MOSCOW, May 15 (RIA Novosti) - The third reactor at the Leningrad nuclear power station, located in northwest Russia, was shut down by an emergency protection system on Thursday.

"The reactor was being tested after having been [recently] modernized and was operating at a half capacity of 500 MW when the emergency automatic shutdown system went into effect," Russia's state-controlled nuclear power corporation Rosenergoatom said.

Rosenergoatom added that there was no radiation leak from the unplanned shutdown.

The Leningrad NPP restarted the sixth turbine generator of its third reactor on May 13. Rosenergoatom had earlier planned to fully restore the capacity of the reactor by the end of this week.

The plant, located 80 km west of St. Petersburg, has four 1,000 MW units with graphite-moderated reactors.