"We believe the dangers outweigh the benefits. While we note that it could generate around 9000 megawatts of electricity, the long-term risks are undesirable," Matosa told delegates at the union's central executive committee meeting in Johannesburg.
In his state-of-the-nation address last month, President Jacob Zuma signalled that government planned to push ahead both with nuclear energy generation and shale gas exploration.
Matosa said the Fukushima, Japan, nuclear disaster should be a reminder of the dangers posed by nuclear energy.
"For example, hundreds of thousands of Japanese have been destructively and constantly affected by the Fukushima disaster, 160,000 fled from their homes and have been kept away by radioactivity."
In addition he said South Africa could not afford to build a R1 trillion nuclear plant which would not create jobs.
"In this context we call on government and the ANC to review their pro-nuclear stance seriously and delay any implementation towards this direction. We still believe the ANC is a listening organisation," Matosa said.
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