Telescoping Guide for In-Core Instrumentation Support
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Solution Overview
Problem
In pressurized water reactors, existing systems lack adequate support and protection for in-core instrumentation above the upper support plate, leading to potential leakage and maintenance challenges, especially during refueling operations, where instrumentation must be withdrawn and the upper internals accessed without impeding coolant flow.
Innovation Solution
The design incorporates axially slidable sleeves and an instrumentation grid assembly that extend above the upper support plate, providing support and protection for in-core instrumentation, with a spiral spring for stability and a telescoping mechanism to ensure the instrumentation is shielded and securely positioned above the upper core plate during reactor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If in-core instrumentation is withdrawn from the core for refueling operations, then the core can be accessed for servicing, but the instrumentation lacks adequate support and protection above the upper support plate
Solution Approach 1:
A slidable sleeve is introduced as an intermediary component between the in-core instrumentation and the upper support plate. The sleeve extends above the upper support plate when the instrumentation is withdrawn, providing the needed support and protection without preventing core access. This mediator structure solves the contradiction by enabling both core accessibility and instrumentation support simultaneously.
2Reliability
If fixed in-core neutron detectors are enclosed in guide paths composed of tubing, then leakage is mitigated, but the instrumentation cannot be withdrawn for core access
Solution Approach 1:
The guide path structure is made dynamic through the slidable sleeve that can extend and retract. When the instrumentation is in place, the sleeve is retracted to allow normal operation. When withdrawal is needed for core access, the sleeve extends to provide guidance and protection throughout the movement, enabling both leakage prevention and instrumentation withdrawal.
3Ease of operation
If upper internals are removed to access the core, then refueling operations can be performed, but coolant flow may be impeded
Solution Approach 1:
The upper internals are segmented into removable components and fixed components. The slidable sleeve and instrumentation can be withdrawn independently through the support columns without removing the entire upper internals package. This segmentation allows core access while maintaining the structural integrity and coolant flow paths of the remaining upper internals.
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
This solution minimizes disassembly requirements for maintenance, prevents vibration, and ensures safe withdrawal and reinsertion of highly irradiated instrumentation, protecting it from damage and maintaining coolant flow integrity during reactor servicing.
Implementation Method 1
a spiral spring for stability
Data Source
AI summary
A telescoping guide for extraction and reinsertion support handling of in-core instrument thimble assemblies in the area above the upper support plate in the upper internals of a pressurized water reactor. The telescoping guides extend between the upper ends of the upper internals support columns and an axially movable instrumentation grid assembly which is operable to simultaneously raise the telescoping guides and extract the in-core instrument thimble assemblies from the reactor fuel assemblies.