Photo/IllutrationThe upper part of the reactor vessel of the Monju prototype fast-breeder reactor in Tsuruga, Fukui Prefecture (Asahi Shimbun file photo)

France has decided to sharply scale down its ASTRID fast-reactor project, which is supported by Japan.

France’s decision underscores afresh the dismal outlook of Japan’s plan to continue the development of fast-reactor technology by relying on an overseas project.

Now that it has become unclear whether participation in the ASTRID project will pay off in future benefits that justify the huge investment required, Japan should pull out of the French undertaking.

Fast reactors are a special type of nuclear reactors that burn plutonium as fuel. The ASTRID is a demonstration reactor, the stage in reactor technology development just before practical use.

The French government has said the Advanced Sodium Technological Reactor for Industrial Demonstration, if it comes on stream, will generate 100 to 200 megawatts of electricity instead of 600 megawatts as originally planned. Paris will decide in 2024 whether the reactor will actually be built.

Japan has been seeking to establish a nuclear fuel recycling system, in which spent nuclear fuel from reactors will be reprocessed to extract plutonium, which will then be burned mainly in fast reactors.

When the Japanese government in 2016 pulled the plug on the troubled Monju prototype fast-breeder reactor, which was at the technology stage prior to that of a demonstration reactor, it decided to make the joint development of the ASTRID the centerpiece of its plan to continue the nuclear fuel recycling program.

The government will provide some 5 billion yen ($45.2 million) annually for the French project through the next fiscal year, which starts in April, and decide, by the end of this year, whether and how it will be involved in the project after that.

Because of significant differences in the roles of prototype and demonstration reactors, a simple comparison between the Monju and the ASTRID can be misleading.

But it is clearly doubtful whether the ASTRID, which will be smaller than the Monju, will offer sufficient benefits for Japan’s fuel recycling program.

If it fully commits itself to the joint development of the ASTRID in response to France’s request, Japan will have to shoulder half the construction cost, estimated to be hundreds of billions to 1 trillion yen, and assign many engineers to the project. But these resources could end up being wasted.

Over the years, the government spent more than 1.1 trillion yen of taxpayer money on the Monju, designed to be a small-scale example of the potential of the fast-breeder reactor technology. But the prototype reactor remained out of operation for most of the two decades after it became operational. It actually accomplished only a small fraction of what it was designed to achieve.

The government should make an early decision to end its involvement in the ASTRID to avoid repeating the mistake it made with the Monju project, which was kept alive at massive cost for far too long as the decision to terminate it was delayed for years without good reason.

The government has only itself to blame for the current situation. Despite deciding to decommission the Monju, it stuck to the old fuel cycle policy without conducting an effective postmortem on the Monju debacle. Instead, the government too readily embraced the ASTRID project as a stopgap to keep its fast-reactor dream alive.

The government needs to rigorously assess whether it is wise to continue developing fast-reactor technology.

Producing electricity with a fast reactor is costlier than power generation with a conventional reactor that uses uranium as fuel. The United States, Britain and Germany phased out their own fast-reactor projects long ago.

France has continued developing the technology, but feels no urgent need to achieve the goal. The country predicts that the technology will be put to practical use around 2080 if it ever is.

Even if Japan wants to continue developing fast-reactor technology, it would be extremely difficult to build a demonstration reactor for the project within the country given that even finding a site to build an ordinary reactor is now virtually impossible.

The government would be utterly irresponsible if it aimlessly keeps pouring huge amounts of money into the project when there is no realistic possibility of the technology reaching the stage of practical application.

If it abandons the plan to develop fast-reactor technology, the government will have to rethink the entire nuclear fuel recycling program.

Any such fundamental change of the nuclear power policy would have serious implications. But there is no justification for postponing the decision any further.

--The Asahi Shimbun, June 17