Tsunami Hazards for Nuclear Power Plants: Mass Failures, Uncertainty, and Warning

Abstract

The 2011 Tohoku tsunami portends the beginning of a new era in tsunami hazard assessment. A new level of detail will be demanded to secure every valve, pipe, pump or fuel tank at nuclear power plants (NPPs). Three issues stand out at the dawn of this new era: earthquake magnitudes, landslide tsunamis, and probabilistic tsunami hazard assessment (PTHA). The challenges of estimating a maximum earthquake magnitude along some margin continue to be studied. While any potential role of mass failures and landslide tsunamis in the Tohoku event is unknown now, factoring for these tsunami-sources is essential to hazard assessment, and their full impact needs to be found. Armed with a thorough set of tsunami hazards, a probabilistic framework is needed, one that can reach comfortably to 50,000 year events, and quite possibly to volcanic events with 100,000 year or longer recurrence intervals. Effectiveness will ultimately be measured by NPPs that withstand tsunami attack and resume operations shortly thereafter, exactly as planned and with no surprises.