Toshiba Corp Chairman Shigenori Shiga is ready to step down to take responsibility for the huge writedowns looming over the Japanese group's U.S. nuclear power unit Westinghouse Electric Co LLC, the Nikkei business daily reported. Shiga was chairman of Westinghouse when the unit booked charges of $930 million in fiscal 2012 and $390 million in fiscal 2013, which Toshiba failed to flag at the time in violation of the Tokyo bourse's disclosure rules. The Japanese conglomerate's nomination committee will decide on the matter of Shiga's resignation and an announcement could come as soon as Feb. 14, the Nikkei reported earlier.