TOKYO (AP) – The operator of the devastated nuclear power plant in Fukushima said on Monday that two seismometers at one of the three molten reactors had been out of order since last year and had not collected data when a powerful earthquake hit the area earlier this month.
The recognition has raised new questions about whether the company’s risk management has improved since a major earthquake and tsunami in 2011 destroyed much of the plant.
The dysfunctional seismometers surfaced during a meeting of the Nuclear Regulatory Authority on Monday to discuss new damage to the plant due to an earthquake with a magnitude of 7.3 that hit the region on 13 February. Cooling water and pressure levels dropped in units 1 and 3, indicating damage to their primary containment chambers.
The operator, Tokyo Electric Power Co., has been repeatedly criticized for covering up and delaying the disclosure of problems at the plant.
Regulators asked TEPCO at the meeting why there is no seismological data from the Unit 3 reactor for Saturday’s quake, and utilities acknowledged that both seismometers had failed – one in July and the other in October – and were never recovered.
TEPCO also said seismometers nearly two of the reactor buildings that survived the disaster in 2011 were flooded by the tsunami and were never replaced.
Regulators said at Monday’s meeting that they were concerned about falling water levels and pressure in Unit 1 and 3 primary containment chambers, due to the possibility that the earthquake had extended the existing damage or opened new leaks, and urged the municipality to carefully check for increased radiation levels in the groundwater around the reactor buildings.
TEPCO said that so far no abnormality has been detected in water samples.
New damage could further complicate the already difficult dismantling process of the plant and contribute to the large amounts of polluted water stored in the factory.
Since the disaster in 2011, cooling water has been continuously escaping from the damaged primary barrels in the basements of reactor and turbine buildings, where the volume increases as groundwater seeps in. The water is pumped and treated, and some of it is used again as cooling water, while the rest is stored in about 1,000 tanks.
TEPCO initially reported there was no abnormality at the plant since Saturday’s earthquake. But Monday said about 20 of the tanks slipped slightly due to the earthquake, a storage container with radioactive debris tipped over and asphalt paths at the plant were cracked.