The Three Gorges Dam must stand the test of time with aplomb for generations to come, according to China's top advisory body seeking to improve the world's largest hydroelectric project's quality control.
China must equip its future generations with an eligible Three Gorges Project -- under construction since 1994 -- said Qian Zhengying, vice-chairwoman of the Chinese People's Political Consultative Conference.
"The quality of the project should be good enough to pass the test of history," Qian, the former minister of water resources, said in her latest speech following a quality inspection of the site.
"During the past three years, concrete placement in the project has not been first class, causing a variety of related accidents and drawbacks, though the concrete process has improved compared with previous years," Qian said in her report, released Thursday.
Qian, head of the expert group, made it clear that cracks have appeared since winter in the mammoth dam -- with a crest elevation of 185 metres and a length of 2,309 metres -- which "must be repaired fastidiously."
Such cracks, mainly caused by drastic temperature changes, have also been discovered in the project's permanent ship-locks and ship-lifts, the largest of their type in the world.
The cracks have aroused strong public concern about the quality of the project, according to Qin and Pan Jiazheng, an academician of the Chinese Academy of Sciences and the Chinese Academy of Engineering.
Small cracks with a maximum width of 1.25 millimetres and depth of 2.5 metres "are inevitable in all of the world's hydroelectric projects," said Lu Youmei, general manager of the Yichang-based China Yangtze Three Gorges Project Development Corporation (CTGPC).
Lu was confident the cracks will not affect the project's quality and its future safe operation after necessary treatments, according to China News Service.
He promised such cracks would not get any worse with temperature fluctuations in the near future.
Qian said she hopes measures can be taken this winter and next spring to prevent more cracks from appearing.
Senior quality-control experts should have been responsible for preventing such accidents, Qian said, disclosing that, since 2000, the experts stopped keeping concrete warm while pouring -- a sure measure to prevent cracks occurring -- during the dam's construction.
During their week-long quality inspection on Yichang in Central China's Hubei Province, Qian also reminded authorities responsible for the project's construction to be cautious about other technical issues in the days ahead.
For example, comprehensive quality-control should be carried out in the project's powerhouse, design and installation of its turbopower generators, as hydropower generated by the project will be vital to its future economic efficiency.
By the end of the year, all the dam sections in the second phase (1998-2003) of the project's construction are expected to reach the dam's crest. Around 7.5 million cubic metres of concrete placement, 57,000 tons of metal works, and mechanical and electric embedded parts are expected to be completed, experts claim.
Next year is expected to achieve a series of major objectives, including the realization of the initial stage reservoir storage, power generating the first batch of units and putting permanent ship-locks into operation.
Meanwhile, 7.51 million cubic metres of earth and rock embankment, 1.78 cubic metres of concrete placement and 30,300 tons of metal works, and mechanical and electric embedded parts, are scheduled to be executed next year, the last year of the second phrase.
(China Daily April 12, 2002)
