PARIS (Reuters) - Staff at France’s 19 nuclear plants have voted to go on strike on Thursday as part of the wider protests over the governments proposed reforms to employment laws, a CGT union official said on Wednesday, but no blackouts are expected.

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In the past week French workers led by the CGT have blocked oil refineries around the country in protest at the planned reforms aimed at making it easier for firms to hire and fire, which has led to fuel shortages in large parts of the country and long lines of cars at near-empty gas stations.

CGT energy and mining federation spokeswoman Marie-Claire Cailletaud said the strike action at nuclear plants, set to start Wednesday evening at 2000 Paris time (2 p.m. ET), will reduce power output but the reactors will not stop running.

“One cannot just turn off a nuclear plant, it is not like a thermal or hydro plant,” she said.

Staff in at least four fossil fuel-fired plants have also voted to strike, she added.

France produces about three quarters of its electricity in 19 nuclear plants run by state-controlled utility EDF, but strikes do not cause provoke blackouts because of legal limits on strike action in the nuclear industry and France’s ability to import power from neighboring countries.

During a strike in January EDF imported up to 6 gigawatts of power - equivalent to about six nuclear plants - from neighboring countries through its grid unit RTE’s extensive network of interconnections with neighboring countries.

Under internal EDF rules known as the Benat-Daures notes, staff must maintain power network tension and prevent outages during strike action.

The public may not notice a fall in nuclear power output but it incurs costs for EDF, which needs to start up more expensive fossil fuel-fired power plants and import electricity.

In 2004, when there were protests against plans to privatize EDF, unions cut power supplies to dozens of targeted locations, including parts of some cities, Paris train stations, the headquarters of political parties and the employers organization and the residences of conservative politicians.

Early last year trade union members switched off power for an hour in an entire neighborhood in Audincourt, eastern France, during a speech by Prime Minister Manuel Valls in protest at planned energy reforms.