2018, over a third of Japan's 10 metric tons of domestically held plutonium is stored at Rokkasho. Economic aspects Since 1993 there has been US$20 billion invested in the project, nearly triple the original cost estimate. A 2011 estimate put the cost at US$27.5 billion. Protests In May 2006, an international awareness campaign about the dangers of the Rokkasho reprocessing plant, Stop Rokkasho, was launched by musician Ryuichi Sakamoto. Greenpeace has opposed the Rokkasho Reprocessing Plant under a campaign called "Wings of Peace – No more Hiroshima Nagasaki", since 2002 and has launched a cyberaction to stop the project. Consumers Union of Japan together with 596 organisations and groups participated in a parade on 27 January 2008 in central Tokyo against the Rokkasho Reprocessing Plant. Over 810,000 signatures were collected and handed in to the government on 28 January 2008. Representatives of the protesters, which include fishery associations, consumer cooperatives and surfer groups, handed the petition to the Cabinet Office and the Ministry of Economy, Trade and Industry. Seven consumer organisations have joined in this effort: Consumers Union of Japan, Seikatsu Club Consumer's Co-operative Union, Daichi-o-Mamoru Kai, Green Consumer's Co-operative Union, Consumer's Co-operative Union "Kirari", Consumer's Co-operative Miyagi and Pal-system Co-operative Union. 'Experts including Frank von Hippel, a Princeton University theoretical physicist, have urged Japan to stop spent fuel reprocessing.', reported The Japan Times. The fundamental objection to reprocessing—the separation of plutonium from spent power reactor fuel—is that the plutonium is a nuclear explosive. Despite nuclear industry claims to the contrary, it usable for powerful nuclear weapons. A plant like Rokkasho can separate several tons of plutonium per year. a nuclear weapon requires only several kilograms. 2011 Tōhoku earthquake and tsunami In June 2008, several scientists stated that the Rokkasho plant is sited directly above an active geological fault line that could produce a magnitude 8 earthquake. But Japan Nuclear Fuel Limited stated that there was no reason to fear an earthquake of more than magnitude 6.5 at the site, and that the plant could withstand a 6.9 quake. After the Tōhoku earthquake (magnitude 9.1) in March 2011, the plant ran on emergency power provided by backup diesel generators. The emergency generators were not intended for long-term use. Reportedly there are about 3,000 tons of highly radioactive used nuclear fuel stored in Rokkasho at the current time. Japanese radio reported on 13 March that 600 liters of water leaked at