Nine Mile Quick to Move on Retrofit Answer

Although upgrading and resolving valve challenges can seem expensive, conquering them offers one of the quickest and most effective ways for improving plant efficiency.

Niagara Mohawk experienced this at the Nine Mile Point nuclear plant when a positioner on an existing valve tried to control the reactor’s water level within the 1% range. The positioner was slow to move the valve and when it did, the system’s second signal stopped movement and the valve would bleed off the air in order to move back. Interpreting the valve to have over-shot the 1% change, the system started the process again. It was the valve’s unproductive cycle of chasing this signal that prompted Niagara Mohawk to seek an effective solution by replacing the positioner. After extensive testing at the R&D lab, CCI was able to recommend a replacement positioner that could reduce stroke time to the first movement on a small signal change. This solution ultimately increased the plant’s output by 2 MW.

Experience in retrofit design was a key element in the success of this solution. By working together from conceptual stage to the commissioning and follow-up, the retrofit design team and the engineers at the site were able to immediately improve plant performance, without the expense associated with new valve installation and related piping changes.