Recently, the spring‑type vibration isolation system for the turbine‑generator foundation of Unit 3 in Phase II of the San’ao Nuclear Power Plant in Zhejiang, operated by China General Nuclear Power Group, has successfully passed its factory‑level joint acceptance and has been shipped to the site for installation and commissioning. This marks the first time such a system has been supplied domestically, signifying that China has achieved technological self‑reliance and controllability in the field of foundation vibration isolation for nuclear power turbine‑generator sets.

Spring isolators are critical load-bearing components of the foundation baseplate for nuclear steam turbine generator sets, functioning much like a vehicle’s suspension system. They effectively prevent vibration generated during turbine operation from propagating downward, ensuring that the portion of the system below the isolators primarily bears static loads. For a long time, the core technologies underlying spring isolators for nuclear steam turbine generator foundations have been controlled by foreign companies, resulting in persistently high equipment costs and posing risks to supply-chain security and stability.

To accelerate the localization of nuclear power equipment R&D, build a modern industrial chain for “HPR1000” nuclear power equipment, and enhance core competitiveness and safety resilience, under the strategic deployment of China General Nuclear Power Group Co., Ltd. (hereinafter referred to as “CGN”), CGN Engineering Co., Ltd. (hereinafter referred to as “CGN Engineering”) took the lead in collaborating with Changzhou Green Power Machinery Manufacturing Co., Ltd. (hereinafter referred to as “Changzhou Green”). Through joint independent research and development, they overcame key challenges—including the inapplicability of domestic spring design standards, the absence of relevant codes and specifications, and the lack of established benchmarks for fatigue‑equivalent calculations—breaking free from conventional industry paradigms. They successfully developed a contact‑wire compensation structure that effectively enhances spring fatigue resistance, a thermo‑static pressure pre‑treatment process that significantly improves spring relaxation resistance, a precision end‑face finishing process that boosts post‑machining geometric accuracy, and a grouped assembly technique that elevates final product performance. These innovations enabled the efficient establishment of a comprehensive standard system and methodology covering the entire service chain—from design and manufacturing to testing, installation, and operation & maintenance—of domestically developed base‑mounting spring vibration isolation devices for steam turbine generator sets, fully meeting nuclear power design and quality requirements and substantially improving prototype performance metrics. Compared with imported counterparts, this device achieves complete coverage of technical specifications, fully satisfying the vibration isolation needs of the “HPR1000” steam turbine generator set.

After 22 months of research and development, the device passed expert appraisal in August 2025, with the conclusion that it fills a domestic gap and that its key performance indicators have reached the advanced level of comparable international products.

Upon entering the engineering application phase, CGN Engineering and Changzhou Green rigorously enforced quality control. Drawing on the design, manufacturing, and quality assurance requirements of nuclear power projects, they overcame the logistical challenges of mass-producing the equipment and successfully completed the production schedule, thereby providing robust assurance for the high‑quality fabrication and delivery of the components.

Going forward, CGN Engineering and Changzhou Green will continue to collaborate with other partners across the industry chain to iteratively enhance the overall performance of the base‑spring vibration isolation system for steam turbine generators, while actively promoting the industrialization, implementation, and widespread adoption of this product.