Radiation levels were being measured using devices with far-too-limited scales, the BBC reports:
Radiation levels around Japan’s Fukushima nuclear plant are 18 times higher than previously thought, Japanese authorities have warned.
Last week the plant’s operator reported radioactive water had leaked from a storage tank into the ground. It now says readings taken near the leaking tank on Saturday showed radiation was high enough to prove lethal within four hours of exposure.
The Tokyo Electric Power Company (Tepco) had originally said the radiation emitted by the leaking water was around 100 millisieverts an hour. However, the company said the equipment used to make that recording could only read measurements of up to 100 millisieverts.
The new reading will have direct implications for radiation doses received by workers who spent several days trying to stop the leak last week. Experts have said the scale of water leakage may be worse than officials have admitted.