Uh... They put the sediment sample in a plastic bottle?
According to TEPCO, the plastic bottle is emitting 4 millisieverts/hour radiation with the sediment in it.
From TEPCO's Photos and Videos Library, 2/22/2013:
Workers in full gear collecting samples through the hole on the first floor of the Reactor 1 building, where the air radiation dose ranges from 2 to 10 millisieverts/hour. It took 20 workers 2 hours and 35 minutes to complete the task, for which they received 1.46 millisievert (maximum) of radiation exposure.