HUNTSVILLE, Alabama -- U.S. regulators studying the nuclear disaster at the Fukushima plant in Japan have recommended several steps American nuclear plant owners should take to improve public safety, according to a study issued Wednesday.

The three reactors at Browns Ferry nuclear plant near Athens share the same design as Fukushima, and a number of issues raised in the Nuclear Regulatory Commission report could affect Browns Ferry.

The study recommends better earthquake and flood readiness, better preparation for an extended power loss, independent cooling systems for stored spent fuel rods and improved venting for the emergency release of radioactive steam.

The study said there is no imminent danger from any of the 104 operating U.S. reactors, but it also found the current "patchwork" of regulations has resulted in some safety measures not being given sufficient weight by regulators or plant owners.

Ray Golden, a spokesman for the Tennessee Valley Authority's nuclear division, said the utility has been looking at issues raised by Fukushima since the accident.

"Immediately following the event, TVA created a response team and we've already begun implementing various activities to make our plants safer," Golden said. "What we've done lines up quite closely with the NRC recommendations."

Meanwhile, the Union of Concerned Scientists also issued a set of recommendations Wednesday that went further than the NRC. The Washington, D.C. group urged regulators to require spent fuel rods to be moved into dry cask storage containers rather than leaving significant numbers of fuel rods in pools inside reactor buildings.

The UCS said the Fukushima plant had between 200 and 550 fuel assemblies in each of its spent fuel pools, while the average U.S. plant has about 3,000 per pool.

The group also said the current 10-mile evacuation barrier around nuclear plants is not large enough and should be extended.

David Lochbaum, director of the Union of Concerned Scientists' Nuclear Safety Project, called for the NRC to move swiftly while acknowledging the NRC report found there weren't any immediate safety implications.

"On the flipside, that doesn't mean there can be an open-ended timeframe for resolving these issues," Lochbaum said. "It's a high stakes poker game. The public will take a dim view if there is a disaster at a plant when the government knew what needed to be fixed and we didn't do it. As (UCS senior scientist Ed Lyman) says, 'it would mean the end of nuclear power.' "

The Fukushima plant melted down and released significant radiation after Japan was hit by an earthquake and a tsunami in March. The resulting loss of power meant plant operators couldn't cool the reactors. The melting reactors produced hydrogen, which caught fire and exploded, leading to a radioactive release that is still being measured.

Golden said TVA's response with new equipment and other changes will cost the utility several million dollars this year and "tens of millions" next year.

All three of Browns Ferry's reactors were operating at full power Wednesday, Golden said. TVA hopes that any future changes ordered by the NRC could be handled during a regular refueling outage, but Golden said it is too early to know what will be required.

"At some future end state plants will be stronger and more safe as a result of this oversight," Golden said. "The NRC is doing this, the (nuclear power) industry is doing their own evaluation and offering its own recommendations, and TVA is doing the same."