Toxic radioactive substances in groundwater at the crippled Fukushima nuclear plant have rocketed over the past three days, its Japanese operator said on Tuesday, admitting it did not know where the leak was coming from.
Samples taken on Monday showed levels of possibly cancer-causing caesium-134 were more than 90 times higher than they were on Friday, at 9 000 becquerels per litre, Tokyo Electric Power (Tepco) revealed.
Levels of caesium-137 stood at 18 000 becquerels per litre, 86 times higher than at the end of last week, the utility said.
“We still don’t know why the level of radiation surged, but we are continuing efforts to avert further expansion of contamination,” a Tepco spokesperson stated.
Government guidelines permit caesium-134 and -137 at 60 becquerels per litre and 90 becquerels per litre respectively.
Once ingested, the substances accumulate in muscle and bone and are believed to cause cancers.
Groundwater
The new readings came two days after Tepco said tritium, a radioactive isotope of hydrogen used in glow-in-the-dark watches, was present at levels 10 times the permitted rate.