* S&P rise, U.S. data bolster risk appetite * Japanese machinery orders also help mood * Tepco gains after government approves revival plan By Ayai Tomisawa TOKYO, Jan 16 (Reuters) - Japan's Nikkei average rose on Thursday morning, adding to a sharp rise in the previous session, after strong U.S. data and corporate earnings drove Wall Street stocks higher while a weaker yen bolstered market sentiment. Also helping the mood was Japanese data showing that core machinery orders jumped in November for the second straight month of gains. The Nikkei was up 0.7 percent at 15,917.06 in midmorning trade after climbing 2.5 percent on Wednesday, its biggest one-day gain in four months. The index was trading comfortably above its 25-day moving average of 15,723.06. "We are getting a boost from both overseas and domestic cues. The market has started to take risks again, and as for sentiment towards the U.S. economy, a lot of people are thinking that the weak U.S. jobs data was a one-time incident," said Isao Kubo, equity strategist at Nissay Asset Management. "Investors are relieved that U.S. growth is intact." On Wednesday the S&P 500 climbed to an all-time closing high after Bank of America reported strong earnings, while producer price data and a manufacturing survey signalled the economy was improving. The broader Topix gained 1 percent to 1,306.85, with 30 of its 33 subsectors in positive territory. Tokyo Electric Power Co soared 3.8 percent to a one-week high after the government approved a revival plan for the utility responsible for the Fukushima nuclear disaster. Index-heavyweight SoftBank Corp rose 1.4 percent and was the most traded stock by turnover. Toyota Motor Corp added 1.2 percent and Panasonic Corp gained 1.4 percent after the dollar bounced to 104.56 yen, moving within striking distance of a five-year peak. A weaker yen inflates Japanese exporters' overseas profits when repatriated. The JPX-Nikkei Index 400, a recently introduced gauge comprised of firms with high return on equity and strong corporate governance, gained 0.8 percent to 11,779.51.