Jet Pump Mixer Diffuser Positioning for Flow-Induced Vibration
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Solution Overview
Problem
Flow-induced vibration (FIV) in boiling water reactor (BWR) jet pumps leads to increased metal fatigue, premature failure, and safety concerns, with existing solutions being costly, complex, and often ineffective, as they require additional parts or alter the flow pattern, which may not alleviate FIV under all conditions.
Innovation Solution
A method that determines the quantitative relationship between the onset of FIV and the mixer/diffuser transverse contact load, positioning the mixer and diffuser to provide the necessary transverse contact load without additional parts or altering the slip joint, using a mixer adjustment device or contact load measuring device to ensure suppression of FIV during reactor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional parts or flow pattern alterations are installed to suppress FIV, then FIV suppression effectiveness is improved, but device complexity and cost increase
Solution Approach 1:
The jet pump system utilizes its own operational characteristics to suppress FIV. By positioning the mixer and diffuser to leverage the existing flow-induced transverse contact load, the system suppresses vibration without requiring external suppression devices or modifications to the slip joint, making the system self-regulating against FIV
Solution Approach 2:
The invention changes the positional parameters of the mixer and diffuser components to optimize the transverse contact load. By adjusting the mixer position relative to the diffuser, the system modifies the flow dynamics and contact load characteristics to suppress FIV, rather than adding physical suppression mechanisms
2Reliability
If additional parts are installed to suppress FIV, then FIV suppression effectiveness is improved, but manufacturing cost increases
Solution Approach 1:
The system uses its own operational characteristics to suppress FIV, eliminating the need for external suppression devices. The existing flow-induced transverse contact load is leveraged to suppress vibration, avoiding additional manufacturing costs for suppression hardware
Solution Approach 2:
The invention extracts and utilizes the beneficial aspect of the flow-induced transverse contact load that naturally occurs in jet pumps. By positioning components to maximize this existing phenomenon, the system achieves FIV suppression without adding expensive suppression hardware
3Reliability
If mixer and diffuser positions are adjusted to provide transverse contact load, then FIV suppression is achieved, but positioning precision requirements increase
Solution Approach 1:
The invention utilizes the dynamic transverse contact load that develops during jet pump operation rather than relying on static positioning alone. The mixer and diffuser are positioned to enable flow-induced contact under operating conditions, allowing the system to adapt to operational dynamics and reducing the stringency of cold-state positioning tolerances
Data Source
AI summary
Flow induced vibration (FIV) at the slip joint between a nuclear reactor jet pump mixer and diffuser is suppressed without installing additional parts or altering the jet pump construction. The disclosed method determines a relationship between reactor operating conditions that trigger FIV and the magnitude of a mixer/diffuser transverse contact load. A mathematical analysis on a representative jet pump configuration determines the quantitative relationship between mixer/diffuser cold positions and their positions when the reactor is operating. Thus, a prediction can be made as to whether an installed jet pump will experience FIV, and the mixer and diffuser can be positioned by a mixer adjustment tool when the reactor is cold to provide the necessary operational transverse contact load. Alternatively, a contact load measuring tool directly measures the magnitude and direction of the cold mixer/diffuser transverse contact load to determine if FIV will be suppressed when the reactor is operating.