This article, posted yesterday, at the BBC seems to have the best summary on the situation at the Fukushima Daiichi reactor. Here are the key points.
Some supposedly redundant safety systems failed. Whether a meltdown is underway is not yet clear, but the control rods (we are told) are still in place. No significant radiation has yet been detected, but the presence of cesium is worrying.
BUT! All of this depends on the information coming from the operators of the plant. And…
As with its counterparts in many other countries, Japan’s nuclear industry has not exactly been renowned for openness and transparency.
Tepco itself has been implicated in a series of cover-ups down the years.
In 2002, the chairman and four other executives resigned, suspected of having falsified safety records at Tepco power stations.
Further examples of falsification were identified in 2006 and 2007.