A nuclear reactor in northeastern Japan was halted Monday for checks, the plant operator said, just days after it became the first to restart in the region since the 2011 earthquake and tsunami disaster. Tohoku Electric Power Co. is facing difficulties in sending in a device to confirm the condition of the No. 2 reactor at the Onagawa plant in Miyagi Prefecture. The reactor last Tuesday joined a dozen others in the country that have been rebooted after meeting more stringent safety standards imposed in the wake of the Fukushima Daiichi nuclear power plant crisis, triggered by the quake-tsunami…