Update: On January 18, 2013, the operational information included in the International Atomic Energy Agency's Power Reactor Information System database was reversed. The following day, the agency stated in a press release that the significant move was due to a "clerical error" by Japan's Nuclear Energy Safety Organization, which is the agency's counterpart in Japan.
In an unprecedented move, the International Atomic Energy Agency (IAEA) today retroactively re-categorized 47 Japanese nuclear reactors from "in operation" to "long-term shutdown" in its Power Reactor Information System. Thus, the global number of nuclear reactors listed as "in operation" drops from 437 to 390, a number not seen since Chernobyl-year 1986, when 391 operating units were on the list. Without a doubt, the step is a unique revision of world operational nuclear data -- not to mention a solid recognition of the industrial reality in Japan.
However, numerous questions remain. Though the agency officially defines its reactor-status categories, the actual specifics related to the handling of these categories remain unclear. Units can remain in the long-term shutdown category for many years, without any apparent limit. With today's change, Japan now has a total of 48 units listed under this category -- the Monju Nuclear Power Plant, a fast breeder reactor that has not been generating electricity since a sodium fire severely damaged the plant in 1995, was the only unit that the agency qualified for long-term shutdown before today's reshuffling.
Of the 47 Japanese units that the IAEA reclassified today for long-term shutdown, 42 reactors were entered retroactively as of January 1, 2012, (this strangely included the three units at the Kashiwazaki-Kariwa Nuclear Power Plant, which has not been generating power since an earthquake hit the site in 2007), while five reactors retroactively entered that listing between January 14 and March 26, 2012. One reactor, the Tomari-3 at the Tomari Nuclear Power Plant in Hokkaido -- the last unit to generate electricity before the country entered a two-month nuclear-free period between May 5 and July 5, 2012 -- remains, for unknown reasons, in both the "in operation" and "operational" categories. This is despite the fact that only two reactors are currently effectively generating power in Japan, units 3 and 4 at the Ohi Nuclear Power Plant in Fukui Prefecture.
The future of the Japanese nuclear power plants remains highly uncertain. In spite of a clearly more pro-nuclear government that came in with the 2012 election of Prime Minister Shinzo Abe, it will likely take years until more power plants could get back online. As Abe stated earlier this month:
"We will first of all determine whether or not to restart nuclear power plants on the basis of scientific safety standards. Then over the course of roughly three years we will assess the futures of existing nuclear power plants and transition to a new stable energy mix over ten years. The new construction or replacement of nuclear power plants is not a matter that is able to be determined immediately. Naturally this is an area in which we should make our determination in accordance with the principle of gradually decreasing our degree of reliance on nuclear power to the greatest extent possible."
Other sources have also suggested that it could take a long time for nuclear plants to adapt after the newly established Nuclear Regulatory Authority lays out its new safety standards in July 2013.
Editor's note: A version of this article was first published by the World Nuclear Industry Status Report. The author has two articles in the current issue of the Bulletin of the Atomic Scientists, a special issue titled: A French nuclear exit?