Safety Injection Flashcards
What are the 3 functional areas of the SI system?
emergency core cooling (safety injection), residual heat removal (shutdown cooling), and containment heat removal (containment spray)
How does the safety injection system accomplish emergency core cooling?
by injecting borated water into the RCS to cool the core in the event of a LOCA and maintain flow through the core for extended periods.
Why is borated water injected into the core following a secondary steam line rupture?
to increase shutdown margin. The plant will rapidly cool due to the large amount of steam being drawn off the steam generator. Cold water = reactivity addition, so borated water is added to counter the cold water.
What is the maximum temperature and pressure that shutdown cooling can be installed?
350F and 395 psia
How is the shutdown cooling system used to remove heat from containment following a LOCA?
by shifting the heat exchangers to the recirculation mode
What is the shutdown cooling system also used for during re-fueling?
supplement cooling capacity of the fuel pool cooling system and transfer water between the refueling water tank and the refueling pool.
Is the SI system class or non-class?
CLASS
What does the containment spray system do for us?
a) spray borated water into containment atmosphere during a LOCA or steam line rupture to reduce temp and pressure and limit airborne activity release from containment.
b) remove iodine from containment atmosphere
c) remove heat from containment following a LOCA by shifting HX to the recirc mode
d) provide additional flow during shutdown cooling to maintain cooldown rate at lower temps.
What is meant by a passive component of the SI system?
Refers to the SITs. 4 of them connected to the RCS cold legs lined up ready to inject through check valve if rx pressure < 600psig
Where to HPSI and LPSI initially take a suction from and discharge to?
suction from RWT and discharge to all 4 cold legs. Can be lined up to hot legs.
Draw SI system
include:
RWT, suction lines and valves, containment sumps lines and valves, HPSI pumps with lines and valves, LPSI pumps with lines and valves, Recirc lines and valves for HPSI & LPSI pumps, CS pump, Hot leg injection lines and valves, Cold leg injection lines and valves, and SITs and their valves/lines
What does EW supply in the SI system?
cooling to shutdown cooling heat exchanger
What is the “rumble region” and what pump is affected by it?
The LPSI pump has a rumble region of 2500-3500 GPM and should not be operated in this region. It’s caused by the swirling of water past the pump suction elbow and the swirl of water induced by the pump impeller interacting.
Where does each HPSI pump inject?
to all four cold legs and can be lined up to inject to the hot legs.
How does the HPSI pump increase pressure high enough to inject water into the RCS?
through 8 stages that compound the pressure.
