Term
LIST the three reasons for removing impurities from water prior to use in
reactor systems. |
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Definition
1. Minimize Corrosion
2. Minimize Radiation Levels in a Reactor Facility
3. Minimize Fouling of Heat Transfer Surfaces |
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Term
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Definition
| Reversible exchange of ions between a liquid and a solid. Removes undesirable ions from a liquid and substitute acceptable ions from the solid (resin). Accomplished Through Use of a Demineralizer. Process whereby impurities present in the incoming fluid (water) are removed by exchanging impure ions with H+ and OH- ions, resulting in the formation of pure water. |
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Term
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Definition
| Remove minerals from the water. |
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Term
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Definition
| Positive Charge, Exchanges Positive Ions (Ca++, Mg ++, Fe ++) |
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Term
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Definition
| Negative Charge, Exchanges Negative Ions (Cl-, SO4-) |
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Term
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Definition
| Extremely large molecules formed by the combination of many molecules of one or two compounds in a repeating structure producing long chains. |
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Term
| DEFINE Mixed-bed Demineralizer |
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Definition
| Vessel Containing Both Cation and Anion Resin. (Usually with a volume of several cubic feet) |
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Term
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Definition
| Describes the attraction between a resin and a given ion. |
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Term
| DEFINE Decontamination Factor |
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Definition
Measures Ion Exchanger Effectiveness
o DF = Influent concentration/Effluent concentration |
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Term
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Definition
Physically, ion exchange resins are formed in the shape of very small beads, called resin beads, with an average diameter of about 0.005 millimeters.
Wet resin has the appearance of damp, transparent, amber sand and is
insoluble in water, acids, and bases. |
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Term
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Definition
| Designed to exchange positive ions |
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Term
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Definition
| Designed to exchange negative ions |
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Term
| DISCUSS Relative Affinity |
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Definition
| Describes the attraction between a resin and a given ion |
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Term
| DISCUSS Decontamination Factor |
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Definition
Measures Ion Exchanger Effectiveness
Infl concentration, cond or radioactivity
DF = ________________________________
Eff concentration, cond or radioactivity |
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Term
| EXPLAIN the three basic methods used to remove dissolved gases from water |
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Definition
Heat, vent, add chemicals.
1.) Aeration (Vent)
After Passing Through, HCO3
- and H+ Combine To Form Carbonic Acid
Carbonic Acid Readily Dissociates, Aerator Is Used To Remove CO2
H2CO3 ↔ H2O + CO2
2.) Deaeration (Heat)
Water Stored in Vented Tanks Which Contain Electric Heaters or Steam Coils
Water Heated Sufficiently Allowing Slow Boiling
Boiling Strips Dissolved Gases→ Vented To Atmosphere
Effective For Dissolved Oxygen, Other Entrained Gases (CO2, N2, and Ar)
3.) Venting (Vent)
Used Commonly For Reactor System
Usually Accomplished By Venting Steam Space or System high Point
Pressurizer Accomplishes Task in PWR
• Boiling and Stripping Action Causes Stripping To Occur
4.) Addition of Scavengers (Add chemicals)
Hydrogen - 2H2 + O2 2H2O
Conceptually the following is applicable, but not necessarily a learning objective, but it is a chemical that could be added to scavenge:
Hydrazine (N2H4)
Scavenges Oxygen When Plant Temperature <200°F
N2H4 + O2 → 2H2O + N2 |
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Term
| LIST five filtration mediums used to remove suspended solids from water |
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Definition
Pneumonic: SCARE (Jesse is scared of solids in his water)
1) Sand (Sand not normally used in Nuclear Applications)
2) Charcoal (Activated charcoal used following a chlorinator to remove excess residual chlorine and suspended matter).
3) Anthracite
4) Resin in an ion exchanger
5) Earth (Diatomaceous) |
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Term
| EXPLAIN how mixed-bed ion exchangers may be used to control pH. |
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Definition
| Diverting Some of Reactor Coolant through Ion Exchanger Purifies Coolant and Releases OH- => Controlling pH |
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