TOKYO Fears of a nuclear disaster in Japan heightened on Tuesday after radiation levels around its quake-stricken power plant soared following two separate explosions at the complex.
Many of the worrying milestones mapped out by experts have now been passed, with some workers having left the complex and people living within 30 km of the site to stay indoors.
* Now there is a real possibility of a leak in the reactor container, which houses the nuclear fuel rods, according to Murray Jennex, a professor at San Diego State University in California.
* Concerns center on damage to a part of the reactor core known as the suppression pool, which helps to cool and trap the majority of cesium, iodine, strontium in its water.
* It is unclear what is the nature of the damage and its impact on the integrity of the containment structure, a thick steel vessel that surrounds the core.
* It is possible that the containment structure is not damaged, but any damage to the suppression pool could affect the ability to mitigate pressure inside.
* Jennex suspects two possible problems: a water leak or perhaps valve leak. A valve leak would be better because that would be less difficult to fix than a water leak, he said.
* Japan's nuclear crisis now appears worse than the Three Mile Island nuclear accident in 1979 but still nowhere near as bad as the Chernobyl disaster in Ukraine in 1986.
* Neighboring countries could be the first to sound the wider alarm about a major radioactive leak, as happened with Chernobyl. In Japan's case, that would most likely be South Korea, China or Russia.
(Reporting by Elaine Lies; Editing by Mark Bendeich)