Tokyo Electric Power Company (Tepco) has released details of steps it is taking to protect the seven-unit Kashiwazaki Kariwa nuclear power station from future tsunamis. The company has also lifted a program of rolling power blackouts.
Kashiwazaki Kariwa was unaffected by the 11 March earthquake and tsunami, although the plant’s seven reactors were previously off line for two to three years following the 2007 Niigata-Chuetsu earthquake which caused damage to the site but did not damage the reactors themselves. While the units were off line, work was carried out to improve the plant’s earthquake resistance.
Now, in the light of recent experience at Fukushima, Tepco is proposing to design and install a system of tide barriers with watertight doors at Kashiwazaki Kariwa units 1 to 4. In addition, the company says it has installed facilities on the upland part of the site to provide backup power and water injection to both reactors and spent fuel pools, and taken measures to ensure cooling functions in the event of tsunamis flooding the reactor buildings.
“We plan to prevent the waves from flooding inside the nuclear reactor buildings where important facilities in terms of safety such as power supply facilities and emergency diesel electric power generators are installed and to ensure the fundamental safety in the station,” the company says. It promises to design the tide barriers and begin their construction in “a rapid manner.”
Rolling blackouts lifted
Tepco has lifted the program of rolling blackouts it has been following since 14 March. According to a company, the supply-demand balance has now improved significantly, with peak daily demand currently about 20% down on this time last year. This is thanks to efforts by consumers to conserve electricity, and also a slowing of corporate activity since the 11 March earthquake and tsunami devastated eastern Japan.
Tepco estimates that peak demand will continue to decrease over the next two months as temperatures start to rise and with the approaching Golden Week holiday period, meaning it should have enough capacity to meet demand with some to spare. However, should electricity demand increase rapidly due to unexpected weather conditions or problems with restored power plants, the blackouts may have to be re-introduced.
The company is working to enhance supply capacity in anticipation of annual peak demand during the summer.
Researched and written by World Nuclear News