Primary Vent System Flashcards
What is purpose of the Primary Coolant Gas Vent System?
Designed to vent steam or noncondensible gases from the Reactor Vessel head and Pressurizer under post accident conditions.
May also be used to aid in the pre- or post-refueling venting of the PCS. Vent flow is directed to the Primary System Drain Tank or Waste Gas System via the Quench Tank to prevent inadvertent release of radioactive fluid to Containment.
PRV-1067, PRV-1068 Reactor Head Vent Valves power supplies and design.
PRV-1067, Reactor Head Vent Valve
- D-11-1
PRV-1068, Reactor Head Vent Valve
- D-21-1
Solenoid pilot operated valves.
- One inch diameter
- Rated for 2500 psia
- 650°F.
The valves are in parallel and are powered from separate DC Buses.
PRV-1069 and PRV-1070, Pressurizer Vent Valves power supplies and design.
PRV-1069, Pressurizer Vent Valve
- D-11-1
PRV-1070, Pressurizer Vent Valve
- D-21-1
Solenoid pilot operated valves.
- One inch diameter
- Rated for 2500 psia
- 650°F.
- The valves are in parallel and are powered from separate DC Buses.
What are RO-0101, Reactor Head Restricting Orifice and RO-0102, Pressurizer Restricting Orifice?
Reactor Head and Pressurizer Restricting Orifice
- 1” size, rated at 2500 psig.
- It is placed as close to the Reactor Vessel or Pressurizer as possible to limit the possibility of an uncontrolled Loss of Coolant Accident.
- Sized to limit mass loss from a line break to less than the makeup capability of a single charging pump.
Describe PRV-1071, PCS Vent to Containment
PRV-1071, PCS Vent to Containment
- Powered from D11-1
Solenoid pilot operated valve
- One inch nominal diameter
- Rating of 2500 psia and 650°F.
- Discharges to the open area of Containment above the Pressurizer Shed where adequate mixing with the Containment atmosphere is assured. .
Describe PRV-1072, PCS Vent to the Quench Tank
PRV-1072, PCS Vent to the Quench Tank
- Powered from D21-1
Solenoid pilot operated valve
- One inch nominal diameter
- Rating of 2500 psia and 650°F.
- Discharges to the common header which routes the discharges from the PZR Code Safety Valves and the PORVs to the Quench Tank.
Draw the Primary Vent System
Per Attachment 2 of Lesson Plan
EOP Supplement 26 Section 3.0, “Non-Condensible Void Removal, Reactor Vessel Head.”
- Venting through PRV‑1072 to the Quench Tank (preferred)
- Or through PRV-1071 to Containment
Reactor Void Removal
- PRV-1067 or PRV-1068 is opened to start the vent
Pressurizer Void Removal
- PRV-1069 or PRV-1070 is opened to start the vent
After depressurization, how is first drain vented?
The first drain after depressurization both the Pressurizer and the Reactor Head are vented via MV-PC1044A and MV-PC1044B.
What are the control room valve controls and indication.
There are six valve control circuits, one for each valve.
- PRV-1067/1068 Reactor Vent Valves
- PRV-1069/1070 Pressurizer Vent Valves
- PRV-1071, PCS Vent to Containment
- PRV-1072, PCS Vent to Quench Tank
Each valve is controlled by a keyswitch with an “OPEN”, “CLOSE”, and “RESET” position each with an open and closed indication.
Loss of power, KS must be taken to Close. This feature ensures the PRV’s do not re‑open on a loss of power and subsequent re‑energization.
What alarms?
No Alarms
What are control room indications of PVS?
Valve positions
The Gas Vent Header pressure of the common discharge line is indicated in the Control Room on PIA-1066.
How does the Primary Vent System interact with H2 Monitoring?
System is designed to vent gases into Containment, the EOPs direct a hydrogen monitor be in operation to detect for excessive hydrogen concentration.
How does the Primary Vent System interact with Containment Cooling?
Containment Air Cooler fans (V-1A/B, 2A/B, 3A/B, 4A/B) ensure mixing of containment atmosphere for representative sampling.
How does the Primary Vent System interact Station Power?
Odd numbered (PRV-1067, PRV-1069 and PRV-1071)
- Powered from D11-1.
Even numbered (PRV-1068, PRV-1070 and PRV-1072)
- Powered from D21-1.
PIA-1066 is powered from L-08 Breaker 1 via Bus 1C/LCC-13/MCC-3
