depends of the probability of stuff happening, I guess. One thing I know: the very best and safest reactors of the latest kind would make a huge difference in premium.
Yes; it’s a late-60’s US (General Electric) design, boiling water reactor. Reactor #3 is MOX fuelled (1, 2 and 4 are burn uranium oxide).
No. They just don’t build nuclear weapons. They have plenty of nuclear power plants.
Btw, the cost to build a nuclear power plant is so high that none would be built without subsidy. It’s all about “green” and “energy independence”.
awaiting more from SkarnailLW
Well, give me some questions and I will do my best to answer them, Justin D.
These particular plants are designed differently than the two types I worked with. The Navy is far more paranoid about nuclear power than you might imagine. And because cost is little object to the Government, the safety measures they take are far more extreme than what civilian plants might (in terms of radioactivity release, etc).
It is very hard to get the real facts of what is going on, to interpret what the japanese engineers are trying to do. From what I can tell, they are trying to bleed excess pressure from the plant to prevent the last containment from failing. Additionally because its a BWR instead of a PWR, the upper most portions of the core are resisting cooling efforts. A partial meltdown is what occured at TMI, damage to the fuel elements resulting in fission product release to the coolant.
However, the longer things go, the better the situation should get, in terms of decay heat.
Also as they vent pressure, most of what is released is hydrogen and water vapor. At high pressure and temperature, Hydrogen reacts violently in air, and thus explodes. Shouldn’t be a problem unless it damages the relief valves or the containment itself.
Also since I don’t build them, I am not sure to their actual construction costs, and how much that is vice complying with the reams of regulations and so forth. Of course, there isn’t a free market in energy at all, so its pretty moot at this point. I have heard start up times ranging from 7 to 10 years just due to all the required hoops, and that most of the cost is frontended, as uranium isn’t that expensive yet. We haven’t built one since 1979, and only have 1 even in the process of being built (here in GA), which will probably get derailed by this.
I personally dont (not yet atleast), i was subscribing to the thread to get automatic updates. I am passing your words on another forum I visit though if thats ok(I am not taking credit). I’ll let you know if they have questions.
Well, just don’t hype my credentials. I was a technician, not a full engineer or anything. Currently in school for a Chemical engineering degree, and may possibly go back into the nuclear field, but not certain about it. Had about 5 years experience working on two plant configurations (trained on S5W - Submarine 5 Westinghouse. Worked on the S8G - Submarine 8 General Electric - used in Trident Ballistic Subs).
Guess its public domain now, try not to talk too much about this stuff, some is classified Confidential and/or Secret.
No hype, I told them exactly what you were and its far better than the few EE and IE’s on that forum (its a car forum). I actually know a Navy Nuclear Tech, but he’s is may be the dumbest person I have ever met (he put nitrous oxide into 11.5:1 compression 4cyclinder engine, thinking it would be a good idea…kaboom) so Id rather ask you.
What are the extents of “civilian plants” in the US? You said the Government ones with their unlimited budgets are safer, but Id like to know compared to what.
Hate to just give you links, but I am not very familiar with the civilian side of things. For one thing, they don’t have to worry about certain events that are more likely on a ship or submarine (torpedos, flooding, etc), so they can focus on nuclear casualties (loss of coolant, steam leaks, etc). Additionally their radiation standards are a bit more lax (the Navy has been obsessed since Rickover with minimizing exposure to the max extent possible, beyond reason in some cases.) so the radiation shielding might be less stringent (probably varies state by state).
Also they are a bit more lax with radioactive liquid discharges, just diluting with water until you reach the EPA limit and then discharging (or so I have heard). Whereas on a vessel, they usually pump those to a tank and hold them for extended period and preferably pump to a shore facility, if its really hot. Depending on plant type and age, the level of activity in a discharge is probably not significantly higher than ocean itself (and is tracked). Discharges are purified and filtered of course prior to discharge to sea.
Generally speaking PWRs are safer than BWRs, but are less efficient and more costly. This is due to the energy loss of using two loops (Primary and Secondary), which allows you to make the radioactive portion smaller, and also allows you to keep the majority of the loop ‘solid’ or filled with pressurized liquid water. In a BWR it seems that some portion of the loop is steam (to drive the turbines), and so you have to take the coolant closer to a critical temperature (and thus closer to core damage).
Nuclear energy is awesome. It’s the safest, cleanest, most abundant energy source available. People don’t like it because “nuclear” sounds scary. Like the bomb. Hence that stupid anti-nuclear movement in the 70’s, that we have to thank for getting half of our electricity from coal now. As for nuclear waste, there is actually very little of the dangerous high-level nuclear waste produced. And it only has a half-life of about 10 years, after which it becomes meadium-level waste, which could safely be stored in individiual households. In fact, a family of four in an all-nuclear energy economy would only produce about two kilograms of nuclear waste in an entire lifetime (280 pearson years).
Hey Skarn, I was asked to get your opinion on this article from ABC news if that’s ok-
Fukushima: Mark 1 Nuclear Reactor Design Caused GE Scientist To Quit In Protest
Damaged Japanese Nuclear Plant Has Five Mark 1 Reactors
Thirty-five years ago, Dale G. Bridenbaugh and two of his colleagues at General Electric resigned from their jobs after becoming increasingly convinced that the nuclear reactor design they were reviewing – the Mark 1 – was so flawed it could lead to a devastating accident.
Questions persisted for decades about the ability of the Mark 1 to handle the immense pressures that would result if the reactor lost cooling power, and today that design is being put to the ultimate test in Japan. Five of the six reactors at the Fukushima Daiichi plant, which has been wracked since Friday’s earthquake with explosions and radiation leaks, are Mark 1s.
“The problems we identified in 1975 were that, in doing the design of the containment, they did not take into account the dynamic loads that could be experienced with a loss of coolant,” Bridenbaugh told ABC News in an interview. “The impact loads the containment would receive by this very rapid release of energy could tear the containment apart and create an uncontrolled release.”
The situation on the ground at the Fukushima Daiichi plant is so fluid, and the details of what is unfolding are so murky, that it may be days or even weeks before anyone knows how the Mark 1 containment system performed in the face of a devastating combination of natural disasters.
But the ability of the containment to withstand the events that have cascaded from what nuclear experts call a “station blackout” – where the loss of power has crippled the reactor’s cooling system – will be a crucial question as policy makers re-examine the safety issues that surround nuclear power, and specifically the continued use of what is now one of the oldest types of nuclear reactors still operating.
GE told ABC News the reactors have “a proven track record of performing reliably and safely for more than 40 years” and “performed as designed,” even after the shock of a 9.0 earthquake.
Still, concerns about the Mark 1 design have resurfaced occasionally in the years since Bridenbaugh came forward. In 1986, for instance, Harold Denton, then the director of NRC’s Office of Nuclear Reactor Regulation, spoke critically about the design during an industry conference.
"I don’t have the same warm feeling about GE containment that I do about the larger dry containments,‘’ he said, according to a report at the time that was referenced Tuesday in The Washington Post.
"There is a wide spectrum of ability to cope with severe accidents at GE plants,‘’ Denton said. "And I urge you to think seriously about the ability to cope with such an event if it occurred at your plant.‘’
Bridenbaugh Believes Design Flaws Were Addressed At Fukushima Plant
Bridenbaugh told ABC News that he believes the design flaws that prompted his resignation from GE were eventually addressed at the Fukushima Daiichi plant. Bridenbaugh said GE agreed to a series of retrofits at Mark 1 reactors around the globe. He compared the retooling to the bolstering of highway bridges in California to better withstand earthquakes.
“Like with seismic refitting, they went back and re-analyzed the loads the structures might receive and beefed up the ability of the containment to handle greater loads,” he said.
When asked if that was sufficient, he paused. “What I would say is, the Mark 1 is still a little more susceptible to an accident that would result in a loss of containment.”
ABC News asked GE for more detail about how the company responded to critiques of its Mark 1 design. GE spokesman Michael Tetuan said in an email that, over the past 40 years, the company has made several modifications to its Mark 1 reactors in the U.S., including installing “quenchers” and fortifying the steel structures “to accommodate the loads that were generated.” He said that GE’s responses to modifications ordered by the Nuclear Regulatory Commission were also shared with the Japanese nuclear industry.
Bridenbaugh told ABC News that he is watching the events in Japan with a mix of anxiety and deep reflection. Many years have passed since he and fellow GE colleagues Gregory C Minor and Richard B. Hubbard publicly resigned, joined the anti-nuclear movement, and became known as the “GE Three.”
Undoubtedly, he said, the containment structures at that Fukushima Daiichi plant are facing significant amounts of pressure – and testing the very questions he was studying on paper more than three decades earlier. While he knew then that the Mark 1 had design limits, he said, no one knows now whether those limits will be surpassed.
Sure. That article adds some more information, but without the tech specs its kinda hard to make a judgement. As I said above the BWRs are closer, relatively to a danger area than the older 50s PWRs. I am not sure on the specific loss of coolant casualty that Bridenbaugh is refering to. There are several types of LOCCs, from very severe to merely troublesome. Engineers typically design for a worst case scenario. For instance the training prototype I worked with, they assumed a 8.0 earthquake plus catagory 5 hurricane (and resulting loss of all shore power/off site power), and a 17" asymeterical shear in the piping (basically a hole the size of the piping itself). That would be a VERY severe loss of coolant, and would subject the core to an immediate loss of all cooling and water. Thus the fuel elements would experience the maximum decay heat, with no cooling capacity, and would undergo meltdown at the fastest rate possible. The prototype has a whole separate pump/gravity drain system to deal with that, flooding the entire compartment with borated water to kill the plant (if for some reason the rods have failed to do so, perhaps due to thermal expansion), and then losses to ambient/discharge can keep the plant safe for days if not weeks.
In the case of the japanese plants, they were able to keep cooling capacity for at least 8 hours (and a bit more with the diesels before they were taken out by the Tsunami), when the decay heat was at its peak, so the thermal transients remaining are probably less than what Bridenbaugh was worried about, and also GE/TECO did address some of his concerns with refitting. So I would consider a meltdown + steam explosion to be unlikely. I am more concerned that they will mis-time the gradual releases of steam and hydrogen, and possibly ruin the relief valves, which would be similar to the Deepwater Horizon, especially if the valves are near the plant itself and thus inoperable due to radiation. That would result in a lot more radiation exposure o the public, and possibly a hydrogen explosion in the containment, if oxygen backflowed in.
Hopefully some of the NRC/AEC/IAEA folks are bringing in assistance, via whatever means necessary to restore as much cooling as possible. In any event, the affected plants are basically trashed now.
This is a very good explanation of what is probably going on, gets into the details of the chain of events that happen, and the safety features in such reactor designs, without getting too technical.
The real problem is that is nearly impossible to tell what and how bad the problem is through the layers of company management, japanese government, and the media.
I was just reading about this http://en.wikipedia.org/wiki/Thorium_fuel_cycle
http://www.acceleratingfuture.com/michael/blog/2006/10/a-nuclear-reactor-in-every-home/Thorium reactors will be cheap. The primary cost in nuclear reactors traditionally is the huge safety requirements. Regarding meltdown in a thorium reactor, Rubbia writes, “Both the EA and MF can be effectively protected against military diversions and exhibit an extreme robustness against any conceivable accident, always with benign consequences. In particular the [beta]-decay heat is comparable in both cases and such that it can be passively dissipated in the environment, thus eliminating the risks of “melt-down”. Thorium reactors can breed uranium-233, which can theoretically be used for nuclear weapons. However, denaturing thorium with its isotope, ionium, eliminates the proliferation threat.
I can barely wait for a free market in energy somewhere to see what structure of production would prove itself to be the best.
I don’t get why nuclear reactors need to have these insane safety requirements. Coal mines crush people all the time and nobody has a problem with that, not to mention that they spew filth into the air that kills tens of thousands every year. But nuclear reactors have to be 100% safe so nothing could conceivably happen. It’s an irrational overreaction. So far no nuclear reactor that wasn’t in a crazy communist country or on an earthquake fault had any serious accident.
It makes good press, mostly. ‘Nuclear Godzilla Destroys Tokyo’ type things. Add in general ignorance and simmer with a hefty dose of Ludditism, then season with politics to taste.