Excellent article explaining the situation at the Fukushima plant

[CNiko]

Re: Excellent article explaining the situation at the Fukushima plant

Gentlemen:

I find it very hard to believe they do not have several layers of redundancy concerning keeping the reactor core covered with water and coolant flowing.

randy

There are several redundant layers, some of them are : Off site power, cross-tie power with the other on site units, and redundant Diesel Generators. Some plants also have the ability to release water from storage ponds by gravity. I did not see this last option on the aerial photo of the plant in question. The first two sources failed in the Earthquake and the Diesel generators got submerged by the waves. The Coolant pumps are high voltage equipment, and can't be powered by Batteries, same with the Residual Heat Removal pumps. The batteries are generally used with an inverter system to power small loads such as Instrumentation, controls etc.. The damage to the piping system from the earthquake is unclear from the reports. From the aerial picture after the explosion of the first unit it does not appear there was any extensive damage to the inner containment structure, unclear on the second unit which blew up. Also it is unclear what the damage to the spent fuel pools was. I am not sure of this, but they probably uncovered the spent fuel after the explosions, and sent some of the stuff flying, this could be the airborne radiation / contamination source. The reactor cores were probably already beyond saving once they decided to start pumping the sea water. The news reports are pretty bad with some sources trying to outdo others and reporting inaccurate information.

CN

[Starving Steve]

Re: Excellent article explaining the situation at the Fukushima plant

You can bury the plutonium into the granite, under my house. But please pay me rent so that I might have some income to survive this economic down-turn.

[bagginz]

Re: Excellent article explaining the situation at the Fukushima plant

I find it very hard to believe they do not have several layers of redundancy concerning keeping the reactor core covered with water and coolant flowing.

The chain of failures illustrates the capacity of events such as this massive earthquake and tsunami to overwhelm systems that are designed to be "redundant" - to have more than one means of doing the same thing.

The earthquake caused Fukushima Daiichi and other power stations to shut down - taking away the electricity driving the reactors' cooling systems.

Back-up was supposed to come from diesel generators. They cut in - but then cut out again after about an hour, probably due to being overwhelmed by water from the tsunami, although Tepco has not confirmed this.

The diesels themselves were backed up further by batteries, but these were designed to function only for eight hours. When they ran out, nothing else was available.

Reports say that five fire pumps were then deployed to provide water, but that the explosions in buildings 1 and 3 knocked four of them out of action.

Meanwhile, devastation from the tsunami as well as the fear of aftershocks means simply driving new pumps or fuel to the site is much more difficult than it would be under normal circumstances.

Full article: http://www.bbc.co.uk/news/science-environment-12737508

[seanm123]

Re: Excellent article explaining the situation at the Fukushima plant

peak explosions?


The sound of a blast was heard Tuesday morning at the troubled No. 2 reactor of the quake-hit Fukushima No. 1 nuclear power plant, the government said.

The incident occurred at 6:10 a.m. and is feared to have damaged the reactor's pressure-suppression system, the Nuclear and Industrial Safety Agency said, citing a report from the plant's operator Tokyo Electric Power Co.

==Kyodo

[don]

Re: Excellent article explaining the situation at the Fukushima plant

The article in question mentions that the diesel generators were wrecked by the tsunami - not the earthquake.

Given that a 15 foot wall of water hit the coast of Japan, possibly higher, and Fukushima sits right on the shoreline, this seems quite consistent.

EJ reports that "the tsunami sent a wave of water 25 feet high at 250 MPH into the intake systems, destroying them and the on-site power systems."

[ASH]

Re: Excellent article explaining the situation at the Fukushima plant

peak explosions?


The sound of a blast was heard Tuesday morning at the troubled No. 2 reactor of the quake-hit Fukushima No. 1 nuclear power plant, the government said.

The incident occurred at 6:10 a.m. and is feared to have damaged the reactor's pressure-suppression system, the Nuclear and Industrial Safety Agency said, citing a report from the plant's operator Tokyo Electric Power Co.

==Kyodo

If they can't vent to relieve pressure, that could be... problematic.

[Jam]

Re: Excellent article explaining the situation at the Fukushima plant

It will keep you warm and cozy during those cold Canadian winters ;)

[Jam]

Re: Excellent article explaining the situation at the Fukushima plant

Very informative article. However, for all the bitching about errors in previous reports, the author did not check his math and inserted errors of his own

The earthquake that hit Japan was 7 times more powerful than the worst earthquake the nuclear power plant was built for (the Richter scale works logarithmically; the difference between the 8.2 that the plants were built for and the 8.9 that happened is 7 times, not 0.7).

On Richter scale, the difference of 0.7 (M_L) corresponds to a factor of ~5 (10^0.7 =~ 5), as in 'five times more powerful.' http://en.wikipedia.org/wiki/Richter_scale.

On the modern Moment Magnitude Scale (MMS), the difference of 0.7 (M_w) corresponds to a factor of ~11.22, as in '11 times more powerful.' http://en.wikipedia.org/wiki/Moment_magnitude_scale.

[thriftyandboringinohio]

Re: Excellent article explaining the situation at the Fukushima plant

If they can't vent to relieve pressure, that could be... problematic.

Your earlier excellent post shows the "...pressure-supression system" is the big torus vessel at the bottom and its big radial feed pipes.

"..damaged..the.. pressure-supression system" probably means a leak. The "system" appears to have no active components like motors or valves, it's just a huge toroidal tank of water with pipe connections. If your "system" is a tank, the only failure mode is "leak". Looks like a lot of academic papers have been written about earthquakes creating big sloshing forces in these gizmos that could break them. ( I didn't actually READ any of these papers).

[c1ue]

Re: Excellent article explaining the situation at the Fukushima plant

Very informative article. However, for all the bitching about errors in previous reports, the author did not check his math and inserted errors of his own

The source of the article is: http://morgsatlarge.wordpress.com/20...lear-reactors/

At this location it is updated, and has the correct numbers.

It has since moved to MIT's Nuclear Science and Engineering web site:

http://mitnse.com/

This was posted in the first Japan Nuclear Reactors thread which has been moved.

[ASH]

Re: Excellent article explaining the situation at the Fukushima plant

If your "system" is a tank, the only failure mode is "leak".

It's being reported that pressure dropped, and external radiation level increased, following the explosion. Sounds like the containment is breached. That suggests to me that we may face uncontrolled venting of gas and fluid, and the potential for seriously contaminating the local area, down the road.

[oddlots]

Re: Excellent article explaining the situation at the Fukushima plant

Yes, apart from using the wrong designs and the wrong fuel, I love nuclear energy. (I'm not being facetious.)

Fuel: thorium. Design: low pressure systems like pebble bed-reactors.

Much of the massive cost of nuclear comes from building massive containment structures required by high-pressure systems (and prudence). And more importantly, much of the risk: squinting hard I'd say that the problem with most conventional nuclear plants is that they place a high pressure system next to a nuclear pile that contains immensely poisonous elements. Basically "dirt" pile moves in next to the "bomb" family and is just dying to get introduced. The key to me seems to be to take the high-pressure out of the equation. The article that convinced me of this - FWIW - is here:

http://www.wired.com/wired/archive/12.09/china.html

As for thorium, my understanding is that it all but eliminates 1) worries about nuclear proliferation (you can't get fissionable bomb material out of thorium) 2) less (zero-can't remember?) waste: thorium seems to eat it's tail so to speak.

Kinda sketchy I know but haven't bee thinking about this stuff again until recently.

[Chomsky]

Re: Excellent article explaining the situation at the Fukushima plant

It's being reported that pressure dropped, and external radiation level increased, following the explosion. Sounds like the containment is breached. That suggests to me that we may face uncontrolled venting of gas and fluid, and the potential for seriously contaminating the local area, down the road.

Catastrophe imminent.

http://www.nytimes.com/2011/03/15/wo...uclear.html?hp

[Chomsky]

Re: Excellent article explaining the situation at the Fukushima plant

http://bravenewclimate.com/2011/03/1...e-explanation/

Alarmists will be disappointed.

Catastrophe imminent. So much for this guy's cred.

http://www.nytimes.com/2011/03/15/wo...uclear.html?hp

[thriftyandboringinohio]

Re: Excellent article explaining the situation at the Fukushima plant

It's being reported that pressure dropped, and external radiation level increased, following the explosion. Sounds like the containment is breached. That suggests to me that we may face uncontrolled venting of gas and fluid, and the potential for seriously contaminating the local area, down the road.

There are degrees of everything. I think it remains unlikely that uranium or plutonium (for the MOX reactor) would ever leave the building. But seeps or ejections of vapors might be expected, and they'll have radioisotopes in them.