New electric actuators for nuclear service

Jon Lawson

AUMA’s new generation of SAI and SAN electric actuators for nuclear power plants has successfully passed demanding type tests. SAI 07.2 – SAI 16.2 and SAI 25.1 – SAI 35.1 (“inside containment”) actuators are approved to IEEE 382:2006 for use within reactor containment buildings. SAN 07.2 – SAN 16.2 and SAN 25.1 – SAN 35.1 (“outside containment”) series are qualified for service in secondary water, steam, and ventilation systems.

The new actuators are based on AUMA’s latest SA range technology, with polymer components, lubricants and motor windings modified to withstand radiation and high temperatures. For the SAI actuators, ductile cast iron replaces grey cast iron and aluminium as the housing material.

The actuators faced stringent testing to simulate the consequences of steam and coolant leaks, flood, and earthquake. Under such conditions, key valves must remain operable to prevent further damage to the plant.

The SAI type test specimens first underwent thermal ageing to simulate a plant service life of 60 years. They were then submitted to normal service conditions for several months. Finally, the actuators faced simulations of an earthquake and a loss of coolant accident (LOCA), after which they still had to be operable at ambient conditions of 220°C and 6 bar.

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