Radiological examination of Sogna. Revised edition of IFE/KR/E--2002/005

This is a revised edition of IFE/KR/E-2002/005. The reason for the revision is that the former point of emission into Sogna is marked off somewhat erroneously on the map in that report. After the publication of that report some further measurements of natural uranium have been done; they are given in the present report. The background for the present work was public concern about previous emissions of radioactive material from research activities at Institute for Atomic Energy, IFA, at Kjeller, Norway (now IFE). In february 2001, sediment samples were collected from eight locations in Sogna, which was a branch of the river Nitelva. One sample was taken at the outlet of the sewage pipe from which the low-level radioactive waste was emitted. Representatives from the The Norwegian Radiation Protection Authority (NRPA) were present to ensure independent results and they took their own samples for control measurements. This report gives the results obtained by IFE. The report also deals with the emissions to Sogna and earlier radiation measurements. All samples were measured with respect to gamma emitting nuclides. Selected samples were analyzed for 90Sr and 239/240Pu and natural uranium. All measured concentrations of activity are below the limits set by NRPA for the excavation of the contaminated areas of Nitelva and the buried barrels from IFE's depository. Elevated concentrations of natural uranium were measured in the sample from the outlet of the pipe, probably arising from a documented emission of the Swedish part of the uranium purification plant (the Silex plant) in 1963. Except for the very first years from 1954-57, routine control was made of the levels of activity in Sogna and Nitelva for all the years in which there was emission to Sogna. No activity concentrations have ever been found that can be expected to have any negative health effects. It is thus very unlikely that there is or ever has been any health risk to staying in the area because of contamination with radioactive substances from IFE