The threat of a radiation leak from Japan’s Fukushima nuclear plant has become real. On Saturday, the building housing reactor number one blew.
That was followed by another large explosion at the site’s reactor number 3 on Monday. Despite serious concerns, scientists suspected the blasts at the TEPCO owned facility were hydrogen powered and not radioactive.
Kaoru Yoshida, a spokesman for TEPCO, said:
“There was a loud noise from the reactor nº3 at 11:01 a.m. and some white smoke. We think it was a hydrogen explosion.”
The Fukushima power plant was designed to withstand big earthquakes. So what has gone wrong and why have the facilities back-up systems failed?
Like all nuclear sites, the reactors must always be kept cool. This is done by pumping water into the core. Not doing so, would result in the reactor rods overheating, eventually leading to a meltdown.
When the massive 8.9 magnitude tremor struck on Friday, Fukushima Daiichi’s reactors’ shut down as planned, but a power cut also stopped the facilities main cooling systems.
The plant’s first back up, powered by on site generators, kicked in to keep the reactor cores cool. But after an hour these stopped working. Experts believe they were damaged in the devastating Tsunami that followed the quake.
The Fukushima facilities’ second back-up was activated. This converted steam building up inside the core and pumped it back again as cold water. But, this also failed, resulting in the water level dropping and the reactor’s rods being exposed. The reason for this failure is unclear, but experts say the most probable cause was a leak inside the reactors, allowing water to escape.
In a desperate bid to stop the meltdowns, engineers started pumping in sea water. By now, all of the power station’s reactors that were operating on Friday had been affected. Like one and three, reactor number two exploded. But, unlike the others, this blast is believed to have breached the inner containment core causing a radiation leak. A fire also broke out at reactor number four despite it being shut for maintenance. The risk of contamination is thought to be high.
The race to cool the reactors continues, but the nuclear accident at Fukushima is starting look like the world’s worst since Chernobyl, in Soviet Ukraine in 1986.