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Post by cyrilr on Jun 24, 2012 16:57:15 GMT 9.5
Actually, Sod, decommissioning a molted core reactor is very expensive. Three Mile Island cost a billion just to clean up, even though there was no land contamination at all. In today's money that would be over 1.5 billion per reactor. Bearing in mind that the meltdowns in Fukushima Daiichi units 1-3 were far more extensive than the partial meltdown of Three Mile Island. At TMI the damaged core didn't even get out of the reactor vessel, that's much easier to clean up. en.wikipedia.org/wiki/Three_Mile_Island_accidentThe 75 meltdowns claim is in chapter 6: "In most meltdowns the containment is expected to maintain its integrity for a long time, so the number of fatalities should be zero. In 1 out of 5 meltdowns there would be over 1,000 deaths, in 1 out of 100 there would be over 10,000 deaths, and in 1 out of 100,000 meltdowns, we would approach 50,000 deaths (the number we get each year from motor vehicle accidents). Considering all types, we expect an average of 400 fatalities per meltdown; the UCS estimate is 5,000. Since air pollution from coal burning is estimated to be causing 30,000 deaths each year in the United States (see Chapter 3), for nuclear power to be as dangerous as coal burning there would have to be 75 meltdowns per year (30,000 / 400 = 75), or 1 meltdown every 5 days somewhere in the United States, according to the RSS; according to UCS, there would have to be a meltdown every 2 months. Since there has never been a single meltdown, clearly we cannot expect one nearly that often." Interestingly we haven't any confirmed deaths from the radiation, but Cohen uses the linear no threshold model, a worst case scenario. It's kind of funny how that still makes nuclear so much better than anything else (especially coal).
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Post by cyrilr on Jun 23, 2012 23:08:12 GMT 9.5
I should add also, that inferring anything statistical from Fukushima Daiichi meltdowns is of course impossible - most of the meltdowns in commercial plants in history were at Daiichi!! Anyone who has taken a class in statistics means we shouldn't try to infer any probabilities out of such limited statistics. Cohen does make an interesting calculation though, which shows that, for nuclear power to be as dangerous as coal, there would have to be 75 meltdowns per year.
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Post by cyrilr on Jun 23, 2012 23:03:26 GMT 9.5
Well, the Cohen book is among the best and most scientific that I've read so far, covering most subjects in a scientific and quantitative way. The Fukushima meltdowns would be in the range of the 1 in 10 meltdowns, ie very serious, when compensating for the 3 meltdowns (factor 3) and inflation (factor 2-3), it becomes a 1 to 1.5 billion per reactor cost.
However, there are some peculiar things about the probabilistic analysis that you have to know. The probabilistic analysis is done with internal failure probabilities, which determine Cohen's cost range. The probabilistic analysis usually does not treat common mode failure from flooding (tsunami) in a generic way, as this is of course site dependent. In stead it is often asserted that design basis takes care of flooding, ie by having sufficient elevation etc. which is simple and therefore assumed to be incorporated into the risk analysis of the site. Clearly this went wrong in the design of the Daiichi plants 1 to 4. So it's a bit not entirely an apples to apples comparison. Fukushima accident wasn't an internal equipment event, it was common mode failure.
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Post by cyrilr on Jun 23, 2012 18:37:36 GMT 9.5
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Post by cyrilr on Jun 22, 2012 2:01:03 GMT 9.5
This is another silly argument not well thought through by the anti-nukes.
It is not hard to build cooling towers if necessary. We're talking decades long times to decide what to do.
It is also not hard to add more seawater pumps to do more water flow for once through cooling. This means you get the same water temperature discharge. The hidden notion is apparently that we can't add a few more pumps to nuclear plants. Which is absurd. It shows how poorly devised the anti nuclear/nuclear hyperbole arguments are.
Decades is a long time to do anything, such as building dikes. I live in the Netherlands, below seawater level. It is not hard for us to add height and weight to the dikes and engineered protections. The only nuclear plant we have can take a much higher level of seawater rise than the worst case IPCC scenarios of 2080.
The problem will not be with nuclear plants. It will be with poor countries that can't afford expensive dikes and engineered seawalls. Such as Bangladesh. But no one cares about Bangladesh because Bangladesh has no nuclear plants.
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Post by cyrilr on Jun 21, 2012 23:34:02 GMT 9.5
Almost all energy is used in a centralized manner. The world is increasingly urbanizing.
Remote solar is useful, but not important in terms of CO2 emissions. Only a tiny fraction of global electricity is generated by remote diesel generators. It's a good market for PV to develop in, as it should be doing if it weren't for distorting subsidies in grid connected PV in Germany which is cloudy and has lots of cheap reliable coal (ie no economic case ever).
As for centralized CSP with heat storage. Technically there's a major problem, as most areas, even deserts, have large winter low solar production. A day of heat storage won't deal with that. If the industries must choose between shutting down in winter or burning fossil fuels, we can all see what will happen.
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Post by cyrilr on Jun 19, 2012 1:19:29 GMT 9.5
So Philip provides a source for the water makeup, but this source does not in any way substantiate how a few watts per meter of rod worth of decay power is supposed to overheat the fuel, much less how this is going to harm people in Tokyo. I happen to know how that is supposed to be possible: ignoring the water rods and assuming adiabatic heatup. Gee whiz. I'd like to live in an adiabatic world. I could run naked in the street and not get cold. It's kind of funny to use such assumptions for accident analysis. Kind of like, let's assume that gravity suddenly stops, causing the water in the spent fuel to float out of it, overheating the fuel. Gee whiz. Also, Philip: there's no such thing as a worst case scenario. As Cohen showed, the worst case scenario is that a gasoline fire ends up putting entire cities to ashes, killing millions. www.phyast.pitt.edu/~blc/book/But if you must violate the laws of thermodynamics such as assuming adiabatic heatup on a structure that resembles my home radiator (deus ex machina) to get to it, nuclear power is clearly very safe.
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Post by cyrilr on Jun 18, 2012 18:03:26 GMT 9.5
A quick response to a couple of misunderstandings in Geoff Russell's response to my comment. Secondly, in the early stages of the accident the chairman of the Atomic Energy Commission produced an estimate of the implications of a worst case scenario. This was based on the assumption that the fuel assemblies in the spent fuel pool of unit 4 were exposed for a prolonged period of time. His estimate was that a region extending almost to Tokyo would have to be evacuated, based on Chernobyl principles. Even if you choose to reject Chernobyl principles the amount of radioactive material released would have been massive, dwarfing the releases from Chernobyl. The Chairman is a known anti-nuke scaremongerer. There was never any risk in a 50 mile radius. Chernobyl evacuation criterion was 1 mSv/year. Much less than average global background, and a hundred times less than some places like the beaches in Brazil (lots of tourists go to the radioactive beaches, oddly). This is, by no standard, a reasonable evacuation, as billions of people living in slightly higher than normal background radiation would have to be evacuated. I do agree though that Tokyo should have been evacuated, the particulate matter from fossil fuel combustion is substantially more dangerous than anywhere in Fukushima. More than 10 million are at risk and thousands die prematurely each year due to this contiuous fossil fuel disaster. Wrong. Heatup is non-adiabatic. I'm familiar with the NRC estimates, which assume adiabatic heatup. The spent fuel pools are open to air which is about as adiabatic as a bonfire. If you make silly assumptions that violate the laws of thermodynamics, I can get my body to overheat to a billion degrees as well. Spent fuel rods in the nr. 4 spent fuel produced about the amount of heat of a standard office fluorescent lightbulb. How many office fluorescent tubes have you seen melting down? Wrong again. The fundamental principle of an evacuation is to evacuate when staying is very likely a much more dangerous situation than evacuation. Since evacuation kills a lot of people by definition, the decision to evacuate was a wrong decision. Add the fearmongering deaths, likely ranging in the thousands of abortions, alcoholism, etc. and the evacuation is clearly murder to the first degree. Since we are not evacuating polluted Tokyo, it makes no sense to evacuate Fukushima. Moving Tokyo residents to Fukushima would save many lives.
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Post by cyrilr on Jun 18, 2012 16:50:58 GMT 9.5
I should add that it isn't just the silly journalists and activist organisations that are spreading wild fear stories. The nuclear regulator and industrial agencies are helping along with their share of fearmongering, ballooning microsieverts up with massive scare stories. Here are just some examples of the extreme fearmongering induced by the japan regulator, who should be doing the opposite. energyfromthorium.com/forum/viewtopic.php?f=12&t=3453The fearmongering is clearly so pervasive, I don't know how to stop it. If even the japan industrial forum decides that fearmongering over microsieverts makes sense, the political situation in japan looks terrible.
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Post by cyrilr on Jun 18, 2012 16:45:16 GMT 9.5
1) However the argument in this article overlooks a few important points. The first is that it would have been a different story if people had not evacuated and given up hope of living in a large swathe of land for decades or more. The doses would have been greater and possibly more accurately measurable had everyone just stayed there. Arguments such as the one in this article completely overlook this huge impact on people's lives. 3) Of course, evacuation itself has major effects on people's health, in particular their psychological well being. To imply that cancer is the only thing that matters is grossly misleading According to Asahi Shimbun, there are at least 163 disaster related deaths attributable directly to the evacuation and the miserable conditions that followed from it: www.asahi.com/english/TKY201110170370.htmlThis is just the start. If Chernobyl is any indication, several hundred thousand abortions are the next big risk, and thousands of causes of depression and alcoholism etc. aren't going to help the death toll. I very much doubt that no evacuation at all would have killed even 163 people. And that would be with theoretical models, whereas the 163 deaths from the evacuation are real people. Just like the thousands of coal miners that die each year are real people.
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Post by cyrilr on Jun 16, 2012 20:42:03 GMT 9.5
thanks for those graphs, cool work! i think it is obvious that solar will have little effect on winter peaks and basically none on night time. but the topic of this post is: "Solar power correlating with peak demand - a myth?" and this can be definitely answered: in Germany, the correlation is close to perfect in summer. Such an answer would be disingenious at best, as Germany's demand peaks in winter, not in summer. As such it is very much ANTI-correlated with demand. In the future with heat pumps providing winter heating (to eliminate natural gas and oil heating systems) this anti-correlation will be further enforced.
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Post by cyrilr on Jun 16, 2012 20:36:32 GMT 9.5
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Post by cyrilr on Jun 14, 2012 21:48:38 GMT 9.5
I'm not really sure if the small modular reactors are in the right size category for remote powering. Here's one remote power plant supplier that has power plants from 0.165 to 10 MWe. www.ergon.com.au/community--and--our-network/network-management-and-projects/isolated-and-remote-power-stationsMuch smaller than the smallest, 25 MWe small modular reactor. A remote industrial or mining company would be more suitable in power needs, and would be less frightened of nuclear reactors (something tells me that remote Australian communities will not like nuclear reactors of any type in their backyards). It is to be hoped that some niches can be established for small modular reactors. I should add the NuScale design to the list of small modular reactors. They have a particularly simple and elegant solution to the decay heat cooling problem. www.nuscalepower.com/
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Post by cyrilr on Jun 14, 2012 17:56:59 GMT 9.5
There certainly look to be many advantages to be had with small modular design. Yet there are some things I worry about. If we look at historic reactor developments, we see that all the major passive reactor designs have evolved from medium size (600-700 MWe) to much larger sizes (1200-1600 MWe). This happened with Westinghouse's AP600 project, that got upgraded to the AP1000 due to economic reasons (according to Westinghouse). It happened with AECL's ACR700, which was deemed to small to be economic, and was upgraded to the ACR1000 project. It happened with GE's SBWR which got upgraded to about twice its initial capacity in the ESBWR successor.
All of the major vendors have unanimously found their smaller advanced reactors uneconomical. That has me worried. Specifically, reactors have a large scaling factor, that is, reactors are cheaper per Watt for bigger sizes. Smaller reactors also need more fissile material to start up, further increasing their costs and making large scale deployment more difficult.
Sure, with sufficient production the small modular reactors could have a faster learning curve. But who's going to buy the initial units which will be very expensive?
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