* From mid-January only 4 out of 58 reactors will be offline
* EDF set to get through winter without power shortages
* Power prices fall back sharply as supply worries ease (Adds detail on outages)
By Geert De Clercq and Bate Felix
PARIS, Dec 12 (Reuters) - French state-controlled utility EDF confirmed on Monday that seven nuclear reactors shut down for safety checks would be up and running again by the end of December and there would be no problem with power supplies this winter.
The company said its reactors were safe and also confirmed revised 2016 targets for nuclear production of 378-385 terawatt hours, as well as for its core earnings.
Grid operator RTE said in a report on Saturday that three of the seven reactors offline - Gravelines 2, Dampierre 3 and Tricastin 3 - would resume production from Dec. 20 and that four more would restart before Dec. 31. EDF confirmed the report.
The seven reactors are among 12 that have been slated for inspections under orders from the nuclear regulator ASN following the discovery of high carbon concentrations, which could weaken their steel.
Another four of the 12 earmarked for checks - Fessenheim 1, Gravelines 4, Civaux 1 and Tricastin 2 - will go offline this month and resume production before Jan. 15, EDF officials said.
"For the January and February months we will be in a configuration that is similar to previous years and there is no reason to think we will not have the power required to meet customers' needs," Dominique Miniere, head of EDF's French nuclear network, told reporters on a call.
He said EDF aimed to have available nuclear power output at more than 90 percent of total capacity then.
From mid-January, EDF will only have four of its 58 reactors offline, for reasons not related to the ASN investigation. These plants are Bugey 5, Paluel 2, Fessenheim 2 and Gravelines 5.
The longest outage will be at Paluel 2, where a 465 tonne steam generator was dropped onto the reactor floor during maintenance in April. It is due to restart at the end of November next year.
Miniere said the nuclear industry worked within wide safety margins and despite the ASN investigation there was still a wide margin left. "Our reactors are safe," he said.
French power prices have fallen sharply in recent days as worries about the security of electricity supplies over winter eased.
Between early September and mid-November, year-ahead French power futures jumped from about 32 euros to nearly 50 euros as markets worried that the reactor outages could lead to power shortages.
They have fallen back to about 36 euros since the start of the month. (Reporting by Geert De Clercq and Bate Felix; editing by David Evans and David Clarke)