Lgs Ilt - Primary & Secondary Containment

Front 1

State the purposes of the Primary Containment.

Back 1

- Contain and suppress the steam and steam pressure resulting from a LOCA.
- Limit release of fission products to the Reactor Enclosure.
- House and support reactor vessel and support equipment

Front 2

component function:
a. Biological Shield

Back 2

- Surrounds reactor vessel, reducing gamma and neutron radiation in order to:
- Facilitate drywell access
- Minimize activation of drywell components
- Minimize degradation of organic compounds.

Front 3

component function:
b. Drywell Head

Back 3

- Top of the drywell and is removable for access to vessel

Front 4

component function:
c. Steel Liner

Back 4

- 0.25" carbon steel liner. Anchored to containment wall. Acts as leak tight membrane

Front 5

component function:
d. Suppression Chamber Water Volume

Back 5

- Provides for the condensing of gases released during LOCA in order to reduce pressure inside containment

Front 6

component function:
e. Downcomers

Back 6

- 87 downcomers provide a flow path for uncondensed steam between drywell and suppression chamber water volume.

Front 7

component function:
f. Vacuum Breakers

Back 7

- Provides a flow path to return non-condensables to drywell. Limits upward force on drywell floor to 3 psig, to prevent downcomer and Drywell collapse on negative pressure in drywell compared to pool air chamber

Front 8

component function:
g. Suppression Pool Cleanup Pumps

Back 8

- Designed to maintain pool clarity, the cleanup pump takes suction on pool through two series MOV's that isolate on Group VIIIB (-38", 1.68#) signal
- Sends water to condenser hotwell via FV-C-*29, with water returned to pool from condensate transfer system via FV-C-*30. Each flow control valve is manually set to maintain the pool level during the cleanup process.
- Water returns via core spray Loop "A" min flow line, with normal flow approximately 450 gpm to 550 gpm

Front 9

design values for Drywell Internal Pressure

Back 9

55 psig

Front 10

design values for Drywell External Pressure

Back 10

5 psig

Front 11

design values for Drywell Temperature

Back 11

340ºF

Front 12

design values for Drywell Floor Differential Pressure (Upward and Downward)

Back 12

20 psi / 30 psi

Front 13

design values for Suppression Chamber Internal and External Pressure

Back 13

55 psig / 5 psig

Front 14

design values for Suppression Chamber Temperature

Back 14

220ºF

Front 15

a. RHR
operational support for the Primary Containment and discuss the effects on the Primary Containment to a loss or malfunction of each

Back 15

- RHR is used in its various modes for suppression pool cooling/spray, drywell spray and cooling water for H2 recombiners

Front 16

b. Main Condenser
operational support for the Primary Containment and discuss the effects on the Primary Containment to a loss or malfunction of each

Back 16

- Suppression Pool cleanup system discharges to the main condenser when cleaning up suppression pool water

Front 17

c. Condensate Storage and Transfer
operational support for the Primary Containment and discuss the effects on the Primary Containment to a loss or malfunction of each

Back 17

- The CST is the source of makeup water to the suppression pool utilizing the condensate transfer pumps

Front 18

d. Drywell Ventilation
operational support for the Primary Containment and discuss the effects on the Primary Containment to a loss or malfunction of each

Back 18

- Eight unit coolers remove heat from drywell during normal operation. One fan of each cooler operated to circulate air cooled by the Drywell Chilled Water System.

Front 19

e. Drywell Chilled Water
operational support for the Primary Containment and discuss the effects on the Primary Containment to a loss or malfunction of each

Back 19

- Provides cooling water to the eight unit coolers.

Front 20

f. AC Electrical Distribution
operational support for the Primary Containment and discuss the effects on the Primary Containment to a loss or malfunction of each

Back 20

- AC Power is required for DWCW Pumps and Chillers, DW Cooler Fans, and valve and pump operations required for Suppression Pool Cooling, Drywell Spray, Suppression Pool Spray, H2/O2 Sampling, and Suppression Pool Cleanup Pump operation. NSSSS valves can fail closed on a loss of AC logic, or can remain open on a loss of AC to the valve’s motor operator.

Front 21

g. D.C. Electrical Distribution
operational support for the Primary Containment and discuss the effects on the Primary Containment to a loss or malfunction of each

Back 21

- DC power is required to operate RHR pump breakers and DWCW chiller breakers (4 kV breakers). A loss of DC may result in increasing drywell temperature and pressure upon the loss of the chillers and prevent the operation of Drywell Spray, Suppression Pool Spray, and Suppression Pool Cooling.

Front 22

h. Containment Atmosphere Control
operational support for the Primary Containment and discuss the effects on the Primary Containment to a loss or malfunction of each

Back 22

- Monitors containment H2/O2 concentrations
- Provides a means to inert/de-inert the primary containment with nitrogen.

Front 23

normal values at 100%power
a. Suppression Pool Level

Back 23

Normal Full Power Value 23.5’

Front 24

normal values at 100%power
b. Drywell Pressure

Back 24

Normal Full Power Value 0.3 psig

Front 25

normal values at 100%power
c. Drywell Temperature

Back 25

Normal full power value 130°F

Front 26

normal values at 100%power
d.          Drywell to Suppression Pool D/P

Back 26

Normal full power value 0 psig; therefore, normal D/P is 0.3 psid

Front 27

Summarize suppression chamber operations following a LOCA.

Back 27

- During LOCA, steam and water will enter the drywell atmosphere. The subsequent rise in drywell pressure will force the mixture into the suppression pool via the downcomers.
- Steam condensation will take place in the suppression pool while non-condensables will rise out of the pool and into the suppression chamber air volume.
- Major portion of non-condensables from Nitrogen atmosphere in drywell being forced into suppression pool.
- Following the LOCA, heat losses in the drywell will cause drywell pressure to decrease. To prevent drawing the drywell pressure negative, vacuum breakers have been installed between the drywell and the suppression chamber air volume.
- Heat losses due to ambient heat losses, drywell sprays, drywell chillers
- Vacuum breakers installed on downcomers
- At .5 psid across the vacuum breaker (suppression chamber greater than drywell atmosphere), the vacuum breakers will open and allow the non-condensibles in the suppression chamber air volume to be released back into the drywell.
- Important reason for maintaining suppression pool level since covering the vacuum breakers will prevent the release of non-condensables back into the drywell.

Front 28

Identify how the following supports the Secondary Containment:
a. SGTS

Back 28

- A loss of RE ventilation will cause a rise in RE pressure. After a time delay, SGTS will start and restore the negative P.
- SGTS maintains designed negative pressure
- SGTS will achieve and maintain .25” wg vacuum within 916 seconds.

Front 29

Identify how the following supports the Secondary Containment:
b. Reactor Enclosure Ventilation System

Back 29

- Reactor enclosure and refuel floor ventilation system fans maintain the slight vacuum
(-0.25"wg) in the secondary containment. A loss of RE ventilation will cause a rise in RE pressure. After a time delay, SGTS will start and restore the negative P.
- Following LOCA signal:
- RE Ventilation is isolated
- SGTS and RERS automatically start

Front 30

Identify how the following supports the Secondary Containment:
c. Primary Containment System

Back 30

- The secondary containment functions as the primary containment during refuel operations when a unit's primary containment is open.

Front 31

Identify how the following supports the Secondary Containment:
e. Exhaust Stack

Back 31

- One outboard MSIV room blowout panel relieves directly to the reactor building roof via a vent stack next to the North Stack.

Front 32

Identify how the following supports the Secondary Containment:
f. Blowout Panels

Back 32

- Blowout panels are mounted in the following locations:
- Outboard MSIV Room
- One panel relieves at .5 psid directly to the reactor bldg .roof via a vent stack
- One panel relieves at .5 psid from the North wall into the turbine enclosure.
- RWCU Room
- One .5 psid blow out panel on the west side of the reactor enclosure Unit #1 (East side Unit #2)
- HPCI and RCIC Rooms
- Each room vents to the isolation valve compartment through .1 psid upward acting blowout floor panels into the isolation valve compartment, with a 0.5 psid blowout panel venting the valve compartment to the south side of the reactor bldg.
- The four paths described are unmonitored release paths to the environment. Each system discussed has NS4 isolations. The inability to manually isolate systems would lead to plant S/D and depressurization IAW T-103

Front 33

Identify the effect of a loss or malfunction of the secondary containment on off-site radioactive release rates.

Back 33

- If blowout panels open to relieve pressure, they are unmonitored and unfiltered release paths to the environment.