Japanese nuclear experts fear the vessel and its containers are not up to international standards.

Russia has been using a Soviet-era ship to transport spent nuclear fuel near Hokkaido and through the Sea of Japan, raising concerns about possible radioactive contamination in northern Japan, nuclear industry officials said.

Despite the risks of moving such highly radioactive material, Moscow is under no legal obligation to inform Tokyo of such shipments, Japanese government officials say.

But Russian authorities provided a map of the ship's route to the Japan Atomic Industrial Forum (JAIF) in autumn 2003. Until now, the route of the Russian vessel was not known.

The spent fuel is taken from dismantled nuclear-powered submarines at a plant in a suburb of Petropavlovsk Kamchatskiy on the Kamchatka Peninsula. The fuel is then loaded on a ship which passes through the Soya Strait, the narrow strip of water that separates Hokkaido and Russia's Sakhalin, according to JAIF officials.

The ship crosses the Sea of Japan and docks in Vladivostok to keep the fuel at a nearby temporary storage facility. From there, the fuel is carried by train to reprocessing plants.

``We have been informed by the Russian side that they transport spent nuclear fuel in containers placed in the vessel's storage area,'' said a Foreign Ministry official in charge of the issue. ``But we have not been told of the detailed transportation methods, the routes taken or the frequency of the transportation.''

The lack of information from Russia has added to Japanese fears about the spent nuclear fuel being transported so close to Japan.

A researcher at the Nuclear Safety Institute at the Russian Academy of Sciences said Moscow currently has no other route to get the spent nuclear fuel to the railway network. But even Russian scientists are concerned about possible hazards of transporting such a dangerous cargo by sea, the Russian researcher said.

Russian nuclear-powered submarines usually carry uranium fuel enriched by 20 percent or more. Some levels reach as high as 90 percent, about the same as for weapons-grade fuel, experts say.

In comparison, the level of enrichment of fuel used at Japanese nuclear reactors is about 3 percent.

There is also the issue of volume. Spent nuclear fuel from a single decommissioned submarine fills about a dozen 40-ton containers, according to nuclear industry sources.

Spent nuclear fuel from reactors in Japan is transported in double-hull cargo ships and special containers that meet international standards. But about the only detail known about the Russian vessel is that it was built in the mid-1980s.

``The containers are heavy, and I believe that the Russian ship would not withstand the weight if it carries many of them,'' said Kunihiko Uematsu, an adviser to JAIF and former vice president of what is now the Japan Nuclear Cycle Development Institute. ``There is also the possibility that the containers do not meet international standards.''(IHT/Asahi: January 11,2005)