First contact made with melted nuclear fuel at Fukushima plant

Re:First contact made with melted nuclear fuel at Fukushima ... by pvaldes on Friday February 15, 2019 @08:28PM (#19176395)

You are missing there an important factor: Life and dynamics of marine ecosystems. One of the problems is that 137Cs is being accumulated by sea currents, therefore even if we have a safe level in eight years, we could have, lets say, the "double" of the safe level in 16 years, rising to "four" times in the next 30 years (of expected half life of 137Cs). Minus the Cs released again to the water, but...

The other potentially big problem is that Caesium is bioaccumulative. Clams and other animals could take it from the water again.

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Re:First contact made with melted nuclear fuel at Fukushima ... by gus_massa on Friday February 15, 2019 @09:25PM (#19176620)

Good points. Bioaccumulation is a real problem. For example from https://en.wikipedia.org/wiki/Caesium-137#Radioactive_caesiu...

> In Scandinavia, some reindeer and sheep exceeded the Norwegian legal limit (3000 Bq/kg) 26 years after Chernobyl.

About the slow accumulation in the sand: If we make some simplifications and assume that without decay the flow rate is constant and the concentration increase linearly and in 32 years the concentration will be 5x the current amount. But when we add the decay the actual concentration will be only 2.5x the current amount.

(With a simple model like this using 30 years for the half life, I get the peak in the year 2043 with a concentration 2.4x of the current value.)

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