I blogged earlier about what Tohoku Electric and other utilities operating nuclear power plants are doing to prepare for earthquake and tsunami emergencies such as were experienced at Fukushima Daini and Daiichi.
TEPCO has released details of large tide walls that would protect the Kashiwazaki Kariwa Nuclear Power Station and its seven reactors from tsunamis. Kashiwazaki Kariwa is the largest nuclear power plant in the world. It was was off line for two to three years after the 2007 Niigata-Chuetsu earthquake caused damage to the plant, but not to the reactors.
Based on the experience at Fukushima, TEPCO says it has installed facilities on the upland part of the site to provide backup power and water injection to reactors and spent fuel pools to ensure cooling function in the event of a tsunami flooding the reactor buildings. TEPCO is also proposing to install tide barriers with watertight doors at Kashiwazaki Kariwa units 1 to 4. The intention is to prevent flood waters from entering the nuclear reactor buildings where power supply facilities and emergency diesel electric power generators are installed. Reportedly at Fukushima Daiichi backup generators were rendered inoperable by the 14 m tsunami and fuel tanks were washed away.