General Flashcards by Scott Williams

What is the purpose of the Control Rod Drive Hydraulic System?

1) Provide high pressure water to the Control Rod Drive Mechanism for inserting, withdrawing, scramming, and cooling.
2) Provide water to flush the Reactor Recirculation Pump Seals, provide makeup to the Reactor, provide a sample connection, and RPV Level Instrument reference leg purge.

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What are the suction sources for the Control Rod Drive pumps?

1) The normal supply is from the Condensate System downstream of the Demineralizer outlet, at the suction of the Condensate Booster Pumps.
2) The Condensate Storage Tank provides an alternate source via a check valve.

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How many suction filters are provided for the Control Rod Drive pumps, and where are they located?

There are two suction filters, one is normally in service. The Suction Filters are located at IB-574.

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What are the power supplies to the Control Rod Drive Pumps, and where are the pumps located?

A - XH11
B - XH12

The pumps are located at IB-574

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How many stages do the Control Rod Drive Pumps have?

The CRD Pumps are 9 stage centrifugal pumps.

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How many lube oil pumps does a Control Rod Drive Pump have?

The Control Rod Drive Pumps has an Auxiliary Lube Pump and an Attached Lube Oil Pump.

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When is the Auxiliary Lube Oil Pump utilized?

The Auxiliary Lube Oil Pump is used during startup and when the Attached Lube Oil Pump is degraded or fails.

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What is the start permissive for the Control Rod Drive Pump Auxiliary Lube Oil Pump?

Control Switch taken to START and lube oil pressure less than 9 psig.

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When will the Control Rod Drive Auxiliary Lube Oil Pump auto start and stop?

The Auxiliary Lube Oil Pump will automatically start at less than 5 psig lube oil pressure with the respective pump breaker closed. The Auxiliary Lube Oil Pump will shutdown to standby when oil pressure is greater than or equal to 9 psig.

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What is the power supply to the Control Rod Drive Auxiliary Lube Oil Pumps?

A - F1C08

B - F1D08

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What system provides the cooling water for the Control Rod Drive Pump Lube Oil?

Nuclear Closed Cooling

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What is the flow rate through the minimum flow line, and where does it return water?

20 gpm is returned to the CST through the minimum flow line.

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What are the Control Rod Drive Pump start permissives?

1) Drive pump suction pressure greater than 25” HgA

2) Pump oil pressure not low - Blue Light ON

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What are the Control Rod Drive Pump automatic trips?

1) Low suction pressure less than 25.8” HgA
2) Low oil pressure less than 3 psig
3) Undervoltage - will NOT restart when power is restored
4) Overcurrent

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How many Drive Water Filters are there, and where are they located?

There are two Drive Water Filters located at IB-574, normally one is in service.

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What signals will cause the Control Rod Drive Hydraulic Outboard Containment Isolation Valve to automatically close?

NONE!! There are no automatic isolation signals.

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What is unique about the Control Rod Drive Flow Control Valve when it’s fully closed or fails closed?

The Flow Control Valve will still pass 5 gpm in the full closed position.

What is the purpose of the Control Rod Drive Pressure Control Valve?

The Pressure Control Valve is a motor operated throttle valve that is set to maintain CRD pressure 250#-275# above Reactor pressure.

What are the three components that work together to maintain Control Rod Drive Hydraulic pressure?

1) Pressure Control Valve
2) Stabilizing Valves
3) In-line Relief Valve

What is the purpose of the Stabilizing Valves, how many are there, and how do they fail?

The Stabilizing Valves close to divert water to the drive header for rod movement and to maintain CRD pressure.

There are a total of 8 Stabilizing Valves in 4 pairs.

The Stabilizing Valves are solenoid operated valves that fail closed on a loss of power to ensure rod motion is possible.

How many gallons per minute does each Stabilizing Valve pass, and how many close for each Control Rod manipulation?

Each Stabilizing Valve passes 2 gallons per minute.

1 Stabilizing Valve closes for a rod withdrawal, and 2 Stabilizing Valves close for a rod insertion.

What is the purpose of the Control Rod Drive In-Line Relief Valve?

The In-Line Relief:

1) Prevents over-pressurizing the Drive Water header.
2) Prevents excessive rod speeds if the Stabilizing Valves failed closed.

What is the purpose of the Control Rod Drive Pressure Equalizing Valves?

The Pressure Equalizing Valves connect the the Cooling Water Header and the Exhaust Header.

The Pressure Equalizing Valves will pressurize the Exhaust Header if an excessive differential pressure exists, such as after a scram, to prevent excessive rod speeds.

What are the setpoints for the Pressure Equalizing Valves?

75 psid and 85 psid

What are all the risers connect to the Control Rod Drive Hydraulic Control Units?

1) Insert 2) Charging 3) Exhaust 4) Scram Discharge 5) Drive 6) Cooling 7) Withdrawal

What is the purpose of the Directional Control Valves?

The Directional Control Valves receive alignment signals from the Rod Control and Information system to allow movement of the Control Rods.

What is the purpose of the Ball Check Valve?

The Ball Check Valve ensures that the Control Rod can be scrammed when Reactor pressure is greater than 600 psig. If for any reason the Charging Water Header pressure is less than Reactor Pressure this Ball Check Valve will unseat and push the rod in if the Scram Valves have opened.

What is the rate of water than can be added to the Reactor as makeup if needed?

The makeup rates are: 1) 180 gpm for one CRDH Pump 2) 216 gpm for two CRDH Pumps The Scram Inlet Valve must be open for this flow path that allows water to makeup to the Reactor from the Charging and Cooling Water headers.

How is a constant differential pressure maintained in the Control Rod Drive Hydraulic System during a plant startup?

The Pressure Control Valve is adjust to a set position to maintain 250#-275#. The Flow Control Valve, which is set at 60 gpm, opens as Reactor pressure increase to increase the flow and maintain the desired differential pressure.

What system provides the air for the Control Rod Drive Flow Control Valve?

Instrument Air

What happens to the Control Rod Drive Flow Control Valve following a Scram?

When the Scram Valves open on all 177 Hydraulic Control Units a flow path is opened for makeup to the Reactor Vessel through the Control Rod Drive Mechanisms. The Control Rod Drive Hydraulic Pumps will operate at close to run out as flow increases to full scale for Total System Flow. The Flow Element, upstream of the Charging Header, detects this increase in flow and fully closes the Flow Control Valve because flow will remain high. The flow remains high even though the Flow Control Valve attempts to lower flow because the Flow Control Valve is located downstream of the Charging Header.

When a Control Rod is moved where does the water than enters the Exhaust header go?

The water that enters the Exhaust Header from the movement of a Control Rod flows through to the other latched Control Rods through their 121 Directional Control Valves. This valve will open on a differential pressure of 3 psid porting the water to the over-piston volume.

What is the purpose of the Scram Discharge Volume?

The Scram Discharge Volume receives the water displaced from to the top of 177 CRDM Pistons during a scram.

What are the important levels in the Scram Discharge Volume, and what actions occur based on the levels?

5 gallons - not drained alarm 12 gallons - Rod Block 24 gallons - Scram

What are the Control Rod blades made out of?

The Control Rods used to be strictly tubes filled with Boron powder, and the newer blades are made of Boron powder filled tubes and Hafnium.

What is the purpose of the Control Rod Drive Mechanisms?

The Control Rod Mechanisms position the Control Rods in the Core at notch(6 inch) intervals.

How is Control Rod position determined?

The Control Rod Mechanism has an attached index tube with a magnet that closes reed switches as the Control Rod moves in the core. Control Rod position is actually index tube position.

How many reed switches are there?

There are 106 total Reed Switches, with two for each position. There are 53 total positions: ``` 49 Reed Switches - Positions 00-48 1 Reed Switch - Full In 1 Reed Switch - Full Out 1 Reed Switch - Overtravel In 1 Reed Switch - Overtravel Out ``` Each position is actually a pair of Reed Switches so each of the above is times 2.

What temperature does the Control Rod Drive Mechanism High Temperature alarm at?

250 F

Where does the Cooling Water flow enter the Control Rod Drive Mechanism?

Cooling Water enters the Control Rod Drive Mechanism through the Insert Port.

What is the purpose of the Velocity Limiter?

The Velocity Limiter is located at the bottom of the Control Rod and acts as a parachute to slow the rod during a "rod drop" to 3.11 ft/sec.

What is the purpose of the Control Rod D-Handle?

The Control Rod D-Handle allows for disconnecting the Control Rod from the Index Tube(Spud - Spud Nut).