The government will join hands with Russia to build a facility to store reactor components from dismantled nuclear submarines on the outskirts of Vladivostok in hopes of preventing radioactive pollution in the Sea of Japan, government sources said Sunday.

Japan will also support Moscow by operating a new radiation assessment system on a trial basis in the area where the submarines' reactor components will be dismantled for semipermanent storage at the facility.

The 6-hectare facility will be able to store components from up to 100 dismantled submarines. The project carries an estimated price tag of $71 million, making it one of the largest Russian denuclearization projects with Japanese involvement.

Tokyo plans to provide $5 million to finance the experimental operation of the radiation assessment system, under which radiation data will be collected from the sea and land near where the submarines are dismantled.

The Foreign Ministry's parliamentary secretary, Katsuyuki Kawai, who visited the site July 9 to 11, has reported to the government that concrete measures must be taken soon.

Bilateral discussions are expected to begin as early as September and construction may start next spring for completion in 2009, the sources said.

Currently, the core parts of retired submarines where the nuclear reactors are located are covered by concrete and moored at port after spent nuclear fuel is removed. Experts worry about radioactive leaks through corrosion.

The two countries will decide how to share the costs in upcoming negotiations. Japan has been supporting Russia in dismantling retired nuclear submarines in the Far East since 1993, but progress has been slow relative to northwestern Russia, where the effort receives aid from European countries.