Nuclear Steam Generator Plenum Design for Pressure Stability

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Solution Overview

Problem

Current steam generators in nuclear reactors face challenges in efficiency, ease of manufacture, and safety due to variations in steam generator tube lengths and pressure stability, which can lead to flow instability and turbine performance degradation.

Innovation Solution

A steam generator design featuring multiple plenums arranged in specific planes around a cylindrical riser column with flat tubesheets having varying perforation densities and orifices to stabilize pressure and ensure uniform heat transfer, reducing pressure variations and flow instability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If steam generator tube lengths are varied to improve heat transfer efficiency, then heat transfer efficiency is improved, but pressure stability deteriorates

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidpressure stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by varying the perforation density of tubesheets at different locations. The first tubesheet has a first perforation density while the second tubesheet has a second perforation density, creating localized differences in flow characteristics that compensate for variations in tube lengths and maintain both heat transfer efficiency and pressure stability.

Inventive Principle:
Principle #3Local quality

2Ease of operation

If multiple plenums are added to improve flow distribution, then flow distribution is improved, but device complexity increases

Engineering Contradiction:
Improveflow distributionVSAvoiddevice complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the steam generator into multiple plenums (first plenum, second plenum, third plenum) with distinct functions. Each plenum handles specific flow paths and connects to different tubesheets, enabling improved flow distribution while maintaining manageable complexity through functional modularization.

Inventive Principle:
Principle #1Segmentation

3Speed

If perforation density is increased to improve fluid flow, then fluid flow is improved, but pressure stability worsens

Engineering Contradiction:
Improvefluid flowVSAvoidpressure stability
Core Design Contradiction:
SpeedVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by using different perforation densities in different tubesheets. The first tubesheet has a first perforation density optimized for its location's flow requirements, while the second tubesheet has a second perforation density suited to its location, allowing each region to achieve optimal fluid flow without compromising overall pressure stability.

Inventive Principle:
Principle #3Local quality

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 design enhances pressure stability and uniform heat transfer, reducing the risk of wet steam entering turbines and improving overall reactor performance and efficiency.

Implementation Method 1

coupling thermal energy from a reactor coolant to the at least some of the plurality of flowpaths

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

vaporizing the working fluid in at least some of the plurality of flowpaths, wherein the vaporizing results, at least in part, from coupling thermal energy

Methodology Applied
Scientific EffectPhase change: Phase Change

Data Source

PatentEP2859556B1Steam generator for a nuclear reactor
Publication Date: 2020.12.16 NUSCALE POWER LLC
  • EP2859556B1 patent drawingFigure 1
  • EP2859556B1 patent drawingFigure 2
  • EP2859556B1 patent drawingFigure 3~4

AI summary

A steam generator for a nuclear reactor comprises plenums proximate with a first plane, wherein the first plane intersects a bottom portion of a riser column of a reactor vessel. The steam generator may further comprise plenums proximate with a second plane, approximately parallel with the first plane, wherein the second plane intersects a top portion of the riser column of the reactor vessel. The steam generator may further include a plurality of steam generator tubes that convey coolant from a plenum located proximate with the first plane to one of the plenums proximate with the second plane.