MSR

Question 1

Describe cold reheat steam flowpath from HP turbine exhaust->LP turbine

Answer 1

• exits HP turbine (~12% moist)
• bottom MSR, MS remove by chevron M.S.’s
• past LP tube bundle (~47 deg super heat)
• past HP tube bundle (~120 deg s.h. Total)
• RSV–>IV–>LP turbine

Question 2

Describe MSR shell side level control

Answer 2

Shell of MSR directed to drain pipe
- level in pipe maintained ~50%, if hi-->#2HDP
(LCV-196, FC)
- level hi-hi dump valve-->condenser 
(LCV-176, FO)

Question 3

Describe flow path of LP heating bundle steam (1st stage reheat)

Answer 3

Extraction steam from HP turbine (3rd stage)

• through non-return valve (FCV-136)
• first pass—>second pass tube bundle
• condensation drains –>LP drain tank
  
  • LCV-164 (FC) maintains ~50% , sends liq–>#2HDT
  • LCV-158 (FO), Hi lvl dumps–>cond
• third pass–>fourth pass –> exits tube bundle
• 100% l/u through FCV- 188(FO) through orifice, increase velocity to cold reheat stm
• S/U l/u through FCV-182—–> condensers

Question 4

Flow path of HP tube bundle heating steam (2nd stage reheat)

Answer 4

Main steam is steam source

• through one of three valves (purge, CV-1 or 2)
• first pass—>second pass tube bundle
• condensation drains –>HP drain tank
  
  • LCV-152 (FC) cntrl ~50%, liq->FW htr1 shell
  • LCV-77 (FO), Hi lvl dumps–>cond
• third pass–>fourth pass –> exits tube bundle
• 100% l/u through FCV- 144 (FO) through orifice, increase velocity to #1 fw htr ext line
• S/U l/u through FCV-194 (FC)—–> condensers

Question 5

Purpose of MSR relief valves

Answer 5

Protect MSR shells if during a turbine Trip the reheat stop and intercept valves close, but not all the control and stop valves close

Question 6

Why is sealing steam supplied to MSR relief valves?

Answer 6

• prevent inadvertent opening at low power/Press

- prevent air in leakage at low power/Press

Question 7

Describe Control scheme for FCV-136, (1st stage reheat supply) non return valve

Answer 7

Air assist open check valve
- when air is removed, acts like normal check valve closing on backflow
- prevents energy flowing backward to turbine
=> stm (no overspeed)
=> wtr (no damage)
(Turbine must be latches to energize valve)
-air removed
-turbine Trip
- hi lvl fw htr (1a, 1b, 1c)
-test
-overspeed protection

Question 8

What is purpose of air oil interface valves?

Answer 8

Supplies instrument air through…
- solenoid valve (able to vent via various trips)
To load……

Valve allows IA to pass through as long as EH oil is pressurized (turbine latched)

=> on turbine Trip, valve vents IA, whatever load is getting air via air/oil interface valve no longer gets it

Question 9

Explain sequence of admitting steam to HP heating bundle

Answer 9

Three valves, purge valve, CV-1, CV-2

Purge- 1” line used for initial warm up

CV-1, 2” line stroked open for 75 deg/hr HUR, LP turbine

CV-2, 6” line opens after CV-1 open 30 minutes

Question 10

When warming up MSR’s what happens when push RAMP?

Answer 10

• CV-1’s open for 75 deg/hr HUR
• after CV-1’s open 30 min CV-2 opens (LP A)… 12 min later LP B opens…..12 min later….
• if demand CV-1 < 98%, CV-2 shut

Question 11

What does 400 deg push button do?

Hot start push button?

Reset push button (on HMI)?

Answer 11

• throttles CV-1 maintain 400 deg in LP T’s
• throttles CV-1 to 400 deg -> LP T’s in 30 sec
• closes CV-1’s, resets timers, cancels previous actions

Question 12

Precautions and limitations for MSR’s

Answer 12

• lose tube bundle Press, must treat MSR cold S/u condition
• ensure sealing steam cut in to MSR relief valves all times (won’t open or leak air in)
• water hammer bad, if happens throttle down