Supply of medical isotope secured


The Japan Atomic Energy Agency has developed technology for the efficient production of molybdenum-99 (Mo-99), paving the way for Japan to end its total dependence on imports for the radioisotope indispensable for nuclear medicine.

Mo-99 is used to produce technetium, a radioactive tracing agent, for the diagnostic imaging of diseases such as cancer, disorders in cerebral blood flows and cardiac infarction.

Japan is the world’s second-largest user of Mo-99 after the United States, but the need for domestic production is strong as imports have been completely halted, on a temporary basis, in the recent past.

Between 2009 and 2010, nuclear reactors in Canada and the Netherlands, which together account for more than 50 percent of the world’s supply of Mo-99, were unable to produce the radioisotope due to accidents.

In addition, it is impossible to stockpile large amounts of Mo-99 because its half-life is as short as 66 hours.

Following the reactor accidents, the Japan Radioisotope Association, which provides radioisotopes for nuclear medicine in Japan, asked hospitals and other organizations concerned to delay the diagnostic imaging of diseases and use alternative materials, according to Yoshihide Nakamura, a senior official with the association.

Worldwide, most reactors that produce Mo-99 were built around 50 years ago. With the Canadian and Dutch reactors expected to stop operating in 16 to 18 years, Nakamura said, “There may be another supply crisis then.”

The agency thus launched a project, commissioned by the Ministry of Education, Culture, Sports, Science and Technology, to develop a method to produce Mo-99. Using a new method called “plasma sintering,” it has succeeded in producing a pellet of high-density molybdic anhydride in a short period of time.

The pellet efficiently produces Mo-99 when neutrons are applied to it in a special reactor, according to agency officials.

While Mo-99 is usually produced through the fission of highly enriched uranium in a reactor, the agency had to develop a different method because such uranium can be used for nuclear weapons and is subject to strict regulation under the nuclear nonproliferation regime.

The newly developed technology is expected to produce enough Mo-99 to meet 20 to 25 percent of domestic demand. The agency hopes to make it commercially viable by fiscal 2015.

The agency now needs to conduct demonstration tests for the technology at the Japan Materials Testing Reactor of its research and development center in Oarai, Ibaraki Prefecture. But the JMTS is currently idled and its restart is not in sight due to the Fukushima No. 1 nuclear plant crisis.

The government should approve the restart of the JMTS “as soon as possible to get (the project) rolling,” said an agency official.