# Has Haiyang 3 Cleared Its Final Pre-Fuel Milestone?

Haiyang unit 3 completed hot functional testing on 13 August 2026, marking the last major commissioning gate before nuclear fuel loading at China's most ambitious large-reactor expansion project. State Power Investment Corporation (SPIC) announced the milestone and stated the company aims to load fuel and connect the unit to the grid before year-end 2026 — a compressed timeline that would represent a meaningful acceleration in China's CAP1000 fleet buildout. The hot tests, executed by [China National Nuclear Corporation](https://smrintel.com/companies/cnnc) subsidiary CNNC Fifth Construction Company, encompassed 11 temperature rise-and-fall test platforms, 53 commissioning test procedures, 308 test chapters, and 30 periodic tests. Several transient tests — including non-nuclear steam turbine start-up and main pump coasting — were completed on the first attempt, which SPIC described as validating the thermal performance, interface fit accuracy, and regulation responsiveness of unit systems. Cold functional testing had already been completed in March 2026.

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## What Hot Functional Tests Actually Verify

Hot functional tests are carried out after cold tests and before fuel loading. Where cold tests confirm leak-tightness of the primary circuit — pressure vessels, pipelines, valves across both the nuclear and conventional islands — hot tests push the reactor coolant system to the temperatures and pressures representative of normal operational conditions, without nuclear fuel present.

At Haiyang 3, the scope was substantial: 308 individual test chapters across 53 commissioning procedures is a high-fidelity verification campaign, not a cursory check. The successful first-attempt completion of transient tests including main pump coasting is operationally significant. Main pump coasting behavior — how reactor coolant pumps decelerate and the resulting flow coast-down — is directly relevant to the AP1000/CAP1000 passive safety case, where natural circulation is the fallback cooling mode under loss-of-power scenarios. First-attempt success suggests the installed systems are performing close to design predictions.

The CAP1000 is China's domestically adapted version of the [Westinghouse](https://smrintel.com/companies/westinghouse) AP1000, incorporating localized components and supply chain while retaining the core passive safety architecture. Haiyang already operates two AP1000 units — the first pair of that design to enter commercial operation globally — giving SPIC's engineering teams a meaningful operational reference baseline against which to benchmark Haiyang 3's commissioning data.

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## Construction Timeline and What Comes Next

State Council approval for Haiyang units 3 and 4 came in April 2021. First safety-related concrete for unit 3's nuclear island was poured in July 2022, and construction of unit 4 began in April 2025. Both units are scheduled to reach full operation in 2027, though SPIC's stated goal of connecting unit 3 to the grid within 2026 implies an ahead-of-schedule finish for that unit specifically.

The sequence from here is straightforward but uncompressible: fuel loading, low-power physics testing to verify [criticality](https://smrintel.com/glossary/criticality) characteristics match design predictions, power ascension testing in staged increments, and finally commercial operation declaration. For a CAP1000, that process typically takes several months from first fuel load to commercial operation — making a late-2026 grid connection plausible if fuel loading begins in the near term.

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## The Broader Haiyang Site Ambition

SPIC's figures for the completed four-unit plant are notable in scale: 40 billion kilowatt-hours of annual generation, which the company says is sufficient to meet the electricity needs of half of Shandong Province's residents. The site plan calls for six 1,000-MWe-class reactors in total, with space reserved for two additional units beyond that — what SPIC terms a "10-megawatt-class nuclear power base" (almost certainly meaning 10,000-MWe class in final configuration). If realized, Haiyang would rank among the largest single-site nuclear installations in the world.

That long-term ambition should be viewed with appropriate skepticism. China has a history of announcing expansive site-level nuclear plans that encounter permitting, financing, or grid-integration delays at later phases. Units 5 and 6 have no announced approval timeline in the source material, and the "future expansion" language around the final two units is aspirational. The nearer-term datapoint — fuel loading at unit 3 before year-end — is the metric worth tracking.

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## Industry Implications

For Western observers tracking China's nuclear build cadence, Haiyang 3's progress is a useful calibration point. The unit went from first safety-related concrete in July 2022 to hot test completion in August 2026 — roughly four years to this milestone. Unit 4, which broke ground in April 2025, is tracking a 2027 operational date, implying a similar or slightly faster schedule.

That construction pace — and the first-attempt transient test results — will be of direct interest to utilities and regulators evaluating the AP1000 design's operational maturity. The [first-of-a-kind (FOAK)](https://smrintel.com/glossary/foak) learning curve on the original Haiyang AP1000 units was steep; by units 3 and 4, SPIC and CNNC appear to be executing with considerably more confidence.

For uranium and fuel market participants: CAP1000 units running on standard LEU fuel add to the medium-term demand picture for Chinese enrichment capacity, reinforcing the trend of China becoming both the world's largest reactor builder and one of its largest enrichment consumers.

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## Key Takeaways

- Haiyang unit 3 completed hot functional testing on **13 August 2026**, clearing the final pre-fuel commissioning milestone
- Testing covered **53 commissioning procedures, 308 test chapters, and 30 periodic tests** across 11 temperature platforms
- All transient tests, including non-nuclear turbine start-up and main pump coasting, passed **on the first attempt**
- SPIC targets **fuel loading and grid connection within 2026** for unit 3; full operation for both units 3 and 4 targeted in **2027**
- The CAP1000 is China's localized AP1000 derivative; Haiyang already operates the world's first two commercial AP1000 units
- The completed four-unit Haiyang plant is projected to generate **40 billion kWh annually**
- The site plan envisions up to **six 1,000-MWe reactors** with space reserved for two further units

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## Frequently Asked Questions

**What is a hot functional test at a nuclear plant?**
Hot functional tests simulate the temperatures and pressures of normal reactor operation without nuclear fuel present. They verify that the reactor coolant system, safety systems, and auxiliary systems perform according to design specifications before fuel is ever loaded. At Haiyang 3, this included turbine start-up and main pump coast-down transients.

**What is the CAP1000 reactor?**
The CAP1000 is China's domestically adapted version of the Westinghouse AP1000 pressurized water reactor. It retains the AP1000's passive safety systems — which rely on gravity and natural circulation rather than active pumps for emergency cooling — while incorporating Chinese-manufactured components. Haiyang units 1 and 2 operate the original AP1000 design.

**When will Haiyang unit 3 enter commercial operation?**
SPIC has stated an aim to load fuel and connect to the grid within 2026, with full commercial operation for both units 3 and 4 targeted in 2027. Post-hot-test steps include fuel loading, physics testing, and a staged power ascension program.

**Who is building Haiyang units 3 and 4?**
The project owner is State Power Investment Corporation (SPIC). Construction and commissioning work was executed by CNNC Fifth Construction Company, a subsidiary of China National Nuclear Corporation.

**What does the Haiyang site ultimately plan to build?**
SPIC has indicated a long-term site plan for six 1,000-MWe-class reactors, with space reserved for two additional future units — a configuration the company describes as a "10,000-MWe-class nuclear power base," though only units 3 and 4 have received State Council approval to date.