In fact, the top portion of the fuel units became exposed and overheated, leading to the formation of hydrogen gas in a reaction of steam with the zirconium fuel rod casing. Surrounding the reactor is a bell-shaped concrete structure, the primary containment, built to prevent radiation that escapes the reactor from reaching the atmosphere outside the plant.
As hydrogen continued to form, relief valves in the primary containment structure may have opened allowing the gas to exit the primary containment and concentrate in the secondary containment building that surrounds the primary containment, according to U.S. experts familiar with the Japanese reactors.
Compounded by hydrogen explosions
In the General Electric Mark 1 reactor design, the secondary containment structure --a large factory-like outer building --is designed to hold small amounts of gas escaping from the reactor and its primary containment, said David Lochbaum of the Union of Concerned Scientists. But the hydrogen gas concentrated at the top of Unit 1 on Saturday. Something ignited it and the explosion blew off the metal roof over unit 1 at 3:36 pm local time, in a scene viewed worldwide on news reports and social media. The same reaction is believed to have caused the second explosion, at Unit 3, on Monday.
In both cases, the concrete primary containment shell was not damaged, officials reported. However there have been no reports of what happened to metal tanks at the top of the secondary containment building that contains the spent fuel rods, which continue to give off heat and must be cooled by circulating water, Lochbaum said.
"One of the challenges is that the explosion took the roof away. If any of it fell into the [spent fuel] pool, it could either have damaged the fuel," or impaired the water circulation in the pool. "That's the concern that's in play," Lochbaum said Sunday.
Around 8 p.m. Saturday in Japan, Cabinet Secretary Edano announced a high-level decision had been made to inject seawatater into Unit 1. "We've decided to fill the reactor container with sea water. Trade Minister Kaieda has instructed us to do so. By doing this, we will use boric acid to prevent criticality," he said, according to Reuters.
Edano said it the operation would take five to 10 hours initially, and around 10 days to complete the process. Precise details of how the sea water was being piped into the reactor facility were not available Sunday, and it wasn't clear whether crews had succeeded in putting it into the reactor vessel as well as the surrounding primary containment shell.
On Sunday, the same emergency measures were required at the Fukushima Daiichi Unit 3. Toyko Electric (Tepco) said it was unable to restart the reactor's high-pressure water injection system that supplies the reactor core with coolant after it shut down. Tepco then notified the Japanese government of the second emergency at the plant, according to World Nuclear News.
Japan's Nuclear and Industrial Safety Agency (NISA) reported late on Saturday that a gauge measuring water levels inside the No. 3 reactor appeared to be malfunctioning. It was reporting that the tops of the fuel assemblies were uncovered by water and thus vulnerable to failing.
"It is unknown whether [the reading] is real or not," the Japan Atomic Industry Forum (JAIF) said, according to press reports. Other readings contradicted the gauge information, indicating that the threat to the fuel rods was not acute. The order to introduce sea water followed.
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500
See what we're tweeting about
19 Comments
Add CommentIf what's happening in Japan or the cost to build and maintain nuclear power doesn't halt its revival in the U.S. then we have some very stupid people in our government.
Reply | Report Abuse | Link to thisRun away! Run away! pffft!
Reply | Report Abuse | Link to thisYes because earthquakes and tsunami's occur everywhere in the US and instead continue relying on every increasing amounts of dirty fossil fuels is the solution. Nuclear energy can be safe if given a chance to be researched into cleaner more efficient ways of producing it.
Reply | Report Abuse | Link to thisAs America exists today with its bottom line, minimal regulatory oversight, cheapest costs possible...I shudder to think of American businesses properly building to the highest standards possible or maintaining nuclear power plants. And with the libertarian and republican mantras of less government and "it's your problem, you take care of it."
Reply | Report Abuse | Link to thisI wouldn't trust the US gov. and its politicians to do anything in this kind of emergency except leave the country or hold photo op hearings to point the finger of blame at each other
I have no confidence at all in the desire or ability of America's government to answer the need of extreme help should it arise here. Look at Katrina or the republican apologies extended to BP.
It would be an interesting exercise to tally up the fatalities, injuries and environmental damage attributable to the various types of major energy systems (primarily, Oil, Coal, Gas & Nuclear) affected by the quake and tsunami in Japan after the crisis is over.
Reply | Report Abuse | Link to thisSo far the description of the nuclear situation in Japan has been generously leavened with large amounts of speculation, hyperbole and fear mongering. This is partly because good information has understandably been sparse, and partly because we have developed a deep seated primal fear of anything radioactive.
Outside of the media spotlight I see gas and oil conflagrations going on and undoubtedly many burst pipelines. To date, in Japan and the US, the history of *actual* deaths, injuries and environmental damage per unit of energy produced that is attributable to fossil fuels is far higher than that of nuclear power.
When all the hyperbole dies down we'll see if this new crisis changes that equation.
No, don't worry Komrade, natural disasters only happen to everyone else. As we all know, Gawd is American and therefore there is absolutely no chance of any major catastrophe hitting the US.
Reply | Report Abuse | Link to thisToo bad nobody told New Orleans.....
@JamesDavis- James is an example of a person that would throw out the baby with the cold bath water.
Reply | Report Abuse | Link to thisThe nuclear power plants in Japan are 40 year old technology. Do you think we have learned how to do some things better in 40 years? How is your 40 years old computer working? How about that 40 year old television set?
Modern ( 3rd and 4th generation conventional) or thorium reactors are safe and clean as compared to the alternatives available to produce electricity and they do not force countries to but foreign oil of emit CO2.
It is easy to be against anything, but at the end of the day we need electricity and nuclear is probably the best practical choice for America for the next few decades. The US should start standardizing safe designs and building dozens per year. Can lessons regarding how to ensure that electrical back up power is available for cooling in the event of a level 9.0 earthquake...yes
See that's the thing, lack of foresight. Building essential infrastructure in disaster prone areas makes no sense. Honestly no place is 100% perfect but in this vast land I'm sure there is some low risk areas. Irregardless fear mongering over Nuclear is a step backwards. Bottom line it is our more realistic solution to weaning us off our fossil fuel dependence. Of course if you prefer more offshore oil rigs and mountaintop removal techniques in order to feel safer personally I guess I could understand that. Search around this site, it provides a host of new technologies that could be investigated to hinder the chance of another 3 mile or Chernobyl.
Reply | Report Abuse | Link to thisAnd regarding New Orleans...what does that have to do with nuclear power? Talk to FEMA about that or your local congressman.
I thought these reactors were all GE reactors. They are the oldest in Japan I believe and are GE designned and built - GE is a US company.
Reply | Report Abuse | Link to thisJames you know you are right. I know you are right. Politicians are simply corrupt. The Homo sapien is an idiotic self centred species, the biosphere would be better off without.
Reply | Report Abuse | Link to thisLet them build nuclear power plants, the more the better to ensure the early extinction of the destroyer of all life.
Make cigarettes cheaper, remove all chemical bans, allow over the counter purchase of anything any one desires. Now that's freedom. Allow all industry to compete to provide the cheapest product, don't punish industry for loss of property or life, if they can prove the user or employee acted contrary to their terms and conditions of use or employment.
Let the sixth extinction run its course, help it if possible. The nuclear industry is our friend, they help eradicate the idiot Homo sapien.
Nuclear power in an ideal world - designed, built and operated by ideal people - works just fine. But as my brother, a nuclear engineer and former officer on board a USN nuclear submarine, said, if civilian nuke plants were quality-controlled by the Navy, they'd all be shut down. I live close to three major reactors, so I'm not crying NIMBY. However, we have better, safer, and cheaper alternatives: true renewables. Nuclear is not a renewable, because uranium is finite. What do we do when that runs out and we still haven't figured out how to make solar, wind, and wave power as cheap as coal ... of course, coal is far more expensive even now if we account for the external costs (even setting aside climate change) in pollution and health effects, and so is nuclear, if we cost in the risks.
Reply | Report Abuse | Link to thisGrandpa,
Reply | Report Abuse | Link to thisMinimal regulatory oversight in the nuclear industry?
What other Regulations could one possibly make up to make it safer?
Scientific earthling:
Reply | Report Abuse | Link to thisPlease! Do us all a favor and go first.
When the nuclear industry starts to pay for their own disaster insurance and get off Corporate welfare doles, then I will support it. Until then energy efficiency, solar, geothermal, wind, and biofuels are better choices.
Reply | Report Abuse | Link to thisRadiation makes nuclear unclear.
Reply | Report Abuse | Link to thisIt necessitates a level of long-term speculation and prognosis that is absent from other industries. Plus, these forecasts are predominantly made by people at least partially dependent on the existence of a profitable nuclear industry.
So it is breathtakingly naive to believe that the resulting assumptions can sufficiently account for all eventualities for the thousands of years during which they must.
So while the final human tally in Fukushima, Tokai and Ogawa will remain an object of dispute for decades to come, it is already clear that Japan's economy has been dealt a crippling blow by wishful science, via its reliance on nuclear power.
Neither has the Fukushima event run its course, nor will Fukushima stop being problematic after current developments have come to a halt, nor will nuclear power stop being an issue soon after the world's last power plant has been shut down.
Nuclear power's timescale alone, the need to safeguard nuclear waste for thousands of years should disqualify the use of nuclear power as irresponsible human hubris.
Combined with the ready availability of alternatives, and the fiendishly imprecise nature of risk and cost assessment in this field, nuclear power is a prime example of the dangers of human high-handedness.
Even in the (as of 3-15-11) singular Chernobyl incident, the damages are assessed to such a breathtakingly wide variety of results, depending on whom you ask, that the flavour of truth that you pick as your own seems more a matter of industrial religion than factuality.
So given its fuzzy nature and lethal potential - and heeding the fact that most of the science involved was funded by parties with interests in the nuclear industry - the only sane conclusion is to focus our energy on the more easily fathomable and controllable non-/low-CO2 sources available. While doing our best for the safe disposal and monitoring of the residue of this dumb experiment.
My son put things quite well. He said "Anything that takes a magnitude 9 earthquake and a tsunami to damage is safe". I have to agree.
Reply | Report Abuse | Link to thisWill Saletan at Slate has done exactly that math. The whole article comparing our reactions to nuclear and fossil fuel disasters is here http://www.slate.com/id/2288212/, but here's his specific death estimates:
Reply | Report Abuse | Link to this"The sole fatal nuclear power accident of the last 40 years, Chernobyl, directly killed 31 people. By comparison, Switzerland's Paul Scherrer Institute calculates that from 1969 to 2000, more than 20,000 people died in severe accidents in the oil supply chain. More than 15,000 people died in severe accidents in the coal supply chain—11,000 in China alone. The rate of direct fatalities per unit of energy production is 18 times worse for oil than it is for nuclear power.
Even if you count all the deaths plausibly related to Chernobyl—9,000 to 33,000 over a 70-year period—that number is dwarfed by the death rate from burning fossil fuels. The OECD's 2008 Environmental Outlook calculates that fine-particle outdoor air pollution caused nearly 1 million premature deaths in the year 2000, and 30 percent of this was energy-related. You'd need 500 Chernobyls to match that level of annual carnage. But outside Chernobyl, we've had zero fatal nuclear power accidents."
Saletan's math is correct.
Reply | Report Abuse | Link to thisFukushima Units 1 - 5 utilizing the GE Mark I type containment structure were commissioned between 03/71 and 04/78. The sixth unit, utilizing Mark II containment, was commissioned in 10/79.
The safety of the Mark I design was challenged by D. Bridenbaugh and two of his GE colleagues 35 years ago.
At least one better reactor design (the Westinghouse AP1000) exists:
"The AP1000™ pressurized water reactor works on the simple concept that, in the event of a design-basis accident (such as a coolant pipe break), the plant is designed to achieve and maintain safe shutdown condition without any operator action and without the need for ac power or pumps. Instead of relying on active components such as diesel generators and pumps, the AP1000 relies on the natural forces of gravity, natural circulation and compressed gases to keep the core and containment from overheating."
In the spring of 2007 China National Nuclear Corp. selected the Westinghouse/Shaw consortium to build four AP1000 nuclear reactors for an estimated US$8 billion. As of April 2010, those were the only AP1000 units in the world to have started construction.
The NRC has questioned the durability of the AP1000 reactor's shield building in the face of severe external events such as earthquakes, hurricanes, and airplane collisions. A US nuclear consultant engineer has also criticised the AP1000 containment design arguing that, in the case of a design-basis accident, it could release radiation; Westinghouse has denied the claim. The NRC anticipates completing the overall design certification review for the AP1000 around Sept 2011.
Just days before the earthquake in Japan, Rep. Edward Markey of Massachusetts, sent a letter to NRC chairman Greg Jaczko, asking the agency to withhold final approval of a new Westinghouse reactor design due to "serious safety concerns." Markey wrote that an NRC expert had identified "potential loopholes, which, if left open, allow designs for unsafe reactors to go forward despite the risk that an earthquake or aircraft impact could result in a catastrophic core meltdown."
Fourteen reactors based on the AP1000 design are under development in Alabama, Florida, North Carolina, South Carolina and Georgia.
So, nuclear power is relatively safe; the Fukushima design was unsafe; the Westinghouse AP1000 provides safer containment than the GE Mark 1, but several questions remain.
Thus, if several objections to the existing AP1000 design can be removed, nuclear power can be a viable option even after Fukushima.
I apologize for the awkward references, but I was contrained to post no more than 2500 characters at a time.
Reply | Report Abuse | Link to thisLinks to the statements above:
http://en.wikipedia.org/wiki/Fukushima_I_Nuclear_Power_Plant
http://abcnews.go.com/Blotter/fukushima-mark-nuclear-reactor-design-caused-ge-scientist/story?id=13141287
http://www.ap1000.westinghousenuclear.com/ap1000_safety.html
http://en.wikipedia.org/wiki/AP1000
http://www.nrc.gov/reactors/new-reactors/col/vogtle.html
Here's a link to Rep. Markey's letter to the Nuclear Regulatory Commission dated March 7th, 2011.
http://markey.house.gov/docs/3-7-11.ejmtonrc.pdf