Radiation surrounding Japan's crippled Fukushima nuclear plant has increased 18-fold following a report last month that radioactive water had leaked into the ground around the plant, which was badly damaged in a 2011 earthquake and tsunami.

Tokyo Electric Power Co., which owns the Fukushima Dai-ichi plant, reports that radiation around the site is at 1,800 millisieverts per hour, a level that Reuters says is "enough to kill an exposed person in four hours."

Previously, the utility, also known as Tepco, said the leaking water was at around 100 millisieverts per hour.

The BBC says:

"In addition, Tepco says it has discovered a leak on another pipe emitting radiation levels of 230 millisieverts an hour.The plant has seen a series of water leaks and power failures."

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