TOKYO, July 18 (Reuters) - Japan's Nikkei share average opened higher on Wednesday, buoyed by a rise in U.S stocks as several blue chips beat earnings expectations and U.S. Federal Reserve Chairman Ben Bernanke kept alive hopes for more easing. The Nikkei rose 0.4 percent to 8,792.91, while the broader Topix was also 0.4 percent up at 746.22.