High-Temperature Permanganate Decontamination of Nuclear Reactor Cooling Systems
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Solution Overview
Problem
Current decontamination methods for nuclear reactor cooling systems require multiple treatment cycles to effectively reduce radioactive surface activity, resulting in high amounts of radioactive waste and increased costs.
Innovation Solution
A method involving multiple treatment cycles with an oxidation step using an aqueous permanganate oxidant solution, followed by a decontamination step with an organic acid, and a cleaning step with an ion exchange resin, where at least one oxidation step is conducted at a high temperature of at least 100 °C, utilizing the reactor coolant pump to circulate and heat the solution, and the residual heat removal system for temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple treatment cycles are used to reduce radioactive surface activity, then the decontamination effectiveness is improved, but the amount of radioactive waste increases and the treatment time increases
Solution Approach 1:
The patent changes the temperature parameter from conventional low temperature to high temperature (autoclave conditions), which fundamentally alters the chemical reaction rates and oxidation efficiency. This parameter change enables achieving the same or better decontamination effectiveness in fewer treatment cycles, thereby reducing radioactive waste generation and treatment time
2Reliability
If multiple treatment cycles are conducted, then the oxide layer removal is more complete, but the application time increases
Solution Approach 1:
The patent applies high temperature (autoclave) conditions that dramatically accelerate the oxidation and dissolution reactions. This enables complete oxide layer removal in a single treatment cycle or fewer cycles, significantly reducing the total application time compared to conventional multi-cycle treatments at lower temperatures
3Ease of manufacture
If conventional decontamination methods are used, then the process is simpler to implement, but the number of treatment cycles required increases
Solution Approach 1:
The patent utilizes autoclave technology which, while requiring specialized equipment, provides controlled high-temperature and pressure conditions that dramatically enhance treatment efficiency. The standardized autoclave process enables achieving complete decontamination in fewer cycles, improving overall productivity despite the need for specialized equipment
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
Significantly increases the decontamination factor, reducing the number of treatment cycles, application time, and radioactive waste generation, leading to cost savings and more efficient oxide layer removal from metal surfaces.
Implementation Method 1
an oxidation step wherein the metal oxides including radioisotopes are contacted with an aqueous solution of a permanganate oxidant
Implementation Method 2
a decontamination step wherein the metal oxides subjected to the oxidation step are contacted with an aqueous solution of an organic acid so as to dissolve at least part of the metal oxides and the radioisotopes
Implementation Method 3
a cleaning step wherein at least the radioisotopes are immobilized on an ion exchange resin
Implementation Method 4
the oxidant solution is kept at a temperature of at least 100 °C and wherein the at least one reactor coolant pump is used to circulate and heat up the oxidation solution
Implementation Method 5
the residual heat removal system is used to control the temperature of the oxidant solution during the high temperature oxidation step
Data Source
Figure 1~2
Figure 3
AI summary
A method of decontaminating metal surfaces in a cooling system of a nuclear reactor comprises conducting a plurality of treatment cycles, with each of the treatment cycles comprising: an oxidation step wherein metal oxides including radioisotopes on the metal surfaces are contacted with an aqueous solution of a permanganate oxidant; a decontamination step after the oxidation step wherein the metal oxides are contacted with an aqueous solution of an organic acid selected from the group consisting of oxalic acid, formic acid, citric acid, tartaric acid, picolinic acid, gluconic acid, glyoxylic acid and mixtures thereof so as to dissolve at least part of the metal oxides and the radioisotopes; and a cleaning step wherein at least the radioisotopes are immobilized on an ion exchange resin; wherein the oxidation step comprises at least one acidic oxidation step and at least one alkaline oxidation step carried out one after another in either the same or different treatment cycles; and wherein the plurality of treatment cycles comprises at least one treatment cycle including a high temperature oxidation step, wherein the permanganate oxidant solution is kept at a temperature of at least 100 °C and, wherein the at least one reactor coolant pump is used to circulate and heat the oxidation solution inside the primary loop, and the residual heat removal system is used to control the temperature of the oxidant solution during the high temperature oxidation step.