ML20040F063

SEP Review of Safe Shutdown Sys for Yankee Rowe Nuclear Power Plant, Revision 1

ML20040F063
Person / Time
Site:	Yankee Rowe
Issue date:	01/31/1982
From:	FRANKLIN INSTITUTE
To:
Shared Package
ML20040F054	List: ML20040F053 ML20040F063
References
TASK-05-10.B, TASK-05-11.B, TASK-07-03, TASK-5-10.B, TASK-5-11.B, TASK-7-3, TASK-RR TER-C5247-310-R01, TER-C5247-310-R1, TER-C5257-310, TER-C5257-310-R01, TER-C5257-310-R1, NUDOCS 8202080273
Download: ML20040F063 (90)

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SEP Review of Safe Shutdown Syrrens for the Yankee Bowe-Nuclear Power Plant

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(Revision 1)

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TER-C5257-310 9

CONTENTS Section Page 1

INTRODUCTION...................................................B-1 2

D I S C US S ION..................................................... B-6 2.1 Normal Plant Shutdown and Cooldown........................B-6 2.2 Shutdown and Cooldown with Loss of Of f site Power..........B-8 3

CONFORMANCE WITH BRANCH TECHNICAL POSITION 5-1 FUNCTIONAL REQUIREMENTS........................................B-10 3.1 Ba c kg ro und................................................ B-10 3.2 Functional Requirements...................................B-19 3.3 Safe Shutdown Instrumentation.............................B-56 4

SPECIFIC RESIDUAL HEAT REMOVAL AND OTHER REQUIREMENTS OF BRANCH TECHNICAL POSITION 5-1...............................B-60 4.1 Residual Heat Removal System Isolation Requirements.......B-60 4.2 Pressure Relief Requirements..............................B-62 4.3 Pump Protection Requirements..............................B-68 4.4 Test Requirements.........................................B-69 4.5 Op era tional Pro c edures.................................... B-7 0 4.6 Auxiliary Feedwater Supply................................B-70 5

RESOLUTION OF SYSTEMATIC EVALUATION PROGRAM TOPICS.............B-72 i

-5.1 Topic V-10.3 RHR System Reliability......................B-72

5. 2 Topic V-ll.A Requirements for Isolation of High and Low Pressure Systems and i

Topic V-ll.B RHR Interlock Requirements..................B 74 5.3 Topic VII-3 Systems Required for Safe Shutdown...........B-76 5.4 Topic X Auxiliary Feed System............................B-77 6

REFERENCES.....................................................B-78 i

B-iii

TER-C3257-310 1.

INTRCDUCTICN The Systematic Evaluaticn Program (SEP) review of the " safe shutdown" subject encompassed all or parts of the following SEP tcpics, which are among those identified in the November 25, 1977 NRC Cffice of Nuclear ' Reactor Regu-lation document entitled "Repcet on the Systematic Evaluation of Operating Tac ilities":

1.

Residual Heat Remeval System Reliability (Topic V-10.3) 2.

Requirements for Isolation of Eigh and Low Pressure Systems (Topic V-11. A) 3.

Residual Heat Remeval Interlock Requirements (Tepic V-11.3) 4.

Systems Required for Safe Shutdown (Tepic VII-3)

I-5.

Statien Service and Cooling Water Systems (Tepic IX-3) 6.

Auxiliary Feedwate: System (Tepic X).

The review was primarily performed during an ensite visit by a team of SEP personnel. This onsite effcet, which was performed f:cm June 13 to June 16, 1978, af ferded the team the cppcetunity to cbtain current information and to examine the applicable equipment and procedures, and it also gave the licensee (Yankee Atemic Elect:ic Cc=pany) the cppcetunity to previde input into the review.

The review included specific system and equipeent requirements fer remaining in a hot standby conditien (defined as the reactor suberitical with T

greater than or equal to 330 F) and for proceeding to a cold AVE

[

l shutdown condition (defined as reactor coolant temperature less than or equal to 200 F).

The review for transition from reactor operation to 1

1

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hot standby considered the requirement for the capability to perform this operation from outside the control room. The review was augmented as necessary to assure resolution of the applicable topics, except as noted i

below:

i Topic V-11.A (Requirements for Isolation of High and Low Pressure l

Systems) was examined only for application to the residual heat removal (RHR) 1 system. Other high pressure / low pressure interfaces were not investigated in j

this review.

i B-1 l

9 TIR-C5257-310 Tepic VII-3 (Systems Required for Safe Shutdown) was cong.eted except for determinatien of design adequacy of the system.

Tepic IX-3 (Station Service and Cooling Water Systems) was only reviewed to consider redundancy and seismic and quality classificatien of cooling water systems that are vital to the performance of safe shutdewn system ecmponents.

Topic X was reviewed only to address design adequacy for heat removal.

Other aspects are considered as part of the design basis event review cc under implementation of the TMI Action Plan.

The criteria applied to the saf e shutdown rystems and cceponents in this review are taken from the Standard Review Plan (SRP) 5.4.7, " Residual Heat Remeval (RER) System"; Branch Technical Position RSS f-1, Revisien 1, "0esign Requirements of the Residual Heat Rameval System"; and Regulatcry Guide 1.139,

" Guidance for Residual Heat Removal." These documents represent current staff criteria and are used in the review of f acilities being processed for cperating licenses. This.ccmparison of the existing rystems with current licensing criteria led naturally to at least a partial censideration of design criteria that will be pertinent to SIP Tepic III-1, "Classifi' ation cf c

Structures, Ccmpenents and Systems (Seismit and Ouality)." This repcrt will also be reviewed fer its applicatien to the resolutien Of cther scpics.

As noted above, the six tcpics were examined while possible interactions l

with other tcpics, systems, and cempenents not directly related te safe l

i shutdown were neglected. For example, Tepirs II-3.3 (Flcoding Petantial and Protecticn Requirements), ::-3.C (Saf ety-Related Water Supply), III-4. C (Internally Generated Missiles), III-5. A (Iff ects of Pipe 3reak en Structures, Systems and Ccmpenents *nside Centainment), :::-6 (Seismic Design Considerations), III-10.A (Thermal Cvericad Prctecticn for Meters of j

Meter-Cperated valves), :::-11 (Cempensat :ntegrity), 'III-12 (Invircnmental Qualification of Saf ety-Related Iquipment), and 7-1 (Cempliance with Codes and Stand ards ) could be af f ected by the results of the saf e shutdewn review ce t

could aff ect the safety cf the systems that were reviewed. These eff ects will be reviewed latar. Further, this review did not ecver in any significant A

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o TER-C5 257-310 detail either the reactor pectection system or the electrical power distribution, both of which will also be reviewed later.

The staff considers that the ultimate decision concerning the saf ety of any of the SEP facilities is based upon the ability of the f acility to withstand the SEP design basis events (DBEs). The SEP topics provide a major input to the OBE review, fecm the standpcint of assessing both the probability and the consequences of the event. As examples, the safe shutdown topics pertaining to,the, listed DBEs are provided in Table 3.1 (the extent of applicability will be determined during the plant-specific review).

00=pletien of the safe shutdown topic review (limited in scope as noted abcve), as documented in the attached report, significantly centributes to an assessment of the existing safety =argins.

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TIR-C5257-310 Table B.1 Dd. PACT UPCN PRCBABILITY MPIC DBE GRCCP OR CONSECCENCIS OF OBE V-10.3 VII (Spectrum of Less-of-Consequences Coolant Accidents)

V-11.A VII (Defined above)

Probability V-11.3 VII (Defined above)

Probability VII-3 All (Defined as a generic topic)

Consequences IX-3 III (Steam Line Break Inside Consequences Centainment)

(Steam Line Break Outside Containment)

IV (Less of AC Pcwer to Station Consequences Auxiliary)

(Ioss of all AC Power)

V (Less of Forced Coolant Flow)

Probability (Primary Pump Tetor Sei:ure)

(Primary Pump Shaft Break) v!: (Defined above)

Consequences X

II

(*. css of External " cad)

Consequences (Turbine Trip)

(Icss of Condenser vacuum)

(Steam Pressure Regulater (closed))

(: ass of Feedwater Ficw)

(Feedwater System Pipe 3reak)

( efined above)

Consequences 1

IV (Oefined abcve)

Consequences i

V (Defined above)

Consequences v!:

(Oefined above)

Ccnsequences l

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TER-C5257-310 Pici'no System Passive Failures The NRC staff normally postulates piping system passive failures as (1) accident-initiating events in acccedance with staff positions on piping failures inside and cutside contai. ment, (2) system leaks during long-term coolant cecirculatien following a !.CCA, and (3) failures resulting f:cm hazards such as earthquakes and ternado missiles. In this evaluation, certain piping system passive failures have been assumed ceyond those ncrmally postulated by the staff, e.g., the catastrophic failure of moderate energy systems. These assumptions were made to demonstrate safe shutdown system redundancy in the event of ecmplete failures of.hese systems and to f acilitate future SEP reviews of C3Es and other tcpics that will use the safe shutdown evaluation as a scurce of data for the SEP facilities. 3RP 5.4.7 and BTP RSB 5-1 do net require the assumptions of piping system passive failures.

Credit for Ceeratinc ?rocedures For the safe shutdown evaluatien, tha staff may give credit for facility eperating procedures as alternate means of meeting regulatery. guidelines.

O.ose procedural requirements identified as essential for acceptance of an SEP tepic en CBIs will be carried through the review process and considered in the integrated assessment cf the facility. At that time, the staf f will decide wnich precedures are so i=pertant that an administ:stive method must be estaclished to ensure that, in the future, these cperating procedures are not changed without appropriate consideratien of their impcetance to the 3EP tcpic evaluatien.

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TER-C5257-310 2.

DISCOSSICN 2.1 Normal Plant Shutdewn and Cooldown A normal shutdown from full pcwer a het standby is acecaplished with the use of cperating procedure CP-2104, " Scheduled Plant Shutdown to Eot Standby. " The shutdewn f:cm pcwer is accomplished by reducing the generator lead using the tu:bine centrol system and following with centrol red insertion The lead redu' t.icrt.is performed at a rate of 8 We per 5 to control T c

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minutes, and changes in main coolant average temperature are cont:olled at a rate of 2*F per 5 minutes. The reactor is borated using the charging pumps to the amount necessary to maintain the cont:ol rod bank above the low insertion limit and ensure that the axial flux difference will remain within its target band.

I The fi:st main feedwater pump and condensate pump a:e removed f:cm service when the generater lead has been reduced to less than 140 Wo.

When the generator' lead has been reduced to less than 50 We, the second main feedwater pump and condensate pump are removed f cm service. The power reduction is centinued using the remaining cperating boiler feed pump to provide feed to de steam generators. When the lead on the generater has decreased to less than 30 MWe, statien service leads are transfer:ed to tne auxiliary ::ansformers fed f:cm the effsite power supply and condensate recirculation is established back to the condenser het well. Manual control of the turbine bypass is taken when the generater lead is : educed to less can 15 se.

"he turbine is t:ipped just before the generater load reaches 3 We.

Normally, the plant can be maintained in a hot standby conditien (main coolant average temperature at 514

• F, 2000 psig) by using main coolant pump heat, decay heat, and discharging steam to the main steam header.

During the plant shutdewn to het standby, a cont:cl :cd group :emains withdrawn to a height sufficient to provide a reactivity worth of it for emergency shutdown capability. If for any :eason.a centrol :od g: cup cannot be withdrawn to previde a reactivity worth of it, then the main coolant system is berated to 5% t.k/k shutdcwn margin. Prior te preceeding :o het shutdcwn

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A TIR-C3257-310 and ' cold shutdown, the =ain coolant system is berated to the 54 Ak/k shutdown margin. The main coolant system is borated using the charging and volume centrol system. The charging pumps take sucticn from the beric acid mixing and storage tank.

If any main coolant loops are isolated, they too are borated to the shutdcwn margin.

The plant cooldewn is limited to 50*F per hour, and cooling is accceplished by continuing the bypass of steam to the main condenser. At least two main ecolant locps are tied to the reacter vessel until the shut-dcwn cooling system is in operation. Pressuricer level is now manually centrc11ed using the charging pumps to provide =akeup fer centraction caused by the cooldown of main coolant system water. Pressuricer temperature and pressure are centrolled to maintain the reacter vessel within nil dcctility transition temperature range.

When the cooldown from hot standby is initiated, all main coolant pumps may be in operation. At 370 F, main coolant pump operation is 0

limited to two pumps. When main coolant temperature is between 300 F and 330*F and pressure is less than 300 psig shutdown cooling is initi-ated.

If the main coolant system is to be depressurized, then the remaining main coolant pumps are secured.

Pressurizer temperature and and pressure reduction is performed by charging pump flow through the auxiliary spray line to the pressurizer spray, while simultaneously draining to the low pressure surge tank. When the main coolant system temperature reaches 200 F, the charging rate is increased to the main coolant system in order to fill the pressurizer. When pressurizer tem-l perature reaches 200 F, the pressurizer vent is opened to depressurize the main coolant system.

Shutdown cooling continues until the main l

coolant system reaches about 140 F, where it is maintained by the shut-down cooling system, unich is cooled by the service water system. The service water system takes cold water from the river, circulates it through the component cooling system heat exchangers and returns the warmer water to the river. Thus, heat is transferred from the main coolant system to the river to accomplish cooldown and decay heat removal.

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TG-<5257-310 2.2 Shutdewn and Cooldown with ! css of of fsite ?cwer Cperating Procedure "'. css of A.C. Supply" defines the action to be taken following a total less of ac power to pcovide emergency electrical power to vital equipment.

Folicwing a loss of effsite pcwer and turbine trip, the main conden:tr circulating water pumps cannet be pcwered f:cm onsite sources. With the loss of ci:culating water pu=ps, main cendenser vacuum cannot be maintained and the main condense: becemes unavailable fer heat removal. With de 1 ss of normal heat sink, the main steam safety valves will lif t to vent steam to at:ncspnere. The operator is directed to verify : losing of the steam dump valve en icss of cendenser vacuum and automatic sta: ting of the three emergency powe: diesel generators. In addition, the operater is di:ected to per form the necessary electrical switching to remove cennections to the offsite power lines and to start the emergency boiler feed pump and commence feeding the steam generators.

The steam supply valve to the large hogger is opened and set to maintain an inlet steam pressure of 300 psig. Electrical power is restored to the 480-V buses, and pressurizer heaters Nos. 5 through 8 are energized to restore main coolant system pressure control. The oper-ator establishes a minimum of 200 psig overpressure on the main coolant sys-tem.

A service water pump and component cooling water pump are then started to supply plant equipment cooling requirements.

Cpe: sting P:ccedure "icss of :::ndenser vacuum" delineates the acti:n to be taken :.f a icss cf==ndenser vacuum occurs while the plant is Operating at pcwer. One of the immediate actions is to initiate maximum feed and bleed and to inc: ease i=w pressure surge tank cocling, if : equi:ed.

Satsequent cpera:Or action is to line up the f:ll: wing equipment : p:cvide.ain : clan: hea:

remeval to centrol tempe:ature as necessary:

a.

at=cspheric steam dump b.

hogge: air ejectiens c.

steam drains to at:csphere d.

th::::le line steam drains to the auxilia:y teile tiewdewn tans.

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TIR-C3257-310 v.

A I-At this point, the plant's essential egaipment is being supplied through the cperation of the emergency diesel generater. Faacter decay heat is

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transferred to the steam generators and dissipated by lifting of the main

4 steam safety valves and operaticn of varicus other vent paths.

Operating Procedure " Plant Cooldown frem Ect Standby" delibeates the steps required fer a plant cooldewn with or without the main condenser in service. The cperater is directed to do the following when the main condenser 1

is not available:

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o berate the main coolant system to de shutdevn margin i

o initiate maximum feed with supplemental icw pressure surge tank t

cooling adjust the atmospheric steam dump valve to achieve the desired o

cooldewn rate but not greater than 50*F/h t

remove the emergency core cooling system frem service _when the main o

j coolant system pressure is less than 1000 psig o

initiate the shutdown cooling water system when the main coolant system pressure is less than 300 psig and temperature is between 300 and 330'F.

Cooling wi.h the shutdown cooling system is then acecmplished in the same manner as was discussed in Secticn 2.1.

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3 ? CONitRMANCE WITS 3RANCE HNICAI.,JCSIT CN 5-1 Fi:NCOIONAI SECOIREINTS

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The design shall be sNch that.the reactor can be taken f:cm acemal operat.ing conditions. to colg thu:downE using only safe 5 -grade 7

, systems. These systems shall sacisfy General resign Criteria 1 h,

~ through 5.

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The system (s)'shal1~ have suitable redundancy in tempenents and features, and sui:able-interconnections, leak detection, and isolation capabilities to assure that fee ensite elect:ical pcs.er system cperation (assuming offsite power is not available) 'and for I

of fsite electrical power system cperatica (assuming onsite power is I

not available) the' system functicn can be acccmplished assuming a j

single failure.,

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c 3.sTha system (s). shall be capable of being operated f:cm theicentrol

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retri with ef etyr only onsite or only offsite power a-railable with an f-assy..i,*d single f ailure.

In demonstrating that the system can perfers its junction assuming'a single fa' limited operate; action

.j cutside ef the centcol roca woul'

.sidered accepeatle if suitably justified.

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The system (s) shall be capable of bringing the reacter to,a cold

( shutdown condition,* with only of fsite er casite poday' available,

'Within a reasonable period of ti=e following shutdown, assu:ning tha cst limiting single failu:e.

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Cempliance of ' the Tankee ?cwe safe shutdewn systems with theses criteria w

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The 3TP 5-1 :equirements are stated with :espect to plant shutdown and l

cocidewn with,cnly effsite er only ensite pcwer available. The staff I

- tvaluat'ed the' plant's acility to ccnduct a shutdewn with caly of fsite power s i.

available and datermined that the "enly onsite pcwer availacle" case is more Li x

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"? ccesses involved in cooldewn are heat :emoval, depressuri:ation, flow circulatien, and :eactivity cent:ol. The cold shutdown conditien, as described in'the Standard Technical Specifications, refers to a suocritical i

eactc: Eith a :dacte. coola'nt. temperature no greater than 200* F.

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limiting. The plant elect:ical system is sufficiently versatile to allow energiring of all necessary equipment frem only effsite pcwer. Therefore, the

r staff concentrated its evaluation of the Yankee Rowe safe shutdewn systems to g

shutdcwn fo11cwing a 1 css of of fsite power.

4 A *saf ety-grade" system is defined, in the NUREG-0138 (11 discussion of issue No.1, as one which is designed to seismic categcry (Regulatory Guide 1.29) Quality Gecup C cr better (3egulatcry Guide 1.26) and is operated by elect:ical instruments and centrols that meet Institute of Electrical and b

Electronics Engineers criteria for Nuclear Power Plant Prctection Systems (IIII Std 279-1971). Yankee Powe received its Full Term cperating License C

en June 23, 1961 price to the issuance of Regulatory Guides 1.26 and 1.29 (as Saf ety' Giides 26 and 29 cn Marca 23 and June 7,1972, respectively). Also, f

the proposed EIZ Std 279, dated August 30, 1964, was not used in the design o'f the f acility. Therefore, for this evaluation, systems which should be "saf ety-grade" are the shutdown systems classified in Tacle 3.1 and those ta,bulated in the minimum list of saf e shu Jewn systems that follows.

General Cesign Criteria (CDC) I through 4 (2) require that systems, structures, and compenents i=pertant to safety (1) be constructed to quality standards, and (2) be protected from the eff ects of natural phenomena (earthquaxes, etc.) and other cenditions (fires, pipe treaks, etc.). ::C 5 requires that systems i=pertant to saf ety not be shared among other nuclear pcwer units unless such sharing dces not significantly impair the performance cf system safety functions. Per Yankee acwe systems and equipment, the various aspects of GDC 1 through 5, including the systems required for safe shutdewn, will be evaluated elsewhere under several SI? topics.

In ceder to acecmplisa a plant shutdcwn and cooldcun fcilowing a loss of offsite pcwer, certain

• tasks" must be performed, such' as core decay heat removal, steam generater makeup, and cc=penent :ooling.

The staf f and i

Licensee develeped a ' minimum list" cf systems necessary to perform these tasks, considering a 1 css of of fsite ac power and the mest limiting single failure. Althougn ether systems may be used to perform shutdown and cooldown I'

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l II2-C5257-310 functions, the following list is the minimum number of systems required to fulfill the !?? MB 5-1 criteria 1..

steam relieving paths involving main steam, auxiliary steam, and heating steam systems 2.

auxiliary feedwater system 3.

water sources ' demineralized water s crage tank, primary makeup tank, and safaty intection tanx) 4, shutdown cooling system 5.

cergonent cooling system 6.

service water system 7.

pressure centrol and celief system

,8. chemical and volume centrol system 9.

control aic system 10.

emergency pcwer system 11.

instrumentation for shutdown and cooldewn.*

O.e staf f's eva.*uatien of each of these systems, with respect to the BTP 5-1 functienal requirements, is given in Secticn 3.2.

The power supplies and.

location of majer safe shutdewn ecmpenents are also previded.

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• For a list of saf e shutdewn instrumentation, see sectien 3.3.

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TABLE 3.1 CLASSIFICATION OF SHUTDOWN SYSTEMS - YANKEE ROWE 4

Quality Group Seismic Plant

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Components /Sub.aystems R.G. 1.26 Design.

R.G.I.29 Design Remarks Emergency Feedwater System l-L*

Pumps ASME III Note 2 Category I Note 2 Class 3 it

• 5 Piping from PWST/DWST ASME III Note 2 Category I Note 2 k

to pump suction Class 3 Discharge piping ASME III Note 2 Category 1 Note 2 lh Class 3 3

n In Steaam System 4

m in steam lieaders ASME III ASA B31.1 Category I Note 1 t rum ute.ma gener atot s Class 2 up to asad including time

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non-return valves, steam supply to the EFBP and af cosinect lang piping up to g

and including Llie i f r ut valve Lliat is siosmally closed or capalile ut autumatic closure i

e Huer sjency Ikal1er Feed Ptmap ASME III Mfr. Std.

Category I Note 1 Class 3 EntvP piping trum diu-ASME III ASA D31.1 Category I Note 1 clean ge of 'insesp tu sitain Class 3 teed linieu including talFP rellet es niin.tced piping l a usi A.iME III ASA D31.1 Category I thite 1 NI and leicludisig valves Class 3 s3 Mov-l uG I tietougli 1006, U

CV-1000 A, CV-I l00 A, U

(N-1200A, acid CVljo0A, up e's to valvera CV-1000, 1100, o

1200, c d 1300

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guali ty Grom:1.s Se i tan ic Plaint Plarnt g

a :i cymtwinent ufSulmyst enes R.G.

1.26 Inesign R.G.

1.29 lusign Reimar ks l

Y Main teed piping (sces ASME III AS A 1131.1 Category I Note 1

.a asial incitselisig CV-1000, cleais 2 l;El p

1100, 1200, acid 1300 up to tlie steam generators and cosmecting pipisig tap to and including Llie tirst valve E lio t.

is norsaally closed oa caguhle ut auttan.st ic closur e 13nFl* piping froin suction ASME Ill ASA 1111.1 Category I Note 1 Hefer to Tecimical

[ of gnunp to asal including Class 3 Specification 3.7.1.)

• Lise IMST and/or the l'WST asul comistecteil piping up to acid includisig the tirst valve tisat is citlier normally closed or capable of duttamatic closute blaut down h=>l1sig Syst ein Pamup ASME III Mir. Std.

Category I Note 1 Claus 3 ileat exclasesiger (2,licll side)

ASME III ASME VIII Category I Note 1 Ileat excleanger also Class 3 (1956) constructed in accordance with'the 1956 edition of (tube side)

ASHE III Stasulards of the Tutustar Class 2 Exchanger Mfr's. Asso-clatiam

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1 TADI.E 3.1 (Continued) t=~ '

$g Quality Grout >

Sei tan ic Plant Plant j j a 5' c< an gw wie n t s/Su tisy s t ew s it. G. 1.26 Ik_ sign R.G.

1.29 Design itemark a

$"4 SCS piping frama MOV-552 ASME III AS A B31.1 Category I Note 1 1.,$

througli time SCS pumip and Class 2 (1955) le and cosinected pipisig up to the first norinally closed valve or valves capalsle of auttamatic closute Cassimusient Cooling Wat er Piaupu (2)

ASME III ASHE VIII Category I Note 1 j

ta Class 3 (1956) llea t exchangers (Liaise side)

ASME III ASME VIII Category I Note 1 (shell side)

Class 3 (1956)

CCW piping and connected ASME III ASA B31.1 Category I Note 1 Notes Piping which piping up to and including Class 3 (1955) Sect.

penetrates up to comit aisseent I and 6 the outeranost con-the ilast valve'that is ta isement isolation either notonally closed og valve should be ASME cal.alele of aut<anatic III, Class 2 closute Ah, CCW surge tank ASME III ASME VIII Category I l*>te 1 Class 3 (1956) y U

CCW valves and tittimigs ASME III ASA B16.5 Category I Note 1 0

class 3 (1957) l e

TABIE 3.1 (Continued)

Otsality Groniin Seloele Plant Plant lu '

Caseg osients/Sulesyst ems H.G.

1.26 Design H.G.

1.29 Design Hemarks

' N f, $

Service Water _Syston es 8

h Ptamps (3)

ASME III Mfr. Std.

Category I Note 1 12 Class 3 9

Q SHS piping and connected ASHE III ASA D31.1 Category I Note 1 Notes Piping which g

piping up to and incitAing Clahs 3 '

penetrates contaisement a

Llie !Irct valve that is up to the outermost contairement isolation either normally closed or valve stu>uld 13e ASME III cagiatste or autannatic Class 2 closure Psesbute control

[,

Dalenold-openated ASHE III B31.1 Category I Note 1 pressurizer reliet Class 1 ASME Sec I m

valve and U16.5 Pteusurizer tellet ASME III H16.5 Category I Note 1 valve Claus 1 nain ptcusur!zer upray ASHE III til 6.5 Category I Hole 1 tiow luolatioss valve Class 1 Category I Note 1 Prebuurizer heaters N/A N/A F5iAR Sections 203 and 204 C_honical and votinae control Syst use Pinops (3)

ASME III ASME III Category I Note 1 Note: The systus !)oundary Class 2 (1956) includes connecting piping up to and inicluding the IJaw g.a essut e surge tank ASME III AStiE VIII Category I Note 1 first valve Lliat is either class 2 (1956) normally closed or capable of autumatic closure

I TAllt.E 3.1 (Cont i nued) lit e 5'

/f Qina1ity Group Sei saa ic y

Plant Plant 5

C.anoneits/ Subsystems H.G.

1.26 thesign H.G.

1.29 thmsign item ar k s S

e il Piping and valveu taan ASME III ASA 31.1 Category I Note 1 4

piump discliarge to class 2 (1955) Sect.

Cit-V-617 and Cil-V-611 1 and 6 I

Piping t sue and inclu-ASME III ASA B31.1 Category I Note 1 ding CH-V-617 and Class 1 (1955) Sect.

Cil-V-611 to Llic maist 1 and 6 coolant nyutua a

T U

l.ctdown piping frosa time ASME 111 ASA B31.1 Category 1 Note 1 inalsi coolasit syste.sn to and Class 1 (1955) Sect.

Including Llic orifice 1 and 6 la.olatiosi valves Feed and bleed laeat ASME 111 ASME VIII Category I Hole 1 excliasiger u class 1 (1956) 1.etdown piping tsun ASME Ill ASA 31.1 Category I Note 1 orifice tsulation Claus 2 (1955) Sect.

valveu to imp 1 and 6 suctions via I.PST Pipling issan untely ASHE !!!

ASA 31.1 Category I Hole 1 Notes Doration la lujection tank to Class 2 (1955) Sect.

performed by CVCS puals clean ging gwpa via 1 and 6 using borated water from Milv-540 up to anal S1 tank or HAMT including valve CS-V-630

TABl.E 3.1 (Coun t inued)

Quality Grout Sel:4a lc I

Plant P lasit.

(

H.G.

1.26 Des 19si H.G.

1.29 tieslan Husarks pp>uent s/Sulisyst esa s Piping froia CS-V-630 ASME III ASA 31.1 Category I Note 1 BAMT was fabricated to 3

to Ix>r ic acid anix tank Class 3 (1955) Sect.

ASME VIII i

t5; MOV-529 1 and 6 a3 h

}Q As CVCS valJes asid t ilt isign As alnave ASA D16.5 Category I Note 1 g

tur pipisig (1953)

J Haes ejency Power Syst un g

a Diesel generators (3)

HA Category I Note I lA* tower syst ua Category I Note 1 l

Distr ilantioni llanes, Category I mte 1 bwl tclyjemt, control Insagds, santor control l

y e.

centeru Diesel generator ASME III ASA B31.1 Category I Note 1 fuel oil systein Claus 3 l

centeol Alt Air casupt essoa s and Quall'y Note 1 Non-Selsaic Note 1 Air systosas required to abboClatt:d cajulgamesit.

G!<,up D Cat egor y twr forsa saf ety functioens (e.g., accteaulator and piping to a safety-related valve) are selanic C at egor y I.

I

~ Service Air l

Air ctanpressors Quality nato 1 Non-Selualc Hole 1 Group D Category f

Note It Plant design in f orsaa t iost is not kanowin.

Note 2: Newly installed system

d 1

7 TER-C5257-310 4

3.2 Functional Pseuirement STTJut REL:r/ING PATES Task: Removal of core decay heat and main coolant system sensible, heat by venting steam f:cm the :nain steam system directly to at:nosphere.

Discussien Immediately af ter the icss of of fsite ac power, turbine trip, and :eactor se'r am, the main steam safety valves automatically actuate to cent:o1 steam system pressure and main cociant system temperature. Ecwever, the main steam saf ety valves are not normally used at pressures 241cw their lif t pressure, l

although a lif ting lever is furnished en each valve fet manual cperation. The cocidown of the Yankee acwe main coolant system following a less of offsite ac pcwer wculd be accomplished using the atmospheric dump valve (A:v) and several other steam ficw paths. The following paragraphs will briefly describe each vent path.

The air-centro 11ed A V' vents steam f:cm any of the four 14-inch (cucside diameter (CD]) main steam lines between the vapor containment and the turhine building. The ADV vents steam *:cm a steam header pressuri:ed by manually operated 1-inch isolatien valves ":cm any cr all of the four main steam i

lines.

he piping system is arranged such that the A:V can remcve energy ":cm any or all steam generators.

• he Licensee calculated the capacity of the A V based en 775 psig saturated steam and critical flow. The mass "1cw rate cut the A0V is about 29,5CC les/h or secut 9100 Stu/sec (based on 1199 Stu/lbm hg and 28 Stu/lbm h,").

t

' Air is supplied :: the A V diaphragm f:cm either the instrument air system ce f:cm a newly installed (dedicated) N2 bottle.

"Oce staf f notes that scst of the feedwate: inside the steam generatcc is at l

l T

and the:efere an he of abcut 500 3tu/lba wculd have been =c:e

sat, l

appecpriate initially. Ecwever, even use of this enthalpy foes not account j

for :he dif'erence between the calculated and measured energy :emeval :ste of the A v.

l u

I 3 -13

. d.J Frannlin Resesich C. enter

=saaeNn a

j l

l

TIR-C5257-310 Actu'al measurements, however, indicated that the capacity of the A V is considerably less. The tests were eteducted by calculating the cocidewn rate with the ADV fully open, knowing the heatup = ate with the A V shut. The tests showed the A V able to remove cnly about 3100 Stu/sec.

Based en actual measurements of these tests, the Licensee censidered it necessary to previde another flow path for energy remov61. The flew path c:eated allows steam to pass fecm the pressuri:ed steam header, as with the ADV, th:cugh two manually operated valves (AS-V-720 and AS-V-721) and then to atmosphere through a 1-inch pipe. Both valves are normally closed.

The Licensee's calculated energy removal rate using this path is about 9661 Btu /sec. This value was calculated by assuming a steam pressure at 775 psig, critical flow from a 1-inch pipe, and a feed-water inlet of 120 F.

i t

The plant operating peccedure for a "Less of A.C. Supply," CP 3:51 (discussed in Section 21, directs the operater to start the amergency boiler feed pu=p (ESTP) and line'up steam to the large "hoglier." The la:ge and small hoggers at Yankee 3cwe are single-stage venturi-type air ejec. tors which draw from the condenser and exhaust directly :o atmosphere (unlike the main air ef ectors which exhaust to the shell side of a condenser cocied by condensate).

The heggers are ncesally used for remcving la:ge ascunts of air and gasses f:cm the condenser during startups.

(Ouring startups, steam fer the hogge:s ccmes f:cm the main steam lines.)

The hoggers Osn be used to :emove energy fren the steam generaters by cleeding steam f::s the main stem system to the hcggers via the auxiliary steam system. In tais mode of cperation, *2e sucticn valves to the main condense are shut.

Main steam is th:Otr.ed at the no::le inlets to maintain about 300 psig en the la:ge hegger and 50 psig en the small hogger. Since there is no aut matic pressu:e :egulater, as main steam p: essure d: cps during the :eacter coclant system (RCS) cocidewn, the th:cttle valve setting must be manually adjusted.

The IST? is utill:ed := pacvide feedwater to the steam generators during the less of cffsite ac pcwer and is descri:e'*, in the following section. The 4

l

.... = eewn nee. ente.n cener s -20

~.n-

TER-C5257-310 E3FP can be used to remove energy f:cm the steam generators, since the IBFP uses steam f:cm the main steam system via the auxiliary steam and heating steam systems. Steam pressure is automatically maintained at 100 psi by pressure control valve PC7-305.

The earliest time follcwing a lo'ss of offsite ac pcwer and reacter shutdewn when each component's energy release :ste equals the cere decay heat generatien rate is provided below.

Energy Removal Rate Cemeenent f3tu/h)

Time thours )

6 ADV 13.5 x 10 s10 1-in vent 42.3 x 10 so.2 6

Large hogge:

5.50 x 10

>36 0

Small hogger 1.12 x 10

>36 IBFP 2.27 x 10

>36 Staff sceping calculatiens assumed that steam generater pressure remained at 935 psig (lowest main steam safety valve setpoint) until the ecmpenent energy removal rate equals the decay heat generatien : ate.

The time calculated :epresents the appecximate time when (1) plant cooldown ec=mences if the ccepenent is used and (2) intermittent main stea= safety valves lifting would step.

Redundanev To establish the degree of :edundancy previded by the various compenents discussed above, the staff and Licensee calculated the main coolant system cooldown times using varicus ecmbinatiens of the ce=penents. The staff's calculations are summari:ed below:

C:=cenent(s)

Results ADV 494*? in 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> 1-in vent 370*? in 50 hcurs A V + l-in vent 351*? in 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> (N 330*? in 95 hours0.0011 days <br />0.0264 hours <br />1.570767e-4 weeks <br />3.61475e-5 months <br />)

ACV + l-in vent

• I2FP 330*? in 48 hcurs 4

3~

.2 Franedin Researen Center a w.e % *m emeae

TER-C5257-310 Using these results to establish the :edundancy, it is apparent that,

even if all steam vent paths are censidered, the main coolant system cannot be cooled down within a reasonable period of time (defined as 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> in Standard Review plan 5.4.7). A single failure within the vent paths of the ACV cc 1-inch vent would extend the time :equired.

The staff also performed scoping calculatiens to determine the dependence of RCS cooldewn time on the initiatien time. It was found that, if the cooldown were delayed 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, the time to :each 330*F would be the same as if the cooldown began immed.ately (as socn as possible af ter the scram). Since

'the core decay heat is less at 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and the energy :emoval rate is the same, the cocidewn rate is higher initially, but then dec: eases as the energy remeval :ste (determined mainly by steam _ pressure) decreases.

Although the assumptions and calculating methods varied between the Nicensee and staff analysis, the Licensee's :esults support the staff

'ectclusien that the steam vent paths do not have sufficient capacity or redundancy to-satisfy the functional requi:ements of STP RSS 5-1.

In a March 26, 1981 letter [31, the Licensee prepcsed changes to provide, automatic quiet closure of the four main steam line non-return valves. This modificatien necess.itated ne installation of a new steam supply line to the steam-driven emergency feedwater pump and installatien of additional steam dump capacity.

During a Marca 27, 1991 discussion (4], the Licensee indicated that an additenal nanually operated du=p valve wculd be installed en each steam line upst:eam of the non-return valve. Eaca of these valves is to have the ability to :emcve appecximately 60,000 lbm/h. The Licensee stated tnat the new dump valves are intended to be the main method of decay heat removal following the loss of offsite ac pcwer.

The staff performed scoping calculations to assess the plant cooldown capability based on the proposed modification. A single failure was postulated to one manually operated dump valve and a decay time of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> prior to commencing cooldown was assumed. Based on these as-0 sumptions, a main coolant system temperature of 330 F. was attained in approximately 3.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. The results demonstrate that the proposed modifications as described would afford sufficient capacity and redun-dancy to satisfy the functional requirements of BTP RSB 5-1.

nadin Researen Cent 3-22

. :>.m. w er

TER-C5257-310 Based on the above discussion, the staff concluded that the steam reliev-ing paths did not conform to Criterion 4 and that the proposed modifica-tions (as described above) would provide sufficient capacity and redun-dancy to satisfy the functional requirements of BTP RSB 5-1.

These modifications were installed during the summer 1981 outage.

Iocatien and coeration The staff evaluated the equipment discussed above with respect to its location and cperability during a loss of offsite ac power.

able 3 2-1 shows the equipment's location, the points fecm which it =ay be operated, and its ipower supply. The design of the electrical inst:umentation and controls for this and other saf a shutdewn equipment will be evaluated in the electrical portion of the staff's review of Topic VII-3.

At:XILI ARY TEEDWATER SYSTIM Provide steam generatcr sakeup inventery whenever the main coolant Task:

system temperature is greater than 330*F and the feedwater system is inoperable.

Discussion

'cile the main ecolant system temperature is above 330*?, the ccre decay is removed by bleeding steam fecm the steam generaters using.he varicus heat f1'cwpaths discussed in previcus secticns. The cendensate and feed pumps are powered f:cm the 2400-V bus wnich is nor ally supplied frem offsite power.

Following a 1 css of ef fsite ac pcwer these pumps will not-be available.

4 4

3-23

-...a F anWin Res,eare.n Center aw.N a.

r v-e a

O

[a"j'If si Table 3.2-1 fu!

h EQUIPMENT 11X:AT10H CONTHOI POINTS EMXMH IC h

3 1.orge and manall Tu r t.i nie 1.uildlug,.adja-I4> cal manual operation only No electr ical gx)wer is nee. led.

k huggers cenit to condenser hotwell (Open/shtet steam inlet valves.

atout 50 f t f roin teed-water regulating valves, acid one fliglet of stairs below control roose.

Atmosphere duinp outside, in time vicinity Control rous operation and No electrical power is needed.

s, valve of the MSSVs, accessible Local operation using nitrogen by catwalk about 30 ft laottle pressure la the lower a

alove ground level.

level of the tutbine building.

1-in vent pipe Valves to !!sieup to cosi-te> cal operatiosi only using the No electrical power is needed.

1:o1 this patti are snainsal control valves.

located isi Llie lieatisig loller ruua; the 1-in vent pipe goes to ataio-sphere just outside the bolIder soosa.

HIFP See following section.

See following section.

See following sect {on.

'3 N

New atomospheric Manual No electrical power needed.

dump v_1ves 3

O e

TER-C5257-310 The auxiliary feedwater system is designed to supply water to the steam generaters for main coolant system decay heat removal when the normal feedwater system is not available. The auxiliary feedwater system is not normally used for other plant operations such as startup er shutdcwn. The auxiliary f eedwater system is initiated by starting the emergency boiler feed pump (:DBTP) locally and by cpening fcur normally closed manual valves in parallel discharge lines to each steam generater. The valve eparation is also accceplished locally.

The EBFP is a turbine-driven reciprocating pemp that provides a minimum of 80 gpm directly into the four feedsater lines immediately upstream of the l

air-operated feedwater regulating valves (FRVs).

Steam for the turbine is j

supplied from either main steam header via an automatic reducing valve or f

from auxiliary boilers.

Turbine exhaust is directed to atmosphere. The EBFP I

is lined up to receive water from the demineralized water storage tank and can '

also receive watee directly from the primary water stcrage tank. The IBTP discharges to the main feed system via a 2-inch (CD) teader. The header divides into fcur 1.5-inch (CO) lines, each of wnich pressurizes ene of the fcur normal f eed lines downstream cf the meter-cperated isolation valves (McVs). Each 1.5-inch (CD) line has a manual isolatien valve that is epened to pressurize the fcur feed lines. Steam generater level centrol is perferzed using the individual TKVs* frem the local station af ter the fcur MCVs are shut.

Reduniancy The auxiliary feedwater system consisting of a single EBFP and piping train is susceptible to single failures. A backup method of supplying feed-water to the steam generators in the event of failure in the auxiliary feedwater system is the charging pumps with a total capacity of approximately

• The TKVs are ncemally air cperated but can be anually cperated (during a icss of instrument air) using a handwheel.

4h

$h Franklin Researen Center 3-25 A On=en m *%e **w.an wumans

TER-C5 257-310 100 'gpm.

7.ro of these pumps have variable-speed motors. The charging and volume centrol system (CVCS) is connected permanently by a spool piece to the feedwater system. The operation of ten valves (two drains and eight isolation valves including manual valves C3-V-69 2, CH-V-751, CH-V-642, CH-V-641, ' and CH-V-689) is required to initiate fl,cw frem this source. The C7CS is also connected to the steam generator blowdown piping. Manual cperation to open valves C3-V-741, VD-V-1093, VD-V-1094, VD-V-1095, and VD-V-1096 is required to establish a feed path to the steam gnerators. Seth cf these paths use non-n'uclear system (NNS) piping. The water supply to the charging pump is the 135,000-gallon primary water storage tank ce the 30,000-gallen domineralized water stcrage tank.

The high pressure saf ety inj ection -(EPSI) and icw pressure safety injection (LPSI) pumps provide two additional methods of supplying feedwater to the steam generaters. The first path is from the safety injection discharge header through normally closed motor-cperated valves 3:-MCV-514 and

-515 and manus 1 throttle valve Si-V-445 to the charging header. Therefore, saf ety injecticn water can be directed to the charging header, and distributed to steam generators by the CVCS connections to the feedwater of blowdown p iping. Discharge fecm the EPCI and LPS: pumps can also be directed through manual valves SI-V-700, VD-V-1093, VD-V-1094, VD-V-1095, and VD-V-1096 to establish a feed path to the steam generators thecugh the blowdown system.

t 1

The flow available from the EPS: and LPSI sources is 200 gpm per train (three i

I trains available).

Pewer for the enarging pu=ps and meter-cperated valves is supplied fecm separate ncnsaf ety 480-V ac buses, wnich are capable of being fed by the emergency 480-V ac buses by remete manual cperation of circuit breaxers. The EPSI and LPS: pumps are connected to the 480-V emergency buses. ?clicwing a loss of ef fsite ac pcwer and a singis failure in the auxiliary fesdwater system, the charging pumps would not be availaole unless cperater action occurs to initiate manual operation of circuit breakers to supply emergency 1

i pcwer. In a :ecemcer 21, 1979 letter (51, the Licensee cencluded that there is not sufficient emergency diesel capacity to previde acesal pcwer to tne charging pumps and simultanecusly supply the existing emergency cere cooling i

O l

.' W Franicin Researen Center 3 -26 l

• w.a. wa -

l l

TER-C5257-310 requir ements.

S..tce the charging pumps are not supplied from emergency buses, the safety injection system may be required to fulfill functions normally assigned to the charging pumps (i.e., boration and primary plant makeup). In addition, the safety injection tank functions as a source of berated water similar to a refueling water storage tank in other Westinghouse' reactor f acilities. If the safety injection tank is used as an alternate scurce of water, the dissolved boren will be concentrated in the steam generators by the release of steam. The volume of water in the safety injection tank cannot be co'nsidered as an alternate source of water for the steam generators except under very extreme conditions. Consideratien of severe conditions warranting such use of the safety injection tank is outside the intent of the safe shutdown review.

Since the charging pumps cannot be censidered available as a backup method to feed the steam generators following a loss of effsite ac power and the saf ety injection system does not have a suitable source of water for steam generator feed, the auxiliary feedwater system as currently designed does not satisfy the functienal criteria of 3TP R53 5-1.

However, in Reference 5, the Licensee described proposed auxiliary feed-water system design changes to provide redundancy to the system. As proposed, the revised system consists of two 100-percent, safety-class electric pumps driven from redundant power sources.

The preferred flow path is to the exist-f ing auxiliary feedwater header. An alternate flow path is proposed utilizing the containment penetrations provided by the steam generator blowdown pipes.

[

Check valves in the blowdown lines direct auxiliary feed to the feed nozzle and prevent flow from entering the steam generator at the blowdown connection.

The motor-driven pumps can take a suction on either the DWST or the PWST.

The new pumps, located in the primary auxiliary building, are capable of being started either locally or from the control room.

The Licensee has indicated that the existing steam-operated EBFP will be restrained but its intended emergency function will be modified to mitigation of station blackout only.

In addition, the new auxiliary feedwater pumps are capable of being powered by the existing emergency diesel generators by remote manual operation of circuit breakers.

4 3 -27

..h F anidin Reseeren C. enter a wea w w r a

t

TER-CS257-310 Based on the above discussion, the staff concludes that the current

• auxiliary feedwater system does not meet the functional requirements of BTP RSB 5-1 but that the recently installed modifications satisfy the function-al requirements of BTP RSB S-1, except that the components are not connected to diesel-backed buses, although the capability exists for manual connection.

The reliability of the auxiliary feedwater system is being further evaluated by the staff under TMI Action Plan Item II.E.1.1.

i Location and Operation The staff evaluated the equipment discussed above with respect to its location and operability during a loss of offsite ac power. Table 3.2.2 shows the equipment location, the points from which it may be operated, and its power supply.

WATER SOURCES (DEMINERALIZED WATFR STORAGE TANK, PRIMARY MAKEUP TANK, AND SAFETY INJECTION TANK)

Task: Provide a source of auxiliary feedwater, primary makeup, and borated water.

Discussion The EBFP takes a suction from the demineralized water storage tank (DWST) via a 10-inch (OD) line which also serves as the hotwell makeup and rejection

(

l line.

This line leaves the bottom of the DWST and from there branches into the following:

1.

a 10-inch hotwell rejection line (i.e., flow from hotwell using condensate pumps and a level control valve) l 2.

a 10-inch hotwell makeup line 3.

a 3-inch EBFP suction line l

l l

4.

a 4-inch LPST makeup and charging pump suction line 5.

a 4-inch auxiliary boiler makeup line.

• Pre core-XV configuration O

• .15nkiin Resesren Center 3-28

• N r-

p.

>a Table 3.2-2 f

SE (L 3 CONTitOI. PolNTS EIJCTilIC 2

EO4II PHEt4T IdX! ATION 0

thergency boiler the corner of heating local operation only. Once at No electrical peeer is needed.

Q teed gnamp boiler tous floor, winich proper Epse, governor maintains

{

is a partitioned part of speed.

the turbine building.

Charging to feed Spool piecca and piping Incal mantJa! only.

No electrical power is needed.

systum upool flanges (and bolts) are piece in diargin9 Enamp cubicle.

Valves connecting to feed systua must be opened in j

si s',

lower level of turbine i

In:11 ding, in vicinity of BFPs (6 ft north of BFP motors).

Charging [nanpa ptsepaa are located in Ptsops operated frosa control CP81 - MCC 4. Dus 1 (400) aind Valves

'faepardIC ClihECles in rous or locally at. Liteir CPS 2 - MCC 2, Bus 1 (480)

Pall. Valves are under controllers (open door and use CP f3 - MCC 4, ilus 2 (480)

PAu floor, with reach jumpers). Valves are local

rods, ma,nstal only.

Control room or local.

2400 V Bus 2 Motor-driven PAB 2400 V Bus 3

([

Auxiliary Feed-g water pumps

.u U

EDG See emergency power See emergency power See emergency power system discussion system discussion system, discussion ho below.

below.

below.

_ _ _ _. ~ _ _ _

TER-C5257-310 condensate and domineralized water are stored in the CWST and the primary water storage tank (PWST). The DWST is an aluminum 30,000-gallon tank that is normally filled from the water treatment plant. The CWST is sized to handle all expected transients in the condensate /feedwater system. This is accomplished by providing makeup to and accepting rejected water from the

~

condenser hotwell.

The EBFP can also take a suction from the PWST via a 4-inch (CD) line i

which also serves as an alternate supply of water to the charging pumps. The

~ PWST provides domineralized water for the primary plant as well as for various

' demands in the primary auxiliary building, the radwaste building, and the spent fuel storage area. It is the supply for the low pressure surge tank makeup pumps and, as such, serves the above areas. The PWST is constructed of j

aluminum and has a capacity of 135,000 gallons. An inner floating roof prevents aeration of the tank contents. The tank receives makeup water directly from the water treatment plant.

Technical Specification 3.7.1.3 requires there to be a minimum combined volume of 85,000 gallons available frem the PWST and the CWS*.

The service j

water system (discussed later), which receives fresh water from Sherman Pond, supplies the water treating (WT) plant for PWS: and CWST makeup. The WT plant

• is sized to provide 40 gym of domineralized water on a continuous basis and 80 gym maximum, based en the average chemical analysis of Sherman Pend water obtained over a 1-year period.

The safety injection tank (SIT) is sized to provide a scurce of berated water to the safety injection pumps following a loss of coolant accident.

Another function of the SIT is to provide a source of water for flooding the shield tank cavity during refueling operations.

The SIT also prevides a source of borated water for the reactivity centrol system. Technical Specification 3.1.2.11 (Limiting condition for Cperation of Scrated Water Sources) requires that the S!T be operrole with:

4

'The WT plant is not includmi in the list of " minimum systems" but would pronably be availacle since it is essentially a passive system which is pressurized using the service water system.

du. ranklin Research Center 3-30 A h of*he F W denne

-~

rm._,...

--,e___-____wa_w.,e--,__x.,ame___

TER-C5257-310 a minimum contained borated water volume of 117,000 gallons of water, equivalent to a tank level of 2,25.5 feet a minimum boron cencontration of 2200 ppa e

e a minimum solution temperature of 40*y.

Redundancy The staff calculated the maximum length of time the plant can stay at het shutdown following the loss of offsite ac power, using the initial steam generator water inventory and a maximum DWST level of 30,000 gallons. The calculatiens show that approximately 20.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> water supply are available for main coolant system temperature control; af ter that, the nFP suction must be shif ted to the PWST. The staff also calculated that the total water inventcry required by Technical Specifications (85,000 gallons) is enough to keep the plant at het shutdown for about 73 hours8.449074e-4 days <br />0.0203 hours <br />1.207011e-4 weeks <br />2.77765e-5 months <br />. In Appendix B Part 2, Saf e Shutdown Water Pequirements, the staff determined the time required to complete a shutdown to the point of shutdown cooling system operation. Assuming (1) no credit for the initial steam generator inventory, (2) no condansate in the hotwell, (3) no single failure, and (4) use of the atmospherie dump valve, the 1-inch vent, the large and small hoggers, and the EBFP (all steam vent paths),

the staff determined that a water inventory of 72,000 gallons is sufficient to conduct the cooldown in 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. Further reiculations show that, if the l

plant stayed at het shutdown fer 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and then plant cooldown was l

initiated, the cooldown rates would be higher, but the ti:se to cool the main l

coolant system to 330*? would remain the same.

Since the cendensate pump motor is much smaller than the boiler feed pump meter (250 hp versus 700 hp), a single condensate pump dan be started to pump the centants of the condenser hotwell back to the CWST' for EFP usage. The DFP would not have to be stopped during this cperation since its suction e'

would just be augmented by the condensate pump (the cendensate pump rejection line would pressuri:e the DFP suction and fill the :WST). The hotwell has a capacity of 15,000 gallens and a normal cperating level of about 10,000 gallons. However, the betwell contents' following a loss of offsite ac power and subsequent feed and condensate' pump trips cannet be predetermined since l

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T23t-C5 257-310 event and component coast down times cannot be accurately predicted.

Therefore, no c: edit can be given for this inventory; however, it is likely that there would be a significant quantity of condensate available and usable.

The basis of the technical specifications for reactivity centrol systems states that the naximu:n boration capability requirement occurs at the end of core life f:om full power equilibrium xenon conditions and requires 9,192 gallons of 2200 ppm borated water from the saf ety injection tank. Since 11,7,000 gallons of 2200 ppm borated water is available in the SIT, the staff concludes that sufficient borated water capacity is provided to satisfy BRP RSB 5-1 functional : equi:ements.

The amount of main coolant system makeup during the cecidown (and filling of the pressurizer) from 539'F to 330*F'was calculated by the staff to be about 6,000 gallons. Since the cooldewn to shutdown cooling systs initiation used 72,000 gallons and since 85,000 gallens is available per technical spectiication, the staff concludes that sufficient primary makeup water is available to satisfy BTP RSB 5-1 functional :equirements.

I

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!.ocatien and Cteratien The staf f evaluated the equipment discussed acove wi h respect to its location and cperability during a loss of offsite ac power.

Tai.,le 3.2-3 shows the equipment's location, the points from which it may be cperated, and its power supply.

SHU"'DCWN C': CLING SYSTD4 Task: Remeval of core decay heat and main coolant system sensible heat l

l to cool the system f:cm 330*F to 140* F.'

Oiscussien The shutdcwn cooling system is placed in service af ter the main coolant i

temperature has been reduced to appecximately 330*F and.he pressure to less l

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TER-C5257-310 than 300 psig. The shutdown cooling system then reduces the main coolant temperature to 140*F or less and operates continuously to maintain this temperature as long as is required by maintenance or refueling operations.

The shutdown cooling system consists of a heat exchanger, circulating purp, piping, valves, and instruments arranged in a low pressure auxiliary loop parallel with the main coolant loops. The shutdewn cooling pump takes suction fecm the hot leg of the main coolant piping en the reactor side of the loop stop valves and recirculates main coolant water through the tube side of the shutdown cooler and back into the cold leg of the main coolant piping,

'which is also en the reactor side of the loop stop valves. The main coolant is contained in a closed system, and reactor decay heat load is transferred through the shutdown cooler to the ccmponent cooling system which in turn is cooled by river water. This arrangement of providing the intermediate cooling medium of the ccmponent cooling systent was selected in order to assure that any possible leakage of radioactive main coolant would not enter the river water.

The shutdewn cooling system is designed to remove the reacter decay heat about 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> af ter shutdown following 10,000 full pcwer hours of operation.

According to the licensee's estimates, about 16.2 x 10 Stu/h are generated by the reacter and transferred to the main coolant system.'

Redundanev Although the shutdown cooling ' system censists of a single cooler and cooling pump, a ecmplete backup of this system is provided by the icw pressure surge tank pump and cooler.

• he coolers and pumps are identical. The low pressure surge tank cooler and pump are connected in parallel with the r

shutdcwn cooler and pump. By employing double valving in the inlet and outlet lines of the main coolant piping, any ecmcination of pump or cooler can be used to maintain decay heat removal. Normally the shutdcwn cooler and

• Traf t ANS 5.1 decay heat curve predicts a p/?o 3 0.008 at t = 18.0 x 103 sec, or about 16.34 x 106 Stu/h.

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pump are aligned to the main coolant system and the low pressure surge tank cooler and pump are aligned to cool the low pressure surge tank.

By manual valve operation, a failed component in'the shutdown cooling system (SCS) can be replaced by a similar component in the low pressure surge tank cooling subsystem; therefore, the SCS has redundancy of components. Because of the sharing of common suction and discharge piping, the SCS is susceptible to passive piping failures, as well as failure of one of the motor-operated valves.

Failure to open of either a suction or discharge valve would result in loss of shutdown cooling system operation. As discussed in Section 5.1, alter-native methods of cooling exist, therefore, this deviation from the review criteria is considered acceptable.

Based on the above discussion, the staff concludes that the SCS satisfies the functional requirements of BIP RSB 5-1 except that the SCS and LPST cooling pumps are not normally powered from diesel-supplied electrical buses.

The staff will evaluate the significance of this in the SEP integrated assessment of Yankee Rowe.

focation and Operation The staff evaluated the equipment discussed above with respect to its location and operability during a loss of offsite ac power. Table 3.2.4 shows the equipment's location, the points from which it may be operated, and its power supply.

COMPONENT COOLING WATER SYSTEM Task: Provide cooling water to the SCS and/or LPST coolers and to other essential equipment.

Discussion The component cooling system is necessary to remove reactor decay heat from the shutdown cooling system heat exchanger (or the. low pressure surge tank cooler) and to provide cooling to equipment necessary for plant cooldown.

The component cooling system consists of two coolers, two circulating pumps, a surge tank, a chemical addition tank and associated piping, system and instrumentation piping, valves, fittings, and instruments. This equipment is connected to two main piping headers. One supplies vapor container 4

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[ua ip gy81PMEttr iiC ATI(44 CottritCI. POINTS EI.tC1H IC a

4 SCS and 1.PST Cubicles in tiio Pall, The SCS and LPST cooling pianpa SCS pimaps lius 5-2 (480 V) cooling lausps lower level.

are operated true the control LPST cooling pumps lius 6-3 acid coolers roun and can be operated (400 V) locally during asi esmergency by jumping the cell switch and us.ing the test control switch at the switchgear w

,e, cubicle. The coolers re-quire local, smanisal valve oper ation sancia that operation true the cositrol rous la not Ex)s si b le.

Sc3 valves See Sections 4.1 asid See Sections 4.1 and 4.2.

See Sections 4.1 and 4.2.

4 ' 2.

6 DJ 5

l

r TER-CS257-310 components, the other supplies equipment outside the containment. Independent lines, provided with isolation valves located outside the vaper centainer, are connected frcm the vapor container supply header to the various ecmponents inside the vapor container.

A surge tank (4,000 gallons) is used in the compcnent cooling system to provide =akeup water for the system, to acecmmodate the expansien and centraction of the water in the system as temperature changes, and to act as a receivar for the saf ety valves in the ecmponent cooling lines. The water level in the tank is maintained at approximately 2,500 gallons. The surge tank is equipped with a vent to the primary vent stack and a safety valve which discharges into the vapor centainer drain tank.

Level controls and alarms are provided on the surge tank. A low pressure alarm and control switch is located on the common pump discharge header and l

pressure indicators are provided in the outlet of the component cooling pumps.

A pressure switch starts the standby pump on low pressure.

The common cooler inlet and outlet pipes are provided with local and remote temperature indicators. The inlet pipe has a high temperature alarm, and the outlet has a flow meter, and a low flow alarm.

Controls for the component cool-l ing pumps are located on the nuclear auxiliary panel in the main control room.

Two motor-driven centrifugal circulating pumps are provided. The capacity of each pump is approximately 2,000 gpm, with a total dynamic head of 190 feet i

of water and a design discharge shutoff pressure of 110 psig. The switches may i

be set in "Close", " Auto", or " Trip" position with provision for " Pull-out" in the trip position.

t The two component coolers are of the shell and, tube design and are provided to transfer heat from the component cooling water (CCW) to the service cooling l

water.

The tubes are made of admiralty metal.

s During a cooldown of the main coolant system following a loss of offsite ac power, the SCS is used to circulate the hot main coolant through the SCS cooler (tube side).

The shell side of the cooler is furnished with CCW, and D

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the cooldown is controlled by an air-cpe:ated temperature control valve *

(T/-20 0 ) en de cod discharge of the I2SC and SC:: coolers (cc= men line).

TI-200 controls either the :.PSC or SCS return (to the RCS) te=perature at-

.t',

x 140*F by throttling the cceponent. cooling flew fecm tse coolers. 'ahen the SCS

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cooler 'is first placed on line, the heat Icad is greatest and the SCS :eturn temperature i~s highest', so the maximu:a cod flow to the SCS cooler is s'.lc\\hed.

• dhen the SCS to RCS temperatu:e.d: cps, then de C04 ficw 'is reduced to decrease the he'at remcval.

-s s

Redundanev i

i Zach cooler is designed for the full cooling capacity reachec duric.g 6

normal plant operation (8.5 x 10 Stu/h) and either cooler serves as' a spare fer the other; they can be operated in parallel, if required. Also, each cooler can remove ce maximum decay heat removed by the SCS cooler (16.0 x

'6 10 Stu/h) with the same amount of C04 flow.

Norma 1 Icad Fu1;i :nad Eeat removal (x 10 Stu/h) 3.5

,16 JC COA inlet temperature 100.5'F 36.0*?

C04 outlet temperature 92.'0*F S0.0*F Service water inlet temperature 91.0*F 60.0*F Service water cutlet tempe:ature 87.S*F 72.3'?

cod flew 2000 gym 2000 gym S*d ficw 2500 gym 2500 gym Iach pu p can be cperated singly er in parallel and is provided with a

edundant independent pcwer supply.

In addition, there a:e inscalled hose cennecticns at the COA pu=p discharge and suction to allow service water c: fire water to provide

'CCI-200 is normally air Operated but f ails epen (during a icss of inst:ument air ). Cent:ol of the cod flew can thereaf ter be acecmplished using the manual isolation valve.

3 1O

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i 1

1 TER-C5257-310 corrponent cooling should both CCd pumps be incperable or if a rupture in the system has occurred.

"he precedure (CP3115 - Loss of Component Cooling) directs the operator to attempt first to hook up to the portable fire hose from the fire system to the CCA system, then, if unable to use the fire system, to use tne ser0 ice water system. Thus, there are ;edundant and diverse means to provide component cooling.

Based on the above discussion, the staff concludes that the cod system satisfies the functional requirements of BTP RSB 5-1, except that the electrical components are not powered f cm diesel supplied electrical buses.

The staff will evaluate the significance of this in the SEP integrated assessment of Yankee acwe.

L:catien and 0:erstien a'

The staf f evaluated the equipment discussed above with respect to its locatien and operacility during a loss of offsite ac power. Table 3.2-5 shows the equipment's location, 'the points f cm which it may be-cperated, and its power supply.

SIRVICE NATER SYSLM Task: Previde coling water to the ecmponent cooling water coclers and the SCS pu=p and/or iPST' cooling purry coolers.

Discussion The service water system censists of ?!.ree 2,300 gym vertical deep well type pumps which cetain their suctica f cm a ecmmon intake well in the circulating water pump house. O e pumps discharge to.a ecemen 12-inch header which branches into two 12-inch supply headers. The supply headers run parallel to the southern wall of the turbine recm basement.

"he two 12-inch supply headers furnish the varicus components with service water via separate taps frem ene er both of these two main supply headers. Se headers can be (manually) cross-connected so that any ecmbination of pumps supplies the necessary leads.

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ik t:Otll PHt:H'r I A x?ATIOta CONTitOI. ICIllTS EI.LI!'IN IC 1,9 lO CCW gamups (2)

Bottom floor level of

. operable frcan the control CCW ptmp 01 - bus 13 (2400 v) the PAB, NW end of r o(sa. Can be operated locally CCW taune 12 - 1 sus 8 2 (2400 v) building, under CCW in an emergency by jamaping coolers.

the cell switcle and using the test control switcle at the 2400 V breaker.

CCW coolens (2)

Side-Isy-side, ut.pe r level Incal-1aanual operation of No electr ical gewer is needed.

o f P Ali, SW end of tailld-valves.

1 ing, adjacent to CCW surge tank.

CCW twise tittings Incat ed 4L varions places Incal-imanual operation only.

No electr ical gewer is needed.

and gottable hoses in the SW end ut the Pall, all within atx)ut 50 ft.

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4 E

TER-C5257-310 The greatest heat had on the system occurs when the SCS is first placed in cperation. A total of 2500 gpm of 60*F cccling water is required at that ti:n e.

This sane flew is :equired at any time when the main ecciant systen water chemistry requires operating the purificatien systen at its maximum capacity of 100 gpts. There is adequate capacity in the service water pumps to meet these special operating ccnditions.

Redundancy Normally, two ptrips will be in operation, with one pump en standby. If

' he pressure in the discharge header falls below a preset value, the standby t

pump will start and simultaneously an alarm will be given at the main control teard. The pressure switch for initiating this standby cperation is located in the turbine reem and is set at appecximately 50 psig.

1 The 2400-V power supplies to service water pumps #1, 2, and 3 are Bus 63, 3us 91, and Bus 6 2, respectively. These buses can be separated so a fault in one would not disable any'more than one service water pump.

Should all peps fail due to electrical problems, localized da:nage in the sc:een hcuse, or less of sucticn f:cm She: man Pond er if a break aff ecting certain portiens cf the service water header should cecur, selected service water leads can be provided with eccling water f:cm the fire system. The fire systen could be supplied by either the installed fire ptups ce f:cm portable fire pumps connected in series taking a suction fran the :iver c f:ca She= nan Pend. Also, the petable water systen can supply selected service water leads with eccling water. The plant peccedure (CP-3009, T. css of Service " dater) descrites which conpenents may receive fire water er petable water and the

• ccations of the necessary connecticas.

Based en the aceve discussien, the staf f concludes that.he service water systen satisfiee the functional requi:enents of BT? RSB 5-1, except that the electrical ecmponents are net pcwered f:cm diese:-sup;1ied electrical buses.

The at ff will evaluate :he significance of his in the SIP integrated assessnent of Yankee Rowe.

A JMeanidn Research C. enter F

3-4 *.

4 w e w r-u.

TER-C5257-310 Location and Oceration The staf f evaluated the equipment discussed above with respect to its locatien and eperability during a loss of of fsite power. Table 3.2-6 shows the equipment's iccatien, the points f:cm which it may be cperated, and its power supply.

PRESSURE CONTRCL AND RELIIF SYSTDi Task: To maintain a system overpressure during het standby and/or natural circulatien cooling and to depressurize the main coolant system :o

' permit the initiation of the shutdewn ecoling system and to cool dcwn the pressurizer.

Discussion I

t The pressure centrol and relief system primarily functiens to maintain the :equired ' main coolant pressure at the reactor outlet during steady-state eperatien, to Ibnit to an allowable range the pressure changes caused by main coolant the: mal expansien and contracticn during no=st :. icad t:ansients, and to prevent the pressure in the main coolant system f:cm exceeding the design pressure. The pressure control and :elief system censists cf a ;:essurize:

vessel centaining a two-phase mixture of steam and water, i=mersion heaters,

saf ety and :elief valves, spray system.ntercennection piping, valves, and inst:=m entatien.

Depressuri:stien cf the main coolant system in pressuri:ed water reacters is generally achieved by the pressu:i:er in conjuncticn with one er more of the ic11cwing:

(1) the main pre ssu:i:er sp:ay, (2) he auxiliary pressu:i:e:

spray, er ::) the pressuri:e: :elief valve. The p:essuri:e: spray nc::le is located in :ne manway at the tcp cf the pressuri:er. The spray pipe is connected to the main :colan system inle: pipe en the :eac:ce side cf ice:

number 2 isclatien valve. This connection is in the feca of a scocp inside the coclant piping, so that the velocity head plus the static pressure dif fe:ence between this connecticn and the surge pipe connecticn ;;cvide the maximum pcssible driving force for spray flew. A meter-cperated valve en the spray can :e cpe:ated :y a swi:ch en the main cent:01 board.

4 34 I

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/,2" TADI.E 1.2-6 lh ct EOtflPHEt4T IiX?ATION OPEHATION POWER SUPPI.Y SWPs (3)

Circulating water pump Operable from the control SWP 81 - Bus 83 (2400v) lu>use ro(aug can be operated SWP 82 - Dus II (2400v) locally in an emergency by SWP 83 - Bus 82 (2400v) jumping the cell switch and using the test control 1

switch at the 2400v breaker w

Hose connections

. Inlet and outlet to the Local-manual No electrical power is needed to SW system CCW coolers A

0 G

Q O

TER-C5257-310 Policwing a less of offsite ac pcwer, the main ecolant pumps are not available to sustain prima:y coolant flow; therefore, nc= mal pressuri:er spray flow is not available fer main coolant system depressurization. As a consequence, depressuri:atien of the main coolant system must be achieved with either the auxiliary pressuri:er spray or the pressuri:er solenoid-cperated relief valve, PR-SCV-90.

The solenoid-operated relief valve can be operated manually by a switch in the control rocm. A motor-cperaked valve placed on the solenoid valve inlet piping is provided for isolation of the solenoid valve.

The steam and/cr water discharged from the solenoid-operated relief valve will discharge directly to the containment atmosphere via a rupture disc in the line.

For this reason, this method would be used as a last re8 ort.

The auxiliary spray line is located in the chemical and vol=me centrol system.

It.s connected to the feed line downstream cf the feed and bleed i,

heat exchang ers. This, arrangement pec its cha:ging of water by the high pressure charging pumps i.7to the top of the pressurizer.

Following a loss of offsite ac power, main coolant rystem pressure cont:cl is necessary to maintain an adequate subcooling margin and assure no disruptica of the natural circulation flow. Once natural circulation is achieved, system pressure conteel wculd be accomplished by maintaining a systcm eve: pressure with the pressurizer threugh use of the chemical and volume cont:cl system or pressuri:e: he at e rs.

There are 48 pressuri:e:

heaters combined into 24 groups. The 24 g: cups are ecmbined into eight 3-phase groups of 37.5 kW capacity.

Redundanev In an April 9,1980 letter (6), the Licensee indicated that cperating experience at Yankee 3cwe has demonst:ated that the operation of one group ':f pressuri:e: heaters (37.5 kW) is required to meet the heat 1 css f:cm the pressu:i:er with normal spray flew th:cugh the pressuri:er at het standby conditiens. The ability to maintain natural circulatien under emergency conditions would require less capacity than for no=nal cperations. The Licensee also indicated that Westinghcuse had perfc=ned a study to dete=mine O-dJ F anidin Research C. enter 3-44 4 w w N r-u.

TER-C5257-310 minimun heater requirements without offsite power and that extrapolation of the results of this study to the Yankee Rowe pressuri:e: confirmed the

equired heater capacity.

The Westinghouse study also detecnined that the capability to supply emergency power to the heaters within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> would prevent loss of subcooling in the primary rysten following a less of effsite power. The Yankee Rowe f acility has four groups of pressuri:er heate:4 connected to 480-7 Bus 6-3 and four groups connected to 480-V Sus 5-2.

Each of these buses is connected to an emergency bus via two circuit breakers in series, and these tie breakers are operated frem the main centrol room. To supply the required heater capacity f:om the energency bus, Bus 6-3 and Bus 5-2 are cleared and the buses are re-energi:ed by closing the tie breakers to the emergency buses. The Licensee indicates that the time :equired to accomplish this, giving due censideratien to all requirements of plant cperating p:ccedures, is 15 minutes from the occurrence of the loss of effsite power.

In a Maren 19, 1981 ietter (7), the Licensee desci 3 ed design features of L

a pecposed alternative saf ety shutdown system ( ASSS). "' e Licensee indicated that the ASSS is designed in ecccrdance with requirements of Appendix A to 10CTR50 as further clarified in the NRC Generic Letter 81-12, dated February 20, 1981. The preposed design has ene g: cup cf pressuri:er heaters being powered by #3 diesel generator through a new 480-V ASSS motor control center such that main coolant system pressure can be maintained. One group of heaters is capable of maintaining a hot shutdown condition.

As described, the pressure centrol and :elief rystem has two methods of I

depressuut:stien. A single failu:e of the solenoid-cperated relief valve or its biceking valve would not preclude the capability to depressuri:e, provided auxiliary p:essurizer spray flew is available from the chemical and volume l

centrol system.

The availabi'ity of this flew path is assessed in the discussien cf the chemical and volume cont:o1 system.

Based en the above discussien, the staf f def ers evaluation of the adequacy of the pressure cent:ci and relief system to satisfy STP RSS 5-1 pending resolutien of current staff reviews of applicable TMI-2 action itens 1

l d'bnk!in Researen Center 3-45 a w.# w ma sma.

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l TER-C5257-310 and fire protection requirenents. The staff will determine the effect that l

the completion of these reviews will have on the safe shutdown topic during l

the integrated assessnent.

i l

Iocation and Oceration The staff evaluated the equipment discussed above with respect to its location and cperability during a loss of effsite ac power. Table 3.2-7 shows l

the equipment's location, the points from which it may be operated, and its power supply.

CHMICAL AND VOLCME CCNTRCL SYSTM Task: Provide main coolant systen makeup (due to the contraction of the coolant during the cooldown), to provide a flow path for borating the main l

coolant systen to the necessary shutdown margin, and to provide a means for f

depressuriration of the main coolant systen.

Discussien The chemical and volume control systen censists of three positive

[

displacement charging pumps, f eed and bleed heat exchangers, pressure reducing orifices, LPST, LPST cooling pump, LPST cooler, LPST makeup pumps, and associ-ated piping, valves, fittings and instruments.

During normal cperation, bleed flow passes frem No.1 loop T line, through the tube side of the feed and bleed heat exchangers, through the vari-orifice, and finally into the LPST through an eductor. Charging flow passes frem the purification pump discharge through the charging pumps, through the shell side of the feed and bleed heat exchangers, and into No. 4 locp T line. In addition, charging flew can be lined up to the individual h

loeps via the saf ety injection systen.

Each charging punp is a positive displacanent reciprocating pump rated at 33 gym, 2500 psig and driven by a 5.0-hp =ctor.

No. 1 and 3 pumps have variable speed drives.

No. 2 pump is directly ecupied to its actor and its A

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g3:s EOUIPMENT IIX?ATION OPERATIOtt POWER SUPPI.Y G

Pit-SOV-90 Va[or Cositainer Cositrol ik>un Battery 11 Salesiold Operated P ess,urizer itellet valve PR-HOV-512 Valor Container control lioon 480V thergency Y

Pressurizer Relief MCC 1 Is ulock inaj Valve Pressurizer Vapor Container Control N oa Eksu 5-2 (4 groups) lleaters bus 6-3 (4 grougs)

Pit-MOV-191 Vagor Cositaisier Control M ua MOCl Bus 2 Main Pressurizer s

Spray Flow Iso-latioin Valve G

'e N

A.

u N

O e

~._ _ _. _ _ _.

TER-C5257-110 constant speed.

No. 2 pump could put out a variable flow by throttling CH-V-690 between the discharge and suction of the pump.

i Charging pump suction can be from the following sources:

1.

LPST (gravity flow) 2.

Purification system (IX-gravity) 3.

Purification systen (pumps )

4.

Boric acid mix tank (gravity) 5.

Saf ety injection tank (gravity) 6.

WT systen (via LPST makeup pumps) 7.

PWST (gravity or LPST makeup pump) 8.

DWST (gravity).

Beration of the RCS is acconplished by injecting torated water frer, either the boric acid mix tank (1500 gal at 12.0 to 12.54 by weight-min) or the saf ety injection tank (117,000 gal at 2200 ppm-min). The SI tank is c

nor:nally used sir *ce it provides finer reactivity cont:o1 because of its lower

$c'ron concentrations however, the boric acid mix tank is also available.

A means for depressurization of the main coolant system is provided by the auxiliary spray line.- It is connected to the feed line downstream of the j

feed and bleed heat exchangers. To initiate auxiliary spray ficw, j

meter-cperated valves CH-MOV-524 and PR-Mov-191 are closed and manual valve CH-V-6'13 is cpened and throttled. CH-MCV-524 and PR-MCV-191 are operated remote manually f:cm the centrol room: however, access to tne vapor container is required to locally operate CH-V-613.

I,

(

Redundancv To ensure that the pressuri:er level can be centrolled during the most i

rapid cooldewn (i.e., ensure sufficient charging pump discharge) the staff used the calculations of the main coolant system cooldewn with the 1-inch vent af ter a wait time of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. This cooldewn : ate was initially (i.e., at,-

T

= 540*F) slightly greater than 50*F/h. The staf f calculated that the liquid centracticn rate due to the cooldewn at about 50*F/h is less than the input rate available fran each charging pump. Therefore, he pressurizer level can be raised by caly ene charging pump during this cooldewn, and the renaining pumps provide further redundancy.

O I.%5nidin Research Center A Cheer 1 et The Fw swanas

I

.ER-C5257-310 Borttien cf the main coolant system cannot be accomplished at Yankee Howe without the charging pumps unless primary system pressure is reduced to allow use of the low pressure and high pressure safety injection pumps. The shutoff head of the high pressure safety injecticn pumps is 1850 feet, while that of the low pressure pumps is 1530 feet. Assuming that the low pressure safety injection pump is used as a booster pump for the high pressure saf ety injection pump, the shutoff head of the safety injection system corresponds to approximately 1470 psi.

In order for the safety injection system to be a viable path for borated water addition, depressuri:ation of the main coolant systen would be required. As discussed in the previous section, two means are available to depressurize.

If a single failure is postulated in the pressure control and relief systen (i.e., solenoid-cperated relief valve does not open on desand), the auxiliary spray flow from the chemical and volume control rystem is required. In order to ensure the availability of this depressuri-zation method, the charging pumps must be available.

A backup path for charging flow is from the charging pump discharge via CTT-MOV-522 to the loop fill headers. Motor-operated valves in one of the safety injection lines would be opened to direct the charging

~

flow into a cold leg. These valves are remote-manually operated from the control room.

Primary coolant can be letdown via sample and drain lines. All valves are operable from the control room or at the sample sink.

The charging, pumps are not powered f rom the 480-V emergency buses.

The Yankee Rowe facility has three charging pumps powered from three different 480-V buses. Each of these buses is connected to an emergency bus via two circuit breakers in series, and these tie breakers are oper-ated from the main control room. To supply the charging pumps from an emergency bus, the non-emergency buses are cleared and then re-energized byclosing the tie breakers to the emergency buses.

In Reference.7, the Licensee proposed that a charging pump and associated motor-operated valves be powered by #3 diesel generator through a new 480-V ASSS motor control.

center.

Based on the above discussion, the staff concludes,that the chemical volume and control system does not meet the functional requirements of BTP RSB 5-1 in that the charging pumps and other electrical components are not powered from diesel-supplied electrical buses. The staff will evaluate the significance of these deviations during the SEP integrated assessment of Yankee Rowe.

l l

B-49

N Location and Operation The staff evaluated the equipment discussed above with respect to its location and operability during a loss of offsite power. Table 3.2-8 shows the equipment's location, the points from which it may be operated, and its power supply.

I CONTROL AIR SYSTEM Tank: Provide compressed air for instrumentation and the control of air-operated valves in other safe shutdown systems.

Discussion The No. 3 control air compressor is a two stage rotary screw comprescor rated at 435 scfm. at 100 psig. This compressor is directly driven by a 1800 rpm,100 hp, 480-V motor. This compressor normally supplies both instru-ment air and service air requirements.

Two 125 scfm, 600 rpm control air compressors with V-belt drive and 25 hp motors provide backup air at 100 psig. to the instrument and control air system.

Each compressor can operate in one of two modes. A local control switch with "Off-Hand-Auto" positions actuates the starter for each compressor. In " Hand" position, the compressor runs continuously with the compressor loading and unloading automatically to maintain receiver pressure.

In " Auto" position, the compressor motor is started and stopped automatically to maintain receiver Each compressor is sized to provide 100% of the station's compres-pressure.

sed alt requirements.

The vertical, single stage, double acting, reciprocating, water-cooled compressors are of the non-lubricated carbon or teflon ring type and are installed with aftercoolers, air receivers, and intake filters.

The discharge from each control air receiver supplies one header of a double header piping system that runs throughout the station. The two control air. headers are cross-connected at the receivers in the turbine area and in the primary auxiliary building. Air from each header is supplied through reducing valves, as required, to each instrument or control air supply manifold in the turbine area and primary auxiliary building. The reduced air station i -

l within the main control board has a low pressure alarm at 25 psig. The control I

l air header low pressure alarm is set at 75 psig. A solenoid-operated bypass valve that opens at 65 psig connects receiver and header directly.

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1(5 Changing Puste (See t31FP discussion)

(See HIFP discussion)

(See HtFP discussion) 13) poric A:!d Mix tgiper level of PAD in local manual operation only Mechanical agitator is powered Tank general vicinity of the (tilling, etc.)

from MCC4 Bus 1, trace contunent cooling water heaters from HCC4 Bus.2, and surge tank redundant trace' heaters fron-e=ergency Ekas 1.

in L

Sa f e ty Injection Outside of the safety Tank la filled by. lining

,1here is a small heat,, exchanger Tank injection l>ullding, up various valves in the and circulating pump which keeps west of the waste pan. Suction path to SIS the water between, 120-130*F, but I disgesal building is automatically aligned these not necessary following the loss of AC.

Therefore,'no elec-trical power is needed.

C81-MIN-52 4 Inside valor containment Control room 400V Emergency MCC1

~

Cil-M(N-5 2 3 In PAH next to charging Control rooss 480V Emergency MCCI

[xangas A

N Cil-MOV-525 Inside vagor containment Control room 400V McC1 Dus 1 A

sa ICV-222 I n P All Control room M

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e

TER-C5257-310 Redundancy Following a loss of offsite ac power, the control air compressors would not be available, since they are powered from non-emergency 480-V buses.

Loss of the air compressors event 6 ally results in a complete loss of control air to safe shutdown equipment. Operating Procedure 3002, " Loss of Control Air Supply", defines the immediate operator actions required to place the plant in a hot shutdown condition.

Upon loss of offsite ac power and control air supply, safe shutdown components are affected as follows:

PCV-451 (steam supply to emergency boiler feed pump) will close if o

open. This valve supplies steam to the turbine driven emergency feed pump.

o TV-405 (auxiliary steam trip valve) will close.

This valve supplies steam to the large and small hoggers.

TCV-200 (cooling water return CCW system) will open. This valve o

controls component cooling water flow through the LPST cooler and the SDC cooler.

TCV-205 (cooling water return CCW system) will close. (VC) o o LCV-222 (letdown line level control valve to LPST) will close. This valve controls letdown flow rate to LPST.

o TV-411 (atmospheric dump valve) will close. This valve provides a path for sensible and decay heat removal.

CV-1100A, B, C, D (bypass valves around feedwater blocking valves) o will lock in position.

These valves provide a bypass path around motor-operated feedwater blocking valves.

o CV-1100, CV-1200, CV-1300, and CV-1400 (feedwater regulating valves) will lock in position. These valves control feedwater to the steam generators.

Wide and narrow range steam generator water level transmitters will o

I indicate low steam generator level.

I Variable speed charging pumps will not control from the main control o

board.

(One charging pump controller is locked in the full speed position.)

o Indications from pneumatic level instruments will be erratic, including pressurizer pressure.

Following a loss of control air, the operator can valve in emergency nitrogen supply to the atmospheric dump valve and the auxiliary steam trip

'I2

.... Franklin Researen C. enter 4 wea w N r,.,

TER-C5257-310 valve. In additien, the operator would control steam generator levels by using manual bypass valves. With erratic pnetznatic steam generator levels, the operater must rely on the electrically transnitted steam generator level signals in the switchgear rocm, or the electric level indication on or-inside the main control board can be used.

The service air systan is ancther source of pressuri ed air. Service air is provided by one 514 scf:n service air compressor with V-belt drive and 10,0-hp motor. The vertical, single-stage, double-acting, reciprocating, water-cooled ccupressor is of the lubricated type and is installed with intake filter and air receiver. The 100-hp, 440-V motor is powered from non-energency bus 4-1 and controlled by an air circuit breaker with ll3-V de control in the 440-V switchgear. Operation of the circuit breaker is controlled fecm a locally mounted 3-position switch. The type of autanatic centrol for this ecmpressor duplicated that provided for the centrol air ccupressors.

The discharge frem the service air receivers supplies a single hee. der piping system which runs throughout the station. This system is intercennected with the control air system. The service air systen can function as a backup to the control air systen during no: mal cperation.

Fo11cwing a loss of of fsite power and/cr a single f ailure, the system cannot be relied upcn to function and therefore is not censidered to be a safe shutdewn systen.

The control air system provides pressuri:ed at: for necessary valve control functions within safe shutdown systems and pneumatic signals in essential instrumentatien. Icss of the c:mpressed air system will not prevent reaching a safe shutdewn conditien, but it is detri= ental frem the standpoint of causing numercus manual valve Operations and er:enecus indication to the operators. These additional actions are beycnd the limited Operator actioris that may result :cm a single failure.

Based en the abeve discussi :n, the staf f concludes that the centrol air systen dees not satisfy the fune._ional requirements of 3TP RS3 5-1 in that a A

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~. _ _ _ _, _ _ _ _

TER <5257-310 reliable source of control air is not available and significant operator action outside the centrol roca is required to ef fect a safe shutdown. The staff will evaluate the signifiusnce of this in the SIP integrated assessment of Yankee Powe.

• ocation and Coeration The staf f evaluated the equipment discussed above with respect to its location and operability during a loss of offsite ac power. Table 3.2-9 shows the equipment's location, the points frem which it may be cperated, and its power supply.

DiERGI CY PCWER SYSTIM Task: Supply a reliable source of'ac power to run the necessary equipnent.

f Discussion

• he three energency diesel generaters (EDGs) are each rated for continuous operation at 500KVA, 480v, 0.8 pf, and 1800 rpm. "The engines are fast-starting, V-16 (cylinders ), two-cycle, water-cooled engines dat are direc:1y coupled to an air-cooled synchronous generator.

• ach engine has a closed, self-contained water cooling cycle and is started with a 125-V de cranking motor that is supplied with power fran an independent battery.

Air for operation of the engine and for cooling the generater and engine radiator is obtained fran roof intake vents. The cooling air exhausts to the outside atmosphere, and the engine exhaust is via a muffler.

Each EDG has a 275-gallen fuel oil supply tank w'hich centains enough fuel for 11.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> at full load. A 30,000-gallen fuel oil storage tank can supply' any supply tank via gravity flow. The storage tank Technical Specification minimum (8,000 gallons) can supply enough fuel for all EDGs at required load for more than 7 days. !C-Icw level in the.hree supply tanks is annu.x::iated in the centrol rocs.

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h s control air First floor of 1.acal control (1) 480V HCC 2 Dus 1 cosapressor s turbine building switch (2) 480V MCC 1 Dus 1 I

• ~ One service air First floor of incally mounted 480V station service

'l u,

ctmpressor turbine building switch switchge.ar bus Sect. 4-1

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Tne rotary non-First floor TB Locally mounted 480-V station service

• • - lube air switch switchgear Bus Sect. 4-1 compressor

• Standby equipment l

Normally supplies both service and instrument control air h

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TER-C5257-310 Redundancy Each of the th~ree EDG's are rated at about 536 hp (400 kw), which is sufficient to supply the necessary electrical loads during shutdown and cool-down of the plant. However, since the emergency buses, powered by the EDG's, are normally connected to safety injection loads, manual operator action is required to disconnect these loads and feed the shutdown loads.

The EDG's are further evaluated in the resolution of SEP Topics VII-3 (electrical portion) and VIII-2.

Location and Operation The staff evaluated thesequipment discussed above with respect to its location and operability during a loss of offsite ac power. Table 3.2-10 shows the equipment's location, the points from which it may be operated, and its power supply.

3.3 Safe Shutdown Instrumentation Tablea3.3-1 lists the instruments required to conduct a safe shutdown.

The list includes those instruments which provide information to the control room operator from which the proper operation of all safe shutdown systems can be inferred. These instruments are the RCS pressure and temperatures, pressurizer level, and steam generator level. Improper trending of these parameters would leed the operator to investigate the potentfal causes. Other instruments listed in the table provide the operator with (1) a direct check on safe shutdown system performance and (2) an indication of actual or impending degradation of system performance. The list of instruments satis-fies the requirementaof BTP RSB 5-1 for safe shutdown. The DBE evaluations, which in many cases are not based on the same assumptions as this review, may determine that additional instrumentation is required to achieve and maintain a safe shutdown following a DBE.

The design of the instramentation and controls used for safe shutdown will be evaluated later in the electrical portion of the resolution of SEP Topic VII-3.

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E@IPMENT IDCATION OPERATION POWER SUPPI.Y i

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usergency diesel Diesel generator Control roose Start il 125V DC Bus 1 generators building Start 82 125V DC Dua 2 Star t 93 Battery Dist.

Switchboard 3 I

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TABLE 3.3-1 SAFE Sil0TDOWN INST 130MENTS Cutronettrl

• b.

SYSTtM ItaSTutiMLtrF INSTHUMENT IDCATION n

[)d Steam cenerator Steam Generator I.evel Control noom (Indication and alarm) t (LT6L1 tw-1001, 1101, f

pg.

1201, 1301 (WH)I m-100 3,

==

1103, 1203, 1303 (NR) )

15 g

Steam Generator Pressure Control Room (Indication) l

[g (PIT-MS-403, 4, 5, 6) i Anal 11ary Feed System Demineralized Water Storage Control Room (Indication and alarm)

Tank I.evel (LIT-405) j i

Auxiliary Feedwater Flow Control 14oom (Indication)

Chemical and Volume Charging Flow (FI&FT-2)

Control Room (Indication and alarm) as

.j 1

Control System I.eldown Flow - (FI6 tT-1)

Control Room (Indication)

~

I

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Shutdown Cooling SCS Flow (FI-204)

Local (Indication)

System Component Cooling CCW Flow (FI 6 ET-201)

Control Hoom (Indicatiosi and alarm)

Cooling water Supply Control Room (Indication)

Temperature (TI-222)

Control Room (Indication and Alarm)

Service Water System SWS Flow local (Indication)

Main Coolant System Pressurizer Level (WR)

Control Roosa (In<t icatioen and alarm)

(PH-LD-8) g Pressurizer Pressure Control 140oen (Indication and alarm) u (PH-PD-6, PR-PT-700) u Main Coolant System Control Hoom (Indication and alarm) 4 (MC-PD-9) g Safety Injection SIT !.evel Control Room (Indication and alarm)

Tank (SI-I.T-1 )

E naN h

TABLE 3.3-1 (Continued) in U

ft COMPONEffr/

SYSTEM INSTHUMIWF INSTRUMENT IDCATION Primary Water PWST I.evel Control Room (Indication and alarm)

Storage Tank w

plesel Generator Generator Output Control Hoos (Indication)

(voltoge, cur rent,

.sn f r ei}uency) neergency Power 400V ac buses (status)

Control Roan (Indicating Lights and System Voltmeter )

2400V ac buses (status)

Control Room (Anuseter and Voltmeter) 125V dc buses (status)

Air pressure Control Room (Indication and alarm) e4 N

A0 0

6 E

i TER C5257-310 4.

SPECIFIC RESIDUAI, HEAT REMOVAL AND C':EER FICUIRDENTS CF BPA}CH TICENICAL PCSI'" ION 5-1 3 ranch Technical Position 5-1 contains the Tunctional requirenents discussed in Section 3 and the detailed requirenents applied to specific systens or areas of operation. Each requirement is presented below along with a description of the Yankee Powe system or component applicable to the requirement.

4.1 RER Isolation Recuirements Recuirement The following shall be provided in the suction side of the RER system to isolate it fran the RCS.

1.

Isolation shall he provided by at least two power-cperated valves in series. The valve positions shall be indicated in the control roon.

2.

The valves shall have independent diverse interlocks to prevent the

?

valves fran being opened unless the RCS pressure is below the RER systen design pressure. Failure of a power supply shall not cause any valve to change position.

3.

O.e valves shall have independent diverse intericc'es to protect against ene or both valves being cpen during an RCS increase above the design pressure of the RER systen.

Evaluatien n

1.

"'he Yankee Rcw shutdewn cooling systen (SCS) sucticn line has two pcwer-cperated isolation valve 2 which do not have position indication in the centrol recm.

2.

Neither of the two SCS suction valves are provided with *open per:sissive" interlocas. The opening of these valves is administratively centrolled. The c=ntrols for the valves are located in the pri=ary auxiliary building (P AB). Key lock switches control each MCV, and the key is in the custody of the shif t supervisor.

The two sucticn valves, mv 552 and mv 554, are pcwered fran MCC 1, aus fl.

A f ailure of pcwer supply will net ef fect the position of these valves (either cpen-to-close or close-to-cpen).

3.

Neither of the two SCS suction valves are provided with "autoclosu' e

• r interlocxs. The SCS pressure is controlled ty the RCS pressure and

• The SCS functions at the residual heat removal (RHR) system at Yankee Rowe.

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TER-C5257-310 SCS (LPST) pump performance when the two systens are connected. M

' ensure that the SCS is not overpressured, the RCS overpressure protection system, which includes, the SCS relief valves, is provided. This is discussed further in Section 4.2.

The reaff has concluded that the deviations regarding the independent diverse interlocks 'for the SCS isolation valves that prevent cpening uritil pressure has decreased below SCS design should be corrected. The staff's position on these deviations is given in Section 3.2.

The deviation fran the BTP regarding lack of autanatic closure for SCS isolation valves is acceptable because of the combination of adminstrative controls and alar:ns provided on the SCS system. These alaens provide additional assurance that the operator action recuired by procedure will be taken to shut the isolation valves when RCS pressure is increasing toward'SCS design pressure.

The staff has concluded that the deviations regarding SCS isolation valve i

position indicatien in the control roan should be corrected. The staff's position on these deviations is given in Section 5.2.

Recuirement Cne of the following shall be provided on the discharge side cf the RER system to isolate it frcm the RCS:

1.

The valves, position indicators, and interlocks described in Secticn 4.1.

2.

One cc mcre check valves in series with a normally closed power-cperated valve. The power-cperated valve position shall be indicated in.he control rocm. If the RER systen discharge line is used for an ICCS function, the pcuer-operated valve is to be opened

'~

upon receipt cf a safety injectica signal once. the reacter coolant pressure has decreased below the ICCS design pressure.

3.

• hree check valves in series, or 1

4.

• wo check valves in series, provided that there are design provisions to permit periodic testing of the check valves for leaktightness and the testing is performed at least annually.

4 Rese B-61

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i TER-C5257-310 1

Evaluation The Yankee Rowe SCS has two motor-operated isolation valves in series on che systen discharge. The position of these valves is not indicated in the control room.

Like the two SCS suction MCys d,iscussed in Section 4.1, neither SCS

~

discharge.TV control circuitry is provided with an "open permissive" or

" auto-closure" interlock. The opening / closing of these valves is administrative 1y controlled. The controls for these valves are adjacent to the controls for the suction valves. Like the SCS suction MCv control

' switches, these are key lock switches with the key under the control of the shif t supervisor.

The two SCS discharge valves, McV-551 and 553, are powered frem MCC 1 Bus t

fl.

A f ailure of this power srpply will not aff ect the position of these valve s (either open-to-close or cic,se-to-open).

4.2 Pressure Relief Recuirements - Overpressure ?retection Recuirement To protect the RER systen against accidental' overpressurization when it 9

is in operation (not isolated fecm the RCS), pressure relief in the RER system shall be provided with relieving capacity in accordance with the ASME Soiler and Pressure Vessel Code. The nest ihniting pressure transient during the plant cperating cendition when the RER system is not isolated from the RCS shall be considered when selecting the pressure relieving capacity of the RER For example, during shutdown cooling in a PWR with no steam bubble in systen.

the pressurizer, inadvertent cperation of an additional charging pump or in' advertent cpening of an 2::CS accunulater valve should be censidered in selection of the design bases.

Evaluation All cperating PWRs have been required to nodify plant operating procedures and install the necessary hardware to ensure that the RCS when in a Ocid and shutdcwn conditien is not overpressurized.

• he RCS Icw tenperature 4

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1 l

TER-C5257-310 overpressure protection systen (LTCPS) must be capable of mitigating the most limiting mass and energy input events. The L". CPS will also afford protection for the shutdown cooling systen (SCS), which at Yankee Powe is the ecuivalent of the RER system.

The RCS and SCS can be connected whenever RCS temperature is below 330*F and the RCS pressure is below about 300 psig. There are no interlocks associated with the two sucticn or two discharge MCvs, and their pcaition is under administrative control. The SCS design pressure is 425 psig, and the systen has two spring-loaded safety valves set to open at 425 psig.*

The RCS low temperature overpressure pectection system is designed to prevent ea,:eeding the 10CTR50 Appendix G (isothermal curve) limit during the design basis mass and energy input events. The LTCPS utilizes the two SCS safety valves and the pressuriger solenoid-cperated relief valve (SCRV) with a manually enabled low pressure setpoint of 5C0 psig. By procedure, the SCRV is switched to the low setpoint when the RCS pressure has decreased to below 450 psig.

The LTOPS, while being specifically designed to maintain the RCS pressure within the Appendix G limits, is available for overpressure p'rctection of the SCS.

Each credible mass and energy input event is listed in Table 4.2-1 along with the peak RCS (hence SCS) pressure. In a Septemcer 14, 1979 (S] safety evaluatien the staff reviewed the Yankee Ecwe L CPS.

Information concerning j

mass and ener,y input events as well as additional discussien of the Is: CPS equipment, its enployment, testing, and associated technical specifications are further discussed in the staff's evaluation.

The SCS design limit of 440 psia is based on the pressure limit fer the bellows seals empicyed in certain system valves. If the bellows failed, the va'1ve stem packing would be subject to systen pressure, and even if the packing itself f ailed, the SCS w:uld not experience total loss of function.

The governing standard for the allowable pressure en the pipes and ether major components of the SCS is leerican Standard ASA 331.1, 1955. This standard allows the imposed stress.cf 115 percent of design during 10 percent of the cperating period and 120 percent of design during 1 percent of the operating M

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B-63 A Cruesen of "he Fransen IReemme

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I TA13I4 4.2-1 IllOPS ENERGY AND MASS ADDITION EVENTS y..

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,1 Peak 8L 5' I/ LOPS Single Pressure Nk Heat inlaut Source itCS Temperature I.ines of Defense Failure (psig) i~

Energy Add!Llon Events l

9 j

Core decay heat T<300*F 1 SVI + SORV 1 SV 515 j

and HCP (thermal) t All heatera T<300*F 2 SV + SORV 1 SV 470 i

MCP startup TRCS = 50' AT = 100*F 2 SVs

• SORV 2 SVs3 513 j

(Note 2) i 7

THCS = 100* AT = 100*F 2 Sva + SORV 2 SVs3 520 THCS = 100* AT = 100* F 2 SVs + SORV SORV 452 3

THCS = 150* AT = 100*F 2 SVs 4 SORY 2 SVs3 531 THCS = 200* AT = 100*F 2 SVs + SORV 2 SVs3 538 TECS = 100* AT = 150*F 2 SVs + SORV 2 SVs3 536

}

is assumed initially unavailable since an SCS MOV closure o

i 1.

Note is Osie SV is assumed to in!titate the event. The closure of an SCS 9

suction MOV makes the SCS suction side SV unavailable.

d Y

2.

Note 2s The AT Indicated la the differential temperature between the U

steam generator secondary water and the coldest water anywhere i!

s.

In the hCS, o

j 3.

Note 3: Tlie I.lcensee's analyses,rusumed only the availab!!!ty of the SORV, and took no credit for the SCS SVs.

The statf has found no failure which would disable both SCS SVs.

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TER-C5257-310 period.* The Licensee states thet Stone and Webster (AE for Yankee Bowe) specifications for the F.S are based en these ASA 331.1 requirements. These specifications are given below.

System Temeerature Allowable Pressure **

300*F 680 pelg 200*F 700 psig 1GO*F 720 psig Since these limits are not exceeded during any of the pcstulated transients given above, the staff concludes that the SCS piping and major conponents are adequately pectected for the LTCPS design base transients. The relief protection used, however, is not in accordance with the ASME ccde since an active ccanpenent (SORV) is utilized. The staff does not consider this a significant deviation and concludes that the overall SCS pressure relief requirements of BTP 5-1 are met.

This evaluation of SCS overpressure protection also applies to the low pressure surge tank (L75T) cooling locp since the LPST loep design is identical to the SCS.

Pecuireent Fluid discharged through tne RER system pressure relief valves must be collected and contained such that a stuck-cpen relief valve will not:

1.

result in flooding of any safety-related equipment 2.

reduce the capability of the ECCS belcw that needed to mitigate the consequences of a postulated LOCA 3.

result in a nonisolable situation in which the water provided in the RCS to maintain the core in a safe conditien-is discharged cutside of the contai:nent.

ASA 331.1, 19 55, paragraph 123 (b).

• • It should be noted that these pressures are above the allevable pressures (at comparable temperatures) required by Appendix G (isothermal curve) for the RCS.

M B-66 du Franniin Research C. enter

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i TIR-C5257-310 Evaluation 1.

The SCS relief valves (2) can discha:ge to either the icw pressure surge tank (LPST) or to the primary d:ain collecting tank (PDCT).

'During SCS operation, the SCS relief valve discharge is valved di:ectly to the LPST. A common 6-inch (CD) header directs relief l

discharge from several sources to two eductors under water. The LPST l

3 has a capacity of 750 f t,.and a level control system keeps the tank about half full. The tank and water level control is designed to take three pressurizer steam volumes before tank pressure :eaches 75 psig. The LPST has six safety valves which relieve to a common header. The header has a rupture disc which cpens at 25 psig and relieves directly to containment.

If one of the SCS :elief valves stuck cpen, then appecximately 101 gpm* would be lost out the RCS (and SCS) system. In about 29 minutes, the LPST would overflow cut the open rupture disc.**

In this situation, the following alacns would alert the operator: LPST level and pressure downstream of LPST safety valves.. Since there is no safety-related equipment in the containnent sump or en the centainnent floor where the LPST safeties and rupture disc would relieve, no flooding of ECCS-related equipnent would occur.

2.

The SCS is not used during either the injection or the recirculation phases following 'a LOCA. Therefore, a stuck-cpan 003 relief valve does not reduce 'the capability of the ICCS equipment.

3.

The SCS relief valves are outside containment but relieve to the LPST, which relieves back inside the vapor centainer DTC) : there f o re,

en a stuck-cpen SCS relief, there is no net less of RCS cr ECCS fluid.

Recuirement If intericeks are provided to automatically close the isolation valves when the RCS pressure exceeds the RER systen design pressure, adequate :elief capacity shall be provided during the tkne period while the valves are closing.

Evaluatien

~

As discussed in Sections 4.1 and 4.2, the SCS isolatien valves (two e

suction valves and two discharge valves) a:e not furnished with auto closure l

f eature s.

Therefere, this requi:ement is not applicable.

1

• 101 gym at 465 psig (110% of setpcint pressure).

• • The saf ety valves and rupture disc would open in about 15 min.

t

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M d' U Franxtin Research Center B-67 aon

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TER-CS257-310 l

4.3 Pumo Protection Pacuirenents Requirement The design and operating procedures of an RER systen shall have provisions to prevent danage to the RER systen pumps due to overheating, cavitation, or loss of adequate pump suction fluid.

Evaluation There are no autcznatic trip or other features associated with the SCS or LPST cooling pumps that are designed to protect these pumps from overheating, cavitation, or loss of adequate pump suction fluid. The 480-V breakers supplying power to the SCS and LPST cooling pumps are equipped with the following protective devices:

l 1.

inverse time magnetic overcurrent trip (adjustable from 60-160% of

~

100 amps coil rating) s 2.

instantaneous trip (5-12 times the overcurrent coil rating of 100 amps).

These features are designed to protect the power supplie's frem an equipnent f ault, but under certain ciretznstances (e.g, overheating), the trips may protect the pump motors. The Licensee has not evaluated these features with respect to cavitation, overheating, er loss of suction fluid.

The following indications could alert the cperator (s) to an abnormal situatien in the SCS:

1.

.MOV-554, -552, Position Indication 2.

Mov-551, -553, Position Indication 3.

LPST level 4.

LPST pressure 5.

SCS inlet tenperature 6.

SCS or LPST pump discharge pressure 7.

SCS or LPST cooler temperature (discharge) 8.

SCS discharge (to RCS) flow 9.

SCS or LPST cooler centrol valve (TICV 200) position.

A J$Enklin Researen Center B-68 w.n%vm m

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TIR-C5257-310 4.4

• est Recuireents Recuirement ne isolation valve operability and interleck circuits must be designed so as to permit on-line testing when cperating in the RER mode. Testability shall meet the requirements of 22I Standar d 338 and Regulatory Guide 1.22.

The precperational and initial startup test program shall be in confermance with Pegulatory Guide 1.68.

The programs for PWRs shall include tests with supporting analysis to (a) condirm that adequate mixing of berated water added prior to or during cooldown can be achieved under natural circulatien conditions and pe:mit estimation of the times required to achieve such mixing, and (b) confirm that the cocidown under natural circulatien conditions e.En be achieved within the limits specified in the energency cperating precedures. Canparison with performance of previously tested plants of similar design may be substituted for these tests.

I'valu atien

-he procedure used to test the operability of SCS isolat, ion valves

.TV-551 through -554 requires the stepping of the SCS pump prior to cycling the valves. Alternately, the operability of these valves could be checked by transferring SCS cooling requirenents to the Icw pressure surge tank cooling syste (f eed and bleed). Since there are no "Open pe: missive" interlocks associated with any of the four MCvs (two suction valves and two discharge valve s ), it is net necessary to bypass intericeks.

Yankee Bewe has conducted plant cocidowns using RCS natural circulation, but has not performed any tests regarding flow measurement, cecidewn rates, er ocren mixing. However, the staff believes that, with the beric acid cencentrations used for snutdown, adequate bcron mixing will occur under natural circulation flow.

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i TER-C5257-310 4.5 coerational Procedures Recuirement The operational precedures for bringing the plant from normal cperating power to cold shutdown shall be in conformance with Regulatory Guide 1.33.

f Pbr pressurized water reacters, the ' operational procedures shall include 1

specific procedures and info =sation required for cooldown under natural l

circulatien conditions.

Evaluatien The Licensee has procedures to perform safe shutdown operaticas including shutdown to hot standby, cperation at hot standby, het shutdown, cperation at het shutdown, and cold shutdown including long-term decay heat removal. The Licensee has also provided its operating staff with procedures for shutting l

down the reactor and fer decay heat removal under abnormal and emergency i

conditions. These procedures describe operator action in the event of less of system or parts of systen. functions normally needed for shutdown and ecoling the core. Procedures fer the operatien of individual systems used in safely shutting down the reactar are also included in the plant cperating peccedures. These procedures were reviewed and are in conformance with Regulatery Guide 1.33.

In addition, Section 8, " Procedures," of the Licensee's Technical Specifications assures establishnent of written procedures in acccedance with NRC standards and Paquiatory Guides (including Regulatory Guide 1.33).

l 4.6 Auxiliarv Feedweer Scrolv Escu irement The seisnic Gategcry I water supply for the auxiliary feedvater system..

for a PWR shall have sufficient inventory co permit cperation at hot shutdewn f

fer at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, follcwed by cocidown te 3e ccnditiens permitting operation of the RER system. The inventory neet d for cooldown shall be based on the longest cocidewn time with either en1}

r. t :e or enly offsite pcwer available with an asst:ned single f ailure.

B-70

.4 Franidin Resesre.n Center

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t TER-C5257-310 Evaluation The :nain coolant systen cooldown rates and auxiliary feedwater supply inventories under varying conditions are discussed in Section 3.2 and Appendix 3, Part 2.

6 9

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TER-c5257-310 5.

RESCLUT CN OF SEP 'ICPICS The SEP topics associated with safe shutdown have been identified in the introduction to this assessnent. The following discussions evaluate the degree to which the safety objectives of these tcpics are fulfilled at the Yankee Powe plant.

5.1 Toeic V-10.5 - RRR Svsten Reliability The safety objective of this topic is to ensure reliable plant shutdown capability using safety-grade equipment subject to the guidelines of SRP 5.4.7 and 3:7 RSB 5-1.

The Yankee Rowe PWR systens have been conpared with the criteria of BTP 5-1, and the results of.these canparisons are discussed in Sections 3 and 4 of this assessment. Section 3 discusses the way the functional requirenents are met and Section 4 discusses the shutdown cooling systen (SCS), which performs the function identified in BTP RSB 5-1 as residual heat renoval.

Redundancy to the SCS is provided by the low pressure surge tank (LPST) system. The LPST systen is physically arranged in parallel with the SCS. The conponents (pump and heat exchanger) of both the LPST systen and SCS are identical and share a cc: mon suction and discharge line in the shutdown cooling mode. Both the suction and discharge lines are isolated by two motor-operated valves in series. The staff finds this degree of redundancy acceptable; however, the following deviations exist which could i:npair the reliability of the system 1.

The SCS suction and discharge motor-operated isolation valves do not have position indication in the control reem. -The valves are operated from the primary auxiliary buildir.g. (PAB) and connet be operated fran the control rean.

2.

There are no provisiens to prevent danage to the SCS pump cr LPST systen cooling pump due to overheating, cavitation, or loss of adequate suctica fluid.

3.

In order to cool the reactor coolant systen to the SCS initiation point,and to initiate SCS operation, significant operator action must be performed from outside the control room.

ef'"Eiib

_B-72.

.;.3 Frarudin Research Center 4on

. m.r-a.a

TER <:5257-310 The first deviation as it relates to the potential overpressuri=ation of

)

the SCS or RCS is addressed under Tcpic V-ll. A.

The first two deviations also relate to interrupting the operation of the SCS while the plant is shut down and being maintained at a temperature. equal j

to or less than 330*F and at a pressure less than 300 psig. The consequences l

I of an inadvertent valve closure or pump failure are that the cocidown would terminate and the plant would start to heat up.

Installation of valve position indicaters and pump protective trips would alert the operator of the l

abnormal condition but would not preclude it fran occurring. Other plant parameters that are monitcred centinously in the control room are available to indicate the status of the cooldown to the operator. In the event that the cooldewn has been terminated due to a pump failure, the redundant pump and heat exchanger fran the L75T system can 'be put into service.

l Two modes of plant status :nust be censidered when evaluating the overall effects of a less of the SCS function and the acceptability of the deviations:

(1) plant shutdown with the temperature being maintained at less than 330*F and at sone pressure greater than atmospheric but less than 300 3

psig (2) the plant shut dcwn and cooled down to less than 20'0*F, the reactor vessel head removed, and the systen pressure at atmospheric.

l In the first case, if the SCS were disabled due to a pump failure, a second pump, fran the LP.ST system, would be available for continued cocidown.

If the disruptien of SCS were due to valve problems, an alternate :nethod of maintaining the cooldewn would have to be employed. Cne such method would be

]

to let the plant heat up and to remove the heat generated through the steam generators (feed to the steam generators can be cetained from a variety of sources). This provides an acceptable method in which 'to restere the heat renoval fran the primary system. In.he second case, "as defined above, if shutdcwn cooling were interrupted due to valving failures, adequate cooling cf the reactor :culd be accanplished by keeping the core covered with water.

Based en the discussiens above, the staff concludes that, although deviations f:an current licensing practice exist, the Yankee Powe SCS can reliably perfeen its cooldewn functions in the unlikely event of a penp er B-73

..W.-ranklin Research Center aom w niaien sm

)=

v I

1 TER-C5257-310 valve f ailure, acceptable alternatives exist to maintain *.he plant in a f

condition which will not endanger the public health and safety.

i The third deviation relates to the amount of operator action required to f-establish shutdown cooling. Branch Technical Position 5-1 states,that"a i

limited anount of operator action fran outside the control roaa 'is per:nissible. In the case of Yankee Powe, substantial effort is required of l

4 the operators from outside the control roaa to decrease main coolant temperature and pressure to a point where the SCS can be placed in operation.

j Most of the equipment that requires manipulation for cooldown is located and centrolled from outside the Yankee Bowe centrol roan. The staf f evaluation shows the time available before any operator action is necessary to be on the ceder of 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or scre, i.e., without any operator action, from inside or outside the control roan, the f acility can sustain itself with the water j

inventory at hand.

1

• The amount of operater action required is not caspatible with the intent of the topic criteria. The staff will consider the need for increased control roan cperability of cooldown systens during the integrated assessoent.

.c 5.2 Teoic V-11. A - Pecuirements for Isolatien of Hieh and Ecw Pressure f

Systens and "tcic V-ll.B - RF.R Interlock Pacuirements The saf ety cbjective of these tepics is to assure that adequate measures are taken to protect low pressure systems connected to the primary systen from being subjected to excessive pressure, which could cause failures and in sane 1

plants could cause a '.4CA outside containnent. The current criteria for RER i

i isolation and pressure relief are discussed in Sections 4.1 and 4.2.

i k

The Yankee Pcwe SCS suction and discharge (isolation) valves do not have any cpen per:nissive interlocks or autanatic closure features, and valve

~

position indication is not provided in the control roan. This deviation b

involves violating a pressure boundary between a high pressure systen (RCS) and a low pressure systen (SCS or LPST). The interlock and autanatic closure features are required whenever the RCS is at a pressure greater than the I

design pressure of the SCS or LPST (300 psig). The scst limiting case is when f

the RCS is at cperating tenperature and pressure. The SCS/IPST is isolated O

B-74

.d FranMn Researc.h Center 4:n e m a

TER-CS 257-310 l

l l

frcze the RCS at both the suction and discharge sides by two key-locked motor-l cperated valves in series. An inadvertent cpening of the pair of suction or l

discharge valves could cause overpressurization of the low pressure system, 1

which could cause a pipe or system failure, thereby creating a loss of coolant l

accident (LOCA) outside containnent. Current criteria require open permissive interlocks, which prevent opening th'e valves when a specific pressure diff erential exists across the valves. In lieu of the cpen permissive interlock, Yankee Powe has key-cperated valves, cperated locally in the primary auxiliary building, with the keys maintained under administrative

, control. Due to the potential severity cf SCS overpressurization, the Licensee will be required to provide (1) interlocks to prevent opening of SCS I

isolatien valves until the main coolant system pressure is below SCS design pressure and (2) valve position indicatien for the isolation valves in the

[

control rects, r

I The SCS isolatien valves do not have autcmatic closure interlocks to L

close the valves during slow increases in RCS pressure. *his is to prevent J

RCS pressuriration with any SCS isolation valves in the open position. Rapid increases in RCS pressure are discussed in the Section 4.2 evaluation of the

)

i low tenperature overpressure protection (L%P) sy st em.

Sc:se of these rapid pressure increases occur sufficiently fast that an autcrnatic closure interlock would not respend in time to prevent everpressuriration of the SCS. Ecwever, the staff concluded that the LTCP prevides acceptable SCS and LPST cooling locp pressure relief for these rapid transients. The staff has determined that the installation of autcmatic closure interlocxs wculd not be desirable since two of the three LOP relief valves are on the SCS, and autcmatic isolation of the SCS frem the RCS wculd render the L"CP system incperable.

Ecwever, in the SIP integrated assessment the staf f will evaluate the pctential need for additional measures, such as control recra valve indications, to prevent RCS startup and pressuriratien with any SCS isolation valves in the open pcsition.

42 B-75

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TER-C5257-310 5.3

• coic VM Svstens Facuired for Saf e Shutdown The sa:w/ objectives of this topic are:

1.

to assure the design adequacy of the safe shutdown s" tem to (a) initiate autcanatically the operation of appropriate systmas, including the reactivity control systens, such that specified acceptable fuel design limits are not exceeded as a :esult of anticipated operational occur:ences er postulated accidents, and (b) initiate the operation of systens and ccanpenents required to bring the plant to a saf e shutdown 2.

to assure that the regsired systens and equipment, including necessary inst:tsmentation and centrols to maintain the unit in a safe condition during hot shutdown, are located at appropriate locations outside the centrol roon and have a potential capability for subsequent cold st.atdown of the reacter through the use of suitable procedures 3.

to assure that only safety grade equipment is requi:ed for a PWR plant to bring the reactor coolant systen f:cza a high pressure condition to a low pressure cooling condition.

Saf ety objective 1(a) will be resolved in SIP Design Basis Event reviews. These reviews w'ill deter:nine the need for autcanatic. initiatien of p

safe shutdown systens to :nitigate the consequences of accidents and transients.

h Cbjective 1(b) relates to centrol room availability of the centrol and inst:umentation systens needed to initiate the operation of safe shutdown systens and assures that the cent:ol and inst:umentation systems in the control : con are capable of following the plant shutdown f:cra its initiation to its conclusien at cold shutdown condi:icnst this dcas not apply to *.*ankee 3cwe, since the entire cperatien of shutdewn cooling is performed outside the control recin.

g Saf ety cejective 2 requires the capability to shut down to both hot shutdewn and cold shutdewn conditions using systens, instruoentation and centrols located outside the centrol recm. Yankee Bowe has procedures which identify several methods of tripping the plant and methods to cooldown, p: ovide adequate instruction for determining the cperability and eendition of the essential plant equipment, and indicate the surveillance instrumentation and inst:uctions needed for interpreting the information.

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TER-C5257-310

' The review team visited each designated cperator station and assessed the capability cf the plant staff to perform the necessary cperations. The staff concludes that the plant can perform these shutdown operations.

Conformance to safety objective 3 was not evaluated but will be canpleted in part under SIP Tepic III-1, " Classification of Structures, C$mponents, and Systems (Seisnic and Quality)," and in part under Design Basis Event reviews.

5.4.Tesie x - Auxiliarv Teed Svsten (AFS)

The safety objective for this topic is to assure that the AFS can provide ad~ equate cooling water for decay heat renoval in the event of loss of all :nain feedwater using the guidelines et SRP 10.4.9 and BTP ASB 10-1.

The ESFP systen and backup method w'ere compared with SRP 10.4.9 and BTP ASB 10-1 with the following cenclusions:

i 1.

The Yankee Powe Nuclear Plant including the AFS will be reevaluated l

during the SEP with regard to internally and externally generated missiles, pipe whip and jet imping enent, quality and seismic design l

requirements, and earthquakes, toendoes, and floods.

2.

The AFS confcens to General Design Criteria (GDC) 45

(" Inspection of Cooling Water Systens") and GDC 46 (" Testing of Cooling Water Systens"). CDC 5 (" Sharing of Struc.ures, Systems, and Components")

is not applicable.

3.

The Yankee Pcwe AFS is not autanatically initiated.

The need tn provide for autanatic AFS initiation in accordance with Imssons i

Learned Task Force reconmendations are under staf f review.

I L

4.

The Yankee Pcwe AFS dcas not have capability to autanatically terminate feedwater flow to a depressurized steam generater and provide "Icw to the intact steam generater. This is acccinplished by local, manual valve operation. The ef fect of this deviatien will be assessed in he main steen line break evaluatien for the plant.

5.

In 1967, the Licensee made modifications to the Yankee Powe plant to prevent the occurrence of f eed syste:n waterharmner. The staff is centinuing its evaluation of feed systen waterhammer en a generic basis. SEP Tepic V-13, *Waterhammer," applies.

6.

The technical specifications for the AFS will be reevaluated against current requirenents under SEP Topic XVI, " Technical Specifications."

O R

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6.

REFERENCES l

1.

Staff Discussion of Fif teen Technical Issues in Attachnent to November 3,1976 Memorandun frem Director, NRR, to NPR Staf f, NUREG-0138, November 1976.

2.

Appendix A to Part 50 of the Cdde of Federal Pegulations, Title 10.

3.

L. H. Heider (YAEC)

Letter to Office of Nuclear Peactor Pegulatien (NPC)

Subj ect: Core XV Refueling.

26 March 1981 4.

E. McKenna (NRC)

Telephone Conversation with B. Jcnes (YAIC)

Subject:

Safe Shutdown for Yankee Powe.

27 March 1981 5.

D. E. Moody (YAEC) f.

Letter to D. G. Eisenhut (NBC)

Subj ect: NRC Pequirenents for Auxiliary Feedwater Systas at Yankee Powe Nuclear Power Station.

21 December 1980 6.

J. A. Kay (YAIC)

Letter to D. L.

ienann (NRC)

Su bj ec t: Resolution of "MI ' Category A" ::nplernentation Audit Cutstanding Itens.

9 April 1980 7.

L. H. Heider (YAIC)

Letter to H. R. Denton (NRC)

Subj ect: Ccmpliance with Appendix R to 10CFR50.

19 March 1981 8.

D. L. Zienann (NRC)

Letter to R. H. Grece (YA2C)

Subj ect: Anenchent No. 59 to Facility operating License No. :PR-3 for the Yankee Nuclear Pcwer Statien (Yankee Powe).

14 Septenber 1979.

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TER*:5257-310 APPENDIX 3, PART 2 i

SAFE SHt7:'DCWN WATI3 REQUIRIMENTS I

Introduction Standard Saview Plan (SRP) 5.4.,7, "Re sidual Heat Removal (P.MR) Syst em, "

and Branch Technical Position (BTP) RSS 5-1, Rev.1, " Design Requirements of the Besidct1 Heat Remeval Systen," are the current criteria used in the Systenatic Evaluation Program (SEP) evaluation of systens required for safe shutdewn. BTP RSB 5-1 Section A.4 states that the saf e shutdown system shall be capable of bringing the reactor to a cold shutdewn condition, with only of fsite or ensite power avdilable, within a reasonable period of time following shutdown, assuming the mest limiting single f ailure. STP RSB 5-1 Section G, which applies specifically to the anount of auxiliary feed systua lAFS) water of a pressurired water reactor available for staan generator feeding, requires the seisnic Category I water supply for the AFS to have sufficient inventory to per: nit operation at hot shutdown for at least four hours, followed by cocidown to the conditions permitting operation of the RER I

sy stem. The inventory needed for cooldown shall be based on 'ce longest cooldewn time needed wita either enly ensite er only ef fsite power available with a'n assumed single failure. A reasonable period of time to achieve cold shutdown conditiens, as stated in SRP 5.4.7 Section III.5, is 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

For a reactor plant cooldown, water is the mediu:n for transfer of heat frem the plant to the environs. Two modes of heat removal are available. The i

first mede involves the use of reactor plant heat to boil water and the venting of the resulting steam to the atmosphere. The water for this peccess is typically denineralired ";cre" water stored ensite and, therefore, is limited in quantity.

he systens designed to use this mode of heat removal (boiloff) are the steam generators for a pressurired water reactor (PWR) and the energency (isolation) condenser for a boiling water reacto'r (EWR). The second heat reeval mode (blowdcwn) involves the use of power-cperated relief valves to cuneve neat in the fccm of staan energy directly frem the reacter cooltnt syst en.

Since it is not acceptable to vent the reactor coolant systen directly to the, atmosynere, the stean is typically ver._,d to the contair:nent B-79

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building, f:an which contairusent cooling water systems transfer the heat to an ultimate heat sink - usually a river, lake, or ocean. When the blowdown mode is used, reacter coolant system makeup water must be centinuously supplied to keep the :eacter core covered with coolant to compensate for the loss'of coolant inventory. Systens employing the blowdown heat :encval mode have been designed into or backfitted onto scat 3WRs. The efficacy of the blowdown mode for PhAs has received inc: eased staff attention since the *hres.w.ile Island Unit 2 accident in March 1979. Additional studies are planned or in progress.

This evaluation of cooling water requirements for safe shutdown and cocidown is based on the use of the systen identified in the SIP Review of

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Safe Shutdown Systems which has been completed for each SEP f acility in acccedance with SRP 5.4.7 and BTP RSB 5-1 criteria. It should be noted that the SIP Cesign Basis Events (DBE) reviews, now in progress, may :equire the

cse of systens other than those evaluated in this :eport for reactor plant I

shutdown and cooldewn. In those cases, the water : equi:enents for safe shutdewn will have to be evaluated using the assumptions of the OBE review.

Oiscussion

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1 The :equirement in STP RSB 5-1 and SRP 5.4.7 that a plant achieve cold shutdown conditions within appecximately 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> is based mainly en the desire to be able to activate the MR systen and :ansfer the plant heat *o an ultimate heat sink prior to the exhaustion of the limited enount of onsite-stored pu:e water available for the ?JS cf a PWR.

A sustained het shutdewn condition, with reacter coolant systens temperature and pressu:e in excess of PER initiation limits, requires centinued boiling of f cf pure water

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to :enove reacter core decay heat. A 3WR :elying en the energency condenser systen for cocidewn under similar conditions would also pctentially exhaust onsite-stored pu:e water.

• water stored ensite is depleted, raw water, for exanple froen a river, lake, er ocean, can usually be tapped to supply the boileff systens. Ecwever, raw water can accelerate the cer:osien of boiloff systen materials in the steam generater and energency condenser tubes even if the water is fresn. Raw O

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TER-C5257-310 fresh wate-can cause caustic stre=s corrosion cracking of both stainless steel and inconal tubes in less than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> through NaCE concentration.

Seawater can cause chloride stress corrosion cracking of the tubes well with one week. Plant cooldown and depressurization would help reduce the rate of tube cracking by reducing the stresses in the tube materials and would also reduce the leakage : ate of reactor coolant through c:acks that de occur.

The original design criteria for the SEP f acilities did not require the ability to achieve cold shutdown conditions. For these plants, and for the mahority of operating plants, saf e shutdown was defined as hot shutdown.

Therefore, the design of the systems used to achieve a cold shutdown condition was detecnined by the reactor plant vendor and was not necessarily based en saf ety concerns. Safe shutdown :eviews yave pointed out a difference an vender approach to system design for cold shutdown :eflected in the Standard "echnical Specification definition of cold shutdcwns for a SWR, cold shutdown requires reacter coolant temperature to be J212*F; for a PWR, the temperature is j200*F. This difference in cold shutdown temperatures requires additional syst9ms for PWR cooling not needed for a 3WR.

For example, a BWR could use isolatien condenser alone to reach 212*F- (although the approach to the final temperature would be asymptotic); but a PWR, in addition to the steam generaters, must use RER and supporting systems to cool to 200*F.

Evaluation Taele i provides plant-specific data and assumptiens used in the staf f calculation of safe shutdown water requirements fo: the Yankee Rcwe nuclear i

plant. Tatie 2 presents tne results of the calculatien.

Tcur hours af ter the :eactor trip, the decay heat :ste is 1.774 x 10 Stu/h, and the integrated heat ove: the 4-hour peried'is 1.149 x 10 3tu.

To maintain a constant :eacter coolant taspe:ature of $38*F fer the 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, the staff calculated that 12,270 gallens of auxiliary feedwate: are requi:ed t

to remove the integrated heat. Following a 4-hour delay period, steam is released through five steam vent paths:

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TER-C5257-310 1.

atmospheric dump valve (ADV) 2.

1-in vent 3.

large hogger 4.

small hogger 5.

energency boiler feed pump (EBFP).

Assuming that the cooldown rate does not exceed the administrative limit of 50*F/h and that no single failure event occurs, cocidown to 330*F requires an additional 44 hours5.092593e-4 days <br />0.0122 hours <br />7.275132e-5 weeks <br />1.6742e-5 months <br /> and consumes an additional 59,700 gallons of makeup water. Final cooldown to 200*F is accmplished by manually actuating the

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shutdown cooling system.

Based on the staff calculation, Yankee aowe's existing stean vent paths do not have sufficient heat renoval capacity to achieve cold shutdown conditions within the Standard Review Plan 5.4.7 requirement of 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> assuming loss of offsite power and a single failure. However, sufficient l

va.ter inventcry is available to conduct the plant cooldown.

In a March 26, 1981 letter (3), the Licensee proposed changes to provide l

autmatic quick closure of the four main stean line non-return valves. This modification necessitated the installation of a new steam supply line to the stean-driven emergency feedwater pump and installation of additional staan dump capacity. During a March 27, 1981 discussion (4), the Licensee indicated that an additional manually cperated dump valve would be installed on each stema line upstrean of the non-return valve. Each of these valves is to have the ability to re:nove approximately 60,000 lbn/h.

"he staff repeated the saf e shutdown water requirenent calculation for these new stems vent paths assuning i

a single failure of one atmospheric dump valve. Table 3 presents the results of the calculation.

i As in the previcus case, the decay heat rate 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> following the reacter trip is 1.774 x 10 5tu/h and the integrated heat over the 4-hour 0

period is 1.149 x 10 Stu.

A total of 12,270 gallons of auxiliary feedwater is expended to renove the integrated heat. Steam is then. vented through the three at:nospheric dung valves. Assuming that the cooldown rate dees not exceed the ad:ninistrative limit of 50*F/h, cooldown to 330*F requires an additional 4.35 hours4.050926e-4 days <br />0.00972 hours <br />5.787037e-5 weeks <br />1.33175e-5 months <br /> and consumes an additional 7,320 gallcns of makeup I

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TER-C5257-310 water. Based on the above calculations, Yankee acwe's preposed stema vent paths have sufficient capacity to conduct a plant cocidown in accordance with 4

BTP RSB 5-1.

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i Table E.2-1 PLANT-SP!CIFIC DATA AND COCLDOWN ASST 3PTICNS I

Plant-Seecfic Cata-Plant Yankee Bowe Power 600.Wg Initial RCS Temperature 538*F Secondary Makeup Water Temperature 100*F Denineralized Water Onsite 85,000 gal Existing Atmospheric Dump valve 1.316 x 107 Btu /h at 935 psig Heat Panoval Capacity Proposed At:nospheric Cump Valve 2.025 x 103 Btu /h at 935 psig Heat Panoval Capacity - 3 Valves Large and Small Hogger Heat 6.415 x 106 Btu /h ar 935 psig Removal Capacity I

i Cne Inch Vent He.it Renoval 4.249 x 107 Btiu/h at 935 psig Capacity Energency Boiler Feed Pump Heat 2.388 x 106 Btu /h at 935 psig f

Removal Capacity h

cooldewn Assumotions 1.

Peactor trips at t = 0.

2.

Decay heat is in accordance with Draf t ANS-5.1.

3.

Plant renains at hot shutdown for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> prior to cocidown.

4.

Mass of water in the stema generator is constant.

5.

Ad:ninistrative cooldown rate of 50*F/h is not exceeded.

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Table 3.2-7 CAICU:,ATICN CF SAFE SE'JTDCWN WATER REQUIREMEN"5 Plant:

Yankee Powe (Calculaticns perfor:ned using the existing steam vent paths).

Phase I (Peacter trip to point at which decay heat generation equals the i

heat removal rate of the steam vent paths) 1 l

Time at which decay heat generatien equals heat removal rate:

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Phase !!

(Four-hour delay prior to cooldown):

8 Cecay heat generated prior to cooldewn: 1.149 x 10. ggu Feed' rater expended prior to cocidewn: 12,270 gal i

Phase !!!

(Cooldewn) :

Main Coolant Stean Generater fime th )

Teneerature (*?)

Pressure (esia)

Cecav Heat Ge ner at ed (3tu) 3 4.0 538.00 946.7 1.149 x 10 6.0 437.97 373.7

1. 490 x 10 0

3.0 337.87 214.9 1.804 'x 10 10.0 368.79 170.8 2.091 x 10 0

15.0 350.48 135.5 2.716 x 10 0

20.0 343.48 123.6 3.291 x 10 0

25.0 338.93 116.3 3.796 x 10 0

30.0 336,87 113.2 4.292 x 10 0

35.0 334.96 110.3 4.772 x 10 40.0 333.05 107.4 5.236 x 10 3~

45.0 331.14 104.7 5.685 x 10 3

41.0 329.99 103.0 5.946 x 10 6

Decay heat r ate at t = 48.0 h:

3.622 x 10 Stu/h Feedwater expendud during cocidewn to 330*F: 59,700 gal Tetal f eedwater expended: 71,970 gal i

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4 TER-C5257-310 Table 3.2-3 CALC'77.ATICN CF SAFE SHUTDOWN WATER REQUIREMENTS Plants Yankee Powe (Calculatiens perfccmed using the proposed steam vent paths)

Phase I (Feacter trip to point at which decay heat generaticn egaals the heat removal rate of the p, reposed steam vent paths):

Time at which decay heat generation equals heat removal rate:

0.0 min Phase II (Four delay prior to cooldown):

Cecay heat generated prior to cooldewn: 1.149 x 108 Stu Feedwater expended prict to cooldewn: 12,270 gal Phase III (Cooldown)

Time (h )

Temeerature (*?)

Pressure (psia)

Decav Heat Generated (Btu) 4.0 538.0 946.7 1.149 x 10 6.0 438.0 373.8 1.490 x 10 0

8.0 339.47 117.2 1.804 x 10 8.35 329.96 103.0 1.856 x 10 Cocay heat rate at t = 3.35 ha 1.477 x 10 Stu/h Feedwater expended during cooldewn to 330*F: 7,320 gal Total feedwater expended: 19,590 gal B-86

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y YANKEE R0WE SAFE SHUTDOWN SYSTEMS REVIEW CONCLUSIONS 1.

The staff concludes that the current

• auxiliary feedwater system does not meet the functional requirements of BTP RSB 5-1 but that proposed modifi-

. cations as described would satisfy the functional requirements of BTP RSB 5-1, except that the electrical components are not automatically powered from diesel-supplied electrical buses, although they can be manually con-nected. TMI Task Action item II.E.1.1 is further evaluating the relia-bility of the auxiliary feedwater system. The staff will consider this subject during the integrated assessment.

2.

The staff concludes that the shutdown cooling system (SCS), the component cooling water system (CCWS), the service water system (SWS), and the chemical and volume control system (CVCS) satisfy the functional require-ments of BTP RSB 5-1, except that the electrical components are not power-ed from diesel-supplied electrical buses.

The staff will evaluate the significance of this in the~SEP integrated assessment of Yankee Rowe.

3.

The staff defers evaluation of the adequacy of the pressure control and relief system to satisfy BTP RSB 5-1 pending resolution of current staff reviews of applicable THI-2 action items and fire protection requirements.

The staff will determine the effect that the e mpletion of these reviews will have on the safe shutdown topic during the integrated assessment.

4.

The staff concludes that the control air system does not satisfy the functional requirements of BTP RSB 5-1 in that a reliable source of control air is not available and significant operator action outside the control room would therefore be required to effect a safe shutdown. The staff will evaluate the significance of this in the SEP integrated assessment of Yankee Rowe.

5.

The amount of operator action required to perform the cooldown to cold shutdown is not compatible with the intent of the topic criteria. The staff will consider the need for increased control room operability of cooldown systems during the integrated assessment.

6.

Due to the potential severity of SCS overpressurization, the staff will consider requiring the following during the integrated assessment:

(1) interlocks to prevent opening of SCS isolation valves until the main coolant system pressure is below SCS design pressure and (2) valve position indication for the isolation valves in the control room.

• Current denotes pre Core XV configuration.

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The staff has determined that the installation of automatic closure interlocks would not be desirable since two of the three low temperature overpressure protection (LTOP) relief valves are on the SCS, and automatic isolation of the SCS from the reactor coolant system (RCS) would render the LTOP system inop-era ble.

However, in the SEP integrated assessment the staff will evaluate the potential need for additional measures, such as control room valve indications, to prevent RCS startup and pressurization with any SCS isolation valves in the open position.

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