Sunday, December 18, 2022

Oregon city drops fight to keep Google water use private

by Andrew Selsky

Residents of The Dalles, Oregon, are learning how much of their water Google's data centers have been using to cool the computers inside the cavernous buildings—information that previously was deemed a trade secret.

Google says its data centers in the Oregon town consumed 274.5 million gallons (1 billion liters) of water last year. Dawn Rasmussen, who lives on the outskirts of The Dalles and has seen the level of her well water drop year after year, said she is shocked.

"I'm flabbergasted and I'm scared for the future," Rasmussen said. "As we continue to be in drought conditions and the natural water table continues to get depleted, then the city itself is going to start to struggle."

Data centers around the world help people stream movies, store trillions of photos and conduct daily business online, but a single facility can churn through hundreds of thousands of gallons of water per day.

The California-based company has plans to potentially build more data centers in The Dalles, and that worried some residents who fear there eventually won't be enough water for everyone—including for area farms and fruit orchards, by far the biggest users.

A lawsuit by the city on behalf of Google—against Oregon's biggest newspaper, The Oregonian/OregonLive—that sought to keep the water-use information confidential was dropped, the newspaper reported Thursday.

City officials abandoned the 13-month legal fight and committed to release the company's water consumption in future years.

In an email, Google confirmed Thursday that its water use numbers would no longer be a trade secret.

"It is one example of the importance of transparency, which we are aiming to increase ... which includes site-level water usage numbers for all our U.S. data center sites, including The Dalles," Google spokesperson Devon Smiley said.

In a Nov. 21 blog posting, Google said that all of its global data centers consumed approximately 4.3 billion gallons (16.3 billion liters) of water in 2021, which it said is comparable to the water needed to irrigate and maintain 29 golf courses in the southwest U.S. each year.

John DeVoe, executive director of WaterWatch of Oregon, a conservation organization, said there should be no secrecy about these numbers.

He said Google's data centers in The Dalles used enough water in 2021 to cover the city's entire 7 square miles (18 square kilometers) 3 inches (7.6 centimeters) deep.

The Dalles Mayor Richard Mays said Google had previously insisted its water usage was a trade secret because the company was concerned about competitors knowing how it cools its servers, but then changed its position and agreed to release the water records.

"That's why we backed off (the lawsuit)," Mays told The Oregonian/OregonLive.

The Oregonian/OregonLive, which had requested Google's records last year, said the case represents a major test of Oregon public records law.

"This seemed to be a perfect example of a clash of two important storylines, both the expansion of big businesses and the public resource that they need to use," Therese Bottomly, editor of The Oregonian/OregonLive, was quoted as saying.

Mays and Public Works Director Dave Anderson did not immediately respond to requests for further comment.

Google has been considering building two new data centers in The Dalles. The town lies along the mighty Columbia River, but the new data centers wouldn't be able to use that water and instead would have to take water from rivers and groundwater that has gone through the city's water treatment plant.

Communities in the West have been grappling with a more than 20-year megadrought that studies link to human-caused climate change. The snowpack in the nearby Cascade Range that feeds the aquifers varies wildly year-to-year and glaciers are melting.

Town councilors voted unanimously in November 2021 to approve Google's proposal to build two new data centers, even though the 15,000 town residents didn't know how much water the proposed data centers would use. Even the town councilors themselves had to wait until a couple of weeks before the vote to find out the projected usage numbers.

"Water is a public resource," DeVoe said. "The public deserves to know how much water is used—and from what sources—by those who take water from rivers and streams and pump water from aquifers."

The U.S. hosts 30% of the world's data centers, more than any other country. Some data centers are trying to become more efficient in water consumption, for example by recycling the same water several times through a center before discharging it.

A study published last year by researchers at Virginia Tech and Lawrence Berkeley National Laboratory showed one-fifth of data centers rely on water from moderately to highly stressed watersheds.

Under the settlement filed Wednesday with Wasco County Circuit Court, The Dalles will pay $53,000 to cover the legal costs for Reporters Committee for Freedom of the Press, a nonprofit group that represented the newspaper. The city said Google will cover its own legal costs of $106,000 and has committed to covering the $53,000 settlement.

City OKs Google data centers amid secrecy, water worries

Study identifies most likely locations for semiconductor plants in US

by Ball State University

The passage of the Creating Helpful Incentives to Produce Semiconductors (CHIPS) Act has led to widespread enthusiasm regarding the possibility of increased manufacturing of semiconductors in the United States.

With the likelihood of the U.S. experiencing growth in the manufacturing of semiconductors, researchers at Ball State University have pinpointed the locations across the country most likely to experience expansion of semiconductor chip production in the coming years.

"Semiconductor Plant Location Decisions in the Wake of the CHIPS Act," a recently published study from Ball State's Center for Business and Economic Research (CBER), identifies 83 U.S. counties, sorted into three tiers, in which new plant locations are most likely. The study was co-authored by CBER researchers Dr. Michael Hicks and Dr. Dagney Faulk.

"The CHIPS Act offers incentives to increase the potential for growth in domestic semiconductor manufacturing," Dr. Hicks said. "Combined with the costly disruptions of chip production during COVID-19, it is especially likely the United States will see new semiconductor production. Where that production will occur is of substantial policy interest across much of the nation."

The CBER study combines data from the Semiconductor Industry Association, the U.S. Census Bureau, the Bureau of Economic Analysis, secondary studies, and other private sources to model the potential locations of semiconductor manufacturing firms.

Among the more important variables in explaining the expansion of the semiconductor industry are the educational attainment of the workforce (bachelor's degree or higher), the share of residents in graduate school, population growth, and high unexplained productivity (generalized agglomerations).

The "Tier 1" metropolitan areas considered most likely to be considered for a new semiconductor plant, according to the CBER study, are: Boulder, Colo., Chicago, Ill.; Columbus, Ohio; Dallas-Fort Worth-Arlington, Texas; Denver-Aurora-Lakewood, Colo.; Houston-The Woodlands-Sugarland, Texas; Madison, Wisc.; Miami-Dade County, Fla.; New York-Northern New Jersey-Long Island; San Diego-Carlsbad, Calif.; Seattle-Tacoma-Olympia, Wash.; and St. Louis, Mo.

The report also identifies 20 Tier 2 and 17 Tier 3 potential plant locations, which are considered "likely" and "somewhat likely" compared to Tier 1.

"Tier 1 locations are the most likely places to be selected for new semiconductor manufacturing facilities," Dr. Faulk said. "These locations all possess sufficiently large numbers of available workers and are large metropolitan areas with multiple suitable counties or at least one very suitable county for expansion."

The study also compared its results to a separate list of new proposed plants reported to the Semiconductor Industry Association; out of those 20 locations, the CBER model correctly predicts 18 of them. The two locations not included in the CBER study—West Lafayette, Ind., and Midland Metropolitan Area-Bay City, Mich.—both nearly met the researchers' inclusion criterion.

Though the U.S. currently manufactures a large share of the world's microconductors (microchips), recent widespread supply disruptions caused significant production delays in automobiles, appliances and consumer electronics.

The CHIPS Act of 2022 provides substantial funding and incentives for semiconductor and related firms to locate, upgrade, and expand within the United States. The Act provides $52.7 billion in emergency supplemental appropriations. The largest share, $50.0 billion over five years, is used to establish a CHIPS for America Fund to provide funding for provisions authorized in the FY2021 National Defense Authorization Act.

These provisions required the development of domestic semiconductor manufacturing capability, research and development, and workforce training programs. The largest share is allocated to legacy chip production, which is essential to the military, automotive, and other industries.

Provided by Ball State University Biden to attend groundbreaking of Intel's $20B Ohio plants

COVID restrictions may have contributed to increase in RSV infections

by Matt Kristoffersen, Yale University

Annual spikes in infections from the respiratory syncytial virus—or RSV—are usually so predictable that "you can set your clock" by it, says Yale School of Public Health Associate Professor of Epidemiology (Microbial Diseases) Daniel Weinberger.

Normally a cold-weather epidemic, RSV usually spreads among young children, straining hospitals in the Northern Hemisphere as early as late October and lasting until the cold and flu season wanes in spring.The COVID-19 pandemic appears to have upended this rhythm in one country and possibly others.

Weinberger, together with YSPH Ph.D. student Zhe Zheng, Associate Professor Virginia Pitzer, ScD, and an international team of researchers, recently published a study suggesting that a surge of RSV infections began in the Netherlands last summer and has lingered in the country ever since.

The pre-print study, published on medRxiv and produced collaboratively among epidemiologists in the U.S., France, and the Netherlands, has yet to be peer-reviewed. But its findings show that non-pharmaceutical interventions which were used to stop the spread of COVID-19, like social distancing and school closures, may have helped create a so-called "immunity debt" that is impacting children today.

"We saw all around the world that RSV basically disappeared [during COVID]—it's one of the most common causes of hospitalization in young patients, and it was completely eliminated for over a year, which was really remarkable," Weinberger said. "Our colleagues in the Netherlands had the foresight when this unusual pattern started to put excellent surveillance into place to monitor the occurrence of RSV around the country."

The change in infection rates isn't entirely a bad thing, Weinberger cautions. Even though RSV-related hospitalizations are now climbing in the United States and abroad, the fact that many children are being exposed to the illness later in life could lead to less severe infections overall.

"We have seen an age shift in the RSV epidemic recently," Weinberger said. "Kids that were coming in this year and last year are on average a little bit older than the kids who were coming in before the pandemic, and we think that's partially because they've never been exposed before. That's actually better because older kids are less susceptible to very severe outcomes from RSV."

As part of their analysis, the Dutch team, led by Professor Louis Bont, collected real-time pediatric RSV illness data from 46 hospitals across the Netherlands from May 2021 to September 2022. Combined with existing surveillance data on RSV illnesses by patient age, and analyzed with mathematical models, their analysis revealed an "unusual" RSV epidemic pattern within the country, the study's authors said.

Graphs in their paper show a dagger-like spike in RSV infections almost immediately following the end of a COVID-19 lockdown period in June 2021, followed by a prolonged period of continuous transmission of RSV at mid-to-high levels through July 2022.

These occurrences may be partially explained by waning population immunity, the researchers write—an "immunity debt"—which the Netherlands is only now catching up on.

"Normally, you're exposed to RSV during the winter and your immunity gets boosted a little bit as you get re-exposed and your immune system gets recharged," Weinberger said. "But we had this long period where people weren't getting exposed, where we had more people who had never seen RSV, and also people who hadn't seen RSV in a long time who were more susceptible to infections. A combination of those things, we think, led to this sustained transmission of RSV over quite a long period."

The researchers concede their study has limitations. For one, some hospitals in the Netherlands did not consistently give the researchers data. And the data that they received was not always standardized. The researchers write in their paper that these issues may have led to an underestimation of the number of RSV-related illnesses in the country.

Still, good news might be coming. Weinberger said that—based on the current data—the United States could be on the tail end of its RSV epidemic for this season. And RSV's seasonal cycles may return to their clock-like reliability by next winter, the researchers predict, as herd immunity to RSV infections goes back to what it was before the pandemic.

"Based on our models, we can expect that we are going to return to a regular seasonal pattern in the pretty near future," he said. "We can already see that happening in the Southern Hemisphere, where they are just now coming out of the winter, where countries seem to be returning to a more regular cycle of RSV."

More information: Yvette N. Löwensteyn et al, Year-round RSV Transmission in the Netherlands Following the COVID-19 Pandemic—A Prospective Nationwide Observational and Modeling Study, medRxiv (2022). DOI: 10.1101/2022.11.10.22282132

Provided by Yale University

COVID, flu, RSV: How this triple threat of respiratory viruses could collide this winter

CRIMINAL CRYPTO CAPITALI$M

Bogus 'Bitcoin killer' cryptocurrency founder pleads guilty

A co-founder of the fraudulent cryptocurrency OneCoin, a pyramid scheme that conned billions of dollars from investors worldwide, pleaded guilty to wire fraud and money laundering charges, U.S. prosecutors said Friday.

Touted as a "Bitcoin killer," prosecutors said the purported cryptocurrency co-founded by Ruja Ignatova and Karl Sebastian Greenwood in 2014 in Bulgaria was actually worthless. Though marketed as a cryptocurrency, it was never mined using computers and there was no public and verifiable blockchain. The value of OneCoin was not set by supply and demand, but by its operators, they said.

Greenwood, 45, was arrested at his island residence in Thailand in 2018 and extradited to the United States. He pleaded guilty Friday in federal court in Manhattan.

Greenwood, a citizen of Sweden and the United Kingdom, has been detained since his arrest.

U.S. Attorney Damian Williams said Greenwood helped operate one of the largest international fraud schemes in history. His office said victims invested more than $4 billion.

"Greenwood's lies were designed with one goal, to get everyday people all over the world to part with their hard-earned money—real money—and to line his own pockets to the tune of hundreds of millions of dollars," Williams said in a statement.

Ignatova, nicknamed the Cryptoqueen and described as OneCoin's top leader, disappeared in October 2017 and remains at large. In June, she was added to the FBI's Top Ten Most Wanted List and there is a $100,000 reward for information leading to her arrest.

OneCoin's growth was fueled by multilevel marketing, in which members received commissions for recruiting others to purchase cryptocurrency packages.

Though Ignatova boasted that OneCoin would be "the Bitcoin killer," she and Greenwood referred to it as "trashy coin" in email correspondence. In one email, Greenwood referred to investors as idiots.

Greenwood pleaded guilty to one count of conspiracy to commit wire fraud, one count of wire fraud and one count of conspiracy to commit money laundering. Each count carries a maximum sentence of 20 years in prison.

He will be sentenced April 5.

2 Estonians arrested in $575M cryptocurrency fraud

Possible new ways to continue growing coffee in a changing climate

A team of authors from Uganda and the U.K. with backgrounds in botany, agriculture and the coffee industry has published an article in the journal Nature Plants, pointing out that that the world's coffee growers may soon have to find new ways to grow the popular bean plant due to climate change. In their paper, the group outlines three possible choices facing coffee growers and their preferred option.

Farmers are among those likely to be affected by climate change. In this new effort, the researchers looked at the impact climate change is already having on coffee bean production. They note that in some places where coffee bean plants grow, temperatures are changing and rainfall is becoming less stable. And that, they further note, puts production of coffee beans at risk.

Job Mweru Walubiri [Coffee Technician, Kyagalanyi Coffee Ltd.] inspecting the drying of excelsa coffee at the farm of Nsobya Yusuf (Uganda). Credit: Aaron Davis

Unripe fruits of ‘traditional’ large-fruited Liberica coffee. Credit: Aaron Davis

The researchers found that coffee growers are almost certainly going to have to make adjustments to the way they grow their beans. They suggest that there are three main options: They can move to more suitable areas, change how they tend their plants or switch to different coffee bean plant varieties. The researchers suggest the third option is the most viable.

Currently, most of the world drinks coffee made from either arabica or robusta coffee beans. And over the past several years, yields have decreased for both as droughts have limited production in many areas. To keep the coffee flowing, the researchers suggest coffee growers consider switching to Liberica coffee bean plants.

They note that the variety has been tested at a number of sites and has been found better able to withstand more variable weather conditions. They also note that the beans stay on the plants after maturing, which makes harvesting easier.

The researchers acknowledge that switching has its drawbacks—the beans have tougher skin, for example, which will make processing them more difficult. They can also start to ferment if not harvested as soon as they ripen, which ruins the taste of the coffee. But the researchers conclude that the switch is worth it because, in the coming years, farmers may find it impossible to grown enough arabica beans to suit demand.

More information: Aaron P. Davis et al, The re-emergence of Liberica coffee as a major crop plant, Nature Plants (2022). DOI: 10.1038/s41477-022-01309-5

Journal information: Nature Plants

Stromboli's 'rejuvenation' heralds era of more variable volcanic eruptions

by James Ashworth, Natural History Museum

An unexpected series of eruptions at Stromboli may be due to changes in the volcano's internal "plumbing."

Changes to the layer separating the volcano's reservoirs are allowing deeper magma to rise more quickly, which can trigger violent and unpredictable blasts.A volcano that has been erupting almost constantly for thousands of years may be becoming more erratic.

Stromboli volcano, which lies on an island of the coast of Sicily, Italy, has fascinated scientists for centuries, and is one of the most researched and monitored volcanoes in the world.

However, a series of eruptions and violent blasts known as paroxysms in 2019 took everyone by surprise. New research suggests that the volcano's internal 'plumbing' system may have changed, allowing magma from deep beneath the surface to rise more easily.

Dr. Chiara Maria Petrone, an expert in volcanoes at the Museum and the lead author of a new study detailing these changes, says, "The rejuvenation of Stromboli's magma pathways has clear implications for the monitoring of the volcano.

"We need to develop a high frequency petrological monitoring system to tell us what is happening deeper in the volcano, not just what is happening at the surface."

The findings of the study were published in the journal Nature Communications.

Strombolian eruptions

Stromboli is a basaltic volcano, which is one of the most common types on Earth. These volcanoes generally erupt effusively, meaning that gas can easily escape from the magma chamber so that the magma escapes as lava flows.

Stromboli is close to a number of villages, making monitoring of the volcano a priority.

Stromboli, however, is different from other basaltic volcanoes. It gives its name to a style of eruption characterized by short, explosive bursts that generate plumes which can reach hundreds of meters into the air and occur relatively regularly.

They are caused by gas bubbles bursting at a shallow depth in the magma, which throws the magma out of the volcano and creates a lava fountain.

Sometimes, more violent eruptions can occur. Major explosions are eruptions which tend to be a more intense version of a Strombolian eruption, and occur four to five times a year at Stromboli.

Paroxysms, meanwhile, are larger blasts that last for a short period of time, and are much more infrequent. Stromboli's paroxysms can also be associated with pyroclastic flows of hot gases and debris, and also with tsunamis if they cause a lot of rock to fall down the mountain and into the sea.

In 2019, however, there was an unusual combination of a major explosion followed by two paroxysms in the space of two months which no one had anticipated.

"The activity in 2019 was very unexpected," Chiara says. "All the monitoring signals suggested there Stromboli was more lively than normal, but it remained within the range of expected levels."

"Even after the major explosion, none of the parameters were really abnormal, and so the two paroxysms weren't detected until just before they were about to take place."

Following the first paroxysm, Chiara applied for urgent research funding to investigate what was taking place at Stromboli, and to explain why these events were taking place.

How is Stromboli changing?

While double paroxysms are not unheard of, they are very uncommon. To find out what might be responsible, Chiara and her fellow researchers looked at minerals known as pyroxenes.

Paroxysms, like that pictured from 3 July 2019, are violent bursts of volcanic activity.

They compared the composition and texture of samples taken from Stromboli's previous eruptions in 2003 to 2017, as well as those from the 2019 eruptions. By examining how these minerals differed, they could gain an insight into the inner workings of the volcano.

"There are two main ways paroxysms are triggered," Chiara explains. "There is a bottom-up model, where magma from the deeper reservoir shoots up into the shallow reservoir without any chemical mixing taking place, which can cause a paroxysm."

"The other model is a top-down model, with lava draining out of the shallow reservoir decompressing the top chamber. The resulting reduction in pressure allows the deeper magma to rise quickly without mixing with the shallow system."

While it was previously thought that lava flow was a signal of an upcoming paroxysm, the researchers found that the 2019 Stromboli paroxysms were both driven by the arrival of magma from the deep reservoir.

It began arriving in the system in the months leading up to the paroxysms, picking up in the month before the first and continuing until the second occurred.

Chiara and her co-authors have attributed this to changes in the volcano's crystal mush, which forms from the partial crystallization of magma.

"We know that there is a well-developed mush at Stromboli," Chiara says. "In previous paroxysms, we found that some of the minerals from this layer were carried to the surface as the deeper magma passed through it and into the shallower system."

"However, this wasn't the case in 2019. We think that there is probably a more direct link between the deeper and shallower reservoirs caused by the magma permeating the crystal mush more fully, allowing magma to rise more frequently. This could explain why the activity of the volcano has become more variable."

The team have called for the analysis of newly-erupted rocks to be sped up, so that researchers can better understand how volcanoes have changed over time.

"There were records of multiple paroxysms in Stromboli's past, but we just didn't realize that at the time," Chiara says. "We need to better know the development of its volcanic system, as knowing how it behaved in the past allows us to better interpret the present."

More information: Chiara Maria Petrone et al, Magma recharge and mush rejuvenation drive paroxysmal activity at Stromboli volcano, Nature Communications (2022). DOI: 10.1038/s41467-022-35405-z

Journal information: Nature Communications

Provided by Natural History Museum

This story is republished courtesy of Natural History Museum. Read the original story here

Mitigating corrosion by liquid tin could lead to better cooling in fusion reactors

Peer-Reviewed Publication

TOKYO INSTITUTE OF TECHNOL

Fig. 1 (a) Tin tableware, (b) Liquid metal fluid, (c) Mechanism of liquid metal divertor and corrosion issues — IMAGE: - view more
CREDIT: MASATOSHI KONDO

Researchers at Tokyo Institute of Technology and the National Institute for Fusion Science have clarified the chemical compatibility between high temperature liquid metal tin (Sn) and reduced activation ferritic martensitic, a candidate structural material for fusion reactors. This discovery has paved the way for the development of a liquid metal tin divertor, which is an advanced heat-removal component of fusion reactors. A device called a divertor is installed in the fusion reactors to maintain the purity of the plasma. For divertors, there has been demand for liquid metals that can withstand extremely large heat loads from high-temperature plasma.

Background

Fusion reactors are being actively developed throughout the world as a form of sustainable zero-carbon energies because their fuel can be extracted from an inexhaustible supply of seawater. Also, they do not emit greenhouse gases. In addition to the construction of the tokamak (ITER), which is being constructed through collaboration of seven of the world's leading countries and regions (Japan, EU, United States, South Korea, China, Russia, and India), fusion development by the private sector is also accelerating.

One of the most important components in these fusion reactors is the divertor, a component which gasifies impurities in the plasma and sends the gas to an exhaust pump. During operation of a fusion reactor, some of the structural components of the divertor are exposed to extremely large heat loads at the same level as the “space shuttle when entering the atmosphere.” Researchers are working to develop a solid divertor in which a block of heat-resistant material such as tungsten is placed in contact with the plasma and cooled with high-temperature, high-pressure water. This solid divertor system is also used in the ITER project and the prototype fusion reactors. Conversely, as an innovative mechanism to withstand the large heat load from plasma, researchers have also considered the concept of a liquid metal divertor which protects the divertor from plasma by covering the structural material of the divertor with a liquid metal that possesses excellent cooling performance.

As shown in Fig. 1(a), tin (Sn) is a metal that has been used in various ways in our daily lives; for example, as a material for tableware and as a component of solder. Tin has a relatively low melting point of 232°C and is suitable for use in a liquid state as shown in Fig. 1(b). Another property of tin is that its vapor pressure at high temperatures is lower than that of other liquid metals. Therefore, as shown in Fig. 1(c), when liquid metal tin is used as a coolant to cover and protect the structural material surface of the liquid metal divertor of a fusion reactor, it is difficult to evaporate even if it is heated by plasma and reaches a high temperature. It also possesses the advantage of the evaporated metal being less likely to mix with the plasma. However, the corrosion of structural materials is a technical issue that has been concerned by researchers.

(a) When immersed in liquid tin at 500°C for 25 hours. (b) When immersed

in liquid tin at 500°C for 250 hours. Taken using a scanning electron microscope.

Fig.3 Image of cross-section of surface layer corrosion structure of oxide sinter immersed in liquid metal tin (IMAGE)

TOKYO INSTITUTE OF TECHNOLOGY

(a) When a sintered body of iron oxide (Fe2O3) was immersed in liquid tin at 500°C for 262 hours. (b) When a sintered body of chromium oxide (Cr2O3) was immersed in liquid tin at 500°C for 262 hours. Images obtained using a scanning electron microscope.
CREDIT
Masatoshi Kondo

Research results

Kondo's laboratory has focused on chemical coexistence with various structural and functional materials. The laboratory has given particular attention to liquid metal coolants attracting attention in the field of next-generation energy such as fusion reactors. Researchers concentrated on liquid metal tin, which reveals the inconvenient property of being highly reactive at high temperatures. They worked to clarify the corrosion mechanism of fusion reactor structural materials and to discover materials that exhibit corrosion resistance.

1. What is high-temperature liquid metal tin and what causes its intense corrosiveness?

Reduced activation ferritic martensitic (Fe-9Cr-2W-0.1C), which is the primary candidate structural material for fusion reactors, is based on the composition of ferritic martensitic heat-resistant steel. Reduced activation ferritic martensitic uses additive elements that reduce induced radioactivity, assuming use in a neutron irradiation environment in a reactor. When reduced activation ferritic martensitic steel comes into contact with liquid metal tin, the incubation period before corrosion begins is very short. As shown in Figures 2(a) to 2(b), the researchers determined that the steel contains iron (Fe) which reacts with high-temperature tin to corrode the material while rapidly forming intermetallic compounds (FeSn2, etc.) on the tin. In addition to containing iron, reduced　activation ferritic martensitic steel also contains elements such as chromium and tungsten that do not easily react with tin. Therefore, the steel has a lower corrosion rate than that of pure iron. However, after ten days at 500°C, the steel forms an intermetallic compound with a thickness of about 155 micrometers and corrodes. When extrapolating these numbers to one year, the thickness could reach the order of millimeters, which is a very large corrosion rate. At 600°C, the researchers found that thinning due to corrosion became even more severe. At this time, the researchers also found that corrosion progresses due to the inward diffusion of tin into the microstructure of the steel.

Associate Professor Masatoshi Kondo of Tokyo Institute of Technology, who leads the research team, gave the following explanation: “Although liquid metal tin is an excellent coolant with a variety of properties, it has the drawback of corroding structural materials. By clarifying the corrosion mechanism, we hope to promote the use of liquid metal tin not only for fusion energy but also for solar thermal power plants.”

2. What materials can withstand high-temperature liquid metal tin at high temperatures?

The researchers found that steel/iron-based structural materials corrode outwardly and inwardly while forming intermetallic compounds when exposed to high-temperature liquid metal tin. This is because iron, the main component of steel, reacts with high-temperature liquid tin. Therefore, the researchers theorized that it would be possible to prevent reaction with high-temperature tin by combining the iron with oxygen in advance to form an oxide prior to the reaction. Pursuing this theory, the researchers tested iron oxide (Fe2O3) and chromium oxide (Cr2O3) for compatibility with liquid tin at 500°C. The results are shown in Figure 3. When immersing the iron oxide sintered material, tin partially penetrated into the pores that were created during firing. However, the thickness of the reaction structure with tin on the material surface was about 1 micrometer. This was an extremely thin reaction which is only about 1% that of reduced activation ferritic steel. Moreover, when examining the sintered material of chromium oxide, it can be seen that the reaction structure with tin on the surface is very thin. In this way, the researchers found that even a metal element such as iron, which easily reacts with tin, can be significantly suppressed by prior reaction with oxygen to form an oxide.

“The operating environment of a liquid tin divertor in a fusion reactor is under extremely harsh conditions in which corrosion by liquid tin and irradiation of fusion neutrons are superimposed,” explained Professor Kondo, who leads research by the Japanese team in Task 3 of the U.S.-Japan Science and Technology Cooperation Program: FRONTIER Project). “In this project, we are collaborating with the project team members from Oak Ridge National Laboratory in the United States to investigate the effects of radiation on the corrosion reaction dynamics of steel with liquid tin, “he added.

The discoveries discussed in this article clarified the cause and mechanism of corrosion of liquid metal tin, which has relatively strong corrosiveness. This research will contribute significantly to the achievement of a carbon-neutral society by assisting in the development of highly reliable advanced heat-receiving equipment for fusion reactors.

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Selecting the right structural materials for fusion reactors | Tokyo Tech News

Research video: Liquid Metal, Shaping the World | Tokyo Tech News

Sustainable construction using eco-friendly concrete: Press webinar with Assoc. Prof. Masatoshi Kondo | Tokyo Tech News

Kondo Laboratory

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About Tokyo Institute of Technology

Tokyo Tech stands at the forefront of research and higher education as the leading university for science and technology in Japan. Tokyo Tech researchers excel in fields ranging from materials science to biology, computer science, and physics. Founded in 1881, Tokyo Tech hosts over 10,000 undergraduate and graduate students per year, who develop into scientific leaders and some of the most sought-after engineers in industry. Embodying the Japanese philosophy of “monotsukuri,” meaning “technical ingenuity and innovation,” the Tokyo Tech community strives to contribute to society through high-impact research.

https://www.titech.ac.jp/english/

About National Institute for Fusion Science

Aiming at the early achievement of fusion energy, the National Institute for Fusion Science（NIFS）is advancing its research activities in fusion plasma and other targets in fields of experimental research using the Large Helical Device (LHD), theory and simulation, and fusion engineering. NIFS is also playing an active role in mutual cooperation with universities and research organizations in Japan and abroad, and is producing excellent researchers.

https://www.nifs.ac.jp/en/

DOI

10.1016/j.corsci.2022.110748

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Corrosion mechanism of reduced activation ferritic martensitic steel JLF-1 in liquid metal Sn

LA REVUE GAUCHE - Left Comment