Presentation: Event Frames for More Effective Decision Making – a Nuclear MSIV Application

Palo Verde’s Main Steam Isolation Valves (MSIVs) are hydraulically operated and use a high pressure (~5000psi) nitrogen bubble to close in a couple of seconds to isolate the steam generator in the event of a steam line rupture. Stringent pressure requirements force Operators to manually adjust pressure on these valves frequently, so the valve can perform its function. Insulation was installed on the accumulators to see if the pressure swings due to temperature could be dampened. To determine the effectiveness and avoid manual counting, event frames were used to count manual adjustments. Data confirmed that the insulation was effective and helped Palo Verde justify not only moving forward with the project, but investigating advanced insulation materials to make it even better. Event frames and PI Datalink enabled Palo Verde to identify which valves are the worst offenders and most temperature sensitive to so that installation of the insulation can be prioritized as needed.