) in world history. The damage to coastal infrastructure was immense, with impacts from loss of services, costs of replacement and remediation of resultant pollution – including that from the destruction of over 70 sewage treatment plants and damage to over 3300 facilities handling oil and potentially toxic materials from the petrochemical industry. However, internationally this is not well known as most focus has been on only one of these incidents – the reactor core melts at Fukushima Daiichi nuclear power station.
The huge, magnitude 9, undersea megathrust earthquake (largest recorded in Japan and fourth largest worldwide since records began in 1900) did little damage to the working reactors on the Fukushima Daiichi site, but it did knock out off-site power supply and extensively damaged regional communication, transport and monitoring infrastructure. In addition, the associated tsunami resulted in wave heights estimated to be around 15m, far larger than the reference maximum value (5.7m) and sufficient to flood the site and knock out all backup generators for units 1-4. The combination of the earthquake and tsunami resulted in a “perfect storm”, leading to core meltdown of three reactors (units 1-3) and subsequent hydrogen explosions generated by water-cladding-fuel interaction (including in the linked unit 4, which was defueled at the time), resulting in the release of volatile radionuclides that were subsequently deposited over land and sea.