Hualong One (HPR1000), as China's independently developed third-generation nuclear power technology, relies on its Class 2 and 3 vessels and heat exchangers as critical components ensuring the safe and stable operation of the nuclear power plant. Class 2 equipment primarily serves the specialized safety systems, which activate during hypothetical accident scenarios to prevent radioactive releases and ensure the safe shutdown of the reactor. Class 3 equipment supports the nuclear auxiliary systems, maintaining normal plant operation and basic functions. Due to the unique demands of their application environments, the manufacturing requirements for these components are exceptionally stringent, far exceeding those for conventional petrochemical equipment. The challenges are mainly reflected in the following aspects:

1.Extremely high quality and reliability standards;

2.Stringent material requirements;

3.Complex manufacturing processes with rigorous precision control;

4.Challenges in specialized techniques;

5.Strict inspection and qualification procedures.

Although the Class 2 and 3 vessels and heat exchangers within the nuclear island of Hualong One may not attract as much attention as Class 1 components like the reactor pressure vessel, they are indispensable "unsung heroes" in the nuclear safety defense-in-depth system. Their manufacturing process epitomizes the pinnacle of high-end equipment manufacturing, involving multiple advanced technological fields such as materials science, welding technology, precision machining, and non-destructive testing.

The emergency diesel generator sets in a nuclear power plant are known as the "final power barrier" for nuclear safety, and the main fuel oil storage tank serves as the "energy heart" of this barrier. Its importance is self-evident, and its design and manufacturing standards are exceptionally stringent. The core mission of the main fuel oil storage tank is to store sufficient and reliable fuel for the emergency diesel generator sets, ensuring that the diesel engines can start promptly and operate continuously under extreme conditions. The manufacturing challenges primarily stem from its "nuclear safety-class" classification, which imposes requirements far exceeding those for conventional industrial or commercial fuel storage tanks. These challenges are mainly reflected in the following aspects:

1.Extreme seismic requirements;

2.Demanding environmental and accident condition specifications;

3.Unparalleled quality control and traceability;

4.High standards for cleanliness and fuel protection.
While the main fuel oil storage tank may appear to be a simple container, it is in fact a high-end piece of equipment integrating seismic engineering, anti-corrosion technology, welding processes, and quality control.

Moreover, the emergency diesel generator system is a comprehensive engineering project, with the following three core auxiliary units:
Cooling Unit: Maintains thermal balance during diesel engine operation to prevent overheating.
Fuel Delivery Unit: Ensures a continuous supply of clean, stable, and adequately pressurized fuel to the diesel engine.
Pre-lubrication Unit: Establishes an oil film before diesel engine startup to reduce dry friction, which is critical for ensuring equipment longevity and startup reliability.

As these units serve nuclear safety-class (IE-class) equipment, they must also comply with corresponding nuclear-grade standards.

Zhongyuan—Chashma Nuclear Power Plant Unit C3/C4 Spent Fuel Cooler

The spent fuel cooler is a critical safety device in the back-end fuel cycle of a nuclear power plant, playing an indispensable role, particularly during the off-site storage of spent fuel. Nuclear fuel discharged from the reactor core (i.e., spent fuel) contains a large amount of fission products and exhibits intense radioactivity. These radioactive nuclides continue to decay, releasing significant heat known as "decay heat." Since spent fuel cannot be processed immediately after discharge, it must be cooled for several years or even decades in a strictly controlled environment. The spent fuel cooler acts as a "heat mover" during this process.

Spent fuel is typically stored in spent fuel pools, where water serves as both a shielding and cooling medium. The spent fuel cooler draws pool water via circulation pumps, cools it, and returns it to the pool, forming a closed-loop cycle. This process continuously removes the decay heat released by the spent fuel, ensuring the pool temperature remains within a safe range (typically below 50°C).

The reactor core basket assembly, often referred to as the "skeletal framework of the reactor core," is one of the most critical components among the internal structures of a reactor. It is suspended by its upper flange from the core support ledge of the reactor pressure vessel, while its internal space houses and supports the entire array of fuel assemblies. Positioned inside the reactor pressure vessel and surrounding the fuel assemblies, the core basket serves as a crucial link between the pressure vessel and the core. Its main functions include:

1.Supporting and positioning the fuel assemblies;

2.Forming coolant flow channels and guiding coolant distribution;

3.Providing precise guidance and guide tubes for control rod assemblies;

4.Supporting irradiation samples and surveillance tubes.

Manufacturing such a key component presents immense challenges and represents the pinnacle of heavy equipment manufacturing. The primary difficulties are reflected in the following aspects:

1.Extreme service environment;

2.Stringent material requirements;

3.Large dimensions and exceptionally tight geometric tolerance requirements;

4.Highly complex welding and heat treatment techniques;

5.Advanced machining technology;

6.Strict in-service inspection requirements.

The reactor core basket assembly manufactured by our company has successfully replaced imported products, filling a gap in domestic manufacturing capability for this critical component.

The reactor internals lifting tool is one of the most critical specialized tools used during refueling outages in nuclear power plants. Its precision in design and operation fully reflects the advanced modular and standardized design philosophy of CAP1400/AP1000 technology. Characterized by enormous load-bearing capacity, extremely high safety requirements, precise alignment demands, and specialized connection interfaces, this tool represents a significant engineering challenge due to its complex structure and considerable manufacturing difficulties. Through persistent research and development, our company has successfully achieved the localization of this high-precision equipment.

SNPTC—AP1000 Integrated Reactor Vessel Head Storage Rack

This equipment exemplifies the AP1000 modular design philosophy and optimized outage operation concept, fundamentally transforming the traditional refueling outage approach in pressurized water reactor nuclear power plants. Its core function is to serve as an integrated tool that lifts the reactor pressure vessel head together with all its attached equipment as a single module, transferring it in one piece to a dedicated storage location. This system significantly shortens critical path time during outages, reduces personnel radiation exposure, minimizes the risk of human error, and improves workspace efficiency. The main structure features thick-walled construction, extensive welding requirements, and high precision machining standards. Our company has successfully achieved the domestic production of this advanced tool.

NPIC—SJSG Steam Generator Mock-up and Reactor Coolant Pump Test Vessel

The simulator, or mock-up, serves to create a highly realistic experimental environment outside of an operational nuclear power plant. It is used to study the performance of steam generators and main coolant pumps, verify safety features, train operational personnel, and test new designs. Its manufacturing requirements and materials are referenced from nuclear Class 1 primary equipment in actual nuclear power plants, presenting significant manufacturing challenges.