tokyo

The Japanese government may have to revise its disposal programme for radioactive waste, following a report from the Ministry of International Trade and Industry (MITI) pointing out the expense of building an underground repository for high-level nuclear waste.

The interim report, released last week by MITI's committee on atomic energy, claims the cost of underground disposal to be eight times more expensive than in France and 13 times more than in Britain. MITI attributes the high estimated cost to extra work required to overcome the problem of high groundwater levels in Japan.

The cost of deep underground disposal in Japan is estimated to be ¥2.7 million (US$22,460) per cubic metre. According to the report, disposing of 15,000 tonnes of nuclear waste — an average amount produced from dismantling a light-water reactor — could cost ¥19.2 billion.

Given the geological constraints, the construction of the repository would require detailed planning. This would include protective measures against earthquakes to minimize the risk of radioactive material leaching into groundwater.

With a nuclear waste reprocessing facility currently under construction in Rokkasho village, Aomori Prefecture, the government is planning to dispose of nuclear waste in a deep underground repository which it hopes to build between 2030 and 2040 (see Nature 379, 478; 1996).

Japan Nuclear Fuel Cycle Development Organization (JNC), formerly the Power Nuclear Fuel Development Corporation, which plays a central role in investigating the feasibility of deep disposal, is expected to prepare a progress report on nuclear waste disposal by the end of this year.

Based on this report, the government will evaluate the technological reliability of deep disposal by next year, when it plans to establish an agency to carry out the project.

JNC is investigating the ‘multi-barrier’ system, consisting of engineered barriers (such as vitrified waste and buffer material) and the natural barrier provided by geological formations, as the main model for the planned repository.

But the location of the underground facility remains undecided. And the expense of the programme is likely to become an additional problem, particularly with large cost overruns and delays in the construction of the reprocessing facility.

While MITI is exploring the possibility of extending the operating period of existing nuclear reactors, JNC is planning a more economical model for the repository, for example by relaxing some of the regulations governing its construction.

Meanwhile, the Atomic Energy Commission, which advises the prime minister, has set up a committee to study ways of reducing the production of high-level nuclear waste.

Three research institutes, including JNC and Japan Atomic Energy Research Institute (JAERI), are developing a technology to stabilize high-level radioactive waste by using fast-breeder reactors and high-energy accelerators.

According to JAERI, such technology could reduce the production of high-level waste by up to 30 per cent, opening up the possibility of keeping such waste “above the ground”.