Lessons from Dai-ichi

Last Saturday, I began to form the opinion that one or more of the Dai-ichi reactor cores had experienced a partial melt down. I was by no means sure of this view because it assumed that the explosion had been a hydrogen explosion. My study of reports concerning the Three Mile Island accident had led me to speculate, that if the explosion had been a hydrogen explosion, the most likely source of the hydrogen was a chemical reaction between coolant water, and overheated core materials. I assumed that some core water might have boiled off, uncovered, uncovering the upper part of the core, which then overheated to the extent that it would begin to melt.

When Japanese technicians injected water into the reactor, it came in contact with the partially melted core, and a chemical reaction between Zirconium in the reactor fuel cladding and the oxygen in water molecules, had released hydrogen in the core. The Japanese technicians had vented the hydrogen from the core, and it vented along with hot steam, and then exploded when it recombined with oxygen in the air. This assumption indicated that the Dai-ichi crisis was at least as bad as Three Mile Island, if not worse. The Japanese, given my speculation, would have sacrificed parts of the reactor building, in order to protect the steel containment vessel from rupture caused by excessive gas pressure.

The reality of at least a partial core meltdown in Dai-ichi 1, 2, and 3 could explained by the release of radioactive gases from fuel pellets. When the core was subsequently vented, the release of the radioactive fission product gasses would explain why many spikes of radiation during the Dai-ichi event have occurred. The radioactive gasses, likely to be encountered during a core meltdown are not very dangerous in practice. They are noble gases, very radioactive but chemically inactive. They are dispersed by natural process in air, and very quickly become so diluted, that they pose no danger to human beings. Since noble gases do not form chemical bonds, they do not linger in the human body, thus do not pose health risks. When scientist looked at the human health consequences of the Three Mile Island accident, the realized that the radiation level of air down wind from Three Mile Island was simply not high enough to cause cancer and other radiation related illnesses.

In addition to radioactive gases, some easily vaporized radioisotopes were released by the Three Mile Island accident. Of these Iodine-131 is the most dangerous. Unlike the noble gases, Iodine-131 does form chemical bonds, is solid rather than gaseous at ordinary temperatures, and likely to enter the human body from the food chain. Iodine-131 forms volatile chemical compounds, that vaporize at high temperatures. Iodine-131 does stick around, but only for a short while. It has a half life of a little more than 8 days. Thus if people can be kept out of contact with Iodine-131 for a couple of months it ceases to be dangerous. In addition potassium iodine tablets offer some protection against iodine-131 forming chemical bonds with body tissues.

Three other potentially dangerous radioisotope are in danger of escaping a reactor core during a reactor accident. They are:

Sr-90
Cs-137
Cs-134

We ar talking about some very nasty stuff here, the stuff that keeps people out of the Chernobyl exclusion zones for nearly 25 years. Fortunately not much of these undesirables escaped during the Three Mile Island accident, so the good citizens of Pennsylvania were able to return to their homes. The difference between TMI and Chernobyl was that inChernobyl the core exploded, destroying all containment, and then caught on fire, and quickly began discharging copious amounts of volatile fission products

What the Japanese tecnicians appear to be doing at Dai-ichi is struggling to prevent the sort of fire that would release large amounts of volatile fission products. There has bee some release. How do we know this? Because when an NBC news man came back from Dai-ichi, he had radioactive material on his shoes. Not a lot, but too much to be tracking around.

The same story suggests that maybe not a lot of volatile fission products have escaped yet, just enough to be picked up on the shoes, by newspeople walking on soil that has been lightly dusted with radio-iodine and other nasties., but not at a level yet to be really dangerous.

It is now fairly clear that that some level of meltdown has happened, but that we are not yet at the China Syndrome by any means, but yesterday Nuclear Regulatory Commission Chairman Gregory Jaczko said,

We believe that secondary containment has been destroyed and there is no water in the spent fuel pool and we believe that radiation levels are extremely high which could possibly impact the ability to take corrective measures.

Is not clear that all of the water in the spent fuel pool is gone, but Jaczko's fears may not be entirely unjustified.

The New York Times has quoted a spokesman for Japan’s Nuclear and Industrial Safety Agency, Yoshitaka Nagayama, as saying,

Because we have been unable to go the scene, we cannot confirm whether there is water left or not in the spent fuel pool at Reactor No. 4.

If the Japanese don't know, how can Jaczko? The answer might be computer accident simulation. I don't know if such a simulation exists, but if Jaczko was not being irresponsible, he needed to be able to point to some back up to his assessment.

There are still dangers here, the crisis is my no means over, but the decay of fission products is already begin to slow down, and with it both the radiation and the heat that that decay produces. While it is too soon to imagine that the crisis is over, the fact that the first week of the crisis has passed is a signal that the hope that a disaster will be prevented is fully justified. We cannot be sure that the worst is over, but the odds are beginning to move in that direction.

Nuclear power will survive the events in Dai-ichi. This accident will be studied for some time to come for lessons about nuclear safety. The first lesson, and this is obvious, is to assume that the worst earthquake or tsunami ever recorded for an area is possible again, and build accordingly. The Dai-ichi reactor complex was not designed to withstand a 10 meter plus tsunami, while it probably should have been built to withstand at least a 10 meter tsunami. Earlem College Geologist Wesley Nutter found evidence in 2009 that 10 meter (or even higher) waves had repeatedly pounded the coast of northern Japan over the last 3000 years. The geological record suggests that the tsunami of 2011 was a once in every 500 year event. For most people, once in every 500 years is never. Americans have built the cities of Memphis and St. Louis in a zone in which evidence suggests episodes of multiple great earthquakes - up to magnitude 8 - occure every five hundred years or so. Should people live, let alone build reactors in such a dangerous area? Should people live, let alone build reactors in Japan, California, or anywhere eles along the 24,000 mile Pacific ring of fire?

The second lesson has to do with reactor design. Some new reactors, most particularly the the Westinghouse AP-1000, and the GE ESBWR feature gravity powered emgency water tanks above the reactor core. In the future, reactors designs may be subject to the Dai-ichi test. Could the reactor design survive the Dai-ichi event without core melt down. In the case of the AP-1000 the answer is possibly yes, while in the case of the ESBWR he answer is very likely yes. The ESBWR design sets the new bar for reactor safety, and that bar his high.

A third lesson is that the Dai-ichi demonstrated an impressive seismic performance. They survive an earthquake of a far greater magnitude than they were designed too. No doubt this seismic performance will be the subject of further research.

A fourth lesson is that reactor safety design, should include a method of mitigating any China syndrome incident, in the event of a emergency coolant failure. Devices such as steam explosion proof core catchers will be researched,and perhaps modifications to existing reactor designs considered.

A fifth set of lessons, as of yet largely undefined, will come about as the result of studying what actually happened inside the cores of Dai-ichi reactors.

Finally, I would argue, that the day of the Light Water Reactor is drawing to a close. Several Generation IV reactor technologies would have survived the Dai-ichi incident without a serious incident. These include Pebble Bed Modular Reactors, and Molten Salt Reactors. In the case of Molten Salt Reactor Technology, the safety technology appears to be consistent with lowering nuclear costs. The PBMR can be shudown without core melting, while if a MSR begins to overheat, a plug will automatically melt and the reactor core will drain into a series of tanks that uses a well understood simple and natural technology, the chimny effect, to keep the fuel cool.

I have, in Nuclear Green, repeatedly pointed to the issue of nuclear safety, and the need to develop radical high safety nuclear technology. It is not that reactors are unsafe, but rather that safer reactors are possible without increasing nuclear costs, and we ought to build the safest reactors possible, within our financial limits. Not only are safer reactors possible, but they will be superior to Light Water Reactors in many other respects, including the long term sustainability of their fuel sources, and their scalability. If the Dai-ichi crisis fails to teach us the importance of moving forward on the implementation of a more advanced and safer nuclear technology, it would be a tragedy.

The argument for factory assembly of the LFTR

David Walters and I have a standing disagreement about factory production. of LFTRs. My case study was based on the auto industry which some early manufacturers built assembly kits and then when they received an order they dispatched a kit and an assembly team to the customer. The cars were assembled near the customer's home. This is still the prevailing system of reactor manufacture. Eventually the car companies built all of their cars in factories but with an assembly team approach. People would typically have a number of assembly assignments on each car. The car was built at a fixed location and the workers flowed around the car as they manufactured it. When Henry Ford set up his assembly line workers had only one assignment, and one work station. In the Ford factory the cars flowed from worker to worker. Note that all of the Ford assembly was still hand assembly. The great advantage of the Ford assembly line was in the greater devision of labor and the more efficient use of labor. It was the division of labor and the flow of manufactured objects from worker to worker o the assembly line that revolutionized auto industry productivity.

The effect of the division of labor on worker productivity is the subject of a marvelous passage from Adam Smith's "Wealth of Nations".

To take an example, therefore, from a very trifling manufacture; but one in which the division of labour has been very often taken notice of, the trade of the pin-maker; a workman not educated to this business (which the division of labour has rendered a distinct trade), nor acquainted with the use of the machinery employed in it (to the invention of which the same division of labour has probably given occasion), could scarce, perhaps, with his utmost industry, make one pin in a day, and certainly could not make twenty. But in the way in which this business is now carried on, not only the whole work is a peculiar trade, but it is divided into a number of branches, of which the greater part are likewise peculiar trades. One man draws out the wire, another straights it, a third cuts it, a fourth points it, a fifth grinds it at the top for receiving the head; to make the head requires two or three distinct operations; to put it on, is a peculiar business, to whiten the pins is another; it is even a trade by itself to put them into the paper; and the important business of making a pin is, in this manner, divided into about eighteen distinct operations, which, in some manufactories, are all performed by distinct hands, though in others the same man will sometimes perform two or three of them. I have seen a small manufactory of this kind where ten men only were employed, and where some of them consequently performed two or three distinct operations. But though they were very poor, and therefore but indifferently accommodated with the necessary machinery, they could, when they exerted themselves, make among them about twelve pounds of pins in a day. There are in a pound upwards of four thousand pins of a middling size. Those ten persons, therefore, could make among them upwards of forty-eight thousand pins in a day. Each person, therefore, making a tenth part of forty-eight thousand pins, might be considered as making four thousand eight hundred pins in a day. But if they had all wrought separately and independently, and without any of them having been educated to this peculiar business, they certainly could not each of them have made twenty, perhaps not one pin in a day; that is, certainly, not the two hundred and fortieth, perhaps not the four thousand eight hundredth part of what they are at present capable of performing, in consequence of a proper division and combination of their different operations.

I know that it will pain David no end to read Adam Smith rather than Karl Marx, but it will do him no end of good in the end.

Smith understood that the organization of labor and the assignment of simple tasks that was to key to labor productivity. Westinghouse estimates that it will take between sixteen to twenty million man hours of labor tbuild an AP-1000. It becomes a monumental task just to organize the flow of work on the construction site. Teams of managers will inevitably be involved in the relaying of information between project engineers, and workers. Workers are highly skilled, and flow from project to project on the construction site. The organization of the work is constantly in danger of breakdown, and the learning curve progresses slowly, because it takes years to manufacture one reactor.

If reactors are manufactured in factories then they must be transportable. Hence must be built in small transportable units. LFTRs need not be horrendously complex. Controls are largely passive. hence there are no control rods. There is no complex system of pipes inside the reactor. Conditions - reactivity and heat levels - inside the core of a LWR are far from uniform, hence the need instrumentation and localized control. Conditions in the LFTR core are homogeneous. There is no need for refined instrumentation and refined control systems. LWRs have complex pipe systems, that are required inorder to bring coolant water to every part of the reactor. In addition to the primary coolant system, there are complex secondary systems and an emergancy cooling system.

We thus have a much simpler assembly task for our Liquid Fluorid Thorium Reactor (LFTR) factory workers, compared with the AP-1000 construction crew. The next question is how many LFTRs will we need? The DOE estimates that in order to provide for estimated peak demand in 2050, the United States will need something like 1800 GWs of electrical generating capacity. Perhaps 300 GWs will be LWR base load reactors. The rest is at the moment an open question, but 15,000 factory built LFTRs are not out of the question. This number may be conservative, because we may be expanding our generating capacity to generate electricity for transportation, for space heating that is now acomplished by natural gas. There are other markets, for example process heat. LFTRs could be used to power ships. There is a potential for a large export market. Consider that even with proliferation restraints, the export market could be 10 times larger than in the United States.

A highly automated assembly line might make sense.

Workers on a modern auto assembly line

Chinese AP-1000 contractors

More information is emerging about contracts related to the construction of the first four Chinese AP-1000s.   Of particular note is the role of a Korean company Doosan Heavy Industries which is building both the reactor pressure vessels and the steam generators for the first four Chinese AP-1000s. The Doosan components of the AP-1000 reactor kit appear to be running between $175 million and $144 Million, with perhaps some price drop as serial production of AP-1000 components begins.

I suspect that China plans to add the heavy industrial capacity to build pressure vessels and steam generators in the not too distant future. It was already known that Curtiss-Wright will build the coolant pumps for the first batch of AP-1000s. Curtiss-Wright recently received purchase orders for 24 AP1000 coolant pumps for over $300 million. This would mean a price of at least $100 million per reactor for coolant pumps. Serial production of pumps by Curtiss-Wright would probably lower per unit costs.

Curtiss-Wright can expect another order for 8 more pumps n the near future, and probably for dozens and even hundreds more during the next few years. Steam turbines for Chinese AP-1000 will come from Mitsubishi Heavy Industries and its Chinese partner Harbin Power Equipment. We could probably expect that Harbin Power Equipment will be producing a large number and perhaps all of the stram turbines fir Chinese AP-1000s.

The Second Nuclear Age Begins

The initiation of the construction of the first ever Westinghouse AP-1000 reactor in Sanmen City, Zhejiang Province, China today, the curtain was run up on the second nuclear age. Three more AP-1000 are on order in China. TVA has applied for a NRC license to build and operate two AP-1000's and several other prospective operators plan to apply for licenses for over a dozen more AP-1000s this year. In addition to the 4 AP-1000's on order, China has indicated that it intends to make the AP-1000 the center of its plan to develop nuclear powered electrical sources.

Photo taken on Feb. 26, 2008 shows the construction of China's first third-generation nuclear plant and also the world's first AP1000 nuclear plant, the AP1000 Sanmen nuclear plant, in Sanmen, east China's Zhejiang Province. The Sammen Nuclear Power Project kicked off its excavation construction on Tuesday. (Xinhua Photo)

Photo taken on Feb. 26, 2008 shows the excavation kick-off ceremony of the AP1000 Sammen Nuclear Power Project, in Sanmen, east China's Zhejiang Province. The AP1000 Sanmen nuclear plant, China's first third-generation nuclear plant, would also become the world's first AP1000 nuclear plant.(Xinhua Photo)

Construction of the AP-1000 is expected to be take as little as 36 months. Because the NRC licensing of TVA's initial reactors is expected to take 42 months, the construction of America's first AP-1000 is expected to commence in 2012. The first TVA AP-1000, located at TVA’s Bellefonte, Alabama nuclear site s is expected to be completed about 2015, followed by a second reactor being completed in 2o17. In addition TVA expects to complete the construction of another reactor at the Watts Bar, Tennessee nuclear plant in 2012.

The AP-1000 is rated from 1100 to 1250 MWs. AP-1000 generated electricity is expected to costs below 3.5 cents per KWh, and AP-1000s ae expected to opeate for 60 year. TVA is the lead licenses applicant for the AP-1000. The numerous other applications for the construction of AP-1000s in the United States will be based on the approval of the TVA application,

TVA is the only national utilirty to have continued building reactors during the last 2o years. The first Watts Bar reactor, begun in 1972 was completed in 1996. Following the completion of the Watts Bar reactor, TVA undertook to rebuild the Browns Ferry Unit 1 reactor, damaged by a fire in 1975. That reactor was rebuilt beginning in 2002, and emerged as a virtually new unit, in 2007. Both reactors are currently contributing power to the TVA system. In addition, TVA began a program to complete a second Watts Bar reactor in late 2007. Construction of the reactor had begun in the 1970's and had been suspended early in 1985. Construction on the second Watts Bar reactor is expected to be completed in 2012. Because TVA has recent experience with reactor construcion, it was considered a good candidate to lead off the construction of Westinghouse's recently designed AP-1000.

In 2012 when construction of TVA's first AP-1000 begins, Westinghouse anticipates that it will have broungt its first AP-1000 project in China to a sucessful completion, while TVA will have completed the construction of 2 reactors in the five previous years. By 2017 TVA anticipates the completion of its 4th reactor in a decade. By that time no doubt, TVA will have more nuclear projects on the drawing board.

Westinghouse gets new AP-1000 order from China

From: International Herald Tribune
Westinghouse reactor to power China plant
By Winnie Zhu
Bloomberg News
Wednesday, December 5, 2007

SHANGHAI: China Guodian, one of the five biggest electricity generators in the nation, plans to build a nuclear power station in Fujian, southeastern China, using technology from the Westinghouse Electric unit of Toshiba.

The plant in Zhangzhou city will have "several" reactors with one million-kilowatt capacity each and use the Westinghouse AP1000 technology, according to a statement Tuesday on the State-owned Assets Supervision and Administration Commission's Web site. No financial details were given.

Westinghouse and Areva of France are competing to build as many as 26 reactors by 2020 as China turns to atomic energy to cut pollution and reliance on oil. The nation needs to build two reactors a year to meet a target of generating 4 percent of its power supply from nuclear plants by 2020.

"Westinghouse has its advantages in terms of technology and reactors operation," Yao Wei, an analyst at Guotai Jun'an Securities in Shanghai, said Wednesday. "It has a good relationship with Chinese partners."

Liu Kemou, a director at China Guodian's media department, confirmed the statement, but declined to comment further. Wen Xuting, the company's spokesman, could not be reached.

Toshiba shares closed at ¥883, or $7.99, after rising 2.08 percent in Tokyo. GD Power Development, the Shanghai-listed unit of China Guodian, climbed 4.73 percent, the biggest daily gain since Nov. 6, to close at 15.93 yuan, or $2.15.

Kaori Hiraki, a spokeswoman for Toshiba, could not be reached for comment.

Westinghouse secured a $5.3 billion order from China National Nuclear in July to provide four AP1000 nuclear power reactors in Haiyang, Shandong Province and Sanmen, Zhejiang Province, both in eastern China.

Westinghouse will start building the reactors in eastern China in 2009. The first reactor will begin operation in late 2013 and the remaining three will start up between 2014 and 2015, it said on July 24.

The company expects at least 35 orders within the next decade as the United States and China expand atomic energy, Dan Lipman, the company's senior vice president, said Sept. 19.

Areva in November won an €8 billion, or $12 billion, agreement to build two nuclear reactors for China Guangdong Nuclear Power in Taishan in southern Guangdong Province, the company's chief executive officer, Anne Lauvergeon, said in Beijing on Nov. 26.

Guangdong Nuclear, the second-largest nuclear power producer in the country, will also gain access to 35 percent of production from Areva uranium unit UraMin, Lauvergeon said. The French company will supply nuclear fuel for the two reactors with 1,700 megawatts capacity each until 2026, she said then.

China plans to increase its spending on nuclear power plants by 12.5 percent to 450 billion yuan, or $61 billion, during the 15 years ending in 2020, the National Development and Reform Commission, the top economic planner in the nation, said Nov. 2.