Fukushima nuclear plant seismometers were broken, says operator

The operator of the wrecked Fukushima nuclear power plant said on Monday (Feb 22) that two seismometers at one of its three melted reactors have already been out of order since last year and did not gather data whenever a powerful earthquake struck the area earlier this month.

The acknowledgement raised new questions about whether the company's risk control has improved since a massive earthquake and tsunami in 2011 destroyed a lot of the plant.

The malfunctioning seismometers surfaced during a Nuclear Regulation Authority meeting on Mon to discuss new damage at the plant caused by a magnitude 7.3 quake that struck the spot about Feb 13. Cooling water and pressure levels fell in the machine 1 and 3 reactors, indicating additional harm to their key containment chambers.

The operator, Tokyo ENERGY Co, has repeatedly been criticised for cover-ups and delayed disclosures of problems at the plant.

Regulatory officials asked TEPCO in the meeting why it again did not have seismological info from the Unit 3 reactor for Saturday's quake, and utility officials acknowledged that both of its seismometers had failed - 1 in July and the other found in October - and had never been repaired.

TEPCO also said that seismometers in all but two of the reactor properties that survived the 2011 disaster were submerged by normal water from the tsunami and also have never been replaced.

During Monday's meeting, regulatory officials said these were worried about the declining normal water amounts and pressure in the machine 1 and 3 major containment chambers as a result of the opportunity that the quake experienced expanded the existing destruction or opened new leakage paths, and urged the utility to closely check for any improved radiation levels in the bottom drinking water surrounding the reactor properties.

TEPCO said zero abnormality has been detected found in water samples up to now.

New damage could even more complicate the plant's already tough decommissioning process and enhance the large amounts of contaminated water being placed at the plant.

Since the 2011 disaster, cooling water has been escaping constantly from the damaged primary containment vessels in to the basements of reactor and turbine buildings, where the volume increases as groundwater seeps in. The normal water is definitely pumped up and cared for, then part of it is reused as cooling water, as the rest is kept in about 1,000 tanks.

TEPCO initially reported there is no abnormality in the plant from Saturday's earthquake. But on Mon, it said about 20 of the tanks had slid slightly as a result of quake, a storage space container carrying radioactive waste materials had tilted, and asphalt pavement at the plant was cracked.