BBC News Asia
1 September 2013 Last updated at 09:09 GMT
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 plant was crippled by the 2011 earthquake and tsunami.
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 recording, using a more sensitive device, showed a level of 1,800 millisieverts an hour.
The new reading will have direct implications for radiation doses received by workers who spent several days trying to stop the leak last week, the BBC’s Rupert Wingfield-Hayes reports from Tokyo.
In addition, Tepco says it has discovered a leak on another pipe emitting radiation levels of 230 millisieverts an hour.
The plant has seen a series of water leaks and power failures.
The 2011 tsunami knocked out cooling systems to the reactors, three of which melted down.
The damage from the tsunami has necessitated the constant pumping of water to cool the reactors.
This is believed to be the fourth major leak from storage tanks at Fukushima since 2011 and the worst so far in terms of volume.
After the latest leak, Japan’s nuclear-energy watchdog raised the incident level from one to three on the international scale measuring the severity of atomic accidents, which has a maximum of seven.
Experts have said the scale of water leakage may be worse than officials have admitted.
The use of detectors of the appropriate range and type for the radiation being measured is Radiac defence 101.
I wonder at the depth and complexity of the propaganda campaign being waged by nuclear industry. They have the data and the timeline, so its a matter of guess work.
In the end the industry will stand up and trumpet its greatness no doubt, and the death of TEPCO by a thousand cuts is part of it. The old is dead, the new wears a mask that is not, really, new at all.
Admission of a lie does not herald a new era of openness and public trust. It just means gradualism, and consistent striving to the same old ends.
When a geiger muller instrument is used in radiation fields above its ability to read, the instrument will suffer drenching and read zero for a time, before recovering. After this recovery time, if the field remains above the instrument’s ability to read, the machine will again drench and give a false zero. So one wonders who was employed to do the readings for any operator trained in use of the detector would know a force zero when it occurs in a known radiation field.
In short, by 100 mSv, they must have known the reading was more than 100 mSv by the behaviour of the instrument.
A background detector is too sensitive to read lethal and other high level fields.