Suspended Upper Internals Mid-Hanger Plate Nuclear Reactor

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Solution Overview

Problem

Compact nuclear reactor designs face challenges with the complexity, volume, and weight of upper internals, which complicate reactor refueling and maintenance, and introduce potential coolant loss risks due to vessel penetrations.

Innovation Solution

A suspended support assembly using a plurality of hanger plates connected by tie rods, with a mid-hanger plate that engages both internal control rod drive mechanisms and guide frames, allowing for a self-contained unit to be lifted out during refueling, reducing disassembly needs and enhancing maintenance efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If upper internals are mounted directly to the pressure vessel, then structural support is provided, but complexity and weight increase, and vessel penetrations are required

Engineering Contradiction:

Improvestructural supportVSAvoidupper internals complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The upper internals are divided into multiple hanger plates (upper, mid, lower) connected by tie rods, creating a segmented suspended structure. This segmentation reduces the complexity of mounting the entire assembly directly to the pressure vessel while distributing the structural support function across multiple components.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The suspended hanger plate assembly acts as an intermediary structure between the pressure vessel and the upper internals (control rod drive mechanisms and guide frames). This intermediary suspended structure eliminates the need for direct vessel penetrations and reduces overall system complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If upper internals are mounted directly to the pressure vessel, then structural support is provided, but weight increases

Engineering Contradiction:

Improvestructural supportVSAvoidupper internals weight

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

By segmenting the upper internals into multiple hanger plates connected by tie rods, the design distributes weight more efficiently and eliminates heavy direct mounting structures to the pressure vessel, reducing overall stationary weight while maintaining structural support.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The suspended hanger plate assembly serves as a lightweight intermediary structure that provides necessary structural support without requiring heavy direct mounting to the pressure vessel, thereby reducing the weight of stationary components.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If upper internals are mounted directly to the pressure vessel, then structural support is provided, but vessel penetrations are required

Engineering Contradiction:

Improvestructural supportVSAvoidcoolant loss risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The suspended hanger plate assembly acts as an intermediary mounting structure that supports upper internals without requiring direct penetrations through the pressure vessel wall, thereby eliminating the harmful factor of coolant loss through vessel penetrations.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The design extracts the mounting function from the pressure vessel wall by using a suspended structure that hangs within the vessel, removing the need for vessel penetrations and the associated coolant loss risk.

Inventive Principle:

Principle #2Taking out (Extraction)

4Reliability

If upper internals are mounted directly to the pressure vessel, then structural support is provided, but refueling and maintenance complexity increases

Engineering Contradiction:

Improvestructural supportVSAvoidrefueling and maintenance

Core Design Contradiction:

ReliabilityVSEase of repair

Solution Approach 1:

The segmented hanger plate structure allows upper internals to be accessed and maintained more easily during refueling operations, as the modular design enables simpler disassembly and reassembly compared to direct mounting to the pressure vessel.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The suspended hanger plate assembly as an intermediary structure facilitates easier maintenance and refueling operations by providing accessible mounting points and enabling simpler removal and installation of upper internals compared to direct vessel mounting.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9767930B2Suspended upper internals for compact nuclear reactor including a mid-hanger plate

Publication Date: 2017.09.19 BWXT MPOWER INC

AI summary

A pressure vessel comprises an upper vessel section and a lower vessel section. A nuclear reactor core comprising fissile material is disposed the lower vessel section. Upper internals are disposed in the lower vessel section above the nuclear reactor core and are mounted on a suspended support assembly including a plurality of hanger plates connected by tie rods. The upper internals include at least guide frames and internal control rod drive mechanisms (CRDMs) with CRDM motors. The plurality of hanger plates includes a mid-hanger plate that is not the uppermost plate of the plurality of hanger plates and is not the lowermost plate of the plurality of hanger plates. The internal CRDMs are disposed above the mid-hanger plate, the guide frames are disposed below the mid-hanger plate, and the mid-hanger plate engages both the internal CRDMs and the guide frames.