"Tokyo Electric Power Co. detected signs of nuclear fission at its crippled Fukushima atomic power plant, raising the risk of increased radiation emissions. No increase in radiation was found at the site and the situation is under control, officials said."

"The company, known as Tepco, began spraying boric acid on the No. 2 reactor at 2:48 a.m. Japan time to prevent accidental chain reactions, according to an e-mailed statement today. The detection of xenon, which is associated with nuclear fission, was confirmed today by the Japan Atomic Energy Agency, the country’s atomic regulator said.

'Given the signs, it’s certain that fission is occurring,' Junichi Matsumoto, a general manager at Tepco who regularly talks to the media, told reporters in Tokyo today. There’s been no large-scale or sustained criticality and no increase in radiation, he said."

Tsuyoshi Inajima and Yuji Okada report for Bloomberg November 2, 2011. [2]