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D'coda Dcoda

Scientists Radically Raise Estimates of Fukushima Fallout [25Oct11] - 0 views

www.nature.com/...478435a.html

shared by D'coda Dcoda on 26 Oct 11 - No Cached
  • The disaster at the Fukushima Daiichi nuclear plant in March released far more radiation than the Japanese government has claimed. So concludes a study1 that combines radioactivity data from across the globe to estimate the scale and fate of emissions from the shattered plant. The study also suggests that, contrary to government claims, pools used to store spent nuclear fuel played a significant part in the release of the long-lived environmental contaminant caesium-137, which could have been prevented by prompt action. The analysis has been posted online for open peer review by the journal Atmospheric Chemistry and Physics.
  • Andreas Stohl, an atmospheric scientist with the Norwegian Institute for Air Research in Kjeller, who led the research, believes that the analysis is the most comprehensive effort yet to understand how much radiation was released from Fukushima Daiichi. "It's a very valuable contribution," says Lars-Erik De Geer, an atmospheric modeller with the Swedish Defense Research Agency in Stockholm, who was not involved with the study. The reconstruction relies on data from dozens of radiation monitoring stations in Japan and around the world. Many are part of a global network to watch for tests of nuclear weapons that is run by the Comprehensive Nuclear-Test-Ban Treaty Organization in Vienna. The scientists added data from independent stations in Canada, Japan and Europe, and then combined those with large European and American caches of global meteorological data.
  • Stohl cautions that the resulting model is far from perfect. Measurements were scarce in the immediate aftermath of the Fukushima accident, and some monitoring posts were too contaminated by radioactivity to provide reliable data. More importantly, exactly what happened inside the reactors — a crucial part of understanding what they emitted — remains a mystery that may never be solved. "If you look at the estimates for Chernobyl, you still have a large uncertainty 25 years later," says Stohl. Nevertheless, the study provides a sweeping view of the accident. "They really took a global view and used all the data available," says De Geer.
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  • Challenging numbers Japanese investigators had already developed a detailed timeline of events following the 11 March earthquake that precipitated the disaster. Hours after the quake rocked the six reactors at Fukushima Daiichi, the tsunami arrived, knocking out crucial diesel back-up generators designed to cool the reactors in an emergency. Within days, the three reactors operating at the time of the accident overheated and released hydrogen gas, leading to massive explosions. Radioactive fuel recently removed from a fourth reactor was being held in a storage pool at the time of the quake, and on 14 March the pool overheated, possibly sparking fires in the building over the next few days.
  • But accounting for the radiation that came from the plants has proved much harder than reconstructing this chain of events. The latest report from the Japanese government, published in June, says that the plant released 1.5 × 1016 bequerels of caesium-137, an isotope with a 30-year half-life that is responsible for most of the long-term contamination from the plant2. A far larger amount of xenon-133, 1.1 × 1019 Bq, was released, according to official government estimates.
  • The new study challenges those numbers. On the basis of its reconstructions, the team claims that the accident released around 1.7 × 1019 Bq of xenon-133, greater than the estimated total radioactive release of 1.4 × 1019 Bq from Chernobyl. The fact that three reactors exploded in the Fukushima accident accounts for the huge xenon tally, says De Geer. Xenon-133 does not pose serious health risks because it is not absorbed by the body or the environment. Caesium-137 fallout, however, is a much greater concern because it will linger in the environment for decades. The new model shows that Fukushima released 3.5 × 1016 Bq caesium-137, roughly twice the official government figure, and half the release from Chernobyl. The higher number is obviously worrying, says De Geer, although ongoing ground surveys are the only way to truly establish the public-health risk.
  • Stohl believes that the discrepancy between the team's results and those of the Japanese government can be partly explained by the larger data set used. Japanese estimates rely primarily on data from monitoring posts inside Japan3, which never recorded the large quantities of radioactivity that blew out over the Pacific Ocean, and eventually reached North America and Europe. "Taking account of the radiation that has drifted out to the Pacific is essential for getting a real picture of the size and character of the accident," says Tomoya Yamauchi, a radiation physicist at Kobe University who has been measuring radioisotope contamination in soil around Fukushima. Click for full imageStohl adds that he is sympathetic to the Japanese teams responsible for the official estimate. "They wanted to get something out quickly," he says. The differences between the two studies may seem large, notes Yukio Hayakawa, a volcanologist at Gunma University who has also modelled the accident, but uncertainties in the models mean that the estimates are actually quite similar.
  • The new analysis also claims that the spent fuel being stored in the unit 4 pool emitted copious quantities of caesium-137. Japanese officials have maintained that virtually no radioactivity leaked from the pool. Yet Stohl's model clearly shows that dousing the pool with water caused the plant's caesium-137 emissions to drop markedly (see 'Radiation crisis'). The finding implies that much of the fallout could have been prevented by flooding the pool earlier. The Japanese authorities continue to maintain that the spent fuel was not a significant source of contamination, because the pool itself did not seem to suffer major damage. "I think the release from unit 4 is not important," says Masamichi Chino, a scientist with the Japanese Atomic Energy Authority in Ibaraki, who helped to develop the Japanese official estimate. But De Geer says the new analysis implicating the fuel pool "looks convincing".

  • The latest analysis also presents evidence that xenon-133 began to vent from Fukushima Daiichi immediately after the quake, and before the tsunami swamped the area. This implies that even without the devastating flood, the earthquake alone was sufficient to cause damage at the plant.

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    The Japanese government's report has already acknowledged that the shaking at Fukushima Daiichi exceeded the plant's design specifications. Anti-nuclear activists have long been concerned that the government has failed to adequately address geological hazards when licensing nuclear plants (see Nature 448, 392–393; 2007), and the whiff of xenon could prompt a major rethink of reactor safety assessments, says Yamauchi.

  • The model also shows that the accident could easily have had a much more devastating impact on the people of Tokyo. In the first days after the accident the wind was blowing out to sea, but on the afternoon of 14 March it turned back towards shore, bringing clouds of radioactive caesium-137 over a huge swathe of the country (see 'Radioisotope reconstruction'). Where precipitation fell, along the country's central mountain ranges and to the northwest of the plant, higher levels of radioactivity were later recorded in the soil; thankfully, the capital and other densely populated areas had dry weather. "There was a period when quite a high concentration went over Tokyo, but it didn't rain," says Stohl. "It could have been much worse." 
D'coda Dcoda

NextEra revises dates to boost Fla. nuclear output[25Oct11] - 0 views

www.reuters.com/...-florida-idUSN1E79O29H20111026

shared by D'coda Dcoda on 26 Oct 11 - No Cached
  • Florida Power & Light, a unit of NextEra Energy Inc , plans to complete work to increase the output at its 839-megawatt St. Lucie 1 nuclear reactor during an extended refueling outage set to begin next month, according to a state regulatory filing.The work is part of FP&L's larger effort, known as a nuclear "uprate," to add 450 MW in capacity at four existing reactors at the Turkey Point and St. Lucie stations by 2013.FP&L, the state's largest electric utility, recently adjusted some of the outage dates to minimize an overlap between the planned nuclear outages and non-nuclear outages, utility officials said.Adding the 450 MW is now estimated to cost $2.48 billion, the company said, compared with FP&L's initial 2007 estimate of $1.5 billion for an increase of 400 MW.
  • The increased output will supply 209,000 customers, save $4.8 billion in fuel costs over the project's lifetime and cut carbon dioxide emissions in the state, said NextEra spokesman Michael Waldron.On Monday, the Florida Public Service Commission approved FP&L's request to recover about $196 million from customers next year for the uprate costs, as well as costs to develop two new reactors at Turkey Point expected to begin service in 2022-2023."The vast majority of our request -- about 90 percent -- is dedicated to the uprate project," Waldron said.In the filing, FP&L said it plans to shut St. Lucie 1 on Nov. 26 to perform work to increase its output by 122 MW. The outage is expected to last 110 days, or until mid-to-late February.
  • On Feb. 6, 2012, FP&L plans to shut the 693-MW Turkey Point 3 reactor for 120 days to boost that unit's output by 109 MW, the utility said in the filing.St. Lucie 2, also rated at 893 MW, is set to shut June 27, 2012, for 95 days for uprate work. The unit was shut for an extended period earlier this year for work that increased output by 29 MW due to a more efficient low-pressure rotor, the filing said.The extra 29 MW is helping to save $1 million per month in fuel costs, Waldron said.Next fall, the 693-MW Turkey Point 4 reactor is scheduled to shut Oct. 1 for 120 days for work to increase output by 109 MW, FP&L told state regulators.
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  • To increase the output of reactors, operators install new pipes, valves and pumps, along with heat exchangers, new electric transformers, turbines and generators.The U.S. Nuclear Regulatory Commission is currently reviewing FP&L's uprate applications, which were filed in 2010 and early 2011.
D'coda Dcoda

Florida approves 2012 FPL, Progress nuclear charges [25Oct11] - 0 views

www.reuters.com/...-florida-idUSN1E79N1ZV20111024

shared by D'coda Dcoda on 26 Oct 11 - No Cached
  • FP&L to recover $196 million in 2012 * Progress Energy Florida request cut to $85.9 millionHOUSTON Oct 24 (Reuters) - Florida electric regulators on Monday approved requests from the state's two largest utilities to charge customers more than $280 million next year for work to develop four proposed nuclear reactors and to expand output at two existing plants.Florida is one of a handful of U.S. states in which laws were passed in the mid 2000s to revive the stagnant nuclear industry by offering utilities incentives to reduce the risk of building costly new reactors which take years to site, license and construct.The laws typically allow utilities to charge customers for certain project-related costs during the development and construction years in order to reduce long-term project financing costs.
  • The Florida Public Service Commission approved NextEra Energy's Florida Power & Light's full request to recover slightly more than $196 million from customers next year.Commissioners also agreed to allow Progress Energy's Florida utility to recover nearly $86 million next year for costs associated with a plan to build two new 2,200-MW reactors in Levy County, Florida.FP&L's amount includes costs related to the proposed 2,200-megawatt Turkey Point Units 6 and 7 and costs to add 450 MW of capacity at existing reactors at FP&L's Turkey Point and St. Lucie nuclear stations.That's up from only about $31 million approved for recovery in 2011 after a protracted dispute between the commission and the state's largest utility which has more than 4 million customers.
  • An FP&L spokesman said 90 percent of the funds requested for 2012 will pay for work to increase output at FP&L's existing reactors. About 29 MW is already in service with work to add the remaining 400 MW set for completion in 2013.Commercial operation of the new Turkey Point reactors, expected to cost between $12 billion and $18 billion, has been delayed about four years until 2022 and 2023 after FP&L said growth in power consumption slowed in the state during the economic recession.Progress Energy Florida initially sought $140.9 million, but the commission reduced that amount by more than $50 million under a 2009 plan deferring some early Levy costs due to the state's worsening economy.The proposed Levy County reactors, expected to cost about $20 billion, were originally set to begin operating in the 2016-17 time frame, but Progress delayed the timeline until at least 2020."We're pleased the commission confirmed our plan to make state-of-the-art nuclear power available to our customers in the state of Florida," Progress spokeswoman Suzanne Grant said.
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  • Progress Energy's 1.7 million Florida customers will pay about $2.93 per month for the first 1,000 kilowatt-hours of electricity for early Levy costs, down from more than $5 a month this year.FPL customers will pay about $2.20 per month for the first 1,000 kwh used.The Florida Legislature passed a law in 2006 to encourage development of new nuclear plants and the PSC adopted a rule to evaluate project-related costs each year. The nuclear-related charges were added to customer bills beginning in 2009.
D'coda Dcoda

Earthquake readiness of U.S. nuclear power plants is unclear [25Aug11] - 0 views

www.usatoday.com/...clear-safety-earthquakes_n.htm

shared by D'coda Dcoda on 29 Oct 11 - No Cached
  • Earthquakes are routinely measured by magnitude, or energy released. But the Nuclear Regulatory Commission (NRC)requires the nation's 104 nuclear reactors to withstand a predicted level of ground motion, or acceleration — something called g-force. What does that mean, magnitude-wise?
  • "I don't have what that translates into … unfortunately," NRC spokesman David McIntyre says. The agency released a statement Thursday to clarify its "earthquake measurements and design criteria," but it does not say what ground motion each reactor can handle. This muddiness heightens the concerns of industry critics, who have urged stricter safety rules after reactors at Japan's Fukushima Dai-ichi nuclear plant nearly melted down due to a magnitude-9.0 earthquake and tsunami on March 11.
  • A task force mandated by President Obama recommended in July that each U.S. plant be re-examined, given ongoing NRC research that shows the seismic risks for Eastern and Central U.S. nuclear power plants have increased. "The Virginia earthquake is now our local 911 call to stop delaying the implementation of stricter safety standards," Rep. Edward Markey, D-Mass., wrote in a letter this week to the NRC.
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  • He noted that while the North Anna nuclear facility, near the quake's epicenter in Mineral, Va., successfully shut down Tuesday, one of its backup generators failed to work. The plant declared an "alert" — the second lowest of NRC's four emergency classifications. It regained its electricity seven hours later but is not yet back in operation. Twelve other nuclear power plants along the East Coast and upper Midwest declared an "unusual event," the lowest classification. They resumed normal operations by the end of Tuesday. They are: Peach Bottom, Three Mile Island, Susquehanna and Limerick in Pennsylvania; Salem, Hope Creek and Oyster Creek in New Jersey; Calvert Cliffs in Maryland; Surry in Virginia; Shearon Harris in North Carolina and D.C. Cook and Palisades in Michigan.
  • "It's unclear how they (U.S. reactors) would stand up," says Edwin Lyman of the Union of Concerned Scientists, a non-profit group critical of nuclear energy. He says the lack of transparency about their preparedness "provides an additional smokescreen" that implies the public should just trust them. "It's not 'trust us.' It's a regulatory process," says Steve Kerekes, spokesman of the Nuclear Energy Institute, an industry group. He says each plant looks at historic seismic activity in its area, designs against that and upgrades systems as needed. Last year alone, he says, the industry spent about $7 billion on capital improvements.
  • Yet not all that money was spent on safety, and the regulatory process is "based on industry self-assessment," says Robert Alvarez, scholar at the Institute for Policy Studies and former senior adviser at the Department of Energy. "You can imagine the conflicts of interest that arise." So how prepared each nuclear plant is for an earthquake, he says, is "pretty much what the operators say it is."
  • Jim Norvelle, spokesman of Dominion Virginia Power, which operates the North Anna plant, says its two reactors were built to withstand ground motion of 0.12g to 0.18g, depending on soil composition. He says that translates into magnitudes of 5.9 to 6.2. He says that although one backup diesel generator leaked when Tuesday's quake cut off power, the plant had a spare generator and redundant safety systems to keep the reactors' radioactive cores cool.
D'coda Dcoda

Pictures-Ten Oldest U.S. Nuclear Plants: Post-Japan Risks [19Jul11] - 0 views

news.nationalgeographic.com/...ldest-nuclear-plants-in-the-us

shared by D'coda Dcoda on 29 Oct 11 - No Cached
  • The world's largest nuclear energy producer, the United States, Tuesday aired its first detailed public examination of whether stronger safety standards are needed in light of Japan's Fukushima Daiichi nuclear disaster.Although the U.S. Nuclear Regulatory Commission (NRC) task force concluded that the sequence of events that caused Japan's crisis was unlikely to recur in the United States, the panel has urged a new focus on preparing for the unexpected.(Related: "How is Japan's Nuclear Disaster Different?)Especially at issue is how to deal with "beyond design-basis" risks, events considered too unlikely to be factored in when the plants were being designed. The U.S. task force recommended that a framework of "extended design-basis" requirements be established for the 104 reactors in the United States. This is especially important, task force member Gary Holahan said, in light of the fact that "many of the older plants might have less robust seismic, flooding, and other features."
  • Part of the concept of the framework is for the NRC to articulate” expected safety requirements, and to test all plants, no matter their age or design, against that same standard, said Holahan, deputy director of NRC's office of new reactors.The post-Fukushima inspection reports that NRC ordered for all U.S. nuclear power plants provide a window into risks that the task force says the agency should address.
  • For instance, in their April visit to the oldest U.S. nuclear power plant, Exelon's Oyster Creek, near Toms River, New Jersey, close to the shore, the inspectors noted that if power were lost, emergency venting procedures "could result in hydrogen accumulation in the reactor building." Such a build-up is believed to have caused the explosions at Fukushima Daiichi, which, like Oyster Creek, had boiling water reactors with Mark 1 containment systems. Among the NRC task force's recommendations is that reliable hardened vent designs be required in such reactors. (Fukushima and most of the 31 U.S. boiling water reactors have hardened vent designs; the task force is urging steps to make them more reliable.)Here's a look at some of the other post-Fukushima concerns raised by inspectors at the ten oldest U.S. nuclear power plants.
Dan R.D.

Is nuclear power fair for future generations? Realities of nuclear power production [05... - 0 views

www.sciencedaily.com/...110505083731.htm

public opinion psychology ethics nuclear

shared by Dan R.D. on 28 Oct 11 - No Cached
  • ScienceDaily (May 5, 2011) — The recent nuclear accident in Fukushima Daiichi in Japan has brought the nuclear debate to the forefront of controversy. While Japan is trying to avert further disaster, many nations are reconsidering the future of nuclear power in their regions. A study by Behnam Taebi from the Delft University of Technology, published online in the Springer journal Philosophy & Technology, reflects on the various possible nuclear power production methods from an ethical perspective: If we intend to continue with nuclear power production, which technology is most morally desirable?
  • Dr. Taebi said, "Discussions on nuclear power usually end up in a yes/no dichotomy. Meanwhile the production of nuclear power is rapidly growing. Before we can reflect on the desirability of nuclear power, we should first distinguish between its production methods and their divergent ethical issues. We must then clearly state, if we want to continue on the nuclear path, which technology we deem desirable from a moral perspective. Then we can compare nuclear with other energy systems. The state of the art in nuclear technology provides us with many more complicated moral dilemmas than people sometimes think."
D'coda Dcoda

Decision to build Bellefonte 1 [04Nov11] - 0 views

www.world-nuclear-news.org/uild_Bellefonte_1_1908111.html

shared by D'coda Dcoda on 04 Nov 11 - No Cached
  • Tennessee Valley Authority has decided to complete a nuclear reactor at Bellefonte - selling and leasing back another new reactor to pay for it.
  • Tennessee Valley Authority has decided to complete a nuclear reactor at Bellefonte - selling and leasing back another new
  • To pay for all this, TVA will raise cash by selling two new power plants it is now in the process of building before leasing them back from the new owners. One comprises two gas turbines at the John Sevier fossil power plant, the other is Watts Bar 2, another large nuclear reactor TVA is completing. The plants will be sold separately, most likely to financial institutions interested in holding industrial assets. TVA will continue to control, maintain and operate them.   Chief financial officer John Thomas said TVA had to use alternative methods to finance its investment because of statutory limits on the amount of bonds it could issue. The leaseback option would be "slightly more expensive" than bonds, he said, but would be cheaper overall than increasing public and commercial rates by more than the 2% approved yesterday. The final analysis will not come until buyers have been found for the new power plants at the end of a competitive process.
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  • The decision yesterday by TVA's board brings to an end some five years of deliberation by the non-profit firm that manages power, water and other resources in the US state. Bellefonte 1 is a Babcock & Wilcox pressurized water reactor currently considered 55% complete. A $4.9 billion project should see it begin operation by 2020 to generate 1260 MWe.   At the same time, TVA will purchase a 900 MWe combined-cycle gas power plant from a subsidiary of Kelson Energy. It is also going to fit sulphur dioxide and particulate control systems to its older Gallatin and Allen coal power plants to bring them up to "clean standards."
  • TVA's president and CEO, Tom Kilgore, said completing Bellefonte 1 was cheaper on a per-MW basis than the cost of replacing any of its fossil plants. The $4.9 billion project works out at a cost of $3888 per kilowatt of installed capacity. As essentially a brand-new reactor, the sale of Watts Bar 2 will be unprecedented and the price is impossible to predict. In the last decade prices seen in the US for old reactors, normally after some 30 years of service, have trended upwards from less than $400 to over $874 per kilowatt. Exceptionally, EDF paid some $2253 per kilowatt overall for its shares in Calvert Cliffs, Nine Mile Point and RE Ginna plants in 2009 when investing in Constellation Energy.
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