TOKYO (Reuters) - Japan's Kansai Electric Power Co on Saturday shut down one of its reactors due to technical glitches, worsening a tight power supply that is stifling manufacturers. The No.1 reactor at Kansai's Ohi plant, located 350 km (220 miles) west of Tokyo, was manually closed for checks after pressure in a tank containing boric acid water fell for a time on Friday night for unknown reasons, a company spokesman said. The pressure has since come back up to the normal range, and no radiation leakage has occurred. "Power supply (in western Japan) has been quite tight in the first place. This problem at Ohi's No.1 unit is making it worse," Nuclear Minister Goshi Hosono told reporters.