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MAR 2 41983
CS - AfS -D/fa/
Docket No. 50-309
Mr. John H. Garrity, Senior DirectorNuclear Engineering and LicensingMaine Yankee Atomic Power Company83 Edison DriveAugusta, Maine 04336
Dear Mr. Garrity:
SUBJECT: STATUS REPORT ON REVIEW OF AUXILIARY FEEDWATER SYSTEM NUREG-0737ITEM II.E.1.1.
Enclosure 1 to this letter is a Status Report covering our review ofyour submittals (listed in Enclosure 2) on the Maine Yankee auxiliary
i feedwater system.
The Maine Yankee Auxiliary Feedwater System (AFWS) has been reviewedpreviously for conformance with the applicable recomendations specifiedin NUREG-0635 (Reference 1). These recomendations were subsequently in-corporated into Item II.E.1.1 of NUP.EG-0737. Based on that review, weprepared a Safety Evaluation (SE), which was transmitted to the MaineYankee Atomic Power Company (NYAPCo) (Reference 2). The SE noted thatwe could not find the following items from NUREG-0635 to be acceptable
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either because the submittal was incomplete or the responses were un-satisfactory:
1. Short Term Recomendation 22. Additional Short Term Recomendation 13. Short Term Recommendation GS-54. Long Term Recomendation GL-25. Long Term Recommendation GL-36. Long Term Recornnendation 4, Part b, and7. Basis for AFW Flow Requirements
Subsequently, you provided further information for our review (References'
3, 4, and 5). We reviewed this information and find that your responsesto the recomendations of Additional Short Term Recomendation 1 (for pro-vision of redundant level indications and low level alarms for the primarywater source), and to Long Term Recomendation GL-2 (regarding single flowlines with single valves from the primary water source to the AFW pumps) areunsatisfactory. For.these recommendations we suggest that you provideadequate modifications to address our concerns as discussed in the enclosedStatus Report.
You should assure us that the lev'el alarms at 10,000 and 100,000 gallons c'
are or will be provided with power from separate Class IE power suppliesin order to guard against failure of both alarms in the event of failureof any one power suppiy . Tuu shuuit aisu giui.n.L .3.in=t the feU re of the
omce> .. single..va.1 ve...in...the..1. ire...from..the..prijnary... water..tource..to..the ADLE. tsp.4..in . , , . . , , , , , , , , .
SURNAME) aCCor.d.ance w i..t..h.. ..m..e..t. ho..d.ss..pe.ci.f..i e..d.. i..r Long T.erm Recomendation GL-2.. . - - - . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Mr. John Garrity: -2-
! In addition, you should provide further assurance that the event involvinga steam line break (Reference 5) does not require operator intervention
- to prevent "dryout" of the unaffected steam generators at a time earlier'. than can reasonably be achieved. This assurance is required to satisfy| our concern regarding the " Basis for AFW Flow Requirements" in the enclosed| Status Report.i
Furthermore, we find your response to the remaining incomplete items notedabove to be satisfactory with the stipulation that further information is
ito be satisfactory with the stipulation that further information is requiredfor clarification of some of the items as follows:'
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1. Short Term Recommendation 2 - You have verified that emergency pro-cedures include direction for manual control of auxiliary feedwatercontrol valves, as necessary. We recommend that Maine Yankee include
:manual control of pneumatic-operated valves in the steam admissionline to the turbine-driven AFW pump in the emergency procedures.
2. Long Term Recommendation GL-3 (including Short Term Recommendation GS-5) -You should reexamine the need to isolate the steam admission line to theturbine-driven AFW pump with respect to the need to operate the AFW system;
upon loss of all AC you should provide us with detailed results of this re-7 examination. You should also provide assurance that effective operation of
the AEW system can be maintained in the event of loss of. AC power as n'oted inthe section of the enclosed Status Report relating to GL-3.
The Instrumentation and Control Systems Branch (ICSB) has reviewed the followingitems discussed previously in Reference 2 and has issued a separate Safety
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Evaluation covering them which was transmitted to you by letter dated September 3,'
1982:1. Additional Short Term Recomendation 3 - ICSB has reviewed your design for
design for provision of safety-related auxiliary feedwater flow indicationto each steam generator and has found the design to be acceptable.
2. Long Term Recommendation GL-1 - ICSB has reviewed your design informationfor upgrading the control grade automatic AFW system initiation circuitryto safety-related and has found the design to be acceptable.
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In addition Reference 2 contained four items which were found acceptable pen-ding verification or later action. Comments regarding these items are notedbelow:
i 1. Short Term Recommendation GS-4 - GS-4 deals with emergency procedures tobe prepared for guidance of plant operators for transferring the AFW pumps'
to alternate water sources in the event the primary supply is unavailableor is being depleted. You committed to upgrade the plant procedures to'
provide instructions to operators for transferring to alternate sources.; We found your commitment satisfactory, pending verification by the Office
of Inspection and Enforcement (OIE) that the procedures were in place.i
The I&E inspector notified us by telephone that the procedures were in' place; therefore, we consider Item GS-4 closed.,
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SURNAME) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
onep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
NRc FORM 318 (10-80) NRCM 024o OFFICIAL RECORD COPY usc e _ m ua_ _ _ -
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John Garrity: -3-
Short Term Recommandation 1 - This recommendation required you to proposea revision to the Technical Specifications requiring monthly AFW system,
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operability testing in lieu of testing on a quarterly basis. Your proposedChange No. 677 Reference 6 in response to our requirements. We concluded4
that your response was acceptable pendin9 our approval of this change.;
Change No. 67 specified that components in ASME Classes 1, 2 and 3 be testedin accordance with the inservice inspection requirements of the ASME Boilerand Pressure Vessel Code; this required each pump to be tested every monthin accordance with the ASME code and addenda then in force. However, the
! frequency for pump testing was changed from one month to three months in the,
iaddendum to the ASME code issued in December 31, 1979 (Section IWP-3400).Therefore, your response is now found to be unacceptable. We recommend that
. you prepare a Technical Specification to provide for monthly surveillance ofAFW system operability in accordance with the provisions of Short Term Recom-
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mendation 1.
3. Long Term Recommendation 3 - Long Term Recommendation 3 required that you
|modify the design so that the power supplied to the three AFW control valves
' and one steam admission valve to the turbine-driven pump would be fromdifferent vital power supplies instead of one power supply (Division 4
i vital bus). You stated that a design change addressing this recommendationwould be implemented (Reference 6). In reference 10 you noted that the
!three AFW flow control valves had been modified by the installation of
|an additional solenoid to operate each valve with one solenoid receiving
| power from vital bus 1, the other solenoid receiving power from vital bus3. You further stated, that the steam admission valve to the turbine'
driven pump is normally powered from vital bus 41 power can be providedi
pfrom emergency bus 7 by means of a local selector switch. We find thisj a acceptable.t
| 4. Long Term Recommendation 4 - You should provide assurance that the plantcan respond adequately to a break in an AFW line. If operator intervention
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!is required, should provide summaries of plant procedures used for operator
j guidance in the evnet of a pipe break in the AFW system.| The Maine Yankee Technical Specifications (Section 3.8E) presently require only,
two motor operated auxiliary feed pumps to be operable. This is unsatisfactory,since the third turbine driven pump is permitted to be out indefinitely. Thiscould have serious consequences if the turbine-driven pump were allowed to be
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i inoperable indefinitely and a loss of all AC power event were to occur as therewould be no provision for providing water to the steam generators in order to
: cool the primary system. In addition, staff reliability studies (not specific:
|to the Maine Yankee Plant) have shown a significant increase in reliabilitywhen the inoperability of the third AFW pump is limited. It is noted that the,
current Standard Technical Specifications Reference 7 for plants with three!
AFW pumps '(two powered electrically, one powered by steam) permits plant opera-j
; tion for no more than 72 hours with one AFW pump inoperable.
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OFFICE ) . . . . . . . . . . . . . .. . . . .* ..
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DATE ) . . . . . . . . . .. .. .. . . . . . . . . . . . . . ., ,
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John Garrity -4-
Therefore, you should propose changes for the Maine Yankee TechnicalSpecifications similar to the Standard Technical Specifications whichrequire that the plant proceed to hot shutdown in the event that evenone AFW pump is inoperable in excess of 72 hours.
Because of the large number of unresolved items included in this StatusReport, we suggest the report, be a basis for meeting or teleconferenceswith our staff. Please contact the Maine Yankee Project Manager (Ken L.Heitner) and arrange for a suitable meeting or teleconference within 45days of your receipt of this letter. At that time you should be preparedto discuss your schedule for the completion of all items discussed herein.
We request that all submittals requested by this letter be submitted within120 days of your receipt of this letter.
A copy of our Status Report is enclosed.
Sincerely.
Orlinsi signed by:
I Robert A. Clark, ChiefOperating Reactors Branch #3Division of Licensing
Enclosure:1. Status Report DISTRIBUTION2. List of References'
pUocket FileLocal PDRORB #3 RdgD. EisenhutJHeltemesRAClark'
PKreutzer (3)| OELD
NSICE.L. Jordan
i J.M. Taylor (1)
| ACRS(10)KHeitner,
Gray File
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( .om- > ..ard.G.e.t. ..xHettner:.:dd3EAclarx. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
! oue> .3L#1.63.... . 31.2?I63....... .. 3i${lB3.. ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OFFICIAL RECORD COPY usam mi--ases0NRC F ORM 318 00-80) NRCM 0243. - _ . . _ _ . _ - . . - _ . _ _ - _ -_ . - . _ _ _ - _ - . . . - _ . _ _ _
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11aine Yankee Atomic Power Company"
cc: E. W. Thurlow, President Mr. Robert H. GroceMaine Yankee Atomic Power Company Senior Engineer - Lic'ensingEdison Drive Maine Yankee Atomic Power CompanyAugusta, Maine 04336 1671 Worcester Road
Framingham, Massachusetts 01701,
Mr. Donald E. VandenburghVice President - Engineering U. S. Environmental Protection AgencyYankee Atomic Electric Company Region I Office1671 Worcester Road ATTN: Reg. Radiation RepresentativeFramingham, Massachusetts 01701 JFK Federal Building
Bes;on, Massachusetts 02203John A. Ritsher, Esq.Ropes & Gray225 Franklin Street -Boston, Massachusetts 02110
State Planning ~0fficerExecutive Department189 State StreetAugusta, Maine 04330
Mr. E. C. Wood, Plant ManagerMaine Yankee Atomic Power CompanyP. O. Box 3270 .
Wiscasset, Maine 04578
Regional AdministratorU. S. Nuclear Regulatory CommissionRegion I631 Park AvenueKing of Prussia, Pennsylvania 19406
First Selectman of WiscassetMunicipal BuildingU. S. Route 1Wiscasset, Maine 04578
Mr. Paul Swetland'
Resident Inspector.c/o V. S. Nuclear Regulatory
CommissionP. O. Box EWiscasset, Maine 04578
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Mr. Charles B. BrinkmanManager - Washington Nuclear OperationsCombustion Engineering, Inc.7910 Woodmont Avenue
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Bethesda, Maryland 20814
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Enclosure l '. ...
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STATUS REPORTAUXILIARY FEEDWATER SYSTEM EVALUATION, NUREG-0737, ITEM II.E.1.1
MAINE YANKEE ATOMIC POWER STATION
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1. Short Tenn Recommendation 2 "The licensee did not submit sufficient infor-mation for us to conclude that all failures will result in opening thepneumatic-operated.AFW flow control valves and steam admission valves to theturbine used to impel the turbine driven AFW pump. We conclude that thelicensee should establish suitable emergency procedures for operation of .
the pneumatic-operated valves in the event that valves were to fail closeddue to an unanticipated failure mode of the comon AC bus." .
The licensee specified(I) that the Maine Yankee emergency procedures includedirection for manual control of feedwater control valves, if necessary.Further, the licensee noted that improvements to emergency procedures .in thisarea are continuing in response to Item I.C.1 of NUREG-0737 which required,
consideration of multiple and consequential failures.
We find the response acceptable pending verification by the licensee that theprocedures already available include control of all of the pneumaticallyoperated valves in.the steam admission line to the steam-turbine driven AFWpump, as necessary.
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2. Additional Short Term Recomendation 1 "The licensee should provide redundantlevel indications and low level alarms in the control room for the AFW systemprimary water supply, 'the demineralized water storage tank (DWST), to allowthe operator to anticipate the need to make up water or transfer to an alternatewater supply and prevent a low pump suction pressure condition from occurring.The low level setpoint should allow at least 20 minutes for operator action,
! assuming that the largest capacity AFW pump is operating."
Il) reported that the following instrumentation was available forThe licenseethe DWST:
_(1) A low level alann when the volume of water in the tankiis$riciuced 5..~_.._2. IOU 000.gaYjo'nf(Jjs.h'ouF,'ippy,Tf, iga ~tel) Z~~ '...
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(2) A low-low level alann at 10,000 gallons I(3'0'-iiinute suppl.y), ' . ~.T." I . I'.~
(3) Level ' indication at the control board, and
(4) Local level indicating gauge at the tank.
Both alarms are on the control board.
The licensee reported that, in addition to the instrumentation, the auxiliaryoperator records the level of water in the DWST twice each shift.
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In addition, the plant Technical Specihications require that at..least 100,000gallons of primary grade feedwater be available to allow the reactor"to be'maintained in a power operating conditio.n (Specification 3.8D) but do notspecify where thbse 100,000 gallons *are' stored.
We would find the plant to be in compliance with the criteria of Additiondl .s
Short Term Recomendation 1. if, in addition to the foregoing, the followingcriteria were met: i.,
(1) 'T6e' Tech'nical' Specifications should be.mo.dified..so ' hat.ti$ $0.000.g'al.lons ~~~
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~Tprim'ary ~ grade feed.wate.r. will_ ba provided_in the DWSL ". .[,,o
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The.licelse~e shoul'd[ pro'5d'e assu[ance3ai.'5be_100.00hTsal.1 fa15 mind T __ 1I~~ ~
(2) v
10,000 ij.de,suc.h. separat1 ort.allon alarm.ge powered frm.senarate_C.la.ss_1E_ power _suno11es. -.
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An altbrnative approach is the one first suggested, i.e., redundant alarms andlevel indications.
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Iri t'h'e ablence ofeitheE5f the above sugdestions.:ot an, acceptable a,1ferna'tive,' "-
- ~ ' ' ' - - - ~ ""we fiiid t'he 'l'icenseeM .resoonse to be unacceptable.', ,
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3. Short Term Recomendation GS-5 "The as-built plant should be capable ofproviding,the required AFW flow for at.least two hours from one AFW pump trainindependent of any ac power source. If manual AFW sys, tem initiation flow .control is required following a complete loss of ac power, em&rgency proceduresshould be established for manually initiating and controlling the system underthese conditions. Since the water for cooling the lube oil for the . turbine-driven pump bearings may be dependent on ac. power, design or procedural changesshall be made to eliminate this dependency as soon as practicable. Until thisis done, the emergency procedures should provide for an individual to bestationed at the turbine-driven pump in the event of the loss of all ac powerto monitor pump bearing and/or lube oil temperatures. If necess,ary, this operatorwould operate the turbine-driven pump in an on-off mode until ac power is1
I restored. Adequate lighting powered by direct current (de) power sources andcomunications at local stations should also be provided if manual initiation andcontrol. of the AFW system is needed (see Recomendation GL-3 for the longer-termresolution of this' concern)." -
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See response to Item GL-3, below. -
| 4. Long Term Recomendation GL-2 " Licensees with plants in which all (primary and| alternate) water supplies to the AFW system pass through valves in a single flow: path should install redundant parallel flow paths (piping and valves).| Licensees with plants in which the primary AFW system water supply passes
through valves in a single flow path, but the alternative AFW system waterf
! supplies connect to the AFW system pump suction piping downstream of the abovevalve (s) should install redundant valves parallel to the above* valve (s) or'
provide automatic opening of the valve (s) from the alternate water supply upon.
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low pump suction pressure. The licensee should propose Technical Specificationsto incorporate appropriate periodic inspections to verify the valve positions."
water storage tank (DWST)y for the.AFW system is provided from the' demineralizedThe preferred water suppl
with an alternate supply from the primary water *storage tank (PWST). All the water from the DWST passes through a single,linecontaining a single locked-open . valve after which.the line separates into threedifferent path.s,; each path leading to an auxiliary feedwater (AFW) pump.There are two parallel paths from the PWST to the suctions of the AFW pumps;one line leads to the suction of the two motor driven pumps while the other pathleads to the suction of the turbine-driven AFW pump. There are closed valves inthe paths from the PWST to the AFW pumps wilich have to be opened manually topermit water to flow from the PWST to the AFW pumps.
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In response to this recomendation hhe licensee statedO) that testing in !'
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accordance with Technical Specification 4.6B will verify the. adequacy of flowthrough the locked open valve,on a monthly basis. .However, we fin'd this *.junacceptable on two counts, as follows:
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; (1) In the test specified by the licensee (to be' conducted quartsrly as~ specified in the Technical Specification,' not monthly, as stated) each'
AFW pump takes' water from the DWST and pumps it back into the DWST. If'
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the flow rate is markedly lower than.,the nonnal AFW flow rate an almostcompletely closed valve may not be detected in the test,
(2) The test is periodic and accidental valve closing (as a result of humanerror; or mechanical valve failure) would not be detected in the periodbetween tests.
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| ..The approach contained in this recomendation..is intended.to. reduce the.. possibility.of damage to the AFW pumps from this source -- the single locked-open valve in & !'
single supply line. Our experience in conducting and reviewing AFW system'reliability studies.has shown that a single valve in a flow path is'a significant ~contributor to a reduction in system reliability. The licensee should propos'e~
one of the following three alternative solutions or an acceptable alternatiye;.as_. _- - - -
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--l .' t.uw svetion trip- Of 'al'T"AFW ptimps 17 it cEH Te shown th'at this wil'1 preventpump damage, . . _ _ . . .
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2. Removal of internals of the single valve in the single flow path, or ' 4
3. Locking open all valves from the secondary water supply (the.PWST) to all .iAFW pumps with ~ provisions in the Technical Specifications to require
maintenance of a suitable volume of water in the PWST. -
'The Ticensee shouid commit to a modification of the suction line design as~ -
, described above and should provide a. schedule for modifying and. implementing thedesign. The licensee should provide details of the modified design' for ourreview. We will report the resolution of this concern in a future _s. atus _ _ .. -..t
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5. Long Term Recommendation GL-3 "At least one AFW system pump and its associatedflow path and essential instrumentation should automatically initiate AFWsystem flow and be capable of being operated independently of any ac powersource for at least two hours. Conversion of de power to ac power is acceptable."
In response to the recomendation, the licensee reported that water for coolingboth the turbine bearings and the lube oil for the turbine-driven AFW pump isprovided by a tap off the pump discharge. There are three solenoid-controlled,air-operated valves in the steam admission line to the turbine: a containmentisolation valve, a pressure control valve and a turbine intercept valve; thelatter two are designed to fail open on 16ss of air or power while the con-tainment isolation valve is designed to close on loss of air or ac. Powerfor the isolation valve may be provided by the station battery through inverterson loss of ac or the valve may be operated manually. In addition, the air-
operated turbine governor has an independent air receiver which will pemitthe governor to maintain control for four hours.
Thus, the turbine-driven pump may be operatid for two hours following a, lossof all ac, as specified in the recomendation. This complies with thecriteria of GS-5. However, in response to the recomendation (GL-3) to auto-matically initiate AFW flow upon loss of all ac, the licensee notes that thecontainment isolation valve in the steam supply line would have to fail openon a loss of power in order to provide flow under all potential power failures.It was stated further that the licensee "...' considers the immediate need forcontainment isolation, when required, to be a more significant safety
.. consideration than the perceived need to automatically start the. turbinedriven pump."
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We do not consider that the licensee's basis for isolating the steam aoSfUionline in lieu of permitting automatic initiation of the AFW system upon loss ofall ac power is sufficiently justified to permit deviation from the course of
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action recommended in Long Term Recomendation GL-3.
We recommend that the licensee reexamine the need to isolate the steam admissionline upon loss of power and compare the need to isolate with the need toinitiate the AFW system in the event of loss of all AC. It appears thatstarting the AFW system would provide greater safety than would isolating the. steam line.on loss of all AC. It may 'also prove possible to preserve both func-tions by keeping the steam admission line open only upon loss of all AC. Thelicensee should provide us with the results of this examination.
In addition, the licensee should absure us that the level in the steam generators,. -
after_30_ minutes and prior to AFW initiation accounts for loss of steam generator - "
inventory in the event the steam generator blowdown sys_ tem _remajps__ogerable_ ..J.uning a..hss.of-ali-AC power.
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6. Long Term Recommendation 4 (part b) "In the event of a steam or feedwaterTine break (main or auxiliary), isolation of the auxiliary feedwater flow ~ ~
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path to the affected steam generator is accomplished manually. The licensee
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shou.1d evaluate these oostulated.oice breaks.and .(1) determine.any~ ' ~
AFW system design changes or procedures necessary to detect and isoli'tE thebreak and direct the required feedwater flow to the steam generator (s) beforethey boil dry or (2) describe how the plant can be brought to safe shutdowncondition by use of other systems which would be available following suchpostulated events." ,
Inresponse,thelicenseereported(2)thattheAFWsystemwould.bemodified(and verified that modification had been accomplished during the cycle 6 outage (3))as follows:
(1) Provision of automatic starting of the two motor-driven AFW pumps uponlow water level signal from any one of the three steam generators, .
(2) Modification of the auxiliary feedwater control valves so that eachcloses individually upon a low steam generator pressure signal. In theevent of a steam line break this will isolate the steam generator in thetrain which contains the ruptured piping, -
(3) Provision of a five-minute delay in initiation of the two motor-drivenAFW pumps (or tripping of the two motor driven pumps for five minutes if'already running) upon receipt of the steam generator low pressure signal.
Note that this design would require operator intervention to direct AFW flowto the undamaged steam generators if the control valve in the damaged steamgenerator were to fail and remain open after receipt of the EFCV signal, in
'- order to prevent steam generator "dryout" because most of the water from theAFW system would then be diverted to the damaged steam generator.
We find the conceptual design provided in the licensee's submittal acceptableand in compliance with the requirements of this recommendation with regard to 'a steam line or feedwater line break. The Instrumentation and Control SystemsBranch has reviewed the design for compliance with the guidance of long tennrecommendation GL-1 and has found the design to be in compliance with therequirements of GL-1. (4) The licensee, however, has not provided informationto assure us that an AFW line break can be properly isolated either bymodifying the AFW system or by operator intervention. If the AFW line breakis to be isolated by operator intervention the licensee must show that theplant operator can detect a break in an auxiliary feedwater line and respondrapidly enough either to prevent the steam generators from boiling dry or tobring the plant to safe shutdown by means of other available systems. Thelicensee should provide a response to resolve this concern. This response <should include a summary of any plant procedures prepared for operatorguidance in the event of failure of an AFW system line and should confirm thecapability to prevent steam generator dryout or to bring the plant.to safeshutdown by alternate means.
7. Basis for AFW System Flow Requirement (Enclosure 2) "In Enclosure 2 to ourletter of October 18, 1979, we requested the licensee to provide certain
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infomation regarding the design basis for AFW flow requirements. Thelicensee stated in a letter dated November 20, 1979, that the required infor-mation would be submitted at a later date."
The licensee notedII) that the design basis events for the Maine Yankee AFW
system were those shown in Table 1, below.of Ine AFW system is the loss-of-main-feedwat'eF (LMFW)g event for the design~ The boundin
The lic'ensee rep 6rted.
that ' loss of all AC and feedw'a'ter line break were not .p. art of_ the ,sp. ectr.um .of design basis events for Maine Yankee.
Table ~1
1) Loss of Main Feedwater (LMFW) |
2) LMFW w/ loss of offsite .AC Power,
3) Turbine Trip with and without' bypass !
4) Main Steam Isolation valve closure , ,
5) Main Steam Line Break6) Small break LOCA
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In the event a LMFW event occurred, the licensee stated that the steam generatorswould dry out in 13 minutes with offsite power available and in 30 minutes withoffsite power unavailable assuming the AFW system did not start. Further, the
licensee noted that, in the event of a loss of all AC, the operator would have30 minutes in which to start the turbine driven AFW pump before steam generatordryout occurred. If a steam line break occurred with the present AFW systemdesign, operator action would be necessary to direct AFW flow away from thefaulted generator and to the intact one if the flow valve in the AFW train tothe faulted steam generator failed to close automatically, in order to preventdryout of the steam generators in the unaffected trains.(3) The licensee mustprovide further information to assure us that the operator has sufficient timeto act. .
The licensee reports that a single AFW pump is capable of removing the totalcombined. heat resulting from reactor coolant pump operation and decay heatseven minutes after the LOWF event begins. In addition, the minimum inventoryof 100,000 gallons of water available (discussed above in Additional Short TemRecomendation 1) to the AFW system in the DWST is sufficient to remove thecombined beat load (ge'nerated by reactor coolant pumps and decay heat) for atleast four hours -- eight hours if the reactor coolant pumps do not opera'te.
We find the licensee's design basis flow requirements for the AFW systemacceptable because the licensee has shown that the design flow rate is capable
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of mitigating those transients and accidents for which use of the AFW systemis necessary to assure a safe plant shutdown with the exception that assurancehas to be provided that operator action can be taken in a sufficiently shorttime in the event of a steam line break with failure of an isolation or flowcontrol valve in one of the AFW trains.
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References
1. Letter, from John B. Randazza, Maine Yankee Atomic Power Company, toRobert A. Clark, U. S. NRC, dated August 21, 1981.
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2. Letter, from Robert H. Groce, Maine Yankee Atomic Power Company toU. S. NRC (Attention: Robert A. Clark)Subject: "Feedwater and Auxiliary Feedwater Modifications," dated
April 28,1981.
3. Attachment to Letter from Robert H. Groce, Maine Yankee Atomic PowerCompany to U. S. NRC (Attention: Robert A. Clark)Subject: " Cycle 6 Steam Line Rupture Analysis,"_ dated October 29, 1981.
4. Memorandum, from T. P. Speis, AD/RS, DSI to G. Lainas, AD/OR, DL,Subject: " Safety Evaluation - Maine Yankee Auxiliary Feedwater
System Automatic Initiation and Flow Indication (TMIAction Plan Item II.E.1.2)," dated August 30, 1982.
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Enclosure 2 ,
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References :
1. NUREG-0635, " Generic Evaluation 'of Feedwater Transients and SmallBreak Loss-of-Coolant Accidents in Combustion Engineering DesignedOperating Plants."
2. Letter, from Robert A. Clark, U. S. NRC to ' Robert H. Groce, MaineYankee Atomic Power Company, dated April 30, 1981.
3. Letter, from John B. Randazza, Maine Yankee Atomic Power Company, toRobert A. Clark, U. S. NRC, dated August 21, 1981.
4. Attachment to Letter from Robert H. Groce, Maine Yankee Atomic Power -
Company to'U. S. NRC (Attention: . Robert A. Clark)Subject: " Cycle 6 Steam Line Rupture Analysis," dated October 29, 1981.
5. Letter, from Robert H.'Groce, Maine Yankee Atomic Power Company toU. S. NRC (Attention: Robert A. Clark)Subject: "Feedwater and Auxiliary Feedwater Modifications," datedApril 28, 1981.
6. Letter, from Donald E. Moody, Maine Yankee Atomic Power Company toDarrel G. Eisenhut, U. S. NRC, dated November 20, 1979.
7. NUREG-0212, " Standard Technical Specifications for Combustion EngineeringPressurized Water Reactors." (Revision 2)
8. Letter, from John H. Garrity, Maine Yankee Atomic Power Company toRobert A. Clark, U. S. NRC,Subject: Auxiliary Feedwater System Automatic Initiation and Flow
Indication (TMI Action Plan Item II.E.1.2)," dated January 4, *
1983.
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