Lifecycle of palladium in Japan: for setting clearance levels of 107Pd

ABSTRACTResearch on the recycling of useful elements in spent nuclear fuels of light-water cooling reactors is progressing. Palladium (Pd), a fission product in high-level radioactive waste, is one of the elements that can be recovered and recycled. Even if the Pd recycling system is successfully established, 107Pd contamination will be unavoidable. In this report, we review the lifecycle of Pd (applications, environmental levels, and human exposure) with respect to setting clearance levels for 107Pd. The major applications of Pd in Japan are catalysts for automobile exhausts and chemical industries, followed by dental prostheses and electrical devices. The World Health Organization reported a daily uptake of Pd from drinking water and food of 0.03 and <2 μg person−1, respectively. The uptake of a person with a dental prosthesis containing Pd might reach up to 15 μg day−1. The Pd uptake by the public via inhalation of particulate matter from automobile exhaust catalysts is not as large, even in urban area...