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Design Control Document/Tier 2ABWR

List o f Tables........................................................................... ............................................. 10.0-iii

List of Figures ....................................................................... ................................................. 10.0-v

10.0 Steam and Po wer Con version System ................................................................................. 10.1-1

10.1 Summary Description ........................................................................................... 10.1-1

10.1.1 Pro tective Features ........................................................................... ........ 10.1-2

10.2 Turbine Gen erator ............................................................................................... 10.2-1

10.2.1 Design Ba ses........................................................................ ...................... 10.2-1

10.2.2 Description ......................................................................... ....................... 10.2-2

10.2.3 Turbin e In tegrity .............................................................................. ...... 10.2-11

10.2.4 Evalua tion .................... .......................................................................... 10.2-14

10.2.5 CO L License Info rma tion .................................................................. .... 10.2-15

10.2.6 Referen ces....................................................................................... ....... 10.2-16

10.3 Main Steam Supply System ............................................................................. ..... 10.3-110.3.1 Design Ba ses........................................................................ ...................... 10.3-1

10.3.2 Description ......................................................................... ....................... 10.3-2

10.3.3 Evalua tion .......................................................................... ....................... 10.3-3

10.3.4 Inspection an d Testing Requ iremen ts.......... .......................................... 10.3-3

10.3.5 Water Chemistry (P WR) .................................................................... ...... 10.3-3

10.3.6 Steam an d Feedwater System Materia ls .................................................. 10.3-4

10.3.7 CO L License Informa tion .................................................................. ...... 10.3-5

10.4 Oth er Features of Steam and Power Con version System ................................... 10.4-1

10.4.1 Main Co nd enser ....................................................................................... 10.4-1

10.4.2 Main Cond enser Evalua tion System ....................................................... 10.4-6

Chapter 10

Table of Contents

Certrec GE

ABWR

DCD R4

Digitally signed by Certrec GEABWRDCDR4DN:o=VeriSign,Inc., ou=VeriSign

Trust Network,ou=www.verisign.com/repository/RPA Incorp.by Ref.,LIAB.LTD(c)98,ou=Persona NotValidated,ou=Digital IDClass 1-Microsoft Full Service,cn=Certrec GEABWR DCDR4,[email protected]:2007.08.3014:36:04 -05'00'


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Table 10.1-1 Summary of Importan t Design Features and P erforma nce Chara cteristics

of th e Steam and Po wer Con version System ....................................................... 10.1-4

Table 10.3-1 Main Steam Supply System Design Da ta ............................................................. 10.3-6

Table 10.4-1 Co nd enser Design Dat a ..................................................................................... 10.4-31

Table 10.4-2 Main Co nd enser Evacua tion System ................................................................. 10.4-31

Table 10.4-3 Circula ting Water System ....................................................................... ............ 10.4-32

Table 10.4-4 Co nd ensate Pur ification System ........................................................................ 10.4-32

Table 10.4-5 Co nd ensate an d Feedwater System Design Data .............................................. 10.4-33

Table 10.4-6 Co nd ensate an d Feedwater System Co mpo nen t Failure Ana lysis...... ............. 10.4-34

Chapter 10

List of Tables


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Figure 10.1-1 Referen ce Steam & Po wer Co nversion System ................................................ 10.1-7

Figure 10.1-2 Reference Heat Balance for Guar anteed Reactor Rating ............................... 10.1-8

Figure 10.1-3 Referen ce Hea t Balan ce for Valves-Wide-Open (VWO) ................................. 10.1-8

Figure 10.2-1 Turbin e Stop Valve Closure Characteristic.................................................... 10.2-17

Figure 10.2-2 Turbin e Cont rol Valve Fast Closure Characteristic....................................... 10.2-18

Figure 10.2-3 Acceptable Range for Con trol Valve Norm al Closure Motion ..................... 10.2-19

Figure 10.2-4 Generator Hydrogen and CO2 System........................................................... 10.2-20

Figure 10.3-1 Main Steam Supply System ............................................................................. . 10.3-7

Figure 10.3-2 Main Turbin e System ........................................................................ ............... 10.3-8

Figure 10.4-1 Main Conden ser Evacua tion System .............................................................. 10.4-35

Figure 10.4-2 Turbin e G land Seal System.................................................... ......................... 10.4-36

Figure 10.4-3 Circula ting Water System.. .............................................................................. 10.4-37

Figure 10.4-4 Cond ensate Pur ification System ..................................................................... 10.4-38

Figure 10.4-5 Cond ensate System.................................................. ........................................ 10.4-40

Figure 10.4-6 Feedwater System .............................................................................. .............. 10.4-42

Chapter 10

List of Figures


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10.0 Steam and Power Conversion System

10.1 Summary Description

The com ponen ts of the Steam and Po wer Con version ( S&PC ) System are designed to

prod uce electrical power utilizing the steam g enerated by the reactor, con dense the

steam into water, and return the water to the reactor a s heated feed water, with a major

portion of its gaseous, dissolved, a nd particulate impurities removed in ord er to satisfythe reactor water q uality requiremen ts.

The S&PC System includes the ma in steam system, the main tu rbin e generato r system,

main cond enser, conden ser evacuation system, turb ine glan d seal system, turbine

bypass system, extraction steam system, cond ensate clean up system, and the cond ensate

and feed water pumping and heating system. The heat rejected to the main cond enser

is removed by a circulating water system and discharged to the power cycle heat sink.

Steam, genera ted in th e reactor, is supplied to th e high-pressure turbine a nd the steam

moisture separators/reheaters. Steam leaving th e high-pressure turb ine passes throug h

a comb ined mo isture separato r/reheater prior to entering the low pressure turbines.

The mo isture separato r dra ins, steam reh eater dra ins, and the dra ins from th e two high

pressure feedwater h eaters are pumped b ack to the reactor feedwater pump suction by

the h eater dra in pumps. The low pressure feedwater hea ter dra ins are cascaded to th e

condenser.

Steam exhausted from the low-pressure turbines is cond ensed and deaera ted in th e

cond enser. The con densate pumps take suction fro m th e cond enser hotwell and deliver


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33% of the rated steam flow is provided to discharge excess steam directly to the

conden ser. Altho ugh the ABWR Stand ard Plan t design is for 33% bypass, this capab ility

could be increased to a full load reject capability without affecting th e Nuclear I sland.

Ind ividual compo nents of the S&PC System a re ba sed o n pr oven co nventiona l designs

suitable for use in large, cen tral station power plan ts.

All auxiliary equipm ent is sized for the maximum calculated unit capability with turbine

valves wide open.

The S&PC System is designed for sustained long-term o pera tion with a h eat input eq ual

to the rated 3919 MWt available from the NSSS when the reactor core is generating its

rated 3926 MW ther mal output. The S&PC System is designed to oper ate at 105% of

maximum gua ranteed turbine thro ttle flow (assumed to correspond to turbine valves

wide open) fo r transients and shor t-term load ing cond itions.

The inlet pressure at the turbine main steam valves will not exceed rated pressure,except when operating abo ve 95% of th e maximum guara nteed turbine flow. It will be

permissible to increase the inlet pressure to 103% of rated pressure, pro vided the

contro l valve position is adjusted so that the r esulting steam flow d oes not exceed the

steam flow th at is obtained when o perating a t rated pressure with contro l valves wide

open.

The n ecessary biological shielding for personn el protection is provided for all rad iation

prod ucing compo nents of th e power conversion system, including th e main turbines,

moisture separato r/reheaters, feedwater hea ters, cond enser and steam jet air ejector.

The reference guaran teed ra ting and valves-wide-open flow qua ntities and fluid en ergy

levels are shown on the turb ine cycle heat balances (Figures 10 1 2 and 10 1 3


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10.1.1.2 Overpressure Protection

The fo llowing compon ents are provided with overpressure protection in accord ance

with the ASME Boiler an d P ressure Vessel Code , Section VIII:

(1) Moisture separator/reheater vessels

(2) Selected low pressure feedwater heaters

(3) High pressure feedwater heaters

( 4) H ea ter d ra in ta nk

10.1.1.3 Turbine Overspeed Protection

Turbin e o verspeed pro tection is discussed in Subsection 10.2.2.4.

10.1.1.4 Turbine Integrity

Turbin e in tegrity is discussed in Subsections 10.2.3 an d 3.5.1.


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Table 10.1-1 Summary of Important Design Features and PerformanceCharacteristics of the Steam and Power Conversion System

Nuclear Steam Supply System, Full Power Operation

Rated reactor core power, MWt 3,926

Rated NSSS power, MWt 3,919

Reactor steam outlet pressure, MPaA 7.17Reactor nominal outlet steam moisture,% 0.1

Reactor inlet feedwater temperature, C 215.6

Turbine-Generator

Nominal Rating, MWe ~1,400

Turbine type Tandem compound, six flow, 132.08 cmlast-stage bucket

1 high pressure turbine

3 low pressure turbines

Operating speed, rad/s 188.5

Turbine throttle steam pressure, MPaA 6.79

Throttle steam nominal moisture,% 0.4

Moisture Separator/Reheaters (MSRs)

N b f MSR i


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Design Conditions:

Normal flow, m3/h ~1817.2

Total head, m 426.72

Rated motor power, kW ~3800

Feedwater Heaters

Low Pressure Heaters

a. No. 1

Number per stage 3

Stage pressure, kPaA 24.5

Duty per shell, kW 22.4 x 103

b. No. 2

Number per stage 3

Stage pressure, kPaA 60.8

Duty per shell, kW 48.85

c. No. 3Number per stage 3

Stage pressure, kPaA 147

3

Table 10.1-1 Summary of Important Design Features and PerformanceCharacteristics of the Steam and Power Conversion System (Continued)


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Reactor Feedwater Pumps

Number of pumps 3 normally operating (3365%), variablespeed

Pump type Horizontal, centrifugal, single stage

Driver type electric motors

Design conditions:

Main pumps:

Normal flow, m3/h ~4202.27

Total head, m ~640.08

Rated motor power, kW ~11,200

Heater Drain Pumps

Number of pumps 2 x 50%

Pump type Horizontal, centrifugal

Driver type Fixed speed motor

Table 10.1-1 Summary of Important Design Features and PerformanceCharacteristics of the Steam and Power Conversion System (Continued)


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DesignControlDocument/Tier2

SummaryDescr

iption

10.1-7

ABWR

Figure 10.1-1 Reference Steam & Power Conversion System

MAIN STEAM

FROM REACTOR

CV

REHEAT STEAM

MS

X Y

6A5A

XY

M

M

M

REACTOR FEED

PUMP

TURBINE

BYPASS

TO

REACTORHEATER DRAIN

TANK

HEATER DRAIN

PUMP

6E 5B

Y X

M

MRECIRC & CLEANUP

TO HOTWELL

SJAE

GSC

OFF-GAS

OFF-GAS

SJAE

CONDENSATE

POLISHERS

CONDENSATE

FILTERS

CONDENSATE

PUMPS

C.W.LP CONDENSER IP CONDENSER

3L 2L

4L 1L

3I 2I

1I4I

3H 2H

1H4H

C.W.

HP CONDENSER

CIV

GEN

LP TURBINELP TURBINELP TURBINE

CIVCIV

MSR A1, A2, B1, B2

MSV


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The following figures are located in Chapter 21 :

Figure 10.1-2 Reference Heat Balance for Guaranteed Reactor Rating

Figure 10.1-3 Reference Heat Balance for Valves-Wide-Open (VWO)


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10.2 Turbine Generator

10.2.1 Design Bases

10.2.1.1 Safety Design Bases

The turb ine genera tor ( T-G ) d oes not serve no r support an y safety function an d h as no

safety design basis. The turb ine gen erator is, ho wever, a potential source of high energy

missiles tha t could d amage safety-related eq uipmen t or structures. The turbine is

designed to minimize the po ssibility of failure of a turbin e blade o r roto r. Turbine

integrity is discussed in Subsection 10.2.3. The e ffects of poten tial h igh energy missiles

are d iscussed in Cha pter 3. In a dd ition, the main steam turbine stop valves are ana lyzed

to dem onstrate structural integrity under safe shutdown earth q uake (SSE) load ing

conditions.

10.2.1.2 Power Generation Design BasesPower Generation Design Basis OneThe T-G is inten ded for eith er ba se load or load

following operation . The gro ss generato r outputs at reference guaran teed reactor

ratin g an d valves-wide-open (VWO) operation ar e given on th e hea t bala nces sho wn on

Figures 10.1-2 and 10.1-3, respectively.

Power Generation Design Basis TwoThe T-G load change cha racter istics are

compatible with the instrumentation and contro l system which coo rdina tes T-G and

reactor operation.

Power Generation Design Basis ThreeThe T-G is designed to a ccept a sudden loss of


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10.2.1.3 Functional Limitations Imposed by the Design or Operational Characteristics ofthe Reactor Coolant System

10.2.1.3.1 Turbine Stop Valve

During a n event resulting in turb ine stop valve fast closure, turbine in let steam flow will

no t be reduced fa ster than tha t sho wn in Figure 10.2-1.

10.2.1.3.2 Turbine Control Valve

During any event resulting in turbine co ntrol valve fast closure, turbine inlet steam flow

will not be reduced faster than that shown in Figure 10.2-2.

The turb ine contro l valve steam flow shutoff rate, upo n a step reduction to zero in

pressure regulation flow deman d ( no resulting bypass steam flow d eman d) , will be

within the region shown in Figure 10.2-3. Any single control system failure or T-G event

will no t cause a faster steam flow reduction th an tha t shown in Figure 10.2-3 witho utinitiating an immediate reactor trip.

The turb ine con trol valves are capable of full stroke opening and closing times no t

greater tha n 7 seconds for ad equa te pressure control perform ance.

10.2.1.3.3 Automatic Load Maneuvering Capability

Within the auto matic load fo llowing region of the po wer/flow operating m ap (Figure

15.0-1), steam flow will auto mat ically respond to a lo ad dem and step as follows:

(1) For positive load dema nd signal changes less than 10% Nuclear Boiler Rated


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Moisture separation and reheating of th e high -pressure turbine exhaust steam is

performed by four com bined moisture separato r/reheaters (MSRs). Two MSRs are

located o n each side of the T-G center line. The steam passes through the low-pressure

turbines, each with fo ur extraction points for the four low-pressure stages of feedwater

heating , and exh austs into the ma in conden ser. In ad dition to th e external MSRs, the

turbines are designed to separate water from th e steam an d d rain it to th e next lowest

extraction point feedwater heater.

The genera tor is a d irect dr iven, th ree-pha se, 60 Hz, 188.5 rad /s synchro no us genera tor

with a water-cooled stator an d h ydro gen coo led roto r.

The turb ine-generato r uses a digital mo nitoring and contro l system which, in

coord ination with th e turbine Steam B ypass and Pressure Co ntrol System, contro ls the

turbine speed, load, a nd flow for startup and norm al operation s. The con trol system

operates the turbine stop valves, control valves, and combined intermediate valves

(CIVs). T-G supervisory instrumentation is provided for operational analysis andmalfunction d iagno sis.

Automa tic contro l functions are programm ed to pro tect the Nuclear Steam Supply

System throug h appropriate corrective a ctions (Section 7.7).

T-G a ccessories include th e bear ing lubr ication oil system, electro hydra ulic contro l

(EHC) system, turning gear, hydrogen and CO 2 system, seal o il system, stator co oling

water system, exhaust hood spray system, turbine gland sealing system, and turbinesupervisory instrument (TSI) system.

The T-G unit and associated piping, valves, and controls are located completely within


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The m ain stop valves are opera ted in an open-closed mod e either by the emerg ency trip,

fast acting valve for t ripping , or by a sma ll solenoid valve for testing. The d isks are to tally

unba lanced a nd canno t open again st full differential pressure. A bypass is provided to

pressurize the belo w seat a reas of the four valves. Spring s are d esigned to close the main

stop valve in approximately 0.20 second under the emergency conditions listed in

Subsection 10.2.2.5.

Each stop valve contain s a permanen t steam strainer to prevent for eign ma tter from

entering th e contro l valves and turb ine.

The co ntrol valves are designed to en sure tight shutoff. The valves are of sufficient size,

relative to their cracking pressure, to require a pa rtial balan cing. Each contro l valve is

operated by a single actin g, spring-closed servomotor opened by a high pr essure fire-

resistan t fluid supplied th rough a servo valve. The co ntrol valve is designed to close in

approximately 0.20 second.

High-Pressure TurbineThe H P turb ine receives steam th rough four steam leads, one

from each control valve outlet. The steam is expanded axially across several stages of

stationa ry and moving blades. Steam pressure immed iately downstream o f the first stage

is used as a load reference signal for reacto r contro l. Extraction steam from th e turbine

supplies the last stage of feed water heating . H P turb ine exha ust steam is collected in

eight cold rehea t pipes, four at each end of the turb ine. Most of the exh aust steam is

routed to th e MSR inlet, but pa rt of it is diverted a nd supplies the n ext to last stage offeedwater heating.

MoistureSeparator ReheatersFour horizontal cylindrical-shell combined moisture


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which share a co mmo n casing. Altho ugh they utilize a common casing, th ese valves ha ve

entirely separate operating mechan isms and contro ls. The fun ction o f th e CI Vs is to

protect the turb ine aga inst overspeed from steam a nd water energy stored between the

main stop an d con trol valves and the CI Vs. On e CIV is located on each side of each LP

turbine.

Steam from the MSRs enters the single inlet of each valve casing, passes through the

permanent basket strainer, past the intercept valve and stop valve disks, and enters theLP turb ine thro ugh a single inlet. The C IVs are located as close to th e LP tur bine as

possible to limit the amo unt o f uncon trolled steam available for overspeeding th e

turbine. U pon loss of load , the intercept valve first closes then th rottles steam to th e LP

turbine, as required to contro l speed and mainta in synchro nization. It is capable of

open ing a gain st full system pressure. The in termedia te stop valves close on ly if the

intercept valves fail to operate properly. These valves are capable of opening against a

pressure d ifferen tial of appro ximate ly 15% of th e maximum expected system pressure.The interm ediate stop valve an d intercept valve are designed to close in approximately

0.2 second .

Low-Pressure TurbinesEach LP turb ine receives steam fro m two C IVs. The steam is

expan ded axially across several stages of stationary and moving buckets. Turbin e stages

are n umbered consecutively, starting with the first HP turbine stage.

Extraction steam from the LP turbines supplies the first four stages of feedwaterheating . A fifth extraction stage ma y be provided to remove moisture an d pro tect the

last-stage buckets from ero sion ind uced by water d rop lets. This extraction is drained

directly to th e cond enser


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The ro tor bo dy and shaft is machined from a single, solid steel forging. D etailed

examination s include:

(1) material property checks on test specimens taken from the forging;

(2) photomicrographs for examination of microstructure;

(3) magnetic particle and ultrasonic examination;

(4) surface finish tests of slots for indication o f a stress riser.

Bulk Hydrogen SystemThe bulk hydrogen and CO 2 system is illustrated on

Figure 10.2-4. The hydro gen system is designed to provide th e n ecessary flow a nd

pressure at the main g enerato r for purging carb on d ioxide during startup and supply

makeup hydrogen for generator leakage d uring normal operation.

The system con sists of hydro gen supply piping with all th e n ecessary valves,

instrumenta tion, ga s purity measuring eq uipment, hydrog en ga s dryers, and bulk

hydrogen storage unit.

Fires and explosions during filling and /or purging of the gen erator a re prevented b y

inerting the generator with CO 2 so that a flammable mixture of hydrogen and oxygen

cannot be produced. Unneeded hydrogen is vented outside through a flame arrestor.

The bulk hydrogen system utilizes the guidelines given in EPRI report NP-5283-SR-A

with respect to these portions of th e guidelines involving hydrog en th at d o n ot d eal

specifically with th e H WC system Specifically the bulk hydro gen system piping an d


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10.2.2.3 Normal Operation

During n orma l operation, th e main stop valves and CIVs are wide open. O peration o f

the T-G is under th e con trol o f th e Electro-H ydraulic Co ntrol (EH C) System. The EHC

System is comprised of three basic subsystems: the speed control unit, the load control

unit, and the flow control unit. The no rmal function o f the EH C System is to gen erate

the po sition signa ls for the fo ur ma in stop valves, four ma in con tro l valves, and six CIVs.

10.2.2.4 Turbine Overspeed Protection System

In addition to the normal speed control function provided by the turbine control

system, a separate turbine overspeed protection system is included. The turbine

overspeed system is a highly reliable and redundant system which is classified as non-

safety-related.

Pro tection aga inst turbine overspeed is provided b y the mechan ical overspeed trip an d

electrical backup overspeed trip. Redundancy is achieved by using at least two

independ ent cha nn els from the signal source to th e output device. The sensing device,

line and o utput device are of a d ifferent nature for ea ch individual chann el in ord er to

increa se reliability.

The overspeed sensing devices are located in the fro nt bea ring standa rd a nd, th erefore,

are protected fro m the effects of missiles or pipe b reak. The h ydraulic lines are fail-safe;

that is, if on e were to be bro ken, loss of hydraulic pressure would result in a turbine trip.The electric trip signa ls are red und ant. O ne circuit could be disabled by dama ge to the

wiring, but th e other system is fail-safe (i.e., lo ss of signal results in a turbin e trip) . These

f t id inh nt t ti n g in t f il f th d t m d b


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(2) Intermediate stop valves/Intercept valves

(3) Primary speed control/Backup speed control

(4) Fast acting solenoid valves/Emergency trip fluid system

(5) Speed control/Overspeed trip/Backup overspeed trip

The m ain stop valves and con tro l valves provide fu ll redun da ncy in tha t these valves are

in series and have completely independ ent opera ting contr ols and operating

mechan isms. Closure of eith er all four stop valves or all four con tro l valves shuts off all

main steam flow to the HP turbine. The combined intermediate stop and intercept

valves are also in series and have completely independ ent o perating contro ls and

operating mechanisms. Closure of either valve or both valves in each of the six sets of

combined intermediate stop a nd intercept valves shuts off a ll MSR outlet steam flow to

the three LP turb ines.

The speed co ntrol un it utilizes at lea st two speed signals. An increase in turbine speed

tend s to close the con tro l valves. Loss of two speed signals will initiate a turbin e trip via

the Emergency Trip System (ETS).

Fast acting solenoid valves initiate fast closure of control valves under load rejection

cond itions that migh t lead to rapid ro tor a cceleration. The ETS initiates fast closure of

the valves whether th e fast-acting solenoid valves work or no t.

If speed control should fail, the overspeed trip devices must close the steam admission

l t t t bi d C t d d d f il f d ig f th


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(3) Low condenser vacuum

(4) Low lube oil pressure

(5) LP turbine exhaust hood high temperature

(6) High reactor water level

(7) Thrust bear ing wear

(8) Overspeed (electrical and mechanical)

(9) Manual trip handle on front standard

(10) Loss of stator coolant

(11) Low hydraulic fluid pressure

(12) Any generator trip

(13) Loss of EHC electrical power

(14) Excessive turbine shaft vibration

(15) Loss of two speed signals

All of the a bove trip signals except vibrat ion a nd man ual trips use 2/3 or 2/4 coinciden t

trip logic.


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(6) Shell temperature

(7) Valve posit ions

(8) Shell and rotor differential expansion

(9) Shaft speed, electrical load, and control valve inlet pressure indication

(10) Hydrogen temperature, pressure, and purity

(11) Stator coolant temperature and conductivity

(12) Stator-winding temperature

(13) Exciter air temperatures

(14) Turbine gland sealing pressure

(15) Gland steam condenser vacuum

(16) Steam chest pressure

(17) Seal oil pressure

10.2.2.7 TestingThe electrical and mechanical overspeed trip devices can be tested remotely at rated

speed, und er load, by means of controls on th e EHC test panel. Operation o f the


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(8) Remote t rip solenoids

(9) Lubricat ing oil pumps

(10) Control fluid pumps

10.2.3 Turbine Integrity

10.2.3.1 Materials Selection

Turbin e roto rs an d pa rts are mad e from vacuum melted or vacuum degassed Ni-Cr-Mo-

V alloy steel by processes which minimize flaw occurrence and provide adequate

fracture toug hness. Tramp elements are contro lled to th e lowest practical

concentra tions consistent with goo d scrap selection and melting practice, and

consistent with ob taining a deq uate initial and long-life fracture toughn ess for the

environmen t in which th e parts operate. The turbin e materials have the lowest fracture

appeara nce transition temperatures (FATT) an d highest Cha rpy V-no tch ener gies

ob tainable, o n a co nsistent b asis, from water q uench ed Ni-Cr-Mo-V material at the sizes

an d strength levels used. Since actual levels of FATT and Ch arpy V-no tch energy vary

depend ing upon th e size of the part, an d the location within the part, etc., these

variations are ta ken into account in accepting specific forgings for use in turbines for

nuclear application. The fracture appearance transition temperature (50% FATT), as

ob tained f rom Ch arpy tests perfo rmed in accord an ce with specification ASTM A-370,

will be n o h igher tha n -17.8C fo r low-pressure turb ine d isks. The C ha rpy V-no tchenergy at th e minimum operating temperature o f each low-pressure disk in the

tang ential direction should be at least 81.4 Nm.


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Turbine opera ting proced ures are employed to preclude brittle fracture at startup by

ensuring that m etal temperatures are (a ) ad equa tely abo ve the FATT, and (b) as

defined abo ve, sufficient to mainta in the fra cture toughn ess to tangen tial stress ratio at

or abo ve 10 . Sufficient warmup time is specified in the turbine operating

instruction to assure tha t tough ness will be adeq uate to prevent brittle fracture dur ing

startup.

10.2.3.3 High Temperature Properties

The operat ing tem pera tures of the h igh-pressure ro tors are below the stress ruptur e

rang e. Therefore, creep-rupture is no t a significant failure m echanism.

Basic stress and creep-rupture d ata are o btained in standa rd labora tory tests at

appropriate temperatures with eq uipment a nd procedures consistent with ASTM

recom men da tion s in Referen ce 10.2-2, Subsection 10.2.6.

10.2.3.4 Turbine Design

The turb ine assembly is designed to withstand n orma l cond itions and anticipated

transients, including those resulting in turbine trip, without loss of structural integrity.

The d esign o f th e turbine assembly meets the following criteria:

(1) Turbine shaft bearings are designed to retain their structural integrity under

norm al operating load s and anticipated tran sients, including th ose leading toturbine trips.

(2) The multitude of natural critical frequencies of the turbine shaft assemblies

m m


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10.2.3.5 Preservice Inspection

The preservice procedures and acceptance criteria are as follows:

(1) Forgings are rough machined with minimum stock allowance prior to h eat

treatment.

(2) Each finished m achined rotor is subjected to 100% volumetric (ultrasonic),

and surface visual examinations, using established acceptance criteria. These

criteria a re mo re restrictive tha n those specified for Class 1 compon ents in th e

ASME Boiler and Pressure Vessel Code, Sections III and V, and include the

requiremen t that subsurface sonic ind ications are either removed or

evaluated to en sure that th ey will not gro w to a size which will compromise the

integrity of the unit during its service life.

(3) All finished ma chined surfaces are subjected to a magnetic particle test withno flaw indications permissible.

(4) Each fully bucketed turbine rotor assembly is spin tested at the h ighest

ainticipated speed resulting fro m a loss of loa d.

Add itional preservice inspections include air leakage tests performed to determine that

the hydrogen cooling system is tight before h ydro gen is introd uced into the gen erator

casing. The hydrog en purity is tested in th e genera tor a fter hydrogen has beenintrod uced. The gen erator wind ings and all motors are megg er tested. Vibration tests

are perform ed on all motor-driven eq uipment. H ydro static tests are perform ed on all

l All i ing i t t d f l k M t t d l f t l k


25/86

Rev. 0


(3) 100% visual examination of couplings and coupling bolts.

The inservice inspection of valves important to overspeed protection includes the

following:

(1) All main stop valves, control valves, extraction no nreturn valves, and CIVs will

be tested un der load . Test contro ls installed on the main contro l room turb ine

pan el permit full stroking o f th e stop valve, con tro l valves, and CIVs. Valveposition ind ication is provided o n th e panel. Some loa d red uction is necessary

before testing main stop an d con trol valves, and CIVs. Extraction no nreturn

valves are tested by equa lizing air pressure across the air cylinder. Movement

of th e valve arm is observed upo n a ction o f the spring closure mechanism.

(2) Main stop valves, control valves, extraction no nreturn valves, and CIVs will be

tested by the CO L applicant in accorda nce with the BWROG turbine

surveillance test pro gram, by closing each valve and observing b y the valve

position indicator that it moves smoothly to a fully closed po sition. C losure o f

each main stop valve, control valve and CIV during test will be verified by

direct observation of the valve mo tion.

Tightness tests of the m ain stop a nd contro l valves are perform ed a t least once

per ma intenan ce cycle by checking th e coastdown characteristics of the

turbine fro m n o loa d with ea ch set of four valves closed a lternately.

(3) All main stop valves, main contro l valves, and C IVs will be inspected on ce

during th e first three refueling or extended m aintena nce shutd owns.


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The turb ine is designed, constructed, an d inspected to minimize the po ssibility of any

major component failure.

The turbine has a redundant, testable overspeed trip system to minimize the possibility

of a turbine o verspeed event.

Unrestrained stored energy in the extraction steam system ha s been reduced to a n

acceptable minimum by the ad dition o f no nreturn valves in selected extra ction lines.

The T-G equipmen t shielding requiremen ts and th e metho ds of access contro l for a ll

areas of the Turbine Building ensure that the dose criteria specified in 10CFR20 for

operating personnel are not exceeded.

All areas in proximity to T-G equipmen t are zoned according to expected occupancy

times and radiation levels anticipated und er norm al operating con ditions.

Specification of the various radiation zon es in a ccordan ce with expected occupancy is

listed in Chapter 12.

If d eemed n ecessary during unusual occurrences, the o ccupancy times for certain a reas

will be reduced by administrative controls enacted by health physics personnel.

The design b asis operating con centrations of N-16 in the tu rbine cycle are ind icated in

Section 12.2.

The con nection b etween the low-pressure turbine exha ust ho od and the con denser is

made by means of a stainless steel expansion joint


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10.2.5.2 Turbine Design Overspeed

The C OL applicant will provide th e basis for th e turbine overspeed a s required b y

Subsection 10.2.3.4(4).

10.2.5.3 Turbine Inservice Test and Inspection

The C OL applicant will provide th e turbine inservice test an d inspection req uirements

as no ted in Subsection 10.2.3.6.

10.2.6 References

10.2-1 J. A. Beg ley and W.A. Log sdo n, Westingho use Scientific Pa per 71-1E7 MSLRF-

P1.

10.2-2 ASTM Section III, Vol 03.01, E139-83 Stand ard P ractice for Cond ucting

Creep, Creep Rupture and Stress Rupture Tests for Metallic Materials.


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40

60

80

100

TSTEAM

FLOW,PERCENTOFINITIALSTEAMFLOW

ACCEPTABLE REGION


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100

80

60

40

TSTEAMFL

OW,PERCENTOFINITIALS

TEAMFLOW

ACCEPTABLE REGION FOR TURBINE CONTROL VALVEFAST CLOSURE RESPONSE


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P =

TV =

INITIAL STEAM FLOW,PERCENT NUCLEAR

BOILER RATED

ACTUAL CONTROL

VALVE FULL STROKECLOSURE TIME

SLOWEST

0.025P

TV

(TV 0.5)/100P

T1 =

T2 =

T3 =

R =

(ALL TIME UNITS IN SECONDS)

100 1000T3

(TV 1.5)P

ACCEPTABLE REGION FOR

NORMAL CLOSURE OFTURBINE CONTROL

VALVES

100

R

80

60

40

WA

TTURB

INEINLET(PERCENTOFINITIALSTEAMFLOW)


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Rev.0

DesignControlDocument/Tier2

10.2-20

TurbineGenerator

ABWR

Figure 10.2-4 Generator Hydrogen and CO2 System

H2 SEAL OIL UNIT

VACUUM TANK

TO VACUUMPUMP

GASDRYER

FROM

STATORWINDING

COOLINGWATERSYSTEM

LS

F1

FROM CO2 SYSTEM

FA

FLEXIBLE FILLCONNECTION

GASEOUSHYDROGENSTORAGE

CYLINDERS

RUPTUREDISC

GUARDPIPESEAL

TURBINE ROOMOUTSIDE WALL

GUARDPIPESEAL

GENERATORCASING

H2 MANIFOLD

CO2 MANIFOLD


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10.3 Main Steam Supply System

The function of the Main Steam Supply System is to convey steam generated in the

reactor to th e turbine plant. This section d iscusses that po rtion of the m ain steam supply

system b ound ed by, but do es not include, the seismic interface restraint, turbine stop

valves an d turb ine b ypass valves. This por tion do es include the steam a uxiliary valve(s).

This portion of the main steam supply system is designated as the turbine main steam

system.

The main steam line pressure relief system, main steamline flow restrictors, main steam-

line isolation valves (MSIVs), and main steam piping from the r eactor n ozzles through

the o utbo ard MSIVs to th e seismic interfa ce restraint are described in Subsections 5.2.2,

5.4.4, 5.4.5, an d 5.4.9, respectively.

10.3.1 Design Bases

10.3.1.1 Safety Design Bases

The Main Steam Supply System is not required to effect o r support safe shutdown o f the

reactor o r to perfo rm in th e operation of rea ctor safety features; however, the supply

system is designed:

(1) To accommodate operational stresses such as internal pressure and dynamic

loads without failures.

(2) To provide a seismically analyzed fission product leakage path to the main

condenser.


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Main steam piping fro m the seismic interface restraint to the ma in stop, main turbin e

bypass, including the steam auxiliary valves(s) is analyzed to demonstrate structural

integrity und er safe shutdown earth qua ke (SSE) load ing cond itions. Refer to

Subsection 3.2.5.3 for seismic classification for the lines.

10.3.1.2 Power Generation Design Bases

Power Generation Design Basis OneThe system is designed to d eliver steam f rom the

reactor to the turb ine-generato r system fo r a rang e of flows and pressures varying from

warmup to r ated co nd itions. It also provides steam to the reh eaters, the steam jet air

ejectors, the turbine glan d seal system, the offga s system an d th e dea erating section of

the m ain con denser an d th e turbine b ypass system.

10.3.2 Description

10.3.2.1 General Description

The Main Stea m Supply System is illustrated in Figure 10.3-1. The system d esign d ata is

pro vided in Table 10.3-1. The main stea m pipin g con sists of four 700A pipe size

diameter lines from the o utboa rd MSIVs to the m ain turb ine stop valves. The fo ur ma in

steamlines are connected to a head er upstream of th e turbine stop valves to permit

testing of the MSIVs during plant o peration with a minimum loa d red uction. This

head er arran gement is also provided to ensure that th e turbine bypass and other m ain

steam supplies are con nected to operating steamlines and not to idle lines. The m ainsteam pr ocess downstream of the turb ine stop valves is illustrated in Figure 10.3-2.

The d esign pressure an d tem perature o f the main steam piping is 8.62 MPaG and


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See Subsection 10.3.7.2 for C OL license informa tion pertaining to allowable MSIV

leakage.

10.3.2.2 Component Description

The Main Steam Supply System lines are mad e of carbon steel and are sized fo r a norm al

steady-state velocity of 45.72 m/s, or less. The lines are designed to permit hydrotesting

following construction and major repairs without a dd ition of tempo rary pipe supports.

10.3.2.3 System Operation

Normal OperationAt low plan t power levels, the Main Stea m System m ay be used to

supply steam to the turbine g land steam seal system. At high plan t power levels, turbin e

gland sealing steam is norm ally supplied from the h igh pressure heater drain tank or

related turbine extraction.

Steam is supplied to the crossaro und steam reh eaters in the T-G system when the T-Gload exceeds appro ximate ly 15% and supply steam pressure is con tro lled by regulatin g

valves in th e 15 to approxima tely 60% load ran ge.

If a la rge, ra pid red uction in T-G load occurs, steam is bypassed d irectly to th e

conden ser via the turb ine bypass system (see Subsection 10.4.4 for a description of th e

turb ine bypass system) .

10.3.3 Evaluation

All componen ts and piping for the m ain steam supply system a re d esigned in

accorda nce with th e cod es and stand ards listed in Section 3.2. This ensures that th e


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10.3.6 Steam and Feedwater System Materials

Steam an d feedwater com ponen t ma terials are id entified in Table 5.2-4.

10.3.6.1 Fracture Toughness of Class 2 Components

The fra cture tough ness properties of the ferritic materials of these compon ents will

meet the requirements of NC-2300, Fracture Toughness Requirements for Materials

(Class 2) of ASME Code Section III, as invoked by Regulatory Guide 1.26, QualityG roup Cla ssification an d Sta nd ard s for Water-, Steam -, an d Ra dioactive-Waste-

Con taining Co mpon ents of Nuclear Power Plants. This also includes the portion o f

the m ain steam supply system defin ed in Section 10.3.

10.3.6.2 Materials Selection and Fabrication

The materials specified for use in Class 2 components will conform to Appendix I to

ASME Cod e Section II I, and to Pa rts A, B, an d C o f Section I I of th e Cod e.

Regulatory Guide 1.85, Cod e Case Acceptab ility ASME Section I II Mater ials, describes

acceptable code cases that will be used in co njunction with th e ab ove specifications.

The fo llowing criteria a re applicable to a ll componen ts:

(1) Regulatory Guide 1.71, Welder Qualification for Areas of Limited

Accessibility, provides the following criteria fo r assuring the in tegrity of weldsin loca tion s of restricted d irect physical an d visual accessibility:

(a) The performance qualification should require testing of the welds when


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or d emineralized water are an acceptable source of water for final cleaning or

flushing of fin ished surfaces. The o xygen conten t of the water in th ese vented

tanks need not be controlled.

(3) Acceptance criteria for nondestructive examination of tubular products are

given in ASME Code Section III, Paragraphs NC 2550 through 2570.

10.3.7 COL License Information10.3.7.1 Procedures to Avoid Steam Hammer and Discharge Loads

The CO L applicant will provide operating and mainten ance proced ures that include

adeq uate precautions to a void steam ha mmer a nd discharg e loads (Subsection 10.3.3).

10.3.7.2 MSIV Leakage

The CO L applican t will provide the amo unt o f allowab le MSIV leakage fo r review by theNRC ( Subsection 10.3.2).


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Table 10.3-1 Main Steam Supply System Design Data

Main Steam Piping

Design flow rate at 6.79 MPaA

and 0.40% moisture, kg/h

~7.71E+06

Number of lines 4

Nominal diameter 700A

Minimum wall thickness, mm 38.1

Design pressure,MPaG 8.62

Design temperature, C 302

Design code ASME III, Class 2

Seismic design Analyzed for SSE design

loads


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Rev.0

D

esignControlDocument/Tier2

MainSteamSupp

lySystem

10.3-7

ABWR

Figure 10.3-1 Main Steam Supply System

M

M M

CV CV

CV CV

CV CV

PSV

PSV

FE FE

SUPPRESSION POOL

ACCU

M.A/S

N/S

RPV

CV CV

DRYWELL

MAIN STEAM LINE

MAIN STEAM LINE

MAIN STEAM LINE

MAIN STEAM LINE

NOT IN SCOPE

ABOVE SEATDRAINS TO

CONDENSER

STEAMAUXILIARY

VALVE (S)

TO TURBINE

GLANDSEAL

SYSTEM

TO REHEATER A

TO REHEATER C

TURBINESTOP VALVES

TOM

AIN

TURBINE

TURBINE BYPASS VALVES

TO CONDENSER

TO OFFGAS SYSTEM A

TO STM JET AIR EJECT A

TO OFFGAS SYSTEM B

TO STM JET AIR EJECT B

TO CONDENSER SPARGER

TO REHEATER B

TO REHEATER D

FE FE

DPV

TORCIC

ACCUM. A18


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Rev.0

D


10.3-8

MainSteamSupplySystem

ABWR

Figure 10.3-2 Main Turbine System

MAIN STEAM LINE

MAIN STEAM LINE

MAIN STEAM LINE

MAIN STEAM LINE

TURBINE

STOP VALVES

TURBINE

CONTROL VALVES

HIGH PRESSURE TURBINE

EXHAUSTTO MSR A1

EXHAUSTTO MSR A2

EXHAUSTTO MSR A2

EXHAUST

TO MSR A1

TO SJAE AAND SJAE B

EXHAUSTTO MSR B1

EXHAUST

TO MSR B2

EXHAUSTTO MSR B2

EXHAUSTTO MSR B1


40/86

Rev.0

D


MainSteamSupp

lySystem

10.3-9

ABWR

Figure 10.3-2 Main Turbine System (Continued)

A

CIV CIV CIV

L P TURBINE HL P TURBINE IL P TURBINE J

CIV CIV

MOISTURESEPARATOR

REHEATER A2

MOISTURESEPARATOR

REHEATER B1

MOISTURESEPARATOR

REHEATER B2

MOISTURE SEPARATORREHEATER A2

LCL

TO

CONDENSER

LCW

P2

M

PCW MP1 RSSV

MAIN STEAM

RSWLVPWC

MP2P1

M

MFO

OPERATING VENT

FROM FBW *6A

FROM HP TURBINE

EXHAUST

FROM FBW *5A

MOISTURESEPARATOR

DRAINTANKA1

TO MTR

DRAIN TANK TO FBW *6A

TOCONDENSER

TO

CONDENSER

FROM FBW *6A

FROMFWB

*6A LSW

LCL LCWREHEATERDRAINTANK

A1

FROMFBW

*6A LSW NOMINAL C&I DESIGN,REDUNDANCYNOTSHOWM

FROMHBT LSW

CIV

/10

/10


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10.4 Other Features of Steam and Power Conversion System

This section provides discussions of each of the principal design features of the Steam

and Power C onversion System.

10.4.1 Main Condenser

The m ain co nd enser is the steam cycle heat sink. During norm al opera tion, it receives,

cond enses, dea erates and holds up fo r N-16 decay the ma in turbine exhaust steam, a nd

turb ine bypass steam whenever th e turb ine bypass system is opera ted. The ma in

cond enser is also a collection po int for other steam cycle miscellaneo us drains and

vents.

The ma in con denser is utilized a s a heat sink in the initial phase of reactor cooldo wn

during a n ormal plant shutdown.

10.4.1.1 Design Bases

10.4.1.1.1 Safety Design Bases

The ma in cond enser does not serve or support an y safety function an d h as no safety

design basis. It is, however, designed with necessary shielding and controlled access to

protect plant personnel from radiation. In addition, the main condenser hotwell

provides a ho ld-up volume for MSIV fission prod uct leakage. The suppor ts and a nchors

are designed to withstand a safe shutd own earthq uake.

10.4.1.1.2 Power Generation Design Bases


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Oth er flows occurring period ically or continuously originate fro m ( 1) the minimum

recirculation flows of the reactor feed pumps, and con densate pumps, (2) feedwater

line startup flushing, (3) turb ine eq uipment clean dra ins, (4) low-point d rains, (5)

deaera ting steam (6) makeup, etc.

During transient cond itions, the cond enser is designed to receive turbine bypass steam

and feedwater hea ter an d d rain ta nk high-level dumps. These drain tanks include th e

moisture separato r an d r eheater d rain ta nks. The con denser is also d esigned to receiverelief valve d ischarges an d any neccesary venting from moisture separato r/reheater

vessels, feedwater heater shells, the gland seal steam header, steam seal regulator, and

various other steam supply lines. Spray pipes and baffles are designed to provide

protection of th e conden ser tubes and compon ents from high energy inputs to the

cond enser. At startup, steam is admitted to th e con denser shell to assist in cond ensate

deaera tion. The cond ensate is pumped fro m the con denser hotwell by the cond ensate

pumps described in Subsection 10.4.7.

Since the main co nden ser opera tes at a vacuum, an y leakage is into th e shell side of th e

main con den ser. Provision is made fo r detection o f circulating water leakage into the

shell side o f the main cond enser. Water leakage is detected b y measuring th e

cond uctivity of sample water extracted b eneath the tub e bun dles. A leak will allow the

circulating water to dra in down th e tube bund les and be collected for sampling.

Sampling meth ods are described in Subsection 9.3.2. Radioactive leakage to the

atmosphere cannot occur.

Air inleakage an d no ncon densable gases, including hydrogen and oxygen gases

contain ed in the turb ine exhaust steam d ue to dissociation of water in th e reactor are


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H otwell level controls provide auto matic makeup or rejection of cond ensate to

mainta in a nor mal level in the cond enser hotwells. O n low h otwell water level, the

makeup control valves open a nd a dmit cond ensate to the hotwell from the cond ensate

storag e tank. When the ho twell is broug ht to within norm al operating rang e, the valves

close. O n h igh water level in th e ho twell, the con densate reject control valve open s to

divert conden sate from th e conden sate pump discharge (do wnstream of th e polishers

and auxiliary cond ensers) to the con den sate storage tan k; rejection is stopped when the

hotwell level falls to within normal operating range. The hotwell level signals andcontro ller will be at least triply and d ual redun dan t to assure the availibility of th e

cond ensate pumps.

During th e initial cooling period after plant shutdo wn, the main con denser removes

residual hea t from the rea ctor coolan t system via the turbine bypass system. Ho wever, if

the co nd enser is no t available to receive steam via the tu rbine bypass system, the rea ctor

coolant system can still be safely coo led d own using on ly Nuclear Island systems.

10.4.1.3 Evaluation

During operation , rad ioactive steam, gases, and cond ensate are present in the shells of

the ma in cond enser. The an ticipated inventory of radioa ctive contam inants during

operation and shutdown is discussed in Sections 11.1 and 11.3.

Necessary shielding a nd contro lled access for the m ain con denser are pro vided

(Section s 12.1 an d 12.3).

H ydrog en buildup durin g operation is not expected to occur due to pro visions for

continuo us evacuation o f the main con denser. During shutdown, significant hydrogen


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10.4.1.4 Tests and Inspections

Each condenser shell is to receive a field hydrostatic test before initial operation. This

test will consist of filling th e con denser shell with water a nd , at the resulting static head ,

inspecting all tube joints, accessible welds, and surfaces for visible leakage and/or

excessive deflection. Each conden ser water b ox is to receive a field hydrostatic test with

all joints and external surfaces inspected for leakage.

10.4.1.5 Instrumentation Applications

10.4.1.5.1 Hotwell Water Level

The co nd enser ho twell water level is mea sured by at lea st three level transmitters. These

transmitters provide signals to an indicator, a nnun ciator trip units, the plant computer,

and the hotwell level control system. Level is controlled by two sets of modulating

control valves. Each set consists of a normal and an emergency valve.

On e set of valves allows water to flow from th e cond ensate storag e tan k to the co nden ser

hotwell as the level drops below the setpoint. If the level increases above another

setpoint, the second set of valves located o n th e discharg e of th e cond ensate pumps

opens to allow cond ensate to be pumped back to the storag e tank.

10.4.1.5.2 Pressure

Condenser pressure is measured by gauges, pressure switches, and electronic pressuretran sducers. These instruments provide signals to ann uncia tors, trip units, the Turbin e

Con trol System, Recirculation Flow Con trol System a nd the Steam Bypass and Pressure

C l S I dd i i f i d d d d d f l d


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Con denser pressure is an input to the Reactor Recirculation System. Recirculation

pump runb ack is initiated upon the trip of a circulating water pump when con denser

pressure is higher than some site specific preset value. Runback is automatically

initiated when req uired to avoid a turbine trip on high con denser pressure.

10.4.1.5.3 Temperature

Temperature is measured in ea ch LP turbine exha ust ho od by temperature contro llers.

The con trollers modulate a contro l valve in th e water spray line pro tecting the exhaust

hoods from overheating.

Circulating water temperatures are monitored upstream and downstream of each

condenser tube bundle and are fed to the plant computer and a main control room

instrumenta tion for use during period ic con denser performan ce evaluations.

10.4.1.5.4 Leakage

Leakage of circulating water into th e cond enser shell is mon itored by the o nline

instrumentation and the process sampling system described in Subsection 9.3.2.

Con ductivity of th e cond ensate is continuo usly mon itored a t selected locations in th e

cond enser. Cond uctivity and sodium are continuo usly mon itored at th e discharge o f

the con densate pumps. High con densate cond uctivity and sodium content, which

indicate a con denser tube leak, are individually alarmed in the ma in contro l room.

10.4.2 Main Condenser Evacuation System

N d bl d f h l b h M i C d


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Power Generation Design Basis Two The MCES establishes and m aint ains a vacuum

in the con denser during po wer operation b y the use of steam jet air ejectors, and b y the

mechan ical vacuum pum p dur ing early startup.

10.4.2.2 Description

The MCES (Figure 10.4-1) consists of two 100%-capacity, double stage, steam jet air

ejector (SJAE) units (complete with interconden ser) fo r power plant o peration, a nd a

mechanical vacuum pump for use during startup. The last stage of the SJAE is a

non cond ensing stage.On e SJAE unit is nor mally in operation and the oth er is on

standby.

During th e initial phase of startup, when the d esired rate o f air and gas removal exceeds

the capa city of th e steam jet air ejectors, and nuclear steam pressure is not ad equa te to

operate th e SJAE units, the mecha nical vacuum pump establishes a vacuum in the ma in

cond enser and other parts of the p ower cycle. The d ischarge from the vacuum pump isthen routed to th e Turbine B uilding compa rtment exhaust system, since there is then

little or no effluent rad ioactivity present. Rad iation d etectors in th e Turbine B uilding

compartm ent exhaust system and plant vent alarm in th e main contro l room if

abn orma l radioa ctivity is detected ( Section 7.6). Rad iation mo nitors are provided on

the m ain steamlines which trip th e vacuum pum p if abn orma l radioa ctivity is detected

in the steam being supplied to th e cond enser.

The SJAEs are placed in service to remove the gases from the main condenser after a

pressure of about 0.034 to 0.051 MPa absolute is established in the main condenser by

the m echanical vacuum pump and when sufficient n uclear steam pressure is available.


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operation of the m echanical vacuum pumps to ensure the flammable limit of hydrogen

will not be rea ched.

The MCES has no safety-related function (Section 3.2) and, thus, failure of the system

will no t comprom ise any safet y-related system or compon ent and will no t prevent safe

reactor shutdown.

Should th e system fa il completely, a g rad ual reduction in con denser vacuum wouldresult from the b uildup of non cond ensable gases. This reduction in vacuum would first

cause a lowering of turb ine cycle efficiency due to the increase in turbine exhaust

pressure. If the MCES remained inoperab le, conden ser pressure would then reach th e

turbine trip setpoint an d a turbine trip would result. The loss of cond enser vacuum

inciden t is discussed in Subsection 15.2.5.

10.4.2.4 Tests and Inspections

Testing a nd inspection o f the system is performed prior to plant o peration in

accorda nce with applicable codes and standard s.

Com ponen ts of the system are continuo usly mon itored durin g operation to ensure

satisfactory performance. Periodic inservice tests and inspections of the evacuation

system are performed in conjunction with the scheduled ma intenan ce outages.

10.4.2.5 Instrumentation ApplicationsLocal an d rem ote ind icating devices for such param eters as pressure, temperature, and

flow indicators are provided a s req uired for m onitor ing the system opera tion. Dilution


49/86

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temperature, th e switch activates an an nuciator in the ma in contro l room . The vacuum

pump exha ust stream is discharg ed to the Turbine B uilding compartm ent exha ust

system, which pro vides for ra diation mon itoring o f th e system effluents prior to their

release to the m onitor ed vent stack and the atmo sphere.

The vacuum pump is tripped and its discharge valve is closed upon receiving a main

steam high-high rad iation signal.

10.4.3 Turbine Gland Sealing System

The Turbine Gland Sealing System (TGSS) prevents the escape of radioactive steam

from the turb ine shaft/casing pen etrations an d valve stems and prevents air inleakage

through subatmospheric turbine glands.



The TG SS does not serve or support any safety functio n and has no safety design b ases.


Power Generation Design Basis OneThe TG SS is designed to pr event a tmo spheric air

leakage into the turbine casings and to prevent rad ioactive steam leakage o ut of th e

casings of the turbine-generato r.

Power Generation Design Basis TwoThe TG SS returns the con den sed steam to th e

cond enser and exhausts the n onco nden sable gases, via the Turbine Building


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seals operate aga inst vacuum, the sealing steam either is drawn into the casing or leaks

outward to a vent a nnulus. At all gland seals, the vent an nulus is maintained at a slight

vacuum a nd also receives air in-leakage fro m the outside. From each vent ann ulus, the

air-steam m ixture is dra wn to the glan d steam con denser.

The seal steam header pressure is regulated automatically by a pressure controller.

During startup an d low load operation , the seal steam is supplied from th e main steam

line or a uxiliary steam hea der . Above approxima tely 50% load , however, sealing steamis nor mally provided from the h eater d rain tan k vent h eader. At all loads, gland sealing

can be a chieved using auxiliary steam so that plan t power operation can be m aintained

without appreciable radioactivity releases even if highly abnormal levels of radioactive

contam inants are present in the process steam, du e to una nticipated fuel failure in the

reactor.

The outer portion of a ll glands of the turbin e and main steam valves is conn ected to th e

gland steam con denser, which is mainta ined at a slight vacuum by the exhauster blower.

During plan t operation , the gland steam cond enser and on e of the two installed 100%

capacity motor-driven blowers are in operat ion . The exhauster blower to th e Turbin e

Building co mpartm ent exha ust system effluent stream is continuo usly mon itored pr ior

to being d ischarged . The glan d steam cond enser is cooled by main con den sate flow.

10.4.3.3 Evaluation

The TG SS is designed to prevent leakage of ra dioactive steam from the m ain turb ineshaft g land s and the valve stems. The h igh-pressure tu rbine shaft seals must

accommo date a rang e of turbine shell pressure from full vacuum to a pproximately


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10.4.3.5 Instrumentation Application

10.4.3.5.1 Gland Steam Condenser Exhausters

10.4.3.5.1.1 Pressure

G land steam con denser exhauster suction pressure is continuo usly monitored and

reported to the main con trol room and plant computer. A low vacuum signa l actuates

a main control room annun ciator.

10.4.3.5.1.2 Level

Water levels in the glan d steam cond enser drain leg a re mon itored a nd makeup is

add ed a s required to m aintain loop seal integrity. Abno rmal levels are an nunciated in

the main control room.

10.4.3.5.1.3 Effluent Monitoring

The TGSS effluents are first monitored by a system-dedicated continuous radiation

mon itor installed on the glan d steam conden ser exhauster blower discharge. H igh

mon itor reading s are alarmed in the m ain con trol room . The system effluents are then

discharg ed to the Turbine B uilding compartm ent exha ust system an d th e plant vent

stack, where furth er effluent rad iation mo nitoring is performed . (See Subsection

10.4.10.1 for CO L license infor mation pertaining to th e rad iological ana lysis of the

TG SS effluen ts.)

10.4.3.5.2 Sealing Steam Header

S li t h d i it d d t d t th i t l d


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Power Generation Design Basis OneThe TBS h as the capacity to bypass at lea st 33%

of the rated main steam flow to the main condenser.

Power Generation Design Basis TwoThe TBS is designed to b ypass steam to the m ain

condenser during plant startup and to permit a normal man ual cooldown of the

Reactor Co olant System from a hot shutdo wn cond ition to a po int consistent with

initiation of Residual H eat Removal System o peration.

Power Generation Design Basis ThreeThe TBS is designed, in conjunction with the

reacto r systems, to provide for a 40% electrical step-load reduction withou t reacto r trip.

The systems will also a llow a tu rbine trip b ut witho ut lifting the ma in steam safety valves.


10.4.4.2.1 General Description

The TBS shown in Figure 10.3-1 (Main Steam System), consists of a three-valve chest

that is conn ected to th e main steamlines upstream o f the turb ine stop valves, and of

three d ump lines that separately conn ect each bypass valve outlet to one cond enser

shell. The system is designed to b ypass at least 33% of the rated main steam flo w directly

to the co nd enser. The system a nd its componen ts are shown in Figures 10.4-9 and 10.4-

10.

The TBS, in co mbin ation with the reactor systems, provides the capab ility to shed 40%

of th e T-G rated load without reactor trip an d without th e operation of safety/relief


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10.4.4.2.3 System Operation

The turbine bypass valves are opened by redundant signals received from the Steam

Bypass and Pressure Control System whenever the actual steam pressure exceeds the

preset steam pressure by a small margin. This occurs when the amount of steam

generated by the reactor cann ot b e entirely used b y the turbine. This bypass dema nd

signal causes fluid pressure to be a pplied to the operating cylinder, which o pens the first

of the ind ividua l valves. As the bypass demand increa ses, ad ditiona l bypass valves are

opened , dum ping th e steam to the con denser. The bypass valves are equipped with fa st

acting servo valves to allow rapid opening of bypass valves upon turbine trip or

generator load rejection.

The bypass valves auto mat ically trip closed when ever the vacuum in the ma in con den ser

falls below a preset value. The bypass valves are also closed o n lo ss of electrical po wer or

hydra ulic system pressure. The bypass valve hydrau lic accumula tors have the capability

to stroke the valves at least three times should the hydraulic power unit fail.

When the rea ctor is operating in th e auto matic load -following mod e, a 10% load

reduction can b e accomm od ated without open ing th e bypass valves, an d a 25% load

reduction can b e accomm od ated with momen tary opening of th e bypass valves. These

load ch ang es are accomplished b y chan ge in reactor recirculating flow without an y

control rod motion.

When the plan t is at zero po wer, hot stand by or initial coold own, th e system is operatedman ually by the control roo m opera tor or b y the plant a utoma tion system. The

measured reactor pressure is then compar ed ag ainst, and regulated to , the pressure set


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The effects of a ma lfunctio n o f the turbin e bypass system valves and the ef fects of such

a failure on other systems and co mpon ents are evaluated in Cha pter 15.

10.4.4.4 Inspection and Testing Requirements

Befo re the TBS is placed in service, all turbin e bypass valves are t ested for operability.

The steamlines are hydrostatically tested to confirm leaktightness. Pipe weld joints are

inspected by rad iograph y per ASME III , Class 2 requirem ents upstream an d ANSI B31.1

do wnstream of the valve chest. The b ypass valves may be tested while th e un it is in

operation . Period ic inspections are performed on a rota ting ba sis within a preventive

maintenance program in accordance with manufacturers recommendations.

10.4.4.5 Instrumentation Applications

Main steam pressure is redunda ntly measured in the rea ctor d ome by six electronic

pressure tran smitters. Und er no rmal con ditions, a validated narro w range pressure

signal will be used by the Steam Bypass an d Pressure Co ntrol System (SB&PC ). If o ne of

the signals fails, an ann unciator will be activated but th e bypass control an d/or reactor

pressure regulation will be un affected.

Input to the system also includes load dema nd and load r eference signals from the

turb ine speed load con trol system. The SB&PC System uses these three signa ls to

position th e turbine cont rol valves, the bypass valves, an d, ind irectly the rea ctor in ternal

recirculation pump speed. A complete description of the control system is included inChapter 7.

104 5 Circulating Water System


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The C irculating Water System (Figure 10.4-3) con sists of the following compon ents: (1)

screen ho use and intake screens, pumps, (2) cond enser water bo xes and piping and

valves, (3) tube side of the ma in con denser, (4) water bo x fill and drain subsystem, an d

(5) related support facilities such as for system water treatment, inventory blowdown

and general maintenance.

The po wer cycle heat sink is designed to ma intain th e temperature o f the water en tering

the CWS within th e rang e of 0C to 37.78C. The CWS is designed to deliver water to

the main con denser within a tempera ture range o f 4.45C to 37.78C. The 4.45C

minimum tempera ture is mainta ined, when n eeded, by warm water recirculation.

The cooling water is circulated by at least three fixed speed motor-driven pumps.

The pumps are arranged in parallel and discharge into a comm on h eader. The

discharg e of each pump is fitted with a butterfly valve. This arrang ement permits

isolation and maintenance of any one pump while the others remain in operation.

The C WS and cond enser is designed to permit isolation of ea ch set of the three series

conn ected tube bund les to permit repair of leaks and cleaning of water bo xes while

operating at reduced power.

The CWS includes water b ox vents to h elp fill the cond enser water bo xes during startup

and removes accumulated air and other ga ses from th e water boxes during n orma l


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The circulating water pumps are tripped and the pum p an d co nden ser isolation valves

are closed in the event of a system isolation signal from the co nd enser pit high-high

level switches. A conden ser pit high level alarm is provided in the con tro l room. The pit

water level trip is set high enoug h to prevent ina dvertent plan t trips from un related

failures, such as a sump o verflow.

Drain ing o f an y set of series conn ected con denser water bo xes is initiated by closing th e

associated con denser isolation valves and opening th e drain con nection an d water boxvent valve. When the suction standpipe of th e con denser dr ain pum p is filled, the pump

is manua lly started . A low level switch is provided in th e stand pipe, on the suction side

of th e dra in pump. This switch will autom atically stop the pump in the event o f low

water level in the standpipe to protect the pump from excessive cavitation.

10.4.5.3 Evaluation

The CWS is not a safet y-related system; however, a flooding a na lysis of th e Turbin eBuilding is performed o n th e CWS, postulating a co mplete rupture of a single

expansion joint. The analysis assumes that the flow into the condenser pit comes from

both the upstream an d d ownstream side o f the b reak and , for con servatism, it assumes

tha t on e system isolat ion valve do es not fu lly close.

Based on the above conservative assumptions, the CWS and related facilities are

designed such th at the selected com bination of plant physical arrangem ent an d system

protective features ensures that all credible potential circulating water spills inside theTurbine B uilding rema in confin ed inside the co nd enser pit. Further, plan t safety is

ensured in case of multiple CWS failures or other negligible probability CWS related


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10.4.5.7 Portions of the CWS Outside of Scope of ABWR Standard Plant

The po rtion outside the ABWR Stand ard Plan t includes:

screen h ouse and intake screens; pumps and pump d ischarge valves; an d

related support facilities such as makeup water, system water treatment,

inventory blowdown, and general maintenance.

10.4.5.7.1 Safety Design Basis (Interface Requirements)

None

10.4.5.7.2 Power Generation Design Basis (Interface Requirements)

The C OL applicant shall provide the following system d esign featur es and a dd itional

information which are site dependent;

(1) Compatible design as described in Subsection 10.4.5.2.

(2) Evaluation per Subsection 10.4.5.2.

(3) Tests and Inspections per Subsection 10.4.5.4.

(4) Instrument applications per Subsection 10.4.5.5.

(5) Flood protection per Subsection 10.4.5.6.

10.4.5.8 Power Cycle Heat Sink (Conceptual Design)


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(3) Tests and inspections per Subsection 10.4.5.4.

(4) Instrument applications per Subsection 10.4.5.5.

(5) Flood protection per Subsection 10.4.5.6.

(6) The power cycle heat sink must provide for coo ling of Turbine Service Water

System while the plant is operating on the Co mbustion Turbine G enerato r in

the a bsence of offsite power.

10.4.6 Condensate Purification System

The Co nd ensate Purification System (C PS) purifies and treats the cond ensate as

required to ma intain rea ctor feedwater purity, using filtration to remove suspend ed

solids, including corro sion prod ucts, ion exchang e to remove dissolved solids from

cond enser leakage and o ther impurities, and water treatm ent ad ditions to minimize

corrosion/erosion prod uct releases in th e po wer cycle.



The CPS does not serve or support any safety function and has no safety design bases.


Power Generation Design Basis OneThe CP S cont inuo usly remo ves dissolved an d

suspend ed solids from the con densate to ma intain reactor feedwater q uality.


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Power Generation Design Basis SixThe CP S maintains the cond ensate storag e tank

water qua lity as required fo r cond ensate makeup and miscellaneo us cond ensate supply

services.

Power Generation Design Basis SevenThe CPS flow con tro llers an d sequences will be

at least dual redun dan t an d th e vessel flow signals and b ypass arran ged such that the

cond ensate system flow will be uninterrupted even in th e presence of a single failure.

10.4.6.2 System Description


The C on den sate Pur ification System (Figure 10.4-4) con sists of a t least three high

efficiency filters arran ged in pa rallel and opera ted in con junction with a no rmally

closed filter bypass. The CPS also includes at least six bead resin, mixed bed ion

exchange demineralizer vessels arranged in parallel with, normally at least five in

operation and one in standby. A strainer is installed do wnstream o f each d emineralizervessel to preclude gross resin leakage into the power cycle in ca se of vessel und erdrain

failure, and to ca tch resin fine leakage as much as possible. The d esign b asis for the CPS

system will be to ach ieve the water q uality effluent cond itions defined in the G E water

qua lity specification. The C PS compo nents are located in the Turbine B uilding.

Pro visions are included to permit air scrub cleaning and replacement of th e ion

excha nge resin. Each o f the demineralizer vessels ha s fail-open inlet and outlet isolat ion

valves which are remotely contr olled from the local CP S control pan el.

A dem inera lizer system b ypass valve is also provided which is man ually or automat ically


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operation full load steady-state design flowrate is 2.52L/s of bed. Maximum flowrates

are 3.15 an d 3.79L/s for steady state a nd transient operatio n, respectively. The n ominal

bed dep th is 102 cm.

10.4.6.2.3 System Operation

The CPS is continuously operated to maintain feedwater purity levels.

Full condensate flow is passed through at least three filters and at least five of the sixdem inera lizers, which are piped in para llel. The last deminera lizer is on stan dby or is in

the pro cess of being cleaned , emptied o r refilled. The service run of each d emineralizer

is terminated by either high differential pressure acro ss the vessel or high effluent

cond uctivity or sodium con tent. Alarms for each o f these parameters are provided on

the local control panel and the main control room.

The service run for each filter is terminated by high differential pressure across the

filter. Alarms are provided on the local con trol pan el.

The local contr ol panel is equipped with the a ppropriate instruments and contro ls to

allow the operators to perform the fo llowing operation s:

(1) Remove a saturated filter from service, temporarily allowing some condensate

filter bypass. Clean up the isolated filter by backwashing and place it back in

operation.

(2) Remove an exhausted demineralizer from service and replace it with a standby

unit


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when the required minimum rinse has been completed and normal clean bed

conductivity is obtained.

A filter with h igh d ifferen tial pressure is remo ved fr om service and the filter system

bypass valve is opened to maintain condensate flow. The filter is backwashed, refilled

an d return ed to service. The filter system bypass valve is then closed.

Throug h no rmal cond ensate makeup and reject, the conden sate storag e tank water

inventory is processed th rough the C PS, and tank water qua lity is mainta ined as

required for con densate ma keup to th e cycle and miscellaneo us cond ensate supply

services.

The condensate purification and related support system wastes are processed by the

radwaste system, as described in Chapter 11.

10.4.6.3 EvaluationThe CPS does not serve or support any safety function and has no safety design bases.

The Con densate Purification System removes cond ensate system corrosion prod ucts,

and

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