Protection of a nuclear power station surge arrestor with a wire rope isolator system
The seismic range considered in nuclear power plant design is much more demanding since the Fukushima catastrophe. The challenge was to come up with an alternative solution to the standard spring box to protect equipment in nuclear stations while filtering earth tremors and the transmitted accelerations.
Socitec devised a decoupling system that uses wire rope isolators, justifying its choice with calculations and characterisation tests. The system was qualified for earthquakes on an electrohydraulic shaker unit by the Sopemea laboratory.
The wire rope isolator was chosen because this type of spire-rolled cable possesses considerable elasticity and damping capacities, and significant deformation and dissipation capabilities. The equipment is also unaffected by temperature, humidity and chemical agents and can therefore last as long as the equipment it protects.
SYMOS, dynamic modelling of equipment’s reaction to seismic waves
To produce suspensions for wire rope isolators on a surge arrestor in seismic conditions, Socitec employed SYMOS software to model equipment mounted on isolators, represented by elastic liaisons with properties of stiffness and non-linear isolation.
SYMOS software can be used to integrate different types of isolation models (viscous, dry rubbing, structural, etc.) to obtains highly elaborate models.