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Reduced levels of technetium-99 and caesium-137 in seawater


4.1 Pollution will not cause injury to health or environmental damage.


Levels of selected radioactive substances in the environment
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Are we moving in the right direction? Published by Norwegian Radiation Protection Authority

The technetium-99 level in seawater outside the coast of Norway has decreased since 1999 and now displays a stabile decline. The decline is related to the reduced releases of technetium-99 from Sellafield since 1995–1996. It takes three to four years for the Sellafield releases to reach Norwegian waters and for the effects to become appearent. In 2004, the removal of technetium-99 was further enhanced. The concentration of technetium-99 in seawater along the Norwegian coast is therefore expected to be further reduced in the years to come.

The level of caesium-137 in the seawater outside the coast of Northern Norway has been relatively stable in recent years. The annual releases of caesium-137 from Sellafield has remained at the same low levels during the last decade. Caesium-137 from the Chernobyl accident and atmospheric nuclear testing in seawater is also reduced due to physical decay. Some of the caesium-137 present in the sea may also attach to particles and settle on the sea floor.