Nuclear Notes is produced by the Breakthrough Institute, and covers the policy, regulation, technology, and business of advanced nuclear energy in the United States and beyond.
Every Thursday, we track what’s really going on in the field: the new rules moving through the Nuclear Regulatory Commission, the advanced reactors moving from design to deployment, the companies going public and the utilities merging, and the executive orders and acts of Congress reshaping how the country builds. We explain not just what happened, but why it matters and how the pieces fit together.
DOE Will Inject Help for Supply Chain
The Department of Energy plans to provide $17.5 billion in low-interest loans to jump-start construction of ten Westinghouse AP1000 reactors, not for the construction projects directly, but for the major components.
The idea is to build up the supply chain for reactor vessels, steam generators, reactor coolant pumps, and other big parts, and to lower the cost of those components by encouraging suppliers to tool up to build multiple copies.
The effort follows President Trump’s announcement in May, 2025, that he wanted ten new large reactors under construction by 2030. The new idea is to finance parts for five twin-reactor projects, like Georgia Power’s two-unit expansion at Vogtle, near Augusta, Ga.
“These conditional loans will play an important role in reviving the supply chain needed for America to once again build large-scale commercial reactors,” said the Energy Secretary, Chris Wright, in a statement. “They will also help accelerate the timeline of building those large-scale reactors by up to three years, lowering construction costs and ensuring the United States is able to deliver on President Trump’s bold and ambitious energy addition agenda.”
Working on multiple copies of identical reactors at the same time could introduce greater flexibility, with the ability to transfer components among projects as construction progress required. Serial development would also help develop a cadre of craft workers and construction managers who could move from project to project. While ten reactors might be under way at one time, their schedules for starting and completion would likely differ.
Interest costs are a major component of nuclear project costs, because nuclear is capital-intensive and because construction loan payments start years before the plant can generate energy and revenue. The Department of Energy plan works out to $1.75 billion per reactor, a modest portion of the building expense.
The announcement did not specify an interest rate, but indicated that Westinghouse had signed letters of intent with seven potential partners. This agreement would fund five.
The AP1000 is a modest departure from current-generation pressurized water technology. Engineers refer to current models as “generation 3,” and the AP1000 as “generation 3+.” Both Gen 3 and Gen 3+ models use water to slow down the neutrons released in fission, to a speed more likely to cause additional fissions, and to move heat from the reactor so it can be converted into electricity. But the AP1000 has fewer critical valves and pumps, and less safety-grade electrical cable, and it relies heavily on natural, fail-proof forces, like gravity and passive heat removal. The letters in the model number stand for “Advanced Passive,” and the number is a rounded-down version of the output in megawatts, which is actually about 1,100.
Reactors in the Energy Department’s Advanced Reactor Demonstration Program have moved away from water, using molten salt or inert gas or other materials as a heat transfer agent, allowing higher temperatures at lower pressures, making construction easier, and generating more useful steam. Such models are known as Gen 4 reactors.
But the AP1000 has a major advantage over more advanced technologies: not only does it have a licensed design, but copies are up and running, and it has detailed blueprints. It still needs major cost reductions, though, to make big market inroads. The Vogtle project is the only one of its kind in the United States so far, but China has built two twin-unit AP1000s, and is now building CAP1000s based on the Westinghouse design.
In a major change, the department said that the projects would be jointly owned by Westinghouse itself and by a utility or other developer. Westinghouse and the developer would each have to put up $500 million before the loan could be issued. The loans will be made to a special purpose entity only after those investments are made. In the past, Westinghouse has been a supplier, not an owner, although it did step in and take a bigger role in finishing the Vogtle project.
Another Non-Utility Entrant
A company called Elementl Power, which describes itself as “an independent developer of utility-scale nuclear power projects,” has announced plans to build up to five GE Vernova Hitachi BWRX-300 reactors at a site about 100 miles southeast of Columbus, Ohio, on the Ohio River. It has already applied to the regional grid operator, the PJM Interconnection, for permission to connect up to 600 megawatts of generation.
The project is in an early stage and its prospects are uncertain, but the proposal itself illustrates the uncertainties around the business model for advanced nuclear energy. Elementl is not a utility, and says that “this project will not be funded through electric customer rates.” That would make it a “merchant” plant, a generator in the deregulated system that sells energy for whatever the market will bear, through auctions run by PJM or by longer-term contract, and rents its power capacity on an annual basis to load-serving utilities that are obligated to secure enough power to supply their customers.
That is the basis on which most new generators earn their keep, but it is not a friendly structure for nuclear plants. One of the weaknesses of the deregulated electric system is that it is supposed to be technology-neutral, but in fact it favors development of power plants with short lead-times and low capital costs–a description of natural gas, not nuclear. All the power reactors now in service were built by utilities that could count on reimbursement from captive customers, not revenue from an auction system, but most of the country has moved to the auction system.
Building a merchant nuclear plant has a challenge: one of the biggest needs is low-cost capital, meaning low interest rates, because the builder has to pay years of interest on the investment as it is built. But an independent generator like Elementl is likely to have to pay higher interest than an established utility. And even the established utilities with strong credit ratings have, thus far, shown great caution about signing up for reactors, leaving the field to a variety of other entities. At the moment, the two leading reactors in the Advanced Reactor Demonstration Program are, respectively, backed by a big chemical company, Dow, and investors led by Bill Gates. And the Dow reactor may mostly supply steam for industrial use rather than just electricity for the grid.
The BWRX-300 is in a slightly different category: Ontario Power Generation, a utility owned by the province of Ontario, is building one and has plans for several more. And the Tennessee Valley Authority, another government utility, would like to build one in Oak Ridge, Tennessee. That could reduce the cost and schedule uncertainties that a subsequent developer would face. Additionally, the BWRX-300, a Small Modular Reactor, is less than one-third the capacity of gigawatt-scale reactors, and thus an individual reactor becomes a smaller and perhaps more achievable project.
Elementl says that it has an “early works agreement” with GE Vernova Hitachi, which greeted the announcement warmly, as did local officials in southern Ohio.
A Second Reactor Reaches Initial Criticality
A little more than a year ago, President Trump set a goal of having at least three new reactors reach “initial criticality” by July 4. A second company, Valar Atomics, has now reached that threshold. Initial criticality, often called zero-power criticality, means sustaining a chain reaction at very low levels, a step that can produce data that validates the design of the core.
Antares Nuclear met the milestone two weeks earlier. More could do so before July 4.
Valar said that its model Ward 250, which is intended to produce 5 megawatts, reached the milestone “as a complete, fully integrated system configured for power operations.”
A Deeper Look at a Fusion Start-Up
Keith LeChien, the chief technical officer of Pacific Fusion, which raised $900 million by late 2024 and plans to deploy a commercial fusion power plant in the mid-2030s, gave some detailed answers to questions from Dan Yurman, author of the blog Neutron Bytes. The company’s fusion system uses electricity pulled from the grid to produce 100-nanosecond pulses to fuse deuterium and tritium. LeChien said the technology would use “components that can be manufactured, tested, serviced, and replaced like industrial equipment.”
“Fusion’s promise is enormous — but it is hard,” LeChien said.
NJ Legislature Unanimously Follows Their Pro-Nuclear Governor
Governors of the northeastern states are falling into line to support nuclear energy. The six New England governors signed a letter pledging to include nuclear in their planning. The governor of New York told the state power authority to develop 1 gigawatt of new nuclear, and the governor of Pennsylvania has pushed to speed up the re-start of Three Mile Island. And in New Jersey, the new governor Mikie Sherrill has also pushed for new nuclear.
Legislative action has been rarer. But a New Jersey assembly committee recently unanimously approved a bill to instruct two state agencies to “procure advanced nuclear energy facilities,” and the legislature in Trenton is moving ahead on other fronts.
Correction
Nuclear Notes last week incorrectly described the coolant in Aalo’s 50-megawatt design. It is liquid sodium.
Subsidizing the output of non-CO2 emitting technologies makes sense pending a tax on net CO2 emissions. Subsidizing one kind of capital cost for one kind of zero-CO2 emitting technology does not.
Why is restacking disabled? Good news should be widely shared.