Hydrogen Seal Oil

Question 1

What is the power supply for the Main Seal Oil Pump and the Recirc Seal Oil Pump?

Answer 1

600 MCC “A” (R24-S005) via 600 “B” (600 AA)

Question 2

What is the power supply for the Emergency Seal Oil Pump?

Answer 2

Unit 2 - 125/250 DC Swgr 2D (2R22-S019) via 2R22-S017

Unit 1 - 125/250 DC Swgr 1B (1R22-S017)

Question 3

What are two of the major concerns with Hydrogen escaping the main generator?

Answer 3

• Serious explosive hazard may exist

- Reduced heat removal capability, will force a reduction in generator load

Question 4

When does the emergency seal oil pump auto start? What is different about its flow path?

Answer 4

Auto starts if MSOP discharge pressure ↓ to 95 psig

ESOP only takes suction on the return line, not the Vacuum Tank.

Question 5

Where is Hydrogen seal oil pressure maintained in regards to main generator Hydrogen pressure?

Answer 5

Seal Oil Pressure Regulator 2N42F015 (1N42R752)

• Maintains H2 Seal Oil Pressure 7-9 psig > Main Generator Casing H2 gas pressure
• Compares seal oil pressure to pressure in the Hydrogen Detraining Tank

Question 6

What is the purpose of the hydrogen detraining tank?

Answer 6

Allows large H2 bubbles to escape from the oil draining from the inboard Main Generator Seals.

Question 7

What will happen if the Seal Oil Vacuum pump is out of service?

Answer 7

H2 purity ↓ ~ 2% every 8 hours

Question 8

What would happen if the Main Seal Oil Pump trips, and the emergency seal oil pump fails to start?

Answer 8

• Oil pressure will be supplied from the Main Turbine bearing oil header
• Hydrogen seal oil system pressure will decrease
• Results in the leakage of hydrogen gas from the generator casing to the Turbine Building until Main
  Turbine bearing oil supply pressure is sufficient to provide the shaft seals at the lower hydrogen pressure
• Final hydrogen pressure should stabilize at ~ 25 psig
• Stator cooling water system pressure will decrease to maintain ~ 3 psig below machine gas pressure
• Results in Stator Water press < 25 #, which is setpoint for Main Generator runback on low stator water press
  (happens at Stator water cooling pressure of 35psig for unit 2, 25.6psig for unit 1)

Question 9

What is the purpose of the Recirc Seal Oil Pump?

Answer 9

Recirculates seal oil thru spray nozzles in Vacuum Tank to aid in removal of gases from the oil.
De-aerates and de-hydrogenates in the Seal Oil Vacuum tank