NRC-96-4624, Provides Tables Identifying Key Elements of AP600 Wgothic PCS Design Basis Analysis Approach
| ML20096G838 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 01/23/1996 |
| From: | Mcintyre B WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| To: | Quay T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NTD-NRC-96-4624, NUDOCS 9601260115 | |
| Download: ML20096G838 (18) | |
Text
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Westinghouse Energy Systems Box 355 Pmsburgh Pennsylvania 15230 0355 Electric Corporation NTD-NRC-964624 i
l DCP/NRC0449 Docket No.: STN-52-003.
January 23,1996 l
Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555 ATTENTION:
MR. T. R. QUAY
SUBJECT:
KEY ELEMENTS OF TiiE AP600 WGOTHIC PCS DBA APPROACH i
Dear Mr. Quay:
The attachment provides tables identifying key elements of the AP600 WGOTHIC PCS Design Basis j
Analysis (DBA) approach. Table 1 provides an item-by-item response based on an outline of issues provided by the NRC at the June 29,1995 Senior Management Meeting. Table 2 summarizes the WGOT111C input pa ameter groupings and how each is bounded.
The original versions of these tables were provided to the NRC at the July 27,1995 meeting with NRC staff. Changes were made to the tables to reficct changes in the PCS DBA approa.h as discussed at this meeting.
Please contact John C. Butler (412-374-5268) if you have any questions concerning this submittal.
l HAY /pfM Bri6n A. McIntyre, Manager Advanced Plant Safety and Licensing
/nja Attaci. ment T. Kenyon, NRC (w/o Attachment) cc:
D. Jackson, NRC (I A)
E. Throm, NRC (1 A)
J. Kudrick, NRC (I A)
P. Boehnert, ACRS (I A)
B. A. McIntyre, Westinghouse (w/o Attachment)
N. J. Liparulo, Westinghouse (w!o Attachment) 260Cfi
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Tcble 1 Kcy Elamenta cf the AP600 WGOTHIC PCS DDA approach SSAR AP600 PCS DBA approach Reports and sections addressing the tope Topic
SSAR 6.2.1.1 - 6.2.1.3
3 all important phenomena and conservatively accounts for AP SSAR 6.2.1.2.1 subcomparte uncertainties including those due to correlations and models.
computer code, and scale, to examine the following cnteria:
T(t),
SSAR 3.11 (To be
-P s 45 psig revised) g
-P s 50% (45 psig) 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />
- APg,,,,,, s intemal wall structural capabihty NTD-NRC-94-4166
- AP,% s structural capabihty
- AP600 PCS Design Basis Analysis (DBAl
- T(t) s T(tl,%,mo, and Margin Assessment." pp. 3-10.
NTD-NRC-95-4459 "Strat.fication and Mixing Effects on AP600 Passive Containment Cooling System DBA,'
52.0 and 14.2 through 4.5 e Definition and selection of design hmits for pressure and ED The basea for design limits have been provided. Margin between P
,P SSAR 3.8.2, 6.2.1.1.2 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> design limits and failure limits is consistent with current A
SSAR 3.8.3.3, 6.2.1.2.1 subcampartment cperating plants. The containment shell material provides AP,g SSAR 6.2.1.1.4 margin batween design and failure pressure similar to that for T(tl SSAR 3.11 y
current plants (see section 3. of July 27,1995 presentation.
Margin from design SSAR 3.8.2.4.1.2, hmits to failure limits 3.8.2.4.2 Rewseon 1 November 17,1995 Page 1 of 17
I-Topic SSAR AP600 PCS DBA approach Reports and sections addressing the topic
- Road map of DBA approach Road maps have been provided and updated as required during SSAR 6 2.1.1.1 through 6 2.1.1.2 desenbe the review process (see table of meetings provided at July 27, the overau PCS DBA approach.
1995 NRC PCS meetingL The report.*Applicatron of WGOTHIC to,
AP600 PCS DBA.* wdl provide an integrated A road map to PCS DBA boundmg analysis methods has been overview of information provided to NRC provided.
during closure negotstens,includmg
- text discussion according the outline in this Table.
- text covering each accident phase and discussing resolution of each identified phenomenon. (NTO-NRC-95-4545, AGI/95)
- bounding values used for input such as shown in Table 2.
- 1. Complete descripton of WGOTHic Contents should be sufficient to fully describe
NTD-NRC-94-4260
- the derivation of the conservation squations A complete description of GOTHIC has been provided wkhin GOTHIC Containment Analysis Package.
EPRI documents, including a discussion of the conservation Version 3.4e. Volumes I-lil include: Mass equaten equations.
Energy equation The apphcability of GOTHIC 4.0 Momentum equation
- The GOTHIC code has undergone a peer review, and results documentation and peer review results to Equation of state have been provided.
WGOTHIC has been provided, NTO-NRC 4577, NTD-NRC-95-4563 and NTO-NPC e All conservation equations for Climes have been described.
4595.
NTD-NRC-95-4462 EPRI Report RA-93-10. GOTHIC Design Review, Final Report
'i.GNC 5 2.0 Complete description of WGOTHIC upgrat. - to GOTHIC
- the indrvidual models incorporated into the code Heat and mass transfet correlations have been described and WCAP-14382,12.2,2.3. and 14 and WCAP-validated with separate effects and integral tests.
14326 12.0 Include: Empirical correlations (e.g Uchidal identify fixed licensing model models and numencal The set of 6quations necessary to accurately model the PCS have WCAP-14382,12.5, 2.6 values been added as a subroutine set, and are collectrvely called Tlimes." All models have been documented.
Revision 1 November 17,1995 Page 2 of 17
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Topic SSAR AP600 PCS DBA approach Reports and sections addressing the topic
- 2. Joselication ei the Indwiduel Modele The Phenomenon identrhcation and Ranking Table (PIRT)
The apphcations report will seaunawe Tha models should at a minimum include describes all phenomena relevant to containment DBA and include the PCS DBA methods in tables.
provides a ranking of their importance. A road map of the similar to the *.P600 PCS Road Maps (NTD-phenomena in the PIRT and how each is addressed in the DBA NRC-95-4545) for each accident / phase has been provided.
- the neat and mass transfer correlations WCAP-14326.14.2 for evaporation 14.3 for The heat and mass transfer correlations for the external shell condensation.
Example: Brief description of test and test purpose surface contain small, conservatrve biases based on separate What parameters were measured effects tests. Scatter for the dominant phenomenon, mass How does test geometry relate to AP600 transfer has been discussed.
Treatment on entrance effects WCAP-14382,19 Plot WGOTHIC results versus measured data Uncertainty analysis Nominal correlations (with known conservative biases) have been NTD-NRC-95-4570 provides the bases for incorporated into the DBA evaluation model. In addidon, a correlation biases.
conservadve multiplier to bound separate effects data is applied to the heat and mass transhrt correladons on itoside and outside containment.
- the air annulus model Based on momentum and energy scaling at prototypic AP600 WCAP-14382,16 and A-3 describe the dr'ving forces, the external annulus is modelled as a 1D flow modelling methods Example: Pressure drop path. Because of the large downcomer flow area and small Flow and air temperature effects fraction of heat deposited through the baffle 20 effects are WCAP-14190, p.2-6 addresses downcomer Uncertainty analysis adequately accounted for implicit!y in t'io loss coefficient obtained from -1/6 scale air flow tests NTD-NRC-95-4414 RAI 952.102 response referencing specific Since the downcomer represents only 10% of the momentum in scaling WCAP-14190 sections.
the external tion path, performance is not sensidve to reladvely large changes in downcomer characterisdcs. Sansitivines to extemalloss coefficiant show that large changes do not signincantly impact containment pressure. These sensidvities will be documentedin Secdon 7.
Revision 1 November 17.1995 Page 4 of 17 t
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,.o Tope SSAR AP600 PCS DBA approach Reports and sectons addressing the topc
- the water distnbution for coverage and Based on cold full scale tests wrth maximum manufactunng SSAR 6 2.1.1.3 gives DBA water coverage tolerances, cold water coverage as a function of flow rate is assumptions.
Example: Basis for area coverage bounded.
Lack of full scale heated test data NTD-NRC-94-4247 Uncertainty analysis Using a scalable (nondimensional) correlation, the effect of heat Wethod for Determining Fdm Flow Coverage flux is estabhshed, and heated LST data for coverage is bounded for the AP600 Passive Containment Coolmg System," shows the correlation chosen and The DBA also conservatively use a constant flow throughout the its validation, bounding heated LST data transient equivalent to the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> value.
(Figure 2 p 111 Sensrtivities have shown that the containment pressure NTD-NRC-94-4286 performance is not sensitive to water coverage fraction assumed "Supplementalinformation on AP600 PCS in the DBA. This is because of the high sensitivity of Film Flow Coverage Methodology,* includes evaporation rate with increases in containment surface water coverage sensitivrnes (Figure 3, p.11) temperature, coupled with the thermal capacitance of internal structures as heat sinks. Even reducing the already conrervatively bounded SSAR water coverage fraction by a factor of 2 does not cause the design pressure to be exceeded.
- f>!m flow rates.
The PCS DBA fdm flow rate as a function of time conservatively SSAR 6.2.1.1.3 assumes failure of one train of PCS tank drain valves, in addition to single failures assumed in mass and energy releases.
- film delay time Delays in wetting due to heated surface aoplication are negligible SSAR 6.2.1.1.3 provides the SSAR analysis with respect to the conservatism in the assumed delay time.
assumptions.
The appications report will provide the chronology of events leading to external wetting and provide plots of the relevant external containment temperatures.
Justifcation of the assumed delay time, accounting for the heated surface, will be documented.
Justrfication should include the results of Validation with separate effects tests is complete.
WCAP-14382,13 2.1,3.2.2,4 for
- separate effects and summaries.
WCAP-14326 describes separate effects validation and also validation using LST internal data as a separate effects test.
- integral testing Validation with integral tests (LST) is complete.
WCAP-14382. Sections 6,7,8, and to present integral test compansons Revision 1 November 17,1995 Page 5 of 17
Topic SSAR AP600 PCS DBA approach Reports and'sectens ' addressing the topic -
These comparisons should provide both Comparisons with steady state periods during'the LST series Integral test validanon is presented in.
- steady state and have been completed.. These are tests which validate heat and WCAP-14382,18 and Appendix A -
mass transfer predictens aher blowdown, during quasi-steady portions of the transient.
- transient results.
Transient results have been provided for initial pressurizatens WCAP-14382 Sections 6,7,8 and 10 and for subsequent transients imposed per the test matrix.
present integral test comparisons -
Ddforences should be evaluated and reasons for the deviations provided.
Separate effects and integral tested configuration ddlerences The ranges of parameters in AP600 and separate effects and WCAP-14382 Secten 9.2 shows the range from the AP600 design need to be addressed and demonstrated integral tests are stated in both WCAP-14326 and WCAP-14382.
of mass transfer parameters validated by the LST to be applicable.
Scaling of the LST relatwo to the AP600 has shown that the LST
~
can be used for validation of PCS heat and mass transfer WCAP-14326 shows the range of correlatons, and that large scale circulaten through lower parameters covered by separate effects compartment is not well represented by the LST. The potential tests.
for large scale ekculation affects the axial non-condensible distribution and can be accommodated based on sensitivities to See also discussion in box below.
those distnbutions. See also discussion in box below.
i i
Where no separate effects or integral tests for special features Air annulus: see above.
WCAP-14190 identifies all atypicalities such as the air annulus exists, theoretical justificaten should be associated with the LST.
provided to demonstrate conservatwo results will be obtained.
Liquid film eubcoohng: Represents a negligible (5%) heat removal mechanism for AP600.
Since large scale circulation affects the axial
'I density gradient, it will be addressed by the The impact of large scale circulation on the PCS DBA is limited sensitwities to factors which a# set internal i
i to the aust density gradent effect on mass transfer. The eSucts heat sink efficiency during the second oflarge stain circulation through the loseer compartments and jet pressure peak.
l entrainment are conservaeive69 bounded:
l
- for the short seem LOCA and MSLB by conswdd;
(
minimiting sanam access to heat sinks ; and l
- for the kng anrm LOCA 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> by using komped parameter which osermwes noncondensibbs from below deck. penskring I
PCS heat transier.
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Revieson 1 November 17,1995 Page 6 of 17
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.o Topic SSAR AP600 PCS DBA approach Reports and sections addressing the topic
- 3. Lerge Scale Test (LST) Facility Complete description of the facitrty including instrumentation The PCS final test report provides complete detads.
WCAP-14135, Section 2 is test facihty (location and accuracy) and test matrix.
desenptton, including instrumentation The most significant measurement error is the steam flow rate location and accuracy is given in Table 2.2-1 during rapid transients and transient water coverage fracdons.
Measurement uncertainties are understood and bounding approaches for AP600 DBA evaluadon models have been developed.
Final presentation of all test results including an evaluation of Validation of distributed parameter modeling with LST shows WCAP.4382 Sections 6,7,8. and to the data. The presentation of the tests results should be
- pressure is well predicted w'rth a slightly positive bias present integral test comparisons for sufficient to allow consideration of not only pressure profiles but
- boundary conditions used as input to clime heat and mass parameters relevant to the heat and mass also velocity, stratification, temperature distributions, heat and transfer correlations are well predicted based on comparisons of transfer correlations near the vessel shell.
mass transfer rates, and noncondensible distributions.
measured axially distributed temperatures and velocitima near the Also included are 3D temperature shell and non-condensibles at several elevations distributions to show reasonableness of the Need to address:
- internal temperature field is well predicted based on 3D predicted in*ernal fields.
einstrumentation uncertainty in developing boundary input data temperature rake measurements
- steam inlet M&E (fluctuations)
- axially distributed wall heat fluxes are well predicted
- PCS water flow and temperature (fluctuations)
- condensate flow, when applicable Validation of lumped parameter modelling with LST shows that e Instrumentation uncertainty in comparisons of dependent lumped parameter overpredicts velocities inside the vessel and a variables resultant overmixing of non-condensibles. Using free convection e Need to discuss difference in calculation versus test data eliminates the velocity effect. The inherent over-mixing results in
- transient portions of tests need to be considered conservative predictions for the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> cnterion.
- need to present "secuer test data matrix The LST data evaluadons and calculations have confirmed the PIRT important phenomena.
The WGOTHIC validation with LST has provided input to develop a bounding approach for tire AP600 PCS DBA evaluadon model
- 4. 06er -4
" componeens What role can the small scale test program play in WGOTHIC The Small Scale Test program was used in the initial WCAP-13246 (superseded by WCAP-14382) i validation?
development of AP600 PCS DBA methodology, primarily to examine external heat transfer, as discussed in WCAP-13246.
t Since the LST provides prototypical aspect ratio for inside containment and it has been the subject of extensive scaling evaluations,the LST is the focus of final validation of AP600 PCS DBA methodology.
i Revision 1 Novemtxt 17,1995 Page 7 of 17
- .ot "l
repic SSAR AP600 PCS D8A approach Reports and sections addressing the topic L What role does the EPRI emporimental test data base play in the The EPRI comparisons to an extensive test database, as well as AP600 model development?
the GOTHIC code capabihty to perform the more dotaded eHow do the EPRI comparisons justdy the distnbuted distnbuted parameter calculations,were used by Westmghouse parameter modeling techniques for the AP6007 in the decision to use GOTWIC as the startmg point for WG0THIC eHow do the EPRI comparisons justdy the lumped development.
parameter modeling techniques for the AP6007 eTo what extent does Westmghouse rely on EPRI The distributed parameter modehng methodology developed for
.[
development modeing gedelmes and how do they AP500 using WGOTHIC is vahdated by Westmghouse. The apply to the AP6007 AP600 PCS DRA avaluation modoi validahon is based entwely on scaling evaluations and comparisons to tests performed by Westmghouse and provided to the NRC.
The EPRI guidelines for GOTHIC have been used to develop Westmghouse eser guidos for AP600 analysis, and are used in setting up input other than Climes. In addeon to licensing documentahen submitted to NRC guidance to analysts is given by the WGOTHIC User's Guide and the collection of supporting cale notes giving final, specific input item definitions for AP600.
-j Certainly, since the GOTHIC conservation equations have not changed the GOTHIC Technical and Programmer's manuals contmus to provide background.
Thus, while the EPRi GOTHIC User Guido provides valuable background, the AP600 methodology is froren by Westinghouse
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Topic SSAR AP600 PCS DBA approach Reports and sections addressing the topic ur
- 5. Applicesien of LST comparisons to AP500 A complete scaling analysis should be provided to show how the A complete scaling analysis has been provided, showing that the WCAP-14190,is the final scaling report. A comparisons can be applied to AP600. It should reveal areas of -
f cihty is weil scaled for validating heat and mass transfer revision is in progress to address comments mis-scaled parameters as well as the credible ranges of correlations for application to AP600. Onty one signihcant received,includmg RArs. To date, the P/RT parameters of interest. In general, the discussion should atypicality is identified. That is the lack of a flow path into the remains complete for high and medium provide an understanding of how scaling was considered in the simulated steam generator compartment of the LST. This affects importance phenomena. Ths PIRTis being.
evaluation af the data.
large scale circulation through below deck regions. These effects revised to eclude low importance can be directly addressed mth sensitivities to axial non-phenomena for completeness. Revisions to condensible gradient.
the pressure rate of change equation, currentty underway, are expected to con 5rm The scaling of AP600 with respect to the integral LST is used to the conclusions in (10.0 of WCAP-f 4790.
address the relationship of the plant and test with respect to all relevant phenomena and geometries.
Scaling conclusions and identification of Sut6cient instrumentation was included in the LST to show that what can and cannot be validated with the the potential for compensating errors has been adequately LST has been provided INTO-NRC-95-4561).
cddressed.
Supporting sensitivities to parameterr thich affect mixing, will be provided.
Provide WGOTHIC comparisons with the test data. A description Comparisons to separate effects tests and integral tests have WCAP-14382,14 summarizes separate and evaluation of the results and an explanation of differences been provided.
effects tests, and 57 and 8 provide integral should be provided. The present.tions should include a test validation.
discussion of the experimentalinaccuracies and uncertaintes.
The 375 node distributed parameter evaluation modelis validaMd (i.e., inlet steam flow).
in detail with 13 LST steady state points from 6 test runs, including 13 transient pressure increases or decreases.
Transient results ar-presented for detailed local parameters at various elevations, and 3D internal temperature rake comparisons for one test are provided.
An extensive discussion of the steam flow measurement uncertainty for the blind test prediction is provided in WCAP-14382, Appendix B.
Rewsion 1 November 17,1935 Page 9 of 17
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Topic SSAR AP600 PCS DBA approach Reports and sections addressing tne topic Provide an explanation of how these comparisons win be used WCAP-14382 56.4 descnbos the specific noding for AP600 as WCAP-14382 66.4 19.6 in the development of the methodologies to be used in the determined from LST.
required SSAR anal @es for the containment performance.
NTD-NRC-95-4545. AP600 PCS DBA Road t
Maps l
l In particular, the methods used to assure conservative DBA The methods to assure conservative DBA analyses are shown in.
analyses should be provided.
the AP600 PCS 084 road maps provided for inenrnal and external containment processes and for aR accidmt phases.
t k
- s. assess essenspuest ser tsT and APsee Nodalization studies for both LST and AP600 should be provided The nodmg studes in WCAP-14382 55 and Appendix A show WCAP-14387 l
to support the actual AP600 models. The discussion should that the 375 node LST evaluation modeiis weX away from any inck de whether the lumped parameter or the distributed cidfs related to either increased pr decreased noding to indicate Confirmatory noding studies for the AP600 parameter version of the code is used and the justdication for its the eninct of noding and determine if any cMPs due to noding are being perfctmed using WGOTHIC. A use during the seiscted time period for each class of accidents exist WCAP-14382 56.2.1 describes distnbuted parameter summary report of AP600 noding study (LOCA and MSLBl.
noding methodology in detail. 56.4.1 describes its application to conclusions and application to the PCS D84 AP6t1 wiR be provided.
Nodal sensitivity analyses should be provided for each model to i
demonstrate convergence.
The effects of using coarsely noded lumped parameter are
}
discussed in WCAP-14382 55.3. 56.3.1 describes lumped 1
parameter noding methodology. 56.4.2 describes its application to AP600.
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Tepic SSAR AP600 PCS DBA approach Reports and sections addressing the topic
- 7. APtes evoluetes model Justification of initial and boundary conditions (ie., containment Sensitivities have shown that the PCS system is well away from Sensitivities using WGOTHIC f.0 and the temperature, pressure and humid ~ty; PCS water temperature, any chffs in performance, even beyond the bounding DBA June f 992 PCS eva!uadon model showed no r
PCS inlet air temperature; LOCA and MSLB spectrum of mass assumptions. The PCS is self compensating in that increases in signincant chffs in the design for the most and energy release rates).
containment surface temperature result in increased driving important parameters. (March 77,1994 forces for external cooling, and the containment contains a NRC PCS tleeting1.
signifcant amount of thermal capacity due to internal structures.
Con 6rmatory sensitivities using WGOTHiC Sensitivity analyses for individual models need to be provided.
f.2 and the SSAR evaluadon model will be include the PCS water film flow rate. PCS water coverage model, provided. The application report will provide PCS effluent recirculation and shadowing, mixing and sensitivities to stratrfication, and heat sinks.
- time step size
- initial humidity
- initial air mass
- initial temperature
- initial pressure
- initial PCS water temperature
- LOCA and MSLB spectrum of M&E releases The sensitivities will be performed for both LOCA and MSLB and will range parameters about the bounding SSAR values.
Sensitivities will also be confirmed for the following, which may extend beyond the DBA ranges
- PCS water coverage fractions
- PCS water film flow rate
- PCS effluent recirculation
- degree of internal mixing
- internal heat sink area Revision 1 November 17,1995 Page 12 of 17
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Topic SSAR AP600 PCS DBA approach Reports and sections addressing the topic Uncertainty analyses for individual models also need to be.
Bounding DBA cakulations are performed using the evaluation AH uncertainties in significant heat removal provided. Include also heat and mass transfer correlations.
modelas describedin the AP600 PCS DBA Road Maps.
processes have been identified and bounded iNTD-NRC-9S-45451.
- 8. IAsier issues end concess (1) Acceptance of some LST tests for WGOTHIC validation. If The issue of steam flows occurs only for tests wherein the steam A complete discussion of the blind test the instrumentation was not property ranged and boundary flow meter was out of range. The most significant deviation is in steam flows is given in WCAP-14382 conditions had to be d veloped after the test. then there is the blind test. Post test data was used to assess the effects.
Appendix B.
concern t at too much uncertainty exists is the validity of the analysis. To the extreme, program the measured pressure As requested by the NRC, the PCS blind test process was response as the
- boundary
- condition and calculate the established to provide control of the input and code changes.
remaining boundary conditions to obtain the response. The Agreement was made to perform blind test predictions earlier usefulness of the Blind Test as a validation of WGOTHIC comes than planned and to provide the input deck and identify any code into question.
changes throughout the blind test exercise. Westinghouse has met this commitment.
The LST program has provided suthciently accurate information to develop a bounding approach for analyzing AP600.
Revision 1 November 17,1995 Page 13 of 17
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Topic SSAR AP600 PCS DBA approach Reports and sections addressmg the topic (21 k is expected that the margins in dw AP500 are not to be Discussions of the specifics of AP500 PCS methodology and the A'sensitnnty run using AP600 input with.
reduced from those of current generation LWRs.
use of bounding parameters for aR inputs have been ongoing Standard Review Plan (SRP) s(pie methods since early 1994.
will be made for LOCA through. blowdown la) Demonstration of this might include an arialysis of the to provide a snapshot relatwo to SDP 4
AP600 lup to the time of PCS flow) with a currently approved AR inputs used in the PCS DBA are conservative boundt similar methods.
licensing model to show that WGOTHIC is at least as to the approach br existing Aicensed plants.
conservative as an approved model This would necessarily Discussion of the SSAR references to the include a comparison of two computer programs to account for various DBA are in 50 of this Table, different correlatens including an assessment of what could be Margins (conservatisms) have been applied to calculations that deemed a coraservative correlaten versus what could be called a are sufhcient to bound calculation uncertainty when predictmg best estunate correlaten. It might even be necessary to alter PC3 08A performance curves, for comparison to design limits.
WGOTHIC models to be similar to those in the approved model WGOTHIC in both the lumped and the detnbuted parameter Margin t etween the design limits and failure Smits are NTD-NRC-95-4545, AP600 PCS DBA Road modes would have to be evaluated maintained similar to existing operatmg plants 1 Maps (b) M WGOTHIC is a best estinto computer program (to be As preserited in June 29,1995 Senior Management Meeting, the NTD-NRC-95-4545, AP600 PCS DBA Road user e sh consentative boundary condition) then a statencal AP500 PCS D8A is not a best estimate approach. A# siprdcant Maps une artamty analysis (similar to that expected for a revoed processes have been bounded.
Appendix K analysal is required to quannfy uncertamty Included must be a consideration of conservatwo forcing l
functions. For example,if the conservative forcing functens 3
drive a well-mixed containment, then no conclusion reganhng uncertainty due to strabhcaten can be drawn. A best estunate j
ovaluation would include best esemate forcing functens and the uncertamty in those values would be factored into the overaB l~
uncertainty.
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Table 2: PCS DBA Evaluation Model Input Assumptions (see also SSAR 6.2.1.1.3)
GEOMETRIC INPUT PARAMETER BASIS FOR VALUE IN EVALUATION MODEL Internal Free Volume Nominal cold values used which conservatively neglects the 1.5% increase in volume at temperature.
Internal Heat Sinks - Area / Volume Consistent with Revision 7 of the General Arrangement Drawings.The smaller trays, piping, and miscellaneous structures are conservatively ignored.
Intemal Flow Paths - Area / Loss Coefficient Consistent with Revision 7 of the General Arrangement Drawings.The smaller flow paths are ignored.
External Flow Paths - Loss Coefficient Consistent with Revision 7 of the General Arrangement Drawings. Loss coeffi-cients based on 1/6 scale annulus pressure drop test.
INITIAL CONDITION INPUT BASIS FOR VALUE IN EVALUATION MODEL PARAMETER -
InitialInternal Atmosphere Temperature Set at maximum Technical Specification value. This acts to maximize the tem-perature of the internal heat sinks.
InitialIntemal Atmosphere Pressure Set at maximum Technical Specification value. This maximizes the initial pres-sure and the amount of air initially inside containment and retards mass transfer.
InitialInternal Atmosphere Humidity Set at 0% relative humidity. This maximizes the amount of air inside contain-ment.
Initial Internal Heat Sink Temperature Set at maximum Technical Specification internal atmosphere temperature. This acts to maximize the temperature of the internal heat sinks and minimizes heat storage capacity.
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INITIAL CONDITION INPUT BASIS FOR VALUE IN EVALUATION MODEL PARAMETER External Atmosphem Teraperature Set to the maximum safety air temperature limit defined by the site interface parameters presented in SSAR Chapter 2.
External Atmosphere Pressure Set to standard,14.7 psia External Atmosphere Humidity Set to approximately 20% relative humidity based on limits defined by the siw interface parameters presented in SSAR Chapter 2.
LOCA MASS & ENERGY INPUT BASIS FOR VALUE IN EVALUATION MODEL PARAMETER RCS Initial Conditions Assumed to be at the maximum expected operating temperature and pressure.
Includes allowances for error and instrument dead band.
RCS Volume RCS coolant volumes incmased by 1.4% for uncertainty and 1.6% for thermal expansion.
Core Stored Energy Core stored energy conservatively increased by 15%.
Steam Generator Mass Inidal mass conservatively increased by 10%.
Initial Power Ixvel 102% of full tech spec. power, accounting for calorimetric error Zirc-Water Reaction 1% of the zirconium conservatively assumed to react. Bounds SSAR Chapter 15 results of no appreciable z'.rc-water reaction.
Steam Generator Heat Release As;umed to occur over i hour, as done in curmnt licensed methodology pre-senteo b We A_P-!G325-P-A.
LOCA Mass and Energy Releases SATAN 78, WCAP-10325-P-A MSLB Mass and Energy Releases LOFTRAN WCAP-7907-P-A Revision i November 30,1995 9-41 am Page 16 of 17
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PCS INPUT PARAMETER BASIS FOR VALUE IN EVALUATION MODEL i
InitialTemperature Containment shell initialized uniformly to maximum Technical S cification value. Conservatively bounds initial temperature profile of shell.
Extemal Film Flow Rate Film flow rate based on assumed single failure of one of two PCS drain tank headers.
Extemal PCS Liquid Film Temperature Film temperature set to upper bound value of 120*F. His minimizes the sub-cooling benefit.
i Film Coverage Fraction Coverage fractions held constant at values calculated after 26 hours3.009259e-4 days <br />0.00722 hours <br />4.298942e-5 weeks <br />9.893e-6 months <br /> of transient operation. His neglects earlier higher coverage fractions which would arsuit from the higher earlier PCS flow rates.
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PCS Material Properties Conductivity of the Carbo-Zine paint reduced to 25% of nominal value for the lumped parameter analyscs.
PCS Emissivity Surface emissivities reduced to 90% of nominal values.
PCS Coatings Thickness Maximum coating thicknesses used.
PCS Initial Delay Time No credit taken for partial film coverage and cooling prior to 11 minutes after initiation of event. Conservatively neglects approximately 5 minutes of cover-age and cooling when water is first applied and coverage develops.
Intemal Heat and Mass Transfer Conclation Free convection only is assumed.
j Extemal Heat and Mass Transfer Correlation Mixed convection assumed.
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