Nuclear Reactor Wall Drilling for Radioactive Structure Removal

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Solution Overview

Problem

The prolonged dismantling period and increased costs associated with removing nuclear power plant activation structures from reactors due to their buried and radiated nature, requiring high-level technology and complex processes.

Innovation Solution

A method involving the flattening of reactor wall surfaces, installation of drilling devices for dry and wet drilling operations, and subsequent extraction and cutting of activation structures, with a cooling medium collection and purification system to facilitate efficient removal and reuse of the cooling medium.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional drilling methods are used to remove buried activation structures, then the dismantling process can proceed, but the dismantling period is prolonged and costs increase

Engineering Contradiction:

Improvedismantling speedVSAvoiddismantling period

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The drilling operation is divided into two distinct stages: dry drilling to create initial access holes through the reactor wall, and wet drilling to extract the buried activation structures. This segmentation allows each drilling method to be optimized for its specific function, improving overall dismantling efficiency while reducing total time required

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Dry drilling is performed first to create access holes before the wet drilling operation begins. This preliminary action prepares the path for subsequent extraction of activation structures, enabling faster and more efficient removal compared to using a single drilling method throughout the entire process

Inventive Principle:

Principle #10Preliminary action

2Productivity

If cooling medium is used continuously in wet drilling operations, then drilling efficiency is maintained, but environmental contamination and waste generation increase

Engineering Contradiction:

Improvedrilling efficiencyVSAvoidradioactive waste

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The cooling medium is collected after wet drilling operations, subjected to filtration to remove radioactive dust and sludge, and then reused in subsequent drilling operations. This recovery process reduces the generation of radioactive waste while maintaining continuous drilling efficiency, eliminating the need for continuous disposal of contaminated cooling water

Inventive Principle:

Principle #34Discarding and recovering

Solution Approach 2:

A feedback loop is established where the condition of the cooling medium is monitored, contaminated cooling medium is filtered and purified, and the purified cooling medium is fed back into the drilling system. This closed-loop system maintains drilling efficiency while minimizing harmful waste output through continuous purification and reuse

Inventive Principle:

Principle #23Feedback

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 method enables easier dismantling of nuclear power plant activation structures, reducing the dismantling period and cost by stabilizing drilling operations and reusing purified cooling medium, thus enhancing the efficiency and cost-effectiveness of the process.

Implementation Method 1

collecting a cooling medium used in the wet drilling operation using a cooling medium collection unit; transferring the cooling medium collected by the cooling medium collection unit from the cooling medium collection unit to a first water collection tank

Methodology Applied

Scientific EffectFluid collection and transfer:

Implementation Method 2

depositing dust or sludge contained in the cooling medium in a lower portion of the first water collection tank to separate at least a portion of the dust or sludge contained in the cooling medium

Methodology Applied

Scientific EffectSedimentation: Sedimentation

Implementation Method 3

purifying the cooling medium from which the dust or sludge is separated, and resupplying the purified cooling medium to reuse the purified cooling medium as the cooling medium of the second drilling device

Methodology Applied

Scientific EffectFiltration: Filter (physical)

Data Source

PatentUS11862355B2Method of removing radioactive structure from a wall in a nuclear power plant

Publication Date: 2024.01.02 KOREA ATOMIC ENERGY RES INST

AI summary

The present disclosure relates to a method of removing a radioactive structure from a nuclear power plant. The method includes flattening at least a portion of an outer surface of a drilling portion of a wall of a nuclear reactor vessel when the portion of the outer surface is uneven, wherein the radioactive structure is buried in the wall and the drilling portion is adjacent to the radioactive structure, installing a drilling device in the flattened drilling portion and performing a drilling operation, extracting the radioactive structure from the wall, and cutting the extracted radioactive structure and storing pieces of the cut radioactive structure in a shielding container.