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How Scientists Actually Dismantle a Nuclear Bomb

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A Mark 28 thermo-nuclear bomb is unloaded from a U.S. Air Force Boeing B-52H Stratofortress aircraft. Credit: TSgt. Boyd Belcher, USAF)

(Inside Science) — There are enough nuclear weapons in the world to cause atomic Armageddon many times over, according to scientists, who estimate that no country could fire more than 100 nuclear warheads without wreaking such devastation that their own citizens back home would be killed.

Most nuclear nations recognized by the Treaty on the Non-Proliferation of Nuclear Weapons — namely, France, Russia, the United Kingdom and the United States — have set about reducing their arsenals. China is a notable exception. The exact number of the country’s warheads is unknown, but many analysts say its cache is slowly growing in size. North Korea, on the other hand, while notoriously difficult to predict, could eventually scale back its nuclear program if its diplomatic rapprochement with the West continues.

Negotiations on nuclear disarmament are politically tricky. But when agreements are reached, scientists and engineers can provide a variety of tools to take apart some of humanity’s most deadly weapons and store or repurpose the dangerous nuclear material. It’s a long and complex procedure, but experts say it’s one worth doing.

How to disassemble an armed “Swiss watch”

Nuclear disassembly is a coordinated process, which involves politicians, scientists and engineers working together.

It all begins with the blueprints that designers used to build the weapon in the first place, according to experts.

“It’s like any other kind of machine,” explained Robert Rosner, chair of the Bulletin of the Atomic Scientists Science and Security Board. “It’s a case of taking it apart piece by piece.”

To unpick a nuclear device, engineers need to know the exact sequence in which the pieces were originally put together.

“The design of atomic bombs is what I’d call an open secret. There aren’t that many ways of designing them and so if the Americans had to deal with the North Korean bombs, for example, it wouldn’t be much of a mystery to them,” said Rosner.

But the more sophisticated and destructive hydrogen bombs that the Americans, British, Chinese, French and Russians possess is a different story.

“There are many different designs and so the disassembly is very difficult. You have to be awfully careful,” said Rosner. “From a mechanical engineer’s perspective, they’re like a highly tuned Swiss watch. They’re mechanical artwork with amazingly clever designs.”

Other experts agree that unpacking the design is the most challenging part of the process.

“It’s less about the nuclear material and more about the engineering,” said Tom Plant, director of Proliferation and Nuclear Policy at the Royal United Services Institute for Defence and Security Studies, an independent think tank in the United Kingdom.

It would be significantly harder and therefore less likely that a team of engineers could disassemble a hydrogen bomb without knowing the exact design sequence, but still not technically impossible.

“It’s very unlikely that it would blow up if a mistake was made in the process of disassembly, unless it was designed to blow up in that eventuality, which is possible though not likely,” said Rosner.

Plant agrees the worst-case scenario is accidental detonation, but there are other possible perils if disassembly goes wrong. The people doing it could be electrocuted or exposed to the nuclear material or other toxic chemicals.

But a country, knowing its own design, should be able to disassemble its own modern nuclear weapons, and many have. As of 2014, the U.S. had dismantled 85 percent of its declared stockpile of nuclear weapons since 1967 when it had more than 31,000 war-ready nuclear warheads, according to the U.S. Department of State.

Before any nuclear dismantling can even take place, the right political atmosphere needs to exist, said Plant. He still isn’t optimistic that the current dialogue between Pyongyang and Washington has enough political will to see the Korean peninsular through to denuclearization. “The overwhelming likelihood is that everything falls apart as before.”

What do you do with the leftover uranium or plutonium?

Once the weapon has been taken apart, the process of dealing with what’s left is identical for both the older and the more sophisticated bombs.

“When the great powers decided to reduce their stockpiles, we were left with fairly substantial quantities of plutonium,” said Rosner. “So, what do you do?”

One obvious answer is to repurpose the radioactive material — either plutonium or uranium — to produce electricity. To make it suitable for a power plant, the material needs to be diluted with less enriched versions.

“There are no power reactors anywhere in the world that are designed to deal with weapons-grade material,” said Plant. “You have to down-blend it before you can turn it into fuel.”

But that isn’t what actually happens to most of the radioactive material.

“It’s not always economically viable. It can be cheaper to enrich new material than it is to downgrade it and repurpose it,” said Rosner. “Shipping plutonium or uranium all over the place from storage to reactor isn’t popular either.”

“Mostly it’s just stuck in storage facilities,” said Rosner.

Decommissioning the radioactive waste and keeping it safe is a science in its own right. The extracted uranium or plutonium will contain different isotopes — variants of themselves that have different atomic masses, which means their radioactivity decays at different rates.

The highly radioactive isotopes have short half-lives, which means they decay much faster than the less radioactive ones, and that creates a lot of heat.

“The material has to be put in water pools for about half a decade to cool the rods while they decay,” said Rosner. “Then you’re left with relatively low-level waste that’s less radioactive.”

The less radioactive isotopes are slower to decay, which presents its own problem.

“They have nuclei that are heavier, so they have very long half-lives of millions of years and you still have to do something with them. You can’t just leave them hanging around,” said Rosner.

The answer is to store the radioactive rods in specially designed containers, often called “dry casks.” These vessels are usually made from steel and welded shut to prevent leaking. Each of the casks is then encased in another steel shell and then in a thick layer of concrete to prevent radiation escaping.

“If you were standing outside of the container then you wouldn’t be able to detect radiation,” explained Rosner.

But even this containment option has its drawbacks — the cost of building, maintaining and monitoring these facilities will never go away so long as the rods inside are producing radiation. “That’s basically eternity for humans,” said Rosner.

Additionally, there’s national security to consider, said Plant. “Governments will be keeping it somewhere safe in case they want to reuse it or in case a terrorist tried to get hold of it.”

That’s why a third option has become more popular in recent years: partial disassembly.

After all, unless the bomb is detonated, the nuclear material inside is in a steady and contained state — partial disassembly keeps it there while removing the opportunity for the bomb to be used. “If you remover the trigger, then what’s left can’t be used as a bomb,” said Rosner.

But partial disassembly is reversible; the trigger can be put back in and the warhead can therefore be reactivated. “You couldn’t put it back in a matter of hours so they can’t be on standby. You’re talking about weeks to do it,” said Rosner.

If North Korea should ever agree to denuclearize, it has a few options to consider — none of them are perfect and all of them come with long-term strings attached, but when nuclear powers work together to control their arsenals, the world is a safer place, said Plant.

[This article originally appeared on InsideScience.org.]



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Pumped Milk Gives Infants Different Bacteria Than Breastfeeding, Study Says

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(Credit: Africa Studio/Shutterstock)

Mother’s milk provides sustenance for babies. Now researchers find pumped breast milk exposes newborns to more disease-causing bacteria than milk directly from the breast. The discovery suggests breastfeeding practices could shift the makeup of microorganisms in breast milk and infants’ digestive systems.

“We were surprised that the method of feeding was the most consistent factor associated with milk microbiota composition,” said Meghan Azad, a medical geneticist at the Children’s Hospital Research Institute of Manitoba in Canada, who led the new research.

Mighty Milk

Once considered sterile, researchers now know breast milk is full of bacteria. The microbes are thought to help set up infants’ digestive tracts with an ecosystem of microorganisms that will aid the growing human’s digestive and immune systems. Azad and her team were initially curious about this collection of bacteria in infants known as the infant gut microbiome. In an earlier study, they found breastfeeding affected babies’ gut bacteria the most. So, in the new research, the scientists probed the microbes in breast milk.

The researchers checked out the microbes in breast milk from nearly 400 nursing mothers and their three to four month old babies. The mommy-baby pairs are a part of a Canadian Healthy Infant Longitudinal Development birth cohort study known as the CHILD study, a long-term project looking to find the source of pediatric allergies. The researchers also looked at other elements — maternal age, smoking status and the microbes in babies mouths, to name a few — that could affect what bacteria are in breast milk.

Pumping Problem

The microbes in breast milk varied drastically between mothers, the researchers found, and both mom and baby mold the milk microbiome.

“Our results suggest that the infant’s oral bacteria are important in shaping the milk microbiota,” said Shirin Moossavi, a medical microbiology student in Azad’s lab, who authored the research.

But the biggest factor was whether babies received breast milk straight from the nipple or from a bottle. A family of bacteria that includes E. coli and salmonella were more abundant in pumped breast milk than direct breast milk, the researchers reported Wednesday in the journal Cell Host & Microbe.

“It is only in recent years that we have started to understand that there might be differences between direct nursing compared to feeding pumped milk,” Azad said.

“In the future, when we understand the mechanisms better, we might be able to provide recommendations about pump apparatus cleaning and milk storage to minimize the impact on the milk microbiota,” Moossavi added.

But no matter the delivery mode, “overall, breast milk is the best for the infant,” the researchers said.



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NASA Wants to Return to the Moon as Early as This Year

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NASA has big plans for returning to the moon, but private companies will do much of the work. (Credit: NASA)

In November, NASA tapped nine private spaceflight companies who will be allowed to bid on upcoming projects. Yesterday, they elaborated on what those projects would be during an industry forum. Starting as early as this year, NASA hopes to send commercial landers to the lunar surface as the first step toward returning to the moon, this time for good.

Long Lunar To-Do List

There’s a lot of work to be done before permanent or long-term lunar activities can begin. The first tasks will be to practice launching and landing on the moon, as well as answering questions about its surface. There’s plenty of technology NASA wants to see established on the ground before humans are sent back to the moon – and a lot of it is meant to stand in for future Mars settlement as well.

Some of that technology has to do with a recent buzzword among the space settlement community: in-situ resource utilization, or ISRU. This means using materials and resources already available on the moon and, one day, Mars, rather than carting all our resources with us, as has been standard for space missions. This most commonly means using solar power for energy. On the moon, it will also mean extracting water, which can be used for drinking or to power rockets. Both the hydrogen and oxygen that make up water are powerful fuel materials.

So commercial lunar partners will work on how to mine and recycle resources on the moon and make them available for future mission use. They will test habitation for future crewed missions. They’ll prove that they can collect materials from the lunar surface and return them to space or Earth. And they’ll establish communication networks between robots on the moon’s surface, way stations in lunar orbit, and mission control on Earth.

All these commercial endeavors would also need to integrate with NASA’s planned Lunar Gateway. This would be a space station in orbit around the moon that would serve as Grand Central Station for robotic or crewed missions to the lunar surface, or even for deep space missions. NASA hopes to open the Gateway by 2026, with the first power and propulsion elements entering orbit in 2022.



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Climate Change Hearings Signal Congress Is Willing to Address the Issue Again

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(credit: Roschetzky Photography/Shutterstock)

Climate change is real. It’s happening now. And it presents significant problems for the U.S. across multiple facets of society, according to a panel of climate and policy experts that testified before the House Science, Space and Technology Committee Wednesday in Washington, D.C.

The testimonials were part of the House Science Committee’s first full hearing of the 116th Congress and one of only a handful in the last eight years to address climate change. But that’s about to change. In her opening remarks, House Science Committee Chairwoman Eddie Bernice Johnson (D-TX) said Wednesday’s hearing will be the first of multiple hearings on climate change in the near future.

“Climate change is not just an environmental challenge,” said Robert Kopp, a climate scientist at Rutgers University in New Brunswick, New Jersey, during his testimony. “It’s an economic challenge, an infrastructure challenge, a public health challenge and a national security challenge.”

Carbon Cuts

For the most part, House representatives were in agreement with the panel that climate change is real and harming not only the environment but the economy and Americans. During the nearly two and half hours of questions that followed the researchers’ testimonies, representatives asked the scientists to identify priorities and sought their suggestions for solutions.

“Human emissions of CO2 must be brought as close to zero as possible with any continued emissions of CO2 balanced by human removal of carbon dioxide from the atmosphere,” said Kopp, who suggested expanding forests and using new, but little-tested technologies as a start. “The faster we reduce emissions, the less severe the effects and the lower the risk of unwelcome surprises,” he added.

Cities, states and a number of companies are already taking action by adopting emission reduction targets, but Kopp says these efforts need to grow dramatically and rapidly to effectively manage climate risk.

But Joseph Majkut, a policy expert with the Niskanen Center, a non-partisan think tank based in Washington, D.C., who also testified, acknowledged, “That’s a challenging thing to do.”

“To even get close, we’ll need significant innovation in low-carbon technology, finance and market design in order to be able to provide reliable, affordable and globally accessible low carbon energy,” Majkut said.

Majkut projected that to reach any temperature target, much less the 1.5 degrees C (2.7 degrees F) of warming goal set by the IPCC, would require carbon capture and storage of fossil fuels as well as carbon removal technologies in conjunction with renewable energy and storage solutions. He then advocated for research into alternatives to reducing global emissions, such as geoengineering technologies that would offset greenhouse gas production.

The scientists’ recommendations align with many facets of the Green New Deal Rep. Alexandria Ocasio-Cortex (D-NY) and Sen. Ed Markey (D-MA) recently proposed. The legislation calls for a massive policy shift that bolsters the U.S. economy and cuts greenhouse gas emissions to zero. Like the solutions Majkut outlined for the House Science Committee, the Green New Deal lists expanding and upgrading renewable energy sources, removing greenhouse gases from the atmosphere and increasing carbon storage as ways to achieve its goal.

Rep. Ralph Norman (R-SC) and others raised concerns about the cost of such an initiative, asking “If the Green New Deal were implemented immediately, wouldn’t it devastate our economy?” But, says Majkut, reducing CO2 associated with economic activity is “one of the cheapest elements” of the bill.

Adaptive Measures

The scientists testifying before the House also recommended prioritizing research into the ways society might adapt to climate change and called on federal support for studies of how climate change will affect communities, a research topic Kristie Ebi, an epidemiologist at the University of Washington in Seattle, is already looking into.

Ebi, another scientist to testify at the hearing, investigates how climate change affects human health. Researchers have discovered Americans are already suffering and dying from climate change and the impacts will likely only get worse.

“Risk from vector-borne diseases such as malaria, Dengue fever and Lyme disease are projected to increase with warming from 1.5 to 2 C (2.7 to 3.6 F) including potential shifts in their geographic range to areas previously unexposed to these diseases,” Ebi said. “Further, our healthcare infrastructure is vulnerable to extreme events with, for example, many hospitals and healthcare clinics located in coastal regions subject to flooding.”

Yet, there are achievable ways to alleviate the projected risks and costs associated with climate change’s impacts on communities, Ebi said, such as “developing early notification response plans for extreme heat … and incorporating climate projections into emergency preparedness and disaster risk management initiatives.”

“These steps can protect health now and provide a basis for effective adaptation to our future climate,” she added.

And if the world does not slow the rise of greenhouse gas emissions, Americans’ health and the U.S. economy will suffer because of impacts associated with mortality and the ability of people to work outdoors, scientists say. More extreme weather events will also affect human health and the economy.

“We know that in 2018, the losses due to extreme weather were roughly $160 billion just to the U.S.,” said Jennifer Francis, an atmospheric scientists at the Woods Hole Research Center in Falmouth, Massachusetts, during her testimony. “But what keeps me up at night is thinking about my own daughter and the world she will face if we do nothing.”



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