Radioactive Waste Vitrification Using Decay Heat and Graphite
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Solution Overview
Problem
Conventional radioactive waste solidification methods using glass can generate hydrogen gas due to radiolysis, and hydrothermal methods require water, leading to non-uniform vitrified waste with potential radioactive nuclide leakage, while existing glass solidification methods require large melting facilities and are inefficient in time and energy usage.
Innovation Solution
A method involving the use of an adiabatic environment to melt glass raw materials with radioactive waste and graphite, utilizing radiation-generated heat for uniform heating and vitrification, with graphite facilitating efficient heat transfer to reduce production time and prevent non-uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If hydrothermal solidification method is used to melt glass with decay heat, then the need for large melting facilities is eliminated, but water is consumed and the produced vitrified waste is non-uniform with potential nuclide leakage
Solution Approach 1:
The invention extracts and removes water from the solidification process entirely. By using decay heat directly to melt glass in an adiabatic environment without adding water, the method eliminates the source of non-uniformity and potential nuclide leakage while maintaining the benefit of not requiring large melting facilities.
Solution Approach 2:
The invention changes the thermal parameters of the system by creating an adiabatic environment that traps and recycles heat. This allows the decay heat to accumulate and reach the high temperatures needed for glass melting without water interference, ensuring uniform heating and consistent vitrification quality.
2Object-generated harmful factors
If conventional glass solidification method is used, then hydrogen gas generation is avoided, but large melting facilities and long processing time are required
Solution Approach 1:
The invention makes the radioactive waste serve itself by utilizing its own decay heat to melt the glass. This self-heating mechanism eliminates the need for external large-scale melting facilities and accelerates the process, simultaneously avoiding hydrogen gas generation by not using water.
Solution Approach 2:
The invention creates a composite system combining radioactive waste, glass raw materials, and graphite in specific proportions. This composite mixture optimizes heat retention and distribution, enabling rapid and uniform vitrification without external heating equipment or water, thus improving productivity while maintaining safety.
3Loss of time
If adiabatic environment is created to retain heat, then glass melting is accelerated and production time is shortened, but heat distribution uniformity may be affected
Solution Approach 1:
The invention introduces graphite as a thermal intermediary material that facilitates uniform heat distribution throughout the mixture. The graphite conducts heat from hotter regions to cooler areas, ensuring uniform vitrification while the adiabatic environment retains the overall heat energy, achieving both speed and 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
This approach significantly shortens the time to produce a uniform vitrified radioactive waste, reduces the risk of nuclide leakage, and eliminates the need for large melting facilities, enhancing the efficiency and stability of the solidification process.
Implementation Method 1
heating the radioactive waste and glass raw materials existing in the first vessel disposed in an adiabatic area in the second vessel by heat generated by radiation emitted from the radioactive nuclides
Implementation Method 2
heat at the central portion on the traverse plane of the first vessel is transferred to the circumferential portion on the traverse plane through the graphite
Implementation Method 3
disposing the first vessel in which the radioactive waste, glass raw materials, and graphite exist, in an adiabatic area in a second vessel
Implementation Method 4
producing a vitrified radioactive waste by the melt of the heated glass raw materials
Data Source
AI summary
A radioactive waste (zeolite to which Cs-137 was adsorbed) in a waste tank and a glass raw material (soda lime glass) in a glass raw material tank are supplied into a solidifying vessel. Graphite in a graphite tank is also supplied into the solidifying vessel. The solidifying vessel is filled with a mixture of the radioactive waste, glass raw material, and graphite and is then disposed in an adiabatic vessel. The radioactive waste and glass raw material in the adiabatic vessel are heated by thermal energy generated due to radiation emitted from Cs-137. The heat is transferred to the peripheral portion of the solidifying vessel through the graphite, raising the temperature of the peripheral portion. The glass raw material is melted and enters clearances among the radioactive waste, producing a vitrified radioactive waste. This radioactive waste solidification method can shorten a time taken to produce a vitrified radioactive waste.