Moisture Separator Reheaters Flashcards
What is the purpose of MSRs?
MSRs mechanically remove the moisture content from the HP turbine exhaust steam, and then reheat the exhaust steam to almost the initial HP turbine inlet steam temperature at a much reduced pressure, resulting in superheated conditions
Where does the reheat steam come for the 1st/2nd stage tube bundles in the MSRs?
Steam for the 1st stage reheater tube bundle is supplied from the 2nd stage of HP turbine (U1 - 3rd stage HP turbine)
Steam from the 2nd stage reheater tube bundle is supplied from the MS lines UPSTREAM of the TSVs via a set of PCVs.
How are the MSRs operated during startup? At what specific MWE values are valves repositioned?
During initial startup, MSR system drains are aligned to main condenser
As the turbine is rolled, steam is admitted to 1st stage reheater
U2 – RSLLVs & RSHLVs are placed in AUTO
U1 – RSLLVs are placed in manual prior to beginning pressurization and then transferred to auto after the valves have been opened and pressure stabilized
80 MWe
1st stage reheater drain tank & MSR hotwell drains will auto align from main condenser to FW heaters
MSR hotwell goes to the 7th stage FW Heater
1st stage reheater drain tank to the 4th (5th) stage FW Heater
120 MWe - Steam is admitted to RSLLV & RSHLV of 2nd stage reheater by opening RSSVs (prior to pressurization on U1)
160(170) MWe - 2nd stage reheater drains auto align to the FW heaters - 4th (5th) stage FW heaters
620 MWe
RSLLVs control 2nd stage reheater up to this power
RSLLVs are fully open & RSHLVs will auto open
How are the MSRs operated during shutdown? At what specific MWE values are valves repositioned?
400 MWe - RSHLVs auto close and the RSLLVs will modulate to control 2nd stage pressure
160(170) MWe - 2nd stage reheater drain tank drains auto swap to the main condenser
120 MWe (170 MWe), 2nd Stage RSDVs automatically open
80 MWe - Hotwell drains and 1st stage reheater drain tank drains auto swap to the main condenser
What is the procedural limitation on operation of the 1st and 2nd stage of MSRs?
Procedurally, MSRs cannot be operated w/ 1st stage out of service & the 2nd stage in service
How much of a load reduction will be seen if the 1st and 2nd stage reheaters are removed from service?
Removing the 1st and 2nd stage reheaters from service will result in a load reduction of ~ 6%
Which valves associated with MSRs are air operated? What is the air supply to these valves?
2N38-F006A/B (F102A/B)
RSLLV
Reheat Steam Low Load Valves are air operated
Air supply to air operated valves are Interruptible Essential Air
What are some of the heatup rate limitations associated with the MSRs?
≤ 100°/ hr Rate of change in MSR system
≤ 25°/ 15 min Preferred in Automatic
≤ 25°/ 30 min Preferred in Manual
≤ 150° ▲T Between Main Steam to MSR and temp of first and second stg of MSR
≤ 50° ▲T Between Hot Reheat steam temp of LP turbines
≤ 125°/ hr Rate of change in LP turbine Hot Reheat steam temp
How is water in the MSR, 1st and 2nd stage drain tanks subcooled on unit 1?
- Spray water is added to the MSR, 1st and 2nd stage drain tanks to subcool the condensate ensuring it does not flash prior to entering the downstream heater. (actually a form of water hammer)
- Spray water to the 1st and 2nd stage drain tanks is provided from the RFP discharge.
- Spray water to the MSR drain tank is provided from the condensate booster pump discharge.
