Tokyo Electric, operator of the Fukushima Daiichi nuclear power plant, is hoping to draw groundwater and release it into the Pacific Ocean before it becomes highly contaminated while passing through the facility.
On Monday, a TEPCO official speaking at a meeting with fishermen in Iwaki City said the utility tested samples from the 12 wells dug to pump up the groundwater.
According to TEPCO, one of the wells contained radioactive materials in excess of the target level for release, but three days later a sample from the same well was measured below the target level.
The utility does not have any clues as to why the radiation levels are varying so much.
The fishermen were concerned by the update and asked TEPCO to carefully monitor radiation levels in the water and also determine the reason why radioactivity above target levels were identified.
Tsunemasa Niitsuma, a senior TEPCO executive, said that TEPCO will come up with a contingency plan in case radiation levels in the groundwater pumped up exceed the target levels.