This may well be the case during normal operation. It seems the worry, however, is that seismic activity etc. could lead to a steam explosion and release of

This may well be the case during normal operation. It seems the worry, however, is that seismic activity etc. could lead to a steam explosion and release of radioactive gases if the plant failed to shut down. (I’m not a nuclear engineer and the article doesn’t make the assessed risks 100% clear, though.)