Tokyo Electric Power Company has detected high radiation levels at two areas on the Fukushima Daiichi site, near the main exhaust stack for units 1&2 and inside the unit 1 turbine building.
On 31 July, TEPCO said that it detected a very high radiation sources at the Standby Gas Treatment System (SGTS) for units 1 and 2, when carrying out a radiation survery using a gamma camera after debris removal work in the area.
The following day, 1 August at 14:30, TEPCO measured a dose in excess of 10 Sv/hour coming from the exhaust stack of the SGTS. The SGTS system moves air from the reactor buildings to the environment through a series of filters, ultimately releasing it through the exhaust stack. TEPCO said that it had made the area off limits and would install shielding at a later date.
On 2 August, another high reading of 5 Sv/hour was measured on the 2nd floor of the unit 1 turbine building, near the entrance of the train room for the emergency gas treatment system.
Ralph Andersen an expert on radiation safety at the US Nuclear Energy Institute said that even higher radiation levels may be measured in areas of the site in future.
“As recovery efforts proceed, more extensive and detailed radiation surveys are being conducted. Given the severity of events at the site, it would not be surprising if even higher radiation levels were measured in some areas of the plant at a future time.”
FilesReactor-by-reactor Fukushima Daiichi restoration progress summary as of 8 August, from JAIF Fukushima Daiichi parameters as of 7 August by JANTI