Below-Grade Radioactive Capture Media for LWR Severe Accidents

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Solution Overview

Problem

Current nuclear Light Water Reactors (LWRs) face challenges in capturing radioactive materials during severe accidents, as existing filtered venting systems can become overwhelmed, leading to environmental contamination and structural damage, and are costly to maintain.

Innovation Solution

A passive capture system located below-grade with varying media granule sizes and a pump-and-treat process to absorb and concentrate radioactive gases, liquids, and particulates, reducing pressure and preventing uncontrolled releases during beyond-design-basis events.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional wet scrubbing system with charcoal filtering is used to filter radioactive contaminants, then radioactive materials can be captured, but the system becomes expensive and may become overwhelmed during severe accidents

Engineering Contradiction:
Improvecapture effectivenessVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts the filtering function from complex above-grade mechanical systems and relocates it to a simple below-grade media bed. The radioactive contaminants are captured by the media bed directly in the containment structure, eliminating the need for complex wet scrubbing systems and charcoal filters while maintaining capture effectiveness.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces a below-grade media bed as an intermediary substance between the radioactive contaminants and the environment. This media bed passively absorbs and captures radioactive materials through adsorption and absorption mechanisms, providing a simple yet effective filtering solution without complex mechanical systems.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If a filtered vent system is implemented to prevent radioactive release, then environmental contamination is reduced, but the exclusion area size and liability increase

Engineering Contradiction:
Improveenvironmental contaminationVSAvoidexclusion area
Core Design Contradiction:
Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The invention implements preliminary action by providing passive containment and capture capabilities within the existing containment structure before any accidental release occurs. The below-grade media bed is pre-positioned to immediately capture radioactive contaminants upon release, preventing their dispersion into the environment and reducing the need for large exclusion areas.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention converts the potentially harmful radioactive release into a beneficial containment process. By designing the system to passively capture and concentrate radioactive materials within the below-grade media bed, the harmful contaminants are transformed into a manageable form that can be contained in a small area, reducing environmental impact and liability.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If active monitoring and external power are used to operate the capture system, then capture effectiveness is maintained, but operational complexity and power requirements increase

Engineering Contradiction:
Improvecapture effectivenessVSAvoidoperational simplicity
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The invention implements self-service by designing a passive capture system that operates without external power or active monitoring. The below-grade media bed automatically captures and concentrates radioactive contaminants through natural adsorption and absorption processes, eliminating the need for powered equipment, monitoring systems, or operational intervention while maintaining capture effectiveness.

Inventive Principle:
Principle #25Self-service

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 system effectively reduces the liability and size of exclusion areas by capturing radio-toxins below-grade, mitigating major off-site releases and reducing atmospheric dispersion, while being cost-effective and operable without external power.

Implementation Method 1

a below-grade media that offers a controlled absorption of radioactive materials (gases, liquids and particulates) that may be released from primary containment

Methodology Applied
Scientific EffectAdsorption: Adsorption

Implementation Method 2

a below-grade media that offers a controlled absorption of radioactive materials

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 3

the below-grade capture system may concentrate the radioactive materials through a pump-and-treat process

Methodology Applied
Scientific EffectPumping: Pump

Data Source

PatentEP2743932B1Radioactive capture system for severe accident containment of light water reactors
Publication Date: 2018.05.02 GE HITACHI NUCLEAR ENERGY AMERICAS LLC
  • EP2743932B1 patent drawingFigure 1
  • EP2743932B1 patent drawingFigure 2~2C
  • EP2743932B1 patent drawingFigure 3~3A

AI summary

A system (100) and a method for capturing gaseous, particulate and liquid radioactive material released from primary containment (3) of a Light Water Reactor (LWR) during severe accident conditions. The system includes a below-grade media area (4), connected to a reactor pressure vessel (RPV) and portions of primary containment (3), providing varying levels of adsorption / absorption of the radioactive material. The media area (4) is located on-site to offer a passive, self-regulating structure for stabilizing a nuclear reactor. The capture system provides for liquid drainage and gaseous venting of the radioactive material, and a treatment capable of treating the media following stabilization of the reactor.