Behaviour and radiological significance of tritium from nuclear power plants and other sources in the rhine river basin

• Published in: Journal of environmental radioactivity 1991, Vol.14 (4), p.341-360
• Main Authors: Mundschenk, H., Krause, W.J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Continental surface waters; Exact sciences and technology; Natural water pollution; Pollution; Water treatment and pollution
• ISSN: 0265-931X; 1879-1700
• DOI: 10.1016/0265-931X(91)90024-A

Since 1976, Swiss and German nuclear power stations and a fuel reprocessing plant have released 180±45 TBq (±one standard deviation) of tritium yearly in waste water to the Rhine and its tributaries. Although these annual releases were rather uniform throughout this period, tritium concentrations in the rivers decreased exponentially, with rate constants up to 0·15 y −1. The amount of tritium flowing out of the catchment area upstream of Bockum decreased from 1500 TBq in 1978 to about 460 TBq in 1989. The fraction contributed by known industrial releases increased from 0·1–0·2 to 0·2–0·4 over this time. Radioactive decay and removal of bomb tritium to the oceans also reduced the input of tritium to this catchment by precipitation from 2000 TBq in 1978 to 380 TBq in 1989. The tritium outflow of the Rhine was higher than could be accounted for by precipitation input and known industrial releases. The difference is most probably due to the slow release of more highly tritiated groundwater, recharged during earlier years of the post-bomb era, but may also include some untraced industrial releases. Radiation dose contributions due to drinking water extracted from the Rhine were less than 0·1 μSv y −1, quite negligible compared to the legally adopted dose limit of 300 μSv y −1 and to the mean natural radiation exposure of 2000 μSv y −1 in Germany.