While the amount of tritium released from Fukushima I Nuclear Power Plant since May 2011, 20 to 40 trillion becquerels which TEPCO finally told Nuclear Regulatory Authority on August 2, 2013, could be an order of magnitude lower than the amount if April 2011 were included, it would pale in comparison to what Rokkasho Reprocessing Plant in Aomori Prefecture would be releasing if (big IF) it ever becomes operational (the October 2013 target has been moved yet again).
According to Wikipedia on Rokkasho Reprocessing Plant (in Japanese):
Amount of tritium to be released to the Pacific Ocean in liquid:
- 18,000 trillion becquerels (terabequerels) per year
Amount of tritium to be released into the atmosphere:
- 1,900 trillion becquerels (terabequerels) per year
Bioconcentration of tritium is supposed to be non-existent. But my search found this paper titled "Bioaccumulation of tritiated water in phytoplankton and trophic transfer of organically bound tritium to the blue mussel, Mytilus edulis." Jaeschke BC, Bradshaw C (Department of Systems Ecology, Stockholm University, SE-106 91 Stockholm, Sweden), Journal of Environmental Radioactivity, January 2013.
18,000 trillion becquerels per year into the ocean which has 829,000 trillion becquerels of tritium (according to UNSCEAR 2000 report quoted by TEPCO). Rokkasho would be adding over 2% of the existing amount to the ocean every single year. That's rather big for comfort.