MSRs

Question 0

Where are the MSRs located?

Answer 0

176’ of the turbine building.

Question 1

What is the purpose of the MSRs?

Answer 1

Improve the quality of the steam exiting the HP turbine before entering the LP turbines.

Drying the steam eliminates erosion of the LP turbine buckets as well as the momentum losses due to excessively moist steam.

Results in more efficiency of the plant and longer LP turbine life.

Question 2

What is the first interaction cold reheat has in the MSRs?

Answer 2

Contacts the chevron plate that removes essentially all entrained moisture.

Question 3

What is unique about the “D” MSR outlet to the LP turbine “C”?

Answer 3

Some hot reheat steam is diverted for use I the main FW pump turbines.

Question 4

Describe the design of the MSR heat exchangers.

Answer 4

2 U-tube two pass.

Question 5

What provides blanketing steam for the reheater tube bundles during shutdown?

Answer 5

Aux steam

Question 6

How does IA interact with the MSR system?

Answer 6

Provides the motive force for operation of low load valves and drain tank level control valves.

Question 7

Where is MSR drain tank discharge directed if level is too high?

Answer 7

To the condenser

Question 8

Where is MSR discharge directed ordinarily?

Answer 8

Heater drain tank.

Question 9

What happens if water in the MSR backs up to within ~3” of the MSR vessel?

Answer 9

A turbine trip is initiated to prevent water induction in the turbine.

Question 10

Where does 1st stage heater condensate drain to?

Answer 10

First to the 1st stage drain tank then to shell side of 6th point heater.

If level is too high to condenser.

Question 11

Where does the 2nd stage heater condensate drain to?

Answer 11

First it goes to the 2nd stage drain tank which then drains to the shell side of the 7th point heater.

If level is too high to condenser.

Question 12

What happens in the MSR drain tanks if a loss of IA occurs?

Answer 12

Normal level control valve will fail closed and the high level. Dump valve will open.

A hi hi level in a heater drain tank causes normal cvs closed

High level control valves fail open on loss of power or air

Normal level CVs fail closed on loss of air or power.

Question 13

How is 1st stage steam flow in the MSRs controlled?

Answer 13

A motor operated reheat stop check valve (RSCV) is operated by a hand switch in the CR

Question 14

How is steam supply to the 2nd stage heaters in the MSRs controlled?

Answer 14

Reheating steam source valves (RSSV) isolates the steam flow

1 Pneumatically operated reheat steam low load valves (RSLLV) & 1 motor operated reheat steam high load valve (RSHLV) work together to regulate steam flow based on MSR and LP turbine operational limits.

Question 15

How are RSHLVs controlled?

Answer 15

Normally automatic but can be manually operated from CR.

Question 16

What happens once the 1st and 2nd stage reheater bundles are placed in service and turbine load is raised above 20%?

Answer 16

The high level dump valve for the 2nd stage drain tank closes and the normal level control valve beignets to maintain level.

Question 17

How is a leak detected in the MSR tube bundles?

Answer 17

Steam pressure decay rate is monitored.

Decay of 50% over one hour= normal

50% decay over 1 minute = leak equivalent of one completely severed tube.

Question 18

Describe how the loss of a MSR would impact the plant.

Answer 18

Would require the shutdown of the unit because they are not isolable from the rest of the system.

Question 19

What stages of reheater bundles can be out of service and still run the MSR?

Answer 19

The second stage can be OOS but the first must be operational. Cannot run with only the 2nd stage reheat.

Question 20

What is the purpose of the MSR relief valves?

Answer 20

Protect MSR from over pressure condition and catastrophic failure.

Relieves outside of the turbine building.

Valves pop open automatically and close automatically when pressure returns to normal.