ECCS LP

• PZR Pressure
• Steamline Pressure
• Containment Pressure
• Manual

< 1829 psig

< 640 psig

> 3.4 psig

If it does not automatically actuate it can be manually triggered

Maintain Rx coolant inventory in order to protect against grosss failure of the fuel cladding

Minimize core damage due to excessive temperature following a LOCA

Provide additional shutdown capability in the event of a Main Steam system break

Limit H2 production to < 1% of total possible from zircwater reaction

Maintain clad oxidation <17% of total clad thickness

Limit peak clad temperature <2200F

Maintain coolable core geometry

Long term core cooling

• Safety Injection pumps
• Pressurized accumulators
• Containment Recirculation Sumps

• Charging pumps
• RHR pumps
• RHR Heat exchangers
• RWST

Auto inject on an SI signal

Supply borated water for ECCS operations or filling of the refueling cavity

Concrete tank with a Stainless Steel liner

Vented to filtered ventilation and vacuum breaker at 8" of water

Located in RWST tunnel

Between containments, outside of fuel handling building

96%

90%

46.7%

12%

• CV @ 2600 psig
• SI @ 1500 psig
• RH @ 200 psig

Pump water from RWST to RCS at system pressure

10 stage centrifugal pump

2600 Psid

• 150 GPMs @ 2500 Psid
• 550 GPms @ 600 Psid

• Motor Driven Gear Pump
• Cooled by SX

364' Aux. Building inside cubicle

Pump borated water from RWST to RCS when RCS pressure drops below pump shutoff head

10 Stage centrifugal

1500 Psid

• 400 GPMs @ 1200 Psid
• 650 GPMs @ 800 Psid

• Shaft driven gear type pump
• Cooled by SX

364' Aux. inside cubicle

Prevents overpressure due to check valve back-leakage

• Provide an immediate source of borated water to the reactor core in the event of a large RCS pipe rupture
• Provides initial surge of cooling water during large RCS pipe ruptures

10,100 gallons

2200-2400 Ppm

• 31 to 63%
• 6995 to 7217 Gallons

602 to 647 Psi

• Cold leg of the RCS
• Isolated by 2 check valves

• Pressurized with Nitrogen
• Partially filled with Borated Water

RWST or AB HUTs

When RCS pressure is less than 1000 psig

Can be bled and fed with the SI pumps to change Cb

426' Level on Containment

• Deliver reactor coolant flow through the RHR heat exchangers to meet plant cooldown requirements
• Supply borated water to the RCS, the suction of the Centrifugal CV pumps and the suction of the SI pumps during an ECCS actuation

Vertically Mounted centrifugal pumps

200 Psid

• 3000 GPMs @ 165 psid
• 5000 GPMs @ 125 psid

346' Aux. in cubicles

Transfer reactor decay heat to the Component Cooling Water System

Two vertically mounted shell and U-tube heat exchangers

RCS

Component Cooling Water

Borated water flows through tubeside

364' to 383' Aux. Building in cubicle

Collect water from a RCS rupture for reuse by ECCS

• Two sumps in each containment
• Covered by Screen to minimize blockage
• 114" Deep

Suction of RHR pump and Containment Spray pump

377' Inside Containment

• RCS
• CVCS
• AB
• RHR

• CV pumps discharge to the cold legs via a common header. This is the HIGH HEAD safety injection flowpath
• Accumulators, RHR pumps and SI pumps discharge to the RCS cold legs via common headers. This is the LOW HEAD safety injection flowpath.
• RHR pumps and SI pumps can also discharge to the RCS hot legs

• During the injection phase, the CV pumps take a suction on the RWST and discharge to the RCS cold legs
• During the recirculation phase, CV pump suction is shifted to take water from the outlet of the RHR Hx.Discharge is still to the RCS cold legs.

• All ECCS pressure relief valves (except the accumulators) relieve to the AB HUT’s
• Accumulators can drain to the AB HUT’s or the RWST.

• During the injection phase, the RH pumps take a suction on the RWST and discharge to the RCS cold legs
• During recirculation phase, the RH pumps take a suction on their respective containment recirculation sump.
• 1A RH pump discharges to the CV pump suction
• 1B RH pump discharges to the SI pump suction, and both pumps discharge to the RCS.

• AC
• DC
• IA
• CC
• Nitrogen
• SX

AOVs

• Shaft seal cooler of the RHR pumps
• Removes heat from RHR Heat Exchangers

• CV pump gear oil coolers
• CV and Si pump lube oild coolers and cubicle coolers

AOVs will fail in a safe position

Spurious Valve Actuation Guidelines

Manually controlled, electrically operated valves where a single failure can result in performing an undesireable mechanical motion.

Disconnect power to these valves after they are manipulated to the correct position

System aligned to auto inject at RCS temperatures > 350 degrees

With the reactor in any other condition other than cold shutdown, the ECCS is aligned to automatically inject water from the SI accumulators and the RWST to the RCS cold legs

• Injection
• Cold Leg Recirculation
• Hot Leg Recirculation

RWST | to | CV pumps | discharge to a common header | to all 4 RCS cold legs.

RWST | to | SI pumps | to all 4 RCS cold legs

RWST | to | RHR | through | RHR Hx’s. (No CC water through the RHR Hx during injection phase) | mixes with | SI pumps | discharges to | All four COLD Legs

SI accumulators | mixes with | RHR and SI pump | discharges to | All four COLD Legs

RWST Low-2 alarm

CNTM Sump | to | RHR Pump | to | RHR Hx – CC removes heat | to | RCS cold legs, CV and SI Suction | Drains to | CNTM Sump

CV and SI Suction | to | RCS cold legs | Drains to | CNTM Sump

CNTM Sump | to | RHR Pump | to | _A RHR Hx – CC removes heat | to | _A and _C hot legs, and to the suction of the CV pumps

CV pumps still injecting into Cold Legs

CNTM Sump | to | RHR Pump | to | _B RHR Hx – CC removes heat | to | suction of the SI pumps

_A SI pump | to | _A and _D hot legs

_B SI pump | to | _B and _C hot legs

Increases Core flow (assuming Cold Leg break)

Prevent boron plating out (due to boiling) which would: Block flow Channels and Reduce heat transfer.

Initiated after Cold Leg Recirc at 5 hrs 50 mins after SI (with 20 min completion time)

Adds borated water to counteract (+) reactivity added by cooldown

Adds mass to RCS to counteract the volume reduction due to cooldown

Feedwater Isolation to minimize cooldown

RCS pressure may remain near NOP due to no RCS leakage

Continued operation of CV pumps will cause PZR PORV to lift

SI will be manually terminated

Circulates the contents of the RWST for samples and temperature control

• < 35 degrees operability due to freezing
• > 100 degrees ability to remove heat

AUTO—the pump and heater cycle on and off based on temperature in the RWST. The pump and heater start at 58°F decreasing and stop at 65°F increasing.

Heater and Pump are not running

Pump runs but heater is off