French nuclear agency rates Japan accident 5 or 6

French nuclear agency rates Japan accident 5 or 6
14 Mar 2011 16:17
Source: reuters // Reuters

PARIS, March 14 (Reuters) - France's ASN nuclear safety authority said on Monday the nuclear accident in Japan could be classed as level 5 or 6 on the international scale of 1 to 7, on a par with the 1979 U.S. Three Mile Island meltdown.

The estimate of the severity of the accident at Tokyo Electric Power Co's Fukushima Daiichi plant, based on the ASN's assessment of data provided by Japan, is above the rating of four given by Japan's nuclear safety agency.

"Level four is a serious level," ASN President Andre-Claude Lacoste told a news conference, but added: "We feel that we are at least at level five or even at level 6."

Japan is struggling to cope with a crisis caused by a huge earthquake and tsunami on Friday that crippled three reactors at the TEPCO plant and raised fears there might be a serious radiation leak. (Reporting by Mathile Cru, editing by Tim Pearce)

http://www.trust.org/alertnet/news/french-nuclear-agency-rates-japan-accident-5-or-6/

The Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in the Ukrainian SSR (now Ukraine). It is considered the worst nuclear power plant accident in history, and it is the only one classified as a level 7 event on the International Nuclear Event Scale.

The disaster began during a systems test on 26 April 1986 at reactor number four at the Chernobyl plant, which is near the town of Pripyat. There was a sudden power output surge, and when an emergency shutdown was attempted, a more extreme spike in power output occurred, which led to a reactor vessel rupture and a series of explosions. This event exposed the graphite moderator components of the reactor to air, causing them to ignite. The resulting fire sent a plume of radioactive fallout into the atmosphere and over an extensive geographical area, including Pripyat. The plume drifted over large parts of the western Soviet Union, Eastern Europe, Western Europe, and Northern Europe. Large areas in Ukraine, Belarus, and Russia had to be evacuated, and over 336,000 people were resettled. According to official post-Soviet data,<1><2> about 60% of the fallout landed in Belarus.

Despite the accident, Ukraine continued to operate the remaining reactors at Chernobyl for many years. The last reactor at the site was closed down in 2000, 14 years after the accident.<3>

The accident raised concerns about the safety of the Soviet nuclear power industry as well as nuclear power in general, slowing its expansion for a number of years and forcing the Soviet government to become less secretive about its procedures.<4>


http://en.wikipedia.org/wiki/Chernobyl_disaster

You've got to have a significant containment failure on one of the reactors to get to a six.

I said yesterday that I thought a five was warranted if only because there are now at least three 4's happening simultaneously. TMI was a five and I don't think that this event is LESS significant than TMI at this point.

Of course there's room to get worse, but if you take a look at the only recorded INES level six (Kyshtym disaster at Mayak, Soviet Union), there was an explosion that sent 60-70 tons of extremely radioactive material into the environment.

...that this is at least as significant as TMI, which was categorized as a Level 5.

There are some pesky facts that IMO elevates the current situation to a 6 IMO (despite the formal criteria you cite):

1 - Not just one, but two hydrogen gas explosions that blew apart the building around the reactors and damaged equipment meant to help control the reactor -- this never occurred at TMI

2 - Damage from an earthquake and tsunami that has taken needed backup systems offline -- while TMI had malfunctions, the equipment was not destroyed and taken offline

3 - The continuing threat of further damage from aftershocks or even another earthquake -- there was no natural disaster at TMI contributing to the situation

So I think this has already gone well beyond TMI in its seriousness.

Prayers to the people of Japan, who are already suffering from the destruction of the earthquake and tsunami; and special prayers to those heroic people at the stricken plants who are trying to avert an even worse catastrophe.

That is... they're all ways that this is a more serious challenge than TMI.

But at levels four and above, all the INES scale really cares about is radioactive release and health threat to the population. Even a five is supposed to involved dozens of people dying from radiation exposure. To date, there are no reports hinting that this is happening.

But yeah, as an overall event it's more significant than TMI (while still lost in the even more significant events of this week).

Prayers are indeed warranted... and offered up.