nuclear power

Planned nuclear fuel has higher proliferation risks than thought

Energy, nuclear power, nuclear proliferation, Science, uranium / Ryan Harris / June 10, 2024

A lump of rock, next to the periodic table entry for uranium, all against a black background.

High-assay low-enriched uranium (HALEU) has been touted as the go-to fuel for powering next-gen nuclear reactors, which include the sodium-cooled TerraPower or the space-borne system powering Demonstration Rocket for Agile Cislunar Operations (DRACO). That’s because it was supposed to offer higher efficiency while keeping uranium enrichment “well below the threshold needed for weapons-grade material,” according to the US Department of Energy.

This justified huge government investments in HALEU production in the US and UK, as well as relaxed security requirements for facilities using it as fuel. But now, a team of scientists has published an article in Science that argues that you can make a nuclear bomb using HALEU.

“I looked it up and DRACO space reactor will use around 300 kg of HALEU. This is marginal, but I would say you could make one a weapon with that much,” says Edwin Lyman, the director of Nuclear Power Safety at the Union of Concerned Scientists and co-author of the paper.

Forgotten threats

“When uranium is mined out of the ground, it’s mostly a mixture of two isotopes: uranium-238 and uranium-235. Uranium 235 concentrations are below one percent,” says Lyman. This is sent through an enrichment process, usually in gas centrifuges, where it is turned into gaseous form and centrifuged till the two isotopes are separated from each other due to their slight difference in their atomic weights. This can produce uranium with various levels of enrichment. Material that’s under 10 percent uranium-235 is called low-enriched uranium (LEU) and is used in power reactors working today. Moving the enrichment level up to between 10 and 20 percent, we get HALEU; above 20 percent, we start talking about highly enriched uranium, which can reach over 90 percent enrichment for uses like nuclear weapons.

“Historically, 20 percent has been considered a threshold between highly enriched uranium and low enriched uranium and, over time, that’s been associated with the limit of what is usable in nuclear weapons and what isn’t. But the truth is that threshold is not really a limit of weapons usability,” says Lyman. And we knew that since long time ago.

A study assessing the weaponization potential of uranium with different enrichment levels was done by the Los Alamos National Laboratory back in 1954. The findings were clear: Uranium enriched up to 10 percent was no good for weapons, regardless of how much of it you had. HALEU, though, was found to be of “weapons significance,” provided a sufficient amount was available. “My sense is that once they established 20 percent is somewhat acceptable, and given the material is weapons-usable only when you have enough of it, they just thought we’d need to limit the quantities and we’d be okay. That sort of got baked into the international security framework for uranium because there was not that much HALEU,” says Lyman. The Los Alamos study recommended releasing 100 kg of uranium enriched to up to 20 percent for research purposes in other countries, as they didn’t think 100 kg could lead to any nuclear threats.

The question that wasn’t answered at the time was how much was too much.

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Why Germany ditched nuclear before coal—and why it won’t go back

coal, germany, nuclear power, Science, syndication / Ryan Harris / April 28, 2024

Enlarge / Jürgen Trittin, member of the German Bundestag and former environment minister, stands next to an activist during an action of the environmental organization Greenpeace in front of the Brandenburg Gate in April 2023. The action is to celebrate the shutdown of the last three German nuclear power plants.

One year ago, Germany took its last three nuclear power stations offline. When it comes to energy, few events have baffled outsiders more.

In the face of climate change, calls to expedite the transition away from fossil fuels, and an energy crisis precipitated by Russia’s 2022 invasion of Ukraine, Berlin’s move to quit nuclear before carbon-intensive energy sources like coal has attracted significant criticism. (Greta Thunberg prominently labeled it “a mistake.”)

This decision can only be understood in the context of post-war socio-political developments in Germany, where anti-nuclearism predated the public climate discourse.

From a 1971 West German bestseller evocatively titled Peaceably into Catastrophe: A Documentation of Nuclear Power Plants, to huge protests of hundreds of thousands—including the largest-ever demonstration seen in the West German capital Bonn—the anti-nuclear movement attracted national attention and widespread sympathy. It became a major political force well before even the Chernobyl disaster of 1986.

Its motivations included: a distrust of technocracy; ecological, environmental, and safety fears; suspicions that nuclear energy could engender nuclear proliferation; and general opposition to concentrated power (especially after its extreme consolidation under the Nazi dictatorship).

Instead, activists championed what they regarded as safer, greener, and more accessible renewable alternatives like solar and wind, embracing their promise of greater self-sufficiency, community participation, and citizen empowerment (“energy democracy”).

This support for renewables was less about CO₂ and more aimed at resetting power relations (through decentralised, bottom-up generation rather than top-down production and distribution), protecting local ecosystems, and promoting peace in the context of the Cold War.

Germany’s Energiewende

The contrast here with Thunberg’s latter-day Fridays for Future movement and its “listen to the experts” slogan is striking. The older activist generation deliberately rejected the mainstream expertise of the time, which then regarded centralised nuclear power as the future and mass deployment of distributed renewables as a pipe dream.

This earlier movement was instrumental in creating Germany’s Green Party—today the world’s most influential—which emerged in 1980 and first entered national government from 1998 to 2005 as junior partner to the Social Democrats. This “red-green” coalition banned new reactors, announced a shutdown of existing ones by 2022, and passed a raft of legislation supporting renewable energy.

That, in turn, turbocharged the national deployment of renewables, which ballooned from 6.3 percent of gross domestic electricity consumption in 2000 to 51.8 percent in 2023.

These figures are all the more remarkable given the contributions of ordinary citizens. In 2019, they owned fully 40.4 percent (and over 50 percent in the early 2010s) of Germany’s total installed renewable power generation capacity, whether through community wind energy cooperatives, farm-based biogas installations, or household rooftop solar.

Most other countries’ more recent energy transitions have been attempts to achieve net-zero targets using whatever low-carbon technologies are available. Germany’s now-famous “Energiewende” (translated as “energy transition” or even “energy revolution”), however, has from its earlier inception sought to shift away from both carbon-intensive as well as nuclear energy to predominantly renewable alternatives.

Indeed, the very book credited with coining the term Energiewende in 1980 was, significantly, titled Energie-Wende: Growth and Prosperity Without Oil and Uranium and published by a think tank founded by anti-nuclear activists.

Consecutive German governments have, over the past two and a half decades, more or less hewed to this line. Angela Merkel’s pro-nuclear second cabinet (2009–13) was an initial exception.

That lasted until the 2011 Fukushima disaster, after which mass protests of 250,000 and a shock state election loss to the Greens forced that administration, too, to revert to the 2022 phaseout plan. Small wonder that so many politicians today are reluctant to reopen that particular Pandora’s box.

Another ongoing political headache is where to store the country’s nuclear waste, an issue Germany has never managed to solve. No community has consented to host such a facility, and those designated for this purpose have seen large-scale protests.

Instead, radioactive waste has been stored in temporary facilities close to existing reactors—no long-term solution.

Why Germany ditched nuclear before coal—and why it won’t go back Read More »

40% of US electricity is now emissions-free

coal, Energy, hydroelectric, natural gas, nuclear power, renewable energy, Science, solar, Sustainability, Wind / Blake Jones / December 29, 2023

Decarbonizing, but slowly —

Good news as natural gas, coal, and solar see the biggest changes.

John Timmer – Dec 28, 2023 7: 12 pm UTC

Image of electric power lines with a power plant cooling tower in the background.

Just before the holiday break, the US Energy Information Agency released data on the country’s electrical generation. Because of delays in reporting, the monthly data runs through October, so it doesn’t provide a complete picture of the changes we’ve seen in 2023. But some of the trends now seem locked in for the year: wind and solar are likely to be in a dead heat with coal, and all carbon-emissions-free sources combined will account for roughly 40 percent of US electricity production.

Tracking trends

Having data through October necessarily provides an incomplete picture of 2023. There are several factors that can cause the later months of the year to differ from the earlier ones. Some forms of generation are seasonal—notably solar, which has its highest production over the summer months. Weather can also play a role, as unusually high demand for heating in the winter months could potentially require that older fossil fuel plants be brought online. It also influences production from hydroelectric plants, creating lots of year-to-year variation.

Finally, everything’s taking place against a backdrop of booming construction of solar and natural gas. So, it’s entirely possible that we will have built enough new solar over the course of the year to offset the seasonal decline at the end of the year.

Let’s look at the year-to-date data to get a sense of the trends and where things stand. We’ll then check the monthly data for October to see if any of those trends show indications of reversing.

The most important takeaway is that energy use is largely flat. Overall electricity production year-to-date is down by just over one percent from 2022, though demand was higher this October compared to last year. This is in keeping with a general trend of flat-to-declining electricity use as greater efficiency is offsetting factors like population growth and expanding electrification.

That’s important because it means that any newly added capacity will displace the use of existing facilities. And, at the moment, that displacement is happening to coal.

Can’t hide the decline

At this point last year, coal had produced nearly 20 percent of the electricity in the US. This year, it’s down to 16.2 percent, and only accounts for 15.5 percent of October’s production. Wind and solar combined are presently at 16 percent of year-to-date production, meaning they’re likely to be in a dead heat with coal this year and easily surpass it next year.

Year-to-date, wind is largely unchanged since 2022, accounting for about 10 percent of total generation, and it’s up to over 11 percent in the October data, so that’s unlikely to change much by the end of the year. Solar has seen a significant change, going from five to six percent of the total electricity production (this figure includes both utility-scale generation and the EIA’s estimate of residential production). And it’s largely unchanged in October alone, suggesting that new construction is offsetting some of the seasonal decline.

Enlarge / Coal is being squeezed out by natural gas, with an assist from renewables.

Eric Bangeman/Ars Technica

Hydroelectric production has dropped by about six percent since last year, causing it to slip from 6.1 percent to 5.8 percent of the total production. Depending on the next couple of months, that may allow solar to pass hydro on the list of renewables.

Combined, the three major renewables account for about 22 percent of year-to-date electricity generation, up about 0.5 percent since last year. They’re up by even more in the October data, placing them well ahead of both nuclear and coal.

Nuclear itself is largely unchanged, allowing it to pass coal thanks to the latter’s decline. Its output has been boosted by a new, 1.1 Gigawatt reactor that come online this year (a second at the same site, Vogtle in Georgia, is set to start commercial production at any moment). But that’s likely to be the end of new nuclear capacity for this decade; the challenge will be keeping existing plants open despite their age and high costs.

If we combine nuclear and renewables under the umbrella of carbon-free generation, then that’s up by nearly 1 percent since 2022 and is likely to surpass 40 percent for the first time.

The only thing that’s keeping carbon-free power from growing faster is natural gas, which is the fastest-growing source of generation at the moment, going from 40 percent of the year-to-date total in 2022 to 43.3 percent this year. (It’s actually slightly below that level in the October data.) The explosive growth of natural gas in the US has been a big environmental win, since it creates the least particulate pollution of all the fossil fuels, as well as the lowest carbon emissions per unit of electricity. But its use is going to need to start dropping soon if the US is to meet its climate goals, so it will be critical to see whether its growth flat lines over the next few years.

Outside of natural gas, however, all the trends in US generation are good, especially considering that the rise of renewable production would have seemed like an impossibility a decade ago. Unfortunately, the pace is currently too slow for the US to have a net-zero electric grid by the end of the decade.

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