ML20147H006
| ML20147H006 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 03/25/1997 |
| From: | Diane Jackson NRC (Affiliation Not Assigned) |
| To: | NRC (Affiliation Not Assigned) |
| References | |
| NUDOCS 9703280425 | |
| Download: ML20147H006 (40) | |
Text
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- i UNITED STATES g
,j NUCLEAR REGULATORY COMMISSION
~f WASHlh0 ton, D.C. 3000H001 o
March 25,1997 gm APPLICANT; Westinghouse Electric Corporation I
FACILITY:
AP600
SUBJECT:
SU MARY OF AP600 DESIGN REVIEW MEETING REGARDING THE PASSIVE CON--
TAIMENT COOLING SYSTEM (PCS) AND WGOTHIC CONPUTER CODE On March 6, 1997, representatives of the U.S. Nuclear Regulatory Commission
.(NRC), Scientech, Inc. (NRC consultant), and Westinghouse Electric Corpora-tion (Westinghouse) met in Rockville, Maryland, to discuss (1) the recently revised WCAP-14845 (Scaling Report), (2) WCAP-14812 (Phenomena and Identifica-tion Ranking Table (PIRT) report) and (3) the WG0THIC computer code and PCS design issue closure process. Attachment 1 is a list of meeting participants.
Mr. D. Spencer of Westinghouse presented the revised Scaling Report (WCAP-14845, " Scaling Analysis for AP600 Containment Pressure During Design Basis Accidents," February 1997). The presentation included an overview of.th contents, the differences from previous reports, and the questions and discussion items addressed in the report. Mr. M. Loftus of Westinghouse presented information regarding the phenomena identification and ranking table (now in WCAP-14812, " Accident Specification and Phenomena Evaluation for AP600 Passive Containment Cooling System," December 1996).
This presentation addressed key changes to the PIRT, the expert review process, and a proposal for closure. Westinghouse is in the process of resolving the comments from expert review, which,was performed in Janu-ary 1997.. Attachment 2 is the Westinghouse hardouts. The staff noted the PIRT report did not reflect the design changes due to post 72-hour actions, such as the PCS flow rate. Westinghouse stated that the analysis was still in l
progress and that, when the design was final, the report would be updated to reflect the design. The staff and Westinghouse discussed closure paths for resolving open items and discussion questions. The staff stated that they will-work with Westinghouse to address the open issues in an expeditious manner, however, Westinghouse must propose its resolution or its approach for resolution. The staff and Westinghouse agreed on several actions (listed below).
Action items from the March 6, 1997, meeting:
1)
Westinghouse and the staff will discuss additional staff comments on WCAP-14812 in a telephone conference on March 13, 1997.
,\\
2)
Westinghouse and the staff will met in late-March to discuss Chapters 7 and 9 of WCAP-14407.
l 3)
Westinghouse will investigate how to include the expert review comments j
and Westirghouse's resolution of the comments in WCAP-14812 (PIRT).
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9703200425 970325 PDR ADOCK 05200003 goose MCRE
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. March 25,1997 4)
Westinghouse will provide additional information for the PIRT rankings in l
WCAP-14812, including references to specific scaling Pi groups, a description (where relied upon) of the engineering judgement bases, and the references (where relied upon) to specific tests and types of data that were used to determine the rankings.
5)
Westinghouse and the staff will met in April to discuss revisions to WCAP-14812.
In preparation for the meeting, Westinghoase will provide proposed revisions to address the staff's questions and comments, including Actions (3) and (4) above, and the March 4, 1997, letter, for review.
6)
Westinghouse informed the staff that they will submit a request to withdraw Chapter 13 (WG0THIC Noding Studies in Support of the AP600 Evaluation Model) of WCAP-14407 from the design application.
Included in this request, Westinghouse will provide an explanation for the request and identify any discussion items or questions that pertain to this chapter only.
If you have any questions, please contact me at (301) 415-8548.
original signed by:
l Diane T. Jackson, Project Manager Standardization Project Directorate Division of Reactor Program Management Office of Nuclear Reactor Regulation i
Docket No.52-003 i
Attachments: As stated cc w/ attachments:
See next page DISTRIBUTION w/ attachment:
~ Docket File PDST R/F TMartin PUBLIC MSlosson TQuay TKenyon WHuffman DJackson JSebrosky EThrom, 0-8 H7 4
DISTRIBUTION: w/o attachment:
SCollins/FMiraglia, 0-12 G18 RZimmerman, 0-12 G18 AThadani, 0-12 G18 JMoore, 0-15 B18 WDean, 0-17 G21 ACRS (11) l CBerlinger, 0-8 H7 JKudrick, 0-8 H7 GHolahan, 0-8 E2 l
i DOCUMENT NAME: A:SCS3 6. MIN T3 seceive a copy of teile alocuenent,inediIste in the ben: "C" a Copy without ettechment/ enclosure
- E' s Copy with attachment / enclosure
- N* = No copy 0FFICE PM:PDST:DRPM _], _ SCSB:DSSA(Qel D:PDST:DRPM l
NAME DTJackson:sg //
CBerlingerC %b TRQuay AY'O l
DATE 03//d /97 T;
03/7097
% 03/vi/97 0FFICIAL RECORD COPY
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Westinghouse Electric Corporation Docket No.52-003 cc: Mr. Nicholas J. Liparulo, Manager Mr. Frank A. Ross Nuclear Safety and Regulatory Analysis U.S. Department of Energy, NE-42 Nuclear and Advanced Technology Division Office of LWR Safety and Technology Westinghouse Electric Corporation 19901 Germantown Road P.O. Box 355 Germantown, MD 20874 Pittsburgh, PA 15230 Mr. Ronald Simard, Director Mr. B. A. McIntyre Advanced Reactor Pragram Advanced Plant Safety & Licensing Nuclear Energy Institute Westinghouse Electric Corporation 1776 Eye Street, N.W.
Energy Systems Business Unit Suite 300 Box 355 Washington, DC 20006-3706 Pittsburgh, PA 15230 Ms. Lynn Connor Ms. Cindy L. Haag hc-Search Associates Advanced Plant Safety & Licensing Post Office Box 34 Westinghouse Electric Corporation Cabin John, MD 20818 Energy Systems Business Unit Box 355 Mr. James E. Quinn, Projects Manager Pittsburgh, PA 15230 LMR and SBWR Programs GE Nuclear Energy Mr. M. D. Beaumont 175 Curtner Avenue, M/C 165 Nuclear and Advanced Technology Division San Jose, CA 95125 Westinghouse Electric Corporation One Montrose Metro Mr. Robert H. Buchholz 11921 Rockville Pike GE Nuclear Energy Suite 250 175 Curtner Avenue, MC-781 Rockville, MD 20852 San Jose, CA 95125 Mr. Sterling Franks Barton Z. Cowan, Esq.
U.S. Department of Energy Eckert Seamans Cherin & Mellott NE-50 600 Grant Street 42nd Floor 19901 Germantown Road Pittsburgh, PA 15219 Germantown, MD 20874 Mr. Ed Rodwell, Manager Mr. S. M. Modro PWR Design Certification Nuclear Systems Analysis Technologies Electric Power Research Institute Lockheed Idaho Technologies Company 3412 Hillview Avenue Post Office Box 1625 Palo Alto, 'CA 94303 Idaho Falls, ID 83415 Mr. Ben Gitnick Mr. Charles Thompson, Nuclear Engineer Scientech, Inc.
AP600 Certification 11140 Rockville Pike NE-50 Suite 500 19901 Germantown Road Rockville, MD 20850 Germantown, MD 20874
i WESTINGHOUSE /NRC MEETING PASSIVE CONTAINMENT COOLING SYSTEM MARCH 6, 1997 MEETING PARTICIPANTS M8ME ORGANIZATION CARL BERLINGER NRC/NRR/DSSA/SCSB IVAN CATTON ACRS DIANE JACKSON NRC/NRR/DRPM/PDST JACK KUDRICK NRC/NRR/DSSA/SCSB TED QUAY NRC/NRR/DRPM/PDST EDWARD THROM NRC/NRR/DS3A/SCSB i
BEN GITNICK SCIENTECH, INC./NRC CONSULTANT DAN PRELEWICZ SCIENTECH, INC./NRC CONSULTANT JIM GRESHAM WESTINGHOUSE MIKE LOFTUS WESTINGHOUSE BRIAN MCINTYRE WESTINGHOUSE BRUCE RARIG WESTINGHOUSE DAN SPENCER WESTINGHOUSE i
J0EL WOODCOCK WESTINGHOUSE DONALD CHUNG NUS/PUBLIC JACK WHEELER DOE /PUBLIC 1
4
msiiwi w m r-sui...s., m n u una im..., c. miim s.w.~2 Scaling Analysis for AP600 Containment Pressure during Design Basis Accidents WCAP-14845 A Presentation to the U.S. Nuclear Regulatory Commisssion Containment Systems Branch
~
By D. R. Spencer Westinghouse Electric Corporation Nuclear Service Division i
March 6,1994 15 C
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hisse:lNetv Al*696 -I*Itt ^1%1 Allo % ins Ni's s1A2 Mte;t IAIstRY Cen1MtNNHlN 3/6M7 Purpose of Presentation WCAP-14845 was issued to resolve NRC comments / questions on the August 1996 Scaling Analysis.
Describe Relationship of WCAP-14845 to August 1996 Scaling Analysis Discuss Resolution of Discussion items, Additional Items, Open items, RAI's and Where Addressed in WCAP-14845 e
2
I Mf3TIMilH AM APGS9 - lWMSTAito% les Ntilna CH;t I.AlttttY Cint%tt%tGN.MM7 Relationship of WCAP-14845 to August 1996 Scaling Analysis De NRC review of WCAP-14845 can be facilitated by understanding the relationship of WCAP-14845 to the August 1996 Scaling Analysis. WCAP-14845 is a significantly revised Scaling Analysis that includes new, reorganized, revised, and some largely unchanged information relative to the August Scaling Analysis.
New Material Mass and energy transfer scaling, rate of change equation validation, and LST scaling was added for completeness.
Reorcanized/ Revised /Unchanced For completeness and clarity:
Much of the material was significantly augmented, rearranged, or revised Appendix A of the August Scaling Analysis was integrated into the body of WCAP-14845 The need for Appendix B was eliminated by clearly defining all parameters and pi groups.
The labels for the LOCA time phases were changed to: Blowdown, Refill, Peak Pressure, and Long Term for consistency with the PIRT (WCAP-14811).
Status and Cross Reference Presented on the following WCAP-14845 Table of Contents 3
s
% E%TINGHot SE APMM) -- PRESENTAT10% To Nt CLEAR REGt1.AToRY Cost \\usgo% 3/&97 WCAP-14845 Table of Contents Revised =
Substantially revised from August Scaling New =
Not included in August Scaling Renomialized =
Different normalization plus revision from August Scaling (blank) =
Only minor changes from August Scaling WCAP-14845 August Sealing Status Reference EXECUTIVE
SUMMARY
New PREFACE Revised PREFACE 1.0 Introduction Revised 1.0 2.0 Dominant Phenomena Revised 2.0 3.0 Design. Boundary, and initial Condition input Data New 4.0 Constitutive Equations for Heat. Mass, and Radiation Transfer Revised 4.0 4.1 Radiation Heat Transfer 4.1 4.2 Convection Heat Transfer Revised 4.2 4.2.1 Turbulent Free Convection Heat Transfer 4.2.1 4.2.2 Laminar Free Convection Heat Transfer 4.2.2 4.2.3 Turbulent Forced Convection Heat Transfer 4.2.3 4.2.4 Turbulent Opposed Mixed Convection New 4.3 Condensation and Evaporation Mass Transfer Revised 4.3 4.3.1 Dimensionless Relationships for Data Evaluation Revised Table 9-1 4.3.2 Gas Mixture Propeny Correlations Revised 4.3 4.4 Condensation and Evaporation Energy Transfer 4.4 4.5 Liquid Film Conductance 4.5 4.6 Heat Sink Conductances 4.6 j
4.7 Constant Properties 5.1 j
I l
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% E%~fl%GHot NE AP600 PRESENTATIO% To NL' CLEAR NEGLt.ATORY CottMISNION 3W97 5.0 General Relationships for Scaling Equations App A 5.1 Assumptions App A i
5.2 Gas Mixture Relationships App A 5.2.1 Mass App A 5.2.2 Molecular Weight App A 5.2.3 Gas Constant App A 5.2.4 Enthalpy App A 5.2.5 Specific Heat App A 5.2.6 Gas Compressibility App A 5.3 Equation of State App A 5.4 Rate of Change of Internal Energy App A 6.0 Containment Gas Analysis and Equations for Scaling Revised 6.0, App A 6.1 Mass Conservation Equations Inside Containment New 6.1.1 Containment Gas Conservation of Mass Revised App A 6.l.2 Containment Liquid Conservation of Mass Revised.
App A 6.1.3 inner Film Liquid Conservation of Mass New 6.2 Energy Conservation Equation inside Containment Revised 3.1, App A 6.3 Pressure Equation inside Containment New 6.3.1 Rate of Pressure Change Equation Revised 3.1. App A 6.3.2 Normalized, Dimensionless Rate of Pressure Change Equation Renormalized 6.0 6.3.2.1 Pressure Term Renormalized 6.1 6.3.2.2 Break Source Gas Term Renormalized 6.2 6.3.2.3 Net Liquid Work Term Renormalized 6.3 6.3.2.5 Condensation / Evaporation Phase Change Terms Renormalized 6.5.6.5.1 6.3.2.6 Convection and Radiation Heat Transfer Terms Renormalized 6.5.2 i
6.4 Initial and Boundary Conditions for Containment Mass. Energy, and Pressure Revised 5.2.1 l
6.5 Momentum Equations inside Containment Revised 10.0 6.5.1 Froude Number Relationships 10.1 1
l 6.5.1.1 Forced / Buoyant Jet 10.1.1 6.5.1.2 Containment Stability 10.1.2 j
6.5.2 Froude Numbers in AP600 Revised 10.2 6.5.2.1 Loss of Coolant Accident 10.2.1 6.5.2.2 Main Steam Line Break 10.2.2 6.5.3 Froude Numbers in the Large Scale Tests 10.3 6.5.3.1 LOCA Configuration 10.3.1 6.5.3.2 - MSLB Configuration 10.3.2 5
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% r.hTINGHot %E APf40 PCEsE% TAT 10% TO NLCLEAR REGtLATORY CO%tsusslO% 3/&97 7.0 Heat Sink Analysis and Equations for Scaling Revised 3.3.3.5.2.3 7.1 Drop Analysis and Scaling Equations Revised 5.2.3.1
)
7.1.1 Drop Conductance Revised 6.6.1 i
7.1.2 Drop Mass Transfer New 7.1.3 Drop Energy Transfer Renormalized 6.6.1 7.1.4 Drop Effect on Pressure New 7.2 Break Pool Analysis and Scaling Equations Revised 5.2.3.2 7.2.1 Pool Conductance Revised 6.6.2 7.2.2 Pool Mass Transfer New 7.2.3 Pool Energy Transfer Renormalized 6.6.2 7.2.4 Pool Effect on Pressure New 7.3 1RWST Analysis 3.3.3 7.4 Liquid Film Analysis Revised 3.3.4 7.5 Internal Solid Heat Sinks Analysis and Scaling Equations Revised 3.3.5 7.5.1 Heat Sink Conductance Revised 6.6.3 7.5.2 Heat Sink Mass Transfer New 7.5.3 Heat Sink Energy Transfer Renormalized 6.6.3 j
7.5.4 Heat Sink Effect on Pressure New 7.5.5 Steel Thermal Model Revised 5.2.3.3 7.5.6 Concrete Thermal Model Revised 5.2.3.3 7.5.7 Steet Jacketed Concrete Theimal Model
~ Revised 5.2.3.3 7.6 Shell Analysis and Scaling Equations Revised 3.3.6 7.6.1 Shell Conductance Revised 6.6.4 7.6.2 Shell Mass Transfer New 1
7.6.3 Shell Energy Transfer Renormalized 6.6.4 7.6.4 Shell Effect on Pressure New 7.6.5 Shell Energy Equation Solution Revised 5.2.3.4 7.6.6 Weir and Water Coverage Timing New I
7.7 Baf0c Analysis and Scaling Equations Revised 3.3.6 7.7.1 Baffle Conductance New I
7.7.3 Baf0e Energy Transfer Renormalized 6.6.5 7.7.4 Baffle Energy Equation Solution New 7.8 Shield Building Analysis and Scaling Equations 3.3.8 7.9 Chimney Analysis and Scaling Equations Revised 3.3.9 7.9.1 Chimney Conductance Revised 6.6.6 7.9.2 Chimney Mass Transfer New 7.9.3 Chininey Energy Transfer Renonnalized 6.6.6 7.9.4 Chimney Energy Equation Solution New 1
6 1
% ENTINGilol AE APMH)
PRE.NE%TATION To NLrLEAR RE(,*1.ATORY Cott\\D$s10% JM/97 i
8.0 Evaluation of Containment and Heat Sink Pi Groups Revised 7.0 8.1 Heat Sink Surface Areas During Transients 5.2.2 8.2 Conductance Pi Gniup Values 7.1 8.3 Mass Transfer Pi Group Values New 8.4 Energy Transfer Pi Group Values Revised 7.2.1 -7.2.5 8.5 Pressure Pi Group Values Revised 7.3 9.0 PCS Air Flow Path Scaling Revised 8.0 9.1 PCS Air Flow Path Mass Transfer New 9.2 PCS Air Flow Path Energy Transfer New 9.3 PCS Air Flow Path Momentum Equation Revised 8.0 9.3.1 Dimensionless PCS Momentum Equations Revised 8.1 9.3.2 Normalized PCS Momentum Equations Revised 8.2 9.4 Values for PCS Air Flow Path Momentum Pi Groups X.3 10.0 Evaluation of Scaled Tests New 10.1 Separate Effects Tests and Constitutive Relationship Scaling Revised 9.0 10.1.1 Condensation Mass Transfer 9.1 10.1.2 Evaporation Mass Transfer 9.2 10.1.3 Convection Heat Transfer Revised 9.3 10.l.4 PCS Air Flow Path Flow Resistance Revised 9.4 10.1.5 Wind Effects 9.5 10.1.6 Wetting Stability 9.6 10.1.7 Liquid Film Model Validation New 10.2 Integral Effects Tests and AP600 Scaling New 10.2.1 Governing Scaling Equations New 10.2.1.1 Validation of Steady State Mass and Energy Transfer Equations New 10.2.1.2 Transient Validation of dP/dt Equation New 10.2.2 Steady State Validation of the LST New 11.0 Differences and Distortions between the Tests and AP600 New 12.0 Conclusions Revised I l.0 13.0 Nomenclature Revised 12.0 14.0 References Revised 13.0 7
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%) Nil %4;tH7t %E Al%90 - l'NEN6%iAllfl% let NI t'I. eau Rtt;I I A telRV Centsttwiel% N6N7 Discussion Items, Additional Items, Open Items, RAI's The transmittal of WCAP-14845 (NSD-NRC-97-5006,2/28/97) included the following items:
Responses to 49 discussion items raised by the NRC on the August Scaling Analysis are presented and incorporated into WCAP-14845.
Responses to 3 additional items raised by the NRC on the August Scaling Analysis are presented and incorporated into WCAP-14845.
Responses are provided to Open items 425 and 3202.
RAl's 480.330,480.379, and 480.380 were revised consistent with the latest PIRT (WCAP-14811) and scaling analysis (WCAP-14845).
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P ems for Olocusalen Ousing 7/25/98 Yaineen i
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'Sesang Analysis for Ape 00 e=1, T During Deelge Seele Aasidente i
Westinghouse hoe prepared Conjainment Pressure Durin Enclosure 1 m NSO4RC.96 4702, 'Seeling Analyela for Ap600 f
g Deelen Seele Aseidents'. It is stated that tNe preliminary repor supersedes WCAP 14190, '
Syste' rn" and incorporated hScaling Analyste for the Ap600 pesolve Containment Coe for discuselon on ties suelosRC staff commente on the superseded report. pollowing a trepera 1.
The superooded report.
3roups for Ap600 wiWi WCAp.14190, sentained information comparing the dimenolonisse corresponding dimensionisse groupe for the Lat The j
llmeneloniese groupe iri i
the revloed report de not relate the Ap600 to any sealed InteGrel l
1e;t este, it will be nee posary to provide a dieeusalen of the algnificance of the magnitud j
of the pi groupe and how thle teletes to sealing.
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i 2.
IVom the values given ir Appendiz 8, it la not sleer what value was used for the brook enthalpy. Messe specify the values used for hbrt,o, Dhbrk.a. mhrk o. mbrk,0,0.
Deecribe the boele for selection of eseh value. What, if any, le the difference between Dhbrk,o and Dhbrk,g.o 3.
When equation 44 of C.d A (Equetten 2 in mein body of reporti le applied to repieced by mbek,g (0 29t. Messe esplain.
.g. Estustion 82) Alee. ZetmRetm is taken se being equel to t
4.
Cn page A 1 It le stetoa reduced temperature en that air een be approelmated es en ideal ges due to high P Po < 0.06 whleh le ailow reduced pressure. The pressure conditlen given is Pr =
i
' ju(stify thle assumptlen l sout 27.3 pele (Po for air le 37.2 atm, or 547 pole). Messe a light of the containment desien pressure of 60 pels.
5.
Moose explain the feAem tempeenture Tbf.e used ing items regarding eeustion 19 on page 24. Why le the n the escond term on the Nght? The sondustances are elven eq he and her in es een etton, but se he,in and he,o in es sentenes following the equation. If he,o le the oonductance on the outside of the beffle, why era there film conductenos and conder oo'ntribudene are not kisisetlen contdbutione? Table 41 shows tha udad for me baffle.
6.
Ors page 25 in the first o mtenee of 3.3.8, de you mean downoemer and not riser?
7.
Section 3.3.8 states thei. redletion to the concrete chimney le conservatively nestected, bu; Tetde 41 shows a ru dtation contribution for me chimney. Whleh le correct?
8.
In obtaining eeustions (SUI and 131) from equatione (28) and (24), respootively, d been reptooed by L Moon emplein and state the value used for L 8.
In betions (29), (306 ewt (31) please explain how DPetm and Mm,eir are evaluat including all pressures used to obtsert the differences.
l Jut. 24
- s'E 6: 46 381 5842279 m.202
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roen se stot e r. a e. 6,n eress k
10., in section 5.2.1, the slowdown liquid mass flow rate la given as 20 000 lb Should this be 20.00)Itwn/secF m/hr.
11 In Table 61 for the kSLB the saturation temperature le given es 2349eP es b l steam density as 0.8 61 and the bulk air density as 0.732. Moose correct these u
or explain the basis for the values given.
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- 13. In section 5.2.3.1 a characteristic length of the liquid drops is celaufsted as 0 g7 feet L
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Lising a contahment v plums of 1.84 x 106 ft3 and total drop ourface staa of S x 107 42 gives a characterisi lo length of 0.0193 feet in Appendix 8, page 8 3, a i
$aracteristic length of 0.000889 feet is given, based upon a drop surface area of 2 x j
109 ft2. Whleh value quantity.
Is correct? Messe explain the physical significanos of this
- 14. diven In Seedon 3 31Mease explain how the j-conservstion of mass for the drops is handled. The equation la but doesn't i
appear again. Equation (7) shows a drop removal term and it is stated th j
equation (08).
4 the drops have a setthng reto, but this term doesn't appear in
]
Also, how is the surfac i
Appendix 8 it appsers tp area of the drops calculated. Mmm the values given in wt the total drop surfeos area is being held constant. Appendix i
E shows that during bic wdown the temperature of the drops is increasing idT/dtl at SoF
- 16. In! por sooond. Howis this possible when the dropa ente i
general, the revieweru are having diffloulty raiating the parameters Irt the ' scaling equations' to the valuaa of parameters in Appendia S. For axemple, the source drop ocating equations (67 er d GSI Ilot six pl groups, pd, peource, pe, pm, ph and pr.
Aspendia 8 Ilats four pi proups pH, pl.o, pign and pi e.
hble 7 7 lists five RPC PI groups as drop related, pradiation, peonvection, penthalpy, pgas work, and pliquid w I
ork. An additional Pl group, pmass appears in Appendia 8.
Ch page 53 it is stated thet Tau is oeuel to the inverse of Omega o, but the valva given in Appendlw 8 de i et meet this constraint.
I
- 16. On page 38 It is stated t ist C la chosen to give Po equal to 60 pela. la this true for as phases of the DECLG LO I
CAF What value is used for Dhbrk o?
- 17. Equations 54 and 58 oori thin term needed?
tain a term rf'. Since the fluid denotty is constant, why is I
- 18. There la e need for increased clartty in the nomenoisture. As dimensionless number should be defined en pegn 35. The report must to be revised to use only one term the, same quantity and to evold use of the same term for different quantitles. As examples of problems with the present draft, t
l JUL 24 *S6 6: 46 set se42279 m.ae3
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47.24.1996 07'33 the quantitles cy,d.o i
i in equetjon 87, the tiand ov,f.o appear to be the same:
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, of iktuld droplets, butmt ed.o hasn't been defined: it appears to be th two different defirdele, on page 35, ao is defined as the Irdttel gas volum g'it is not clear whethe ns are given for steam donelty on page 35; rbrk,g,o is the esme se retm o; 19.I
.The pl. group designet Mi pp in equation 71 and ppoolin equation 72 is dimen i should have mbrk.g,o in the numerstor.
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- 20. Please emplain the aigr 4
inricance of the pl groups in the host eink energy equati n
'(Esction 6.8). Values
- 5. Different factors arfor these groupe (e.g. In equatten 67) are not given os t
e used to normaAse the source drop, break pool, shell beffle thimney/shleid bul weclude any comp %
l, heet sinks, etc. goveming oguations. This would appear to erfs t
m of these pl groups thetween heat sinks.
ti. We denominator of tho left side of equation 66 has an error. The term mbrk g o hbrk,g,o should be replaced by md.o ' ov f.o
- 22. What is the normattesti for temperature differe#an used to define T'd, T'p, T'he, T'sh, etc. The normallrati cifforence are funcderuioes is defined on page 35. However, tieth temperatures in on r'ormallaed.
of time, so it is not clear how the individust temperatures ar e
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- 23. Section 9.3 refers to fo tfsis section, is titled ml.'ced convection host trenefer, while Figure 11 which is cited i ced convection heet trannsfer. Whleh le correct?
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i Follow Up hems for Discussion During 8/1/96 Telecon on i
- Scaling Analysis for AP600 Containment Pressure During DBAs*
Following are further questions and comments related to the 23 items discussed during the
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7/25/g6 telecon. Numbering corresponds to the original set of discussion items.
2.
Shouldn't the last lit.a of your response read 10.300 lbm/sec and not 20.000? The i
value 20,000 is for liquid tiow.
l 9.
Please explain how Pstm.srf is calculated. Page B 3 gives Pstm,stf equal to Ptot for drops. Please explain.
13.
The value calculated for Atot in your response appears to be incorrect. Ator.s 1.67x108 using your input values. This affects the calculated value for 4
characteristic length, by a factor of 2.
14.
It is important to establish the effect of the assumption that the drop suface area 1
l remains constant throughout the transient. The best way to show this would be to integrate the scaling equations with and without the drop contribution and plot the pressure recponse for both cases, h
15.
In your responso you mention 7 upper cas,e Pi groups.,but list six? Is there another?
i I
Addtional Discussion items i
24.
Section 7.1 makes reference to conductance si muss defined in Section 6.5.
l Should this refer to Section 8.8 and not 6.57 Have these values all been j
re-normalized relative to the shall conductance? Please give the equations used to j
calculate each of the numbers in Table 71. Can these values be directly I
compared?
i 25.
While there are indications that the set of scaling equations were integrated to determine a pressure response. e.g. top of page 48 describes integration approach for heat sinks.'no results are presented. Will a plot similar to Figure 6-1 of WCAP-14190 be included in the final version of the report? Including this plot will permit evaluation of the reasonableness of the scaling model, i
l 26.
Equation 51 gives to (is this the same as tsys?) in terms of Vo. How is Vo calculated? and where are numerical values given in Appendix B? Why is there no value of tsys calculated for the reflood oeriod (Table 7-7) ?
l 27.
Since au of the Pi groups in Table 7-7 are related to the RPC equation, for any given period the magnitude of the PI group value should be directly comparabie. If so, j
this means that the drops are contributing about 1/10 the pressure reduction of the steel heet sinks and about sa much as the concrete heat sinks during the blowdown i
period. Is this interpretation correct? Can the numerical values of Pi groups be I
directly compared between different periods?
28.
The buoyancy term (equation 102) is stated to be in terms of " thermal conter" 4
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QUG 21 '96 14:01 301 415 2*68 PQGE.31
l j
differences. It is difficult to tell from Figure 8, just how H1, H2, H3 and He are de0ned. However, the densities, rdc. rri, reh and renv are calculated based upon est temperatures. If H2 - H3 is the riser height, then using a density based upon l
est temperature will overestimate the buoyancy force by about a factor of about 2.
]
since the average density should be used. Please explain how your approach j
accounts for the variation in density along each segment of the flowpath.
29.
It would seem that moves and mcond should be consistent with the shell and chimney / shield building energy terms in the RPC equations (equations 81 and 92.
respectively). Is this what is meant by " selecting a parametric value that is known to be consutent with evaporation limits"?
30.
What is the phymcal explanation for the numerical value of the time constant t for the peak pressure being less than one-third the value of any of the other LOCA phases? Also, why is the riser Reynolds number so much larger during this phase?
31.
In section 4.2.3. would reference to the Eckert and Disguila flow regime map be appropriate to support or validate the use of forced convection for this buoyancy driven flow?
32.
In section 9.3, quantify "significantly greater scatter." Factor of two order of magnitude? Can a specific reference be made? A similar plot of forced convection data only?
t l
i auti 21 '96 14:02 301 415 2968 E. C2
Additional Diccus:Lon Items os *ssoling Analysio far AP600 contciament PrOceur3 During De:tga Basic AcBideato' 33.
In Table 9-1 the pi-groups p,,
and p are defined.
How do these pi-groups relate to the pi-group,s, defined earlier in the report?
Specifically, what is the relationship of p, and p.., to the pi-groups in the RPC and/or energy equations for the heat sinks?
4 a
34.
Equations for p and p, are given in Table 9-1 and also in equation (83).
However, the definitions do not appear to be compatible.
Please explain the relationship between these pi-groups.
Also, the term RT, appears in the definitions in Table 9-1 without the i
compressibility term, Z,
implying that air only was assumed.
Please j
explain.
i 35.
Please explain how the Sherwood number is extracted from the defiriitions i
of k,., for condensation and evaporation mass transfer given in Table 9-i 1.
That is, how is k,,, related to the data shown in Figure 97 How is i
the value of the length scale, L, introduced to obtain the Sherwood j
number?
36.
Presumably the data points shown plotted in Figure 10 are from the LST.
This should be stated explicitly (as is done in Figure 9),
i 37.
On the evaporating shell, three parallel energy transfer mechanisms are l
being modeled, evaporation, forced convection and radiation to the 4
baffle (Figure on page 23 and Section 9.3).
The following items relate to the forced convection and evaporation terms:
e What is the source of the data shown plotted in Figure 117 Is any i
of the data for a wetted surface.
How do you separate out the evaporative and convective components in the data comparison?
4 j
e Does the scaling model account for water coverage fraction? How is the amount of coverage detomined?
Is the fraction allowed to change during the event? In what manner does it change?
j 38.
Please explain what is meant by the statement in section 9.4, 'with i
approximately 1/2 the Reynolds number dependence at the same Reynolds J
number *.
39.
At the bottom of page 65, the dependence of friction on the Reynolds l
l number is stated to be -0.20 (the usual Blasius formula is -0.25) i presumably for pipe friction but not form losses. Why is the loss i
coefficient expected to be of the form C Re-" ? Is this being used i
because the form losses (1/2 of the total) are assumed to be independent of Reynolds number? Please justify the Reynolds number dependence of the otal loss coefficient.
40.
The shall coating roughness is given in microinches per inch? usually roughness is a dimensioned variable.
What quantity is being used to non-dimensionalize the roughness?
41.
In Table 9-2, what does the designation WEYr represent?
42.
Petersen gave equation (119) for a stably stratified volume. 'He states (p. 102 of your Ref. 27) that 'Because the recirculation patterns which result after breakdown of stratification are three-dimensional, for enclosures the breakdown of stratification will be modified somewhat.'
How does this fact impact the applicability to an enclosed containment?
43.
Please explain the statement on the top of page 70 which states that equation (121) is equally valid for AP600 and the LST jets with similar z.,,,,/ d. What is the relationship between z.,,,,/d and equation (121)?
August 8, 1996 2-1 Scaling 1
1
e
'3 i
44.
In Tecio 10-1 why 10 H 00 low for ths MSLB7 H:w 10 H solected in this coto? At c minimum icn't thin tha h31ght Cbova tha trOOk? D000 at mano senco to cyply thoco roletienthips fer cuch icrgs valu 0 of H/d,?
i 45.
How are the source diameters listed in Table 10-1 defined? In section i
~
10.3 Lt is stated that for the MSLB. the steam source is a 3 inch LD i
pipe.
This is not consistent with the 9.01 feet given for d, in Table 10-1.
46.
In section 10.2.1 it is stated that the jet and volumetric Trouda l
nu=bers differ by a factor of 1000 for the DECLG, yet Tigure 12 shows a j
much smaller difference.
Please explain.
i
~
i 47.
Please explain the labels in Figures 12 and 13, i.e. Unstable, Mixed, 90% Suoyant, etc.
i 48.
Please explain how the percentage of jet height that is bueyant i' '
l s
calculated.
i i
49.
On page 76 it is stated that during the DECLG LOCA the above deck atmosphere remains weakly stratified.
The earlier analysis and discussion in Section 10.3.1 suggests that the atmosphere is stably stratified in this case. 'Please explain.
i I
l i
August 8, 1996 2-2 Scaling j
l
s
% tyriscuoi SE APMHi - PRBENTAT1oN To NL Ct EAR REGtLAToRv Co%tstissio% 3/6/97 Responses to 49 Discussion items
- 1. WCAP-14845, Section 10.2 presents a scaled comparison of AP600 and the LST.
- 2. De mass flow rate, th and enthalpy difference,.ih, used to normalize the mass, energy, and g,u pressure equadons are defined in WCAP-14845 Section 6.2 and values are specified in Table 6 3 for each time phase.
- 3. Appendix A of the August Scaling Analysis was largely replaced by WCAP-14845 Section 5.
Relationships for individual gasses and for gas mixtures were developed in both. Since only gas was considered, the subscript g that is used in other sections where both gas and liquid are present, was omitted. Consequently, in WCAP-14845, m,, is the same parameter as m,,,, in Secdon 5.
p The relationship between ZR, Z,,,,R,,n, and Z,,R,,, is developed for Equation 55 in Seedon 5 of WCAP-14845.
- 4. The basis for the low air reduced pressure that justifies treating air as an ideal gas is provided in WCAP-14845 Section 5.1. Since the maximum partial pressure of air is 19.7 psia, the reduced pressure is Pr = 19.7/547 = 0.036. Consequently, the deviadon from ideal gas behavior for air is acceptably small.
- 5. The baffle temperature and conductance discrepancies were corrected and the revisions presented in WCAP-14845 Section 7.7.
- 6. The inadvenent reference to the riser should have been to the "downeomer". The corrected text is presented in WCAP-14845 Section 7.8.
- 7. Radiation was not included in the chimney calculation as noted in WCAP-14845 Section 7.9.
- 8. The parameter L has been replaced in WCAP-14845, Equadon 13 by the channel hydraulic diameter, d and in Equation 14 by the drop diameter, d.
n
- 9. AP,,, is defined in WCAP 14845 following Equation 8, and Pm,, is defined following Equadon 9 De bulk steam and air partial pressures used in these parameters are presented in Table 6-3. De surface values of air and steam partial pressure differ for each heat sink, depending upon the time phase, and are not presented. Rey are, however, defined by the saturation pressure of each heat sink surface, the temperature of which is tracked as explained in Section 7.
- 10. WCAP-14845 shows the (average) LOCA blowdown liquid mass flow rate is 7,777 lbm/sec. The break liquid flow rate was determined from Figure 3-2, and is the sum of the drop and pool flow rates presented in Table 6-3.
I1. The MSLB saturation temperature, bulk steam density, and bulk air density were revised and are shown correctly in: WCAP-14845, Table 6-3.
- 12. The evaporating, subcooled, and dry shell areas are presented in WCAP-14845, Table 8-1 and all add to 52,662 for each time phase.
- 13. The drop characteristic length was calculated in Section 7.1 to be 0.0242 ft, or 0.29 in. De 16
=
e
% FATi%t; Hot %E APMW - PREsE% TAT 10% 10 Nt CLEAR REGt1.AToRv CO%tsassio% 3/U97 characteristic length is the ratio of containment volume to drop surface area. De characteristic length is a measure of the coupling distance between the liquid surface and the surrounding gas. It can also be visualized more simply in this case as a smooth liquid surface with an overlying gas layer 0.29 inches thick. The very small length value indicates strongly coupled components (gas and dropst
- 14. The drop conservation of mass Equation 97 of WCAP-14845, includes terms for the source rate, the flashing rate, and the evaporation rate. The source is assumed to occur only during blowdown at the rate given in Table 6-2. De flashing and evaporation rates are calculated and discussed in Section 7.1. A drop removal term is not included in the equation since it was desired to maximize the effect of the drops on containment pressure.
The discussion and calculations in Section 7.1, and the pi group values in Section 8 for the drops shows that even with no fall-out, the drop effect on containment pressure is small. Since the drop surface area will reduce over time due to evaporation, fall-out, and agglomeration, even the "small" effect is overestimated.
- 15. Each ['i group and time constant is clearly defined in WCAP-14845 and given a unique name by the use of subscripts. That name is used consistently when evaluating and referring to the pi group.
De errors in the August Scaling Analysis were corrected and inconsistencies were climinated in WCAP-14845.
- 16. The complicated reference value for pressure was eliminated in WCAP-14845. Pressure is simply referenced to the initial value during each time phase. De definition of the dimensionless total and steam panial pressures are presented in Section 6.3.2 and the reference values are presented in Table 6-3.
- 17. Since liquid density, p, is effectively constant, p,* is always 1.0 and was eliminated from the equations in WCAP-14845.
- 18. The scaling analysis presented in WCAP-14845 has been clarified and inconsistencies removed.
Nomenclature was clarified as much as possible, although the extensive number of parameters works against simplification.
- 19. The comment is correct. The dimensional pi-pool group was not useful and was eliminated.
- 20. The terms representing energy transfer between the heat sinks and containment gas were redefined and consistently normalized in WCAP 14845.
- 21. The comment is correct. De redefined drop pi groups are presented in WCAP-14845, Section 7.1.
- 22. Each temperature difference is normalized to the temperature difference between the bulk lluid and the surface at the initial conditions of each time phase.
- 23. WCAP-14845, Section 10.1.3 con:ains a revised discussion of forced convection heat transfer.
The ambiguous reference to mixed convection data was eliminated.
- 24. The incorrect section reference was corrected in WCAP-14845. De conductances are normalized to the shell plus coating conductance. De conductance pi groups are clearly defined for cach heat 17
M ENTIM; Hot sE AP600 - PRENENTATIos To NL C1. EAR REGLLATORv Costsussio% 3MN7 sink in Section 7 under a ".. Conductance" subheading. Since the normalizing value is always shell conductance, the conductance pi values can be compared horizontally as well as vertically in Table X-2.
- 25. It is necessary to integrate the heat input to heat sinks over time to predict surface temperatures that are used to evaluate the heat transfer rates, and hence the pi values, for each time phase. This int gration process is described under the subheading "... Dermal Model" in WCAP 14845. The reasonableness of the scaling equations is verified by comparing predictions of the steady state and transient equations to LST measurements in Section 10.2.
- 26. The single time constant used in the containment mass, energy, and pressure scaling is defined in WCAP-14845, Equation 59.
V,, = 1.741xiff ft' is the total gas volume inside containment, both above and below deck. During refill the break source now stops, so the time constant, with flow rate in the denominator is undefined. However, Table 8-3 presents a time constant calculated using a reference break steam flow rate of 200 lbm/sec.
- 27. The reviewer's interpretation of the pi groups is correct. WCAP 14845. Table 8-5 shows the drops affect pressure the same as the steel heat sinks during blowdown and less than 1/10 as much after blowdown. Pi groups are normalized to different steam mass flow rates in each time phase, so cannot be compared between different time phases.
- 28. Figure 91 of WCAP-14845 clarifies the location of thermal centers. De discussion in Section 9.3.1 and Figure 9-2 show how the thermal centers are used with the density to calculate the buoyancy. De example calculation in WCAP-14845 is repeated below.
Figure I shows an example of a simplified PCS buoyancy calculation using density values calculated for the beginning of the long term time phase of the LOCA. De density variations over each leg of the air flow path are assumed to be linear. De net buoyancy is represented by the enclosed area. The buoyancy calculated using the thermal center approach is shown for comparison. For this case both the distributed density and thermal center approaches give the same result. Note that for this assumed case, the net buoyancy is not affected by the amount of heat transferred from the riser to the downcomer, (Moving point 2 along the horizontal axis does not change the area within triangle 12 3 1.
However, moving point 2 does change the relative ratio of negative dowrcomer buoyancy to pmitive riser buoyancy. Moving the thermal centers of the downeomer and riser up to the 84 ft
, elevation, as was done for the AP600 scaling calculation, significantly reduces the net buoyancy.
- 29. The text in WCAP 14845, Section 9.3.1 was revised to be consistent with what was done:
condensation on the chimney was pan of a simultaneous solution for the PCS air flow path air and steam mass, energy, and momentum (including buoyancy).
- 30. De PCS air flow path time constant is the ratio of the air now path volume to the volumetric Dow rate. At the time when the peak pressure occurs, the shell temperature and evaporation rate are higher than at any other time, so the buoyancy induced volumetric air flow rate is highest.
Consequently, the time constant is at its lowest value during the transient, and since the riser Reynolds
. number is proportional to the riser volumetric flow rate, the riser Reynolds number is at a maximum.
The PCS air flow path time constants are presented in WCAP-14845, Section 9.l.
- 31. An Ecken and Metais flow regime map showing the boundaries between free, mixed, and forced convection flow is presented in WCAP 14845, Figure 4-1. De location of the downcomer, riser, and 18 l
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% EN18%Gilot hE AP600 - PREhE%TATION To Nt rt. EAR RFEllATORY Cost \\Ussio% NW97 s
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~~ - r -- -~ ~ t. =~ 4. - -- ~ ; --
r -- -
160- --
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~ ~ - -
j Chithney Th6rmal l
[
~ ~ ~ ~ 4 h -~~ ~ i- ~~ +-- ~ ~. contes.1 -.-. -. {...~.--. -- ~ ~ ;.-..~. 3 140-9 j
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- 2. 120 i- ~ ~- - ~~~-'-~~---~---~~r-~~~-
~~-~~~
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, - 3 [. Riser.T4p....................+.....Downcomer. niet......h....
100 i
.9 e
s w
80----- * - -
- ~~~~ ~
~~~ Oowncon1st-~ ~ ~~~ ~
t-- -
l Therm Crjtr l
6&' ' * - - I * - -
i * * --
' -- -
- t
- i
- - i -- *- i- -- *- i ----- -
4_... 4.____+_
..p.....p.....p_...q....a
..........1..........J.......l..
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.......J........:
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' Riser Therma Centhr j
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- - - * ----- 4 4 -
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- - - +! --- Thermal Center C61culatiort
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Bott@
t!inear Valriation Calculatior) s.06 0.d61 0.d62 0.d63 0.d64 0.065 0.d66 0.d67 0.068 0.d69 0.07 Air Density (Ibm /ft^3)
I Figure i Buoyancy Calculation for the AP600 PCS Air Flow Path Compar ng Distributed and Thermal Center Approaches chimney operating points from the scaling analysis are shown on the map to help establish that the riser flow is forced convection.
- 32. A revised discussion of free and forced convection heat transfer and uncertainties are presented in WCAP-14845, Section 10.1.3. The forced convection data are no longer justified by comparison to mixed convection test date.
1
- 33. The mass transfer pi groups are defined in WCAP-14845, Section 7 for each heat sink: for example, Equation 122 for condensation and Equation 123 for evaporation. The relationships for j
condensation and evaporation mass transfer comparisons to test data are in terms of Sherwood number, defined in Section 4.3.1. Sherwood number comparisons to test data are presented in Section 10.1.1 and 10.1.2, The inconsistent definitions for the pi groups in the August Scaling Analysis was j
eliminated in WCAP 14845.
- 34. De definitions are clarified as noted in the response to discussion item (33).
The compressibility range in AP600 is 0.97 < Z,,, < l.0, where the minimum value corresponds to 40 psia of saturated steam. The assumption that Z,,, = 1.0 introduces an error of less than 37r in the equation of state, and permits steam to be modeled as an ideal gas. This is a significant simplification over the necessary steam table look-up required to quantify Z,,,, for only a small error in the equation 19 i
~.
%Es11%f;Hol %E AP600 - PRENENTATION To Nt ct EAR REC 1.ATORv Co%t\\tisNION 3/M97 of state. Although compressibility is neglected in this application of the equation of state.
compressibility has been considered where it is more signincant: the evaluation of the enthalpy rate of change with pressure in the development of the rate of pressure change equation presented in WCAP-i 14N45, Sections 5 and 6.
l
- 35. Section 4.3.1 of WCAP-14845 presents the derivation of the Sherwood number relationships foi free and forced convection that are compared to test data in Figures 10-1 and 10-2. The development
- follows, i
The expression for the mass transfer coef0cient for free connetion condensation mass transfer:
0.13 D<,,
P,,
' _a p '"3Sw, in k" =
iiT,(v /g)'" P,,,,,
p, can be rearranged in the dimension less form:
2 k R T (v /g)'" P,,,,,
'g" in g
o D,, P,,
p, j
The term (v /g)'" represents length, so the right side of the equation is the Sherwood number plotted in Figure 10-1. Note that multiplying both sides of the equation by L, and dividing both sides by the term (v /g)'" produces the more familiar form:
r ita k,.. R T,'L P'**'" = 0.13 3
L a
._ P Se,'"
or Sh = 0.13 Grt"' S e "
t D,,P, (v /g)'" p, The evaporation mass transfer relationships are developed similarly.
- 36. The evaporation test data points in Figure 10-2 are from the STC Flat Plate Test. The Hgure title was revised in WCAP-14845.
- 37. Figure i1 of the August Scaling Analysis was mixed convection, not free convection or forced convection. The mixed convection correlation Ogure was replaced with discussions cf he free t
convection and the forced convection correlations in WCAP-14845, Secuon 10.1.3.
l The scaling *nodel accounts for the water coverage fraction. The area of the evaporating, subcooled, and dry shell regions change during the transient The determination of area is defined by Equation 135 and the discussion in Section 7.6.6. The resulting areas for the three shell regions are presented in Table 8-1 for each time phase. A maximum evaporation rate of 40 lbm/sec, consistent with WCAP.
14407, Section 7, is used.
- 38. What is meant is the slope, or exponent on the Reynolds number, is 1/2 that for friction at the risci Reynolds number corresponding to the peak containment pressure. This was clarined in Section 10.l.4, third paragraph of WCAP-14845.
- 39. The Blassius friction factor correlation is a reasonable approximation for low turbulent Reynolds 20
i l*
WErrtwuol%E AP600 - PRESENTATIo% To NL Ct. EAR REr.LLATCCv ComDsslos 3/6/97 i
l-numbers. However, at the riser Reynolds number corresponding to the peak containment pressure (Re l
= 163.000), the tangent to the r/d = 0.0001 curve on the Moody friction factor chart has a slope of -
0.20, hence the value used in the calculations.
i Since form losses are known to be independent of Reynolds number at high Reynolds numbers (K -
l C Re"), and since the frictional losses are known to have only a weak dependence on Reynolds i
l number at high Reynolds numbers (flJd = C:Re", where n = -0.20), it is rtasonable to expect the sum l
of the form and friction losses can also be approximated by a function of the form K,, = C Re'", An i
3 approximming function can be defined as the tangent to the approximated function at some Reynolds number, R.,. The values of C, and m in the approximating function can be determined as follows with the assumption l
l l
- 1. The form. K, and friction losses, Illd, are equal in magnitude at Re = R. so C = C:Re",
j i
i j
and with the definition of the tangent:
l 1
l
- 2. The magnitudes of the approximated function, (K+flJd), and the approximating function.
l K,, are equal at Re = R.,, so K,, = K + flld, and 1
- 3. The slope of the approximating function dK,.,,/dRe is equal to the slope of the approximated function d(K+flJd)/dRe, at Re = R...
l From assumption (1) : C: = C,/R,,"; from assramption (1) and definition (2): C = 2C/Rj"; and from 3
definition (3) : nC:R,," = mC Rd*8 Substituting the first and second expressions into the third to 3
climinate C: and C results in the equation m = n/2. Since n = -0.20 at Re = 163,000, m = -0.10 3
This discussion was included in Section 10.1.4 of WCAP-14845.
- 40. The roughness should have been stated as micro inches, not micro inches per inch, and was corrected in Section 10.1.4 of WCAP-14845.
i 41, WDT, an acronym for Water Distribution Test, is spelled out in Table 10-7 of WCAP 14845.
- 42. The stability criteria shows the containment atmosphere is stably stratified during most of the l
transient (after approximately 5 see during a DECLG and 80 see for the MSLB). It is considered l
unlikely that a more rigorously applicable stability criteria would permit the conclusion that the atmosphere is unstable during the majority of the transient time. Therefore it is necessary to address the consequences of stratified gas volumes in the AP60(revaluation model. The consequences of stratification are addressed in WCAP-14407. Saction 9.
f 43.' Equa. on 121 of the August Scaling Analysis is Equation 89 of WCAP 14845. The sentence was rephrased in WCAP-14845 to state " Equation (89)is equally valid for AP600 and the LST with jets that are forced over most of the containment height."
Equation 89 was derived from Peterson's equations for entrainment into a forced jet, so for Equation 89 to be applicable, it is necessary that the jet be predominantly forced, or Z
= H. Peterson also j
m examined a stability criterion for buoyant jets, and concluded that buoyant jets almost never break up stably stratified liuid volumes. Thus, the criteria for instability are a predominantly forced jet, and
)
violation of Equation 89. This paragraph was added to Section 6.5.2 of WCAP-14845.
j I
21 i
i WE%TINCIInt %E APMHD - ITENENrATION To NLCLEA3 REGtLAToHY CostSnhSlo% 3/&97 l
\\
l
- 44. The MSLB values in Table 10-1 of the August Scaling Analysts are juxtaposed. They were corrected in WCAP-14845, Table 6-4 to read, first line: 74.8, 9.01, 1/8.3, and the second line: 2.46.
l 0.256, 1/9.61.
l Figure 3 of Peterson, I. J. of H & M. T. Vol 37, shows stability data for 2 < H/d < 40, which includes the range for both the LOCA and MSLB in both AP600 and the LST. Thus, we believe the relationships are valid for our values of H/d.
- 45. The values in Table 10-1 of the August Scaling Analysis are incorrectly listed and are corrected as noted in the response to Question 44.
- 46. Figure 12 of the August Scaling Analysis is Figure 6-2 of WCAP 14845. Beth figures show the ratio of jet Froude number to volumetric Froude number is consistently 1000. Note the left and right scales on the figure.
- 47. Figures 12 and 13 are Figures 6-2 and 6-3 of WCAP-14845. The following paragraphs of clarification were added to WCAP-14845.
Stable / unstable regions are distinguished by the.iP600 values of Fr, presented in Table 6-4. calculated l
from Equation 89. Figures 6-2 and 6-3 show the AP600 transients are expected to operate predominantly in the stably stratified regime.
For entrainment calculations it is important to know whether the jet is buoyant or forced, since buoyant and forced jets entrain the surrounding fluid at different rates. A forced jet transitions to a buoyant plume after traveling some distance and dissipating some of its kinetic energy. Thus, the first criterion to examine is whether the jet remains forced over the full height of containment, that is, what is the jet Froude number for Z,, = H? The values were calculated for AP600 with Equation 86 and presented in Table 6-4. Comparison to the transient Froude numbers in Figures 6-2 and 6-3 show this criteria is never satisfied. So the jet always transitions to a plume before reaching the top of containment.
j The second criterion to consider is, since the jets cannot always be modeled as forced, can the jets be modeled as always buoyant? The strict answer is no, since Equation 86 always gives a finite value of Z,..
However, if the jet is predominantly buoyant, say over 9% of the containment height, then it is reasonable to model the jet as buoyant over its full height. The value for Z,. then is 10% of the height, and the corresponding jet Froude numbers are presented in Table 6-4. When compared to the AP600 jet Froude numbers, Figure 6-2 shows the DECLG jet height is 90% buoyant for the entire post blowdown time. Figure 6-3 shows the MSLB jet height does not become 90% buoyant until the end of the transient. Prior to the end of the MSLB the jet transition height must be calculated as a function of the jet Froude number and modeled as mixed (that is, part forced and the remainder buoyant) to a;eurately calculate entrainment..
- 48. The part of the jet height that is buoyant is H - Z,,, where H is the containment height above the l
source, and Z, is the height of the forced jet calculated from Equation 86 of WCAP-14845.
t i
- 49. The phrase " weakly stratified" is used as a qualitative measure of the vertical density gradient obs1rved in the LST data for the LOCA configurations. Strongly stratified would be nearly pure air at the feck elevation and nearly pure steam at the dome, which was never observed in the LST. If the jet entrainment is high enough, the resulting fluid circulation can nearly eliminate vertical l
l 22 l
1
l l
M E%TINGilot AF. Al%00 - PRE.%ENTATIo% To NLU. EAR Hrctt4 Ton Costsassio% 3/uv7 I
concentration gradients, resulting in a weakly stratified atmosphere.
" Stably stratified" is not related to whether the gradient is weak or strong, only that it is stable.
1 i
l I
l i
1 t
l l
r l
I l
l l
i i
l j
l 23 4
l l
Items Needed to C mplet3 Scaling Report item 1 The information developed needs to be used to identify the important phenomena in a quantitative way. Calculated values for the rate of pressure change soustion pi groups should be listed for each phase of the accident and the importance of the phenomena they represent categorized based upon the magrutude of the pi group values. For all of the hign or medium importance phervsmena, the repon should address how the phenomena is bounded for the range of pivameters applicable to AP600. This could be done by reference to more detailed reports. A table similar to 21 but with the *how" instead of the "effect."
Results of integrating the scaling equations for the AP800 should be presented in the form of a plot of calculated pressure versus time. This is an essential zero-th order check which shows that the modelis giving reasonable results. Both LOCA and MSLB should be presented. This should help validata the " magnitude" and " timing" of the AP600 pressure response.
item 2 l
The scaling methodology should be applied to the LST to show that the approach correctly' l
identifies important phenomena and yields a reasonable prediction of the steady state pressure when compared to measured data. Representative tests should be selected to l
l l
demonstrate each of the important phenomena for both LOCA and MSLS conditions.
!?m m 3 Rate of pressure change equation pi group values should be calculated and presented for the LST. This would show the non prototypicality of the LST as a scaled test for AP600 l
but it would also show areas where test data are applicable.
l 24
4 M ENTI%cHot %E APM60 - Pl.EsE% RATION To NL CLEAR REctLATORY Co%t%tissio% N6/97 Responses to 3 Additional iterns l
ITEM 1. Calculated values for the rate of pressure change equation pi groups are presented in Table 8-5 for each phase of the LOCA and for the MSLB. The magnitude of the pi group, relative to 1.0 represents the importance of the phenomena. The phenomena represented by the pi groups are identified by the subscripts on the pi groups and the definitions of the pi groups. How the high and i
medium ranked phenomena are bounded is presented in WCAP-14407, Section 2.
The mass, energy, and pressure rate of change equations were validated by comparison to LST data as described in Section 10.2. The comparisons show the rate of change calculations agree with the test measurernents.
ITEM 2. The scaling methodology was applied to the LST in Section 10.2. De predictions and i
measurements presented in Table 10-10 showed good agreement for the dominant phenomena (condensation and evaporation) The steady-state scaling model predicts the total steady state LST energy transfer for 21 tests with an average deviation between predictions and measurements of less than 19 and a standard deviation of 139. The scaling analysis shows the dominant phenomena inside containment during a MSLB are also dominant during a LOCA. Therefore test results are valid for both transients.
ITEM 3. Transient rate of pressure change equation prediction are presented and compared for the LST and scaling equations. Pi group values were also calculated and compared to LST measurements to validate the mass and energy rate of change equations at steady state. Since the pressure rate of change equation is a combination of the mass and energy equations with the equation of state.
validation of the mass and energy sluations also validates the pressure equation.
l The scaled comparisons show the dominant phenomena in the LST represent those in APo00, and the lest data validate the sealing equations.
i I
l 25
]
e M ENT1% Hot sE APeon - PREsE% TAT 1o% To NLCt. LEAR NEG11AToRY Co%t%DSSlo% 3N97 4
Open items 425 and 3202 OITS 425. ACRS Meeting on PCS Testing (3/16/94) The Subcommittee recommended that W evaluate the potential for stalling / restart of the air flow around containment, for the case of high ambient temperature conditions.
Resp nse:
The shield building walls are 3 ft thick concrete. 'lhis thickness strongly damps the effect on the inside of the shield building of solar radiation, that cycles from day to night. Calculations (Schlichting, Bormdary Layer Theorv,6th Edition, pp 85-86) show the wave length of a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> thermal cycle propagating through concrete is 3.05 ft. Thus the peak temperature on the inside of the structure occurs in-phase with the peak in the outside surface temperature. However, the damping reduces the amplitude on the inside to less than 0.2% of the outside amplitude.
A much more immediate effect on the inside of the shield building is due to the ambient air that is -
drawn into the downcomer by the natural circulation induced by the warmer containment shell, and by the wind-positive PCS air flow path. The wind-positive behavior is such that the external wind induces a positive (down the downcomer and up the riser) air flow. Thus, the ambient air will always ne in thermal communication with the inside of the shield. Consequently, the dow:ncomer side of the shield will respond directly to the outside air, but not to the solar hes: load.
OITS 3202. 21.6.514 Westinghouse needs to justify the use of correlations ou de their range and discuss the impact of these correlations on AP600 licensing calculations Respmse:
The rang; of correlations for the dominant phenomena, condensation, evaporation, and heat transfer are all used within the range of the data as shown in WCAP-14845, Sections 10.1.1,10.1.2, and 10.1.3. All correlations used to represent significant AP600 phenomena have been validated over a range appropriate for AP600 operation.
l 26
I NRC REQUEST FOR ADDITIONAL INFORMATION Question 480.330 Revision i Re: (WGOTHIC MODELS AND PHENOMENA)DOWNCOMER Does WEC consider that the effects of the downcomer are negligible. and if so how has this been demonstrated?
How can the effects of a downcomer be quantified without experimental validation?
Response
The effects of the downcomer on AP600 are quantified by the PIRT (Reference 480.330-1) and scaling analysis (Reference 480.330-2), and shown to be of low to moderate importance. The effect of the downcomer on AP600 is small, but is not negligible. The downcomer is modeled in the evaluation model.
The lack of a downcomer in the LST has no effect on the data that were used to validate phenomenological models or on the use of the LST pressure as a comparison to the evaluation model. This is true because the LST is not used as a transient representation of AP600. He data collected from the LST at numerous locations for heat and mass transfer to the riser provide measurements of heat flux, shell surface temperature, air temperature, and air steam partial pressure that are used to validate the heat and mass transfer correlations. His separate effects approach is not affected by the presence or absence of a downcomer.
The do.vncomer in the AP600 evaluation model is modeled as a channel operating with mixed convection thermal interactions with the shield building and baffle. The scaling analysis energy pi group for heat transfer from the baffle to the downcomer, no, in Table 8 showed the energy transfer to the downcomer to be minor. The buoyancy contribution of the downcomer to the net PCS air flow path buoyancy is shown by the value of x... in Table 9-1 to be minor. The phenomena that occur in the downcomer were addressed in the PIRT and were all ranked low to moderate importance. Because the PIRT and scaling analysis showed the downcomer and its associated phenomena to be minor, it is sufficient to model the downcomer using ordinary analytical models.
References:
i 480.330-1 M. Lofrus, J. Woodcock, D. Spencer, " Accident Specification and Phenomena Evaluation for AP600 Passive Containment Cooling System". WCAP 14811. December 1996, Westinghouse Electric Coproration.
480.330-2 D. R. Spencer, " Scaling Analysis for AP600 Containment Pressure During Design Basis Accidents,"
WCAP-14845, February 1997, Westinghouse Electric Corporation SSAR Revision: NONE 480.330 W M r $ 00se gey, t 27
I NRC REOUEST FOR ADDITIONAL INFORMATION h
i Question 480 379 Revision 1 Re: (The following questions are based on the WEC March 29 30.1995 ACRS Presentation on Scaling).
Where does the "U" in the correlations come from when the main steam line break (MSLB)is being analyzed? How were equations derived, what assumption were used?
Response
The containment t.te of pressure change equation is derived from the energy equation for the containment gas. The energy equation for the containment gu is derived from the energy equation for a control volume which relates the internal energy, u, to the enthalpy fluxes and heat fluxes through the control surface. The derivation of the energy j
and rate of pressure change equations for the scaling analysis are presented in Section 6 of the scaling report (480.379-I).
References:
480.379 1 D. R. Spencer, " Scaling Analysis for AP600 Containment Pressure During Design Basis Accidents,"
WCAP 14845, February,1997. Westinghouse Electric Corporation.
SSAR Revision: NONE i
l l
480.379 W @ use
.Rev.1
i NRC REQUEST FOR ADDIT!ONAL INFORMATION Question 480.380 Revision i Re: The following questions are based on the WEC March 29-30.1995 ACRS Presentation on Scaling.
The Large-Scale Test air annulus was scaled by matching Reynolds (Re) numbers. This tends to result in higher j
heat transfer and more vigorous in-containment convection than might be expected in the AP600. It would seem that scaling to the following form would be more appropriate:
integral (q dA / v)
What are the ramifications?
Response
De scaling analysis (Reference 480.380-1. Sections 10.1.2 and 10.1.3) demonstrated that the Reynolds number is the appropriate dimensionless group to use to scale evaporation mass transfer and heat transfer to the riser.
References:
480.380-1 D. R. Spencer. " Scaling Analysis for AP600 Containment Pressure During Design Basis Accidents."
WCAP 14845. February.1997. Westinghouse Electric Corporation i
SSAR Revision: NONE 1
4 W Westinghouse Rev.1
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AP600 PCS PIRT' March 6,1997 M.J.Loftus 412-374-5957 8
- _-. - _=
PIRT Chronology o
Some Key Changes /Impovements o
Expert Review Process o
Process to reach PIRT Closure I
i a
\\
PIRT Chronology i
)
o Pre-1996
)
Initial PIRT identified key containment phenomena l
for evaluation in separate effect tests and scaled l
testing (late 80's)
Interim PIRT's developed and published (e.g., joint scaling and PIRT report in 1994) i j
o 1996 4
Preliminary (February) version of PIRT published j
consistent with available scaling analysis results i
EPRI A&TRT reviewed PIRT Revsied PIRT format provided in May at ACRS meeting Efforts to address NRC comments on containment test analyses, model development, and documentation throughout the year Scaling analyses revised in 1996 (issued February, 1997) and factored into December PIRT 1
I o
Final Product - December,1996 PIRT with bases for ranking
I Some Key Changes / Improvements Between February PIRT and December PIRT e
l o
Some report format changes,for example Added chapter (2.0) on process Added specific test objectives and overall test l
conclusions Added paragraph for each phenomena on ranking Added appendix summarizing sources for ranking bases (scaling, tests, sensivitivities, engineering judgement, first principles) o PIRT structure improved,for example Included phenomena for both volumes and structures Phenomena listed inside to outside l
o New phenomena added,for example Break source mass and energy release Intercompartmental flow in containment volume Gas compliance in containment volume Hydrogen release in containment volume Heat capacity of heat sinks Initial conditions of containment 4
Some Key Changes / Improvements l
Between February PIRT and December PIRT (continued)
(
l Some rankings changed from Low to High for Long o
l Term,for example Heat sink liquid film energy transport Heat sink horizontal film conduction Heat sink internal conduction i
Fog in the containment volume i
For those phenomena that are related to or strongly i
affected by the condensation rate which was ranked High o
Some rankings changed from Medium to Low for Blowdown,for example Heat sink liquid film energy transport Convection from containment to heat sinks Radiation from containment to heat sinks Based on available scaling analysis results and test results Note: not a complete list of changes
Expert Review Process o
Supplements prior expert reviews and confirms that previous comments addressed o
Performed in parallel with NRC review of WCAP-14811 in January,1997 o'
External Experts Per Peterson, UCLA Tom Fernadez, EPRI Sol Levy, Levy & Associates (EPRI)
Doug Chapin, MPR Assocaites (EPRI) o Internal experts Larry Hochreiter, Consulting Engineer Gene Piplica, AP600 Test Manager Larry Conway, PCS Patent Holder Terry Schulz, AP600 Systems Design Engineer o
Comments received on phenomena identification o
Comments received on phenomena ranking
l PIRT Closure s
o Te Waddressed once NRC sp(cific ' comments / discussion items ere availab!c t
o Resolve Expert Review Comments Weltinghouse and NRC td agree on s'pecific changes to o
WCAP o
Proposed format is a working level PIRT closure meeting 1
o Suggested Ground Rules only those items neccesary to make report correct are to be changed minimize changes to WCAP i
add supporting appendices as necessary l
l l
t
\\
i Summary o
PIRT has changed / improved since February,1996 o
Westinghouse has received specific Expert Review comments on December,1996 PIRT o
Westinghouse has proposed " path to closure" Obtain NRC specific comments / questions W to provide responses on comments / questions W/NRC working-level meeting on proposed responses
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