27 Mars 2012
March 28, 2012
The lower-than-expected water level was discovered for the first time when the power utility used an industrial endoscope to check the crippled reactor's interior on Monday, TEPCO said.
According to some experts, it is possible that nuclear fuel that melted through the reactor's pressure vessel and accumulated on the bottom of the containment vessel in the aftermath of the March 11 earthquake and tsunami may not be completely covered in the water.
TEPCO said the water temperature in the vessel remained relatively low within a range of 48.5 C to 50 C. The discovery of the unexpectedly shallow water level will not affect TEPCO's judgment that the reactor is in a state of "cold shutdown."
March 27, 2012
TOKYO (Kyodo) -- The operator of the Fukushima Daiichi nuclear power plant on Monday found that the water level in the No. 2 reactor's primary containment vessel was only 60 centimeters deep when it checked the interior of the crippled reactor using an endoscope.
Tokyo Electric Power Co. spokesman Junichi Matsumoto gave assurances that the melted fuel inside the No. 2 reactor remains cooled through continuous water injection, as the water temperature in the vessel was 48.5 C to 50 C.
But he acknowledged that the lower-than-expected water level suggests that a large portion of the injected water is leaking from the primary containment vessel, possibly via the damaged suppression pool that is linked to the reactor.
To specify from where the water is leaking, the company needs a ''broader inspection,'' Matsumoto told a press conference. TEPCO plans to conduct another survey into the No. 2 reactor Tuesday to check the interior radiation level.
It is the first time the utility has confirmed the existence of water inside any of the Nos. 1 to 3 reactors since the nuclear accident was triggered by the huge earthquake and tsunami last March.
The fuel inside the Nos. 1 to 3 reactors is believed to have melted through the pressure vessels and accumulated in the outer primary containers.
The water filling the No. 2 reactor containment vessel was transparent, but some sediment was found. The sediment could be paint that peeled off or rust, and unlikely to be melted fuel, Matsumoto said.
As TEPCO could not confirm the water level in the previous industrial endoscope survey on Jan. 19, the company this time used a longer 20-meter endoscope to check deeper inside.
TEPCO also said Monday that about 120 tons of water containing radioactive substances leaked from the water circulation system involved in cooling the Nos. 1 to 3 reactors.
Of the leaked water, which is believed to contain radioactive strontium, 80 liters leaked out into the Pacific Ocean. The concentration level is about 140,000 becquerels per cubic centimeter, the company said.