# Are X-energy and TerraPower on Track to Deliver the First ARDP Reactors?

The two flagship projects of the Department of Energy's [Advanced Reactor Demonstration Program](https://smrintel.com/glossary/ardp) moved materially forward this week: [X-energy](https://smrintel.com/companies/x-energy) announced a second $1 billion DOE allocation for its Seadrift, Texas deployment, bringing total federal cost-share to roughly $2.15 billion, while [TerraPower](https://smrintel.com/companies/terrapower) signed engineering, procurement, and construction and commercialization agreements with two major South Korean industrial conglomerates to expand its Natrium program internationally.

Both announcements arrived within days of each other in mid-August 2026, signaling that ARDP's two lead developers are simultaneously pushing through regulatory, commercial, and supply-chain milestones — not sequentially, as critics have long feared FOAK nuclear projects tend to do.

The combined picture: more than $2 billion in federal funds now committed to a single four-reactor pebble-bed deployment at an active chemical manufacturing site, and a sodium-cooled fast reactor program that just recruited a tier-one Korean EPC contractor to build up to eight units with completion, price, and performance guarantees. Neither development is a press release placeholder — both carry hard commercial and regulatory deliverables attached.

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## X-energy's Seadrift Project Now Carries $2.15 Billion in DOE Backing

During its second-quarter earnings call on August 14, X-energy CEO Clay Sell disclosed that the DOE had notified the company it would receive an additional $1 billion in cost-shared funding for the Long Mott project — the regulatory designation for the company's plan to build four Xe-100 pebble-bed high-temperature gas-cooled reactors at Dow's UCC Seadrift Operations chemical production facility in Seadrift, Texas.

Combined with the $1 billion already received, total DOE cost-share now stands at approximately $2.15 billion, Sell confirmed. The new tranche carries the same cost-share requirements as the earlier allocation, meaning X-energy must match a defined portion of expenditures with private capital.

The project's significance extends beyond the funding figure. Seadrift would be the first advanced reactor deployment of its kind at an industrial site in North America. The Xe-100 is designed to produce both electricity and high-temperature process heat — exactly what Dow's chemical manufacturing operations require. If completed, it would establish the first real-world LCOE data point for nuclear-supplied industrial process heat in the U.S., a benchmark the entire industrial decarbonization market is watching.

### NRC Construction Permit Timeline: Late 2026 Review, H1 2027 Decision

On the regulatory front, Sell told investors the NRC is expected to complete its [construction permit](https://smrintel.com/glossary/construction-permit) review for Long Mott later this year, with a permit issuance decision likely in the first half of 2027. That schedule, if held, would keep the project inside the original ARDP demonstration window — though FOAK regulatory timelines have a well-documented tendency to slip when technical review questions multiply.

X-energy also expects to submit its construction permit application for the Cascade Advanced Energy Facility in Washington state — a project developed with Amazon and Energy Northwest — in the first half of 2027. That application, once filed, will begin a separate NRC review clock.

### Unnamed Utility Deal "In the Near Future"

Sell also flagged an imminent announcement of a 1-GW project with an unnamed utility. No counterparty, technology configuration, or site was disclosed. At face value this is speculative — but the 1-GW figure is notable: X-energy's Xe-100 is rated at roughly 80 MWe per unit, meaning a 1-GW commitment implies approximately 12 or more reactors. If the deal firms up, it would represent the largest single Xe-100 order announced to date and would substantially change X-energy's commercial backlog profile.

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## TerraPower Signs Korean EPC and Commercialization Agreements for Natrium

TerraPower's commercial strategy crystallized this week with two parallel agreements targeting the South Korean industrial and construction ecosystem — a deliberate move to pair its advanced reactor IP with Korea's proven nuclear EPC execution capability.

TerraPower has reached an agreement with **Hyundai Engineering Construction (HDEC)** under which HDEC will serve as engineering, procurement, and construction contractor and will build up to eight Natrium reactors, with completion, price, and performance guarantees attached. That contractual structure — fixed-price, performance-guaranteed EPC for nuclear — is rare and significant. It shifts a defined portion of construction cost risk to the contractor, a structure that has proven elusive for Western nuclear new-builds for two decades.

The Natrium reactor currently under construction in Kemmerer, Wyoming is a 345-MWe sodium-cooled fast reactor with molten salt heat storage capable of temporarily boosting power output to 500 MWe — a [load-following](https://smrintel.com/glossary/load-following) capability designed to complement variable renewable generation on the grid.

### SK Innovation Agreement Opens Korea's First Natrium Plant

Separately, TerraPower's term-sheet agreement with **SK Innovation** clears a pathway for Korea's first Natrium plant and establishes a framework for international expansion. The two companies will also explore collaboration on digital twin technology and artificial intelligence applications for plant operations — areas where Korea's large engineering firms have invested heavily.

The diplomatic groundwork was substantial: TerraPower founder and chair Bill Gates and president and CEO Chris Levesque traveled to South Korea and met with Prime Minister Seong-sook Han, as well as leaders from the Export-Import Bank of Korea, HD Hyundai, HDEC, and SK Innovation. The Export-Import Bank of Korea's involvement in those discussions is worth monitoring — Korean EXIM financing has historically been a competitive tool for Korean nuclear exports globally, and if it attaches to international Natrium projects, it would give TerraPower a financing instrument that U.S. competitors currently lack.

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## Industry Trajectory: What These Moves Signal

The simultaneous maturation of both ARDP lead projects in the same week is not coincidental — both teams are aware that 2026 and 2027 are make-or-break years for demonstrating that the U.S. can actually build advanced reactors, not just license and fund them.

Several structural observations are worth flagging for industry watchers:

**EPC risk allocation is finally being addressed.** The HDEC agreement with performance guarantees represents a more disciplined approach to construction risk than most Western nuclear projects have managed. Korea's nuclear construction track record — including on-time, on-budget completions in the UAE — makes HDEC a credible counterparty. Whether those guarantees hold through a FOAK sodium-cooled build remains the central question.

**Industrial heat is X-energy's differentiated market.** Every other U.S. SMR developer is targeting electricity markets — data centers, utilities, grid stability. X-energy's Seadrift project, if successful, opens a parallel market in industrial decarbonization that has no domestic nuclear precedent. That differentiation matters for capital allocation and for avoiding direct competition with NuScale, Kairos, and Oklo in the same utility customer set.

**HALEU supply remains the common constraint.** [X-energy](https://smrintel.com/companies/x-energy) recently signed an enrichment contract with [Centrus Energy Corp](https://smrintel.com/companies/centrus-energy) covering both [low-enriched uranium](https://smrintel.com/glossary/leu) and [high-assay low-enriched uranium](https://smrintel.com/glossary/haleu) for Xe-100 deployments. TerraPower's Natrium reactor also requires HALEU. Neither project can proceed to fuel load without a verified domestic HALEU supply chain — and that chain is still being assembled. Any delay in HALEU production capacity will create a hard ceiling on the deployment timelines both companies are publicly committing to.

**Korean partnerships extend U.S. reactor reach.** The HDEC and SK Innovation agreements are not just about building Natrium in the U.S. — they establish a framework for Korea and international markets. If Korea licenses and builds Natrium domestically, it becomes a reference plant for export markets in Southeast Asia, the Middle East, and Eastern Europe, potentially at a speed and cost that U.S. domestic construction alone could not achieve.

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## Key Takeaways

- DOE has committed approximately **$2.15 billion** in total cost-shared funding to X-energy's Long Mott / Seadrift project, following a second $1 billion allocation announced during X-energy's Q2 earnings call.
- The NRC is expected to complete its construction permit review for Long Mott **later in 2026**, with a permit decision likely in **H1 2027**.
- X-energy plans to file a construction permit application for the **Cascade Advanced Energy Facility** (Washington state, with Amazon and Energy Northwest) in **H1 2027**.
- CEO Clay Sell disclosed a **1-GW project with an unnamed utility** is expected to be announced "in the near future" — the scale implies approximately 12 or more Xe-100 units.
- TerraPower signed an EPC agreement with **Hyundai Engineering Construction** to build up to **eight Natrium reactors** with completion, price, and performance guarantees.
- A separate term-sheet with **SK Innovation** creates a pathway for Korea's first Natrium plant and international expansion.
- TerraPower's Natrium reactor in Kemmerer, Wyoming is a **345-MWe** sodium-cooled fast reactor with molten salt storage capable of temporary **500-MWe** output.
- HALEU supply chain development remains the critical shared constraint for both programs' deployment timelines.

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## Frequently Asked Questions

**How much total federal funding has X-energy received for the Seadrift project?**
X-energy CEO Clay Sell confirmed during the company's Q2 2026 earnings call that the DOE's second $1 billion cost-shared allocation brings total federal funding for the Long Mott / Seadrift project to approximately $2.15 billion, under the same cost-share requirements as the initial allocation.

**What is the Natrium reactor and what makes the HDEC deal significant?**
The Natrium is TerraPower's 345-MWe sodium-cooled fast reactor, currently under construction in Kemmerer, Wyoming, with molten salt heat storage that can temporarily boost output to 500 MWe. The HDEC agreement is significant because it includes completion, price, and performance guarantees — a risk-transfer structure that has been largely absent from Western nuclear new-build contracts and covers up to eight Natrium units.

**When will the NRC issue a construction permit for X-energy's Long Mott project?**
According to CEO Clay Sell, the NRC is expected to complete its construction permit review later in 2026, with a permit issuance decision likely in the first half of 2027. NRC review timelines for first-of-kind designs have historically been subject to extension when novel technical questions arise.

**Why is X-energy's Seadrift project important beyond its funding size?**
Seadrift would be the first advanced reactor deployment at an active industrial site in North America, supplying both electricity and high-temperature process heat to Dow's UCC chemical manufacturing operations. If completed, it would establish the first real-world cost and performance data point for nuclear-supplied industrial process heat in the U.S. market.

**What role does HALEU play in both the Natrium and Xe-100 programs?**
Both reactors require high-assay low-enriched uranium fuel. X-energy has signed an enrichment services agreement with Centrus Energy Corp covering both LEU and HALEU for planned Xe-100 deployments. TerraPower's Natrium also requires HALEU. Domestic HALEU production capacity is still being scaled, and supply constraints represent a binding constraint on both programs' stated deployment timelines.