A safety task force says nuclear power plants in the U.S. do not pose immediate safety risks to the public, but suggests reforms are needed in order to plan for unexpected catastrophes in the wake of the nuclear disaster in Japan.

In a report to the U.S. Nuclear Regulatory Commission, the task force recommends that the 104 U.S. nuclear power plants implement tougher safety standards for disasters the facilities were not originally designed to withstand. A three-month investigation found that some facilities were not built to survive natural disasters, such as earthquakes and floods.

The report calls for improved backup power capabilities in the case of a prolonged loss of electricity. It also calls for tougher standards for backup water supplies that cool reactors in the case of a meltdown.

The safety task force was formed after the disaster at Japan's Fukushima Daiichi nuclear plant, which has been leaking radiation into the air, ground and sea since a March 11 earthquake and tsunami. The disasters knocked out the cooling systems at Fukushima, which led to a meltdown in three of its reactors.

The accident is the world's most severe nuclear crisis since the 1986 Chernobyl disaster.