The government's commission on atomic energy on Friday officially adopted its plan to resume operations at Monju, Japan's prototype fast-breeder nuclear reactor that was shut following a major coolant leak in 1995.

The Atomic Energy Commission, which operates under the Prime Minister's Office, also decided to keep Monju in operation for at least 20 years.

The decisions were made as part of a long-term plan for the research and development of nuclear power adopted by the commission the same day. The long-term plan is now state policy.

Science and Technology Agency chief Tadamori Oshima, who heads the panel, will visit the reactor in Tsuruga, Fukui Prefecture, on Sunday to brief local authorities on the long-term plan and to seek their approval for restarting Monju.

After they give their consent, it will take at least three years before Monju can be reopened.

Oshima told reporters after a Cabinet meeting Friday that the commission agreed on the need to develop technologies for fast-breeder reactors. "We'd like to prepare for future developments by examining technological problems," he said.

On Friday, Motohide Konaka, a senior official at the science agency chief's secretariat, visited Fukui Gov. Yukio Kurita to explain the panel's decision. Kurita only responded that he would like to talk further with Oshima on Sunday.

Fukui Prefecture officials said the governor will consider various factors, including national government spending plans to boost the local economy, before he makes a final decision whether to accept Monju's reopening.

The Japan Nuclear Cycle Development Institute, which operates the reactor, plans to ask the Fukui prefectural and the Tsuruga city governments to allow safety examinations at the plant in preparation for conducting improvement work, sources close to the institute said.

Yasumasa Togo, chief of the institute, said in a statement that the commission has decided that it is important for the Monju reactor to "prove its reliability as a power plant."

"We'll resume its operations at the earliest possible date with the understanding of the local community as well as society and make utmost efforts for (nuclear) research and development," he said.

On Dec. 8, 1995, some 640 kg of sodium, used as a coolant, leaked from a duct in Monju, and led to a fire.

No personnel at the plant or local residents were injured or exposed to high levels of radiation. But the accident, allied to subsequent revelations of coverup attempts by its then operator, Power Reactor and Nuclear Fuel Corp., dented people's trust in the government's nuclear power policy.

The long-term plan is the ninth of its kind and will be the cornerstone of the nation's nuclear power policy for the next five years. The first plan was compiled in 1956.

The plan runs counter to a trend among a number of countries -- including Britain, Germany, France and the United States -- to scrap projects for fast-breeder reactors for political, technical or financial reasons.

It also offers continued support for the nation's nuclear fuel cycle policy, which utilizes plutonium collected from spent nuclear fuel in the process of fuel reprocessing.

Unlike light-water reactors that are fueled by uranium, fast-breeder reactors operate on plutonium-uranium mixed oxide fuel and produce a greater amount of plutonium than they consume.

The plan also urges the private sector to start storing used nuclear fuel by 2010 and to begin the disposal of high-level radioactive waste underground from the 2030s to mid-2040s.