Secondary Chemistry

Question 1

Define GENERAL SG Degradation

Answer 1

Corrosion caused by the presence of Oxygen or Oxygen generating Contaminants

Question 2

Define DENTING SG Degradation

Answer 2

Plastic deformation occurring at the tube support plates

Question 3

Define WASTAGE SG Degradation

Answer 3

Localized corrosion caused by acidic attack in the low flow areas

Question 4

Define PITTING SG Degradation

Answer 4

Localized attack at the sludge sites that may penetrate the S/G tube

Question 5

Define STRESS CORRISION CRACKING SG Degradation

Answer 5

Tube cracking at the S/G U bend caused by chlorides and or stress

Question 6

Define INTERGRANULAR ATTACK SG Degradation

Answer 6

Corrosion of S/G tube grain boundaries at tube sheet crevice or dry out areas

Question 7

Define FRETTING SG Degradation

Answer 7

Local wear from impact or sliding of tubes against support plate or other tubes due to flow induced vibration

Question 8

Define EROSION-CORROSION SG Degradation

Answer 8

Mechanical damage from impingement of SG tubes from suspended corrosion product or reactive chemicals

Question 9

Define FATIGUE SG Degradation

Answer 9

Circumferential tube cracking as a result of cyclic flow or temperature stress

Question 10

State the two functions provided by Hydrazine in reducing secondary plant corrosion

Answer 10

Scavenges Oxygen

Elevates pH

Question 11

Explain why cation conductivity is a better indicator of condenser tube leakage than a standard conductivity measurement

Answer 11

taken after cations have been removed

Provides a very sensitive detection range due to lower “background”

Question 12

State the specific locations sampled for cation conductivity on the High Range Conductivity Recorders located in the Control Room

Answer 12

Total Hotwell
Total Feedwater
SG Blowdown
Feedwater Cation 
Hotwell Cation
MUP Effluent

Question 13

State the Chemistry parameters that are used to set the Limiting Conditions for S/G Operation as set forth by the chemical constituent administrative specifications.

Answer 13

Sodium
Chloride
Sulfate
Cation Conductivity

Question 14

State the final maximum power permitted (long term) when conditions require entry into any of the three (3) action levels for high S/G contamination.

Answer 14

Action Level 1 - 21 days

Action Level 2 - Reduce power to 30 to < 50% within 24 hours

Action Level 3 - <5% power as quickly as safe plant operation permits

Question 15

State one benefit gained from the following considerations when a power reduction is made in response to high S/G contamination: CONCENTRATION RATE

Answer 15

If from tube leak in condenser, it will reduce buildup in crevice areas, and will allow leak to be identified more easily from lower flow.

If the concentration rate is HIGH then extra measures may be required to prevent or minimize damage to the SGs. (increased blowdown)

Question 16

State one benefit gained from the following considerations when a power reduction is made in response to high S/G contamination: RCS HOT LEG TEMPERATURE (T hot)

Answer 16

Intergranular & stress corrosion very temperature dependent.

Analysis has shown that “less damage” occurs at lower RCS Hot Leg temperatures than at elevated temperatures

Question 17

State one benefit gained from the following considerations when a power reduction is made in response to high S/G contamination: S/G HEAT FLUX

Answer 17

Reduced heat flux will reduce hard sludge formation.

As with RCS Hot Leg temps above, the lower the heat flux the less hideout/damage to the S/Gs.