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Secondary Containment Systemy
304B Chapter 4.2
Objectives
1. Identify the system's purposes.
2. Explain the function and operation of the following secondary containment features:
a. Reactor buildingg
b. Relief panels
c. Airlocks
d. Reactor building normal ventilation system isolation valves and dampers
e. Unit area coolers
f. Primary containment purge system
Objectives
3. List the conditions that will isolate the reactor building normal ventilation system (RBNVS).
4. Explain the following flow paths:p g pa. Air transfer through the RBNVSb. Purge vent & exhaust from primary containment
5. Define secondary containment integrity.
Objectives
6. Summarize the response of secondary containment equipment response to accident conditions.
7. Describe how secondary containment yinterrelates to the following:
a. Primary Containment Systemb. Reactor Building Standby Ventilation
Systemc. Nuclear Steam Supply Shutoff System
Cab
Polar Crane
PrimaryC t i t
SecondaryContainment
New FuelVault
FuelPool
Ele. 175'
Ele 150'
ElevatorShaft
•Reactor building
•Relief panels
•Air locks
•Reactor building normal ventilation system (RBNVS)
ShieldWall
RX
AccessLock
EquipmentRoom
Containment
VerticalVent
Platform
PressureSuppression
Chamber
SuppressionPool
Ele. 150
Ele. 115'
Ele. 40'
Ele. 20'
Ele. 00'
Figure 4.2-1 Mark II Containment
system (RBNVS)
•Primary containment purge system (PCPS)
Purpose
• The purposes of the Secondary Containment System are:– minimize the ground level release of
radioactive material following an accidentradioactive material following an accident
– to provide primary containment when the drywell or suppression chamber are open.
Reactor Building
• Concrete
• Blowout panels
• Encloses primary containment
• Serves as primary containment when drywell or suppression chamber are open
Relief panels
• turbine building blowout panels
• main steam tunnel relief vents
• the reactor building exterior metal siding.
Airlocks
Entry to and exit from the reactor building are through double door personnel and equipment air locks. Each pair of access doors is equipped with rubber weather-stripdoors is equipped with rubber weather strip type seals. The doors are electrically interlocked so that only one of the pair may be opened at a time.
º
º
º
º
º
º
º
º
8' Ele.
40' Ele.
63' Ele.
76' Ele.
95' Ele.
113' Ele.
150' Ele.
º
º
º
º
º
º
º
RefuelingFloor
10 Sec. TD.
º40A
40B
41B
41A
Plenum
HeatingCoil
TIC
TIC
CoolingCoils
TIC
TCV
TCV
To DrywellPurge System
PleatedFilter
PDI GlycolHeater
Fan 3A
Fan 3B
Fan 3C
36A
36B
36C
Reactor BuildingExhaust Fans
37A 37B
Station VentilationBooster Exhaust
Fans (Typical of 3)
Station VentilationExhaust Stack
31A 31B
To RBSVSMixing Plenum
35A
35B
PCD11A
PCD11B
NCNC
Reactor BuildingSupply Fans
RE
RE
SecondaryContainment
Containment Purge (Exhaust)
Containment Vent (Exhaust)
PDC
11
ForRBSVS
43B
PDIC
43A
PDIC
RWCU Pump Area
EL. 112'EL. 78'
CRD Repairand Storage
EL 128'
RWCU ValveChamber
Phase Sep. Tk.Contam. Stor.
EL 150'S EL 128'
RWCU Ht.Exchanger
Fuel PoolCooling
EL 150'N
UC-18
UC-16AUC-16B
FNS - 30A & B
Reactor BuildingSteam Pipe Tunnel
EL. 78'
Figure 4.2.2 Reactor Building Normal Ventilation System
RBNVS
The RBNVS consists of:• heating and air conditioning supply units with
two supply fans• three exhaust fans• distribution ducts• manually positioned ventilation louvers• differential pressure controlled dampers• unit coolers• controls and instrumentation.
Sub-Atmospheric Pressure
• - 1.5 inch ΔP
• Prevents out-leakage
• Pressure control dampers
RBNVS Supply Flow
• Intake louver
• Supply fans
• Pressure Control Dampers
• Heaters & coolers
• Distribution ducts
RBNVS Exhaust Flow
• Exhaust plenum
• Refuel area
• Exhaust fans
• Station ventilation exhaust duct
Area Unit Coolers
• Local
• Some are safety-related
• Auto-initiation
• RBSVS/Control Room Air Conditioning Chilled Water System cooling water
Primary Containment Purge
• Primary Containment Purge System (PCPS)– a high efficiency particulate absolute (HEPA)
filterfilter
– a charcoal adsorber
– a fan
• De-inerts primary containment to allow normal personnel access
Secondary Containment Integrity
• The operational conditions that require that secondary containment integrity must be maintained include:
• all times that primary containment integrity is required (i.e.; the reactor is critical or moderator (temperature is >212F and fuel is in the reactor vessel)
• when fuel handling operations are in progress within the secondary containment
• when activities are being performed that have a potential for draining the reactor vessel.
Secondary Containment Integrity
• reactor building is intact• RBNVS automatic isolation valves are operable or
deactivated in the closed position.• RBSVS is operable.• Secondary containment pressure is less than or equal to
1 5 inch H2O gauge-1.5 inch H2O gauge.• Secondary containment leakage rates are within
specified limits.• All containment penetration seal mechanisms are
operable.• At least one door in each access opening is closed.• All equipment hatches are closed and sealed.
Operations
• Normal
• Infrequent
• System Isolation
Isolation Signals
• High drywell pressure high (>1.69 psig)• Reactor vessel low low level (Level 2, -38
inches)• Refuel area exhaust ventilation radiationRefuel area exhaust ventilation radiation
high (>35 mR/hr)• Vent/purge exhaust ventilation radiation
high (>5.4 x 105 cpm)• Reactor Building low ΔP (> -0.30" H2O)• RBSVS initiation signal, multiple inputs.
System Interfaces
• Primary Containment System (Chapter 4.1)
• Reactor Building Standby Ventilation System (Chapter 4 3)System (Chapter 4.3)
• Nuclear Steam Supply Shutoff System (Chapter 4.4)
• Emergency AC Power (Chapter 9.2)
Cab
Polar Crane
PrimaryC t i t
SecondaryContainment
New FuelVault
FuelPool
Ele. 175'
Ele 150'
ElevatorShaft
REVIEW
•Relief panels
•Air locks
•Reactor building ShieldWall
RX
AccessLock
EquipmentRoom
Containment
VerticalVent
Platform
PressureSuppression
Chamber
SuppressionPool
Ele. 150
Ele. 115'
Ele. 40'
Ele. 20'
Ele. 00'
Figure 4.2-1 Mark II Containment
normal ventilation system (RBNVS)
•Primary containment purge system (PCPS)
º
º
º
º
º
º
º
8' Ele.
40' Ele.
63' Ele.
76' Ele.
95' Ele.
113' Ele
º
º
º
º
º
º
RefuelingFloor
10 Sec. TD.
º40A
40B
41B
Plenum
HeatingCoil
TIC
TIC
CoolingCoils
TIC
TCV
TCV
To DrywellPurge System
PleatedFilter
PDI GlycolHeater
Fan 3A
Fan 3B
Fan 3C
36A
36B
36C
Reactor BuildingExhaust Fans
Station VentilationBooster Exhaust
Fans (Typical of 3)
Station VentilationExhaust Stack
31A 31B
To RBSVSMixing Plenum
35A
35B
PCD11A
PCD11B
NCNC
Reactor BuildingSupply Fans
RE
RE
REVIEW
º
113 Ele.
150' Ele. º41A
37A 37B
SecondaryContainment
Containment Purge (Exhaust)
Containment Vent (Exhaust)
PDC
11
ForRBSVS
43B
PDIC
43A
PDIC
RWCU Pump Area
EL. 112'EL. 78'
CRD Repairand Storage
EL 128'
RWCU ValveChamber
Phase Sep. Tk.Contam. Stor.
EL 150'S EL 128'
RWCU Ht.Exchanger
Fuel PoolCooling
EL 150'N
UC-18
UC-16AUC-16B
FNS - 30A & B
Reactor BuildingSteam Pipe Tunnel
EL. 78'
Figure 4.2.2 Reactor Building Normal Ventilation System
Objectives
1. Identify the system's purposes.
2. Explain the function and operation of the following secondary containment features:
a. Reactor buildingg
b. Relief panels
c. Airlocks
d. Reactor building normal ventilation system isolation valves and dampers
e. Unit area coolers
f. Primary containment purge system
Objectives
3. List the conditions that will isolate the reactor building normal ventilation system (RBNVS).
4. Explain the following flow paths:p g pa. Air transfer through the RBNVSb. Purge vent & exhaust from primary containment
5. Explain what constitutes the secondary containment barriers.
6. Define secondary containment integrity.
Objectives
7. Summarize the response of secondary containment equipment response to accident conditions.
8. Describe how secondary containment yinterrelates to the following:
a. Primary Containment Systemb. Reactor Building Standby Ventilation
Systemc. Nuclear Steam Supply Shutoff System
Are there any questions?
