TRANSFER, PATHWAYS, ENRICHMENT, AND DISCHARGE OF CS-137 AND SR-90 IN THE PULP INDUSTRY

Natural and artificial radionuclides are transferred from terrestrial ecosystems via the forest industry to coastal sea water. The material processed, i.e., wood, fresh water, and bark, have low levels of radio nuclides, but large amounts of raw materials are processed annually. T hus the annual flux of radionuclides is substantial. The purpose of th is investigation was to study transfer, redistribution, enrichment, an d discharges of Cs-137 and Sr-90 in pulp industry employing the sulpha te process, Cs-137 and Sr-90 were measured by means of Ge-detectors an d a low level liquid scintillation spectrometer, respectively. Cs-137 was highly enriched in the recovering process for sodium, while Sr-90 was enriched in the recovering system for calcium compared to concentr ation levels in raw materials. The concentrations of Cs-137 and Sr-90 in bark were almost ten times the concentration level in conifer wood. No Cs-137 or Sr-90 could be identified in atmospheric discharges from the combustion processes. The products contained very low levels of t hese radionuclides. Only 5% of the annual input of Cs-137 and Sr-90 we re found in the products. Discharges of radionuclides from this partic ular pulp production plant is nearly 40% of the annual Cs-137 and Sr-9 0 input. The contribution of Cs-137 and Sr-90 to coastal seawater is p robably of minor importance providing that wood or fresh water from hi ghly contaminated areas are not utilized.