Workers at Fukushima Daiichi have encountered more contaminated water around the grounds of the damaged plant. Meanwhile, prosecutors this week declined to pursue criminal charges against Tokyo Electric Power Co. executives related to the deaths of hospital patients evacuated during the crisis.

Recent developments related to the TEPCO power plant severely damaged following Japan’s 2011 earthquake and tsunami include:

Above-ground tanks at Fukushima Daiichi. Source: TEPCOTank Leak Likely Reached Groundwater

An abrupt spike in tritium detected in a test well suggests that a leaking above-ground tank likely contaminated nearby groundwater. TEPCO reported that sampling Tuesday detected the radioactive hydrogen isotope at 64,000 becquerels per liter, compared to 29,000 becquerels per liter the previous day and 4,200 becquerels per liter on Sunday. About 300 metric tons of highly contaminated water is believed to have leaked from a nearby tank last month.

Ditch Leading to Sea Contaminated

On Wednesday, TEPCO workers detected various radioactive contaminants measured at 220 becquerels per liter in a ditch that drains to the sea. Kyodo News quoted TEPCO officials as saying they suspect the contamination came from water leaking through sandbags at another ditch undergoing decontamination.

No Criminal Prosecutions

Prosecutors declined to pursue criminal charges against TEPCO executives Monday. Citizen groups had lobbied for prosecution of former TEPCO Chairman Tsunehisa Katsumata, former Prime Minister Naoto Kan and about 40 others involved in the crisis. Charges would have centered on the deaths of fragile patients during evacuations from nearby hospitals, as well as radiation exposure among the population near the plant. Prosecutors concluded it would be too hard to prove criminal responsibility for inadequate natural disaster preparation at the plant, the Asahi Shimbun reported, because experts had not expected such a powerful earthquake and tsunami.