SI (Safety Injection)

Question 1

ECCS purpose

Emergency Core cooling system

Answer 1

• Deliver cooling water to the reactor core in the event of a LOCA.
• Limits the fuel cladding temp. and thereby ensures that the core will remain intact with its heat transfer preserved.

Question 2

Actions Caused by an SI signal

Answer 2

• Rx Trip
• EDG startup
• FW Isolation
• AFW auto-start
• Safeguard sequencer actuation
• Phase A
• CV Ventilation isolation
• Control room pressurization
• Closes normal Dampers on HVH-1,2,3,4

Question 3

System flowpaths for injection phase and psig

Answer 3

• Injection from RWST by SI pumps (1500psig)
• Passive Accumulator injection (630psig)
• Injection from RWST by RHR pumps (130psig)

Question 4

At what % in the RWST do we move to Recirculation phase?

Answer 4

-9% in the RWST. Changes from RWST feeding pumps to CV sump feeding pumps via the RHR pumps

Question 5

Long Term Recirculation phase implements at what time?

Answer 5

-11 hours after the LOCA

Question 6

SI signals

Answer 6

• Manual
• Low PZR pressure (1715psig)
• High Differential Steam line pressure (100psid 1/3 Loops)
• High Steam line flow on 2/3 S/Gs (37.25-109% from 20-100%power)
• High CV press (4psig)
• Hi Hi CV press (10psig)

Question 7

Hi-Hi CV pressure causes what?

Answer 7

-CV spray actuation

Question 8

What pumps start on SI signal?

Answer 8

• CV spray pumps (10psig CV)
• RHR pumps
• SI Pumps

Question 9

What Valves reposition on SI signal?

Answer 9

• SI-870A/B(Bit Outlet) open

- RHR-744A/B (RHR cold leg injection) open

Question 10

What valves get the SI signal?

Answer 10

• SI-867A/B (Bit inlets)
• SI-870A/B (Bit outlets)
• SI-841A/B (BIT recirc to BAST)
• SI-865A/B/C (Accumulator Outlets)
• RHR-744A/B (RHR cold leg injection)

Question 11

SI-864 A/B
RWST Discharge valves
location, and when they close?

Answer 11

• Located in SI Pump Room West wall
• Normally open.
• Isolates RWST when below 9%

Question 12

SI-866A/B

Hot Leg Injections from SI pump

Answer 12

• Normally closed
• “Backwards” power. A-MCC6, B-MCC5
• Used after 11 hours after recirc to avoid boron buildup.

Question 13

SI-865A/B/C

Accumulator MOV isolations

Answer 13

• Normally open
• Closed when RCS is cooled down or depressurized for maintenance.
• receive SI signal but don’t reposition

Question 14

RWST

Capacity, Boron concentration and Temp

Answer 14

• 353,000gal
• 1950ppm Boron
• 45-100F

Question 15

How many seconds after SI signal do SI pumps start on sequencer?

Answer 15

-5 secs