Gland Steam (GS)

Question 1

What is the preferred source for Gland Steam

Answer 1

The Auxiliary Steam system is the preferred source for supplying the gland seal header, since upon an MSIS signal the gland seal header will remain pressurized from the Auxiliary Steam Cross Tie Header.

The auxiliary steam system is the normal steam supply to the GS system through auxiliary steam supply valve GSN-HV-14.

Question 2

What happens to Gland Steam on A loss of Instrument Air (IA)?

Answer 2

If IA is lost, valves 28A and 28B fail open (gland steam supply valves fail open)

Steam pressure unloading valve (GSN-PV-27) Operated directly from the GS system pressure (steam) OPENS to maintain GS Header Pressure approximately 5 psig. No effect from loss of IA.

Gland Steam Packing Exhauster Drain Tank Level Control Valve (GSN-LV-8):
FAILS CLOSED

Question 3

What are the supply valves for Gland Steam?

Answer 3

Steam regulators control the seal steam supply to maintain header pressure at 4 psig

PV-28A (AOV) regulates AS or MS supply pressure
PV-28B (AOV) regulates LP turbine ninth-stage extraction steam supply pressure
PCV-27 regulates the flow of excess sealing steam to the main condenser