An organization representing scientists in Japan called on the government to review its plan to dispose of spent nuclear fuel and other high-level radioactive waste deep underground, citing the geological uncertainties regarding the current method.

The Science Council of Japan also proposed keeping the waste at what it calls "temporary safe storage" sites during such a moratorium period for several decades to hundreds of years while seeking to establish the final disposal method.

The council compiled the proposal in response to a request by the government's Atomic Energy Commission to look into the current efforts to select a final repository site for high-level radioactive waste, which are at a stalemate.

"Based on the current scientific knowledge, we cannot determine a geological formation that would be stable for periods of hundreds of thousands of years… And in that case the best possible option is temporary storage," says Harutoshi Funabashi, a professor at Hosei Univ. who was involved in working out the proposal.

"This does not mean postponing the problem irresponsibly to the future. It is to secure time to find ways to more appropriately handle the matter," he adds.

The waste in temporary storage — either located underground or in a facility above ground — should be placed in such a way that it can be recovered, the council says.

During the moratorium period, the country should promote research on the stability of geological layers and improve the ability to store the waste more safely.

Funabashi says that the proposal can be applied in the event of either the government maintaining or giving up the current policy to reprocess used fuel from nuclear power plants for recycling.

Under the current plan, fuel reprocessing would produce vitrified high-level radioactive waste, which is to be placed at a final disposal site more than 300 meters underground after being stored for about 30 to 50 years for cooling.

A process to solicit local governments to host the repository site is ongoing, but not much progress has been seen.

The government is currently reviewing the country's energy policy in the wake of the Fukushima Daiichi nuclear power plant disaster, which has raised questions about continuing to expand nuclear power generation.