237Np/129I atom ratios in the Arctic Ocean: Has 237Np from Western European and Russian fuel reprocessing facilities entered the Arctic Ocean?

Radioactive waste discharges from European nuclear fuel reprocessing facilities have introduced a suite of radionuclides (90Sr, 99Tc, 129I, 134Cs, and 137Cs) into the Arctic Ocean by advection of North Atlantic water through the Norwegian Sea and Fram Strait. Measurements made in 1994 of 237Np ( year) and 129I (T1ı2=15•7×106 year) in surface waters (0–300 m) of the Arctic Ocean show a strong linear correlation in their concentrations below the Polar Mixed Layer (30–50 m) indicating that 237Np discharged from these same facilities (principally ellafield) has entered the Arctic Ocean. Budget calculations indicate that global fallout carried with runoff plus discharges from Russian reprocessing facilities have contributed 237Np to the upper Arctic Ocean in about equal proportions, but their combined total is less than half that from Sellafield. Fallout from the Chernobyl accident added insignificant amounts of 237Np and 129I to the Arctic Ocean compared to discharges from Sellafield and La Hague.