Control Rod Drive Shaft Unlatching Tool Mechanical Latch

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Solution Overview

Problem

Existing tools for unlatching control rod drive shafts in nuclear reactors pose a risk of accidental drop, leading to potential damage and injury due to unintended actuation of pneumatic mechanisms.

Innovation Solution

A mechanical CRDS unlatching tool with a support assembly and latching assembly that uses movable latch fingers and a pin system within J-shaped and L-shaped slots to securely engage and disengage the control rod drive shaft, eliminating the need for pneumatic mechanisms and preventing accidental drops.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If pneumatic mechanisms are used to actuate latch fingers, then the tool can automatically engage and disengage the control rod drive shaft, but the risk of accidental actuation increases, potentially causing the CRDS to fall out

Engineering Contradiction:

Improveautomatic latching mechanismVSAvoidaccidental drop prevention

Core Design Contradiction:

Extent of automationVSReliability

Solution Approach 1:

The patent replaces pneumatic mechanisms with a purely mechanical latching system. The mechanical latching assembly uses spring-loaded latch fingers that automatically engage with protrusions on the CRDS, eliminating pneumatic actuators and their associated control systems. This mechanical substitution removes the risk of accidental pneumatic actuation while maintaining automatic engagement functionality through spring force.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The mechanical latching system is self-actuating through spring force. When the tool approaches the CRDS, the spring-loaded latch fingers automatically engage with the CRDS protrusions without requiring external pneumatic control. The system serves itself by using the spring's stored energy to both engage and maintain the latched state, eliminating the need for external pneumatic actuation.

Inventive Principle:

Principle #25Self-service

2Reliability

If a mechanical latching system is used, then accidental drops are prevented, but the device complexity increases due to additional mechanical components

Engineering Contradiction:

Improveaccidental drop preventionVSAvoidmechanical components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple functions into a single integrated mechanical latching assembly. The latch fingers, springs, and engagement features are merged into one compact mechanism that simultaneously provides automatic engagement, secure holding, and controlled release. This merging reduces the number of separate components compared to a system with distinct pneumatic actuators, control valves, and mechanical linkages.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The spring-loaded latch fingers are self-actuating and require no external power source or control system. The springs automatically provide the force needed for engagement and maintenance of the latched state, eliminating the need for complex pneumatic control systems, sensors, and actuators. This self-service approach simplifies the overall device while maintaining high reliability.

Inventive Principle:

Principle #25Self-service

3Speed

If pneumatic mechanisms are used, then the operation speed is fast, but the risk of harmful factors increases due to potential CRDS drop and equipment damage

Engineering Contradiction:

Improvelatching operation speedVSAvoidequipment damage risk

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent replaces pneumatic mechanisms with a mechanical spring-loaded system that provides equally fast latching operation. The spring force instantly engages the latch fingers with the CRDS protrusions upon contact, achieving rapid latching without the need for pneumatic pressure buildup. This mechanical substitution eliminates the harmful risk of accidental CRDS drop while maintaining fast operation speed.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The mechanical latching system is designed with spring-loaded latch fingers that gradually engage with the CRDS, providing a cushioning effect that prevents sudden drops. The spring mechanism absorbs any impact or misalignment during engagement, ensuring controlled and safe latching operation that eliminates the risk of equipment damage associated with accidental pneumatic release.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentEP2580762B1Control rod drive shaft unlatching tool

Publication Date: 2018.07.18 WESTINGHOUSE ELECTRIC CORP

Figure 1
Figure 2
Figure 3~4

AI summary

A CRDS unlatching tool (2) includes a support assembly (4) and a latching assembly (6), wherein the support assembly is received within the latching assembly in a manner wherein the latching assembly is moveable relative to the support assembly. The support assembly has a plurality of latch fingers (8) and at least one pin, each of the latch fingers being movable between a latched position wherein the latch finger is structured to engage and hold the CRDS an unlatched position wherein the latch finger is structured to not engage the CRDS. The latching assembly includes a first sleeve member (90) and a second sleeve member (68), the second sleeve member having at least one slot (78), wherein the at least one pin is moveably received within the at least one slot. The latching assembly is movable from a latched state to an unlatched state wherein the latch fingers are actuated by the first sleeve member.