There is still some ongoing fission!!!
The sludge was collected in the Northern part of Fukushima prefecture.
Their data shows I-131 started being detected on 6/12/2014. It kept being detectable since then and it reached the peak on 6/14/2014. The reading was 1,017.2 Bq/Kg.
It was still 800 Bq/kg the next day.
I-131 density went in the decreasing trend after the peak, but it kept on being detected until the end of June. The data of July hasn’t been published.
I-131 can be detected when it’s used for medical treatment, and also nuclear fission occurred in Fukushima nuclear plant.
It could have been from the medical usage, however it can be unlikely to have increased gradually.
Cs-134/137 has been continuously detected from the beginning of this year.
Tepco has made no announcement about this I-131 measurement.