Each year the Japanese government releases data on the previous year's plutonium inventory. Figures showing the status of the inventory at the end of the 2004 calendar year have now been released (see table 1).

As can be seen, Japan's plutonium inventory continues to grow and projections (see table 2) made by the Institute for Science and International Security (ISIS) show that Japan is likely to maintain significant inventories of surplus plutonium well into the future (Global Stocks of Nuclear Explosive Materials, Chapter IV, "Separated Civil Plutonium Inventories: Current Status and Future Directions", by David Albright and Kimberly Kramer, June 10, 2005, Revised July 8, 2005). ISIS's projections relate to the following five cases::

Case 1 (optimistic, full operation of Rokkasho): First 2 reactors loaded with MOX in 2008, 2 more in 2009, 8 loaded by 2010, 18 by 2012 including Ohma, Monju starts in 2008, maximum plutonium loaded each year is about 9 tonnes.

Case 2: 2 year delay on Case 1 loading schedule, otherwise the same.

Case 3: 4 year delay on Case 1 loading schedule, otherwise the same.

Case 4: Based on Case 1, but the plutonium stored in Europe (estimated to be almost 50 tonnes after all overseas reprocessing contracts completed) is used first. Due to the licensing limit of 30 tonnes on unirradiated plutonium that can be stored at Rokkasho¹, reprocessing at Rokkasho is limited to 2 tonnes per year for about 7 years. Need 60-100 tonnes per year of MOX fuel to be fabricated from plutonium stored in Europe (fabricated in Europe or in Japan).

Case 5: No MOX used, but Rokkasho separates plutonium until the 30 tonne storage limit reached.

Plutonium inventory estimates for Cases 1, 2 & 3 remain relatively high because supply and demand are about equal after 2010 (about 7 tonnes per year separated and 7-9 tonnes loaded into reactors)

ISIS's projections are based on various assumptions. At this point in time it is impossible to speak with any certainty about Japan's future reprocessing and plutonium use programs, but CNIC believes that ISIS's projections represent a plausible range of possible outcomes.

1. Presumably this refers to the 60-tonne limit specified in the license application for uranium and plutonium mixed oxide. Since this is mixed 50-50, it represents a 30-tonne limit for plutonium.

Table 1

Table 2

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