Does wood bioenergy help or harm the climate?

"To avoid the worst harms from climate change we must
not only keep the vast majority of remaining fossil carbon
in the ground, but must also keep the vast majority of the
carbon in forests on the land."

In the most financially successful version of biomass technology to date, huge swathes of forests in North America are clearcut and all the vegetation ground and compressed into dense little chips that look like the feed pellets available at the corner pet store. After it’s been processed into these generic pellets, the wood is relatively easy to use as a replacement for coal: the wood (or any other organic material) is made to behave as much as possible like very small, broken-up pieces of coal in a furnace. Logs and wood pellets 

image courtesy of VisionTIR

LONG READ

By John Sterman, William Moomaw, Juliette N. Rooney-Varga, Lori Siegel, 

May 10, 2022

In the 2015 Paris climate accord, 197 countries agreed to limit warming to “well below 2 degrees Celsius,” and to strive for 1.5 degrees Celsius. To have even a roughly 50 percent chance of achieving this goal, net global greenhouse gas emissions must be cut by nearly half from 2010 levels this decade and reach zero by mid-century (UNFCCC 2021). Consequently, at least 140 countries, accounting for about 90 percent of global greenhouse gas emissions, have pledged to reach net zero emissions around the middle of this century (Climate Action Tracker 2021). But few have specified how they will do so. A growing number, including the European Union, the United Kingdom, and the United States, have declared wood bioenergy to be carbon neutral, allowing them to exclude the carbon dioxide generated from wood bioenergy combustion in their greenhouse gas accounting. Many subsidize wood bioenergy to help meet their renewable energy targets (Norton et al. 2019). The appeal is intuitive: burning fossil fuels adds carbon that has been sequestered underground for millions of years to the atmosphere, while forests might regrow, eventually removing carbon dioxide from the atmosphere.

But can burning trees—including not just the trunk, but also the bark, branches, needles or leaves, roots, stumps, mill waste, sawdust, and all the other vegetative materials known as “biomass” that make up a forest—help cut carbon emissions in time to prevent climate catastrophe?

The bioenergy industry and many governments argue that wood bioenergy is carbon neutral. The “Claims and Facts” tables throughout the text below list some of the common claims the industry makes, together with the science showing these claims to be incorrect. For example, the UN Food and Agriculture Organization claims that “While burning fossil fuels releases CO2 that has been locked up for millions of years, burning biomass simply returns to the atmosphere the carbon dioxide that was absorbed as the plants grew” (Matthews and Robertson 2001). But the fact that the carbon in wood was previously removed from the atmosphere as the trees grew is irrelevant: A molecule of carbon dioxide added to the atmosphere today has the same impact on radiative forcing—its contribution to global warming—whether it comes from fossil fuels millions of years old or biomass grown last year. When burned, the carbon in those trees immediately increases atmospheric carbon dioxide above what it would have been had they not been burned.



To illustrate, consider a forest that was harvested for lumber, pulpwood, or energy 50 years ago, and has been regrowing since then. (Few forests in the United States and Europe are mature, “old growth”—most are “working forests” and go through cycles of harvest, regrowth, and reharvest [see US Forest Service 2014]). What happens if that forest is now cut and burned for energy? When the wood is burned, the carbon it contains is emitted as carbon dioxide into the atmosphere. If the forest regrows, after another 50 years it will have removed about the same amount of carbon dioxide it emitted when it was cut and burned for energy. Until then, there’s more carbon dioxide in the atmosphere than if it had not been burned, accelerating climate change.

But the situation is worse: If the forest had not been cut, it would have continued to grow, removing additional carbon from the atmosphere. Compared to allowing the forest to grow, cutting it for bioenergy would increase carbon dioxide emissions and worsen global warming for at least half a century—time we do not have to reach net-zero emissions and avoid the worst harms from climate change.

But what if the wood used to generate electricity reduces the use of fossil fuels? Wouldn’t total carbon dioxide emissions then fall? That depends on how much carbon dioxide is emitted from wood relative to the fuel being displaced. To determine whether wood bioenergy can slow climate change, we therefore need to know answers to a series of questions:

How much carbon dioxide does burning wood for energy add to the atmosphere?

Burning wood to generate electricity emits more carbon dioxide per kilowatt-hour generated than fossil fuels—even coal, the most carbon-intensive fossil fuel. Although wood and coal contain about the same amount of carbon per unit of primary energy—the raw energy in the fuel—(EPA 2018), wood burns less efficiently, in part because it contains more water than coal. The higher the water content, the larger the fraction of the energy of combustion goes into vaporizing that water and up the flue instead of producing the heat needed to make the steam that powers the turbines and generators (Dzurenda and Banski 2017, FAO 2015).

Carbon dioxide emissions from the wood supply chain also exceed those from coal. Wood must be harvested, transported to a mill, dried, processed into chips or pellets, and transported to a power plant (Figure 1). These activities emit carbon dioxide from fossil fuel-powered vehicles and machinery, plus emissions from burning wood or fossil fuels to reduce the water content of chips and pellets from approximately 50 percent for raw wood to about 10 percent for dried pellets. About 27 percent of the harvested biomass is lost in the wood pellet supply chain, of which the largest share—18 percent—arises from burning some of the biomass to generate heat to dry pellets (Röder et al. 2015). In contrast, coal processing adds only about 11 percent to emissions (Sterman et al. 2018a).

The situation is worse if wood displaces other fossil fuels: Wood releases about 25 percent more carbon dioxide per joule of primary energy than fuel oil, and about 75 percent more carbon dioxide than fossil (so-called “natural”) gas (EPA 2018). Wood bioenergy therefore emits more carbon dioxide per kilowatt-hour of power generated than all fossil fuels, including coal (PFPI 2011), incurring a “carbon debt”—an immediate increase in carbon dioxide in the atmosphere, worsening climate change every year, unless and until that carbon debt is repaid later by forest regrowth. 

Figure 1. Life cycle emissions from wood bioenergy. Every stage of the supply chain adds CO2 to the atmosphere, from cutting the trees through transport, processing the wood into chips or pellets, transporting them to a power plant, and combustion. CO2 is removed only later, and only if, the harvested land regrows. Photo credits, left to right: Power Plant, courtesy of Paul Glazzard, Creative Commons Attribution-ShareAlike 2.0 license. Transport: Handymax bulk carrier, courtesy of Nsandel/Wikimedia/Public Domain. Pellet mill, Truck Transport, and Forest images all courtesy of Dogwood Alliance, used with permission.

Will the forests harvested for bioenergy regrow? If so, how long will it take?

The wood bioenergy industry claims to practice sustainable forestry and be carbon neutral (e.g., Drax 2021, Enviva 2021). The most important claim is that wood bioenergy is carbon neutral because the harvested forests will regrow, removing the carbon they add to the atmosphere when burned (Table 1). However, regrowth is uncertain, and regrowth takes time.

Regrowth is uncertain: Land harvested for bioenergy might be converted to pasture, cropland, or development, preventing regrowth. The carbon dioxide emitted when the trees are burned is then never taken back up by forest regrowth on that land. Even if the harvested land is allowed to regrow, the trees may be harvested again, legally or illegally. The carbon dioxide released in each rotation returns to the atmosphere, where it worsens climate change.

Even if the recovering forest is somehow protected against all future harvest, the trees face risks from wildfire, insects, disease, extreme weather, and drought, all increasing as the climate warms (Brecka et al. 2018; Xu et al. 2019, Boulton, Lenton and Boers 2022). These factors slow or prevent carbon dioxide removal from the atmosphere by forests and may even convert forests from carbon sinks to carbon sources (Gatti et al. 2021). These growing risks to regrowth would limit the future removal of the carbon dioxide emitted by burning wood, permanently worsening climate change.

Regrowth takes time: Even if land conversion, repeated harvests, fire, drought, disease, and other adverse events never arise, regrowth takes time. The time required for regrowth to remove the carbon dioxide emitted when wood is burned for energy is known as the “carbon debt payback time.”


Are the forests harvested for bioenergy growing and removing carbon dioxide now?

The US bioenergy industry uses the fact that many US forests are growing today to claim that wood bioenergy is carbon neutral. For example, Enviva, the largest US pellet producer, with multiple mills in the Southeast United States, falsely argues that “…continued forest carbon gain across the landscape… means that products from the Southeast U.S., including wood bioenergy, are not adding carbon emissions to the atmosphere. As a result, when wood pellets from this region are used to generate energy, we can set stack emissions to zero.” (Enviva, nd; see Table 1).
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It is true that forests in the Southeast US are acting as carbon sinks today as the result of intensive management and recovery from prior harvests. But these and other forest carbon sinks are already accounted for in the national greenhouse gas emissions inventories required under the United Nations Framework Convention on Climate Change, which sets the rules for greenhouse gas accounting under international agreements (e.g., UNFCCC 2014). Therefore, what counts is what happens to emissions on the margin—that is, the incremental impact of harvesting forests for bioenergy compared to allowing those forests to continue to grow and serve as carbon sinks. Typical rotation periods for working forests are far shorter than the time required for them to reach maturity and maximum carbon storage (Moomaw, Masino, and Faison 2019, Sohngen and Brown 2011, US Forest Service 2014). The younger the forest and faster it is growing when harvested for bioenergy, the more future carbon sequestration is lost.

A dynamic lifecycle assessment of wood bioenergy

To determine the impact of wood bioenergy on carbon dioxide emissions we developed a model for dynamic lifecycle assessment of wood bioenergy (Sterman et al. 2018a; Sterman et al. 2018b). The model includes carbon dioxide emissions from bioenergy, carbon dioxide uptake by regrowth, and carbon dioxide emissions avoided if wood displaces fossil fuels. Supply chain emissions for both wood and fossil fuels are included. Model parameters were estimated from data on forest regrowth in a wide range of forests in the southern and eastern USA, regions increasingly supplying wood for pellets, much of which is exported to Europe and the United Kingdom.

Figure 2. Impact of harvesting wood for bioenergy in 2025 from a 50-year-old oak-hickory forest in the south central USA. Top: Change in carbon on the harvested land (tons C per hectare). Brown: carbon in soils and dead organic matter; Green: carbon in living biomass. Dotted line: the total carbon stock (living biomass and soils) if the forest were not harvested in 2025. The forest would have continued to grow and remove carbon from the atmosphere but for being cut for bioenergy. The difference between the dotted no-harvest line and the top of the green band is the carbon emitted into the atmosphere by the harvest. Bottom: Change in atmospheric CO2 resulting from the harvest and combustion of the wood. Solid line: wood displaces a zero-carbon energy source. Dotted line: wood displaces coal. Scale: the initial rise in atmospheric CO2 when wood displaces zero-carbon energy is normalized to 100%. The initial rise in atmospheric CO2 when wood displaces coal is about 50% less due to the emissions avoided by the reduction in coal use.

Figure 2 (above) shows the impact of wood harvested for bioenergy from an oak-hickory forest, “perhaps the most extensive deciduous forest type of eastern North America” (Dick 2016). The simulation parameters are estimated for oak-hickory forests in the south central United States, among the forests used to supply wood pellets for bioenergy, including exports to the United Kingdom (Buchholz & Gunn 2015; Sterman et al. 2018a 2018b report results for other forests in the southern and eastern US). Most forests in the United States have been cut multiple times. We assume the last prior harvest was 50 years ago. To assess the dynamic impact of wood bioenergy use, Figure 2 traces the impact of a single harvest in 2025, showing the stocks of carbon in the biomass and soil and the resulting change in the concentration of carbon dioxide in the atmosphere. We consider two scenarios:The harvested wood is used to generate electric power that replaces an equivalent amount of energy generated from coal, the most carbon-intensive fossil fuel.
The harvested wood is used to generate electric power that replaces an equivalent amount of energy produced by zero-carbon sources (e.g., wind and solar).

The top panel of Figure 2 shows the stock of carbon on the land harvested for bioenergy (metric tons of carbon per hectare), including the carbon in the living biomass and in soils and dead organic matter. The harvest and combustion of wood for energy immediately reduces the stock of carbon in living biomass on the land and increases atmospheric carbon dioxide. The stock of carbon in dead biomass and soil also begins to drop: the wood harvest reduces the flux of carbon from living biomass to soils, while heterotrophic respiration by bacteria, fungi, and other organisms continues to release the carbon in dead biomass and soils into the atmosphere. After the harvest, the forest begins to recover. Soil carbon continues to drop for some time, however, until the flux of carbon transferred to the soils from living biomass exceeds the flux of carbon emitted to the atmosphere from the soil by heterotrophic respiration.

The simulation assumes the land is harvested 50 years after the last rotation. The forest at that time is still recovering. The dotted line in the top panel of Figure 2 shows that the total stock of carbon on that land would have continued to grow through 2200 (and beyond), but for the harvest for bioenergy. The difference between the no-harvest and harvest cases is the quantity of carbon lost to the atmosphere due to the bioenergy harvest. The bioenergy harvest not only adds the carbon extracted and burned to the atmosphere, but prevents the additional growth that would have occurred had the forest not been harvested.

The bottom panel of Figure 2 shows the change in the concentration of carbon dioxide in the atmosphere for the two scenarios above. The figure shows the evolution of atmospheric carbon dioxide relative to the no-harvest case, scaled relative to the magnitude of the initial change in carbon dioxide when the wood displaces zero-carbon energy such as wind and solar (the absolute change in atmospheric carbon dioxide depends on the amount of wood harvested and burned). Cutting and burning trees for bioenergy immediately increases the concentration of carbon dioxide in the atmosphere. The jump in atmospheric carbon dioxide when wood displaces coal is approximately half as much as when the wood displaces zero-carbon energy. The impact of displacing other fossil fuels such as fuel oil or fossil (“natural”) gas lies between the coal and zero-carbon scenarios because these fuels emit less carbon dioxide per kilowatt-hour than coal, but of course more than wind or solar.

Note that, in both cases atmospheric carbon dioxide continues to increase through approximately 2040, 15 years after the assumed harvest in 2025. Although the harvested land begins to regrow immediately, seedlings and saplings have much smaller leaf area for photosynthesis and accumulate carbon slower than older trees. Consequently, the carbon sequestered by regrowth is initially less than the carbon the forest would have stored had it not been harvested.


After approximately the year 2040, the excess carbon dioxide in the atmosphere from the harvest and combustion of the wood begins to fall as regrowth outpaces the growth in carbon in the no-harvest case. However, atmospheric carbon dioxide remains above the level it would have had but for the harvest well beyond the year 2100. Even when wood displaces coal, the excess carbon dioxide is not taken back up by forest regrowth until after the year 2140: The carbon debt payback time in this scenario is approximately 115 years. When the wood displaces zero-carbon energy, atmospheric carbon dioxide remains above its initial level well past the year 2200.

The simulation shows the impact of clearing a stand of forest and using the wood for bioenergy. The bioenergy industry claims that they practice what they call “sustainable” forestry—avoiding clearcutting, taking only residues from lumber and pulpwood harvests, or thinning forests by taking only small or diseased trees. Environmental groups, however, have documented the harvest of large trees and clear-cutting by the industry (Norton et al. 2019; Stashwick et al. 2019; Stashwick et al. 2017). To address this issue, we also simulated the impact of thinning, in which only 25 percent of the living biomass is removed from the harvested forest (Sterman et al. 2018a 2018b). Across all the forests examined, thinning reduces the carbon debt payback times somewhat. For example, in the scenario shown in Figure 2, thinning reduces the carbon debt payback year from 2140 to 2115—still too late.

The simulations favor wood bioenergy. We assume that the land remains forested, that the forest grows back without any subsequent harvest, and that it suffers no losses from wildfire, disease, insects, extreme weather or other threats to regrowth. We do not consider additional carbon loss from soils due to the disturbance caused by the harvest. We do not consider non-climate harms from wood harvest and bioenergy production, including habitat fragmentation, loss of biodiversity, and the health effects of exposure to particulates and other pollutants from wood processing and power plants.

To track the impact of wood bioenergy, the simulation shows the impact of harvesting and burning wood for energy in a single year. But the bioenergy industry is growing rapidly, stimulated by the false declaration that wood is carbon neutral and resulting subsidies in many nations. The International Energy Agency reports primary energy from biomass for electricity generation grew at an average rate of more than 6 percent per year between 1990 and 2018 (IEA 2020). The IEA’s “Net-Zero by 2050” scenario projects modern bioenergy—which includes wood—will grow by more than a factor of four by 2050 (IEA 2021b).

What happens to atmospheric carbon dioxide in the realistic case of growing wood bioenergy use? Each year the carbon dioxide emissions from cutting and burning wood would exceed the removal of carbon dioxide by regrowth, continually increasing the concentration of carbon dioxide in the atmosphere, just as filling your bathtub faster than it drains will continually raise the level of water in the tub (until it overflows and damages your home).

The situation is analogous to a government that runs a continually growing fiscal deficit. The outstanding debt rises every year even if the government fully repays every bond it issues at maturity. In the same way, the growing use of wood bioenergy adds more carbon dioxide to the atmosphere every year, increasing the outstanding carbon debt, even if the forests are managed sustainably and all harvested lands eventually recover enough to fully repay the carbon debt incurred when the wood was extracted and burned.


Eventual carbon neutrality is not climate neutrality

Even under the best case where wood displaces coal, regrowth does not remove the excess carbon dioxide emitted by wood for many decades or more, and far longer if the harvested forests are growing today—as most are—and far more if wood displaces other fossil fuels. At that future time, wood bioenergy can be said to have achieved carbon neutrality. Until then, wood bioenergy increases the level of carbon dioxide in the atmosphere above what it would have been, accelerating global warming.

But is the climate impact of that additional warming reversed if regrowth finally removes the excess carbon dioxide? Is eventual carbon neutrality the same as climate neutrality?

The answer is “No.”

Even temporarily elevated levels of atmospheric carbon dioxide cause irreversible climate damage (IPCC 2022; Solomon et al. 2009). The excess carbon dioxide from wood bioenergy begins warming the climate immediately upon entering the atmosphere. The harms caused by that additional warming are not undone even if the carbon debt from wood energy is eventually repaid: The Greenland and Antarctic ice sheets melt faster, sea level rises higher, wildfires become more likely, permafrost thaws faster, and storms intensify more than if the wood had not been burned. Eventual full forest recovery will not replace lost ice, lower sea level, undo climate disasters, put carbon back into permafrost, or bring back homes lost to floods or wildfires. The excess warming from wood bioenergy increases the chances of going beyond various climate tipping points that could lead to runaway climate change: emissions “pathways that overshoot 1.5°C run a greater risk of passing through ‘tipping points’, thresholds beyond which certain impacts can no longer be avoided even if temperatures are brought back down later on” (IPCC 2018, p. 283). Carbon neutrality is not climate neutrality.

Why does it matter? We have already raised global average surface temperatures about 1.1 degrees Celsius (2 degrees Fahrenheit) above preindustrial levels, and most of humanity already suffers from its effects (Callaghan et al. 2021, IPCC 2022). The consequences of warming beyond 2 degrees Celsius are expected to be devastating. Sea levels could rise by well over a meter by the end of this century, exposing millions of people to coastal flooding (Kulp & Strauss 2019). More than half the world’s people would be exposed to deadly heat waves (Mora et al. 2017). The yields of crops including wheat, maize, rice, and soy would fall even as the United Nations projects that world population will grow by billions (Zhao et al. 2017, United Nations 2019). Droughts, wildfires, and intense storms will become more frequent and extreme (IPCC 2018). Warming could push the Earth beyond various tipping points that could lead to irreversible harm (IPCC 2018). These impacts would intensify hunger, economic disruption, mass migration, civil conflict, and war (Burke et al. 2015; Hsiang & Burke 2014; Koubi 2019; Levy 2019). Scientists and nearly all nations on Earth therefore agree that global greenhouse gas emissions must fall as deeply and quickly as possible, reaching net zero by approximately midcentury.

Wood bioenergy moves the world in the wrong direction.

Policy implications

What can be done? First, policies that treat wood bioenergy as carbon neutral must end. These policies allow power plants and nations to ignore the carbon dioxide they emit by burning wood on the false assumption that those emissions are quickly offset by forest growth somewhere else, creating a “critical climate accounting error” (Searchinger, et al. 2009). The carbon dioxide emitted from wood should be counted the same way emissions from other fuels are: fully, at the point of combustion.

Second, subsidies for wood bioenergy must end. Subsidizing wood bioenergy means taxpayers are paying pellet and power producers to make climate change worse.

Third, the fact that wood bioenergy is worse than coal in no way justifies the continued use of coal or any fossil fuel. To avoid the worst harms from climate change we must not only keep the vast majority of remaining fossilized carbon in the ground, we must also keep the vast majority of the carbon in our forests on the land.

The good news is that existing technologies such as energy efficiency, and the use of renewables such as solar, wind, and geothermal energy, can meet people’s needs for comfort, light, mobility, communication, and other purposes. The costs of these technologies are falling rapidly, and in many places are already lower than fossil fuels (IEA 2021a). Innovations in clean energy, energy storage, smart grids, and other technologies are expanding our ability to meet everyone’s energy needs affordably. Unlike wood bioenergy, these technologies allow forests to continue growing and sequestering atmospheric carbon dioxide. Investments in energy efficiency and clean energy also generate multiple co-benefits including increased community resilience, jobs, and improved health and economic well-being, especially for low-income individuals and households (Belesova et al. 2020; Burke et al. 2018; IEA 2021a; IPCC 2018; Pollin et al. 2014; Shindell et al. 2018). In contrast, particulate emissions and other pollutants from wood bioenergy damage human health (Allergy & Asthma Network et al. 2016).

To keep global warming under 2 degrees Celsius, net greenhouse gas emissions must fall to net zero by approximately mid-century, less than 30 years from now. Wood bioenergy increases greenhouse gas emissions and makes climate change worse during these critical years and beyond, even if the wood displaces coal. More effective ways to cut greenhouse gas emissions and meet human needs are available and affordable now. Ending subsidies and policies that promote wood bioenergy will reduce emissions and allow forests to continue to grow, preserving their vital role as carbon sinks that moderate climate change.

Disclosure Statement

No potential conflict of interest was reported by the authors.

Funding

Authors John Sterman and Lori Siegel received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors for this work. Author William Moomaw was supported by a grant from the Rockefeller Brothers Foundation. Author Juliette N. Rooney-Varga was supported by the National Science Foundation under grant ICER-1701062.


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Brazil wants special treatment for its nuclear submarine program—just like Australia


By Ian J. Stewart | June 28, 2022

The Brazilian Navy’s first Scorpène-class submarine S40 Riachuelo, launched in
December 2018. The first Brazilian nuclear-powered attack submarine SSN Alvaro Alberto is scheduled for 2030.

On June 6, Brazil and the IAEA entered into negotiations over safeguards (known as special procedures) to allow the largest South American country to use nuclear fuel in its slow-burning submarine program. Coming alongside a collective effort by the United States, the United Kingdom, and Australia (known as the AUKUS security framework) to transfer nuclear-powered submarines to Australia, this means that two non-nuclear weapons states are now negotiating with the IAEA over safeguards provisions for submarines. Although the two cases evolve within different security contexts, with AUKUS being squarely aimed at countering China, this new development will complicate the negotiations over how to safeguard nuclear material used in submarines.

Two sides of the same coin. The 2021 announcement about AUKUS focused attention for the first time in recent history on the question of how to safeguard nuclear fuel for submarines in a non-nuclear weapons state. Under AUKUS, the three countries are spending 18 months examining how to transfer nuclear submarines to Australia without undermining nonproliferation efforts. While much remains unclear, nuclear weapons-grade, highly-enriched uranium (HEU) fuel imported by Australia for its submarine reactors will likely arrive as “sealed” reactors. Under AUKUS, Australia will not acquire the prerequisite nuclear fuel cycle steps such as uranium enrichment. Because of these provisions, many would argue the direct proliferation risks brought by AUKUS are low. The fissile material will be irradiated in a reactor, which would make it radioactive and thus harder to handle. Removing the fuel would disable the submarine. And Australia anyway does not have the facilities to open the reactor, remove the irradiated fuel, and use it to make nuclear weapons.

Despite this, the prospects of normalizing HEU for use in non-nuclear weapons state submarine programs alarm many. Furthermore, China is furious about the AUKUS announcement, recognizing that it is entirely aimed at countering China from a geostrategic perspective. Diplomatically, and as rearticulated to the author in interviews earlier this year, China has focused much of its fury on raising concerns about the proliferation risks of AUKUS and the precedent it could set for other countries. As a way of building diplomatic pressure on AUKUS, China has called for a standing agenda item on the IAEA board of governors related to safeguards and for a “criteria-based” approach to safeguard designs for submarines.


In this context, Brazil’s initiative takes on its full meaning. Brazil’s submarine program has been under development for decades and is not likely to come to fruition any time soon. However, Brazil seems to appreciate that whichever submarine safeguards agreement is negotiated first will set a precedent for others. Brazil’s decision to launch special procedure negotiations therefore may come from hopes that whatever safeguards approaches agreed upon in the AUKUS case won’t be detrimental to Brazil’s interests. In another twist, whereas China’s proposed criteria-based approach may be just a diplomatic tool to stop Australia from accessing HEU, others may join China’s effort in proposing a criteria-based approach whose purpose is more than just pressing Australia

Brazil’s nonproliferation policy challenge. The Brazil and Australia approaches are scarcely comparable. Whereas Australia seeks to import turnkey reactors from either the United States or the United Kingdom, Brazil is taking an entirely different, indigenous path by developing its own civilian and military nuclear fuel cycles, the latter being geared toward its submarine program. Brazil is expected to use low-enriched uranium (LEU) fuel in the submarines which in principle should be of little concern as LEU is not suitable for weapons. However, given Brazil has an indigenous military nuclear fuel cycle, including uranium conversion and enrichment facilities, proliferation concerns will be high. Brazil is also building a prototype submarine reactor. From interviews with relevant officials earlier this year, the author understands that Brazil intends to manufacture uranium metal for future iterations of its submarines. The interviews suggested that Brazil intends to ask to place nearly all of its military nuclear fuel cycle, under special procedures. This would be an incredibly broad request that would set off alarm bells in many countries.

There are even more complexities in the Brazil case. The country has not yet concluded an additional protocol with the IAEA. Brazil also is a party to the quadripartite safeguards agreement which gives both the IAEA and the Brazilian-Argentine Agency for Accounting and Control of Nuclear Material (ABACC) a role in safeguarding the submarine program. The absence of an additional protocol is likely to be seen as incompatible with having a military nuclear fuel cycle and advancing submarine program. Because of this incompatibility, Brazil is expected to explore the conclusion of an additional protocol as part of the special procedure negotiations—which would be already an important development. Brazil has historically been one of the main holdouts to universalizing the additional protocol. Based on interviews with leading figures in the negotiation of the Treaty on the Prohibition of Nuclear Weapons (TPNW), Brazil is also considered to be in large part responsible for the limited safeguards-based verification measures associated with the TPNW concluded in 2020, which does not require countries to conclude an additional protocol with the IAEA. The conclusion of an additional protocol by Brazil may thus allow scope for discussion on strengthening the verification provisions associated with the TPNW. The prospect of Brazil concluding an additional protocol and the advancement of Brazil’s submarine program means that ABACC would also have to evolve. It is understood that ABACC is also expected to take on some additional protocol-like provisions in its own safeguards system. Brazil’s decision to start negotiations on the safeguards provisions of its submarine program is likely to have profound implications for the ABACC safeguards regime.


Coming: complex negotiations on nuclear submarine safeguards. The net result is that 2022 will mark the beginning of complex negotiations on safeguards for nuclear submarines that will have important implications for the safeguards system. Besides the issue of safeguarding submarine fuel, Brazil’s special procedure negotiations may also affect the future of ABACC. Importantly, it may also lead Brazil to conclude an additional protocol with the IAEA which, thanks to the quadripartite safeguards agreement, would likely see Argentina do the same. Two of the main countries with substantial nuclear fuel cycles but still without an additional protocol could thus be on the verge of concluding them, which might renew momentum towards its universalization.

Much remains unclear however as to whether Brazil’s announcement will result in the creation of a criteria-based approach to submarine safeguards. It is difficult to see how a single criterion could apply to the very different nuclear fuel paths being pursued by Australia and Brazil. While some may argue that such a criterion should exclude the possibility of using HEU fuel in submarines, it is not clear how banning HEU use and relying instead on LEU with an associated indigenous nuclear fuel cycle is a lower risk option from a nonproliferation perspective. Perhaps a common ground criterion for all countries pursuing nuclear-powered submarines should be to have in place an additional protocol with the IAEA. In this regard, at least, the precedent set by Australia and Brazil can be positive.


Ian J. Stewart is executive director of the James Martin Center in Washington, DC. He previously worked in the UK Ministry of Defence where, among other... Read More

Interview: Small modular reactors get a reality check about their waste

By François Diaz-Maurin | June 17, 2022

An artist's rendering of NuScale Power's small modular nuclear reactor plant.
Photo courtesy of NuScale

Even before Chernobyl’s RBMK reactor became the standard design of the Soviet Union, it was known to have inherent safety flaws but kept unchanged because it was “cheaper” that way. Historians later found that more than economic and technical considerations, it was social, regulatory, political, and cultural factors that contributed to the RBMK becoming the standard design. More, it was the RBMK’s capacity to embody a vision of the future of the Soviet Union that led to this decision. A few years later, this vision fell apart when the RBMK design suffered from the worst reactor accident the nuclear industry ever had—only to find itself in the middle of a war zone some 36 years later.

Over the past decade, we have witnessed similar hype for small reactors proposed as a potential game-changer for the future of nuclear power. Small modular reactors, or SMRs, are much smaller than the current standard 1000- to 1600-megawatt electric output reactors. Mini-reactors have been heralded as nuclear champions by their promoters, able to meet safety and regulatory requirements, tackle security and nonproliferation concerns, and even embody sociotechnical visions of what a world of abundance powered by SMRs might look like. Such visions have included cheap, risk-free energy that eliminates reactor accidents, an end to energy scarcity, with SMRs powering remote communities and developing economies, a plentiful world where water needs are fulfilled by SMR-powered desalination stations, and an environmentally friendly energy source embedded in a virtuous fuel cycle, with SMRs producing carbon-free and waste-free electricity. Small reactors even have their place in visions of space exploration, assisting future societies in the colonization of the moon, Mars, and possibly other extra-terrestrial worlds.

Scientists have started working on independent reviews of those claims. The results showed that SMRs do not necessarily perform better than gigawatt-scale reactors on a variety of measures. A recent Stanford-led study published in the Proceedings of the National Academy of Sciences (PNAS) provides for the first time a comprehensive analysis of the nuclear waste generated by small modular reactors. The study concludes that most current SMR designs will actually significantly increase the volume and complexity of nuclear waste requiring management and disposal when compared to existing gigawatt-scale light water reactors.

Here, Bulletin associate editor François Diaz-Maurin talks with Lindsay Krall, the lead author of that study and a former MacArthur postdoctoral fellow at Stanford’s Center for International Security and Cooperation (CISAC) who is now based in Sweden.

 

Lindsay Krall

François Diaz-Maurin: Before we start, most of our readers won’t know what a small reactor is, to begin with. So, let’s help them here. What are small modular reactors, and how do they differ from conventional large-scale reactors?

Lindsay Krall: Sure. A small modular reactor is defined as a reactor with less than 300-megawatt electric output. So “small modular” just refers to the size and the construction strategy, the latter being that the reactors are fabricated as modules in a factory and then shipped on-site by truck where they are assembled. That’s what modular means. Small refers to the energy or the electric output. Sometimes developers call these reactors “plug-and-play.” SMRs can include a huge variety of reactor types depending on the coolant and moderator that they use—from light water to molten salt, sodium, graphite, gas-cooled graphite-moderated reactors, to even lead-cooled reactors.

Diaz-Maurin: In your study, you say that almost half of the SMR designs listed by the IAEA are considered “advanced” reactors that can employ “chemically exotic” fuels and coolants…

Krall: Exactly. Another way in which SMRs differ from current reactors is that, in some of the designs, reactors are passively cooled. That is, instead of having pumps that circulate the coolant, these reactors rely on internal, natural convection around the reactor core. Because they are passively cooled, developers consider these reactors to be “inherently safe.” So, if there is a loss of electricity on-site, the reactor will continue to stay cool through this natural convection flow, because they are not relying on external electricity to run a pump.

Diaz-Maurin: Great. Let’s turn to your research findings now. Most SMRs are said to adopt an “integral” design, in which the reactor core and auxiliary systems are all contained within a reactor vessel. Now, because of their smaller size and compact design, one can expect that SMRs will generate less waste than larger reactors that operate at the gigawatt scale. But you have reached the opposite conclusion in your study, that SMRs will produce more voluminous and chemically/physically reactive waste than light-water reactors. And this by factors of 2 to 30. How is that? It seems counterintuitive…

Krall: Well, one thing that’s clear from the analysis is that the waste output really differs depending on the type of coolant the reactor is using. If it’s using water, then we have processes to treat that water and decontaminate it and hold it so the water coolant itself does not become radioactive waste. However, for a sodium-cooled reactor, for instance, that sodium coolant is likely to become low-level waste at the end of the reactor’s lifetime, because it becomes contaminated and activated during reactor operation. So, the “up to 30 times more waste” that’s been driving the headlines, it’s mostly the sodium coolant. Another aspect is that things in a small reactor do not scale intuitively compared to other forms of energy. For instance, one thing I went into was “neutron leakage.”

Diaz-Maurin: Let’s stay here for a moment. In the paper, you attribute the higher volume of waste generated mainly to “an intrinsically higher neutron leakage associated with SMRs.” Can you explain what neutron leakage means and how it’s driving your results?

Krall: Sure. To put it simply, neutrons are released when there’s a fission reaction. Then, those neutrons are supposed to go forth to propagate the fission chain reaction and help the reactor sustain criticality. But in a small reactor, due to that smaller core size, you’re having more of these neutrons that leak out of the periphery of the fuel. It’s essentially due to the fuel’s surface area to volume ratio, but not exactly. Still, one big issue is that this neutron leakage is then leading to lower fuel burnups. [Fuel burnup – or fuel utilization – is a measure of how much energy is extracted from a given nuclear fuel. The higher the burnup, the more efficient the reactor is.] So that’s what I mean by more physically reactive waste. Say, you start at the same enrichment level, as in a large reactor, the small reactor will have a lower fuel burnup. And due to that lower fuel burnup, you’ll end up with a higher concentration of fissile material in the spent fuel, which can increase the likelihood of recriticality in the spent fuel. [Recriticality is a measure of the potential for fissile materials to spontaneously start a sustained fission reaction.] If a storage or disposal canister fails and becomes flooded with water, recriticality is a bigger risk with the spent fuel from a small reactor and that needs to be mitigated. An effective way to mitigate that risk is to avoid putting a critical mass inside a spent fuel canister.

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Diaz-Maurin: Now let’s go back to the wastes themselves. What type of waste are we talking about, anyway? In the paper, you mention spent fuel, high-level waste, and long-lived and short-lived decommissioning waste… Can you walk us through the waste streams from SMRs and how they differ from large reactors?

Krall: Yeah, so SMRs, just like standard commercial reactors, produce spent fuel. And that spent fuel has a particular burnup based on its initial enrichment and how the reactor operated. So, it’s not, you know, like these claims, “oh, we’re going to reduce the mass of spent fuel by 90 percent.” It turns out that a lot of those claims assume that there are several rounds of reprocessing. But based on the license applications of the vendors to the [US Nuclear Regulatory Commission] for these reactors, they’re not. The reprocessing isn’t factored into the reactor design. So, I just use the burnups that are being stated in these reactor applications—when they are stated, because oftentimes, they’re redacted. So just like a large reactor, small modular reactors produce spent fuel. And that spent fuel has a lot of different characteristics that need to be taken into account when you’re storing, transporting, and disposing of it.

Diaz-Maurin: In the paper, you say that compared to large reactors, SMRs will increase the volume and complexity of those wastes. I get the volume part. But what is this complexity about?

Krall: It’s what I mean with “different characteristics” of the spent fuel, not least being this fissile isotope concentration. It also produces heat. It has a particular radionuclide composition, including fission products, which can be both short- and long-lived. And so, I employed four different metrics to measure the spent fuel. And then the long-lived low- and intermediate-level waste in the article is the activated waste. This waste is so close to the reactor core that it absorbs the neutrons that are being leaked and becomes activated. In current reactors, the activated waste is mostly steel from the structural components that keep the core intact. This steel will also become activated in SMRs and, as a result, it will contain short- and long-lived nuclides that need to be dealt with during decommissioning. Reactor decommissioning will require radiation shielding and that steel, the activated steel, will also need to be disposed of in a geologic repository.

Diaz-Maurin: What’s the difference between short-lived and long-lived waste from the perspective of waste management?

Krall: Long-lived waste should be disposed of in a permanent geologic repository—a passively safe, rock cavern with multiple engineered barriers—where the radioactive materials discharged from the reactors will be contained over long periods of time so that they can decay. Short-lived waste includes mostly the reactor structures that have come in contact with a primary coolant that was circulating around the reactor core and through the steam generators. This waste also should go to some sort of disposal site. Sweden, for instance, has a 50-meter-deep repository, whereas some countries just dispose of it in shallow landfills.

Diaz-Maurin: I think I get the complexity too now. And, so, because of that complexity, I see why you need to use several metrics like the chemistry of the spent fuel matrix, its radionuclide content, the heat generated, the radioactive decay, etc. Yet, in the paper, you mention that nuclear technology developers and advocates often employ simple metrics, such as mass, volume, and radioactivity. Indeed, most critics of your study that I’ve seen tend to focus on the waste volume part. Do you think nuclear engineers don’t understand how the chemistry and physics of the spent fuel will affect waste management and disposal?

Krall: I think nuclear waste management is a pretty niche field. It’s a small community of people that think about very bizarre things on a day-to-day basis, like, the 100,000-year evolution of the hydrology at this random location in Sweden. So, I think, there’s definitely a disconnect between the people working on the back end of the fuel cycle—especially with geologic repository development—and those actually designing reactors. And, you know, there is not a lot of motivation for these reactor designers to think about the geologic disposal aspects because the NRC’s new reactor design certification application does not have a chapter on geologic disposal. So…

Diaz-Maurin: That’s interesting, because some developers of SMRs claim they already include a waste disposal program as part of their design program. That would be indeed a much-welcomed development, compared to how conventional reactors have been deployed…

Krall: Well, yes, if they had a chapter on geologic disposal, that would be helpful because at least their proposals could be reviewed in some way or another. I’ve heard reactor designers propose a number of left-field ideas, for instance, “we’re going to dump this sodium reactor in a deep borehole.” People can just shout random thoughts because there’s no accountability for them in proposing an unworkable idea. But if they wrote these proposals down on paper in an NRC application, then at least there might be some way to regulate these unconventional waste management ideas.

Diaz-Maurin: Let’s assume for a moment that license applications of SMRs do include a chapter on waste disposal aspects. Still, things would not be that straightforward. There would still be the problem of the public acceptance of geologic repositories as a possible limiting factor.

Krall: Yes, the public acceptance… I don’t know if that’s anything a reactor designer is going to achieve with geologic repository development. As I said, these nuclear waste management companies are a very niche community. And there are good reasons for that. The most successful geologic disposal programs are those that have best managed to decouple themselves from reactor construction. So, waste management organizations have intentionally separated themselves from the larger nuclear industry as part of their strategy to work towards public acceptance. It would not be beneficial for these organizations to promote reactors and get dragged into the pro- vs. anti-nuclear politics. The best way we can approach it is as: The waste is here, and it needs to be disposed of in a long-term safe way. I don’t think that somebody who is promoting these reactors will achieve public support for a geologic repository.

Diaz-Maurin: Since it was published on May 30, your study generated a lot of responses, including harsh ones, from the nuclear technology developers and advocates. I guess you knew the conclusions of your article would cause some controversy in the nuclear community. But were you surprised at the level of those reactions?

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Krall: Yes, there have been a lot of responses—both positive and negative—and I’ve been surprised at everyone’s reaction. You know, for me, coming from the science area where nobody reads the stuff I write—I mean, I can’t even get my supervisors to read it. [Laughter] And then to go to something that’s making headlines… this was a bit shocking for me. And then to see that those headlines focused so heavily on the volume estimates. You know, like, “Small nuclear power projects may have big waste problems”, “Mini nuclear reactors have an outsized waste problem”, and all of that… Obviously, it’s an exciting headline. But that’s not exactly the point I was trying to make in the article. Another issue, I guess, is that I didn’t really know how the article would be released. There was a copy of the paper circulated to the media or to the press some five days in advance of the article’s publication. So, reactor developers were contacted by the press about the article before it was even published. As a scientist, I was just thinking, “Oh, thank God, this paper got accepted, and I don’t have to work with it anymore.” But then the release of the paper shocked me.

Diaz-Maurin: Some critics say you used outdated information in your study. For instance, NuScale’s chief technology officer, Jose Reyes, wrote a letter to the PNAS editor-in-chief where he says your analysis focused on the NuScale 160 megawatt thermal (MWt) core, but that they had already implemented another reactor design, the NuScale 250-MWt core. Reyes then adds that this new design does not produce more spent fuel than existing light water reactors. Does this contradict your findings?

Krall: It doesn’t. It’s actually exactly in line with my findings. We used the certified NuScale reactor, the 160MWt because, with their application to the NRC, there was enough technical data to perform our analysis. It’s interesting to note that their larger 250MWt reactor is going to have to undergo a whole new licensing process. They’re submitting that license application, I think, in December. So, it’s a bit surprising that they’re now marketing a reactor that isn’t licensed. It does seem that this larger reactor will have a higher burnup, of 45 megawatt-days per kilogram, according to NuScale. Well, first of all, that’s still lower than existing full-scale reactors. So, they’re still going to produce more waste, which is a far cry from the general belief that all SMRs will produce less waste. It would be good if they had a higher burnup. But, the higher burnup and consequently lower waste volume, I will guess, is partly driven by the fact that the new design is a larger reactor. So, just as our paper argues, smaller reactors generate more waste.

Diaz-Maurin: So does it mean we should expect future designs of “small” reactors to be up to, say, 999-megawatt electric output?

Krall: Yeah, I think on the larger side of the SMR spectrum, the waste will be more similar to those of existing reactors. So, an important point of the paper is that you need to choose an SMR design carefully, with insight from the back end, so as to avoid disrupting the spent fuel management system too much. In countries with active waste management programs, it’ll be easier to get insight from the back end. But in countries that don’t have such programs, how are people purchasing these reactors going to get insight from the back end? That is not clear to me, especially when it’s not part of the NRC license application.

Diaz-Maurin: In his letter, Reyes also says that you did not contact NuScale for information or clarifications regarding data, such as fuel burnup, that he says they had made publicly available. Is this true?

Krall: We are being accused of not discussing the study with reactor designers. This isn’t true. We did seek information from them, I mean, usable information about their actual design being submitted to the NRC. That information was not given to us. Instead, designers would only speak in generalized terms about an ideal SMR fuel cycle, which is not necessarily what is actually being licensed. And, even this generalized information would be marked as proprietary, not something that I could publish. As scientists, we prefer to reference peer-reviewed analyses. But there is a scarcity of peer-reviewed information in this field.

Diaz-Maurin: The development of SMRs has been around since about the early 2000s. Why are there still only a few studies that analyze the management and disposal of nuclear waste streams from SMRs?

Krall: Well, first, there’s not a lot of funding for it. In my case, for instance, I did most of the research during these fellowship positions where I had funding for it. But I ended the fellowships before the paper was published. So, I spent some time editing the manuscript, submitting it, and revising it all on my own time. And there aren’t a lot of motivating forces to get funding for independent analyses of the waste streams. Since the dominant narrative is that “the waste is manageable and similar to what we currently deal with,” it results in a lack of funding for independent technical reviews of the nuclear fuel cycle. And it’s a real problem.

Diaz-Maurin: As you know, at the Bulletin of the Atomic Scientists, we are committed to reducing manmade threats to our existence. And we are also dedicated to one clear goal of advancing a safe and livable planet. Do you think SMRs could help make our planet a safer place, as their developers tend to suggest?

Krall: I think it depends on the SMR design. For certain SMRs, especially the larger ones, I don’t know where the sweet spot is, but I think they can be viable as long as you choose to construct the right design. But how are you going to choose the right design without any insight from the back end? I think SMRs can be viable if you have insight from the back end when you’re both designing and selecting a design.

Diaz-Maurin: Let me play a little devil’s advocate here. Nuclear waste disposal is becoming reality. Finland just authorized the construction of its deep geological repository for spent nuclear fuel. And other countries are following closely, like France and Sweden, where you work. So why would a little more waste from small modular reactors necessarily be a problem?

Krall: In a country that has a spent fuel management program, whatever design they’re choosing to construct, developers will have insight from the back end, both for decommissioning and for geologic disposal. So I think, SMRs can be deployed safely, as long as the back end is being managed responsibly. But in countries where that’s not the case, I think it’s a bit more like the Wild West.

François Diaz-Maurin is the associate editor for nuclear affairs at the Bulletin of the Atomic Scientists. Previously, Diaz-Maurin was a... Read More

Molten salt reactors were trouble in the 1960s—and they remain trouble today

By M. V. Ramana | June 20, 2022
Bulletin of the Atomic Scientists
 

A technician prepares salts for use in MSRE in 1964. By Oak Ridge National Laboratory. Accessed via Flickr. CC BY 2.0.


Molten salt nuclear reactors are all the rage among some nuclear power enthusiasts. They promise designs that will soon lower emissions from shipping, be cheaper to run and consume nuclear waste, and be transportable in shipping containers. The Canadian government has provided two companies, Terrestrial Energy and Moltex, with tens of millions of dollars in funding. Indonesia’s Ministry of Defense has sponsored a study of thorium-based molten salt reactors. The International Atomic Energy Agency organized a webinar calling molten salt reactors “A game changer in the nuclear industry.” Unsurprisingly, China has plans to build one.

 

MSRE Molten Salt Reactor Oak Ridge National Lab. Oak Ridge Tennessee 2003. DOE photo by Lynn Freeny. US government photo accessed via Flickr.

Unlike other nuclear reactor designs that can claim multiple roots, the technology underlying molten salt reactors has a fairly clear origin: the Oak Ridge National Laboratory in Tennessee. All molten salt reactors are based, in one way or another, on the Molten Salt Reactor Experiment that operated at Oak Ridge from 1965 to 1969. That experimental reactor, in turn, was based on another experimental reactor, the Aircraft Reactor Experiment, that had operated a decade earlier at the same facility.

Among developers, the Molten Salt Reactor Experiment has a legendary status. For example, in 2015, an official from Terrapower, the nuclear venture funded in part by Bill Gates, noted that his company was “excited to celebrate and build upon” the experiment by designing a molten chloride fast reactor. His accompanying slide show reinforced the message with pictures of the Molten Salt Reactor Experiment assembly, the red hot heat exchanger, and Alvin Weinberg, the leader of Oak Ridge at that time, noting that the experiment had operated for 6,000 hours. Also in 2015, Terrestrial Energy’s David LeBlanc made “a kind of pilgrimage to Oak Ridge” to celebrate the 50th anniversary of the Molten Salt Reactor Experiment becoming critical.

Many molten salt reactor developers and proponents seem to have decided that the Molten Salt Reactor Experiment experience was so successful that all that remains is for it to be scaled up and deployed across the world. But is this really the case? A careful look suggests otherwise.

Molten salt reactors’ early history. Molten salt reactors go back to the US Air Force’s failed effort to build a nuclear-powered, long-range bomber aircraft. The Air Force spent more than $1 billion (over $7 billion in today’s dollars) between 1946 and 1961 on its Aircraft Nuclear Propulsion program. President John F. Kennedy, seeing how little had been achieved, told Congress on March 28, 1961 that the possibility of success in the foreseeable future was “still very remote” and recommended terminating the program.

As part of this effort, the Air Force made Oak Ridge National Laboratory responsible for building the Aircraft Reactor Experiment as part of its effort to fly a bomber on nuclear power. The 2.5 megawatt reactor operated for a mere nine days in November 1954. Some Oak Ridge officials considered running the reactor longer, but others grew concerned about overheating of one of the reactor components. That concern was legitimate; five days later, this component failed and “released radioactive gas into the reactor compartment.” But Oak Ridge National Lab officials were undeterred. For them, the experience showed “the feasibility of molten-salt fuel” and they “persuaded the Atomic Energy Commission to fund a study of molten-salt power reactors.” In 1958, the commission did just that, and thus began the Molten Salt Reactor Experiment.

To understand the interest in molten salt reactors, start by adopting a 1950s mindset. At the time, nuclear power was expected to expand rapidly, and some energy planners were worried that there would be insufficient uranium to fuel all the reactors to be built over upcoming decades. Alvin Weinberg, the head of Oak Ridge, expressed this eloquently when he prophesized that humanity would need to “burn the rocks” in what are called breeder reactors in order to live a “passably abundant life.” While the dominant types of reactors around the world (light water reactors and heavy water reactors) use only a small fraction of the uranium and thorium found in the Earth’s crust, breeder reactors can exploit a much larger fraction of these minerals.

The concern among nuclear power advocates about running out of uranium was also at the heart of another major nuclear development during this period: the liquid metal (sodium) cooled fast breeder reactor. These reactors were an effort to tap the energy present in the uranium-238 isotope that is not used in standard light and heavy water reactors by converting it into plutonium. Glenn Seaborg, who discovered the element and rose to become Chairman of the US Atomic Energy Commission from 1961 to 1971, predicted in 1970 that, by the year 2000, plutonium “can be expected to be a predominant energy source in our lives.” By contrast, the molten salt reactors were mostly intended as a pathway to use thorium, which was more plentiful than uranium, by converting it into uranium-233.

In retrospect, these expectations proved mistaken in three ways. First, energy demand has risen much more slowly, both in the United States and globally, than predicted. For example, in 1959, Weinberg assumed that the global population would stabilize at 7 billion and that it would need at least 1.9 billion, billion BTU per year. In comparison, in 2020, the world used a little over a quarter of this level of energy for nearly 8 billion people.

Second, nuclear energy proved much more expensive than envisioned in the heady “too cheap to meter” era. As nuclear power’s poor economics became apparent, reactor construction declined dramatically and has never achieved anywhere near the levels seen in the 1970s and 1980s. (Accidents at Three Mile Island and Chernobyl only reinforced this trend.) The United States illustrates the drastic difference between expectation and reality. The Atomic Energy Commission projected that US nuclear power generating capacity in 2000 would be 1.1 million megawatts (or 1,100 gigawatts). In fact, US nuclear capacity only reached a maximum of 101 gigawatts, and it has since declined to less than 95 gigawatts as of June 2022 (after the Palisades reactor was shut down). Globally, nuclear energy’s share of electricity generation has sunk from a maximum of 17.5 percent in 1996 to just over 10 percent in 2020.

Third, uranium proved to be more ubiquitous than anticipated, and global uranium resource estimates have continuously increased. The International Atomic Energy Agency and the Organization for Economic Co-operation and Development’s Nuclear Energy Agency calculate that the world’s resources of cheaply available uranium ore are adequate to fuel the global reactor fleet, even in the event of an increase in nuclear power generation.

All of these realizations were, of course, only to be had in the future. In the 1950s, when the molten salt reactor programs were actively pursued, there was an air of urgency. This urgency was reflected in the break-neck speed with which the Molten Salt Reactor Experiment, Oak Ridge’s proposal for the next step in the molten salt reactor research process, was designed and constructed. As one of the Oak Ridge team leaders described it, “Design of the [Molten Salt Reactor Experiment] started in the summer of 1960, and construction started 18 months later, at the beginning of 1962. The reactor went critical in June 1965.”

In 1965, when the reactor started operating, it was fueled by a mixture of 150 kilograms of depleted uranium and 90 kilograms of weapons-grade, highly-enriched uranium (93 percent of uranium-235). After March 1968, the fuel was changed to one involving another weapons-usable material, uranium-233, which was derived from thorium. After this switch, the Molten Salt Reactor Experiment went critical in October 1968 and reached full power in January 1969. But at the end of that year, the experiment shut down. No more molten salt reactors have been built since.

The Molten Salt Reactor Experiment operation. Proponents of molten salt reactors have claimed for decades that the Molten Salt Reactor Experiment operated successfully. Indeed, they started making this claim even when it had barely started operating. In May 1966, for example, Paul Haubenreich, Oak Ridge National Laboratory associate director, cockily announced that the experiment “will live up to the name which we think goes with the initials M.S.R.E.—Mighty Smooth Running Experiment.” This, after listing many problems, including a basic one that was never resolved.

 

Molten Salt Reactor Experiment remote handling cell.

 By Oak Ridge National Laboratory. Accessed via Flickr. CC BY 2.0.

That basic problem was the reactor’s power level. The Molten Salt Reactor Experiment was designed to produce 10 megawatts (MW) of heat. The power level is given only in terms of heat production because its designers did not even try to generate electricity from the power produced in the reactor. Instead, the experiment just dissipated the heat produced to the surrounding air.

But this design power level was never reached. As Haubenreich described while pronouncing that the experiment was running “mighty smooth,” the operators “ran into some difficulties” and could only operate “at powers up to 5 MW.” Nevertheless, he expressed the confident expectation that the reactor would “be at 10 MW within a couple of weeks.” In fact, Haubenreich later admitted in a paper written after the reactor was shut down, the highest power level it reached was only 8 MW. (One Oak Ridge publication even says 7.4 MW.) It turned out that the designers of the reactor had “miscalculated the heat transfer characteristics” of the system used for dissipating the heat produced into the atmosphere, and the reactor could not operate at its intended power level.

Even for this lower power output, operations were anything but smooth. At the most general level, the fact that the reactor operated for just 13,172 hours over those four years, or only around 40 percent of the time. In comparison, the average commercial nuclear power plant in the United States operates at upwards of 90 percent of the time. The longest periods of sustained high power operations in the Molten Salt Reactor Experiment were between February to May in 1967 and late January to May in 1969.

During its operational lifetime, the Molten Salt Reactor Experiment was shut down 225 times. Of these 225 interruptions, only 58 were planned. The remaining interruptions were due to various technical problems, including: “chronic plugging” of the pipes that led into charcoal beds intended to capture and remove radioactive materials so the reactor could operate; failures of the blowers that removed the heat produced in the reactor; and fuel draining through the so-called freeze valve safety system intended to prevent an accident.

These frequent failures led to a large gap between the proposed operating schedule and the actual operations of the Molten Salt Reactor Experiment. For example, the proposed schedule called for the experiment to run at full power (i.e. 8 MW) from May to early August in 1968. But the reactor was down from April to July of that year.

One persistent problem was with the electrical system, which experienced “eleven important failures.” Of these, five were “caused by electrical storms, one by a cable failure at a component-cooling pump, one by an overload of the main process-power breaker, one by an arc between a 13.8-kV line and an activator rod to the line fuse, one by a failure of the main transformer primary fuse, one by a failure of the auxiliary transformer primary fuse, and one by a failure of the drain-tank space cooler motor. These interruptions varied in length from a few minutes to several days.” Such unexpected failures and shutdowns ended only in December 1969, when the Molten Salt Reactor Experiment was shut down.

The patchy experience of the experiment was by no means unique. Many other reactor designs have been plagued by unreliable operations and frequent shutdowns, that in many cases only became worse when scaled up. Consider, for example, sodium cooled fast breeder reactors. France, the country most reliant on nuclear power, tried to commercialize this technology after operating pilot-scale and demonstration reactors. This “commercial” version was the Superphénix, which started operating in 1986, experienced a series of accidents, and was shut down in 1997. During this period, it generated less than 8 percent of the electrical energy of what it would have generated running at full power round-the-clock. In the United States, the first and only commercial sodium cooled breeder reactor, Fermi-1, suffered a disastrous meltdown in 1966 as a result of a series of failures that had been dismissed as not credible by reactor engineers. Likewise, high-temperature, gas-cooled reactors have historically performed poorly.

The Molten Salt Reactor Experiment aftermath. For Oak Ridge officials and other molten salt reactor proponents, these problems with the Molten Salt Reactor Experiment were not worthy of significant concern. They moved forward with plans to build a larger molten salt breeder reactor. (Remember that the ultimate goal was to use thorium to breed nuclear fuel.) But the experiment did identify major hurdles in the path of building reliable molten salt reactors.

Here’s a key concern: Materials used to manufacture molten-salt-reactor components must maintain their integrity in highly radioactive and corrosive environments at elevated temperatures. The corrosion is a result of the reactor’s nature, which involves the use of a fuel consisting of uranium mixed with the hot salts for which the reactor is named. As anyone living near a seashore knows, chemically corrosive salt water eats most metallic objects.

To deal with this problem, Oak Ridge developed a new alloy known as IN0R-8 or Hastelloy-N in the late 1950s. While Hastelloy-N did not get significantly corroded—at least during the four years of intermittent operations—it had two significant problems. First, the material had trouble managing stresses. It became brittle, for example. Second the material developed cracks on surfaces exposed to the fuel salt. Both of these could lead to the component failing.

These problems remain relevant. Even today, no material can perform satisfactorily in the high-radiation, high-temperature, and corrosive environment inside a molten salt reactor. In 2018, scientists at the Idaho National Laboratory conducted an extensive review of different materials and, in the end, could only recommend that “a systematic development program be initiated.” In other words, fifty years after the molten salt reactor was shut down, technical experts still have questions about materials development for a new molten salt reactor design.

A few years after the Molten Salt Reactor Experiment was shut down, the Atomic Energy Commission terminated the entire molten salt reactor program, although it continued to fund the molten salt breeder reactor program until the end of fiscal year 1976.

Molten salt reactor proponents view the termination of funding as a result of either institutional politics or historical factors. They point to Milton Shaw—the head of the Atomic Energy Commission’s Division of Reactor Development and Technology—and his strong preference for the liquid metal fast breeder reactor. As Oak Ridge National Laboratory program director Herbert MacPherson put it, the “fast breeder program… got an early start and had copious government development funds being spent in many parts of the United States. When the [molten salt reactor] development program had progressed far enough to justify a greatly expanded program leading to commercial development, the [Atomic Energy Comission] could not justify the diversion of substantial funds” from these efforts. MacPherson suggested that the institutional problem was that the “political and technical support” for molten salt reactors was “too thin geographically.”

Director Alvin Weinberg’s explanation revolved around the historical domination of nuclear power by physicists. In a letter to Glenn Seaborg, he wrote, “our problem is not that our idea is a poor one—rather it is different from the main line, and has too chemical a flavor to be fully appreciated by non-chemists.”

But these explanations disregard the technological problems of molten salt reactors. Indeed, anyone who looked at the spotty operating record of the Oak Ridge reactor ought to have been skeptical about this technology. The subsequent failure of the seemingly more promising fast breeder reactor technology should prompt greater skepticism, not less.

The Atomic Energy Commission, for its part, justified its decision in a devastating report that listed a number of problems with the large molten salt reactor that Oak Ridge scientists had conceptualized. The list included problems with materials, some of which have been earlier described; the challenge of controlling the radioactive tritium gas that is produced in molten salt reactors; the many large components, such as steam generators, that woud have to be developed from scratch (as researchers had no experience with such components for a molten salt reactor); the difficulties associated with molten-salt-reactor maintenance because radioactive fission products would be dispersed throughout the reactor; some safety disadvantages (though these are balanced by pointing out some of the safety advantages); and problems with graphite, which is used in molten-salt-reactor designs to slow down neutrons, because it swells when subjected to the nuclear reactor’s high radiation doses.

Other institutions too questioned the idea. A 1975 Office of Technology Assessment report listed the pros and cons of maintaining support for the molten salt breeder reactor program. An important set of arguments listed there proved prescient: “the [molten salt breeder reactor] may never work, its economics would be doubtful even if it did, and the chances of needing it are small.” As a result, in the years after the Molten Salt Reactor Experiment was shut down, many arguments were advanced to abandon the molten salt route, including not throwing good money after bad.

The Molten Salt Reactor Experiment’s long difficult tail. When one looks for publications with the title “molten salt reactor experiment” on the University of British Columbia library page, only nine results, all published before 1975, pertain to the actual operations of the reactor. The remaining 41, including a 1984 report titled “Preliminary decommissioning study reports: Volume 5, Molten Salt Reactor Experiment,” all deal with managing the reactor components or the radioactive materials involved in the experiment. The distribution of the numbers of papers indicates the challenge of dealing with the waste resulting from a small molten salt reactor.

Dealing with radioactive salt wastes involves at least two separate concerns. The first, ongoing problem is that managing the radioactive salts that contain the uranium isotopes and the fission products is difficult. In the 1990s, researchers discovered that uranium had migrated and settled in other parts of the facility, leading to the possibility of an accidental criticality.

The second challenge is that of securely storing the uranium-233 from the Molten Salt Reactor Experiment. Although the uranium-233 used in the Molten Salt Reactor Experiment is but a small part of the larger US stockpile of the substance, it occurs in chemical forms that are difficult to manage. Further, urarnium-233 is usable in nuclear weapons, and any loss of this material might lead to security concerns.

In all, the costs incurred so far have run into the hundreds of millions of dollars—dozens of times the cost of constructing the reactor itself. Oak Ridge continues to spend around ten million dollars (roughly the cost of the reactor) every year, just to manage these wastes on site. In addition to the problems mentioned above, there are miscellaneous challenges requiring expensive engineering. For example, Oak Ridge began a $4.7 million project in 2019 to upgrade electrical and fire suppression systems.

Assuming that these challenges can all be managed, Oak Ridge and the Department of Energy will also need to address the ultimate challenge of trying to dispose of these wastes in some kind of a geological repository. Uranium in molten salt reactors is in chemical forms that are “not known to occur in nature” and waste disposal experts are unclear “which, if any, disposal environment could accommodate this high-level waste.”

Molten salt reactors are a bad idea. The Molten Salt Reactor Experiment’s history is riddled with extensive problems, both during its operational lifetime and the half century thereafter. These problems were not accidental but a result of the many material challenges faced by the reactor itself.

Any other molten salt reactor will encounter these problems too. France’s Institut de Radioprotection et de Sûreté Nucléaire, the Nuclear Innovation and Research Office in the United Kingdom, and other research laboratories have all drawn this conclusion. According to the Institut de Radioprotection et de Sûreté Nucléaire, “numerous technological challenges remain to be overcome before the construction of an MSR can be considered.”

Should molten salt reactors ever be constructed, they are unlikely to operate reliably. And if they are deployed, they would likely result in various safety and security risks. And they would produce several different waste streams, all of which would require extensive processing and would face disposal related challenges. Investing in molten salt reactors is not worth the cost or the effort.

This article has benefited from research support from Maggie Chong, a materials engineering student at the University of British Columbia.

The California Church Shooting Shows the Long Arc of Taiwanese History

The island’s divisive political history is tied to the shooter’s apparent motive.


DAN SPINELLI

Reporter Bio
 Mother Jones

After a gunman attacked a Taiwanese Presbyterian church in Laguna Woods, 

California, misinformation spread about the shooter's ethnic background.

Ashley Landis/AP

After a gunman fired on six people at a Taiwanese Presbyterian church in Laguna Woods, California, last Sunday, killing one and injuring five, the news of a likely hate crime ricocheted across Chinese-language group chats and the Taiwanese press. Hate crimes against Asian Americans have sharply increased since the start of the pandemic, according to the Center for the Study of Hate & Extremism at California State University, San Bernardino, and it seemed possible that this was another example of that phenomenon.

But the shooting quickly grew complicated in other ways relating to the ethnicity of the shooter and a possible motive that relates to political tensions between mainland China and the island of Taiwan.

In the initial aftermath, Orange County Sheriff Don Barnes identified the suspect, 68-year-old David Chou, as a native of mainland China who “specifically targeted the Taiwanese community.” Many of the members of Geneva Presbyterian Church in Laguna Woods are “elderly Taiwanese immigrants,” the Los Angeles Times reported. That bit of news gained traction in outlets like the Associated Press, which described Chou as a “Chinese immigrant motivated by hate for Taiwanese,” an angle that was further amplified in Apple Daily Taiwan, an online media outlet. At a time of increasing tensions between China and the United States, who have often clashed over US support for Taiwan, the shooting appeared to be a local microcosm of Chinese aggression toward Taiwan.

But those early reports turned out to be incorrect. Chou, the Taiwanese press later found, was born on the island to Chinese parents who had fled the mainland after the Chinese Communist Party took power in 1949. His writings and people who knew him suggest that Chou strongly supports the reunification of Taiwan and China and was hostile to the predominant view among many Taiwanese that the island should retain a cultural and political identity that is distinct from the mainland. (Though the Chinese government still treats Taiwan as a breakaway province, the self-governing island has been de facto independent since 1949.)

In April 2019, Chou was photographed in Las Vegas attending an event organized by a group that supports the reunification of Taiwan and mainland China. While at the event, he is seen in front of a banner praising the populist Taiwanese politician Han Kuo-yu. “I spoke to Chou twice, but I found his thoughts too radical and kept a distance afterwards,” Jenny Koo, the organization’s chair, told Vice. “Since the latter half of 2019, he did not participate in any of our activities and was no longer a member.”

NBC News spoke with members of the Taiwanese Association of Las Vegas, where Chou had attended several meetings, and reported that he frequently challenged the prevailing, pro-independence tenor of the group. “Chou grabbed the microphone at a 2020 seminar and, at one point, proclaimed, ‘We are all Chinese,'” the wife of one of Chou’s acquaintances told NBC News.

Before heading to Laguna Woods, Chou sent his writings, titled “Journal of the Independence-eliminating Angel,” to World Journal, a popular Chinese-language newspaper in the United States that generally supports closer ties between Taiwan and China. It is not yet clear why he attacked members of that particular church—and various Taiwan experts with whom I spoke had heard different motives, including some nonpolitical ones—but the Presbyterian Church in Taiwan has for decades supported Taiwanese self-determination, which runs contrary to Chou’s rabidly pro-unification views.

Whatever his motivation, Chou “was affiliating himself with certain organizations that have a very particular toxic, nationalist stance on cross-strait relations, especially on the pro-independence movement in Taiwan,” Jessica Drun, nonresident fellow in the Atlantic Council’s Global China Hub, told me. Taiwanese political leaders have issued some restrained comments on the shooting, but have not drawn attention to Chou’s views.

Chou’s politics and the early reports that he was a mainlander led to some conspiracy theories that he was acting on behalf of China’s United Front, a Communist Party influence operation aimed at countering overseas enemies to the Chinese regime. But to Brian Hioe, a Taiwanese-American journalist who has followed the media coverage of the Laguna Woods shooting, that kind of violent action seems unlikely. “It proves hard to imagine that China’s United Front would think that the cause of unification could be advanced by gunning down a defenseless church delegation,” Hioe wrote. “In fact, Chou’s actions actually seem more characteristic of American gun culture, and America’s culture of mass shootings.”

There does not appear to be some grand conspiracy at work. Chou’s attack, much like the deadly shooting in Buffalo, is something more frighteningly routine: a set of poisonous ideas fueling an act of hate.

This piece has been updated to more clearly characterize Chou’s apparent political motive.

‘Desperately’: Trump ‘wanted to walk into the House with an armed mob’ says Yale historian

David Badash, 

The New Civil Rights Movement
June 29, 2022



The revelations from former Trump White House aide Cassidy Hutchinson are being called "bombshells" and, according to a former advisor to the U.S. House Select Committee on the January 6 Attack, a "cluster bomb."

But one Professor of History and American Studies at Yale University, Dr. Joanne Freeman, is urging Americans to focus on an important part of Hutchinson's testimony.

"People are focusing on the drama of [Donald Trump] trying to grab the steering wheel to force his car to go to the Capitol," Dr. Freeman writes. "But far more revealing -- and alarming -- is the fact that he wanted to walk into the House with an armed mob."

"Again: think COUP."

Freeman, the author of "The Field of Blood: Violence in Congress and the Road to Civil War," adds: "Hutchinson testified that there was discussion about having him enter the House chamber."

Hutchinson also testified that Trump and Meadows knew the rally-goers and insurrectionists were armed, some heavily. And he demanded the "mags," the magnetometers, or "metal detectors," be removed.

“I don’t fucking care that they have weapons, they’re not here to hurt me.," Trump allegedly said, according to Hutchinson. "They’re not here to hurt me. Take the fucking mags away. Let my people in. They can march to the Capitol from here, let the people in and take the mags away.”

"Today we saw 1/6 was a plot to overturn the election w/*deliberately incorporated* violence," she says.

"That was wild," Freeman said after the hearing ended.

Hutchinson did in fact testify there were discussions about Trump walking into the House chamber, which would be yet another violation of centuries of precedent: the President cannot just show up; he must be invited.

Company fired workers who refused to take part in daily Christian prayer ritual: lawsuit

Brad Reed
June 29, 2022

Woman praying (Shutterstock)

Two former employees of North Carolina-based residential services firm Aurora Pro Services are alleging they were fired for refusing to take part in daily Christian prayer rituals.

Local news ABC News 11 reports that the lawsuit, which was filed by the Equal Employment Opportunity Commission on behalf of employees John McGaha and Mackenzie Saunders, alleges that daily prayer meetings at the company were mandatory and that continued employment at the firm was contingent upon attendance.

The two employees allege that the prayer meetings initially were short 15-minute sessions, but that they gradually grew longer and stretched out to lengths of up to 45 minutes.

Among other things, the leaders of the sessions would seek prayers for "poor performing employees who were identified by name," the lawsuit claims.

When McGaha, who describes himself as an atheist, complained multiple times about the meetings, he saw his base pay slashed in half before being fired shortly after.

Saunders, an agnostic, similarly said that she did not want to keep attending the meetings and was fired soon afterward on the basis that she was "not a good fit" for the company.