Nuclear Waste Management: Risks, Policies, and Global Approaches

In the previous class, the discussion revolved around accidents and fatalities associated with nuclear power, concluding that on a per-kilowatt-hour basis, the impact was not as severe as often perceived. The goal is to integrate this data into an externality calculation for nuclear power, comparing it with other energy sources like coal to determine its overall ranking. However, before doing so, it's crucial to address other externalities specific to nuclear power: nuclear waste and nuclear proliferation.

Nuclear Waste: A Perceived Problem

Nuclear waste is a significant concern for many people. However, from a volume perspective, the amount of spent fuel is surprisingly small. For instance, a single concrete pad can hold all the fuel for a nuclear reactor's entire 40-year lifetime. These storage casks are designed to be extremely robust, capable of withstanding impacts like a train collision or being dropped from operational heights. They even survived the Fukushima floods and fires, though they are not impervious to armor-piercing munitions.

A major concern with both casks and spent fuel pools is the potential for harm if the fuel is dispersed. Spent fuel pools contain the equivalent of many reactor cores, and isotopes like Cesium-137, with a 30-year half-life, remain present in significant quantities for decades. While current protections, such as concrete and chain-link fences, are adequate against minor threats, they are insufficient against a determined, knowledgeable adversary. This raises questions about the long-term security of these sites.

The Challenge of Geologic Disposal

Due to risks like corrosion, longevity, and security, there's a consensus that nuclear waste needs to be stored underground, ideally half a kilometer deep, to eliminate these concerns. This process is known as geologic disposal.

Long-Term Protection Standards

The duration for which this waste needs protection is staggering. The current standard aims for the fuel to be no more toxic than natural uranium ore found in the ground. This level of toxicity is reached after approximately 250,000 years. This timescale is immense, far exceeding the lifespan of most countries, written language, civilized society, and even multiple ice ages. Managing waste over such periods presents an unprecedented challenge.

The US Environmental Protection Agency (EPA) sets specific standards. For the first 10,000 years, the exposure for a "reasonably maximally exposed individual" (someone living directly on the repository and drinking groundwater from it) must not exceed 1/20th of the natural background radiation (150 microsieverts). After 10,000 years, any burst of radionuclides due to catastrophic events cannot exceed 1 millisievert (about 1/3rd of natural background) for the next 1 million years. These stringent standards are mandated by law, stemming from a 1955 report reviewed by the National Academies.

The EPA itself acknowledges the infeasibility of monitoring over such vast timescales, leading to inconsistencies in regulations. While a rule to eliminate the million-year timescale was passed, it was overturned in court because the original law specifically references the hundreds of thousands of years mentioned in the foundational report. This highlights the policy challenges in managing nuclear waste.

Radiotoxicity Definition

The definition of radiotoxicity is complex. It's suspected to be measured per gram of purified radionuclides, rather than per nuclei, though this is not definitively stated. Given the log scale of decay, the precise definition might not significantly alter the overall picture.

Warning Future Generations

The idea of effectively warning future generations about nuclear waste, thousands of years from now, has been explored by serious individuals, including discussions about symbolic markers. However, it's not a primary concern for most policymakers.

IAEA Guidelines for Waste Repositories

The International Atomic Energy Agency (IAEA) provides guidelines for selecting waste repository sites:

• Long-term geologic stability: To minimize seismicity and volcanism over the storage period.
• Low groundwater content and flow: To prevent radionuclide transport over 100,000-year timescales. Water can cause corrosion and facilitate movement of radioactive materials.
• Stable chemical conditions: Preferably a reducing environment, typically found below the water table, to prevent oxidation.
• Good structural properties: The repository should be built in robust materials like granite to prevent collapse.

The US Experience: A History of Political Stalemate

The United States has a long and complex history with nuclear waste disposal, dating back to 1947 when waste from the nuclear weapons program first emerged.

The Lyons, Kansas Fiasco

In 1955, a committee on atomic waste was established, recommending isolation for 600 years and identifying salt beds as the ideal geology due to their dryness, stability, and self-sealing properties. The Atomic Energy Commission (AEC) followed this advice, selecting an abandoned salt mine in Lyons, Kansas. Experiments began in 1959, and initial results were encouraging.

However, the AEC proceeded in secret, without informing the state of Kansas or local communities. When a local newspaper exposed the plan, public reaction was surprisingly mild, largely due to the prevailing "atomic age" optimism and the promise of jobs.

The Kansas State Geological Survey, however, raised serious concerns. They criticized the AEC's "oversimplified view of geology," pointing out:

• Lack of baseline measurements for water ingress.
• Known dissolution of salt at the repository edges due to water.
• Numerous vertical holes drilled through the salt for oil and gas exploration, creating potential leakage channels.
• The plastic deformation of salt, which, while self-sealing, also meant structural instability due to uneven overburden.

The AEC, resistant to criticism, held a press conference in the middle of a scientific conference organized by Kansas, announcing the repository's opening and effectively dismissing further scientific review. This alienated the scientific community and led to political intervention from Kansas officials.

The National Academies, asked to review the plan, offered a nuanced response, stating the plan was "likely safe" but with "outstanding questions." This ambiguity fueled the political conflict. Congressional representatives from Kansas criticized the AEC's "big daddy knows best campaign" and accused them of "playing God."

This political backlash led to Congress pulling most of the project's funding. An oversight committee was formed, mandating that any site must allow for "fully retrievable" fuel. While this offered a temporary political compromise, it created a long-term problem: maintaining an active, open repository indefinitely, which is contradictory to the goal of permanent disposal.

Further technical information from the American Salt Corporation revealed flowing water within the salt and failed solution mining attempts, indicating fissures and connections to aquifers. This contradicted the idea of salt as a perfect natural tank. In 1972, the AEC abandoned the Lyons project, shifting focus to vitrification and glass storage in concrete bunkers.

The Nuclear Waste Policy Act and Yucca Mountain

The Lyons debacle awakened Congress, leading to a decade of legislative attempts to address nuclear waste. The 1982 Nuclear Waste Policy Act was the first successful legislation, establishing key principles:

• Federal responsibility: The Department of Energy (DOE) would provide underground repository storage for civilian nuclear fuel, effectively relieving private industry of this burden.
• Retrievability: Fuel must be retrievable for 100 years, but the repository should otherwise be permanent. This was a compromise to address the conflicting demands of retrievability and permanent closure.
• Size limit: The first repository could not hold all existing civilian waste, ensuring the need for a second site and thus spreading the political burden.
• Congressional site selection: Congress, not the DOE, would choose the final site.
• Funding: A tax of 0.1 cents per kilowatt-hour on nuclear power created the Nuclear Waste Fund, establishing a contract between the DOE and private industry.

The DOE identified three potential sites: a salt bed in Deaf Smith County, Texas; crystalline basalt in Hanford, Washington; and lithified volcanic ash (tuff) at Yucca Mountain, Nevada. These sites were chosen not only for their geology (though some were questionable) but also for their political connections, as all three states had significant DOE investments.

However, the congressmen from Texas and Washington, both powerful figures, did not want their states to host the repository. In a late-night amendment, famously dubbed the "Screw Nevada Bill," they legislated that only Yucca Mountain in Nevada could be evaluated. This amendment remains law today.

Yucca Mountain: A Flawed Choice

The DOE proceeded with Yucca Mountain, despite its geological shortcomings:

• Groundwater issues: Chlorine-36 isotopes indicated rapid rainwater transit into groundwater, creating an oxidizing environment and significant water flow, failing to meet 100,000-year guidelines. The DOE responded by deleting the guideline.
• Seismic activity: Yucca Mountain is in an active earthquake zone, experiencing hundreds of earthquakes. A 1992 earthquake caused significant damage to field offices, and a 1999 earthquake derailed a train, raising concerns about transport safety.
• Lack of natural protection: A presidential review board noted that the mountain itself would provide only 0.008% of the protection, with the rest coming from engineered structures, essentially making the mountain an expensive shed.

The DOE's desperation to make the site work led to a loss of public trust, similar to the Lyons, Kansas situation. The state of Nevada, initially powerless, gained a powerful advocate in Senator Harry Reid, who became Senate Majority Leader and effectively blocked the project.

Of the $20 billion collected from the nuclear waste tax, $12 billion was spent characterizing Yucca Mountain, much of it wasted. President Obama established a Blue Ribbon Commission, which reaffirmed the need for a geologic repository and emphasized consent-based siting. However, the "Screw Nevada Bill" remains law, creating a political stalemate.

The Waste Isolation Pilot Plant (WIPP)

The US does have an operational nuclear waste repository: the Waste Isolation Pilot Plant (WIPP) in New Mexico. This salt mine stores transuranic waste from the nuclear weapons program, not civilian spent fuel. WIPP demonstrates that successful geologic disposal is possible with proper planning and community engagement, taking 20 years from authorization to opening.

The Nuclear Waste Fund and Breach of Contract

The federal government's failure to open a repository means it is in breach of its contract with nuclear power companies. Companies are now suing the government for the costs of managing their waste, with judgments paid from the Judiciary Fund, an unlimited allocation of money. This has created a perverse incentive, where a large industry thrives on suing the government, effectively managing waste through litigation rather than a permanent solution. Billions of dollars have been paid out, creating an interim solution but not addressing the long-term problem.

International Approaches to Waste Disposal

Other countries have made varying progress:

• Finland: Operates Onkalo, a repository in granite bedrock, with a protection horizon of 1 million years. They emphasize moral obligation in their siting process.
• Sweden: Plans to use bentonite clay and copper canisters for 1 million years of protection.
• Canada: Selected a granite site at Lake Wabigoon but has not yet begun construction.
• France: Chosen a clay site, in the regulatory phase, with plans for 150 years of operation and safety standards for hundreds of thousands of years.
• UK: Pursuing a consent-based siting process without a specific site in mind.
• Russia and Japan: Primarily focus on a "closed fuel cycle" or reprocessing.

Reprocessing (Closed Fuel Cycle)

Reprocessing, now often called recycling, aims to reduce repository requirements by separating fission products from actinides.

Radioactivity and Reprocessing

After 10 years, fission products, particularly Cesium-137 and Strontium-90, dominate radioactivity. These decay over hundreds of years. In the long run, actinides (uranium, plutonium, etc.) dominate. Reprocessing removes fission products for separate storage, theoretically easing the burden on the long-term repository. However, storing these fission products above ground contradicts the goal of removing them from the biosphere.

Reprocessing plants, like La Hague, are extremely expensive. The process involves burning uranium fuel in a thermal reactor, reprocessing it to extract uranium, liquid fission product waste, and plutonium. The plutonium is then used to make mixed oxide (MOX) fuel, which is burned in the reactor again. While this improves uranium utilization, it adds complex and risky processing steps.

Historically, countries like the UK and US abandoned reprocessing due to high costs. France, Russia, and Japan continue, with Russia particularly interested in fast reactors for more efficient MOX fuel burning and transuranic reduction.

Uranium Availability and Economics

The original rationale for reprocessing was a perceived scarcity of uranium. However, uranium is more abundant than previously thought, with vast reserves, including in seawater. The cost of uranium contributes only 3-5% to the cost of nuclear power. Even if uranium prices quadrupled, the impact on electricity costs would be minimal.

Reprocessing becomes economically viable only when uranium costs exceed $300 per kilogram, far above current prices (around $30 per kilogram). Even optimistic scenarios for uranium extraction from seawater suggest costs around $300 per kilogram, making reprocessing economically indefensible.

Heat Loading and MOX Fuel

Heat is the limiting factor in repository design. For example, at Yucca Mountain, the temperature between drift tubes must remain below 100°C to prevent water from boiling and causing tunnel collapse. This heat constraint dictates the density of fuel that can be stored.

MOX fuel, while potentially reducing the volume of waste, generates about six times more heat than conventional spent fuel. Since roughly six conventional fuel bundles are needed to create one MOX bundle, the heat loading remains essentially the same, offering no advantage in terms of repository capacity.

As the French government acknowledges, spent MOX fuel would still need to be stored above ground for 150 to several hundred years before being placed in a repository, questioning the overall benefit of reprocessing.