As nuclear facilities worldwide undergo modernization, the need for electric actuators that satisfy stricter safety norms, extreme environments, and space-limited retrofits has intensified. These components are critical for valve operation—and must deliver precision, reliability, and compliance under high temperatures and constrained layouts.
A European nuclear operator approached GRAT with a complex challenge: their valve actuator retrofit required multi-turn control, 1-second opening, and 150°C resistance—all within a severely limited installation footprint. After local suppliers failed to meet these integrated demands, the client turned to GRAT based on our documented expertise in compact and high-performance actuation.
Challenge: Complex Requirements in Confined Conditions
During the initial video conference, the client outlined key requirements: the actuator must fit threaded shut-off valves, comply with European EN nuclear standards, open within one second, and operate continuously for 10 hours at 150°C (including five full open-close cycles). The client also expressed concerns about project feasibility, noting that several local suppliers had declined due to complexity or power compatibility issues.
Approach: Structured Development and Transparent Collaboration
GRAT promptly formed a dedicated customization team, breaking down the requirements into four core modules: size, speed, temperature resistance, and precision, with weekly synchronization meetings established from the start. Early in the process, the client proposed an approach where only the gearbox would be housed internally to improve heat dissipation. However, GRAT’s analysis showed this would introduce rotational error of 45–60 degrees, rendering it unsuitable for zero-deviation nuclear valve control. The team therefore proposed an alternative path.
Execution: Data-Driven Testing and Iterative Optimization
To meet high standards within a limited timeframe, GRAT engineers defined a clear development roadmap centered on optimized motor configuration and a customized limit system, tailored specifically to threaded valve installation. The team built a simulated high-temperature nuclear environment for validation, sharing real-time video and data with the client throughout testing.
- Initial test failure due to lubricant breakdown was resolved with high-temperature specialty grease;
- Motor windings and electronics were upgraded from Class B to Class H insulation, supplemented with custom temperature sensors—keeping the motor within safe operating limits at 150°C;
- Gearbox parameters were iteratively optimized to achieve both 1-second operation and 15N·m torque.
The actuator underwent 1,500 cycles at 60°C and a 10-hour thermal test at 150°C (including five cycles), consistently demonstrating reliability and response under extreme conditions. All results were shared promptly with the client via detailed test reports, ensuring full transparency. The client also expressed strong interest in GRAT’s in-house developed testing equipment.
Outcome: Validated Performance and Ongoing Partnership
Upon sample delivery, the client conducted multiple rounds of high-temperature and rapid-operation tests—all of which were passed successfully. The actuator integrated seamlessly into the existing control system, earning praise for its compact design, responsiveness, and thermal durability. The client subsequently placed repeat orders, indicating intent for long-term collaboration.
Conclusion
This case demonstrates GRAT’s ability to deliver customized nuclear-grade solutions and reinforces its customer-centric approach. It also provides a reference technical pathway for retrofits of aging nuclear units worldwide.
This success further indicates that customized, multi-functional electric actuators will play an increasingly vital role in the intelligent modernization of nuclear, petrochemical, and other high-temperature high-pressure industries. GRAT remains committed to supporting global clients with localized responsiveness, helping overcome challenging operational constraints with safe and efficient automation solutions.
