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)