Bottom Nozzle Filter Device for LWR Debris Resistance
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Solution Overview
Problem
Existing debris-filtering devices for light water reactor (LWR) nuclear fuel assemblies face issues such as damage from high-speed debris impact, excessive pressure drop, and increased flowing resistance, which compromise safety and efficiency.
Innovation Solution
A bottom nozzle filtering device with a spliced unit plate structure featuring straight-section flow inlets and outlets, flow subchannels, and a stereoscopic mesh design that controls coolant flow direction and pressure loss, while using stainless steel or austenitic nickel complex alloy plates to enhance durability and reduce pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a debris-preventive plate is used to filter debris in the coolant, then debris filtration is improved, but the plate is damaged by high-speed debris impact
Solution Approach 1:
The filtering device is divided into multiple unit plates arranged in sequence, forming a modular structure. Each unit plate contributes to debris filtration while distributing the impact load, preventing single-point failure and improving overall reliability without compromising strength.
2Reliability
If small circular holes are used in the connection plate to filter large debris, then debris filtration is improved, but pressure loss increases
Solution Approach 1:
The filtering structure transitions from small circular holes to a mesh pattern with optimized opening size, shape, and distribution. This parameter optimization maintains effective debris filtration while minimizing flow resistance and pressure loss through improved fluid dynamics.
3Reliability
If gap clearance between sheets is reduced to increase debris filtering efficiency, then filtration capability is improved, but flowing resistance increases
Solution Approach 1:
Different regions of the filtering device have optimized local characteristics. The mesh structure incorporates varying opening sizes and patterns in different zones, allowing efficient debris filtration in critical areas while maintaining lower flow resistance in regions where filtration pressure is already sufficient.
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 filters debris with low pressure drop and reduced flowing resistance, allowing for staged and classified debris filtration and detention, thereby enhancing safety and operational efficiency by preventing fuel rod damage and minimizing pressure loss.
Implementation Method 1
the flow channel includes a plurality of spaced straight-section flow inlets, and a plurality of spaced straight-section flow outlets, as well as flow subchannels connecting with the straight-section of flow inlets and the straight-section of flow outlets
Data Source
AI summary
The present invention relates to a bottom nozzle filtering device and a debris-preventive bottom nozzle that can be used for a light water reactor (LWR) nuclear fuel assembly. The bottom nozzle filtering device includes a plurality of successively spliced unit plates; a through flow channel is formed between the spliced adjacent unit plates; the flow channel includes a plurality of spaced straight-section flow inlets, and a plurality of spaced straight-section flow outlets, as well as a flow subchannel communicating with the straight-section flow inlets and the straight-section flow outlets; the outlet section of each straight-section flow inlet in the middle splits respectively into two flow subchannels, and the inlet section of each straight-section flow outlet in the middle communicates respectively with the two flow subchannels. The flow direction of the coolant is controlled by the straight-section flow inlet, the straight-section flow outlet, the flow subchannel, etc. to prevent unnecessary eddies forming, making the pressure loss effectively controlled; after a large size debris is stopped, the flow enters the flow subchannel to be filtered again, realizing staged filtering, thus improving the filtering effect.