What is purpose of SDC?
Removes PCS decay heat during Rx shutdown. Transfers heat from PCS to CCW
Cool PCS from 300°F to refueling temp assuming CCW inlet temperature of 90°F
What are SDC design limits?
SDC Hxs will cool the PCS to 130°F and maintain it at 130°F 27 ½ hours after reactor shutdown with 90°F CCW temperature and a fully irradiated core
Draw and label a one-line diagram of the Shutdown Cooling System showing system interfaces and the following major components:
- P-67A/B, LPSI Pumps
- E-60A/B, Shutdown Cooling Heat Exchangers
- Shutdown Cooling control room operated valves
- RV-0401, SDC Water Return Line Relief
- RV-3164, SDC Suction Relief
Describe power supplies, controls and interlocks for MO-3015/3016.
- Switches at C-33 and Control Room are in parallel, either switch will open/close the valve.
- MO-3015 - MCC-1
- MO-3016 - MCC-2
- PS‑0104A - MO-3015
- PS‑0104B - MO-3016
- PCS <275 psia (260 psig) allows openning
Procedural pressure limit is <265 psia to enable MO‑3015 and 3016 to be opened.
What is the basis for the procedural limitations / interlocks on opening MO-3015/3016?
Set to not violate the equipment limitations.
- 265 psia maintains the plant pressure less than the LTOP pretrip alarm setpoint.
- Pretrip alarm setpoint was established to prevent exceeding 270 psia.
- 270 psia setpoint is based on the limitation of the shutdown cooling piping.
- Instrumentation inaccuracies and corrections for pressure due to instrumentation location reduce the 300 psia value to 270 psia.
What is required on SDC to protect agains over pressure?
- LTOP System is operable with channels in SDC position.
- PCS is vented via a vent path capable of relieving 167 gpm at a PCS pressure of 315 psia.
With the PCS pressurized, what limitations are on MO-3015/3016 operating ability if already open?
When the PCS is pressurized AND MO-3015 and MO‑3016 are OPEN, THEN power shall be maintained to at least one of the two valves. This prevents an unisolable PCS leak if RV-3164 fails open.
What is purpose, setpoint and relief path of RV-0401?
- Protects piping between MO-3015 & 3016
Setpoint: 2485 psig
Relieves to the PSDT, T-74
What is purpose, setpoint and relief path of RV-0402/0403?
RV‑0402 and RV‑0403
- Setpoint: 500 psi
- Protect the SDC Hxs (tube side) and piping from pressure developed due to an increase in ambient temperature in safeguards room.
- Relieve to the Engineered Safeguards Sump.
What is purpose, setpoint and relief path of RV-03164, SDC Suction Relief?
RV-3164 SDC Suction Relief
- Setpoint: 300 psig
- Overpressure protection for SDC suction piping. Postulated event is intermediate letdown pressure controller failure/misoperation while in solid plant pressure control with SDC in operation.
- Relieves to the Quench Tank, T-73
What are the LPSI Pumps Inlets from SIRWT Valves?
- MO-3189 (P-67B suction) from SIRWT
- MO-3198 (P-67A suction) from SIRWT
What are the LPSI Pumps Inlets from SDC Valves?
MO-3190 (P-67B suction from PCS)
MO-3199 (P-67A suction from PCS)
What are the LPSI pump specs?
Single Stage, Horizontal, Centrifugal
o Maximum Flow - 4,500 gpm
o Minimum Flow - 163 gpm
· Design Head - 350 ft
o Shutoff Head - 410 ft
· Horsepower - 400
· Seals - Mechanical
· NPSH Required at 3,000 gpm - 11 ft
Maximum Normal Suction Pressure - 270 psia