Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
19 Cards in this Set
- Front
- Back
|
Direct steam from the reactor through the primary containment to the Main Turbine and various
steam loads. Isolate the reactor during abnormal operating conditions. Depressurize the reactor upon given conditions. |
Main Steam System
|
|
|
Describe the Main Steam Line flowpath, sequentially listing the line penetrations and/or
components of the system |
RCIC Steam supply and the reactor head vent tap off Main Steam Line “A”
Flow Elbows Safety Relief Valves Flow Restrictors Inboard Main Steam Isolation Valves Guard Pipes Outboard Main Steam Isolation Valves Main Steam Shutoff Valves Steam Line Drain Tapoffs Pressure Equalizing Header Averaging Manifold |
|
|
Protect the reactor vessel from an overpressure condition by opening automatically upon
a high pressure condition. Depressurize the reactor during a LOCA situation to allow low pressure ECCS pumps to inject water into the reactor. |
SRVs
|
|
|
surround the Main Steam piping between the Drywell and shield
building walls. They are closed on the shield building end and open on the Drywell end. If a Main Steam line ruptures somewhere between the Drywell and shield building, the steam will be directed back to the Drywell. This prevents a pressurization of the Containment and Annulus regions of the reactor building in the event of a Main Steam line break. |
Main Steam guard pipes
|
|
|
Used to protect the reactor from an overpressure condition. The
SRVs are air-operated in this mode. They begin to open at 1133 psig reactor pressure. |
Relief Mode (16 SRVs used)
|
|
|
Used to protect the reactor from an overpressure condition if the
SRVs in the relief mode allow reactor pressure to rise above the relief setpoints. System pressure opens the SRVs in this mode. They begin to open at 1195 psig reactor pressure. |
Safety Mode (16 SRVs used)
|
|
|
This mode reduces the relief setpoints of 5 SRVs after 1133
psig reactor pressure is reached. When this happens, the 5 SRVs will cycle open and close at reactor pressures lower than 1133 psig. The SRVs are air-operated in this mode. The purpose of this mode is to reduce cyclic pressure stresses on the containment |
Low Low Set Mode (5 SRVs used)
|
|
|
This mode is used to completely depressurize the reactor vessel
during a LOCA when reactor pressure is too high to allow the injection of low pressure ECCS pumps. The SRVs are air-operated in this mode. |
ADS Mode (7 SRVs used)
|
|
|
The MSIVs are 24”, air-opened, ____-closed, angle globe valves. Air is supplied from
the____. |
spring and air / Instrument Air System
|
|
|
The MSIVs will close automatically upon the following conditions:
|
Reactor water level - Level 1 (-143”)
Main Steam line high flow Main Steam line low pressure Low Main Condenser Vacuum Main Steam Tunnel high ambient temperatures |
|
|
The MSIVs will go closed in____
|
3 to 5 seconds.
|
|
|
The____ minimum closing time is based on minimizing valve damage and reactor pressure
surges following an MSIV closure. |
3 second
|
|
|
The _____ maximum closing time is based on keeping the core covered following a Main
Steam line rupture and to contain fission products following fuel damage. |
5 second
|
|
|
If the Instrument Air header drops to approximately ___, the MSIVs will go closed. There are
air accumulators associated with the MSIVs, but they are only used to assist in____? |
50 psig / closing the valves,
not holding them open. |
|
|
The MSIVs are ____. To seal them against leakage, air is injected into the volume between the inboard and outboard MSIVs. The outboard MSIV stem seals are also pressurized by ___.
|
angle globe valves / MS-PLCS
|
|
|
____ provide pressurized sealing air to containment isolation valves to prevent the unfiltered release of fission products to the environment after a LOCA.
|
PVLCS and MS-PLCS
|
|
|
The _____ also serve as a backup source of air for the Main Steam SRV air system
|
PVLCS air compressors
|
|
|
PVLCS air compressors are initiated ____ after a LOCA. (PVLCS injection valves won’t open until process line pressure is less than 35 psig).
|
manually 20 minutes
|
|
|
MS-PLCS is initiated ____ after reactor pressure is below ___ psig and air accumulator pressure is greater than ___ psig.
|
manually / 25 /45
|
