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A resin with positively charged surface sites capable of exchanging negatively charged ions with aqueous solutions.
Anion resin
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The condition that exists when the demineralizer becomes exhausted, and undesirable impurities are detected in the effluent water.
Breakthrough
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The total amount of impurity cations or anions a particular resin bed is capable of holding.
Capacity
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A resin with negatively charged surface sites capable of exchanging positively charged ions (cations) with aqueous solutions.
Cation resin
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Material suspended in primary cooling water that is produced from the corrosion or wear of metals.
Crud
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The breaking free of corrosion products into the primary coolant system after a mechanical, thermal, or chemical shock.
Crud burst
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The removal of inorganic salts by ion exchange.
Demineralization
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The portion of the resin bead that holds the ions used for exchange.
Functional group
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Portion of the resin bead made of a complex organic polymer (long repetitive chain of individual molecular units joined together).
Insoluble matrix
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The reversible exchange of ions between a liquid and a solid.
Ion exchange
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The amount of impurities that pass through the demineralizer bed during a service run. Because demineralizers cannot completely remove all impurities from a water supply, a tiny amount always “leaks” through.
Leakage
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A demineralizer containing a mixture of anionic and cationic resins.
Mixed bed
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A demineralizer unit that is located in the condensate system between the discharge of the condensate pumps and the first low pressure heater. It is used for continuously demineralizing, the condensate during service.
Polisher
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The chemical used in the regeneration of a resin.
Regenerant
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The chemical treatment of a resin bed to remove impure cations or anions and replace them with desirable cations or anions.
Regeneration
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A long chain polymer that is shaped like a bead and has a large number of either positively or negatively charged surface sites. Each site has an inorganic functional group, such as -SO3, covalently attached to the polymer.
Resin
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The normal operation of a demineralizer during which impurities are removed from a flowing water stream.
Service run
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What is the purpose of ion exchange
To control the purity and pH of water
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Define Ion Exchange
The reversible exchange of ions between a liquid and a solid
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Draw and describe two types of demineralizer resins
- Anion resin: a resin with positively charged surface sites capable of exchanging negatively charged ions (anions) with aqueous solutions
- Cation resin: a resin with negatively charged surface sites capable of exchanging positively charged ions (cations) with aqueous solution.
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Describe a typical ion exchange reaction
- NaCl > H2O > Na+ + Cl-
- NaCl dissociates in water to form Na+ and Cl- ions)
- R-H++R-OH-+Na++Cl- > R-Na++R-Cl-+H++OH-
- H++OH- >< H2O
- Hydrogen and hydroxyl ions react to form water
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How does an ion exchange process control pH
pH is raised by substituting Li for H in a H- OH resin bed
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What is the difference between breakthrough and leakage
- Breakthrough: The condition that exists when the demin becomes exhausted, and undesirable impurities are detected in the effluent water
- Leakage: The amount of impurities that pass through the demin bed during a service run. Because demin cannot completely remove all impurities from a water supply a tiny amount always leaks through
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Explain the drop in conductivity when resin capacity is first exceeded.
Sodium hydroxide is replaced with a less conductive sodium silicate
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Why do we sample both the inlet & outlet of a demin
- In order to determine its performance.
- Demin Factor = Inlet conductivity / Outlet conductivity
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How could DP be used to indicate channeling
If DP goes down this could be a sign of channeling where flow channels are established from the inlet to the outlet of an exchanger
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Discuss Demin performance over time in terms of DP
As demins get clogged DP increases and becomes less effective with reduced flow
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List some effects of resin overheating.(Assume new resin)
- anion resin begins to decompose at 140 oF
- cation resin becomes unstable above 250 oF
- Above these levels exchange capabilities are reduced
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List effects of resin overheating (assume resin is full of impurities)
The decomposition of the resins will enter the RCS. CL- levels would increase, Ion exchange goes down radiation levels increase in the RCS
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