Monday, August 23, 2010

Valves for Chinese nuclear plants

Emerson Process Management has been awarded two multi-million dollar purchase orders from Westinghouse Electric Company for critical control valves to be used in the first of two AP1000™ pressurised water reactors at both the Sanmen and Haiyang nuclear power plants in China.

Emerson’s Fisher® air-operated control valves will serve several functions related to operational safety in the nuclear containment area. As part of the safety-related system, the valves are engineered to comply with government requirements, including ASME Section III standards for components of nuclear facilities, and undergo rigorous qualification testing at the new Emerson Innovation Center in Marshalltown, (IO, US). The valves' actuators are sized in accordance with EPRI (Electric Power Research Institute) guidelines to ensure adequate operating margins that meet industry standards. To confirm they can operate after a seismic event, they are also designed and tested to survive 6g (6 times gravity) vibration loads in three axes.

In the passive residual heat removal system of the AP1000™ nuclear power plant, Emerson’s Fisher control valves will help achieve proper plant cooling during shutdown. Engineers at Emerson have developed a specially modified ball valve that fits into the limited space available while meeting three key requirements: highly efficient flow during shutdown to provide cooling through a natural convection process without the assistance of the reactor coolant pump; tight shut-off when the plant is in operation to maintain efficiency; and accurate throttling control for all flowing conditions. Extensive testing demonstrated to Westinghouse that the new valve design could meet all specified flow requirements.

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