The accident at the Fukushima No. 1 nuclear power plant following the Great East Japan Earthquake and tsunami of March 11 quickly worsened and spun out of control because the U.S.-styled design for its emergency power sources had been adopted without modification 40 years ago--a source at Tokyo Electric Power Co., the plant operator, told The Asahi Shimbun.
The accident at the Fukushima No. 1 nuclear power plant following the Great East Japan Earthquake and tsunami of March 11 quickly worsened and spun out of control because the U.S.-styled design for its emergency power sources had been adopted without modification 40 years ago--a source at Tokyo Electric Power Co., the plant operator, told The Asahi Shimbun.
In the U.S. design, emergency power generators are installed underground to guard against tornadoes and hurricanes. The Fukushima plant was, however, swamped when the tsunami rose more than 10 meters above the normal sea level along the coast and knocked out its power supply in the blink of an eye.
In the U.S. nightmarish scenario, used in the 1960s to draw up protection measures against nuclear plant disasters, violent winds, as strong as 360 kph, strike the plant. A giant tree growing nearby, uprooted and airborne, crashes through the walls of a reactor building like a missile and destroys the emergency power sources. The emergency power generator is located in a turbine building, which has thinner walls than the reactor building next door. Thus, it was deemed safer to install the emergency power generator underground to protect it from a "tree missile," explained the TEPCO source.
General Electric Co. and other U.S. enterprises took the helm in building the Fukushima No. 1 plant's No. 1 reactor, which was TEPCO's first nuclear reactor. The contract was called "full turn-key," which meant that TEPCO had only to turn the key to start operations. All technical questions were left to the U.S. contractors.
Design of the No. 2 and newer reactors, where Toshiba Corp., Hitachi Ltd. and other Japanese manufacturers had greater roles to play, also basically followed the playbook of the No. 1 reactor. There was not enough time to review the design to account for different natural disasters in Japan and the United States, including tsunami.
"We built them the way they told us to build them, because they said they wouldn't guarantee safety unless we built them according to the U.S. specifications," recalled a former senior official at the former Ministry of International Trade and Industry.
Forty years have passed since the Fukushima No. 1 reactor began operations, but the design was never reviewed.
"Emergency power generators are heavy and they cause vibrations. Their relocation would have meant radical redesign of entire buildings," said the TEPCO source.
As a result, 10 emergency power generators, a significant part of the total 13 at the No. 1 through No. 6 reactors of the Fukushima No. 1 power plant, were installed in the first basement. Only one generator, installed on the ground floor of the No. 6 reactor, escaped water damage when the tsunami hit. All power sources to cool down the nuclear reactors were lost, and the No. 1 through No. 3 reactors, which were operating at the time, suffered meltdowns.
Around Japan, the U.S.-styled design was adopted at other nuclear power plants, such as the Hamaoka nuclear power plant in Shizuoka Prefecture, where all operations have been halted at the request of Prime Minister Naoto Kan. As the emergency power generators were located on the ground floor of the reactor buildings, Chubu Electric Power Co., the plant's operator, installed new power generators on building rooftops as an emergency measure.
Direct transplant of technologies from overseas is a pitfall inherent to Japan's technological philosophy, said economic analyst Katsuto Uchihashi, who is familiar with the introductory phase of nuclear technologies.
"Development of technologies in postwar Japan went either of the two ways: try to develop them independently by learning from other countries, or rely entirely on other countries in introducing them. The Fukushima No. 1 power plant typically illustrates the latter option. People relied totally on a U.S. design without considering different natural conditions. The idea of bringing in technologies as a whole is a problem common to other fields, including space development and semiconductors," he said.