Union of Concerned Scientist's statement regarding the nuclear crisis in Japan

[snagglepuss]

snip

The situation is still evolving, but below is a preliminary assessment based on the facts as experts at the Union of Concerned Scientists currently understand them.

snip

This power failure resulted in one of the most serious conditions that can affect a nuclear plant—a “station blackout”—during which off-site power and on-site emergency alternating current (AC) power is lost. Nuclear plants generally need AC power to operate the motors, valves and instruments that control the systems that provide cooling water to the radioactive core. If all AC power is lost, the options to cool the core are limited.

The boiling water reactors at Fukushima are protected by a Reactor Core Isolation Cooling (RCIC) system, which can operate without AC power because it is steam-driven and therefore does not require electric pumps. However, it does require DC power from batteries for its valves and controls to function.

If battery power is depleted before AC power is restored, however, the RCIC will stop supplying water to the core and the water level in the reactor core could drop. If it drops far enough, the core would overheat and the fuel would become damaged. Ultimately, a “meltdown” could occur: the core could become so hot that it forms a molten mass that melts through the steel reactor vessel. This would release a large amount of radioactivity from the vessel into the containment building that surrounds the vessel.

snip

Bloomberg News reported that the battery life for the RCIC system is eight hours. This means that the batteries would have been depleted before 10 a.m. EST today. It is unclear if this report is accurate, since it suggests that several hours have elapsed without any core cooling. Bloomberg also reported that Japan had secured six backup batteries and planned to transport them to the site, possibly by military helicopter. It is unclear how long this operation would take.

There also have been news reports that Fukushima I Unit 2 has lost its core cooling, suggesting its RCIC stopped working, but that the situation “has been stabilized,” although it is not publicly known what the situation is. TEPCO reportedly plans to release steam from the reactor to reduce the pressure, which had risen 50 percent higher than normal. This venting will release some radioactivity.

UCS will issue updates as more information becomes available.






http://www.ucsusa.org/news/press_release/nuclear-crisis-in-japan-fukushima-0518.html?utm_source=SP&utm_medium=more&utm_campaign=japan-nuke-crisis-3-11-11-more

[sasha031]

1. K&R and bookmark for later

[Tansy_Gold]

3. Ditto

[tabatha]

2. Thanks, I'll take their word over any other.

[drm604]

4. This is not encouraging.

It sounds quite ominous. :hide: