Boric Acid Crystal Separation in Nuclear Waste Evaporation
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Solution Overview
Problem
The disposal of boric acid-water mixtures from pressurized water reactors poses environmental and safety challenges due to radioactive contamination, requiring an environmentally friendly, economical, and safe treatment method.
Innovation Solution
A system utilizing a vacuum evaporator and separator to concentrate and separate boric acid crystals from the mixture, with a two-stage evaporation process and subsequent drying, allowing for the separation of radioactively cleaned fractions that can be reused or stored as ordinary waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If boric acid-water mixture is concentrated by evaporation, then boric acid crystals are formed and separated from the mixture, but agglomerates and deposits form on the inner wall of the evaporator
Solution Approach 1:
The system performs preliminary action by dissolving deposited boric acid crystals from the evaporator wall using a dissolving water line before they can form harmful agglomerates. This preventive measure is taken during the evaporation process to maintain clean evaporator surfaces and ensure efficient heat transfer throughout the concentration cycle.
Solution Approach 2:
Dissolving water acts as an intermediary substance that facilitates the removal of deposited boric acid crystals from the evaporator wall. This intermediary fluid dissolves the deposits and transports them away, preventing the formation of harmful agglomerates without interfering with the main evaporation process.
2Ease of manufacture
If boric acid-water mixture is discharged into water body in diluted form, then disposal is simple and economical, but environmental protection requirements are violated
Solution Approach 1:
The system segments the boric acid-water mixture into two distinct fractions through evaporation and separation: a concentrated boric acid crystal fraction and a water fraction. This segmentation allows each fraction to be disposed of or reused according to its specific characteristics, with the water fraction being safe for environmental discharge and the crystal fraction requiring specialized handling.
Solution Approach 2:
The system changes the concentration parameter of the boric acid-water mixture through controlled evaporation. By adjusting the water content and achieving different concentration levels, the mixture is transformed from a diluted state suitable for environmental discharge to a concentrated state where crystals form and can be separated for appropriate disposal or reuse.
3Quantity of substance
If mother liquor is returned to evaporator for reprocessing, then radioactivity is concentrated in fewer fractions, but energy consumption increases
Solution Approach 1:
The system implements feedback by measuring the radioactivity level of the mother liquor and using this information to control the reprocessing decision. A radiation detector monitors the radioactivity concentration, and based on these measurements, the system determines whether the mother liquor should be returned to the evaporator for further concentration or disposed of through alternative routes, optimizing energy usage while ensuring safe radioactivity management.
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 effectively reduces radioactivity in the boric acid crystals, enabling their safe storage or reuse, with no secondary waste and low operational costs, while preventing agglomerate formation in the evaporator and dryer.
Implementation Method 1
the boric acid-water mixture is concentrated by partially evaporating the water in a vacuum evaporator
Implementation Method 2
This suspension is separated into the mother liquor and the crystals in a downstream separator
Data Source
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AI summary
A system and process for separating and processing boric acid from a boric acid-water mixture are proposed. The invention is highly effective, requires no auxiliary materials, and produces no secondary waste. Furthermore, it is easily automated and safe to operate. The system is used for the treatment of radioactive materials/contamination and is suitable for operation in the controlled area of a nuclear facility.