Stricken Fukushima No. 1 Nuclear Power Plant operator TEPCO recently admitted that incorrectly configured monitoring equipment at the plant meant the groundwater flowing beneath the plant from the nearby Abukuma mountains may have become contaminated since April.
In order to mitigate a longstanding groundwater problem — that some experts, including a prime minister’s advisor, claim existed since the 1970s — TEPCO sunk numerous wells. According to the utility incorrect gauge settings were used to measure groundwater levels in six of those wells, which are situated near reactors 1 through 4, all of which were which were destroyed by the 2011 nuclear disasters.
The water gauges had been installed with the specific aim of keeping groundwater levels in the wells a meter higher than the contaminated water in the buildings. However, the faulty monitoring equipment meant groundwater readings were about 70 cm lower than what TEPCO was measuring, meaning contaminated water had been leaking into the ground for almost 6 months.
Between May 17 and 21, groundwater reportedly fell as much as 20 cm below the safety levels at least eight times.