The Tricastin nuclear site contains a power plant and a treatment facility
A French nuclear monitoring body has expressed concern at the number of leaks from French nuclear power stations in recent weeks.
The director of Criirad, an independent body, said the organisation was worried by the numbers of people contaminated by four separate incidents.
In the most recent leaks, about 100 staff at Tricastin, in southern France, were exposed to low doses of radiation.
It came two weeks after a leak forced the temporary closure of a reactor.
There has also been a 10-fold increase in the number of incidents reported by people working in the French nuclear power industry, Criirad director Corinne Castanier said.
"This type of contamination is a recurring problem. But that many people in such a short period of time, this worries us," she said.
The incident was rated at level zero on the seven-point scale used to gauge the seriousness of nuclear accidents, Ms Castanier said.
But she linked the high number of incidents to an increased pressure to deliver energy quickly and suggested that working conditions were getting worse at power facilities.
'No health problem'
Electricite de France says Wednesday's incident at Tricastin - a huge nuclear complex near the town of Avignon - was not connected to the earlier uranium leak at the plant.
The staff at Tricastin were "slightly contaminated" by radioactive particles that escaped from a pipe at a reactor complex, an EDF spokeswoman said.
The company says sensors detected a rise in the radiation level while maintenance work was being carried out at a reactor that had been shut since 12 July.
The rise in radiation prompted 97 EDF and maintenance subcontractors to be evacuated and sent for medical tests.
"Seventy of them show low traces of radioelements, below one 40th of the authorised limit," EDF said, adding that the incident would not affect people's health or the environment.
"What concerns us is less the level of the people contaminated than the number of people contaminated," EDF spokeswoman Caroline Muller told the Associated Press news agency.
Two weeks ago, the authorities had to issue a ban on fishing and water sports in two local rivers after 30 cubic metres of liquid containing unenriched uranium leaked from a broken underground pipe onto the ground and into the water.
The environment minister has since ordered tests of all France's nuclear power plants to ensure such leaks have not gone undetected elsewhere.
On Friday, energy company Areva said liquid containing slightly enriched uranium leaked at another of its sites in south-east France.
The same day, 15 EDF workers were exposed to what the company called "non-harmful" traces of radioactive elements at the Saint-Alban plant in the Alpine Isere region.
The incidents have raised questions about the state-run nuclear industry, at a time when some countries are considering nuclear energy because of the soaring price of oil, correspondents say.
France derives more than 75% of its electricity from its 59 nuclear power plants, and President Nicolas Sarkozy has recently announced plans to expand the nuclear programme.