1. Provide barrier which controls the release of fission products to secondary contaiment in the event of a LOCA
2. Rapidly reduce the pressure in the contaiment resulting from a LOCA.

1. Maintains drywell atmaosphere below 135 degrees F bulk avg temperture
2. Reduces temperature to 105 degrees in 8-10 hours after shutdown

Limits the negative pressure in either the torus or drywell to less than (external) design pressure of -2 psig

68,000 ft³

(corresponds to -3.3 inches of level)

108,250 ft³

(corresponds to +2.2 inches)

Normal operating range for torus water temperature

18 inch check valve designed to be full open at 0.5 psid.

Air operator provided for testing purposes

Unsleeved penetrations: process flow in contact with original penetration.

Sleeved: process flow is not in contact with penetrating pipe.

• HOT sleeved: those which accommodate thermal expansion
• COLD sleeved: those which experience relatively little thermal expansion.

Guard pipe between hot line and penetration nozzle, in addition to double seal arrangement. Bellows accomodates relative movement between hot line and containment shell.

To maintain drywell atmosphere less than 135 degrees F during normal operation. Also, to reduce the air temperature to 105 degrees F in 8 - 10 hours after shutdown.

Normal ops with three fans running. Each mode has a different fan in standby.

NOTE: Mode 1 has fan #1 in stby, Mode 2 has #2 fan in stby etc."

1. Prevents primary containment from exceeding external design pressure;
2. Provides a means of eliminating pressure fluctuations caused by termperature changes during various modes of operation;
3. Provides a means for purging and venting primary containment;
4. Establishes an inert atmosphere, with means for sampling primary containment atmosphere.

1. Purge: liquid N₂ through purge vaporizer (steam) to containment (high Volume)
2. Makeup: liquid N₂ through atmospheric vaporizer to containment.

• less than or equal to 90 degrees F at power levels above 1% and no testing that adds heat to the torus;
• less than or eqal to 100 degrees F at power levels above 1% and testing that adds heat to the torus;
• less than or equal to 110 degrees F at power levels less than 1%.

Greater than or equal to -4.0 inches and less than or equal to +3.0 inches.

Operating limits are between -3.3 inches and +2.2 inches

MSIVs trip on:

1. Less than 840 psig with mode switch in RUN;
2. Rx Low-Low Level (-47 inches);
3. High Area Temp (195-200 degrees F)
4. 135-140% steam flow.

PCT trips on

1. Rx Low Level (+9 inches) or
2. High Drywell Pressure (1.84 psig)

Non-liquid PCT trips on

1. Fuel pool high rad (50 mR/hr) or 
2. Rx Building Plenum High rad (26 mR/hr)

NOTE: these trips are NOT 1-out-of-2 taken twice.

RWCU trips on

1. Low-low level (-47 inches);
2. High drywell Pressure 1.84 psig;
3. High Flow (462 gpm for 10 seconds);
4. Low Flow (-200 gpm for 10 seconds);
5. RWCU room high temperature (170 degrees F).

RCIC trips on

1. High steam flow (44,434 lbm per hour for 5 seconds);
2. RCIC steam line area high temp (187.5 degrees F);
3. RCIC steam line low pressure (60 psig)

HPCI trips on

1. HPCI high steam flow (300,000 lbm per hour for 4 seconds);
2. HPCI steam line area temperature (187.5 degrees F);
3. HPCI steam supply line low pressure (100 psig)

1. Initiation signal must be clear;
2. All MSIV handswitches are placed in CLOSE
3. Reset pushbutton.

1. Initiation signal must be clear;
2. All handswitches in the group are placed in CLOSE with exception of MOVs;
3. Reset pushbuttons.

1. Initiating signals clear;
2. Reset Pushbuttons.

0 to 80 psig (C-04)

and

-5 to +250 psig (C-03)

-15 to +15 inches with 0 inches at 910 foot elevation.

Additional wide range instrument measures -8 feet to +15 feet with same zero elevation.

Limit the open position of the vavle disc to less than or equal to 40 degrees from full closed.

This limits the stress in the valve shaft caused by the dynamic torque developed by the flow of air across the valve disc due to a DBA-LOCA pressure in the containment.

1.75 psig or 40 degrees F.

Ops manual general precaution says normally, temperature is maintained around 100 degrees F and purge SHALL be stopped if temperature falls below 60 degrees F.

Set to rupture between 44 and 50 psig.

Can be manually burst from ASDS Panel using keylocked switch. This will take approximately 5 minutes at ambient temperature and uses Nitrogen.