ML17333B092

MAAP4 Analyses of DC Cook Containment Response to Small Break Loca.

ML17333B092
Person / Time
Site:	Cook
Issue date:	10/09/1997
From:	Henry R FAUSKE & ASSOCIATES, INC.
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ML17333B093	List: ML17333B092 ML17334B657
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NUDOCS 9710270156
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Attachment 2 to AEP:NRC:0900M FAUSKE AND ASSOCIATES'CTOBER 9, 1997 PRESENTATION svcoava~ss evxom PDR AOGCK 05000815 P PDR

4 ANAIVSKS OF 'AiE D.C. COOK CGNT NY RESPGNSE TG S54V L BREAK I QSS-GF-CGGI AWE ACCIDENTS R. E. Henry Pauske A Associates, Inc.

Presented to USNRC White Flint Gffices Rockville, Maryland Gctober 9, 1997

OVI'I INK Introduction to the MAAP4 computer code.

Benchmarking calculations for this effort.

Comparison of the containment pressure and ice melt rate with I.OTIC-3 for 6" and 2" cold leg breaks.

Comparison of the RCS break flow with the NOYRUMIP model for 6" and 2" cold leg

, breaks.

Comparison of RCS break Qow with a large break BSA calculation.

Comparison of the containment response given DSA mass and energy releases.

Comparison with the Westinghouse ice condenser experiments.

o Important input parameters and sensitivity studies for the B.C. Cook nuclear plant evaluations.

Results for postulated small break I GCAs at the B.C. Cook nuclear lant.

BASIS PGR INVIKSTIGATINGA SPECTRUM GF I GCA CONDITIONS A I OCA must be large enough for the containment sprays to be activated and needed over the long term.

For a large I OCA, the RCS will depressurize, I PI will be initiated and the core will be cooled with cold water leaving the RCS break location.

In this case, the containment sprays would only be required early in the accident.

The sensitivity calculations show that the utilization of containment sprays is the greatest for small I OCA conditions. The utilization of containment sprays is determined by the transient containment pressure including (a) the sprays turning on if the pressure increases to 2.9 psig and turned off at 1.5 psig, and (b) the sprays run continuously once they are activated. Both are evaluated.

IXIRODUCTIONTO 'IHE MWU'4 COMPVIER CODE EPRI owned code and used internationally.

Developed and maintained under a QA program in compliance with 10CFRSO, App. B.

MAAZ4is structurally organized as a modular code and includes models for:

the reactor core response (BWR 4 PWR),

the reactor coolant system response (BWR 4 PWR),

the steam generators (PWR),

the containment response (BWR 4 PWR),

the contributions of the emergency safeguard features (BWR & PWR), and the response of adjacent plant building (auxiliary building, etc) where appropriate (BWR 4 PWR) ..

As an integral system model, the focus of MAAP4 is on the total plant response to postulated accident conditions, with particular emphasis on accident management evaluations.

As an integral system model, the 1VQMP4 focus is on the best-estimate evaluations for all phenomena evaluated.

MD4V'4 Modular Accident Analysis Program M44U'4 is a modular computer program written in fortran and is directed at evaluating the integral response of the RCS, containment and ESFs to a broad spectrum of possible accident conditions.

The MMQ'4 code is fast running (variable timestep) and has been developed for:

PWRNSSS (B&W, CE, + K) designs large dry containments, subatmospheric containments, ice condenser containments.

BWR NSSS (ABB + GE) designs Mark I containments, Mark II containments, Mark ID containments.

CAZG)U NSSS designs Ontario Hydro containment designs with the vacuum building, AECL design with a separate containment for each reactor.

VVER NSSS designs reactor confinement including the bubble tower.

Fugen NSSS design single containment with a suppression pool.

HV(5100997.A

MMQ'4 Modular Accident Analysis Program (Continued)

MAIAP4 modeling includes:

Response to LOCA or inadequate cooling conditions.

Models for core degradation, core melt progression, debris quenching, etc. necessary to evaluate severe accident conditions.

A generalized containment model that promotes extensive containment nodalization if desired. This generalized containment is used for all containment types listed above.

M44&'4 contains a dynamic benchmarking capability that enables the best-estimate models to be benchmarked with available experiments and experience. These benchmarks can be easily repeated as the code evolves.

HV$ 100997-h

Steam Outlot (to turbino)

Steam Steam Outlet Generator (to turbine)

Feedwator Inlet (from con4onser)

Feedweter Inlet (from con4neer)

Main Coolant Pump Coro Reactor Voo@H 4 Loop Westinghouse Reactor Coolant System

Cohl Lee Cold Leg Steam Geneakr Tubes Peseurtzer~

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FlNIce 3-1 PNR primary iyitcm nodalizatiea for Ncstinghousc 4-loop design.

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MAJOR BENCHMARKS Current MAAP4 Dynamic Bench marks yster Creek loss-of-feedwater (BWR)

C rystal River loss-of-feedwater and stuck ope n PORV (PWR) each Bottom turbine trip tests (BWR) okai-2 turbine trip (BWR)

D avis-Besse loss-of-feedwater (PWR) rown's Ferry fire (BWR)

I-2 (RCS) Y (0-5 hrs.)

I-2 containment Y (0-5 hrs.)

HEBUS OFT-FP-2 ORA (BWR R PWR)

W ice condenser tests Ice condenser DB calculation W SG tests aterial creep COVE aerosol tests 0 RNL fission product release tests DEMONA aerosol tests ACE ACE experiments ETA experiments

4 CQMENC S KEPORTEB XN 'lKK GPEN LITERA'PURE S. J. Lee, et al., "Benchmark of the YKDR Ell.2 Containment Hydlrogen MHxing Expex iment Using the MVkAP4 Co@e," SUbBDttedl fox Novembex, I997 ANS meeting.

C. Y. PaRk, et al., "Validation Exercise fox the MIAA3P4 Containment Morsel," Hfth International Confex'ence on Simulation Methods in Nuclear Engineering, Montx eal, Canada, September S-II, I996.

H. Xixmka, et al., "An Analysis of Hydlrogen MUoa'mg andi Bistribution Px'oMem ISP-35 Using MA%F4 Code," PSA'95 Px oceedlings, November, I995.

BENC CAI CULATIGNS FQR THE D.C. CQGK SBI.QCA SUMP FJtI I EVALUATIGNS Containment pressure and ice melt comparison with I 0'rIC-3.

6" cold leg LOCA.

2" coM leg I OCA.

0 Yhe break Qow x'ate spectrum used in the MlAAP4 scopHlg calculathons compax'ed with the NOTRUMIP model.

6" coM leg LOCA.

2" cold l.eg I GCA.

Yhe break How x ate for a large break I OCA DSA condition.

The contamment xesponse given BSA mass and energy xeleases to containment.

Comparison of the MlAAP4 ice condensex model with the VYestinghouse experiments.

WHAT IS EXPECTED FRGM THE BENCHMAjRKCALCUI ATIGNS Assure consistency between "best estimate" and "design basis" analyses.

Assure consistency of the MAAP4 ice condenser model with the experimental basis large I GCA, medium I.GCA, small I GCA.

CGMtPAiRXSON VVXYHTIKE LOYLC-3 RESUI I' This compaxison is an ev"luation of the respective containment models.

The boundaxy conditions fox both evaluations axe the mass and energy x'eleases fxom a 6" and a 2" cold leg IOCA as calculated by NOYRlUMP.

Given the NGYRM4P mass and energy xeleases and the specification of the Cook containment, the x'esulting containment xesponse fox the tvvo models can be corn pax'ed.

D.G.GOOK 6-INCH LOC A MAAP4 (TEXITI F)

LOTIC-3 (NOMINAL ICE MELT) 0 0

TIME Comparison of the LOTIC-3 and MAAP4 ice depletion rate for a six-inch diameter cold let LOCA (NOTRUMP) for the D.C. Cook Unit 2.

D.C.COOK 6-lNCH LOCA MAAP4 (TEXITI~ )

LOTIG-3 (NOMINAL IGE MELT) ()

0 TIME Comparison of the calculated D.C. Cook Unit 2 containment pressure for LOTIC-3 and MAAP4. The RCS blowdown is common to each analysis and is calculated for a six-inch diameter cold leg break using NOTRUMP.

D.C. COOK 2-INCH LOCA MAAP4 (TEX)TI )

LOTIG-3 (NOMINAL ICE MELT) ()

T IME Comparison of the LOTIC-3 ice depletion rate for a two-inch diameter cold leg LOCA with the MAAP4 calculation using the same mass and energy inputs from the NOTRUMP calculation.

D.C. COOK 2-INCH LOCA

() MAAP4 (TEXITI )

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()) () 0 () < 0 ooo(xSr (N)()n'o(go cx()) 0 ()%) ((())(r)()()ar)( ~<)a~'Q$~()9 T IME A comparison of the LOTIC-3 containment pressure calculation, biased for maximum containment pressure, with the nominal MAAP4 calculation with the accident initiator being a two-inch diameter cold leg LOCA as represented by NOTRUMP.

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LONER COMPARTMENT MAAP4 (TEXITI= )

LOTIC-3 (NOMINAL ICE MELT)

TIME Comparison of the upper and lower containment compartment temperatures for a LOTIC-3 calculation biased for maximum containment pressure and the hQdd'4 representation with the accident initiator being a two-inch diameter cold leg LOCA as represented by NOTRUMP.

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0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 TIME SEC Comparison of the integrated mass releases for the MAAP4 and NOTRUMP for a two-inch cold leg LOCA.

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CD IIP P P I 0 WESTINGHOUSE ANAI.YSIS 0

0 0

0 0

0 00 0

0 0 0 O 0 O QIS0 0 0 0 00m 10 15 20 30 TIME SEC Comparison of the MAAP4 break flow rate for a large break LOCA with that used in D.C. Cook design basis analyses.

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Table Com arison Result

1. Comparison of the hQ~'4 containment Good comparison between the calculated model and the LOTIC-3 calculations for a ice consumption rates for both codes and six-inch cold leg LOCA. the transient containment pressure history.

2. Comparison of the MAAP4 containment Good comparison between the ice melting model and the LOTIC-3 code for a two- rate, as well as consistent representations inch cold leg LOCA. of the containment pressure history and the calculated temperature histories in the upper and lower compartments.

3. Comparison of the MAAP4 and Agreement between the integral mass and NOTRUMP mass and energy releases for energy releases to the containment.

a six-inch cold leg LOCA.

4. Comparison of the MAAP4 and Agreement between the integral mass and NOTRUMP mass and energy releases for energy releases to the containment a two-inch cold leg LOCA. atmosphere.

5. Comparison of the MAAP4 and large Agreement between the integral mass and break LOCA mass and energy releases. energy releases to the containment atmosphere.

6. Comparison of the MAAP4 containment Good agreement between the transient response with the design basis analysis. containment pressure and temperature histories in the upper and lower corn artments.

BENC G WITH 'HHE %lFSTINGHOUSE ICE CONDENSER EXPERIMENTS The Westinghouse ice condenser experiments have been run for a variety of break sizes.

These experiments were performed for a full scale segment of the ice condenser with an ice basket height that is three-fourths of the plant.

'he principal information from the experiments is the depressurization of the simulated RCS, the pressure in the containment lower compartment,.the pressure in the containment upper compartment, the temperatures of gases exiting the top of the ice condenser, the drain temperature of water leaving the ice condenser and the approximate ice melted.

It is important that the integral system model be consistent with the experiments since the ice melt rate is a major contribution to the integral containment response and is also an important component of the water inventory in the circulation sump.

MIAAJP dynamic benchmarks are being performed for three different break sizes investigated in these experiments which are generally representative of a large LOCA (Test A), a medium size LOCA (Test C) and a small LOCA (Test F), and decay heat steaming condition (Test K). These benchmarks are performed using the dynamic benchmarking capability in the MAAJP4 code.

IN ERHEOIATE OECX OOORS RECEIVER VESSEL LATTICE FRAIIES ICE BASKET BOILER VESSEL RUPTURE OISK ANO ORIFICE 0 ISCIIARGE PIPE OIVIOER OECK INLET OOORS TURNING VANES 0 ISCNARGE NOZZLE Isometric view of boiler and receiver vessels at the Waltz Milltest facility.

LOWER COMPARTMENT MAAP4 DATA UPPER COMPARTMENT MAAP<

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Comparison of the upper (solid lines) and lower compartment pressures (dashed lines) for the MAAP4 containment model with an ice condenser exit temperature of and the experimental data from Test A (large break LOCA) of the Westinghouse ice condenser experiments.

hlAAP4 Q MEASURED tCE BASS AT THE ENO OF THE EXPERIBEHT I

I CD RES y TIME (SECONDS)

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Cb CD Ql Cornparitson of the cakuhtion of ioe meIting for the MAAP4 nodd with an ice condenser exit temperature of P Ql and the end point. remaining ice mass for Test A (hrge bmdc LOCA).

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Comparison of the upper and lower compartment pressures for the MAAP4 model using an ice condenser exit temperature of with the measured behavior of Test C (medium LOCA).

SAAP4

'EASURED ICE BASS AT THE END OF TKE EXPERIBENT Pg 4'p TINE (SEGOIIIIDS)

~anon of the MA@% ice mdt history with aa ice amdeaser exit temperature of 'F with the measured ice at the cod of Test C (roedium LOCA).

LONER COMPARTMENT MAAPi TEST F OATA HIIIIIII/IlIIIIIIIIIlIlIIIIlIIIIllllllllslllllllllllllllllllllllllllIlIlllIIIIIlIIIIIIIIII[/J u

T IMl-Comparison of Test F pressure versus time for an ice condenser outlet temperature of

BAAP4 Q MEASURED ICE BASS AT THE END OF THE EXPEAIHEHT CD I

s45 I

CO cD CA CD TIME (SECONDS)

Comparison of the calculated remauung ice mass and the ead point mamuemait for Test F.

LONE fl COMP AH TMENT DATA MAAP<

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CD I C1J I LCC I OL I CL I I

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Comparison of the measured lcnver compartment pnssure for the long term decay heat removal experiment (Test K) and the MAAP4 containment model using an ice condenser exit temperature of

MAAP<

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CD VI CX TIME (SE G 0 NO 8)

CD VI Calculated ice mass melting history for Test K using an ice condenser exit temperature of VI iI

CONCI USIONS WITH RESPECT TO TAHE BENC G ACTIVITIES The comparison of the MAAP4 containment model and LOTIC-3 for the 2" and 6" cold leg LOCA show good agreement between the ice melt rate and the transient containment pressure history with LOTIC-3 having a somewhat higher ice melt rate and higher containment pressure consistent with the design basis philosophy of the code.

The integral break flow and energy flow considered by M4VdP4 are in agreement with the flow rates from NOTRUMP. Also, the spectrum of LOCAs considered in the M44V'4 analysis span those which are to be investigated by the BSA codes.

Comparisons of the MAAP4 best-estimate model with the full scale experiments show a consistent response of the containment with the measured behavior. This is true for both the containment pressure response and the ice melt conditions.

The composite of these benchmarking activities shows a consistent representation of the containment response for the best-estimate scoping model (MAdd'4) and the design basis calculations (NOTRDHP and LOTIC-3).

Furthermore, the best-estimate model is consistent with the results of the large scale experiments used to characterize the response of an ice condenser containment to variety of LOCA conditions.

SENSITIVITY S'I UBIES FGR THjK CGGK NUCLEAR PLAlVX SUMP FILL EVALUATIONS Yhe most important sensitivity calculation is to consider a variety of break sizes. In this regard, the MAAP4 sensitivity studies wil. investigate LGCAs from one-half inch to six inches in diameter. This encompasses the entire small LOCA range.

The particular issue of interest for this evaluation is the sump depth for the containment spray pumps. Consequently, the duration of the containment sprays is an important variable in this evaluation. Therefore, the variations in plant parameters, within tech spec limits, are assessed to determine the influence that these could have on the use of containment sprays. The Mluence of conditions whereby the sprays would be turned on at 2.9 psig and turned off at 1.5 psig or run continuously once they are activated will be evaluated.

Other plant parameters inAuence the mass of air in containment, the condensing capability of the sprays, etc. These will also be investigated in these sensitivity calculations.

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Lower Carta.iIiment Simplified Schematic 612'-0" (333,000 gallons) (337,000 gal excl. cavity) 610'-0" (276,000 gallons) (126,000 gal Inactive Sump Active Sunup Reactor (Pipe Annulus) 602'-10" (110,000 gallons)

Cavity 598'-9" Important levels and volumes for the active and inactive sumps.

Volume Descri tion Volume/Mass Available RWST Water Inventory 295,000 gal Available Ice Mass 2.43 x 10'bm (291,472 gal)

TOTAL 586,472 gal Accumulators 4 x 921 gal) ft'27,500 TOTALWI'MACCUMULATORS 613,972 al Volume Descri tion Volume/Mass Reactor Coolant System (including the pressurizer) 11, 159 gal) ft'83,469 Volume of the Pressurizer 1800 gal) ft'13,464 Approximate Inventory Needed to Keep RCS Full During Cool - 20,000 gal Down Inactive Sump Reference Water Volume 335,960 gal Net Volume for Water Accumulation in the Inactive Sump 319,000 gal Active Sump Reference Water Volume to the 602'10" Level 117,320 gal Net Volume for Water Accumulation in the Active Sump to the 116,000 gal 602'10" Mvel Water Volume for the Reactor Cavity 117,795 gal TOTAL 572 795 31

Table 4-3 Location Ma nitude of Water Holdu Water required to fillthe containment spray 7,789 gal and RHR piping but not the RHR spray lines.

Water in-flight during spray operation o

upper compartment (h = 80.2 ft), 267 gal

~ lower compartment (h = 50,9 ft), 93 gal

~ annular compartment (h = 36,75 ft). 13 gal Sprays impinging upon walls and draining as a film upper compartment (42,000 ft ), 206 gal lower compartment (15,000 ft'), 74 gal annular compartment (10,000 ft'). 49 gal TOTAL 8 491 al

OCCOOK 10 HOOE 6 COLO LEG LOCA SLO6 IO 10 30 60 0 IO 20 30 40 TIME HOURS TIME HOURS Io 20 30 o Io 10 30 40 TIME HOUR S TIME HOURS Summary of the containment system response for a six inch diameter cold leg LOCA.

DCCOOK Io RODE 3 COLD LEG LOCA SLOi tt I

CCC re CO CO ill vl D

IO 20 30 io 50 40 70 $0 90 100 IO 20 30 io 50 40 70 jo 90 IOO vs TIME HOURS TIME HOURS I

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ill CL CO Vl CCC ~

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' i0 IO 20 30 50 90 70 00 90 IOR 0 10 20 30 io 50 40 70 $0 90 101 T IME HOURS TIME HOURS Summary of the containment system response for a three inch diameter cold leg LOCA.

DCCOOK 10 HOOE 2 COLO LEG LOCA BASE CASE SLOI 44 CO

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~ 41 o

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20 40 60 00 I00 L20 I 40 I6 0 20 40 60 $0 I00 I20 I40 I60 TIME HOURS TIME HOURS Summary of the containment system response for a two inch diameter cold leg LOCA.

0 DCCOOK IO RODE 2 COLD LEG LOCA. COOLDOWH AT 30 FIHR SPRAYS RUN UONYINUOUSLY ISLOI SIII

S S I I Y I"'pa ~ I '"S "I

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T IME (HOURS) TIME (HOURS)

Summary of the containment system response for a two inch diameter cold leg LOCA with containment sprays operating continuously once they are activated.

DCCOOK IO NODE I COLD LEO LOCA SPRAYS STAY ON AFTER THEY START I

SLO3 53 o vs t%

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' 10 20 )0 44 2~ ~0 0 IO 20 20 40 $0 ~4 TINR HOURS TIMe HOURS Summary of the containment system response for a one inch diameter cold leg LOCA with the accumulators assumed to be blocked and the sprays operating continuously once they have been started.

DCCOOK )0 NODE 0.) COLD LEO LOCA SPRAYS STAT ON APTER THET START

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'0 10 20 )0 CO 0 0 10 20 )0 ~ 0 )0 fo T)ME HOURS TINE HOURS Summary of the containment system response for a one-half inch diameter cold leg LOCA assuming the accumulators are blocked and with the containment sprays operating continuously once they have been started.

Sensitivity Nominal Run No. Parameter Chan ed Value Comments Sl Core power = 3315 MWt. 3250 Licensing value for Unit 1.

S2 Core power = 3588 MWt. 3250 Licensing value for Unit 2.

S3 Core power = 3425 MWt. 3250 Nominal operating power, for Unit 2.

S4 RWST temperature = 70'F. 105 Minimum tech spec value.

S5 Containment gas temperature UC = 100'F, Lowest value to maximize

= 70'F. LC = 120'F, the mass of air in DEC = 120'F containment.

S6 Thermal conductivity of 1.0 Minimize the influence of containment structural heat containment structural heat sinks decreased by a value of sinks.

1.4.

S7 Thermal conductivity of 1.0 Maximizes the influence of containment structural heat containment structural heat sinks increased by a factor of sinks.

1.4.

S8 Heat exchanger cooling rates 87'F Minimizes ice melt.

set at minimum lake water temperature = 45'F.

S9 200 gpm of upper 45 gpm Upper bound of the flow compartment spray flow that could be diverted to the drains to the inactive sum . inactive sum .

OCCOOX Io NOOE 2 COI.O LEO LOCA. SENSITIVITIES Sl. S). S I INITIAL CORE POWER 3230 MWlh (SLO$ )

INITIAL CORE POWER a 33I3 MWlh (SLO$ SI)

INITIAL CORE POWER ~ 3300 I4WIh (SLO$ 63)

INITIAL CORE POWER ~

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Summary of the containment response for sensitivity cases S1, S2 and S3.

OCCOOK IO NODE 2 COLO LEO LOCA: SENSITIVITY S~

ANSI IEIIPEIIAIUIIE RWST TELIPEAATUAE Ill F (SIUII

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Summary of the containment response for sensitivity case S4.

DCCOOK )0 NODE 1'OLO LEG LOCA. SENSITIVIT Y 51 INITIAL GAS TEMP )10 F (LC), 100 F (UC) (SLOS)

! INIIIAL OAS TEMP ~ 10 F (SI.OSS1)

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Summary of the containment response for sensitivity case SS.

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OCCOOK 10 NODE 2'OLO LEG LOCA. SENSITIVITY Sll HX COOLING WATER AT l00 F ISLOS)

HX COOLING WATER AT ~S F {SLOS Sll)

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'TIQE IHOURS) I IIIE IHOURS I Summary of the containment response for sensitivity case S8.

OCCOOK IO NOOE O'OLO LEO LOCA. SENSI'TIVITY S)2 UPPER IU ANNULUS LEAKAGE A'I ~ I GPII ISLUII

~ UPPER TO ANNULU6 LEAKAOE AT 200 OPll (SLOS SI2) o I'

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Summary of the containment response for sensitivity case S9.

0 Tjhe greatest conservatism in the analysis js that thc lce mass cx'edhted ln the calculation ls 2o43 x 10 ibm+ RealhsthcaHy~ the containment ice mass is approximately 2.7 x 10 ibm, which when melted, would add appxoximately 36,000 gallons of watex hnventory to the containhLent. At the equhlhbrhum spill QVCF crhterha~ tjhhs wouM incx'ease the active sump watex'evel by 16 inches.

1" and 2" diameter break analyses do not credit unblocking of the accumulators by the operators. This wouM add 27,500 gals. And wouM increase the active sump level by 12 inches, These analyses do not credit othex operatox acthons such as FCNhtng of the RWSY.

AIMhthonal hnventory into the contalnmcnt wouM further hncrease the active sump water level.

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