Service Gases (N2/H2)

Question 1

How does the Nitrogen system support Main Steam (SG)?

Answer 1

The SG system receives HP nitrogen gas for pressurizing the atmospheric dump valve accumulators and the backup accumulator for the downcomer feedwater isolation and control valves.

Question 2

What ESFAS signal closes the High Pressure Containment Isolation Valves?

Answer 2

Both the High Pressure and Low Pressure Containment Isolation Valves close upon receipt of a
Containment Isolation Actuation Signal (CIAS).

Question 3

Can the High Pressure N2 Header supply the Low Pressure N2 Header?

Answer 3

Yes, via PV-41

Question 4

What is the pressure of the low and high pressure headers for the N2 system?

Answer 4

115# and 650#
Low pressure header pressure is automatically maintained at 115 PSIG by pressure control valve GAN-PCV-0049. If pressure decreases to 110 PSIG, the backup regulator (GAN-PCV-0049A) begins to supply the low pressure header and maintains pressure at 110 PSIG. If the low pressure nitrogen header pressure decreases to 100 PSIG, the high pressure to low pressure nitrogen pressure regulator (GAN-PC/PV41) begins to supply the lower pressure
header and maintain the nitrogen header at 100 PSIG.

High pressure header pressure is automatically maintained at 650 PSIG. If the high pressure nitrogen pressure decreases to 630 PSIG, the reserve high pressure nitrogen regulator, (GAN-PC/PV-38) will begin to supply the high pressure nitrogen header and maintain pressure at 630 PSIG.

Question 5

What is the cover gas for the Volume Control Tank (VCT)?
Nitrogen or Hydrogen?

Answer 5

Hydrogen maintained ~24#

Question 6

What are the “CSAS 6” ?

Answer 6

Valves tha close on CSAS
3 NC (401, 402, 403 NC Header)
2 Bleedoff (505 and 506)
1 IA UV2