Fuel Bundle Flow Limiter for Moisture Carry Over Reduction
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Solution Overview
Problem
High moisture carry over levels at the exit of a fuel bundle in a boiling water reactor lead to increased radiation exposure and turbine blade damage, necessitating a reduction in reactor power and core flow, which results in decreased revenues.
Innovation Solution
A fuel bundle flow limiter with a specific design featuring base sections, channels, vertical webs, and locking tabs is mounted on tie plates to reduce the flow area and control moisture carry over, allowing for selective reduction of incoming water flow to low power bundles, thereby maintaining overall core flow and reducing radiation exposure and equipment damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If water flow to low power bundles is reduced to decrease moisture carry over, then moisture carry over level decreases, but reactor power decreases
Solution Approach 1:
The flow limiter is selectively applied only to low power bundles (peripheral fuel assemblies) while high power bundles maintain normal flow. This localized intervention reduces moisture carry over at affected locations without impacting overall reactor power output.
Solution Approach 2:
The flow limiter device is divided into multiple base sections with individual flow control openings, allowing independent flow modulation for different bundle regions. This enables selective flow restriction to peripheral bundles while maintaining central bundle flow.
2Object-affected harmful factors
If core flow is reduced to decrease moisture carry over, then moisture carry over level decreases, but revenues decrease
Solution Approach 1:
By applying flow limiters only to specific low power bundles rather than reducing core flow uniformly, the solution addresses moisture carry over locally without compromising overall reactor productivity and revenue generation.
Solution Approach 2:
The flow limiter provides partial flow restriction (not complete blockage) to low power bundles, sufficient to reduce moisture carry over to acceptable levels while maintaining enough flow to preserve reactor power and revenue.
3Power
If water flow is increased to maintain reactor power, then reactor power is maintained, but moisture carry over level increases
Solution Approach 1:
High power bundles continue to receive full water flow to maintain reactor power, while flow limiters on low power bundles prevent excessive moisture carry over, achieving both power maintenance and moisture control through differentiated flow management.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively decreases moisture carry over levels at the fuel bundle exit, reducing radiation exposure and equipment damage while maintaining reactor power, thus avoiding revenue losses associated with reduced reactor power.
Implementation Method 1
Water enters a fuel bundle of a boiling water reactor (BWR) as a liquid and exits as steam
Data Source
AI summary
A fuel bundle flow limiter according to a non-limiting embodiment of the present invention may include a plurality of base sections, wherein each of the plurality of base sections has at least one opening. A plurality of channels may separate the plurality of base sections. A plurality of vertical webs may extend from the plurality of base sections. A locking tab may be disposed in at least one of the plurality of vertical webs. By using the flow limiter, the moisture carry over (MCO) level at the exit of the fuel bundle may be decreased, thereby reducing radiation exposure to plant operators and reducing damage to reactor equipment.