ML19332B040
| ML19332B040 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 08/27/1980 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19332B038 | List: |
| References | |
| TAC-7170, NUDOCS 8009190602 | |
| Download: ML19332B040 (18) | |
Text
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UNITED STATES J
, 5-g NUCLEAR REGULATORY COMMISSION s
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SAFETY EVALUATICN BY THE OFFICE OF NUCLEAR REACTCR REGULAT!ON RELATED TO AMENCMENT NO. 28 TO FACILITY CEERATING LICENSE NO. CPR.c6 DUQUESNE LIGHT CCMPANY CHIO EDISCN COMPANY PENNSYLVANI". ?CWER COMPANY BEAVER VALLEY PCWER STATION. UNIT NO. I COCKET 70. 50-334 Introduction By letter dated November 17, 1977, tne Duquesne Lign: Concany (the licensee) initiated the required actions to satisfy the c:ndittens and recuirements Of the Crder for Modification of License which war issued by the NRC on Septemcer 30, 1977. This letter and subsecuent corres:codence referenced in Acpendix 1 :o this Safety Evaluaticn wculd enange the Tecnnical Specifica-tiens to reflect changes to assure the adequacy of the Net Positive Suction Head (NPSH) of the Icw head safety injection and recirculation scray ;umes.
Background
NPSH and Centainment Pressure and Tencerature Analyses anna Station, Ouring the c0urse of the cperating license review cf the Ncrtn na: licensee reevaluated the net ;csitive sucticn head (NPSH) available to the rectruciation scray (RS) and icw netc saf ety injecti:n (LHSI) :umos cased on a more conservative centain. ment analysis. NPSH is :ne neac, cr potential enargy, available er required to f rce 3 given fi w into the imceller of a :umc. NPSH is affected by centainment ressure, sumo wa er vapce :ressure, decth cf sumo water and suction :1;ing resistance :: ficw.
The revised analysis incorpers:cd analytical techniques and assume-icns that were selected to minimi:e One containment :ressure anc maximi:e the cen:ainment sumo water temcerature. nerecy minimi:ing the :alculatec !PSH available to the ;umes; the other fac:crs, namely, cepth Of succ dater and suction aiping resistance to flew, have a lesser affect en the revised analysis.
As a result of the analysis, certain cesign mccifications ere fcund to :e necessary to assure the adequacy of the availacia NPSH !:r toth the 'tS and
' HSI pucts.
8009190(ao2
2-The Beaver Valley Power Staticn, Unit 1 is an cperating plant with a design similar to tha of North Anna. It was determined that in :he event of a major loss-of-c:clant accident, the vapor pressure of the water in the Beaver Valley centainment sump which is the source of water for the RS and LHSI pumps during the recirculation phase is higher than the original analyses had indicated. This situation can result in inadequate NPSH for the RS and LHSI pumos at specific times during the recirculation snase of icng :erm ccre ecoling and centainment ecoling.
By a letter da:ed Septercer 3,1977, the if censee proposed interim acdifica:icns of the R$ and.HSI systems and requested that the Beaver Valley ?cwer Sta: ten be permitted :] cperate with :ne ; reposed interim modifications until such time as cermanent modifications are cesigned and installed. Based on cur review of the inf:rmation proviced by the licensee, we fcund :nat the stove proccsed modifications -ere acceptable en an interim basis, and by Crder dated September 20, 1977, we concluded that until permanent mcdificatiens are imple-mented, cperation would not pose an undue threat to the health and safety cf the public.
By a letter dated November 17, 1977, as supplemented by letters referenced in A::acnment 1, the licensee submitted a rescrt, wnien resented: (1) preocsed cermanent modifications of the RS and LHSI systems; (2) the cen-tainment ?ressure and temcerature response analyses and asscciated NPSH availaole to the RS and LHSI ;umos; and (3) proposed mcdifications to :he Cuenen Scray systems and spray nozzles Oc support the NPSH modifica:icns.
NPSH and related modifications made to 3eaver Valley Uni: 1 are:
1.
Inside Recirculation Spray (IRS) System a.
Remove and plug all type 1HH301CO nc::les in :he s; ray neaders.
b.
Reclace with type 1713A nczzles as recuired and plug remaining ioles.
Install a 4-inch line from the QS line to the sumo suction c.
of :ne *RS and crifices to regulate 150 g;m 05 sisenarge to ecch sue:fcn.
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o
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4 5.
RWST Modifications Removal of mixing weir inside RWST.
a.
Installation of elbcws en QS sump suction lines b.
inside RWST.
' grade of level instrumentation to :revide incut :o
,nteci circuitry f0F automatic cut-back 00ntrol :y c.-
- 7 QS system.
d.
I1 crease the : tal volume to 447,100 gallons.
5.
Quench 5: ray System Modification Replace all 236 :ype IMM30100 s: ray nc::les 41:h 156 ty;e a.
1713A ncz:les and plug remaining holes.
Add pi:ing 1cco seal Oc QS ficw paths inside : ntainment b.
to One IRS and ORS sumo suctions.
Install a larger imcelier in each :S ;cmo Oc handle addi-icnal c.
flow.
Install a motor-c;eratec cut-cack valve On each 05 =umc d.
Install a ficw restricting crifice in ;aralle!
disenarge.
wi;h the cut-bacx valve to provide reduced flew f r suo-atmosoneric peak pressure centrol.
(1) ensure
~he basis for imolernenting the above modifica icns was c: restrictive LCCA f:r all E aceouate iccine removal for ne mes:
ensure Safety Feature cumo comoinatiens; (2) revice adequate spray ::
containment depressuri:ation fcr all pure c:moina:icns; and ',2) ensureThis has teen adecuate NPSH available for all LCCA :ransients.
(1) assure caustic sciuti:n reaching :ne s: ray ed y modifica:icns 00:
H ncz:les, (2) add caustic solution at a rate that will assare s; ray :
is within Ocunds of the licensing requirements f:r all centainment de-ressurf:stien transients, (3) acnieve maximum s: cay thermai effec:12e-S: ray (RS) Systems, (a) recuce aess f:r the Cuench and Recircula:icn
. PSH required f:r the LMS! by restricting maximum f t:w :enct:icns, arc (5) increase NPSH available f0r the RS Systems :y providing subc cled 1
water 23 OumD suC:icns.
r 3eaver Valley Unt: i :uring
'he aboss ocdifications are teing made ::
- ne cur ent Outage.
4 4
.4 5.
9WST Modificatiens 3.
Removal of mixing weir inside RWST.
b.
Installatten of elbews en OS sump suctica lines inside RWST.
c.
U; grade of ievel instrumentation to previce incut :c centrol circuitry f:r au Omatic cut-bacx Ontrol :y the OS system.
d.
!ncrease the Octal volume to 441,100 gall:ns.
5.
- uenen 5
- ray System Mcdification 3.
Replace all 236 ty;e !HH3CICC s: ray ncz:les wi-h 156 y:e 1713A ncz:les and plug remaining holes.
c.
Add oising Icco seal o OS ficw :atns inside :cntaincent c the :RS and CRS sume suctions.
Install a larger imoeller in eicn ;S ;ung to nancle acci:icnal i
c.
ficw.
i d.
Install a matcr-c:erated Out-back valve on each OS ;ume discnarge.
Install a flew restricting crifice in :arallel with :ne cut-cacx valve to provide recuced 'iew f:r suo-at cs:neric seak ;ressure c:ntrol.
The : asis f:r imclementing :ne accve modifications was (1) ensure acequate iodine removal for ne most restrictive LCCA fer all Engireered Safety Feature. uma ccmcinations; (2) provice adequate s: cay to ensure c
containment decressuri:stien f r all aume :: cinati:ns; and (3) ensure l
adequate NPSH available f r 311 LCCA transients. This has :een ac :ctlisn-ac :y accifications to: (1) assure caustic solutien reaching the s: ray 1cz:!as, (2) add caustic sclution at a rate that will assure s; ray :H ts witnin tcunes f the licensing recuirements f:r all contair. ment de-
- ressurt:stien transients, (3) acnieve maximum s: ray :nermal effecci se-aess for the Ouencn and Recirculati:n 5: ray (RS) Systems, (a) recuce "PSH recuired f:r the.dS: by restricting maximum fl:w : nci-icns, anc (5) increase NPSH available f:r One RS Systems ty providing succ:clec dater Oc ;uro sucti0ns.
The above accifications are :eing made to 3eaver Valley Uni-I curing the :urrent :u: age.
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4 J
I 3
Evaluation NPSH and Containment Analysis The calculated cressure in the centainment and temcerature of the water I
1 that accummulates in the centainment sumes are imocriant carameters, in regard to available NPSH. in determining the RS and LHSI. ; ump cper-These terms, in ccmcination witn the ; ump ability following a LOCA.
i static head and asscciated line 'riction icsses, estabitsn the j
availacle NPSH caring the transient.
2 l
The required 1PSH ay :e reduced by a reduction in the ;ume flow rate.
Alternately, ne NPSH available at a given flow rate may be increased c
f The injection i
by the injec:f on of cold water into the pump suc f on.
cf cold water icwers the dater teecerature at the : ump suction and,
- nerefore, icwers the vapor pressure of the water entering the pumc.
The licensee precosed to utilize both of the above methods to resc1ve 4
i f
this croblem.
3 Recirculation Scray Pumos i
In ceder to assure an adequate amount of NPSH for the RS sumes. :he if censee procesed to divert cold quench spray (QS) water from the QS neaders : cone hu the RS cumo suctions.
be diverted to each of the inside RS ;umes, and 300 gpm will :e diverted
- o eacn of the cu: side ;umes. The cold QS water injection will icwer :he i
water temperature at the pump suction and, thereby Icwer the vapor ;ressure l
Therefore, a 4-incn line leading fecm of the water entering the cumo.
each quench spray heacer will be ecuted to the suc f on side of each cf the RS ; ump cn the same safety train as the QS pump sucolying the water.
A flew restricting crifice will be installed in eacn line to ensure he ccrrect ficw. No active ecmpenents will be used. This creposed mcdifica-No recuction
- icn will allow the ; umps to perform as criginally specified.
in flew rate to increase the available NPSH is necessary.
L0w Wead Safety Infection Pumes The change in -he lov safety injection flew as needed in Order to mee:
- ne NPSH recuirements of the LHS! cumos. The ficw was ilmited by means This cnange resultea in a of a cavita:ing venturi and flow restric cr.Mcwever, the licensee has demcnstrated sitgnty lcwer safety injecticn flew.
that :nis flew is still higher than the value assumed in the LOCA analysis.
Centainmen: Analysis for Evaluation of NPSH l
The new containment response analysis submittec by the licensee te cetermine the containcent pressure and sumo dater temoerature rescense was cased en the
, fo11cwing.
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1
, 1 The analytical technique used to determine the distribution of mass and energy in the liquid and vaper regions of :ne centainment fc11cwing a LOCA can influence the containment pressure / temperature response. The pressure flash method and temperature flash method are the two currently used techniques.
For the NPSH analysis, the licensee used the pressure flash methcd whicn l
assumes that liquid being expelled frem the break flashes _ at the saturation i
temcerature corresponding to the containment total pressure. This maximi:es the temperature of the water entering the sump, and is, therefore, ccnservative.
Previcusly, the centainment analytical model for NPSH analysis assumed that the liquid flashes at the dew :oint temcerature of the containment i
atmosphere (temcerature flash nethed). The temperature flash method is typically used fer ;eak containment pressure calcula:icns.
i The pipe break effluent was assumed to be unif:rmly mixed with the ECCS j
injection water spilling from the break. This is an imocriant consicer-stion for :cstulated cold leg treaks and essentially increases :ne energy This assumotion coes qct affect NPSH caicula: tens transferred :o One sump.
for costulated Set leg creaks since the break effluent is alreacy uniformly
+
mi xed. Previcasly, fer the NPSH analysis of ;cstulated cold leg breaks, ECCS water w4s assumed to spill directly to :ne sump witncut mixing, wnien resulted in 'cwer calculated sump water temperatures.
The licensee conducted a numcer of sensitivity studies to identify the other assumotions that should be used to minimi:e the calculated available NPSH. We have reviewed the results cf. these sensitivity studies and conclude that the folicwing conservative assump icns will minimi:e the calcula:ed available NPSH.
4 (1) A spray thermal effectivenes of 100% was assumed.
1 (2) A Icw initial containment pressure and hign initial containment temoerature were assumed.
Sensitivity studies were also cene to identify the single fatiure, creak j
si:e and pi:e break location :na: will give -he icwest calculatec availa le NPSH for the RS and LHSI ;umcs. The results of :nese studies incicated that f:r the RS,: umps, a costulated not leg dcuole-ended ructure will result i
in the lowest available NPSH, and for the LMSI :umos a ;cstulatec ;umc suc ten ecuble-ended :ipe rupture will resul; in :ne icwest availa:1e NPSM.
The available NPSH fcr -he inside recirculation ;umos das calculated :
4 be 12.7 feet, the available NPSH for the cu: side recirculation Ocecs was calculated to be 12.0 feet and the available NPSH for the LHSI :umes was 4
calculated to be 12.1 feet. The minimum NPSH required are 3.3 feet f:r the RS ':umos and 10.5 feet for the LHSI pumps.
a We nave performed ocnfirmatcry analyses fer the Oi;e break locations tha the licensee has icentified as giving the icwest availacia NPSH fcr ne 3
w
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.~..n..
. pumps. For cur confirmatory analyses, we used CCNTEMPT (MCC26) c0ccuter te based On The code has been modified to ;ermit the analyses ::
code.
The results of cur analysis; i.e., the con-the pressure flash method.
tainment pressure and sump water temperature vertus time, are in good agreement with the licensee's results. We, therefore, conclude that ne licensee's NPSH analysis is acceptable.
Effects en Containment Cecressuri:ation In view of the system ncdifications that were fcund recessary to satisfy the NPSH requirements of the RS and LHSI pumps, the licensee also perf:rTed a sensitivity study to determine :he impact en the decressurization time used in performing the analysis of the radiological consecuences following The results indica:e tha: the a ;cstulated loss-of-ccolant accident.
containment will be depressuri:ed :o belcw atmospheric ;resure within an hour follcwing a LCCA.
We have reviewed the input parameters used by the licensee to ;erform the depressuri:ation analysis and concluded that the analysis wculd result in a reasonably conservative calculation cf the containment de-The if miting case for centainment decressuri:sti0n is
- ressuri
- 3:icn time.
a : ump suction dcuble-ended rupture with minimum engineered safety feature Oceraticn.
A cecressurization time of 3550 seconds was calculated, whien is less :han the One hcur used in perfccming the analysis of the raciological consequenses We have ;erf rmed a confirma: cry analysis f:r the limiting folicwing a LCCA.
The results of our analysis, i.e.,
case fcr containment depressuri:ation.
containment pressure and depressuri:ation time are in gced agreement dith
- ne licensee's results. Therefore, we conclude that ne licensee's contain-ment decressuri:stion analysis is accestable.
Cuencn Scray Sys:em Based en cur requests for information en the containment s: cay sys: ems and on cur discussions On this system, the licensee mccifiec several cuecen These modifications will Orovide addi icnal assurance spray cceconents.
that the :ctential consequences Of :he ;cstulated LCCA remain :e10w the guicetines of 10 CFR ?ar: 100. Sy controlling :ne volume ficw rate of :ne caustic solution, the :H cf containment s: ray and :ne recircula:icn wa:er in :ne sumo can be kept within acceptacle if mits. The criginal design of
- ne 3eaver '/ alley Unt: No.1 included a gravity feec system wnien fed the caustic solutten to :he bott:m of the RWST. A weir arrangement in the RWST wculd assure the caustic solution mixed peccerly di:n the : crated wa er.
The pr0cesec system dill feed the caus-ic soluticn directly to :ne cuencn s; ray :umes suction at a metered rate previded by ;csitive disclacement, chemical injection ;umos (CI?s).
- urcs to the enemical acci icn The licensee added fcur ;csitive disclacemen
- two eacn, in carallel, to eacn Of :ne
~ lines of the ;uench spray system:
^
- u -
1.
These will ensure that the quench spray will have two quench scray trains.
a ;H cf at least 3.5 while the chemical addi:1cn tank (CAT) is emptying.After thi The earliest the CAT can empty is 55 minutes.
The ifcensee ;1ans bcrated water from the refueling water s:crage tank.
3
- However, to _ shut off the quench spray during a LCCA after about 100 minutes.
the recirculatten spray system starts after 5 minutes, and when the CAT is eq3 tying at the maximum rate, the recirculation spray ;H is up to 1
after about 24-30 minutes.
closed the CAT takes abcut 110 minutes :o empty; and the quench spray H increases
- H is kept to 3 Or acove until well after
- he recirculaticn spray :
to 3.
The procesed Technical Specifica f ca changes include increased CAT OH, wnten will ensure that the final containment sump ;H will be at least 3.0.
The licensee's changes will improve the overall f odine scrubbing reliacility cf the containment spray additive sys: ems, and will ensure that at leas:
One This is l
s: ray of ;H 11 to 3 will be used at all times during an accicent.
consistent with the icdine scrubbing effectiveness of the containment spray Therefcre, the system assumed in the original Safety Evaluation Re crt.
calculated doses from a design basis accident will not increase tue to One prcposed changes.
The proposed system modifications to the quench spray system for ;csitive injet:f on of caustic solution required electrical, instrumentaticn, and centrol changes wnich have been reviewed by cur contracter, IG&G :anc, The discussion of the modifications and results of their review Inc.
Our subsequent review of the remaining have been_ incluced as Attachment !!.
items frem EGaG's revt ew are as fc11cws.
Thermal Overicad Protection - QS System the only new valves added c :ne enemical Our review has determined tha:
addition system fer which R.G.1.106, " Thermal Overicad Protection f r Electric Meters en MOVs," is apolicable are the flow cutback valves wnich These valves are were added to the disenarge of the Ouench Scray Pumes.
ncrmally caen 52; receive a containment isolation - Phase 3 signal o The mo:ce coerated :nermal coen and clese On a icw-Icw level in :ne R'4ST.
The licensee 9as overload will ce by:assed for both of these signals.
committed Oc installing the bypass scheme crice o :lant startup.
Testing - 05 System The licensee has committed to cevelcoing and implementing by :lan startuo Orccedures which 4111 institute the following administrative centrols Oc be used f 0r testing the chemical additi:n system.
l L.u_
i i (1) Procedures will require notifying personnel performing the test of a containment isolation - Phase 3 signal so :ney can res:cre the system to its normal emergency configuration.
(2) After completion of the test, procedures will require an independent verification of the valve lineup to ensure correct system configuration.
f These administrative controls provide assurance that the system dill be coerable during and after testing.
Automatic OS Ficw Reduction Actuation Instrumentaticn j
i the precosed revision to the logic for the actuation of the autcmatic Quench Scray ficw reduction reduces the total numcer of channels, :ne cnannels to trip and the minimum channels cperable to one per train.
The acolication of the single failure criterien in wnien :ne failure of one of the quenen spray cutback valves to function is bcunced by the single failure of a diesel generatcr or a quench spray pump.
Therefcre, the results of ne containment depressurization analysis are not invalidated by assuming
- nat the single active failure which occurs is a f ailure of the cu back valve I
to activate at the required time.
Technical Scecifications We have evaluated the prcccsed Technical Specifications and conclude : hat ney adecuately inccrperate the requirements for NPSH as evaluated herein.
In the cerformance of :he depressurization study, the licensee also propcsed to nodify Technical Specifica:icn Figures 3.5-1 and 3.5-2 and :ne Limited Condition for Oceration statement 3.5.1.5.
The staff has not ccmoleted the review of :hese precosed changes and since they are not required fcr resolution of One NPSH prcblem, :nese proposed changes will be adcressed by a secarate anc subsequent revi ew.
nvironmental Consideration
~
We have determined that the amendment does not autnerize a change in effluent tyces er Octal amcunts nce an increase in ;cwer level and will not result in any significant environmental imoact. Having made tnis cetermination,
- e have further concluded that the amendment involves an action anica is insignificant fecm the standcoint of environmental imoact and, ;ursuant 3
to 10 CFR 551.5(d)(4), that an environmental imcac statement ce nega:19e declaration and environmental impact aporaisal need not te crepared in connection with the issuance of this anendment.
i i
1 Cenclusion 4
We have concluded, based :n the considerattens discussed above, that: (1) because the amendment does not involve a significant increase in :ne proo-ability er consequences of accidents previcusly considered and dces not involve a significant decrease in a safety margin, the amendment dces n3t involve a significant hazards consideration, (2) there is reasonaale assurance that the health and safety of th? public will not be encangered by operation in the arcocsed manner, and (1) such activities will :e con-cucted in ecmoliance with the Cctrvnission's.egulations and the issuance of this amendment will not ce inimical to :ne ccmmon defense and security or to the health and safety of tne public.
Date: August 27, 1980 i
t i
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4 Attachment I i
References 1.
R. W. Reid to C. N. Gunn letter dated Septemcer 30, 1977 transmi::ed
" Order for Modificaticn of License."
2.
C. N. Ounn to R. W. Reid letter dated Novemcer 17, 1977 procesed permanent modifications to correct NPSH inadequacies, includes Technical Scecifications.
3.
A. Senwencer to C. N. Dunn letter da:ed Acril 5,1978 request fcr additicnal information.
4.
C. N. Cunn to A. Schwencer letter dated May 15, 1973 with ;artial response.
5.
C. N. Dunn to A. Schwencer letter dated Augus: 3,1973 cercleted request fcr additional informaticn.
6.
C. N. Dunn to A. Schwencer letter dated Septemcer 11, 1978 corrected analysis for NPSH acequacy.
7.
C. N. Dunn to A. Schwencer letter dated Octccer 24, 1979 transmi::ec mass and energy release data and revised Technical 5:ecifica:icns.
i 3.
C. N. Gunn to A. Schwencer letter dated Sectember 23, 1979 transmitted revisions to NPSH modificaticns and revised Tecnnical Scecifications.
i 9.
C. N. Dunn to A. Schwencer letter dated Oc:ccer 13, 1979 included revised Technical Specifications.
- 10. S. J. Wcolever to A. Schwencer letter da:ed Fecruary 27, 1980 :ransmi::ed revisiens to NPSH mcdifications and revised Technical Specifica:icns.
- 11. C. 1. Dunn to S. Varga letter dated May 22, 1980 transmi ted crawings j.
to SG&G.
- 12. C. N. Dunn to S. Varga letter dated July 3,1980 transmitted revisions to Technical S;ecifica:fons.
- 13. C. N. Dunn to S. Varga letter dated Augus: 5,1980 provicec acci icnal information on NPSH modifications.
- 14. S. J. Woolever to S. Varga letter dated August 11, 1980 transmit:ec revision to Technical Specifications.
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ATTACHMENT II ECC-EA-5174 June 1980 EI.ICTRICAL, INS"".CW.E!ON A.O C0h";"ACL TEA"URES l
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This is an informal report intended for use as a pre!!minary or wort!ng document DUPLICATE DOCUMENT 1
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