A simple and reliable monitoring system for 3H and 14C in radioactive airborne effluent

Diverse Monitoring Approaches Reveal 14C Dispersion Pattern and Its Impact on the Environment around the Tokai Reprocessing Plant

“…The results consistently gave the picture of a 14 C dispersion pattern brought about by the prevailing wind in this area, which conveys the 14 C plume, and as a result, caused elevated 14 C concentrations in the area 2-3 km southwest of the main stack of the TRP. The increases in 14 C concentration were, however, quite temporary, and the baseline concentration remained at the background level even in the elevated area. The 14 C concentrations in vegetations generally followed those in atmospheric CO 2 , but seemed different in 14 C uptake response between vegetation types, emphasizing the importance of this nature not only in its application as bioindicators in environmental monitoring but also in establishing a more realistic dose evaluation model for 14 C. Through a series of investigations, we found the highest 14 C concentrations of…”

“…4) Carbon-14 has also been artificially produced by the nuclear industry in nonnegligible amounts recently, and accordingly, part of this artificially produced 14 C has been released into the atmosphere by nuclear power plants and by spent fuel reprocessing plants. 5) Carbon-14 is a particularly interesting radionuclide from the perspective of dose estimation due to the nuclear industry because of the role of carbon in the metabolism of all life forms.…”

“…12) Some of the 14 C atoms formed in the coolant are released into the atmosphere during normal operations of the reactors at the power plant sites, whereas 14 C produced in the fuel is released at fuel reprocessing plant sites when the fuel is reprocessed. Thus, a fuel reprocessing plant serves as an important potential source for atmospheric 14 C release from the nuclear fuel cycle.…”

“…Based on the comprehensive observation and a simple model calculation with data on 14 C release and meteorology, we attempt to establish the dispersion pattern of 14 C released from the TRP. Additionally, we compare 14 C concentrations in vegetations with each other and with those in atmospheric CO 2 to discuss how vegetations reflect the environmental 14 C level around the atmospheric 14 C source. Finally, we estimate the maximum annual effective dose delivered from 14 C due to the operations of the TRP, and consequently lead to the conclusion that the 14 C releases have a very slight impact on the public.…”

“…We collected atmospheric CO 2 , rice grain, leafy vegetable, and Japanese mugwort samples at various locations at different time intervals, and measured their 14 C concentrations to show the spatiotemporal distribution of 14 C around the Tokai reprocessing plant (TRP). The results consistently gave the picture of a 14 C dispersion pattern brought about by the prevailing wind in this area, which conveys the 14 C plume, and as a result, caused elevated 14 C concentrations in the area 2-3 km southwest of the main stack of the TRP.…”