Hydrogen Water Chemistry

Question 1

What are the 3 flow paths to the plant for hydrogen?

Answer 1

1. 250 psig supply from 6 gas storage tubes charged to 1000 to 2000 psig from liquid H2 tank
2. 100 psig supply directly from H2 tank when normal flow path < 100 psig
3. 90 psig from 3 reserves 2000 psig gas storage tubes if first two paths are < 90 psig

Question 2

How much pressure does each oxygen train maintain?

Answer 2

Subsystem A —- 110 psig Oxygen

Subsystem B —- 100 psig

Question 3

What are the 3 types of HWC trips?

Answer 3

Normal Shutdown

H2 immediate trip with Normal O2 shutdown

Emergency trips

Question 4

How does the normal shutdown trip shutdown?

Answer 4

ramps down slowly by INFI-90

Question 5

How does the H2 immediate trip with Normal O2 shutdown, shutdown?

Answer 5

H2 isolates immediately

O2 ramps down, then isolates

Question 6

How does the Emergency trip shutdown?

Answer 6

H2/)2 flow stops immediately

Question 7

What is Nitrogen used for in this system?

Answer 7

pneumatic valves, purge panels to minimize fire hazards

Question 8

what flow rate is H2 maintained at?

Answer 8

15-20 scfm @ 100% power

linear to O2

Question 9

What flow rate is O2 maintained at?

Answer 9

7.5-10 scfm @ 100% power

linear to H2

Question 10

When will excess flow valve auto close for Hydrogen?

Answer 10

> 200 scfm

Question 11

when will excess flow valve auto close for Oxygen?

Answer 11

> 153 scfm

Question 12

When would the excess flow valve need to be bypassed?

Answer 12

when a large amount will be needed.

example, filling generator with H2 on startup

Question 13

What is the power supply to the H2/O2 storage systems?

Answer 13

site power loop subsystem J

Question 14

What powers the logic for the H2/O2 storage system?

Answer 14

1Y99

Question 15

Why is O2 injected into Offgas?

Answer 15

scavenge hydrogen injected into feedwater to prevent explosion in offgas system. it is inserted into offgas at/before the catalytic recombiners

Question 16

Where is oxygen injected at?

Answer 16

Condensate pump suction

Question 17

Why is oxygen injected?

Answer 17

to protect the oxide layer in condensate/feedwater piping

Question 18

Where is hydrogen injected at?

Answer 18

Condensate booster pump bypass line

Question 19

Why is hydrogen injected?

Answer 19

reduce free O2 in Rx minimizing Intergranular Stress Corrosion Cracking (IGSCC) of stainless components inside Rx

Question 20

What are the conditions that cause Hydrogen Immediate Trip with Normal Oxygen Shutdown?

Answer 20

Signal failure
hydrogen detected in Area 1, 113’ by any one of four h2
detectors
CBP bypass flow < 50 gpm
Offgas Oxygen concentration < 6% (both channels)
Offgas hydrogen concentration > 2% (both channels)
Both offgas H2 analyzers OOSVC
INFI-90 H2 controller failure
H2 flow transmitter P73-R003 failure

Question 21

What are the conditions that cause an EMERGENCY TRIP?

Answer 21

** One’s you’re likely to see on test **
BOTH SJAE SUCTION VALVES F003 FULL CLOSED
OFFGAS ISOLATION VALVE F060 NOT FULL OPEN
LOSS OF POWER

(less likely to see on test)
HWC emergency trip HS in trip
HWC system shutdown pushbutton held 5 seconds
INFI-90 oxygen controller failure
oxygen flow transmitter p73-R004 failed
offgas oxygen concentration > 39% (both channels)
one offgas o2 analyzer channel in “high trip” with the
other o2 analyzer in “low trip”
Rx water level of 15” or 50”