Nuclear Power Plant Systems

Doojeong Lee

Korea Atomic Energy Research Institute (djlee1@kaeri.re.kr

Contents

• Introduction

• Reactor Coolant System

• Reactor Auxiliary Systems

- Chemical and Volume Control System

- Engineering Safety Features

• Safety Injection System

• Shutdown Cooling System

• Containment System

• Safety Depressurization System

• Main Steam and Main Feedwater System

Introduction

Basic PWR Steam Cycle

STEAM

GENERATOR

RCP

REACTOR

CONTAINMENT

TURBINE

CONDENSER

FEEDWATER PUMP

SEA

WATER

ELECTRIC

GENERATOR

BASIC PWR STEAM CYCLE

• A pressurized water reactor(PWR) system utilizes,

basically, two separate heat transfer loops to

accomplish the production of steam for turbine-

generator operation.

– primary system (loop)

– secondary system (loop)

• Primary System

– Reactor vessel, Reactor coolant pumps, Pressurizer, Steam

generator, and Interconnecting piping

• Secondary System

– Shell side of the steam generator, High and low pressure

turbines, Main electrical generator, Main condenser, Condensate

and feed pumps, and Interconnecting piping

General Arrangement

No Building Name

1 Containment Building

2 Auxiliary Building

3 Compound Building

4 Fuel Building

5 Turbine Building

①

② ③

④

⑤

④

⑤

C/B

PA

/B

SA

/B

AC

/B

F/B

T/B

R/B

INT

AK

E

②

Intake

Classification of NPP

• Nuclear Power Plant (NPP)

– NSSS (Nuclear Steam Supply System)

– BOP (Balance of Plant)

– T/G (Turbine Generator)

Nuclear Island

Turbine Island

OPR 1000

• OPR 1000 : Optimized Power Reactor 1000

• Reactor Type : PWR

• Reactor Capacity : 2,825 MWt (1,050MWe)

• Plant Life Time : 40 Years

• Seismic Design

– SSE 0.2g, OBE 0.1g

• Refueling Interval

– 18 Months

• Safety Goals

– CDF 10-4 /reactor year

– CFF 10-5 /year

• Plant availability : 88%

Ulchin Nuclear Power Plants

OPR 1000 Plant Layout (3-D View)

Containment

Turbine Building

Fuel Building

Aux. Building

OPR 1000 Process Systems

Main SteamSafety Valve

AtmosphericDump Valve

Containment

Containment Spray Header

PressurizerSafety Valve

RDT

SafetyDepressurizationSystem

Pressurizer

Control Rod

ReactorVessel

SteamGenerator 2

SafetyInjectionTank

SteamGenerator 1

In-Core Instrument

Train A

Train B

Filter

Core

RefuelingWaterTank

ReactorDrainTank

IonExchanger

VolumeControlTank

ContainmentRecirculationSump

RegenerativeHeat Exchanger

ChargingPump

ChargingControl Valve

AuxiliaryChargingPump

LetdownHeat Exchanger

LetdownOrifice

BoricAcidMake-upPump

Low PressureSafety InjectionPump

High PressureSafety InjectionPump

ContainmentSpray Pump

ContainmentSpray

Hot Leg

Cold Leg

Shutdown CoolingHeat Exchanger

ReheaterDrainTank

ReheaterDrainTank Separator

DrainTank

HP Heater 7 HP Heater 5 HP Heater 5

Stop ValveControl Valve

Intercept ValveIntermediate Valve

HP Heater 7

LPHeater 1

FeedwaterPump

FeedwaterBoosterPump

LP ExtractionSteam

HP ExtractionSteam

Moisture SeparatorReheater

2nd Stage Reheater

1st Stage Reheater

HPExtractionSteam

Turbine Bypassto Condenser

HP TurbineLP Turbine

(3EA) Generator

Condenser

Sea WaterFrom Intake

Sea Waterto Discharge Duct

CondensatePump

Hot Well

DeaeratorStorageTank

Deaerator

DeaeratorStorage TankLevel ControlValve

LP ExtractionSteam

LPExtractionSteam

EconomizerFeedwaterControl Valve

DowncomerFeedwaterControl Valve

Main SteamIsolation Valve

CC

LPHeater 2

LPHeater 3

HP Heater 6

HP Heater 5

ReactorCoolantPump

RCS

CVCS

SIS (ECCS) - HPSI

- LPSI

- SIT (Accumulator)

MS&MFS Containment

SDCS (RHRS)

Reactor Coolant System

Reactor Coolant System (RCS)

• Functions

– Transfer Heat generated

from Reactor to Steam

Generator

– 2nd Barrier of Fission

product Release to

Environment

• Main components

– one reactor vessel

– two steam generators

– four reactor coolant pumps

– one pressurizer

– RCS Piping

– interconnecting pipes to

auxiliary systems such as

CVCS, SCS, and SIS

1B

2A

2B

Steam

Generator 1

Steam

Generator 2

1A

Reactor Vessel

Pressurizer

Reactor

Coolant

Pump

Reactor

Coolant

Pump

RCS Schematic Flow Diagram

Main SteamSafety Valve

AtmosphericDump Valve

Containment

Containment Spray Header

PressurizerSafety Valve

RDT

SafetyDepressurizationSystem

Pressurizer

Control Rod

ReactorVessel

SteamGenerator 2

SafetyInjectionTank

SteamGenerator 1

In-Core Instrument

Train A

Train B

Filter

Core

RefuelingWaterTank

ReactorDrainTank

IonExchanger

VolumeControlTank

ContainmentRecirculationSump

RegenerativeHeat Exchanger

ChargingPump

ChargingControl Valve

AuxiliaryChargingPump

LetdownHeat Exchanger

LetdownOrifice

BoricAcidMake-upPump

Low PressureSafety InjectionPump

High PressureSafety InjectionPump

ContainmentSpray Pump

ContainmentSpray

Hot Leg

Cold Leg

Shutdown CoolingHeat Exchanger

ReheaterDrainTank

ReheaterDrainTank Separator

DrainTank

HP Heater 7 HP Heater 5 HP Heater 5

Stop ValveControl Valve

Intercept ValveIntermediate Valve

HP Heater 7

LPHeater 1

FeedwaterPump

FeedwaterBoosterPump

LP ExtractionSteam

HP ExtractionSteam

Moisture SeparatorReheater

2nd Stage Reheater

1st Stage Reheater

HPExtractionSteam

Turbine Bypassto Condenser

HP TurbineLP Turbine

(3EA) Generator

Condenser

Sea WaterFrom Intake

Sea Waterto Discharge Duct

CondensatePump

Hot Well

DeaeratorStorageTank

Deaerator

DeaeratorStorage TankLevel ControlValve

LP ExtractionSteam

LPExtractionSteam

EconomizerFeedwaterControl Valve

DowncomerFeedwaterControl Valve

Main SteamIsolation Valve

CC

LPHeater 2

LPHeater 3

HP Heater 6

HP Heater 5

ReactorCoolantPump

RCS Arrangement

Cross Section View Top View

원자로

원자로

RCP

RCP

RCP

RCP

가압기

증기

발생기

Westinghouse RCS Arrangements

Two Loop (600MWe) Three Loop (1000MWe)

VVER RCS Arrangement

Four Loop (1000MWe)

Reactor Vessel

• Reactor Pressure Vessel

– A large cylindrical vessel which

serves to contain and support the

reactor core and vessel internals

– Material : carbon molybdenum

steel internally coated with

stainless steel

• Reactor Internals

– Reactor Vessel Head Assembly

– Upper Guide Structure

– Core Support Barrel Assembly

– Lower Support Structure

원자로 제어봉구동장치 (CEDM)

원자로 HEAD(RV CLOSURE HEAD)

상부구조물(UPPER GUIDE

STRUCTURE; UGS)

원자로 출구노즐(OUTLET NOZZLE)

핵연료 지지용기(CORE SUPPRTBARREL; CSB)

하부구조물(LOWER SUPPORTSTRUCTURE; LSS)

원자로 입구노즐(INLET NOZZLE)

핵연료 (CORE)

CEDM

Reactor

Head

Upper

Guide

Structure

Outlet

Nozzle

Inlet

Nozzle

Nuclear

Fuel

Core Support

Barrel

Lower Support

Structure

Flow Path – Reactor Vessel

Bypass Flow

Cold Leg Hot Leg

Reactor Internals

Core Support Structure

Snubber Assembly

Lower Support Structure Upper Support Stucture

Alignment Key

Upper Guide Structure Core Barrel

O-ring

RCS Component Supports

Reactor Vessel

Support Structure RCP Support

Structure S/G Support

Structure

Pressurizer

Support

Structure

Core and Fuel Assembly

• Reactor Core – Fuel assembly

– Control rod • Ag-In-Cd or B4C

• Design data – Total core heat output : 2815 MWt

– Electric Power : 1050MWe

– Number of fuel assemblies : 177

– Fuel length : 150in.

– Equivalent core diameter : 123 inches

Nuclear Fuel

UO2 Power

UO2 Pellet

Cladding

Fuel Assembly Reactor Fuel Rod

Reactor Core

UEF

LEF

SG

Reactor Coolant Pump

• Motor-Driven, 1 stage Vertical

Centrifugal Pump

• Function

– Circulate reactor coolant during

normal operation

– Heat up reactor coolant system

during startup operation

• Sub Components

– Pump Part

• Casing, Impeller, Diffuse, Seal

housing

– Shaft Seal System

– Electrical Motor

RCP Operation Point Determination

Total

System

Resistance

SG

Piping

Reactor Vessel

HEAD, H

FLOW, Q

RCP

Characteristic Curve

Ho

Qo

System Operating Point

H = K Q2

2gA2

RCS Flow Rate Determination

HEAD VS. FLOW RATE

HEAD

(Feet)

System Flow Rate, % of Qdesign

(EOL)

B.E., 8% SG Tubes Plugged

2psi Core Crud

(EOL)

B.E. + 2

(BOL)

B.E., No SG Tubes Plugged

Clean Core

(BOL)

B.E. - 2

RCP Characteristic Curve

Minimum

Operating

Point – Pump

Rated Head

103.5% 108%

Available

Flow Band

Hydrodynamic Shaft Seal

COUPLING

3RD SEAL

2ND SEAL

P4

P3

P2

P1

1ST SEAL

AUXILIARY

IMPELLER

CYCLONE

FILTER

JOURNAL BEARING INJECTION WATER

IMPELLER

CONTROLLED LEAKAGE

FL

OW

RE

ST

RIC

TO

R

RCP

COOLING WATER INTERFACES

SUCTION

PUMP CASING

SEAL INJECTION

HP COOLER

COOLING

WATER

MOTOR CASING

COOLING WATER

SEAL

COOLER

DISCHARGE

COOLING WATER

COOLING WATER

AIR

COOLER

OIL

COOLER

Steam Generator

• Recirculation Heat Exchanger

– Vertical, inverse U-type with integral economizer

• Function

– Interface between primary system

and secondary system

– Produce steam to Turbine Generator

• Sub Components

– Evaporator

• U-Tube : Inconel 690 (Ni-Cr-Fe Alloy)

• Reactor coolant inside, Feedwater

outside of the tube

– Steam Drum

• Centrifugal Separators, Steam Dryers

– Economizer

Steam Dryers

Centrifugal Separators

U-Tube

PWR Steam Generators

Once Through

Steam Generator Recirculating

Steam Generator Recirculating Steam Generator

with a Pre-heater

PWR Steam Generators

VVER-440 Steam Generator

VVER-1000 Steam Generator

• Horizontal Type

SG Flow Path and Economizer

FEEDWATER

INLET

FLOW DISTRIBUTION PLATE

EGG CRATE

DOWNCOMER FLOW

STAY CYLINDER

Economizer TH TC

Function of the Economizer Increase Plant Thermal Efficient

Increase Steam Pressure

Decrease SG Heat Transfer Area

Thermal Effectiveness of

Economizer Concept

T P,HOT

T P,COLD TS

TFW TS

SG INLET SG OUTLET

TE

MP

ER

AT

UR

E

Pinch Point

Pinch Point

Pressurizer

• Function

– Control RCS Pressure

• Maintain reactor coolant at

subcooled state

– Regulate RCS Water Volume

• Compensate reactor coolant

volume change during reactor

transient operation

• Sub Components

– Heaters

– Main and Aux. Spray Nozzle Heaters

Spray Nozzle

Pressurizer Safety Valve (PSV)

Optimization of PSV Design

FLOATING WASHERLIFT STOP

SUPPORT PLATE

INLET NOZZLE

OUTLET NOZZLE

Design Point

Normalized to Design Capacity

Inlet Nozzle

Outlet

Nozzle

Spring Loaded Safety Valve

Control Element Drive Mechanism

(CEDM)

• Magnetic Jack Type

• Function

– Equipment for inserting and

withdrawing control assembly into

reactor core

• Reactor Normal Operation

– Maintain the position of control

assembly as programmed

• Reactor Shutdown/Loss of Electricity

– Insert control rod into reactor core

by gravity

Cable Connector

Internal Pr Housing

Operation Coil Assembly

Control Rod Driving Shaft

Internal latch Assembly

RCS Instrumentation

• Process Instrumentations

– Temperature, Pressure, Level,

Vibration, etc.

– Monitoring, Control, Protection

• Nuclear Instrumentation

– In-core and Ex-core Instrumentation

RCS H/L #1

RCS H/L #2

Start-up CH #2

Start-up CH #1

Safety CH #1

Safety CH #4

Safety CH #3

Safety CH #2

Control CH #2

Control CH #1

Fuel

Ex-Core Instrumentation

In-Core Instrumentations (45)

Reactor Control System

Power Control (Reactivity Control)

RRS

CEDMCS

RPCS

PPCS PLCS

SBCS

FWCS

Steam Bypass Control

Feed Water Flow Control

Pressurizer

Level Control

PressurizerP

ressure

Control

Reactor

Reactor Control Program

Reactor Power (%) Reactor Power (%)

RCS Temperature Control Program Secondary System Pressure

Control Program

Reactor Operation

• Plant Startup

– The series of operation which bring the plant from subcritical cold

shutdown state to hot standby condition

– Filling RCS, Pressurizing, Venting, Heat up, Reactor Startup

• Hot Standby

– Zero power operation with the reactor conditions of the same as

the power operation mode

• Power Operation

– Operation of the reactor at the power level of 15 to 100%

– Reactor is automatically controlled by control systems

• Reactor Shutdown

– The series of operations which bring the RCS from hot standby

condition to a cold shutdown condition in preparation for refueling

or other maintenance operation

OPERATIONAL MODES

Mode Reactivity, Keff

Avg. Coolant

Temperature, oF

% Rated

Thermal Power

1. Power Operation > 0.99 > 500 > 5%

2. Start Up > 0.99 > 500 < 5%

3. Hot Standby < 0.99 > 500 0

4. Hot Shutdown < 0.99 210 < Tavg < 500 0

5. Cold Shutdown < 0.99 < 210 0

6. Refueling < 0.95 < 135 0

P-T Limit Curve

• The object of the P-T limit

curves is to prevent

operation in conditions

which would lead to brittle

characteristics of the

steels.

• RTNDT (Reference

Temperature of Nil

Ductility Temperature)

• Max. RTNDT: 60oF

PR

ES

SU

RIZ

ER

PR

ES

SU

RE

, P

SIA

REACTOR COOLANT TEMPERATURE, oF

Lowest Service Temperature

Inservice Test

System Cooldown

at 100o/Hr

System Heatup

at 100o/Hr

Core Critical

Operation

SDC Operation

RCS and Interfacing System

Steam

Generator

No. 1

Reactor

Vessel

Steam

Generator

No. 2

PRESSURIZER

LOOP 2LOOP 1

Shutdown

Cooling

Shutdown

Cooling

LOOP 2B

LOOP 2AMain

Steam

RCP 2A

RCP 2B

Letdown

(CVCS)

LOOP 1A

RCP 1B

RCP 1A

Main

Steam LOOP 1B

RCGVS

Surge Line

Charging Line

(CVCS)

Safety Valves

(3)Aux. Spray

Reactor Drain Tank (RDT)

Reactor Coolant Gas Vent

System (RCGVS)

Safety Injection

PZR Spray

Control Valves

Containment

Rupture

Disk (2)

SDS Globe & Gate

Valves (2)

CVCS

CVCS : Chemistry and Volume Control System

Chemistry and

Volume Control System (CVCS)

• Function

– Maintain Reactor Coolant Inventory

– Maintain Chemistry of the Reactor Coolant

– Provide Reactivity Compensation (Dilution & Boration)

– Provide seal water to RCP

– Supply cold water to Pressurizer Auxiliary Spray System

– Periodically checking the operability of SIS check valves

• Sub-Systems

– Letdown System

– Charging System

– Makeup System

– Chemical Addition System

– Boron Recycle System

Schematic Flow Diagram of thed

CVCS

Regeneration HX RCP Seal

Aux.

Spray

Letdown

Charging VCT

RWST

MWT

IX

Filter

IX

Letdown HX

Orifice IX

Charging Pump

Aux. Charging Pump

BAT

Containment Aux. Building

CAT

Makeup Pump

ESF

ESF : Engineered Safety Features

Safety Aspects of

Nuclear Power Plant

• Radioactive materials are

produced during nuclear

reaction

- possibility of radioactive

material release to the

environment

• Decay Heat after Reactor

Shutdown

– Right after Rx. shutdown : 7%

– About 1 hour : 1.1%

– About 1 month : 0.1%

Energy

(~200MeV)

+

neutron

235U

+

+ + + + + + +

+

Fission Products

(radio active materials)

Perc

ent

Pow

er

Time (sec)

Fission Products

(radio active materials)

Defense in Depth – Multiple Barriers

First barrier Fuel Pellet

Second barrier Fuel Cladding

Third barrier (25cm Reactor Vessel)

Fourth barrier(6cm steel liner)

Fifth barrier(120cm steel concrete)

Multiple Level of Protection

Stage Objects and Function Key Means

1 Stage • Maintain Normal Power Operation State

• Quality Assurance

• High Quality Maintenance

• Safety Culture

2 Stage • Preventing Accident • Control and Monitoring System

• Reactor Protection System

3 Stage • Accident Mitigation • Engineered Safety Features

• Emergency Operation Procedure

4 Stage • Severe Accident Mitigation • Containment

• Accident Management Plan

5 Stage • Off-site Emergency Response • EAB, EPZ, Emergency Plan

Engineered Safety Features (ESF)

• Function : Mitigates the consequences of design basis accidents

(DBA) by minimizing fuel damage and radioactivity release

– Prevention of progression of DBA into severe accidents

• Safety Injection System (SIS)

– High Pressure Safety Injection (HPSI)

– Low Pressure Safety Injection (LPSI)

– Safety Injection Tank (SIT)

• Shutdown Cooling System (SDCS)

• Aux. Feedwater System (AFWS)

– Atmospheric Dump Valve (ADV)

• Containment System

– Containment

– Containment Spray System (CSS)

• Safety Depressurization System (SDS)

ADV

AFWS

(EFWS)

SIS

(ECCS)

CSS

SDS

PSV

Containment

SDCS

(RHRS)

Safety Injection System (SIS)

• Function

– Supply borated water during LOCA

– Remove decay heat and long term cooling after LOCA

– Supply borated water during RCS overcooling event such as Main

Steam Line Break accident

– Feed and Bleed operation with Safety Depressurization System

• Design Characteristics

– Separate High and Low Pressure Safety Injection

– Automatic actuation upon safety injection signal

– Adopt Single Active Component Failure

– 100% physical independency

– Emergency Power Supply

• HPSI (High Pressure)

• LPSI (Low Pressure)

• SIT (Accumulator)

Schematic Diagram of SIS

Loop1 Hot Leg

Loop2 Hot Leg

Loop1 Cold Leg

SIT

HPSI Pump 2

Refueling Water

Tank

HPSI Pump 1

LPSI Pump 1

LPSI Pump 2

Shutdown Cooling

Heat Exchanger

Containment Recirculation Sump

SIT

SIT

SIT

Loop2 Cold Leg

shutdown cooling system (SCS)

• FUNCTION

– Remove core decay heat during shutdown

• reduce the temperature of the RCS in post shutdown periods from normal

operating temperature to the refueling temperature in conjunction with main

steam and main feedwater system

• Remove decay heat so that RCS should maintain the cold shutdown condition

during reactor shutdown

– Provides low temperature overpressure protection for RCS

– Operate under post accident conditions for cooldown and long term cooling

• Cooldown the RCS following a design basis accident with the SG atmospheric

steam release capacity and the auxiliary feedwater system

• Design Characteristics

– Low pressure safety injection pump is used as the shutdown cooling pump

– The SCS heat exchangers are used with the containment spray system to

cool the containment spray water

Shutdown Cooling System (SCS)

Shutdown

Cooling HX

High Pressure Safety

Injection Pump

LOOP 2

Cold Leg

LOOP 2

Hot Leg

LOOP 1

Cold Leg

LOOP 1

Hot Leg

Low Pressure Safety

Injection Pump

Auxiliary Feedwater System (AFWS)

• Function

– Provide adequate cooling

water to the SG in event of a

loss of main feedwater

• Design Characteristics

– Each auxiliary feedwater

subsystem aligned to feed its

respective SG

– provide enough feedwater to

cool the unit down safely to

the temperature at which the

shutdown cooling system can

be utilized

Auxiliary Feedwater System

(Emergency Feedwater System)

Containment System

• FUNCTION

– Completely encloses the entire reactor and reactor coolant system

– Essentially no leakage of radioactive materials to the environment

– The structure provides biological shielding for both normal and

design basis accident situations

• Design Basis

– Hypothetical loss-of-coolant accidents (LOCA) and

– Secondary system pipe breaks

• Containment sub-systems

– Containment Building

– Containment Heat Removal Systems

– Containment Isolation System

– Combustible Gas Control System

– Containment Ventilation System

Containment Building

• A large dry containment

• Containment structure

– A reinforced concrete base slab

– A pre-stressed concrete cylindrical

shell

– Hemispherical dome

– A reinforced concrete internal

structure

• Leak tight

– The inside face of the slab, shell, and

dome is lined with a leak tight carbon

steel liner

• Aircraft Crash

– Maintain the containment integrity

Dome

Steel Liner

Steel Liner

Steel Liner

Base MAT Sump

Containment heat removal systems

• Containment heat removal systems

– Containment Fan Cooling System

– Containment Spray System

• Containment Fan Cooling System

– Non safety system

– Remove containment heat during post accident period

• Containment Spray System

– Limit the peak pressure in the containment to less then design

pressure during LOCA or a steam break accident inside

containment.

– Removes iodine released on a break of the fuel cladding

following a loss of coolant accident

Schematic Diagram of

the Containment Spray System

Safety Depressurization System

(SDS)

• Function

– SDS is designed to provide a manual means of rapidly depressurizing

the RCS for the highly unlikely event of a total loss of feedwater

(TLOFW)

• Design Characteristics

– Safety system design

– Remote manual operation

– Prevent miss operation by

reactor operators

• Components

– SDS VALVES

• 1 globe and 1gate valve

– Rupture Disk SDS schematic Flow Diagram PZR

RDT

MS&MFWS

MS&MFWS :

Main Steam and Main Feedwater System

Main Steam and

Main Feedwater System

• Main Steam System

– Deliver steam from the secondary side of the NSSS steam generators

to the turbine generator

– Supply auxiliary steam to the following components

• Feedwater pump turbines, auxiliary feedwater pump turbines, the second

stage reheater of the moisture separator reheater (MSR), Turbine Steam

Seal System, Auxiliary Steam System and Process Sampling System

• Main Feedwater System

– Deliver condensate from hotwell to the steam generator

– Condensate System

• from hotwell to the deaerator storage tank

– Feedwater System

• from the deaerator storage tank to the steam generators

• On viewpoint of Energy Conversion

– Reactor Coolant System : Primary System

– Main Steam and Main Feedwater System : Secondary System

Schematic Diagram of

the MS&MFWS

CONDENSER

POLISHER

S/G WET LAYUP RECIRCULATION

LP TBN

CONDENSATE

PUMPS

GRAND SEAL/

AIR EJECTORS

HP

DRAINS

DEAERATOR

STORAGE

TANK(2)

STARTUP

FW PUMP DEAERATOR

2

2

6

3

1

4

S SS

S

CHEM

ADD

5

4 3

HP FW

HEATERS(2)

LP FW

HEATERS(3)

FW PUMPS

TBN(2),MTR(1)

CHEM

ADD

CHEM

ADD

2

STARTUP FEEDWATER RECIRCULATION

1

2

1

1

1

1

1 1

2

2

4

MAKEUP

2

CONDENSATE

STORAGE

TANK 5

AUXILIARY

FEED PUMP

4

MSRHHP TBN

6 2 11 2

1

1

BLOWDOWN

TREATMENT

3

3

4

1 - STEAM

2 - FEED/CONDENSATE

3 - S/G

4 - MAKEUP

S - SAMPLING POINT

S/G

3

S

HP TBN

LP TBN

Condenser

MSRH

Condensate

Pump Startup

Pump

FW Pump

Auxiliary

FW Pump

Steam

Generator S/G Wet Layup Recirculation

Startup Feedwater Recirculation

Main Steam System

Condensate System

Feedwater System

Power Cycle

• The MS&MFS converts the heat energy generated by the nuclear

reactor into electrical energy

• Basic Steam Cycle : Reheat and Regenerative Cycle

– 1 reheater, 1 open feedwater heater and 6 closed feedwater heater

Turbine Generator

• The turbine generator converts the energy of the steam produced in

the steam generators into mechanical shaft power and then into

electrical energy

• The turbine generator consists of a double-flow, high-pressure

turbine and three double-flow low pressure turbines driving a direct-

coupled generator

Moisture Separator/Reheater

• To increase the quality of steam from the high pressure turbine

before entering the low pressure turbine

• Reheating the steam from the high pressure turbine after removing

moisture to increase thermal power efficiency

2nd Stage Reheater

1st Stage Reheater

Moisture Separator Impingement

Plate

Main Condenser

• Condenser is a kind of heat exchanger which condensates steam

expanded from turbine

• It can also remove non-condensable gas contained in the expanded

steam

• Operating Pressure and Temperature : 0.05 bar, 33oC

Condensate and Feedwater Pump

• Condensate Pump (three 50% capacity motor-driven)

– Deliver condensate from the condenser hotwell to the deaerator

• Feedwater booster pumps (three 50% capacity motor-driven)

– deliver condensate from the deaerator storage tank to the suction of the

main feedwater pumps

• Main feedwater pumps (three 50% capacity turbine-driven)

– deliver feedwater to steam generator

• Startup feedwater pump (one motor-driven)

– provides feedwater during shutdown and startup

Pre Heating

228°C

33°C

Extraction Steam

LP A LP B LP C

TO FEEDWATER LINE HDP A

HDP B

STEAM FLOW

FEEDWATER FLOW

DRAIN FLOW

3 3 5 5

5A 5B

6B 6A

4A 4B

A

B

HDT HDT

CONDENSATE

PUMPS

A

B

C

COND “A” COND “B” COND “C”

3A

1A

2A

3B

1B

2B

3C

1C

2C

HP

12 12 9 11 9 11 12 12 9 11 9 11 12 12 9 11 9 11

7 7

Low Pressure Feedwater Heaters

EXTRACTION STEAM INLET

DRAIN INLET

DRAIN OUTLET

CONDENSATE INLET

CONDENSATE OUTLET

HIGH LEVEL DUMP

Sub-cooled Zone Shell Side

High Pressure Feedwater Heaters

EXTRACTION STEAM INLET

DRAIN INLET

Drain to 5th stage Feedwater Heater

FEEDWATER INLET

FEEDWATER OUTLET

Extraction Steam Line

HP/LP TURBINE

MOV

Stop Valve

Stop Check Valve

FEEDWATER HEATER

Heater Drain System

Deaerator

• One deaerator and two deaerator storage tanks are installed to

remove oxygen

Circulating Water System

• Provides cooling seawater to the main condenser for the removal of

the waste heat to the sea as a heat sink

• Chlorination of the circulating water and condenser tube cleaning

– to control biological growth inside the condenser tubes and the growth

of marine organisms in the intake structure

– to remove bio-fouling, sediment, corrosion products, and scaling

Thank you