Fuel Amounts at Fukushima

March 17, 2011
David Wright

NOTE: On March 21, an updated set of numbers was posted here.

Based on Japanese press stories, we have compiled a table of the amount of fuel in the cores of the reactors and the spent-fuel pools in the 6 reactors at the Fukushima Dai-Ichi nuclear facility.

While BWR fuel comes in various sizes, the last column assumes 170 kg per assembly. Each fuel assembly consists of roughly 60 fuel rods.

Thanks to readers for confirming that the fuel rods in Unit 4 had been moved from the core to the spent fuel pool during maintenance.

Units 5 and 6 were reported to be producing power in January, but are now shut down for mainenance. Reports say that 130 assemblies from each core were recently transfered to the pools, but those were included in the previous numbers in the table for the spent fuel for those reactors. If anyone has additional information about these reactors, please let us know.

A New York Times article states that 32 assemblies in the spent fuel pool of Unit 3 are MOX. The MOX fuel rods were stored in the pool but TEPCO announced they were being loaded into the core last fall, so we think those are currently in the core.

The same article says that a total of 11,125 spent fuel assemblies are stored at the Fukushima Dai-Ichi facility. However, not all of those are stored in the pools in the reactor buildings. Several hundred are currently in dry cask storage, and more than half of the total are stored in a common storage pool.

Thanks to Masa Takubo for his help in compiling these numbers.