Salt concentration in heated crevices and simulated scale. [PWR]
Solutions of NaCl (1 to 125 mg/1) were pumped into an autoclave at 280 C, 64 bar, and boiled in an annular crevice 0.3 mm wide packed (56% porosity) with inert carbon fiber. The weight of NaCl concentrated in the crevice was measured by monitoring the salt concentration in the autoclave outlet after switching off the heater. At constant heat flux, salt accumulated initially at a constant rate determined by the bulk concentration and the rate of evaporation. Accumulation continued at this rate until an equilibrium weight of salt was reached. At constant temperature, the rate of accumulation decreased exponentially as equilibrium was approached. At the constant pressure, the equilibrium weight depended on the temperature of the heat transfer medium and was largely independent of the bulk concentration. Salt was released rapidly when the heater was switched off. A model of the concentration process was developed and applied to the tube/tube support plate crevices in PWR steam generators. Concentration factors in a heated porous layer 2 mm thick were also measured and found to be limited by diffusion or by the temperature of the heat transfer surface.
- Research Organization:
- Central Electricity Research Labs., Leatherhead (UK)
- OSTI ID:
- 5245049
- Report Number(s):
- EPRI-NP-3050; ON: DE84920162
- Country of Publication:
- United States
- Language:
- English
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PWR TYPE REACTORS
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CHEMICAL REACTIONS
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