When the quake struck, it damaged four power plants on Japan’s east coast. Three have been stabilized, but the situation at Fukushima-Daiichi has deteriorated, sparking fear of a full-fledged nuclear meltdown. Here’s the latest.
(More on TIME.com: See how to help victims of the earthquake in Japan)
First, some background:
Japan has 18 nuclear power plants, which together house a total of 54 reactors. These plants generate about 29 percent of the country’s electricity.
The Fukushima-Daiichi plant is situated on Japan’s east coast, near the town of Okuma. It is one of the 25 biggest nuclear power stations in the world and contains six reactors.
Here’s what’s happened so far:
REACTOR UNIT 1: There was an explosion in Unit 1 on Saturday. The blast tore off the wall and roof of the outer containment vessel, but reportedly left the reactor intact. Four people were injured in the blast and locals were subsequently ordered to leave the area. The reactor has since been filled with seawater to cool it down.
REACTOR UNIT 2: Late Monday night, workers noted that the unit was unstable. They injected seawater to avoid further damage to the reactor, but it didn’t work: an explosion occurred the following morning at 6 a.m. The blast damaged the inner steel containment vessel and the cores of both reactors may have partially melted. It was then that Japanese officials acknowledged that radiation levels were becoming dangerous. The bulk of the plant’s staff were asked to leave, though a small crew, now called the Fukushima 50, stayed back.
REACTOR UNIT 3: Right after the explosion at Unit 1, a hydrogen explosion occurred at the third reactor, tearing away the outer frame of the building. Currently, the third unit is under inspection and not operational.
REACTOR UNIT 4: Reported to be offline at the time of the tsunami, Unit 4 caught fire on Tuesday morning. That occurred shortly after the explosion at Unit 2. The reactor erupted as a result of pressure buildup within the structure again on Wednesday, setting the outer walls ablaze. Fire and smoke can no longer be seen, but Japanese nuclear agency officials were unable to confirm if the fire has been put out. In order to contain the incident, they are spraying seawater and boric acid over the structure.
REACTOR UNIT 5 & 6: Nothing has occurred at the fifth and sixth reactors. Both units were not operating when the quake hit.
(via New York Times)