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Decontamination System for Research Reactor Facility
The Project
Radioactive impurities can become trapped in the thin oxide layer of the inner piping surfaces and process components of a nuclear reactor. The presence of these impurities can create a radiation hazard for operators or maintenance personnel. Chemical decontamination can be used to dissolve this oxide layer, free up the active impurities, and concentrate them outside of the process system, by means of filtration and ion exchange. Using a patented process from Atomic Energy of Canada, (AECL), Numet designed and supplied a process system to reduce active liquid wastes and decontaminate two "Experimental Loops" of AECL's aging Nuclear Research Reactor.
The Solution
Due to spatial constraints and floor loading limitations, the optimum layout for this installation resulted in four separate skids; one main skid for filtration and ion exchange, one for chemical injection, one for feeding the system with fresh resin, and one for the handling of spent resin.
The main skid is a 30 ton ion exchange unit containing five vessels in a shielded enclosure. The unit is equipped with a replaceable filtration system, a resin characterization system, and process sampling points with coolers. The system is designed for local manual control, and thus has all valve handles extended to the outside of the enclosure through stem seals. All process instrumentation is grouped onto one panel for ease of operation.
The Chemical Injection Skid is equipped with two parallel injection systems; one each for the acid and base reagent. It includes a storage / mixing tank, a mechanical mixer, a heater and a pump.
The Fresh Resin Feed Skid includes one tank for anion resin and one for cation resin. The tanks are pressurized with water and the resin is sluiced into the IX tanks on the main skid.
The Spent Resin Skid receives 55 gal DOT approved drums, which are filled for storage of spent resin. A pressure control system is provided on the skid to prevent over-pressurization of the drums during resin transfer from the main skid. Once in the drum, the system dewaters the resin using compressed air.
Chemical
Injection Skid
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Fresh Resin
Feed Skid
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Spent Resin
skid
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Ion Exchange
Skid
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Project Responsibility Highlights
- ASME pressure vessel design and fabrication
- Sizing and specification of pumps, valves and instrumentation
- Calculation of operating and residual activity levels
- Radiation Shielding design and fabrication
- Vent & drain System design and fabrication
- Structural analysis
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