100 Stories1978 The Enriched Uranium Technology That Uses Ion-Exchange Membrane, Drawing Global Attention

A research project on nuclear power was once conducted as part of Japan’s basic policy, energy security. That is the enriched uranium research and development project that was conducted in the Kawasaki Plant.

As nuclear power, especially nuclear power generation, continued to become more important as an energy source that replaces petroleum, the nuclear fuel enriched uranium was all supplied from outside Japan at the time.

The enriched uranium used as fuel for nuclear power generation is a three-percent concentrate of uranium-235, which is found in naturally produced uranium. Natural uranium only contains 0.7 percent of uranium-235 and the rest of it is made up of incombustible uranium-238.

Around 1980, the gaseous diffusion method was used as the only method for implementing the uranium enrichment technology. However, the development of new technology was awaited because this method required large amounts of electricity.

Many countries, including Japan, were working on developing the centrifugal separation method, which uses less than a tenth of the electricity compared to the gaseous diffusion method. However, the problem with this method was in reducing the cost of each centrifuge because it required each plant to have tens of thousands—or even hundreds of thousands—of centrifuges.

On the other hand, Asahi Kasei was researching and developing something called the chemical method. In comparison to the gaseous diffusion method and the centrifugal separation method, this was a low-cost, low-energy method. It is also easy to produce large capacities, operate, and maintain due to the simplicity of the process. Moreover, it is a dream technology that has the feature of being a peaceful-use enrichment technology, which cannot produce the highly enriched uranium used in nuclear weapons.

Despite having so many advantages, it was said to be impossible to apply even though it should work in theory. This is because the chemical method uses the difference between the properties of uranium-235 and uranium-238, and this difference is very slight. The United States Atomic Energy Commission’s report (also known as the Benedict Report) gave a strict evaluation, stating that it would take centuries to apply this method.

However, Asahi Kasei’s engineering staff continued their tenacious research based on various technologies they have accumulated over many years. As a result, they succeeded in developing a method that efficiently utilized this slight difference in chemical properties. By utilizing our company’s technology, the ion-exchange membrane, it instantly became feasible for practical application.

The Japan Atomic Industrial Forum published a report on this research, stating that it “has great potential.” The government took up this project as a subsidized project and paid two thirds of the research funds.

After receiving support from the government, new research facilities were established in Hyuga City from the existing Kawasaki Plant to expand the research scale. Asahi Kasei continued its research on the uranium enrichment technology that uses its original chemical method and succeeded in extracting three-percent enriched uranium.

However, the uranium enrichment research institute in Hyuga City was suspended in 1991 because the government’s subsidy ended. The reason is that “the purpose of the research was achieved and that the international demand and supply for enriched uranium is expected to decline.”

The development of enriched uranium technology was a big project where the total investment amount was 27 billion yen and the government’s subsidy was 12 billion yen. At first, research on nuclear power generation was required in order to find alternative energy that replaces petroleum because of the social problems it creates due to the photochemical smog produced from thermal power stations and the oil crisis.

The research on nuclear power generation has ended, but the challenges of ion-exchange membrane continue. It is currently applied in fuel cell membranes to store electricity rather than generate power.