Engineers Find Nuclear Meltdown At Fukushima Plant 664
fysdt writes "Engineers from the Tokyo Electric Power company (Tepco) entered the No.1 reactor at the end of last week for the first time and saw the top five feet or so of the core's 13ft-long fuel rods had been exposed to the air and melted down. Previously, Tepco believed that the core of the reactor was submerged in enough water to keep it stable and that only 55 per cent of the core had been damaged."
Re:Nuclear power arguments (Score:3, Informative)
NHK is reporting it differently (Score:5, Informative)
Re:nuclear can be safe; short term profit preferre (Score:5, Informative)
Some of the pollutants that burning coal dumps into the air? Radioactive uranium.
http://www.scientificamerican.com/article.cfm?id=coal-ash-is-more-radioactive-than-nuclear-waste [scientificamerican.com]
Re:Nuclear power arguments (Score:3, Informative)
But coal power is also handled by an organization with a profit motive.
They emit more radiation [scientificamerican.com] than nuclear power plants, too.
Re:Nuclear power arguments (Score:5, Informative)
The problem wasn't the technology or the construction. The only flaw I saw in the entire setup was that the system SCRAM'd without backup power to run the cooling system. What this failure points out is a critical failure in site planning and design for site specific conditions. This reactors was built at sea level on the side of the island hit more times than any other by Tsunami's where there are 600 year old (600!) markers saying don't build below this point because a Tsunami destroyed everything below the marker and it appear that although they took into account earthquake engineering they didn't even account for a Tsunami hitting the plant.
Had they taken the Tsunami incident into account they could have either built the plant with sea walls and significant concrete protection for the generators and backup systems or they could have built the plant above the markers. They did neither, so the reactors began building up latent heat from the reactions when the backup cooling system and generators were destroyed by the Tsunami. The key thing here though is that the safety systems and containment vessels prevented a full blown disaster. Sure there was radiation released that will wash into the ocean and dissipate entirely within a year. Sure the reactors have been poisoned and ruined and many people have been displaced but outside the plant operators there will likely not be a single death from radiation. That's an amazing achievement given the glaring site and design problem.
The point of this disaster and what people need to learn isn't that nuclear is bad, it's that site specific conditions need to be taken into account when designing the plant. You need to design for the 100 year storms and disasters to be fully avoided and make preparations and planning probably out to the 500-1000 year events. (for those that aren't aware thats the re-occurrence interval. It doesn't mean it happens every 500 years, it means there is a 1/500 chance of it happening that year). What needs to happen in Japan is an inquiry into why this plant was built at this site (in particular given those 600 year old monuments up the hill from the plant), why it wasn't designed to survive a Tsunami and Earthquake of this magnitude and what happened to make all this possible. Then they need to evaluate every other plant and it's site and make sure they are all designed to survive natural disasters. It's easy for the press to focus on the scary of the nuclear aspect while ignoring the site and engineering failures that made this accident possible.
You can't simply take a "safe" design and slap it down at any location without taking into account local and regional disasters and site specific conditions that could compromise the safety systems. This is basic engineering and how this plant was built at this location without accommodations for a Tsunami is astounding to me.
Re:Nuclear power arguments (Score:4, Informative)
Well, the media may not be picking it up, but there's lots of environmentalist types complaining about the use of coal-fired plants too, due to the fact that it's one of the biggest sources of CO2 emissions contributing to global warming, and can turn the areas near where it's mined into wastelands.
The green folks are pretty clear on what they want to see: widespread use of wind and solar power.
Re:nuclear can be safe; short term profit preferre (Score:4, Informative)
They actually produce very little waste (much less than the crap spewing from coal or from producing solar panels). Go education yourself here: http://online.wsj.com/article/SB123690627522614525.html [wsj.com]
Key quote:
Re:nuclear can be safe; short term profit preferre (Score:5, Informative)
cadmium, copper-indium, gallium arsenide, polyvinyl fluoride, etc.
Re:Nuclear power arguments (Score:5, Informative)
Had they taken the Tsunami incident into account they could have either built the plant with sea walls and significant concrete protection for the generators and backup systems or they could have built the plant above the markers.
In fact, they had seawalls, but they were built for 12 m tsunami waves. From wikipedia:
Although Japan has invested the equivalent of billions of dollars on anti-tsunami seawalls which line at least 40% of its 34,751 km (21,593 mi) coastline and stand up to 12 m (39 ft) high, the tsunami simply washed over the top of some seawalls, collapsing some in the process. [wikipedia.org]
and
The remaining reactors shut down automatically after the earthquake, with emergency generators starting up to run the control electronics and water pumps needed to cool reactors. The plant was protected by a seawall designed to withstand a 5.7 m (19 ft) tsunami but not the 14 m (46 ft) maximum wave which arrived 41â"60 minutes after the earthquake. [wikipedia.org]
Feed and Bleed (Score:5, Informative)
TEPCO are doing "feed and bleed" -- they are pumping between 6 and 9 tonnes of water an hour into the reactors and then extracting it again to remove decay heat from the cores. Step 2 is to build a self-contained cooling loop in each reactor building starting with reactor 1 that will circulate cooling water rather than doing feed and bleed. Step 3, if it is possible, will be to restore the original cooling loop systems through the seawater condensers under the turbine buildings beside the reactors. That can only be done when the loops are fully functional again and that will take a lot more time to achieve.
They are also planning to flood the secondary containments to immerse the reactor vessels in a large heatsink of water to further cool the reactor vessel itself. This will only be done when and if they are sure the containments are watertight.
Bad Summary and Terrible Article (Score:4, Informative)
Among other things engineers certainly did not enter the containment vessel and see the condition of the nuclear rods.
The Japan Times seems to have been a little more careful to get things correct.
http://search.japantimes.co.jp/cgi-bin/nn20110513a1.html [japantimes.co.jp]
Re:nuclear can be safe; short term profit preferre (Score:5, Informative)
I don't really disagree with you, but there is one part of solar energy you missed. Solar Thermal power doesn't use those hazardous chemicals, it uses mirrors shining on a tower full of salt to store heat as liquid salt which is then used to boil water and produce power. It is much less dangerous, but still you lose land to it.
http://en.wikipedia.org/wiki/Solar_thermal_energy [wikipedia.org]
specifically: http://en.wikipedia.org/wiki/Solar_thermal_energy#Power_tower_designs [wikipedia.org]
Re:Nothing to see here (Score:3, Informative)
In the case of Three Mile Island, and with approximately 50% of the rods in meltdown, the walls of the reactor pressure vessel were ablated about 5/8" (out of of a total wall thickness of 9"). So, yes a containment vessel can contain the material. Actually, considering that in just about 2 minutes, 15,000lbs of Corium (that molten mass of melted fuel, cladding, steel, and other fun stuff) was formed and pooled in the pressure vessel, a loss of just 5/8" of thickness is pretty impressive.
Now in the case of Chernobyl, the Corium was released and flowed downward. This Corium flow didn't make it outside of the facility build and into native earth though.
Re:nuclear can be safe; short term profit preferre (Score:4, Informative)
And of those three:
1979: No actual measurable public radiation exposure. Some animals did have measurably elevated levels of radioactive substances, but if you drank that milk for a year you'd receive 1/75 the dose you would from eating a banana daily
1986: Not an accident but a dangerous experiment gone wrong on a fundamentally unstable reactor design with no containment provisions whatsoever. Try to build an RBMK near me and I'll fight it tooth and nail.
2011: Required a disaster that outright killed 25,000+ people in order to trigger problems
Re:nuclear can be safe; short term profit preferre (Score:5, Informative)
Just a small correction: we don't really know how many victims Chernobyl made. The '50 fatalities' figure was at some point an official Soviet figure, which included only about 47 workers who died of acute radiation poisoning, and is hopelessly optimistic.
The WHO and the AEIA estimates the number of direct victims of Chernobyl to 4,000 [who.int], but this figure is suspected to be low, as the AEIA has vested interests in the nuclear industry.
The TORCH report (The Other Report of CHernobyl) [greens-efa.org], commissioned by the European Green Party, estimate about 60,000 extra cancers deaths due to Chernobyl. This figure does not include non-fatal cancers, which still have notable effect on victims.
A recent book, written by reputed scientists and based over 5,000 survey, puts the number of victims at about one million [climateandcapitalism.com]. Of course, some people disagree with this figure [blogspot.com], however, there is no doubt that the scope of the accident was massive, and continues to make victims today.
The Ukrainian government has claimed in 2006 that more than 2.4 million people, including 500,000 children, have suffered adverse health effects from the Chernobyl disaster. This does not include the effect on people displaced due to the disaster. Of course the Ukrainian people are the ones left with the very hot potato and they would dearly like some help.
Also you may want to take a look a this photo essay [magnumphotos.com] and reflect on your "50 victims" figure. The bottom line is that there were definitely way more victims than the 50 you claim, and quite possibly way way more.
I'm right now totally in favor of nuclear energy, but we need to all understand the very significant risks, and try to mitigate them as much as possible.