Why Choose Precision Forgings for SMR Small Modular Reactors? Technical Analysis of Nuclear Main Pump Pump Casings & Impeller Blanks

With the rapid advancement of modular nuclear power technology, SMR (Small Modular Reactor) has become a key direction for the new-generation global nuclear power industry, thanks to its small footprint, flexible deployment and high safety performance. The main circulating pump serves as the "heart" of the SMR cooling system. As core components of the main pump, pump casings and impeller blanks operate continuously under high-temperature, high-pressure and circulating medium conditions. The stability of these components directly affects the operational safety of small modular reactors.

To meet stringent nuclear power operation standards, pump casings and impeller blanks cannot be manufactured from ordinary castings. They must be produced as precision forgings via forging technology. Meanwhile, heavy-duty construction machinery used for the infrastructure construction, equipment maintenance and overhaul of SMR power stations also creates steady demand for precision forged pressure-bearing components. A complete set of processes including forging forming, property modification by heat treatment and precision machining is critical to guarantee long-term stable operation of SMR nuclear power equipment.

I. Two Major Application Scenarios: Main Pump Components for SMRs & Supporting Forgings for Nuclear Construction Machinery

1. Essential Parts for SMRs: Precision Forgings of Main Pump Core Components – Pump Casings and Impeller Blanks

The main circulating pump in the cooling loop of SMRs transports high-temperature cooling media. Pump casings and impeller blanks are Class 1 pressure-bearing precision forgings.

Forging forming to eliminate internal defects 

Integral forging is carried out with high-quality special alloy steel ingots. A reasonable forging ratio breaks coarse as-cast grains and forms continuous metal flow lines, effectively eliminating hidden defects such as pores, porosity and interlayers. Compared with castings, precision forgings feature greatly improved tensile strength and fatigue resistance, preventing cracking and leakage under long-term high-pressure impact.

Heat treatment to optimize comprehensive mechanical properties

Forged blanks undergo a full range of heat treatment processes including normalizing, quenching & tempering and stress-relief annealing. Hardness and impact toughness are precisely regulated to remove residual forging stress, avoid deformation after subsequent precision machining, ensure sealing performance of pump casings and stable operation of impellers, adapting to alternating working conditions of SMRs.

Machining allowance reserved to meet assembly precision requirements Qualified pump casing blanks and impeller blanks are produced by forging with uniform machining allowance reserved for follow-up CNC precision machining. This ensures dimensional tolerances of sealing surfaces, mounting flanges and fluid profile surfaces to satisfy assembly and long-term operation requirements of main pumps for small modular reactors.

2. Supporting Scenario: Precision Forgings for Construction Machinery in Nuclear Power Construction

A large number of construction machinery including crawler cranes, special transport vehicles and hydraulic equipment are adopted during plant construction, equipment hoisting, maintenance and overhaul of SMR sites. Precision forgings are selected for hydraulic valve bodies, load-bearing supports, high-pressure connecting flanges and other pressure-bearing components of such equipment.

Although these forgings are not directly exposed to nuclear media, they endure long-term heavy load impact and hydraulic high pressure. Forging technology improves structural strength, while heat treatment eliminates processing stress to reduce the risk of component fracture, ensuring reliable continuous operation of construction machinery at SMR construction sites.

II. Forging & Heat Treatment Determine the Quality of Precision Forgings for SMR Main Pump Pump Casings and Impeller Blanks

1. Forging: Foundation of Precision Forging Performance

Custom forging schemes are developed for SMR nuclear main pump pump casings and impeller blanks:

· Control forging temperature and heating cycles to guarantee continuous metal flow lines at complex curved surfaces and wall thickness transition areas;

· Strictly manage forging ratio to avoid property differences between the surface and core of forgings;

· Adopt fixture positioning throughout the process to reduce blank distortion and dimensional deviation and lower losses in subsequent machining.

Ordinary castings easily develop micro-shrinkage cavities inside, which gradually expand under nuclear high-pressure cyclic working conditions and trigger leakage. Precision forgings produced by forging avoid such risks from the raw material forming stage, complying with the high-safety design criteria of SMR small modular reactors.

2. Heat Treatment: Tap the Potential Performance of Forgings

Forged pump casing and impeller blanks carry massive residual stress and uneven hardness distribution, so heat treatment is mandatory:

· Stress-relief annealing: Remove forging stress and prevent component deformation after precision machining;

· Quenching & tempering: Balance strength and toughness to enhance anti-fatigue and anti-impact performance;

· Stabilization treatment: Improve the intergranular corrosion resistance of materials against corrosive media in nuclear power systems.

Test specimens are retained for each batch of forgings for mechanical property testing, and complete heat treatment curve reports are issued to meet audit standards of domestic and overseas SMR nuclear power projects.

III. Core Differences Between SMR Nuclear Precision Forgings and Ordinary Industrial Forgings

1. Stricter acceptance standards: Precision forgings of main pump pump casings and impeller blanks follow nuclear non-destructive testing standards. 100% ultrasonic and magnetic particle inspection is implemented, and any tiny defects lead to scrapping. The sampling inspection criteria for supporting forgings of construction machinery are also higher than those for general mechanical parts.

2. Fully traceable processes: Forging records, heat treatment curves, material spectrum reports and NDT reports are filed uniformly for trace verification by project owners.

3. Special working condition requirements: SMR nuclear power equipment is designed for long service life, so forgings must deliver excellent creep resistance and fatigue resistance; forgings for construction machinery focus on performance under short-term heavy load impact.

4. Higher structural complexity: Impeller blanks feature intricate curved surfaces, and pump casings contain irregular flow channels, raising higher requirements for forging forming technology and blank dimensional precision.

IV. Supply Scope

1. Supporting products for SMR Small Modular Reactors: Precision forgings for main pump core components, including pump casing blanks, impeller blanks, nozzle and flange forgings;

2. Supporting forgings for nuclear construction machinery: Precision forgings such as hydraulic valve body forgings, load-bearing connecting forgings and high-pressure flanges manufactured by forging;

3. Export supporting service: Bulk supply for domestic and overseas nuclear power general contractors and equipment manufacturers. Sandblasting anti-rust treatment and export wooden case packaging are available. Complete inspection documents including NDT test reports, material analysis certificates and heat treatment records can be provided.

V. Conclusion

If you are looking for a supplier of nuclear precision forgings manufactured by forging, and need to purchase pump casing blanks and impeller blanks (core components for main pumps of SMR Small Modular Reactors), or pressure-bearing forgings for construction machinery used in nuclear power projects, we provide one-stop processing services covering forging and heat treatment.

Please send product drawings, working condition parameters, annual purchasing volume, acceptance standards and other documents. We offer free process proposals, sample trial production and accurate quotations. Factory visits are welcome. We deliver one-stop solutions to resolve procurement challenges for special precision forgings for SMR nuclear power applications.