U2 Main Turbine Cooling/SS/LO

Question 1

What are the U2 MT Trips?

Answer 1

DCS:

• Condenser Vacuum ≤ 20.3” Hg (Manual trip: P8 & , 24.8” Hg
• Overspeed 107%
• Oil # (Bearing) < 14.7# for > 5 sec ***
• Low EHC # 1100#
• Low trip header pressure 2/3 < 800#

Hardwire Trips:

• AMSAC (activated at > 40% pwr, auctates at < 25% FW flow 3/4)
• SI
• SG Hi Hi Lvl at 67% 2/3 on 1 SG (P14)
• Manual
• Overall HEA
• IOPS 110%
• Stator Water (10 second delay)
  - Low Pressure 28 #
  - Low Flow 666 gpm
  - High Temp 95°C (+ 5 second delay)
• Thrust Bearing Wear Abnormal +/-32 mils (axial)
• Unit HEA
• Reactor Trip
• Emergency Trip

Question 2

When does the U2 Turning gear auto start?

Answer 2

• 1 min after Main Turbine Trip.

- Engages when Main Turbine speed < 40 rpm.

Question 3

What are the U2 Turning Gear interlocks?

Answer 3

- Seal Oil ΔP > 7#
One of three bearing oil pumps on:
   - Auxiliary Lube Oil Pump
   - East DC Lube Oil Pump
   - West DC Lube Oil Pump
- Lift pump inlet # > 5 # 
- All Lift Pumps operating
 (If they are the Bypass Interlock Available for Lift Pumps, must be held)

Question 4

When does 2-CMO-40 (Exhaust hood spray) open?

Answer 4

• Generator Load < 7.5%
• Turbine Speed > 900 rpm
• Manual

Question 5

What does the Main Turbine Thrust Bearing do?

Answer 5

• Limits Axial Movement to prevent stationary and rotating blade contact

Question 6

When does the AC Lube Oil pump auto start for the U2 Main Turbine?

Answer 6

• Turbine Trip

- Low Lube Oil # at 16#

Question 7

When do the 2 DC Lube Oil pumps auto start for the U2 Main Turbine?

Answer 7

• Turbine Trip

- Low Lube Oil # at 16#

Question 8

What does LRV-32, LO supply header # Reg Valve, do?

Answer 8

• Maintains U2 turbine supply header # at 24.5# by dumping excess pressure back to the lube oil tank

Question 9

What do the reheat stop and intercept valves do?

Answer 9

• Both Close on Main Turbine Trip to minimize the potential for overspeed of Main Turbine
• Intercept valves throttle to limit overspeed on a load rejection to prevent a turbine trip

Question 10

How do the SRV-26/27, aux steam supply valves fail on U2?

Answer 10

• Fail as is

Question 11

What does SRV-12 (U2 MS Bypass Header supply to steam seals) do?

Answer 11

• keeps HPT Inner Steam Seals 10# > HPT exhaust during normal operation. SRV-12 feeds into a separator tank prior to entering HPT inner seals

Question 12

What supplies LPT Steam Seals during normal operation?

Answer 12

• HP inner seals supply most of steam for seal stm header after it exits the HPT
• Can receive some steam from HP and LP Stop and Ctrl valve leakoff,
• and some aux steam as necessary when HP and LP stop and ctrl valves are backseated

Question 13

What supplies Steam Seals during startup, shutdown and low power operation?

Answer 13

• 50# aux steam supplies steam seals through SRV-22 and SRV-26/27

Question 14

When do the U2 bearing lift pumps auto start?

Answer 14

• Turbine Trip

Question 15

Where in the Lube Oil Flowstream does the DC Emergency Lube Oil Pump discharge?

Answer 15

• Discharge after the Lube Oil Coolers (bypasses them)

Question 16

What effect will long term operation on the DC Emergency Lube Oil pump have?

Answer 16

• Long term operation will cause higher LO temps

Question 17

How do we prevent the MT from tripping on a Rx trip?

Answer 17

• Knife switches are opened to allow turbine to stay on grid when Rx is tripped (prevents turbine overspeed)

Question 18

How do you adjust the Gland Steam Condenser fan?

Answer 18

• adjust blower suction inlet orifice plate (sliding damper) position to 10” vacuum on the Gland Steam Condenser

Question 19

If you lose the glad steam condenser fan, what will happen?

Answer 19

• Steam will leak out turbine and MPF to atmosphere