SDC

Question 1

How many primary purposes does SDC have?

What are they?

Answer 1

3:

1) Cool Reactor from 350F to 140F within 24hr and maintain at 140F
2) Provide heating of Rx Water during heatup/testing
3) Provide additional heat removal to Fuel Pool during refuel outages

Question 2

What are the Limiting components of SDC and what the limits?

Answer 2

The Hx are the limiting components:
Tube side - 1250psig
Shell Side - 150psig
Max Temp 350F

Question 3

Which SDC Mode is required to be available for SDC to be “Operable”?

Answer 3

the cooling loop

Question 4

What flows through the tube side of the SDC HX? Through the shell side?

Answer 4

Tube Side - Rx Water

Shell Side - RBCCW

Question 5

Where is the SDC Suction from? Return to RPV?

Answer 5

Suction from suction side of either RR Loop.

Return to discharge piping of either RR loop using portion of LPCI injection piping

Question 6

How do the SDC Loop configurations for cooldown differ when RPV >212 vs <212?

Answer 6

Cooldown rate controlled differently.
When >212, SDC pp discharge vlv throttled with 3704 vlv full open.
When <212, sdc pp disch. vlv full open w/ 3704 throttled

Question 7

When Rx Water Temp >280F (<350F) what configuration does RBCCW need to be in and why?

Answer 7

To prevent damage to RBCCW Pp via cavitation:
• Rx temp 350 F - 280 F: RBCCW full flow through Hx’s (3300 gpm) and throttle the SDC discharge vlvs
o 1 hx in service – RBCCW valve open for 11 seconds for 3300 gpm through Hx
o 2 hx’s in service – RBCCW valve open for 16 seconds for 6600 gpm through hx’s
o All 3 in service – RBCCW vlv full open, or max Pp amps (<42 amps), or min Pp discharge pressure (50#)

Question 8

When lining up SDC, what configuration of RR is required?

Answer 8

At least one of the RR Pp suction or discharge vlvs must be closed to prevent short cycling SDC flow
If RR Seal Purge maintained, cannot close both

Question 9

What is the general configuration for the SDC Heating Mode?

Answer 9

Same as Cooling mode, but shell of Hx is Heating steam.

Question 10

When SDC on Heating Mode, where does the condensed steam drain to?

Answer 10

RBEDT

Question 11

Which SDC Loop(s) are normally used for Fuel Pool Cooling?

Answer 11

Loop C (all though all can be used)

Question 12

What is the orientation of the SDC Pp Suction and Discharge Vlvs when in FPC mode?

Answer 12

Both Pump Suction and discharge valves are closed and OOS.

Question 13

What can cause inadvertent stratification when using SDC?

Answer 13

When SDC is in operation and NO RR PUMP IN SERVICE - close either RR Pp suction or discharge vlv to prevent SDC short cycle.

RPV Water level

Question 14

What condition, when running SDC, may cause inadvertent draining of the RPV?

Answer 14

If SDC running with LPCI 22 (injection valve) AND either LPCI Test (cooling) or Spray vlvs may cause RPV water to pump to Torus (or DW if DW Spray vlvs open).

Question 15

What are the power sources for SDC Pumps?

Answer 15

2A - 23-1 / 3A - 33-1
2B - 24-1 / 3B - 34-1
2C - 23-1 / 3C - 34-1

Question 16

What powers the RBCCW Supply valve to SDC Hx?

Answer 16

MCC 29-1, 38-1

Question 17

Where are the SDC Min flow valves and what are their normal configuration?

Answer 17

In SDC pump room - Normally L.O.

Question 18

What Are the SDC Isolation valves and their Power Supplies?

Answer 18

1A/B - SDC Suction Isolation - In DW - MCC 28-1

5A/B - SDC Return Isolation - Torus Top - MCC 28-1

Question 19

What are the SDC Pump Valves and their power sources?

Answer 19

Pump Suction Vlv - 2A/B/C - In Pp Rm - 250VDC RB MCC 2A

Pp Disch Vlv - SDC Hx Rm - 4A/B - 250VDC RB MCC 2A (4C - 2B)

Question 20

What are the SDC Pump Vlv Limits and reason?

Answer 20

TO PREVENT RUNOUT:
U2 - Discharge vlvs limited to 60% open or 100psig full flow
U3 - 3A/C - limited to 61% open - 3B limted to 74% or 100psig for full flow

Question 21

What does SDC Pp Discharge Vlv local “STOP” P/B do?

Answer 21

if depressed, removes control power for vlv and stops valve movement IMMEDIATELY - also removes remote capabilities from MCR

Question 22

What are the SDC Isolation signals? what is the logic type? what happens?

Answer 22

Hi Rx Press (~114-115#) - 1 out of 2 twice - Isolation signal to close and/or interlock close all SDC system MOVs
Lo Rx Water at +8” - Grp III Isolation - signal sent to close and/or interlock close all SDC MOVs

Question 23

What are the SDC Pp Trips?

Answer 23

Overcurrent (instantaneous or time delayed)
Bus Undervoltage
Lo Suction Pressure - <4psig for 5-10 sec
SDC Pp Suction Tem >339F

NO VALVES REPOSITION

Question 24

What inadvertent trip can starting SDC cause?

Answer 24

Spurious Grp V isolation due to process noise

Question 25

What happens to SDC with loss of RBCCW?

Answer 25

Loss of cooling to Pp Bearing coolers - secure pp

Cooling medium to Hx lost - must monitor Rx Vessel metal and water temps