LC20 Systems RCS

5 gpm down the shaft thru thermal barrier heat exchanger

3 gpm up the shaft lubricating radial bearing and leaking through No. 1 Seal

From EOS-0.1A:

1. RCS Subcooling > 25F (55F for Adverse Containment)

2. SG Pressures - Stable or Decreasing

3. CET - Stable or Decreasing

4. RCS Cold Leg Temp - At Saturation Temp for S/G Pressure

5. RCS Hot Leg Temp - Stable or Decreasing

Indications Only for the 4 RCPs

Oil pressure reaches 600 psig

The No. 1 Seal Bypass Valve should opened only if all the following conditions are met:

• a. RCS pressure is between 100 and 1000 psig
• b. No. 1 Seal Leakoff Valve is opened
• c. No. 1 Seal Leakoff flowrate < 1 gpm
• d. Seal Injection Water flowrate to each RCP >= 8 gpm

Note: Do not open #1 Seal Bypass Valve unless either: Pump Bearing Temp approache 225F or #1 Seal Water Inlet Temp approaches 235F (even if the preceding criteria are met).

NEVER start an RCP in Mode 1 or 2 (SOP 108A)

dP must be mainted at 250 psid across the No. 1 Seal when pumps are started with a PZR steam bubble

dP must be mainted at 200 psid across the No. 1 Seal when pumps are started with PZR solid OR in MODE 3 or 4.

NOTE: RCS pressure of ~325 psig ensures NPSH to RCP

225F Max

190F Max (195F Alarm and Trip)

190F Max (195F Alarm and Trip)

300 Max (Alarm and Trip)

235F Max

• 6 gpm
• To prevent high temp water from reaching No. 1 seal

Remove heat generated in the fuel from the controlled fission process and tranfer the heat to the MSS via S/G.

• 1. Remove head generated in the fuel due to fission product decay.
• 2. Act as a carrier for Boric Acid
• 3. Act as a second barrier against fission-product release to the environment. (Cladding, RCS, Cntmt)
• 4. Improve the neutron economy by acting as a reflector
• 5. Increase the probability of fission by moderating the neutron energy level to the thermal state.

Tavg = 585F (589F)

Thot = 618F (620F)

Tcold = 556F (559F)

Pressure = 2235 psig

Capacity = 95,000 gal (91,000 gal)

Flow Rate = 410,000 gpm (390,000 gpm)

Total of 6% Bypass Flow:

• Nozzle Bypass Flow (1%)
• Baffle Wall Bypass Flow (0.5%)
• Head Cooling Bypass Flow (0.5%)
• Control Rod and Instrument Thimble Bypass Flow (2%)

NOTE: ~94% goes from Cold Leg to Hot Leg

Loops 1 & 4 Cold Legs

Loops 1 & 4 Cold Legs

Connects to each Cold Leg during SI

Each Cold Leg during SI

All four Hot Legs

Hot Legs 2 & 3 during SI Hot Leg Recirc Phase

• All four Cold Legs (Injection)
• Hot Legs 1 & 4 (Suction)

Loop 4 Hot Leg

Loop 3 Intermediate Leg

Between RCP and S/G

Between Rx and RCP

Between RCP and Rx

Loop 1 Intermediate Leg

650F

680F

2485 psig (minus PRT, discharge piping from the PZR PORVs and Safety Valves)

• PRT:
• PORV: 2335 psig
• Safety: 2485psig

• Reactor Vessel
• Closure Head
• Lower Internals
• Upper Internals
• Instrumentation Support Assembly

653F

2335 psig

140F - Alarms on MCB

Inner O-Ring

RCDT

• If inner o-ring leaks:
• put second o-ring in service by NEO closing uRC-8069B (NO) and opening uRC-8069A (NC)

72F measured by RHR

105,000 gpm

Note: Pump develops 288 ft of head at 100,600 gpm.

• Flow provided by CVCS at:
• Higher Pressure (2400 psig)
• Lower Temp (115F)
• 8 gpm (3 gpm up and 5 gpm down)

• Film-riding seal
• Supplies the No. 2 Seal
• Excess Flow goes to Seal Water HX in CVCS (CCP Suction): 3gpm
• Pressure: 2400 psig to 50 psig

• Face-rubbing seal
• Leakage joins with the outer dam lkg of #3 Seal
• Piped to RCDT: 3 gph
• Pressure: 50 psig to 4 psig

• Face-rubbing seal
• Pressure: 10 psig
• Cntmt Sumps: 400 cc/hr
• RCDT: 400 cc/hr

RCP CP: uD3-1

RCP Motor Power: uA1 through uA4

• Normal Ops: uUT
• Outage: uST

• Only ONE #1 Seal Bypass Valve
• All four RCPs share a common Header

Note: All four RCPs have individual #1 Seal Leakoff Valves

Extends coastdown on loss of all AC and prevents de-energized pump from rotating backwards due to reverse flow

Mounted on top of the rotor shaft

• If closed, breaker remains closed
• If open, cannot close breaker
• Cannot trip breaker from the CR

• CCW cools:
• Pump via Thermal Barrier
• Motor via Air

1. Permissive Interlock requires the oil lift pressure to reach 600 psig BEFORE RCP can be started.

2. One minute after RCP begins operation, oil lift pump is secured.

3. Oil pump is not needed when stopping the RCP

There are NO controls, ONLY indication!

• 1. Oil Lift Pump handswitch to Start
• 2. Lift Oil Pressure > 600 psig
• 3. No 86M
• 4. Breaker in CONNECT
• 5. MCB handswitch to Start

• 1. RCP shall not be started in MODE 1 or 2.
• 2. RCP should not be operated continuously until the RCS has been vented.
• 3. Maintain minimum of 15 psig in the VCT to ensure effective backpressure on the RCP #1 Seal and provide proper lubrication of the #2 Seal.
• 4. Frequent start/stop can damage motor windings.
• a. Two successive starts are permitted (5 minutes)
• b. Third start may be made by running a period of 20 minutes or standing idle for a period of 45 minutes.
• c. Only one RCP is started at any one time.
• 5. Seal Injection flow to each RCP must be >6 gpm to prevent high temp water from reaching #1 Seal
• 6. Seal Leakoff flow must be >= 0.2 gpm from #1 seal at ALL times

Lower Seal Water (Pump Radial) Bearing Temp: 225F Max

Seal Water Inlet Temp: 235F Max

Lower Motor (Radial & Thrust) Bearing Temp: 195F (Alarm and Trip)

Upper Motor (Radial & Thrust) Bearing Temp: 195F (Alarm and Trip)

Motor Stator Winding Temp: 300F Max (Alarm and Trip)

RCP #1 Seal Injection Water should not exceed 130F

CCW to RCP oil and air cools and thermal barriers should not exceed 105F

• 50 gal per 1%
• Volume: 1800 ft³

25%

60%

Cold Legs 1 & 4

Hot Leg 4

Intermediate Leg 3

Intermediate Leg 1

• Cold Legs 1 & 4
• Alternates between outages

• Charleigh:
• 18 heater elements
• 416 kW heat capacity

A, B, and D

• A, B (Can be operated from RSP):
• 21 heater elements
• 485 kW heat capacity

D: 18 heater elements, 416 kW heat capacity

• 1. SI
• 2. Low Level (17%)
• 3. Low Bus Voltage

• 1. CL 1 & 4
• 2. Capacity: 450 gpm each
• 3. Air Operated, FC on loss of air or power
• 4. Manual Bypass Valves allow ~1 gpm of spray (this prevents thermal shock to spray nozzle and keep chem & boron at RCS equilibrium)

• 1. Spray comes from CVCS through u-8145 from CCP discharge
• 2. Depressurizes and cools PZR when RCPs aren't running
• 3. Procedural Limits apply to reduce risk of thermal shock to spray line and nozzle

• Lift at 2335 psig
• FC on loss of nitrogen or power
• Discharge to PRT through Common Line
• Minimize challenges to PZR Safety Valves
• Used for Low Temp Overpressure Protection (LTOP)

Note: Some ERGs require PORVs to depressurize RCS when RCPs are not running

2385 psig

• Provide RCS overpressure protection
• Setpoint 2485 psig
• Like PORVs, Safeties discharges to PRT thru common hdr

**** NOTE: POSITION is the ONLY indication for Safeties on the MCB!!! ****

Indications (MCB): Pressure, Level, and Temp

Protected by two rupture discs (91 psid)

Filled (64-88%) with RMUW with N₂ blanket and maintained <113F.

Discharge to PRT is thru sparger BENEATH water lvl

Internal spray and drain are used to cool tank after discharge

• Measures RCS Inventory and Temp (above upper core plate)
• Detects approach to inadequate core cooling

• 2 probe assemblies located in the proximity of CL inlets
• 8 discrete elevations about the core plate

• 1. Normal dTemp between heated and unheated junctions is 90-130F.
• 2. When water level falls, reduced Q_dot of the surrounding steam causes the dTemp to increase.
• 3. This increase indicates the presence of a void in the upper vessel head.

• 1. RVLIS
• 2. Mansell Level Monitor
• 3. Differential Pressure Transmitters (3):
• -Extended Wide Range (above PZR lower level tap)
• -Wide Range (above vessel flange)
• -Narrow Range (RCS loop piping)

• RCP is OPERABLE
• S/G Level is at 38% NR (U1) or 10% NR (U2)

• Unit 1 (Model Delta 76) has Elevated Feedring
• Unit 2 (Model D-5) has Stainless Steel Preheater

Excessive Rx Coolant Leakage

Shutdown Loss of Coolant

• Hi/Lo Lube Oil Level
• - Bearing Temp >=195F

• RCP Vibration
• - Shaft 15 mils increasing at >1 mil/hr or 20 mils
• - Frame 3 mils increasing at >0.2 mils/hr or 5 mils

Loss of Seal Injection (CCW flow to thermal barriers must be > 35 gpm)

Can operate with #2 or #3 Seal failure if other parameters (vibrations, temps, etc) are within limits

• MODE 5 - 3
• Vacuum fill RCS with borated water
• Establish RCS Chemistry
• Draw PZR bubble
• Pressurize and H/U RCS

• MODE 3 - 5
• Borate to Cold Shutdown
• Cooldown to 350F using Steam Dumps
• Cooldown to <350 using RHR

• MODE 6
• Cooldown to < 140F
• RCS Level Monitoring Systems in service
• Rx Vessel Head removed

• MODE 1 & 2
• Power Operations includes:
• Steady State
• Ramp changes < 5% per minute
• Step changes of 10%
• Step load decreases with Steam Dumps < 50% RTP
• Power < 15%: Rx is controlled manually
• Power > 15%: Rx Control System controls

Hot Standby: RCS subcritical & T_ave maintained at 557F

• NOTE:
• RCS pressure at 2235 psig
• PZR level controlled by CVCS

• High Pressure Trip: 2385 psig
• PORV Opens: 2335 psig
• Spray Valves Full Open: 2310 psig
• Spray Valves Start Open: 2260 psig
• Variable Heater Off: 2250 psig
• NOP: 2235 psig
• P-11: 1960 psig

• PORVs Closed: 2315 psig
• B/U Heater On: 2210 psig
• PORVs Blocked: 2185 psig
• P-11: 1960 psig
• Low Pressure Rx Trip: 1880 psig
• Low Pressure SI: 1820 psig

• Fail to accelerate
• Locked Rotor

50

• Installed on each Hot Leg:
• Reactor Power
• Input to T_ave
• Low DNBR and High kW/ft calculators (generate high power Rx Trip and Runback signals)

Compares WR RCS Pressure with the highest CET and RCS temps

Measured by three DP signals

Low flow signal actuates an alarm

2/3 coincedence per loop: Rx Trips

Two fast response RTDs in each cold leg

Provide indication and input to calculate Tave

• T_ave are averaged
• Used for auto control:
• - PZR level
• - Steam Dumps
• - Control Rod movement

• Derived from turbine inpulse pressure and Tave
• T_ave - T_ref used for:
• - Steam Dumps and
• - Control Rod Movement

RTDs used for indication and input signals to LTOP System

• WR Pressures used for:
• - Post-accident operations
• - Input to LTOP system
• - Input for open permissive signals to RHR system loop isolation valves interlock circuits

• Two detectors (one in steam, one in water)
• Surge Line Temp
• Spray Line Temp
• Safety and PORV Discharge Temp
• Level
• Pressure

• PRT:
• - Temp
• - Pressure
• - Level