With Japan’s failure so far to contain radiation leaks from the deteriorating seaside Fukushima Dai-ichi nuclear power plant, suggestions have poured in from around the world offering fixes to the problem.

Some of the suggestions:

Drones — Japanese officials have used manned helicopters and water cannons to dump tons of water on the most troubled reactors, but there is a risk of radiation exposure to humans operating the equipment. Some experts have wondered whether drones could do the job.

The problem is that the U.S. Air Force’s Predator and Reaper drones are high-speed aircraft designed to fly at high altitudes, not low altitudes. Nor do the planes have the ability to hover like helicopters or carry heavy loads.

Firefighting C-130s — The U.S. Air Force has wide-body transport planes that are configured for firefighting, and are often used to put out forest fires.

The specially configured transports can drop water or fire retardant, and they can discharge a load — 3,000 gallons weighing 14 tons — in less than five seconds, according to the Air Force fact sheet. But a crew is required to operate the plane, raising the same concern about radiation exposure.

Firefighting ships — Some have suggested using special firefighting ships. One person attached a photo in a posted comment to a Washington Post story about solutions.

But U.S. Navy officials say they do not have any ships that would be able to project water so far away.

Dry ice — Many of the “dozens” of suggestions that have been called in or sent electronically to the Nuclear Regulatory Commission involve dry ice, according to spokeswoman Holly Harrington. Dry ice is basically solid carbon dioxide and would work as a cooling agent, experts said.

But it would probably have to be dropped on the stricken reactors from a helicopter, and “you don’t want to drop something solid and big, because it could fall and break the fuel more,” said Lake Barrett, a retired nuclear engineer who led emergency operations at Three Mile Island during that Pennsylvania facility’s partial core meltdown in 1979.

Also, even if the dry ice could be dumped safely, there is a risk of thermal shock if the reactor is cooled too quickly. “When you’re dealing with something very, very hot, you want to bring (the temperature) down quickly, but not too quick,” Barrett said. “… Carbon dioxide might be too fast.”

Lead shot and sand — If authorities are unable to use water to cool the overheating reactors or the pools above the reactors — which also need to be covered with water to prevent overheating and massive releases of radiation — they may have to resort to using lead shot mixed with sand or some other earthen materials to absorb cesium, the most toxic of the radioactive isotopes, Barrett said. But those materials are much harder to clean up later on than water, he said.

Pressurized dome — One scientist based in Israel is proposing that Japan construct a giant, pressurized dome made of plastic to stop the spread of radioactive dust. So far, no countries appear to have tested the concept in application, he said.