Mysteries of the Oort cloud at the edge of our solar system

The entirely theoretical cloud of icy space debris marks the frontiers of our solar system.

By Joshua Rapp Learn  |  Published: Thursday, August 5, 2021

RELATED TOPICS: THE SOLAR SYSTEM

Naeblys/Shutterstock

The Oort cloud represents the very edges of our solar system. The thinly dispersed collection of icy material starts roughly 200 times farther away from the sun than Pluto and stretches halfway to our sun’s nearest starry neighbor, Alpha Centauri. We know so little about it that its very existence is theoretical — the material that makes up this cloud has never been glimpsed by even our most powerful telescopes, except when some of it breaks free.

“For the foreseeable future, the bodies in the Oort cloud are too far away to be directly imaged,” says a spokesperson from NASA. “They are small, faint, and moving slowly.”

Aside from theoretical models, most of what we know about this mysterious area is told from the visitors that sometimes swing our way every 200 years or more — long period comets. “[The comets] have very important information about the origin of the solar system,” says Jorge Correa Otto, a planetary scientist the Argentina National Scientific and Technical Research Council (CONICET).\

A Faint Cloud, in Theory

The Oort cloud’s inner edge is believed to begin roughly 1,000 to 2,000 astronomical units from our sun. Since an astronomical unit is measured as the distance between the Earth and the sun, this means it’s at least a thousand times farther from the sun than we are. The outer edge is thought to go as far as 100,000 astronomical units away, which is halfway to Alpha Centauri. “Most of our knowledge about the structure of the Oort cloud comes from theoretical modeling of the formation and evolution of the solar system,” the NASA spokesperson says.

While there are many theories about its formation and existence, many believe that the Oort cloud was created when many of the planets in our solar system were formed roughly 4.6 billion years ago. Similar to the way the Asteroid Belt between Mars and Jupiter sprung to life, the Oort cloud likely represents material left over from the formation of giant planets like Jupiter, Neptune, Uranus and Saturn. The movements of these planets as they came to occupy their current positions pushed that material past Neptune’s orbit, Correa Otto says.

Another recent study holds that some of the material in the Oort cloud may be gathered as our sun “steals comets” orbiting other stars. Basically, the theory is that comets with extremely long distances around our neighboring stars get diverted when coming into closer range to our sun, at which point they stick around in the Oort cloud.

The composition of the icy objects that form the Oort cloud is thought to be similar to that of the Kuiper Belt, a flat, disk-shaped area beyond the orbit of Neptune we know more about. The Kuiper Belt also consists of icy objects leftover from planet formation in the early history of our solar system. Pluto is probably the most famous object in this area, though NASA’s New Horizons space probe flew by another double-lobed object in 2019 called Arrokoth — currently the most distant object in our solar system explored up close, according to NASA.

“Bodies in the Oort cloud, Kuiper belt, and the inner solar system are all believed to have formed together, and gravitational dynamics in the solar system kicked some of them out,” the NASA spokesperson says.

Visitors from the Edge of our Solar System

Estonian philosopher Ernst Öpik first theorized that long-period comets might come from an area at the edge of our solar system. Then, Dutch astronomer Jan Oort predicted the existence of his cloud in the 1950s to better understand the paradox of long-period comets.

Oort's theory was that comets would eventually strike the sun or a planet, or get ejected from the solar system when coming into closer contact with the strong orbit of one of those large bodies. Furthermore, the tails that we see on comets are made of gasses burned off from the sun’s radiation. If they made too many passes close to the sun, this material would have burned off. So they must not have spent all their existence in their current orbits. “Occasionally, Oort cloud bodies will get kicked out of their orbits, probably due to gravitational interactions with other Oort cloud bodies, and come visit the inner solar system as comets,” the NASA spokesperson says.

Correa Otto says that the direction of comets also supports the Oort cloud’s spherical shape. If it was shaped more like a disk, similar to the Kuiper Belt, comets would follow a more predictable direction. But the comets that pass by us come from random directions. As such, it seems the Oort cloud is more of a shell or bubble around our solar system than a disk like the Kuiper Belt. These long-period comets include C/2013 A1 Siding Spring, which passed close to Mars in 2014 and won’t be seen again for another 740,000 years.

“No object has been observed in the distant Oort cloud itself, leaving it a theoretical concept for the time being. But it remains the most widely-accepted explanation for the origin of long-period comets,” NASA says.

The Oort cloud, if it indeed exists, likely isn’t unique to our own solar system. Correa Otto says that some astronomers believe these clouds exist around many solar systems. The trouble is, we can’t even yet see our own, let alone those of our neighboring systems. The Voyager 1 spacecraft is headed in that direction — it’s projected to reach the inner edge of our Oort cloud in roughly 300 years. Unfortunately, Voyager will have long since stopped working.

“Even if it did [still work], the Sun’s light is so faint, and the distances so vast, that it would be unlikely to fly close enough to something to image it,” the NASA spokesperson says. In other words, it would be difficult to tell you’re in the Oort cloud even if you were right inside it.

Investigation Into the Origin of Elements in the Universe Yields New Insights

TOPICS:AstrophysicsAtomic PhysicsDOE

By U.S. DEPARTMENT OF ENERGY AUGUST 5, 2021

A key reaction in the slow neutron-capture process that forms elements occurs less frequently than previously thought.

The Science

The slow neutron-capture process (the s-process) is one of the nucleosynthesis processes that occurs in stars. It results in about half of the elements heavier than iron in the universe. Two important reactions involved in the s-process are Neon-22 (alpha, gamma) and Neon-22 (alpha, neutron). In these reactions, neutron-rich Neon-22 captures alpha-particles. The capture produces Magnesium-26 in an excited state, meaning it has received extra energy. It then releases energy by emitting either a gamma ray, leading to Magnesium-26 in a normal state, or a neutron, leading to Magnesium-25. The rates of both the Neon-22 (alpha, gamma) and Neon-22 (alpha, neutron) reactions have significant effects on the s-process. This affects the abundances of elements such as Selenium, Krypton, Rubidium, Strontium, and Zirconium.

An isotope of Neon (22Ne) captures an alpha-particle (α) to create Magnesium-26 (26Mg) in an excited state. The excited Magnesium-26 then releases energy by emitting a gamma ray (γ), leading to Magnesium-26 or a neutron, leading to Magnesium-25. Credit: Image courtesy of Dustin Scriven, Texas A&M University

The Impact

Scientists are trying to answer the question, what is the origin of elements in the universe? The answer is extremely complex. It requires a collaborative effort by researchers in many fields and an enormous amount of experimental data. One part of answering this question is understanding the specific processes that create elements heavier than iron. Some of these elements form through particular nuclear reactions inside stars that involve neutron captures (the s-process). Neutrons are unstable and need to be produced continuously to fuel this process. Determining the intensities of neutron source reactions is important to understanding this nucleosynthesis scenario.

Summary

Two reactions have a strong influence on the neutron flux during the s-process, 22Ne(α, γ)26Mg and 22Ne(α, n)25Mg. The probabilities of these reactions occurring are difficult to measure directly because these probabilities (called reaction cross sections) are extremely low at the energies relevant for stellar nucleosynthesis. A team of nuclear physicists used two indirect methods to determine the probabilities for both reactions. Both methods used a 22-Neon beam produced at the Texas A&M University Cyclotron Institute. In one study, the team measured the likelihood for the most relevant excited states in 26-Magnesium to decay by alpha-particles. The other experiment involved direct measurements of neutron/gamma branching ratios for the same excited states. Combining these studies led researchers to a consistent conclusion: that the actual probability of the 22Ne(α, n)25Mg reaction occurring is lower than the widely accepted probability by a factor of three. This finding significantly changes the final s-process abundances of some elements, such as Selenium, Krypton, Rubidium, Strontium, and Zirconium.

References

Jayatissa, H., et al. Constraining the ²²Ne(α,γ)²⁶Mg and ²²Ne(α,n)²⁵Mg reaction rates using sub-Coulomb α-transfer reactions. Physics Letters B 802, 135267 (2020). [DOI: 10.1016/j.physletb.2020.135267]

Ota, S. et al. Decay properties of ²²Ne + α resonances and their impact on s-process nucleosynthesis. Physics Letters B 802, 135256 (2020). [DOI: 10.1016/j.physletb.2020.135256]

Funding

This research was supported by the Department of Energy (DOE) Office of Science, Office of Nuclear Physics; by the National Nuclear Security Administration through the Center for Excellence in Nuclear Training and University Based Research (CENTAUR); and the Nuclear Solutions Institute at Texas A&M University. Two of the authors were also supported by The Welch Foundation. Three of the authors were also supported by the U.K. Science and Technology Facilities Council.

Huge ring around a black hole

Credit: X-ray: NASA /

 CXC / U.Wisc-Madison / S.Heinz et al.; Optics / IR: PanSTARRS

This image features a magnificent set of rings around a black hole, captured using NASA’s Chandra X-ray Observatory and Neil Gerelswift Observatory. X-ray images of giant rings reveal information about dust in our galaxy, using principles similar to those used in clinics and airports.

Black holes are part of a star system called V404 Cygni at about 7,800. Light year Away from the earth. Black holes are actively attracting matter from a companion star, which weighs about half the mass of the Sun, to a disk around an invisible object. Astronomers call these systems “X-ray binaries” because this material glows with X-rays.

On June 5, 2015, Swift discovered an X-ray burst from the V404 Cygni. Burst created a high-energy ring from a phenomenon known as the light echo.Instead of the sound waves bouncing off the canyon wall, a light echo was generated around the V404 Cygni when a burst of X-rays from the black hole system bounced off. Dust Clouds between V404 Cygni and the Earth. Cosmic dust is not like household dust, it’s like smoke, it’s made up of small solid particles.

In this composite image, X-rays from Chandra (light blue) are combined with optical data from the PanSTARRS telescope in Hawaii, which shows the stars in the field of view. This image contains eight separate concentric rings. Each ring is created by X-rays from the V404 Cygni flare observed in 2015 and reflects off various dust clouds. (The artist’s illustration illustrates how the rings Chandra and Swift saw were created. To simplify the graphic, the illustration shows only four rings instead of eight.

A team of researchers led by Sebastian Heinz of the University of Wisconsin in Madison has conducted 50 Swift observations of the system between June 30 and August 25, 2015 and July 11-25, 2015. We analyzed the Chandra observations made in. Chandra’s operator intentionally placed the V404 Cygni between the detectors so that another bright burst would not damage the equipment.

The ring tells astronomers not only about the behavior of black holes, but also about the landscape between the V404 signi and the Earth. For example, the diameter of an X-ray ring reveals the distance to an intervening cloud of dust that bounces off light. When the clouds are close to the earth, the ring looks big and vice versa. Since the X-ray burst lasted for a relatively short time, the optical echo appears as a narrow ring rather than a wide ring or halo.

Researchers also used rings to examine the properties of the dust cloud itself. They compared the X-ray spectrum (that is, the brightness of X-rays over a range of wavelengths) with computer models of dust of various compositions. Different dust compositions absorb different amounts of low-energy X-rays and are undetectable by Chandra. This is a principle similar to how different parts of our body and luggage absorb different amounts of x-rays and provide information about their structure and composition.

The team determined that the dust was likely to contain a mixture of graphite and silicate particles. In addition, Chandra’s analysis of the inner ring revealed that the density of dust clouds was not uniform in all directions. Previous studies have assumed that this is not the case.

This artist’s illustration details how the ring structure seen by Chandra and Swift is made. Each ring is caused by x-rays bouncing off various dust clouds. If the clouds are close to us, the ring will look big. The result is a set of concentric rings of different apparent sizes, depending on the distance of the intervening clouds from us. Credits: University of Wisconsin-Madison / S.Heinz school

A paper explaining the results of V404 Cygni was published in The Astrophysical Journal (preprint) published on July 1, 2016. The authors of this study are Sebastian Heinz, Lia Corrales (University of Michigan). Randall Smith (Center for Astrophysics | Harvard & Smithsonian); Niel Brandt (Penn State University); Peter Jonker (Netherlands Institute for Space Research); Richard Protokin (University of Nevada, Reno); and Joey Nielson (Villanova University).

This result is related to a similar discovery of the X-ray binary Circinus X-1, which contains neutron stars rather than black holes, in the June 20, 2015 issue of The Astrophysical Journal, “The Lord of the Rings: Kinematic Distance from Giant X-ray Light Echo to Circinus X-1” (preprint). The study was also led by Sebastian Heinz.

Several papers are published annually reporting the study of the 2015 V404 Cygni explosion that caused these rings. Earlier explosions were recorded in 1938, 1956, and 1989, so astronomers could still take years to continue analyzing the 2015 explosion.

---

Swift satellite reveals black hole bullseye

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For more information:
S. Heinz et al., V404 Cygni’s 2015 X-ray Dust Scattering Echo Chandra and Swift Joint View, Astrophysical Journal (2016). DOI: 10.3847 / 0004-637X / 825/1/15 , arxiv.org/abs/1605.01648

Provided by
Chandra X-ray Center

Quote: V404 Cygni: https: //phys.org/news/2021-08-v404-cygni-huge-black-hole.html Black hole acquired on August 5, 2021 (August 5, 2021) Huge ring around

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Huge ring around a black hole

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Is the Universe a Roguelike? - What Up Science

Aug 6, 2021

IGN
Nobel Laureate Sir Roger Penrose just went to the mat for a cyclical model of the Universe. That means this has all happened before and it will all happen again, including you reading this description of this video. Neat! But is it true? We'll dig into that, trace the history of the cyclical concept of time, and make some spurious claims about whether we may or may not be living in a giant roguelike. It touches on games like Deathloop and 12 Minutes, shows like Rick and Morty and Futurama, and it's all wrapped up in a neat little science news package by your humble host Mr. Michael Swaim. #IGN #WhatUpScience

DOUBLING DOWN ON TROUBLE

Zero-carbon bitcoin? The owner of a Pennsylvania nuclear plant thinks it could strike gold

Talen Energy plans to build a $400 million bitcoin mine at its Pa. nuclear plant.

"I think this is a great opportunity to prolong the life of a lot of plants."

The Susquehanna Steam Electric Station near Berwick, Pa., is a two-unit nuclear reactor owned by Talen Energy. Talen announced the week of Aug. 1, 2021, that it plans to go into partnership with a cryptocurrency producer, TeraWulf Inc., to build a $400 million bitcoin mining operation at the Luzerne County plant that will be called Nautilus Cryptomine.
Talen Energy

by Andrew Maykuth
Published
Aug 6, 2021

Could bitcoin mining be the salvation of the embattled nuclear energy industry in America?

The owners of several nuclear power plants, including two in Pennsylvania, have formed ventures with cryptocurrency companies to provide the electricity needed to run computer centers that “mine” bitcoin. Since nuclear energy does not emit greenhouse gases, the project’s investors say, the zero-carbon bitcoin would address climate concerns that have tarnished the energy-intensive cryptocurrency industry.

Talen Energy, the owner of the Susquehanna Steam Electric Station near Berwick, Pa., announced this week that it has signed a deal with TeraWulf Inc., an Easton, Md. cryptocurrency mining firm, to build a giant bitcoin factory next to its twin reactors in northern Pennsylvania. The first phase of the venture, dubbed Nautilus Cryptomine, could cost up to $400 million.

Talen’s project could eventually use up to 300 megawatts — or 12% of Susquehanna’s 2,500 MW capacity. It’s the second bitcoin-mining venture in the last month that involves owners of Pennsylvania nuclear facilities.

Last month Energy Harbor Corp., the former power-generation subsidiary of First Energy Corp., announced it signed a five-year agreement to provide zero-carbon electricity to a new bitcoin mining center operated by Standard Power in Coshocton, Ohio. Energy Harbor owns two nuclear units in Ohio and the twin-unit Beaver Valley Power Station in Western Pennsylvania.

A nuclear fission start-up, Oklo, also announced last month it signed a 20-year deal with a bitcoin miner to supply it with power, though the company has not yet built a power plant.

In recent years, commercial nuclear operators have struggled to compete in competitive electricity markets against natural gas plants and upstart renewable sources such as wind and solar. Unfavorable market conditions have hastened the retirements of several single-unit reactors, such as Three Mile Island Unit 1 in Pennsylvania. Lawmakers in New Jersey, New York and Illinois have enacted nuclear bailouts, paid by electricity customers, to stave off early retirement for other plants.

The cryptocurrency deals would provide nuclear generators with reliable outlets for their power, and bitcoin miners with predictable sources of power at cheap prices, along with a zero-carbon cachet.

Photo illustration showing the Susquehanna Steam Electric Station near Berwick, Pa., a two-unit nuclear reactor owned by Talen Energy (formerly owned by PPL Corp.), and a proposed 200,000 square-foot Talen Energy

“Nuclear energy is uniquely positioned to provide power to crypto mining companies and other major energy users who have committed to a carbon-free future,” John Kotek, senior vice president of policy development and government affairs at Nuclear Energy Institute, said in an email.

The nuclear industry views the crypto craze not as a crutch but as a launching pad for expansion. “U.S. nuclear power plants are ready and able to supply miners with abundant, reliable carbon-free power while also providing new business pathways for the nuclear developers and utilities, increasing their operating profits, and potentially accelerating the deployment of the next generation of reactors,” Kotek said.


Nuclear producers aren’t the only power generators getting in on the trend. Stronghold Digital Mining, a bitcoin miner that registered last month for a $100 million initial stock offering, plans to build its bitcoin mining operation in northwestern Pennsylvania, powered from Venango County waste coal. While its bitcoin would not be zero-carbon, it would reduce environmentally harmful piles of waste coal.

Energy and cryptocurrency experts say several trends are shifting the market in favor of U.S. nuclear power producers.

In May, Chinese regulators announced new measures to limit bitcoin mining in several regions that failed to meet Beijing’s energy-use targets. Bitcoin production levels have fallen since then, forcing bitcoin producers to relocate to places with low operating costs and cool climates to reduce the costs of cooling the bitcoin data centers. The state of Washington, which has lots of inexpensive hydroelectric power, has undergone a huge boom in bitcoin mining.

How mining is done

Bitcoin is a peer-to-peer virtual currency, operating without a central authority, and which can be exchanged for traditional currency such as the U.S. dollar. It is the most successful of hundreds of attempts to create virtual money through the use of cryptography, the science of making and breaking codes — hence, they are called cryptocurrency.

Bitcoin mining is built around blockchain technology, and it involves generating a string of code that decrypts a collection of previously executed bitcoin transactions. Successful decryption is rewarded with a new bitcoin. The supply of bitcoins is limited to 21 million — nearly 90% have already been mined. So the remaining bitcoins become increasingly scarce and more difficult to extract.

Data centers operated by bitcoin miners randomly generate code strings, called “hashes,” to solve the puzzle and earn new coins. Worldwide, miners on the bitcoin network generate more than 100 quintillion hashes per second — that’s 100,000,000,000,000,000,000 guesses per second, according to Blockchain.com. The first phase of the Nautilus project in Pennsylvania would generate five quintillion hashes per second.

Such guesswork requires muscular computing power, robust internet connections, and lots of electricity. Smaller bitcoin miners have teamed up in consortiums to pool their computing power. Bigger players have built huge data centers devoted exclusively to producing lines of random code.

An electrician checks cryptocurrency computer mining rigs in Hennepin, Ill., where Sangha Systems is converting the bitcoin mining facility to solar power to address growing concerns about the industry's carbon footprint. The owner of a Pennsylvania nuclear power plant announced that it would form a partnership with a cryptocurrency mining operation to produce and market "zero carbon" bitcoin produced from nuclear energy.
Antonio Perez / MCT

“Mining cryptocurrency is an international, profitable, and energy-intensive business,” ScottMadden a management consulting firm, said in a paper it published last year. Bitcoin mining consumes an estimated 0.5% of the electricity produced worldwide or about as much as the country of Greece.

Some lawmakers have called for greater regulation of cryptocurrency, citing the enormous amount of resources required to produce it. “There are computers all over the world right now spitting out random numbers around the clock, in a competition to try to solve a useless puzzle and win the bitcoin reward,” Sen. Elizabeth Warren (D., Mass.) said in June, calling for a crackdown on “environmentally wasteful cryptocurrencies.”

Why possible numbers look good

But as a business proposition, bitcoin has appeal. ScottMadden, the consulting firm, suggested last year that nuclear operators in some states were in a unique position to profit from cryptocurrency ventures.

Diverting 1 megawatt of power to an efficient mining operation could conservatively generate top-line revenue of $900,000 a year and profits of $650,000, not accounting for cooling, repairs, or technicians, according to ScottMadden. Its analysis predicts that a project could break even in about 15 months.

The consulting firm’s conceptual project was based upon a bitcoin price of $9,275. The price of a bitcoin last week varied between $38,000 and $42,000.

Such numbers no doubt got the attention of Talen Energy, which plans to divert about 180 MW to the first phase of the Nautilus Cryptomine, which would be producing bitcoin at the Susquehanna plant in Luzerne County.

”I think it’s a great opportunity for our plant,” said Dustin Wertheimer, vice president and divisional chief financial officer of Talen Energy. He is based in Allentown, home to Talen’s previous owner, PPL Corp. Talen is now based in the Woodlands, Texas.

Unlike other crypto projects in which the power generator is an arms-length electricity supplier, the Nautilus Cryptomine is a 50-50 venture between Talen and TeraWulf. The project would be directly connected to the Susquehanna plant — “behind the meter,” in industry parlance — and would avoid any transmission costs from the grid.

Bitcoin tokens. The price of a bitcoin traded for about $40,000 last week.

Dan Kitwood / MCT

The direct connection also guarantees that the operation is sourced exclusively with carbon-free energy, Wertheimer said.

“You’ve seen some of the press and the negative publicity that bitcoin has received recently and the impact of fossil fuel,” Wertheimer said. “So that’s a great thing for us to have a direct connection into a carbon-free power source.”

The cryptomine would be located inside a 200,000-square-foot building — about four football fields. The mining operation would be built on a data center campus that Talen is developing next to the Susquehanna plant. The data center would generate about 1,000 construction jobs, Wertheimer said. The cryptomine would employ about 50 people to operate.

The first phase of the project would cost about $350 million to $400 million. The Nautilus venture is negotiating with fiber-optic providers to bring in super-charged internet connections required to transmit and receive the huge amounts of code it generates, Wertheimer said.

“As you look across the United States, and you look at kind of the challenges that are facing nuclear plants, I think this is a great opportunity to prolong the life of a lot of plants,” he said.

The Inquirer explores what work will look like in the pandemic and beyond.
The Future of Work is produced with support from the William Penn Foundation and the Lenfest Institute for Journalism. Editorial content is created independently of the project’s donors.

Published
Aug. 6, 2021

Andrew Maykuth
I cover how we produce and use energy, as well as its impact on the economy and the environment.

China Says It's Closing in on Thorium Nuclear Reactor

With prototype reportedly firing up in September, country teases commercial thorium power by 2030

PRACHI PATEL
04 AUG 2021



Thorium on the periodic table of elements.
KLAUDIA KILMAN/ALAMY


There is no denying the need for nuclear power in a world that hungers for clean, carbon-free energy. At the same time, there's a need for safer technologies that bear less proliferation risk. Molten salt nuclear reactors (MSRs) fit the bill—and, according to at least one source, China may be well on their way to developing MSR technology.

Government researchers there unveiled a design for a commercial molten salt reactor (MSR) that uses thorium as fuel, the South China Morning Post reported recently. A prototype reactor, the paper said, should be ready this month for tests starting in September. Construction of the first commercial reactor being built in the Gansu province should be complete, they noted, by 2030.

If all goes well with the prototype, says a report in Live Science, the Chinese government plans to build several large MSRs. According to the World Nuclear Association, the country is eyeing thorium MSRs as a source of energy especially for the northwestern portion of the country, which has lower population density and an arid climate.

MSRs are attractive for arid regions because instead of the water used by conventional uranium reactors, MSRs use molten fluoride salts to cool their cores. Uranium or thorium fuel can be mixed into the coolant salt. Thorium MSRs have the advantage of being more abundant and cheaper.

China's experimental reactor won't be the world's first. Researchers at Oak Ridge National Laboratory (ORNL) pioneered thorium-based MSRs in the 1950s for nuclear aircraft propulsion as part of the Manhattan Project. A 7.4 MWth experimental reactor operated at the laboratory over a period of four years—although only a portion of its fuel was derived from uranium-233 bred from thorium in other reactors. This MSR technology was eventually shelved because the Pentagon favored the uranium fast breeder reactor, says Charles Forsberg, Principal Research Scientist at MIT's department of Nuclear Science and Engineering and former nuclear researcher at ORNL.

Scientists in China are now building on the same basic MSR technology developed at ORNL. The Chinese government had a small, short-lived knowledge exchange program with ORNL. But most of the thorium reactor-related intellectual property from ORNL is in the public domain, and China appears to have made some use of it. "The real data mine is the thousands of published reports in 1960s and '70s that are found in the open literature," Forsberg says.

Plus, recent technology developments have made it more feasible to build MSRs, he adds. This includes modern instrumentation that can unveil exactly what goes on in the reactor—but also includes equipment that finds parallel use, such as high-temperature salt pumps used in today's concentrated solar power plants that store heat via molten salts.

The real data mine is the thousands of published reports in 1960s and '70s that are found in the open literature.

"So now if you want to build a salt pump for a MSR you go talk to your local friendly CSP pump suppliers for a slightly different salt composition," Forsberg says. "That makes a tremendous difference in your development program. You have fifty years' worth of new technology to tap into."

But even though France, India, Japan, Norway, and the U.S. are all reportedly working on thorium nuclear reactors, none of these countries have outlined plans for commercial reactors yet. A handful of private sector developers are working hard to deploy MSRs within the next decade. The closest is probably Alameda, Calif.-based Kairos Power, which plans to have a 50 MW demonstration reactor operational in Oak Ridge, Tenn. by 2026.

Yet China leads global MSR research, according to the World Nuclear Association, and it's no surprise that the country is forging ahead faster, Forsberg says. The country's talent pool in nuclear engineering, he says, is quite substantial. "You put a lot of talented people on a project, and it works," he says. "They'll be successful even if it takes them a while."


Prachi Patel
is a freelance journalist based in Pittsburgh. She writes about energy, biotechnology, materials science, nanotechnology, and computing.

 

China Starts Constructing $17-Billion Nuclear Power Plant

By Tsvetana Paraskova - Aug 06, 2021, 4

China started this week construction work on a new US$17-billion nuclear power plant project, for which it will install Russian nuclear reactors at the Xudabao project in northeastern China, World Nuclear News reports.

The Xudabao 3 unit is the first of four units at the plant to see the beginning of construction. Russia’s Rosatom will design the nuclear island and will provide equipment. The Russian firm will also provide commissioning services for the equipment it will have supplied. The Russians will also provide the construction and equipment for the Xudabao 4 unit, whose construction is expected to begin in 2022.

The two units are currently expected to be commissioned in 2027 or 2028.

Construction for the Xudabao units 1 and 2 has yet to begin, according to World Nuclear News.

Last month, China had to close down a nuclear power plant in the province of Guangdong in the south because it was damaged. The operator, however, insisted that the Taishan nuclear plant does not have any major safety issue.  

A month before that, French company Framatome, a subsidiary of French energy giant EDF, issued a statement related to Taishan’s reactor number 1, saying that it “is supporting resolution of a performance issue with the Taishan Nuclear Power Plant.”

The Taishan nuclear plant could turn into an “imminent radiological threat,” the part owner of the facility, the French company has told the United States, CNN reported in the middle of June, citing U.S. officials and a letter of the French firm it had obtained.

A week before the Chinese operator of the plant announced it would shut down for maintenance, France’s EDF, which holds 30 percent in the TNPJVC joint venture operating Taishan, had said in a statement that it would have shut the plant if it were in France.

“EDF's operating procedures for the French nuclear fleet would lead EDF, in France, to shut down the reactor in order to accurately assess the situation in progress and stop its development. In Taishan, the corresponding decisions belong to TNPJVC,” the French company said.

By Tsvetana Paraskova for Oilprice.com

 

Long-Theorized Neutron-Clustering Effect in Nuclear Reactors Demonstrated for First Time

TOPICS:DOEEnergyLos Alamos National LaboratoryNeutronsNuclear Energy

By LOS ALAMOS NATIONAL LABORATORY AUGUST 5, 2021

Reactor Operator Nicholas Thompson of Los Alamos National Laboratory helps to set up the neutron clustering measurements at the Walthousen Reactor Critical Facility at Rensselaer Polytechnic Institute in Schenectady, NY. Credit: Los Alamos National Laboratory

Long-theorized phenomenon observed in a working reactor could improve reactor safety, according to a new study.

For the first time, the long-theorized neutron-clustering effect in nuclear reactors has been demonstrated, which could improve reactor safety and create more accurate simulations, according to a new study recently published in the journal Nature Communications Physics.

“The neutron-clustering phenomenon had been theorized for years, but it had never been analyzed in a working reactor,” said Nicholas Thompson, an engineer with the Los Alamos Advanced Nuclear Technology Group. “The findings indicate that, as neutrons fission and create more neutrons, some go on to form large lineages of clusters while others quickly die off, resulting in so-called ‘power tilts,’ or asymmetrical energy production.”

Understanding these clustering fluctuations is especially important for safety and simulation accuracy, particularly as nuclear reactors first begin to power up. The study was a collaboration with the Institute for Radiological Protection and Nuclear Safety (IRSN) and the Atomic Energy Commission (CEA), both located in France.

“We were able to model the life of each neutron in the nuclear reactor, basically building a family tree for each,” said Thompson. “What we saw is that even if the reactor is perfectly critical, so the number of fissions from one generation to the next is even, there can be bursts of clusters that form and others that quickly die off.”

This clustering phenomenon became important to understand because of a statistical concept known as the gambler’s ruin, believed to have been derived by Blaise Pascal. In a betting analogy, the concept says that even if the chances of a gambler winning or losing each individual bet are 50 percent, over the course of enough bets the statistical certainty that the gambler will go bankrupt is 100 percent.

In nuclear reactors, from generation to generation, each neutron can be said to have a similar 50 percent chance of dying or fissioning to create more neutrons. According to the gambler’s ruin concept, the neutrons in a reactor might then have a statistical chance of dying off completely at some future generation, even though the system is at critical.

This concept had been studied widely in other scientific fields, such as biology and epidemiology, where this generational clustering phenomenon is also present. By drawing on this related statistical math, the research team was able to analyze whether the gambler’s ruin concept would hold true for neutrons in nuclear reactors.

“You would expect this theory to hold true,” says Jesson Hutchinson, who works with the Laboratory’s Advanced Nuclear Technology Group. “You should have a critical system that, while the neutron population is varying between generations, runs some chance of becoming subcritical and losing all neutrons. But that’s not what happens.”

To understand why the gambler’s ruin concept didn’t hold true, researchers used a low-power nuclear reactor located at the Walthousen Reactor Critical Facility in New York. A low-power reactor was essential for tracking the lifespans of individual neutrons because large-scale reactors can have trillions of interactions at any moment. The team used three different neutron detectors, including the Los Alamos-developed Neutron Multiplicity 3He Array Detector (NoMAD), to trace every interaction inside the reactor.

The team found that while generations of neutrons would cluster in large family trees and others died out, a complete die-off was avoided in the small reactor because of spontaneous fission, or the non-induced nuclear splitting of radioactive material inside reactors, which creates more neutrons. That balance of fission and spontaneous fission prevented the neutron population from dying out completely, and it also tended to smooth out the energy bursts created by clustering neutrons.

“Commercial-sized nuclear reactors don’t depend on the neutron population alone to reach criticality, because they have other interventions like temperature and control rod settings,” Hutchinson said. “But this test was interested in answering fundamental questions about neutron behavior in reactors, and the results will have an impact on the math we use to simulate reactors and could even affect future design and safety procedures.”

Reference: “Patchy nuclear chain reactions” by Eric Dumonteil, Rian Bahran, Theresa Cutler, Benjamin Dechenaux, Travis Grove, Jesson Hutchinson, George McKenzie, Alexander McSpaden, Wilfried Monange, Mark Nelson, Nicholas Thompson and Andrea Zoia, 1 July 2021, Nature Communications Physics.
DOI: 10.1038/s42005-021-00654-9

Funding: This work was supported by the DOE Nuclear Criticality Safety Program, funded and managed by the National Nuclear Security Administration for the Department of Energy.

Study reveals an increase in the frequency of nuclear power outages caused by climate change

by Ingrid Fadelli , Tech Xplore

Figure summarising climate-induced disruptions to the operation of nuclear power plants. Credit: Ahmad.

Past research suggests that climate change and energy systems have a bidirectional relationship. In other words, just like emissions from energy systems can fuel climate change, climate change could also expose the vulnerabilities or shortcomings of energy systems.

For instance, climate change could adversely impact the operation of critical energy systems and infrastructure, potentially disrupting the provision of electricity. While nuclear power plants (NPPs) could be a viable solution for generating low-carbon electricity, the operation of these plants is susceptible to climate change and to the extreme weather conditions resulting from it.

Ali Ahmad, a researcher at Harvard University, recently carried out a study investigating the possible effects of climate change on NPPs. His paper, published in Nature Energy, specifically assessed whether climatic changes over the past three decades impacted the frequency of nuclear power outages.

"With more than three decades of data on changing climate, we are now in a position to empirically assess the impact of climate change on power plant operations," Ahmad wrote in his paper. "Such empirical assessments can provide an additional measure of the resilience of power plants going forward. Here I analyze climate-linked outages in nuclear power plants over the past three decades."

Compared to other power plants, such as those based on fossil fuels and biomass, NPPs require stricter safety regulations. Moreover, after an unplanned outage, nuclear reactors need to undergo a series of tests and analyses aimed at identifying the issue, thus it can take a while before they are started again.

Understanding the extent to which climate change can impact the functioning of NPPs is thus of vital importance, as it could inspire the development of strategies to mitigate these climate-related effects. In his paper, Ahmad examined the frequency of climate-linked nuclear power outages over the past three decades or so.

Overall, he found that NPP outages caused by climatic events have become increasingly more frequent in the past few decades. Many of these outages were induced by changes in climate, while others were a result of natural disasters such as earthquakes or tsunamis. Ahmad screened available data to only focus on outages associated with climate change.

"My assessment shows that the average frequency of climate-induced disruptions has dramatically increased from 0.2 outage per reactor-year in the 1990s to 1.5 in the past decades," Ahmad wrote in his paper. "Based on the projections for adopted climate scenarios, the average annual energy loss of the global nuclear fleet is estimated to range between 0.8% and 1.4% in the mid-term (2046-2065) and 1.4% and 2.4% in the long term (2081-2100)."

As many researchers have been highlighting the value of nuclear power as a means to slow down and mitigate climate change, understanding the effects of climatic changes and global warming on NPPs before humans start heavily relying on them is of great importance. Ahmad's recent analyses demonstrate that the operation of NPPs was significantly disrupted by changes in climate over the past decades. In the future, the results of his study could help to create more realistic economic and nuclear energy models that take climate-associated risks into consideration.

Why nuclear energy isn't a safe bet in a warming world

More information: Increase in frequency of nuclear power outages due to changing climate. Nature Energy(2021). DOI: 10.1038/s41560-021-00849-y

Journal information: Nature Energy 

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