april 1983 international standard problem 13 (loft ... · april 1983 international standard problem...
TRANSCRIPT
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EGG-NTAP-6276April 1983
INTERNATIONAL STANDARD PROBLEM 13(LOFT EXPERIMENT L2-5)PRELIMINARY COMPARISON REPORT
J. D. BurttS. A. Crowton
Idaho National Engineering LaboratoryOperated by the U.S. Department of Energy
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This is an informal report intended for use as a preliminary or working document
Prepared for theU I S I NUCLEAR REr,lJL.~TORY Cor1MISSIO~Under DOE Contract No. DE-AC07-76ID01570FIN No. A6047
n~~ EGr:..G Idaho
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INTERNATIONAL STANDARD PROBLEM 13(LOFT Experiment L2-5)
PRELIMINARY COMPARISON REPORT
J. D. BurttS. A. Crowton
Published April 1983
EG&G Idaho, Inc.Idaho Fa 11 s, Idaho 83415
Prepared for theU.S. Nuclear Regulatory Commission
Washington, D.C. 20555Under DOE Contract No. DE-AC07-76ID01570
FIN No. A6047
EGG-NTAP- 6276
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ABSTRACT
LOFT Experiment L2-5 was designated International Standard Problem 13by the Organization for Economic Cooperation and Development. Comparisonsbetween measurements from Experiment L2-5 were made with calculations from11 international participants using five different computer codes. LOFTExperiment L2-5 simulated a double ended guillotine cold leg rupture of aprimary coolant loop of a large pressurized water reactor, coupled with aloss of offsite power.
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SUMMARY
The Organization for Economic Cooperation and Development designatedLoss-of-Fluid Test (LOFT) Experiment L2-5 as International StandardProblem 13. Calculations were submitted by 11 participants using fivecomputer codes. Eight calculations were preceded by model submittals andqualified as blind calculations. The four remaining calculations wereclassified as open submittals. Comparisons were made between participantcalculations and measurements from Experiment L2-5.
Experiment L2-5 simulated a double ended offset shear guillotine coldleg rupture in a large pressurized water reactor. A loss of offsite powerwas also simulated with a reactor coolant pump trip and an emergency corecoolant system injection delay.
The participants calculated the hydraulic response of L2-5 adequately,except where there were obvious modeling problems. Densities werecalculated adequately in the sections where condensation did not occur.Break flows were generally over predicted. Clad temperature heatups werecalculated adequately but quench times for cladding was predicted less well.
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CONTENTS
ABSTRACT .
SUMMARY .
1. I NTRODUCTION .
2. LOFT EXPERIMENT L2-5 DESCRIPTION ............................•....
2.1 System Descri pt ion .
2.2 Test Conditions ..
2.3 Initial Conditions ..
3. SUMMARYOF PARTICI PANT MODELS .
3.1 Gesellschaft fur Reaktorsicherheit (GRS) .
3.2
3.3
Japan Atomic Energy Research Institute (JAR)
Japan Atomic Energy Research Institute (JAT)
3.4 Central Electricity Research Laboratories (CERL) .
3.5 Studsvik Energiteknik AB (STUD) .
3.6 Eidgenossisches Institut fur Reaktorforschung (EIR) .
3.7 Los Alamos National Laboratory (LANL) .
3.8 ENEL-CRTN .
3.9 Dipartimento di Construzioni Meccaniche e Nucleari( DCMN) .
3.10 Commissariat A llEnergie Atomique (CEA) .
3.11 Technical Research Center of Finland (VTT) .
4. SUMMARYOF BLIND PREDICTIONS .
4.1 Sequence of Events .
4.2 Pressure
4.3 Fluid Temperature ..
4.4 Fluid Density
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4.5 Mass Flow 264.6 Pump Speed 324.7 Rod Temperatures...................... 404.8 Summa ry 40
,
5. SUMMARY OF OPEN PREDICTIONS . 44
5.1
5.2
Sequence of Events .Pressure
44
445.3 Fluid Temperature.......................................... 485 .4 Flu id De nsity 485.5 Ma ss Flow 525.6 Pump Speed 575.7 Rod Temperatures 575.8 Summary..... 61
6.
7.
CONCLUSIONS AND RECOMMENDATIONS .REFERENCES .
62
63
APPENDIX A--PARTICIPANT NODALIZATION DIAGRAMS......................... 64
FIGURES
1.
2.
3.
4.
5.
6.
Comparison of measured and calculated pressurizer pressurefor the bl ind calculations .Comparison of measured and calculated intact loop cold legpressure for the blind calculations .Comparison of measured and calculated broken loop hot legpressure for the blind calculations .Comparison of measured and calculated broken loop cold legpressure for the blind calculations .Comparison of measured and calculated upper plenum pressurefor the bl ind calculations .Comparison of measured and calculated steam generator secondarypressure for the blind calculations .
v
13
14
15
16
17
18
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7. Comparison of measured and calculated upper plenum fluidtemperature for the blind calculations . 19
8. Comparison of measured and calculated lower plenum fluidtemperature for the blind calculations........................... 21
9. Comparison of measured and calculated intact loop cold legtemperature for the blind calculations........................... 22
10. Comparison of measured and calculated intact loop hot legtemperature for the blind calculations........................... 23
11. Comparison of measured and calculated pressurizer temperaturefor the blind calculations....................................... 24
12. Comparison of measured and calculated steam generatorsecondary temperature for the blind calculations 25
13. Comparison of measured and calculated intact loop cold legdensity for the blind calculations............................... 27
14. Comparison of measured and calculated intact loop hot legdensity for the blind calculations............................... 28
15. Comparison of measured and calculated broken loop cold legdensity for the blind calculations . 29
16. Comparison of measured and calculated broken loop hot legdensity for the blind calculations............................... 30
17. Comparison of calculated core inlet flowsfor the bl ind calculations....................................... 31
18. Comparison of measured and calculated broken loop cold legbreak mass flow rate for the blind calculations ..
19. Comparison of measured and calculated broken loop hot legbreak mass flow rate for the blind calculations ..
20. Comparison of measured and calculated integrated break flowfor the bl ind calculations ..
21. Comparison of calculated reactor vessel mass inventoryfor the blind calculations ..
22. Comparison of measured and calculated HPIS flowfor the bl ind calculations ..
23. Comparison of measured and calculated LPIS flowfor the bl ind calculations .
24. Comparison of measured and calculated reactor coolant pumpspeed for the blind calculations .
33
34
35
36
37
38
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vi
.........
25. Comparison of measured and calculated rod cladding temperatureat the 0.76 m elevation for the blind calculations 41
26. Comparison of measured and calculated rod cladding temperatureat the .99 m elevation for the blind calculations................ 42
27. Comparison of measured and calculated pressurizer pressurefor the open calculations........................................ 45
28. Comparison of measured and calculated intact loop cold legpressure for the open calculations............................... 45
29. Comparison of measured and calculated broken loop hot legpressure for the open calculations............................... 46
30. Comparison of measured and calculated broken loop cold legpressure for the open calculations............................... 46
31. Comparison of measured and calculated upper plenum pressurefor the open calculations 47
32. Comparison of measured and calculated steam generator secondarypressure for the open calculations ~...... 47
33. Comparison of measured and calculated upper plenum fluidtemperature for the open calculations............................ 49
34. Comparison of measured and calculated lower plenum fluidtemperature for the open calculations............................ 49
35. Comparison of measured and calculated intact loop cold legtemperature for the open calculations............................ 50
36. Comparison of measured and calculated intact loop hot legtemperature for the open calculations............................ 50
37. Comparison of measured and calculated pressurizer temperaturefor the open calculations 51
38. Comparison of measured and calculated steam generatorsecondary temperature for the open calculations.................. 51
39. Comparison of measured and calculated intact loop cold legdensity for the open calculations................................ 53
40. Comparison of measured and calculated intact loop hot legdensity for the open calculations................................ 53
41. Comparison of measured and calculated broken loop cold legdensity for the open calculations................................ 54
42. Comparison of measured and calculated broken loop hot legdensity for the open calculations................................ 54
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43. Comparison of calculated core inlet flowsfor the open ca 1 cul at ion s . 55
44. Comparison of measured and calculated broken loop cold legbreak mass flow rate for the open calculations 55
45. Comparison of measured and calculated broken loop hot legbreak mass flow rate for the open calculations 56
46. Comparison of measured and calculated integrated break flowfor the open calculations........................................ 56
47. Comparison of calculated reactor vessel mass inventoryfor the open calculations 58
48. Comparison of measured and calculated HPIS flowfor the open calculations........................................ 58
49. Comparison of measured and calculated LPIS flowfor the open ca 1 cul at ions 59
50. Comparison of measured and calculated reactor coolant pumpspeed for the open calculations.................................. 59
51. Comparison of measured and calculated rod cladding temperatureat the 0.76 m elevation for the open calculations . 60
52. Comparison of measured and calculated rod cladding temperatureat the .99 m elevation for the open calculations................. 60
TABLES
1.
2.
3.
Initial conditions for LOFT Experiment L2-5 ..
Summary of ISP-13 participants .
Measured and calculated sequence of events for LOFTExperi ment L2-5 : .
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1. INTRODUCTION
Experiment L2-5, conducted in the Loss-of-Fluid Test (LOFT) wasidentified by the Organization for Economic Cooperation and Development(OECD) as International Standard Problem 13 (ISP-13). This reportdocuments the comparisons between participant computer code calculationsand measured results from LOFT Experiment L2-5. The results fromExperiment L2-5 are documented in Reference 1.
LOFT Experiment L2-5 simulated a double ended, off-set shear,guillotine cold leg rupture. The reactor coolant pumps were tripped anddecoupled from their flywheels within 1 s after break initiation,simulating a loss of offsite power. Consistent with this loss of power,the high and low pressure emergency core coolant injection systems weredelayed. The system description and initial conditions are presented inSection 2.
The purpose of this preliminary report is to present directcomparisons between the calculated parameters and LOFT L2-5 data. It i.sbeyond the scope of this report to assess and analyze the reasons fordiscrepancies that occurred. A more detailed discussion of the comparisonswill be included in the final comparison report after all the participants'comments have been received. The models used by the participants aresummarized in Section 3. The eight blind calculations are compared withmeasurements and discussed in Section 4. Section 5 presents the comparisonbetween measurements and results from the four open calculations.Section 6 contains the conclusions and recommendations drawn from thecomparisons. Appendix A provides a nodalization diagram for each submittal.
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2. LOFT EXPERIMENT L2-5 DESCRIPTION
Experiment L2-5 was conducted on June 16, 1982 in the LOFT facility.The LOFT facility is located at the Idaho National Engineering Laboratory(INEL) and was operated for the United States Nuclear Regulatory Commissionby the Department of Energy at the time of the experiment. This sectiondescribes the LOFT facility and presents the initial test conditions.
2.1 System Description
The LOFT system configuration for Experiment L2-5 is shown inFigure 1. The major components of the LOFT system are: a reactor vesselincluding a core with 1300 unpressurized nuclear fuel rods with an activelength of 1.67 m; an intact loop with a pressurizer, steam generator, twopumps arranged in parallel, and piping connected to the break planeorifice; a broken loop with a simulated pump, simulated steam generator,two break plane orifices, two quick opening blowdown valves (QOBVs), andtwo isolation valves; an emergency core coolant system consisting of twoaccumulators, a high pressure injection system and a low pressure injectionsystem; and a blowdown suppression system consisting of a header andsuppression tank. The details of the LOFT system and instrumentation arepresented in Reference 2.
2.2 Test Conditions
After operating the reactor at 36.0 MW for 40 effective full powerhours to build up a fisson decay product inventory, Experiment L2-5 wasinitiated by opening the two QOBVs, in the broken loop hot and cold legs.The primary coolant pumps were tripped by the operators at 0.94 t 0.01 s.The pumps were not connected to their flywheels during the coastdown. Highpressure injection and low pressure injection were delayed to 24 sand37 s, respectively, to simulate the delay expected for a PWR emergencydiesel to begun delivering power (in response to a loss of site power).
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2.3 Initial Conditions
A summary of the measured system conditions immediately prior toExperiment L2-5 initiation is shown in Table 1. The mass flow rate in theintact loop was 192.4 t 7.8 kg/so The intact loop hot leg pressure was14.94 t .06 MPa. The intact loop hot leg temperature was 589.7 t 1.6 K.The initial core power was 36. t 1.2 MW with a maximum linear heatgeneration rate of 40.1 t 3.0 kW/m.
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TABLE 1. INITIAL CONDITIONS FOR LOFT EXPERIMENT L2-5
Parameter Measured Value
Primary Coolant System
:t:t
7.80.064.01.6
:t 15
192.4 :t14.94 :t
556.6589.7668.0
Mass flow (kg/s)Hot leg pressure (MPa)Cold leg temperature (K)Hot leg temperature (K)Boron concentration (ppm)
Reactor Vessel
Power level (MW)Maximum linear heat generation
rate (kW/m)Control rod position (above
full-in position (m)
36.0 :t 1. 240.1 :t 3.0
1.376:t 0.01
Pressurizer
Steam volume (m3)Liquid volume (m3)Liquid temperature (K)Liquid level (m)
0.32 :t 0.020.61 :t 0.02
615.0 :t 31.14 :t 0.03
Broken LoopCold leg temperature near
reactor ve s se 1 (K)Hot leg temperature near
reactor vessel (K)
554.3 :t 4.2
561.9 :t 4.3
Steam Generator Secondary Side
Liquid temperature (K)Pressure (MPa)Mass flow (kg/s)
547.1 :t5.85 :t
19.1 :t
0.80.060.4
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3. SUMMARY OF PARTICIPANT MODELS
Calculations were received from 11 participants of which eight werepreceded by model submittals to qualify as blind calculations. Table 2lists the participants and the identifier used for each participant in thisreport. Five different computer codes were used in the calculations.RELAP4/MOD6 was used in seven of the calculations and RELAP5 used in twoanalyses. Codes other than RELAP4 are identified as such on eachcomparison plot. Nodalization diagrams for each participant are containedin Appendix A. The following discussion briefly summarizes the model ofeach participant.
3.1 Gesellschaft fur Reaktorsicherheit (GRS)
GRS used the DRUFAN 02 computer code to perform the blindcalculation. The thermal hydraulic models in DRUFAN 02 are based on thesolution for conservation of liquid mass, vapor mass, overall energy, andoverall momentum. Determination of the critical flow at the break was madeusing a one dimensional nonequilibrium model which uses the geometry of thebreak path. The GRS calculation was terminated at 28.76 s after breakinitiation.
3.2 Japan Atomic Energy Research Institute (JAR)
The JAERI Division of Nuclear Safety Evaluation used an improvedversion of RELAP4/MOD6 for their blind calculation. Most of the majormodifications to the code were developed for small break analyses, so thecode used in the ISP-13 calculation was essentially equal to the originalRELAP4/MOD6 code. Critical flow was calculated using Henry-Fauske/HEM witha discharge coefficient of 0.85 for both the subcooled and saturatedregion. The calculation was terminated 50 s after initiation of the break.
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TABLf 2. SUMMARY OF ISP-13 PARTICIPANTS
OrganizationGesellschaft fur Reaktorsicherheitmbh Forschungsgeland(West Germany)Japan Atomic Energy ResearchIn st ituteJapan Atomic Energy ResearchInstituteCentral Electricity ResearchLaboratories(United Kingdom)Studsvik Energiteknik AB(Sweden)Eidgenossisches Institute furReaktorforschung(Switzerl and)Los Alamos National Laboratory(USA)
ENEL-CRTN(Italy)Dipartimento di ConstruzioniMiccaniche e Nucleari(Italy)Commissariat A 1 'Energie Atomique(France)
Technical Research Centre ofFinland
ParticipantF. SteinhoffW. Winkler
F. TanabeK. YoshidaM. AkimotoM. HiranoA. H. Schriven
O. Sandervag
S. Guntay
T. Knight
L . Bell aF. Dona tin iM. Mazzini
R. PochardY. Macheteau
H. HolmstromV. Yrjola
6
Code 10
DRUFAN 02 GRS
RELAP4/MOD6 JAR
THYDE-Pl JAT
RELAP4/MOD6 CERL
RELAP5/MODI STUD
RELAP4/MOD6 EIR
TRAC-PD2 LANL
RELAP4/MOD6 ENEL
RELAP4/MOD6 DCMN
RELAP4/MOD6 CEA
RELAP5/MOD1, VTTcycle 19
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3.3 Japan Atomic Energy Research Institute (JAT)
The Nuclear Safety Code Development Laboratory at JAERI performedtheir blind calculation with THYDE-P1. The critical flow model used themodified Zaloudek and Moody correlations in the calculation with a Moodydischarge coefficient of 0.6. Only the average core channel was modeledwith THYDE-P1; no hot channel analysis was performed. The calculation wasterminated 69.84 s after the initiation of the break.
3.4 Central Electricity Research Laboratories (CERL)
The CERL blind calculation was performed with RELAP4/MOD6. Criticalflow was calculated using Henry-Fauske/HEM with a multiplier of 0.875 and atransition quality of 0.025. Separate hot pins and reflood models wereused in conjunction with the average core blowdown model. The calculationwas terminated 37 s after break initiation.
3.5 Studsvik Energiteknik AB (STUD)
Sweden1s blind submittal of ISP-13 was performed using RELAP5/MOD1,Cycle 14. The RELAP5 critical flow model was used with a dischargecoefficient of 0.87. The calculation was terminated 55 s after the breakinitiation.
3.6 Eidgenossisches Institut fur Reaktorforschung (EIR)
EIR performed both a blind and an open calculation for ISP-13 usingRELAP4/MOD6. For the blind calculation only a single core volume was used;in the open calculation, two parallel, multivolume core channels weremodeled. Except for the core, the blind and open models were identical.Critical flow was calculated using Henry-Fauske/HEM, with multipliers of0.8 and 0.848 respectively. The blowdown portions of the calculations wereterminated at 44 s, while separate reflood calculations were run out to100 s.
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3.7 Los Alamos National Laboratory (LANL)
The open calculation of ISP-13 submitted by LANL was performed usingthe TRAC-PD2/MOD1 computer code. TRAC-PD2 features a three dimensionaltreatment of the reactor vessel, two phase nonequilibrium hydrodynamicmodels and flow regime-dependent constitutive equations. The code does notcontain a critical flow model; break flow was calculated using breakgeometry and normal field equations in the code. The LANL calculationwas terminated 100 s after break initiation.
3.8 ENEL-CRTN
The ENEL blind calculation was performed with RELAP4/MOD6. The modelused two parallel, multivolume core channels, representing the average andhot channels. Henry-Fauske/HEM was used to calculate critical flow, withmultipliers of 0.865 and 0.7 for subcooled and saturated flow respectively.The long term calculation was terminated at 160 s after break initiation.Due to problems with the output tape, only the short term plots (0-30s)were available for the comparisons in this report.
3.9 Dipartimento di Construzioni Meccaniche e Nucleari (OCMN)
OCMN performed an open calculation of ISP-13 using RELAP4/MOD6.Critical flow was modeled with Henry-Fauske/HEM with discharge coefficientsof 0.84. Transition quality was set at 0.003. The M006 heat transferpackage (HTS2) was used in the calculation. The calculation was terminated30 s after break initiation.
3.10 Commissariat A 1 IEnergie Atomique (CEA)
The CEA blind submittal was performed using RELAP4/MOD6. Henry-Fauske/HEM was used to model critical flow, with discharge coefficients of 1.0 anda transition quality of .0025. The calculation was terminated 56 s afterbreak initiation.
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3.11 Technical Research Center of Finland (VTT)
The VTT open calculation was performed using RELAP5/MOD1, Cycle 19.Updates to the FIDRAG subroutine, which calculates the drag between fluidphases, were added. A discharge coefficient of 0.84 was applied to theRELAP5 critical flow model. The calculation was terminated 60 s after thebreak was initiated.
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4. SUMMARY OF BLIND RESULTS
Eight ISP-13 submittals were designated blind calculations. Thisdesignation was given to those participants who submitted the models to beused in the calculation prior to the performance of experiment L2-5. Thecomparison of these calculations with measured data is presented in thefollowing sections.
4.1 Sequence of Events
The measured and calculated sequence of events for L2-5 are summarizedin Table 3. The experiment was initiated by opening the two QOBVs. Theprimary coolant pumps were turned off and the primary coolant systemdepressurized to saturation, both by 1 s. The cladding temperatures in thecentral fuel assembly departed from saturation within 2 s. Accumulatorinjection began at 16.8 s. The maximum cladding temperature of 1077 K(1479°F) was reached at 28.5 s, just prior to the completion of lowerplenum refill. High pressure injection (HPI) initiated at 23.9 s; lowpressure injection began at 37.3 s.
Most of the blind calculated sequence of events were in accord withdata. The calculated end of subcooled blowdown ranged from 0.05 s (STUD,CEA) to 0.09 s (JAR). Reactor scram ranged from 0.0 s (ErR) to 0.25 s(STUD). Cladding temperatures began to deviate from saturation between0.51 s (STUD) and 1.42 s (EIR). Both Japanese submittals tripped thereactor coolant pumps early, at the time of the break. The participantscalculated pressurizer voiding between 5.0 s (ENEL) and 17 s (CEA),compared to the 15.4 s seen in the data. Accumulator initiation rangedfrom 12.8 (STUD) to 19.3 s (ENEL). The time of maximum peak cladtemperatures calculated by the participants deviated significantly fromdata, ranging between 10 s CGRS and 50 s (ENEL). Only CERL's calculationreached a peak within 5 s of data at 24.0 s but their peak clad temperatureof 1155 K (1600°F) was significantly higher.
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TABLE 3. MEASURED AND CALCULATED SEQUENCE OF EVENTS FOR LOfT EXPERIMENT L2-5:;
Event L2-5 ~ CERL -U!L ENEL GRS ->1AL STUD ~ LANL -U!L DCMN VTLL2-5 initiated 0.0 0,0 0.0 --a -- 0.0 O. 0.0 O. 0.0 0.0 0.0 0.0
... ;}:;.. SlilJCOOled b Iowdowll 0.043 0.09 0.056 0-.1 -- 0.07 -- 0.05 .05 -- o. - . 1 -- .06... :: ended
: ..,..:.Henctof' scrammed 0.2L. O. 11 0.24 0,0 .1 0.097 -- 0.251 .211 .211 0.0 .2111 .1.. '
Clad tempe r'ltllres 0.91 1. 15 0.8 1.112 -- 0.67 -- 0.51 -- 1.0 1.42 .9 .5deviate fromsatur"ation
,RCP trip 0,911 0.0 0.94 1.0 .9 0.0 0.951 .24 1.0 .9111 .9'11.0 .911Subcoo Ied b rea k 3. II 3.011 4. 1 -- 3.3 3.3 -- 4.0 -- It-O -- 3.5 11.0rlow elld
". ,".:. PZf~ emptiel1 15,4 14. II 10.2 -- 5.0 12.1 -- 15.0 17. 16.5(95%) 8.0 15.3 15.028.0(99%)
Accumul<ltor 16.8 17.36 16.8 13.8 19.3 16.02 17 .0 12.85 15.2 17.75 15-16 16.6 16.3in it ia ted"P I initi<lted 23.9 211.8 24.0 22.0 23.9 211.05 22.25 23.91 24.4 23.9 22.0 23. 91 211.0~IClX i mum PC 28,/17 48.8 211.0 -- 50.0 10.0 -- 12.85 -- 50.0 38.0 -- 5.2tempe ra t II rereitched...
LP I in it i<I ted 37.32 35.0 37.0 -- 37.3 -- 3".75 37.31 36.3 37.32 35.0 -- 37" 2
a. -- = not calculated.
4.2 Pressure
The comparison between calculated pressurizer pressure and data ispresented in Figure 1. JAR and CEA calculated a pressurizerdepressurization slower than that seen in the experiment, while all otherparticipants calculated a faster depressurization with STUD's calculatedrate being the most severe. ENEL's calculation apparently included theisolation of the pressurizer component at 5.0 s.
Comparisons of pressure for the intact loop cold leg, broken loop hotleg, broken loop cold leg, and upper plenum are shown in Figures 2through 5, respectively. Generally all participants, except ENEL,calculated pressure histories below that actually observed in the data.ENEL's calculation was consistently high out to 30 s. STUD again had thelowest pressures over all. The CEA calculation displayed some interestingdiscrepancies. Their calculation of cold leg pressures, both broken loopand intact loop were extremely close to data. However, the broken loop hotleg pressure calculated by Mssrs. Pochard and Macheteau showed an initial5 MPa (725 psi) pressure drop below that of all the other participants. Inthe upper plenum, the CEA pressure history was decidedly higher than therest of the calculations. Analyzing the reasons for this pressurediscrepancy is beyond the scope of this preliminary report.
Comparison of the steam generator secondary pressure (Figure 6) wascomplicated by the range of initial conditions used in the calculations.STUD, GRS, and CEA all underpredicted the equilibrium pressure in thegenerator. JAR's initial pressure was much higher than data, butstabilized out only slighty high. JAT's and CERL's equilibrium pressureexceeded data substantially. EIR1s calculation predicted the secondarypressure response quite well.
4.3 Fluid Temperatures
Calculated upper plenum temperatures when compared to data in Figure 7showed the saturation temperatures corresponding to the respective pressure
12
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5000
~ rSOOJ ~-d~()--Il-O-'I-----: 0
0 10 20 30 40 50Time (s)
500
I~2500
I
12000
~
J1500 :;
I ~I I/l
~ 1000 ~0....
GRS (DRU)JA T (THY)STUD (R5)CEAPE-8L-002
- -h- - . -.-- - . - - .-
1-oo6.
o10 20 30 40 50
Time (s)Figure 3. Comparison of measured and calculated broken
loop hot leg pressure for the blind calculations.
10000
5000
20000 II
~fI
15000 illi
Q)l...
::lIIIIIIQ)
l...
0....
15
. ~:...~:.......
.. : : ~..:.~':. . .. ....... :....~~.<:. ::: "
20000
500
-,......- ....... - ------- - - -- --
JAR0 CERL 25000 EIR6. ENEL
PE-BL-OOl ............2000 0
(IJ
Q..........,
1500 Q)...:l(IJ(IJ
1000 Q)...0....
o504020 30
Time (5)10
15000 '--00....J..........,
Q)10000...
:lrJl(IJ
Q)...0....
5000
20000 II
~I
I15000 qr
1&
o,0
6.
GRS (DRU)JA T (THY)STUD (R5)CEAPE-BL-001
I~2500I
~2000
............o(IJ
Q..........,
Q)...:l(IJ(IJ
Q)...0....
0 10 20 30 40 50Time (5)
Figure 4. Compari son of measured and calculated brokenloop cold leg for the b Ii nd calculations.
'-"-- ..pressure
16
,'; ::..: .....
20000
J2S00JAR
0 CERL0 EIR
'6. ENEL15000 1-- PE-1UP-001A 1
I 2000"..-....
"..-.... 00 I0... (/)~ a.'-''-../
CV10000 1500 CD
'-:J L
(/) :Jen enCD
(/)
1000 - CDL
0-L
0...5000
500
'---.,.""I'\.--,~
0 a0 10 20 30 40 50
Time .(5 )
20000
15000...........0
0...~'-"
Q)10000L
:J(/)
enQ)L0-
5000
oo6.
GRS (DRU)JAT (THY)STUD (RS)CEAPE-1UP-001A1
~2S00l 2000
1500
11000
1500I
CDL:JenenQ)L
0...
o 0o 10 20 30 40 50Time (s)
Figure 5. Ccmparison of measured and calculated upperplenum pressure for the blind calculctions.
17
', .. ".:.,:',' .. :.;, '" ....:: .. :' . "'-';"::. :
7000
6500
JARo CERLo EIR
PE-SGS-OOl
1000
950
(j)I.....
:JV1V1(j)I.....
0....
(f)
Q."-"
900
1
850
1""0~750
5000 lL "'--- --'- --'--- ---' io 10 20 30 40 50
Time (5)
5500
7000GRS (DqU) 1000
0 JA T (THY)0 STUD (R5)
6500 6. CEA r950,.-.... PE-SGS-001 l ..........,0 0
0....I 900 (f)~ Q."-'" J "-"
(j) 6000 (j)l... /J850 l...::J ::J(/)(/)
(f)
(j)(f)
(j)l... -- ...... ' I.....
0.... . 'v ~::::."" ......... -
0....5500 800
750
5000o
Figure 6.
10
Compari songenerator
20 30 40 50Time (5)
of measured and calculated steamsecondary pressure for the blind calculations.
18
. ',. ~'.
650 700JAR
,.......... 0 CERL ,..........
:::.:::600 0 EIR u..0
'-" 6 ENEL r600 '-"
Q;l TE-1UP-001 IQ)
L~
L
:::l 550 ~ ::::J...... 5000 0L L
Q;l Q)
a. 500 Q.
E EQ;l 400 Q)
......-+- 450 ......c c0 0- 3000 00 400 0() ()
200350
0 10 20 30 40 50Time (s)
1- GRS (DRU) f7000 JA T (THY) ,..........0 STUD (R5) "I 600 ~6 CEA '-"
TE-1UP-001 Q)L::::J
500 0LQ)CL
'""\..- E/ ' 400 Q)
......c0
00()
200
20 30 40 50Time (s)
Figure 7. Comparison of measured and calculated upperplenum fluid temperature for the blind calculations.
650
260J'-" '
Q;lL:::l 550......0LQ)
a. 500EQ)
-+- 450c0
00 400()
350a 10
19
';' .... ::. ", .'."" ..'. '.';
.; :',.'; .~..
histories. Ony ENEL and CEA fluid temperatures were consistently abovedata. Superheated fluid appeared in the data around 28 s. Several of theparticipants registered superheat at various times, ranging from 20 s(CERL) to 37 s (JAR). ENEL showed no superheat on the data plots, buttheir report plots show superheat beginning around 40 s. JAT, STUD and CEAshowed no superheat at all in their upper plenum temperature histories.
Figure 8 compared calculated lower plenum temperatures with data,again showing the saturation temperature correspondence discussed above.JAR's RELAP4 calculation showed considerable superheat in the lower plenumstarting at 27 s and quenches at 39 s. The JAT THYDE-P1 analysisregistered an abrupt 68 K (124°F) drop in their temperature at 42 s, theonly participant to calculate subcooling in the lower plenum.
In the intact loop cold leg temperature comparisons, seen in Figure 9,there was considerable variance in the fluid temperatures. None of theparticipants calculated the oscillatory behavior seen in the test. Mostcalculated some subcooling with GRS and JAT being the most pronounced,dropping to 310 K (100°F) at 20 s (GRS) and 31 s (JAT). The temperaturedrop in GRS, ENEL, and CERL appeared to correspond to the initiation ofaccumulator flow. There was no immediately available explanation for thedrops seen by STUD and JAT.
Comparison of measured and calculated intact loop hot leg temperaturesis presented in Figure 10. The LOFT experiment experienced somesuperheating in the hot leg around 28 s. Superheat was calculated by CERL(23 s), JAR (38 s) and JAT (34 s). None of the other participantscalculated this superheating in the intact loop hot leg.
Pressurizer average temperature, shown in Figure 11 was underpredictedby all participants. This does not include the isolated pressurizer modelused by ENEL.
The steam generator secondary temperatures, presented in Figure 12,reflect the various initial conditions used by the participants. Ingeneral the blind calculations, with the exception of JAT, remained abovethe equilibrium L2-5 temperature.
20
{
, ... ;jJ;~,.,'. ", -, ......:: ....)j.... .'~~v
\'.'-.' ."
.: .:' ......... ;.... .. :.'
". ,:". :-. ," .
800JAR
,--... 0 CERL ,--...~ 0 EIR lL.'---'700 800 0
t::, ENEL '--"
<D TE-1LP-OOlI...
600 1 cv
= I...
-+-:::l
0 V 0I... /600<D '!~ I...
Q. ~ c_ l])
~ 500 lQ.
UEl])
~ 40J
1_ 400 -+-C0-0
U 300 1 [2000U
I
0 10 20 30 40 50Time (5)
1_- GRS (DRU)0 JA T (THY) ...--...0 STUD (RS) u...
0
t::, CEA ro '--"
TE-1LP-OOl cvI...:::l
-.j 0
1600 I...l])Q.
Ecv
400-+-C0
, ------.~00
200 U
20 30 40 50Time (5)
Figure 8. Comparison of measured and calculated lowerplenum fluid temperature for the blind calculations.
,.-,..
800 I~'---'700
<DI...
=-+-0 600I...OJQ.
E<D
500
-+-c0
0 4000U
3000 10
21
. ::".:::-::" ," ,,-.. :.
... . '. '~: : .>:
GRS (DRU) fO0 JA T (THY)0 STUD (RS)6 CEA 500
TE-PC-0018
400 o"-Q)0..EQ)
coooU
300
100
200
20 30 40 50Time (s)
Figure 9. Comparison of measured and calculated intactlocp cold leg temperature for the blind calculations.
600
..--...~ 550 _
root0.. 450EQ)
...... 400C0
00 350U
3000 10
22. .;. - .
700 800JAR
0 CERL .....-.-.....-.-EIR ~~ 0
'--' /:;. ENEL '--'
Q) 600 TE-PC-0028 to Q)~ !...:J :J.. '-'
L...:J0 0~ ~Q) Q)
~ 500 f 0...
400 EQ).... -+-
c c0 0400 -0 00 200 0U U
3000 10 20 30 40 50
Time (s)
10 20 30 4.0 50Time (s)
Comparison of measured and calculated intactloop hot leg temperature for the blind calculations.
700
.....-.-~'--'
Q) 600~:J..0~Q)
Cl.. 500EQ)
-+-c0 40000u
3000
Figure 10.
23
oo6.
GRS (DRU)JAT (THY)STUD (R5)CEATE-PC-0028
800
200
Q)!...:J
o!...
Q)0...EQ)
-+-coooU
,j ....• ::
, , . :"":;, ".. ,
'.' i:...
7001'00JAR
I,......... 0 CERL .....-...Y: 0 EIR ~
0.........., ..........,6 ENEL J
CD 600 ;- TE-P139-020
1600 CD
l- I...
~ ~-+-a --- al- I...
CD CD0.. 500 0..
E 400 ECD CD
-+- .....c ca 400
a0 00 l 0u
Iu
3000 10 20 30 40 50 ()Time (s) :.~:. ' :.;~,
...;;:..... ':.,
.....-...Y:..........,
roo 1~ 500 LECD
-+-ca 40000U
300a
Figure 11.
1800
!- GRS (DRU)16 JAT (THY) .....-...
STUD (R5) ~0
1_6.
CEA~
..........,
TE-P139-020 600 CDI-
::l~.~
-._- aI...
CD0..r
400 cCD
-+-ca0
200 0U
10 20 30 40 50Time (s)
Comparison of measured and calculated pressurizertemperature for the blind calculations.
24....... "
10 20Time
30(s)
40 50
Q)
L:J
oL
Q.J0...EQ)
+-CoooU
+-CoooU
Q)
L:J
oL
Q)0...EQ)
+-
510
GRS (DRU)J A T (THY)STUD (~5)CEATE-SG-003
oo6.
I II-r 540II!I
I-LS30I
I1520
~ _ - _~. '\l:'X"~/ ~ ~/ cr---.;~ .ffi~ '.-T v~ '_.- . ./.~--'
-- 545
--c0
0 5400U
5350
Figure 12.
560 I
10 20 30 40 50Time (s)
Comparison of measured and calculated stda!nger.drator secondary temperature fc: the blindcalculations.
Q)
L
:J
~ 550 -:[ /~'&Q.J rh'0..EQ)
,..........~'--" 555
25.. :. ::::> ..
4.4 Fluid Density
The comparison between the calculated average volume density and themeasured density in the intact loop cold leg showed significant differencesas presented in Figure 13. Five calculations (CERL, EIR, ENEL, JAR, JAT)resulted in an initial voiding of the cold leg, followed by a completerefill. This refill time ranged from CERL's 16 s to JAT's 31 s. Thisrefill was considerably different from the oscillations seen in the data.STUD calculated a single slug of liquid from 13 s, to 17 s, then voidedcompletely. The remaining submittals simply voided the cold leg. Theproblem could be connected to the average density calculation and thedifficulty the codes have calculating the effects of subcooled ECCinjection.
There was better agreement between the average intact loop hot legdensities and the data taken in L2-5 as shown in Figure 14. By 30 s, allparticipants calculated a voided hot leg. JAT and ENEL calculatedsignificantly higher density between 5 and 20 s than other submittals.
In the broken loop, both cold leg and hot leg shown in Figure 15and 16 respectively, there was again considerable difference in thecomparisons with the measured density and with the participantscalculations themselves. All of blind calculations, with the exception ofCERL, predicted a slower voiding in both legs during the first 10 s. Inthe hot leg, all participants's submittals showed a voided pipe after20 s. In the cold leg, slug flow, seen in the data, was evident in theENEL and CERL calculations. STUD, JAT, and EIR calculated major refills ofthe cold leg pipe starting at times ranging from 16 s (STUD) to 35 s(EIR). Both STUD's and JAT's analyses showed the cold leg pipe emptyingagain between 35 sand 42 s. EIR's calculation was terminated before thecold leg emptied.
4.5 Mass Flow
A comparison of the calculated core inlet flow, presented i n ;\
flow signature of a major,,~,.
Figure 17, shows the characteristic reversed corecold 1 eg break. All participants, except JAT, calculated approximately the
26
.... ": "'. '::'.> .. :..:..... :.:'.',
2000
JAR0 CERL0 EIR 100 ....-.-~ 1500.., 6. ENEL
l0
E -DE-PC-001B'+-
'-.. '-..Ol E~ ..0
'--" 1000 ' " Cl ,~ '",""">- ,I ~ " II '--"
! I, /1 ' , 50i! " , \ 1\ >0-
VJ I. 1\ I, IIJ ' ,
c i I '\ " , I 1\Q)
'\ I: Ii 1\ I , i i!i (fJ
500 I, c'"'0 I i 'I ' ' . \ l' I II' \ ! ii\ 1\ I (1)
to I \ ' ,'I u"'0 \ \ ' I ~,i ~~,! \ I \ I o I \ 0 ' \ I::l I o 0 10 01 u
'-./".",/ \1 \.'\l \ I ,} \0 \ / ::lu.. 0 0u..
-5000 10 20 30 ~O 50
Time (s)
(fJ
c(1)
u
50
GRS (DRU)JA T (THY)STUD (R5)CEADE-PC-0018
I I~ " 1\'\ /\ IiI. 1 II I, I \,\ "ii, ! 0\ il. II; \ ; i!'1 ! I,, \ 1'\ ,f If 'It \ ! 'IiI, I \ I >\ I
I / ; 1 Yo'I ~ I i \ ! \ I 0 I " ,\ II
' 0 I,' I\/ \I\/~ \/ \' ,\' 0
500
o
2000 11500 I
1000 rVJCQ)
'"'0
.......
-500o
Figure 13.
10
Compa ri son 0 floop cold leg
20 30 40Time (s)
measured and calculated intactdensity for the blind calculations.
50
27: - ....... . .
" ...... :::>.: . .: ,~.
800JAR
0 CEKL0 EIR 40 -----.-----.
r<1 6 ENELr<1
E-+-
DE-PC-0028'+-
'-... '-...en 30 E.Y ..0"--"
."--"
>--- 20 >-(I)
-+-
C If)
Q) Cu I10 (1)
U
U
:)
U
--~ -, - -- C :)
u.. -'" - "'.-...;-~ ./
l.&-
-10
0 10 20 .30 .10 50 C:hTime (s)"v.W'
800 rGRS (DRU)
I l0 JAT (THY)0 STUD (RS) 40
-----. 600 1-----.
r<1 6 CEA r<1
c0--+-
c DE-PC-0028'+-
'-... '-...en 30 E.Y ..0"--" 400>-
"--"
-- 20 >-(I)
-+-
c If)
Q) 200 cu 10 (1)
uu
:) IU
'\
-,J- , ,
LO' ~"'" ,---,---, 0 :)
u.. -" v bU./. t:=<? ~~. ,~ /1 u..
-10!
a 10 20 30 40 50Time (5) --
Figure 14. Compa ri son 0 f measured and calculated in t act [,
loop ho t leg dens it y for the b Ii nd co I cui ati ons.,,-'--
28
..': ::.. '" .'
',- -:" . ":,' .. '
.:::.::.' .. '
(/)
CQ)
""'0
""'0
::J
~
..............
E..0
5040
craooJARCERLEIRENEL •OE-BL-OO,B
3020 Time (5)10
800
(/)
c(J)
-a
60
~ -----..to-
l40......
..............j E
~
Ll
"--"
>-
120 (/)cQ)
""'0
""'0 ,.-::J
~
504030
20 (s) d brokenTime Iculated an
d co Iculations.e
'" d caf measur the bino .ty forleg densl
10
. onComparl S
loop cold
>-
1000
Figure 15.
IIICQ)
-a-a.-:J
L...
29. . ... :... '~~'. . .. , " ..
. ,"
. '''.: =:,';; ", .
",' : ...:.:: . .. .."..
1000 60JAR
0 CERL...--.. 0 EIR ..........r0 D. ENEL t'i
r4-
C DE-BL-002A '+-
~ 40 ~lJ) E~ .Q'--'"
-"--"
>- >-(/)
4-
c ~20 (/)
lD CV <l)
v 200 -0
::J-0
u....::J
0 0 u....
-2000 10 20 30 40 50 G'Time (s) ~q~~,':.~j!~
~.~\:i;'"
1000 60
(/)
c<l)
v
~ 40
~ 20
II
';fJ 0
GRS (DRU)JAT (THY)STUD (RS)CEADE-BL-002A
ooL
o
500
-20
-500o 10 20 30 40
Time (s)Figure 16. Comparison of measured and calculated broken
loop hot leg density for the blind calculations.
50
30
.. "' ",'
" ".. :'" >
400
200"........
(/)
-.........0 E..0
"---'-200
~0
.....-400 en
(/)
0
-600 2
-800
10-400 o 5
Time (s)Figure 17. Comparison of calculated core inlet flows
for the bli'1d calculations.
200GRS (DRU)
0 JAT (THY)0 STUD (RS)I'::. CEA
"........en
-......... 0O"J~"---'
~0
.....enen -20002
31
"
"
. >,:: ..:.. J" .'
-'.""
same peak reverse flowrate. JATls calculated peak flow was about 1/3 ofthat seen by the other calculations. By 10 s all calculated flows hadessentially stopped.
For the calculation of a large pipe rupture, the break flow modelswere critical. As discussed in Section 3, virtually all participants useddifferent models or multipliers for their break flow studies. Figure 18and 19 present the results of these studies in comparison with data. Ingeneral the agreement between calculations and data is quite good. Peakcold leg flows calculated by CERL and CEA exceeded data significantly,while JAT underpredicted the cold leg flow substantially. In the hot legonly EIR underpredicted the break flow while most of the participants,including JAT, overpredicted the hot leg break flow. The discrepancies inbreak flow are better seen in Figure 20 which shows the integrated masslost to the system through the breaks. EIRls calculated mass lost came theclosest to matching data. JAT first underpredicted the mass lost duringthe first 9 s, then overpredicted. All other participants overpredictedthe mass lost with STUDls mass lost being some 50% higher than data by 30 s.
Figure 21 shows the calculated mass inventory in the reactor vessel.While discrepancies in the initial mass make exact comparisons difficult, aqualitative review showed some explanable differences as well. EIR did notexperience a refill in inventory, while STUD calculated an insurge between15 sand 23 s, which emptied out by 30 s. GRS, JAT and JAR calculatedrefills starting between 25 sand 40 s.
Emergency core coolant injection is shown in Figures 22 and 23. Allparticipants underpredictd the initial HPI peak flow. High pressureinjection flow was overpredicted by STUD and JAT after the initial peakflow. Low pressure injection was calculated reasonably well by allparticipants, except JAR, which showed high flow as well as what appears tobe some possible modeling problems.
4.6 Pump Speed
Pump coastdown, simulating the loss of offsite power in L2-5, iscompared with data in Figure 24. Most participants followed the coastdown
32
',.,":...........
::." .
2000
JAR 40000 CERL0 EIR
1500 6 ENEL ~~ FR-8L-OOl 3000 VJ
VJ '-...'-... Ern~ 1000 ...Cl
........... 2000 ...........~ ~0
-l 10000
'+- 500 '+-
VJVJ VJ0 r-, VJ
L 0L
0 0
-500o
2000
1500~
VJ'-...
1000irn~...........
~0
'+-500
VJVJ0L
0
5Time (s)
-- GRS (DRU)0 JAT (THY)0 STUD (RS)6 CEA
-- FR-BL-OOl
.-,
10
-1000
4000
3000
2000
1000
o
~VJ
'-...E
...Cl
~o
VJVJoL
-500o
Figure 18.
5 10Time (s)
Comparison of measured and calculated brokenloop cold leg break mass flow rate for the blindca Icu Ia ti ons.
33
-1000
. : =' ::; '.~~.'. . •.. : ; .: ".,... ' ::,':j':,... ,
":., ..... ", ",,:. : .
. ':."
2000
i-- JAR 40000 CERL0 EIR
1500 6. ENEL ".......
"....... FR-BL-002 3000 (/)
Vl "-"- E
CJ).:::t.
1000 i ..0
'--' 2000 '--'
~ ~a II
500 ]
0- 1000 -Vl (/)
Vl0
(/)
~0~
a 0
-500-1000
0 5 10
Time (5):~."
,,:.;W~
2000
GRS (DRU) 40000 JAT (THY)
15000 STUD (R5)6. CEA ".......
"....... - FR-BL-002 3000 (j)
Vl
1000 J "-"- ECJ)~ ...0
'--' 2000 '--/
~ ~a a- 500 l 1000 -Vl ~(j)
Vl
0 .""" ~ ~ ~ ~ Vl
~~ - c- o
~ ~ " ~ :2~DE 0
-500I -1000
0 5 10Time (5)
Figure 19. Compari son of measur ed and calculated broken.-
loop hot leg break mass flow rate for the b Ii nd \
calculations.~,
34
........... ..' ..... ':: .
8000
6000~15000
;--...Ei_C?-Q9---- 10000 ;--...
0'14000 t 1_-
tsooo
E.::J:. 10 JAR -0......., CERL '---'Vl 10 EIRVl Vl
0 2000 6. ENEL Vl
~ FR-BL 0~
0 10
I-2000
a 10 20r () 30 40 501me S
8000
5000
VlIf)
o~
15000
;--...
E___ ---- -0
10000
-- GRS (DRU)0 JAT (THY)0 STUD (RS)6. CEA
-- FR-8L
o10 20 30 40 50
Time (s)Figure 20. Comparison of measured and calculated integrated
break flow for the blind calculations.
6000
;--...0'1
.::J:........,4000
VlVl0~
2000
35
.j: '. ".... ~:j
~.":
"; ...":.. ;' ..
3000
2000
10 20 30Time (5)
I~
40
JAREIR
50
6000
4000
-----E..0
'--'"2000
VJVJ0L
0
-2000
5000
2000
10000
mass
e ! --e- ~----]040 50
GRS (DRU)o JAT (THY)o STUD (R5)
G
10 20 30Time (s)
Comparison of calculated reactor vesselinventory for the blind calculations.
_m_~
a J ----==-'o
F igu r e 21.
1000
4000
---------- \. E01 3000.::i. ..0"'-" '--"
VJVJ CIl
0 2000CIl
~ 04000 L
36. .~.. ':,': ::., ',,"
.' "" :,.:-::,' . ..' " ..
. . ..'~ .;: .:,':: .;~:..' .. .
4020 .30Time (s)
10o
o
2 I1- l4r, JAR
i \ 0 CERL\ 0 EIR
I 6. ENEL r---.,..-" 1.5 I \ FT-P128-i04
r3VJl/l
\ """-'-.... I E0'> \~ I ..0'--'" \I '--'"~
I \ 12~0
\ 0...- I -l/lVJU)
0 VJ::z tJ0.5 :L
2 IL 4
1.5r---.r---.
3 VJl/l J"""-"""- I0'> J E~
'i.Ll'--'"
2 '--'"~$0
'+-GRS (DRU) 0
0.5 J-JAT (THY) f.- '+-
l/l
IVJSTUD (R5) l/l0
VlCEA I:L 0FT-P128-104 :L0
'-' 0
-0.5o 10 20 30 40
Time (s)Figure 22. Comparison of measured and calculated HPIS
flow for the blind calculations.
-1
50
37
'.' ..... .-.. , ..- .' ... "" ..::::. :..
',.;
.::: . ..=; ......
:: .. :- .::; ". .' ..... :: ':~',;. - ~'. ;:.':.: ...:. .:~,:;. ..
. .
.:;j}o
504020 30
Time (5)10
oo
40
JAR0 EIR ~80
FT -P12 0 -085
30 J -..-.. fI"JUJ '-...'-...en 60 E
..Y ..0"--"
I "--"~
20 { ~0'+- 40 0
--UJ iUJ I fI"J0 fI"J
~ 10 L 0L
15
GRS (DRU)0 JAT (THY)0 STUD (R5)£::, CEA
,...---. FT -P120-085UJ'-... 10en..Y"--"
~0
'+-
UJ /.-
UJ 50
~
oo 10 20 30 <1.0
Time (s)Figure 23. Comparison of measured and calculated L.P!S
flow for the blind calculations.
30
25 ,...---.I/)
'-...E
20 ..0
"--"
~15 0
--I/)
10 I/)
0L
5
050
<.\..."- .
38
2000 2000JAR
I0 CERL0 EIR I15006. ENEL r 1500....--.
E RPE-PC-OOlIQ. I~
'--" I 100C-0 TOJOJ
,_./~......"",/a.Vl /'-
500 500a. ,~
C:J
Q..
0 0
-500,I
-5000 10 20 30 40 50
Time (5)
5000 5000
30CO
o
I--: 4000
I2000
1000
GRS (DRU)JA T (THY)STUD (R5)CEARPE-PC-OOl
oo6.
~I 'I \I
)~1000
o
4000
3000
2000-0
OJCDa.Vl
a.C:J
Q..
-1000o
Figure 24.
10
Comparison ofcoo I an t pump
20 30 40Time (5)
measured and calculated reactorspeed for the blind calculations.
-100050
39
:::;";.; "..: : .~."~.. .
..,: ",
.~..:: . .: :~..
well, taking the various initial speeds into account. EIR calculated amuch higher speed for the first 20 s, then degraded to an abrupt shut offat 34 s. Only the two Japanese submittals did not calculate a pump speedturnaround. STUD calculated a tremendous increase in pump speed, to nearly400% of initial speed between 16 sand 31 s. This peak is similar to thepump speed increase experienced in L2-5 between 25 and 59 s, but the datanever exceeded the pump's initial speed.
4.7 Rod Temperature
The comparison of cladding temperatures with data is difficult due tothe variety of modeling techniques used by the participants to model theheat slabs in the core. With this in mind, Figures 25 and 26 present thecomparisons with data for the 0.76 m (30 in.) elevation and 0.99 m (39 in.)elevation. For the first 30 s, GRS comes very close to matching thetemperature profile at the 0.76 m level, with a peak slightly higher thandata. JAR, ENEL, JAT and CEA all underpredict the temperatures but showthe stable high temperature plateau seen in data. CERL overpredicts thetemperature plateau, while STUD reaches the same peak as CERL but shows adefinite quench. The quench seen in the STUD RELAP5 calculation starts atthe same time as the increases in loop densities and the pump speed.
At the 0.99 m level, the data from L2-5 is characterized by twoquenches at 15 sand 47 s. None of the participants, except EIR,calculated these quenches at the presented elevations. Initial increasesin temperature were well predicted by all except EIR, which used an averagecore model for this elevation. Only JAR overpredicted the temperatureprior to the 15 s data quench.
4.8 Summary
In summary, the eight blind calculations performed satisfactorily whencalculating hydraulic behavior except when modeling problems, such as EIR'spressurizer, STUD's pump and JAR's LPIS, interfered. The predictedpressure-temperature histories were generally lower than data. Subcoolingand superheat within the primary were not well predicted. Except in theintact loop cold leg, densities were adequately predicted. In the cold
40
\''''--' ....
.... ,: '"
.:' ',',': ::.',. "';"
',::' '::.", .. :....
. .::< .. '
'..~:: ,:~ ;: ': " ~..,
1200 II
----- l ~1500~
~ l.L.........., 0
'--"
1000 r _ . .,..-.--. -' ....... .......... _-"
Q)........ ~_.
, ./ Q)
~ I....
::::l r ::::l
{) 1 ) ./.. 0
I.- i'(.. "----- I.-Q) I"
\...------- Q)
0..800 t~j JAR J-1000 0-
r- E!:
I ~-CERL I
Q) ENEL Q)
Ii TE-SH07-026(J) (J)
c
t500
c...:..-0 600 -0<J -00 0
U U
400 I0 10 20 30 40 50
Time (s)
(J)c
GRS (DRU)-0
0 JA T (THY) -0
0 STUD (RS) 500 0
6- CEA UTE-SH07-026
{)I.-Q)0..EQ)
-+-
(J)c
<J 600<J{)
U
_.-'~- .- -- .- ':--- _.-.....-.-.../~1500
,,-.\ -, ~' \- . -='.......
il1000
oI.-Q)0-EQ)
400o 10 20 30 40 50
Time (s)Figure 25. Comparison of measurtld and calculated rod cladding
temperature at the O.76m I3levation for the blindcal cu la ti ons.
41
'": ,.' ....:: .., "
':. ~j' . .• .";" ::;::.: .. .' :" ..;..::. .. ~; ":'.: :.:'.., ,
'::.':;. ;:::> .: "
'..'"
o.1200
IIJAR
0 EIR I ----......... J ~1500 I..L..~
I6. ENEL
0
.......... ..........TE -5HO 7 -041 Q)
Q) 1000~ I I-
::::::l
I /~'"::::::l
......0 0I- e;-- ~. I-
Q)Q)
0.. ,- .c.. . 1000 0..r- 800 - / \ Ec ~. iQ)
Q)
0) ,hi, / - .-' - . --- - ,-' '-..... '\ "'~ .... 0)/' - ,
C ./ CI
-0 600 -0-0
~
\ -00 500 0
'-.J U UU
4000 10 20 30 40 50
Time (s)
40
I
GRS (ORU)o JAT (THY)6. CEA
TE-5H07-041
\"..,- .. '
l'500 ----I
}o-
I..........
lQ)
L::::::l
0LQ)
1000 0..
EQ)
0)C
-0l:J
500 0
u
'--
50
rod c I add ingthe blind
---./
10 20 30Time (s)
Compa ri son 0 f measur ed and ca I cu 1a Tedtemperature at the .99m elevation forco Icu Ia ti ons.
1200 I
.........~~..........
~Q) 1000~
I::::::l
0L
800 tQ)0-r-CQ)
......0)C
-0 600-00
U
400 I0
F igu r e 26.
42
" .. ";" :.
leg, however, the predictions ranged from liquid full to vapor full withoutthe slug flow behavior seen in the data~ Break flow and mass lost to theprimary was overpredicted by all participants, except EIR. Calculations ofECC injection and pump speed were adequate except for the above mentionedmodeling problems. Rod temperature profiles were very model dependant.Heatup rates were calculated well, while quenches of the clad were notpredicted.
43
....... : .... :" " . .' .: ~'
5. SUMMARY OF OPEN RESULTS
The calculations submitted by LANL, DCMN, VTT and the second EIRsubmittal were designated open calculations because the models used inthese analyses were not submitted prior to the L2-5 experiment. Theseparticipants were alowed to make code or model changes to improve theirpredictions. Comparisons of experiment L2-5 data with the code predictionsare provided in the following sections.
5.1 Sequence of Events
The measured and calculated sequence of events for the opencalculation were included in Table 3. For the most part all opensubmittals calculated the experiment's sequence of events well. EIR andVTT scrammed the reactor earlier than the 0.24 s experiment scram. VTTpredicted an early deviation from saturation temperatures while EIRpredicted a later one. LANL tripped the pumps early at 0.24 s rather than0.94 s. The participants calculated pressurizer voiding between 8 s (EIR)and 28 s (LANL). ECC initiation was well calculated. The time of peakclad temperatures, however, ranged from 5.2 s (VTT) to 50 s (LANL).
5.2 Pressure
The calculated pressure in the pressurizer, intact loop cold leg,broken loop hot leg, broken loop cold leg, and upper plenum are comparedwith data in Figures 27 to 31, respectively. EIR and VTT underpredictedthe pressure in the pressurizer, while LANL and DCMN calculated the dropextremely well for the first 15 s, then overcalculated the pressure from15 s to 40 s. In the loops and upper plenum, the same basic pattern wasseen with EIR and VTT generally under the data and LANL and DCMN generallyover. But all participants calculated the loop pressure history well.
Figure 32 shows tQe comparison between calculated secondary pressureand data. The ErR calculation showed the best comparison with data,following the pressure history quite well. The LANL calculation showed aslow oscillation in secondary pressure, while the VTT depressurizedsubstantially.
44
C'-r," ',' "..f. .
./
(,.....~
- : .:;~.~:.".:; ..
-- ---,----------- I
2500 ~0
If)
n..2008. '----"
Q)
....:JIf)
1500 If)
Q)
l-n..
~ 1000 Q)
I (J)
~0I-
~500Q)
>I «I
EJ ,~ JLr~O
50
--,-----------,----------~
1-- EIR \I 0 LA NL (TRAC) ,I (J DCMN! 6 VTT (RS)1- - PE-PC-004
20 30 40Time (5)
mecsured end c:Jlculuted pressurizert he:::pen co \t:'J! 0 ti ors.
10
Comparison ofpressure for
o
Figure 27.
20000 ---
Q)
I-::;If)If)
Q)l-
n..Q)(J)
oI-Q)
>«
IEIP iLANL (TRAC) i-2500 ~DOliN I 0VTT (R5)' J If)
PC:-PC-OOl n..r 2000'----"
Q)
! l-
I ::;I If)
1-1500 If)
"I Q)
I l-
I n..
~1000 Q)
(J)
j 0l-
I Q)
'-500 >I
«
1010i6I1--
20000 I
jI
15000 r10000~; .\ '
",
i'~::O~ "~-
5000 ~ ----.~~~'Sl.~-~ '--<i"'>F;
1"~.-""-'-
I .....,,">-:-'.~r-.----'! ---~~~'--.
o L . i.- ...!- -=-_,-_~.;""_,..,.;....--,.l... _-----~=8~.-:~' __-.-~-=-.:.-~~~2:0
o 10 20 30 LO 50Time (s)
Figure 28. COnlparisor, of me'JsL.f'ed and cclcuiated int'Jct loopcoiJ leg pressure ror the cpe:l caku:ations.
::;V'lIf)
Q)....n..
Q)
Q)(J)oI-Q)
>4
45
••• '0"- ..'.", .:;. ' .....
loop
<1.0
EIRLANL (TRAC)DCIANVTT (R5)PE-BL-002
oo6.
2010 30Time (s)
Comparison of meosurec and calculated brokanhot leg pressure for the open calculatio'1s.
Figure 29.
15000 r1
Q)
I.-:.JV1V1Q)I.-
0.
Q)0)oI.-Q)
>«
2500 r--.0
(fJ
I n.
roooo "-..-/
Q)
I.-
:.J(fJ
1'500(I":Q)
I.-0.
J
(00'1J0)0I.-Q)
1500 >«
IIIWo
50
EIRLANL URAC)DOANVTT (R5)PE-BL -00:
20000ji
15000j~A--
10000 '.~I~ ..
j~5000~ -~
~ "~~~I ~'~~~7
o ._1 --- -1-_ ~;--=--=;~-:--'""';~=:;O;'. ==c=~__-,_-_-:-=:1_.
o 10 20 30 40Time (5)
Figu,-e 3C. Comparison of measured end calculated broken loe,pcold It9 pressure ior the cpen calcu!aii01s.
Q)
L:.JV1V1illl.-
n.ill0)oLill>«
46
::~::. ...:' :..~. ' .
I1
i~2500 ,..--...
0
~ (j)
i QI '-...../12000I OJI l.-i :Ji (j)
1-1500 (j)
OJ"-0..
r 1000 OJCJl
1 0I.-OJ
I >~ 500 <ti
---.J.'+-'0
50
uppe r plenum
40
EIRLANL (TRAC)VTT (R5)PE-1UP-001A 1
,.......=
1--
I~,_-
20 30Time (5)
measured and calculatedt he open co Icu I:: I;ons.
10
Cor"71pa ri SO'1 0 fpressure for
F igu r e 31.
OJCJlo"-OJ>
<t
OJ
"-:J(j)(j)
OJI.-Q
OJOlo"-OJ>
504020 30Time (5)
of me0sL.red cnd calcu laled s+eamsecord',]I-Y presser" for Ihe open ca!cuiari'.Jns.
10
CQrrl:)ariso~generator
::-igure 32.
6500 I
I I EIR~ I~ LANL (TRAC) ~9GOa i . 6. VTT (R5) --10.. 6GOO r -, PE-SGS-OOl I
: r~::~~<~----,,-----~~v.~--._-~ I~ - ~-. "il ..../B 1 :,~ ---5 - '='~800:J 5:JOO.::... '.:0', ~",._- -..;.-:r- l~ i -.~~ =--... I~ i--~~ i
~ 5000 L "'-.....,~ lI ~~~700
~6004000 ~I ~ ~ ~ ~_______ '
o
47
5.3 Fluid Temperatures
Upper plenum temperatures are compared to data in Figure 33. For thefirst 28 s, the submittals showed the same relation to data as did thepressure histories, with EIR and VTT below data, and LANL and DCMN above.In this period, DCMN's RELAP4/MOD6 calculation followed data extremelywell. At 28 s both the L2-5 data and EIR's calculation began to registersome superheating. Magnitude of this superheat was higher in thecalculation than in the data but the shape and trend of the curve wasnearly identical.
Comparison of lower plenum and intact loop cold leg temperatures,shown in Figures 34 and 35, again show the same relationship as thepressure histories. EIR and VTT were generally lower than data until 28 swhen the cooldown calculated by VTT slowed enough to reverse the trend.LANL's temperatures were higher than data until the 35 to 40 s range whenthe comparison reversed. DCMN's lower plenum temperature comparison wasexcellent.
Hot leg temperatures (Figure 36) again showed some superheating in thedata. As in the upper plenum, only EIR calculated the superheat but atmuch higher levels. Both LANL and VTT calculated a cooldown which followedtheir depressurization histories.
All the open calculations underpredicted the average coolanttemperature in the pressurizer shown in Figure 37. Secondary temperaturescompared in Figure 38 show better results. The VTT calculation's secondarycooldown followed the depressurization previously mentioned inSection 5.2. The remaining two calculations stabilized by 15 sandremained constant, with LANL calculating an average temperature nearlyidentical to data.
5.4 Fluid Densities
The measured density and the calculated average density in the intactloop cold leg is shown in Figure 39. The calculations all showed the coldleg voiding with subsequent slug behavior later in the transient. The time
48
...... ':'.:;
C.,."~.';I,' .~.~ :.,. :,
.. ~" ,:'
c..':..'1'.~"'.:/
',,- ..
o~Q)
0-rCQJ
Q)
(J)
o~Q)
><t
500
700
600
504()
EIRLA NL (TRAC)DC'v1NYTT (R5)TE-1UP-OOl
l-Ie[01_6
_
20 30Time (5)
mecsL.red end c~lculated ~pper.",rnperahJre for the open calculations.
10
Comparison ofplem:m fl'.Iid
IIl!
4.00 ,-o
501)
F i gur 8 33.
coocU
-+- 450-+-c0
0 4('l) -0u i
I
350 l --L_
0 10 20
Figure 34. Compo ~ison ofple'1um fluid
30Time (s)
~easured and calculatedtemper-o'ure 70r ihe open
50
lowercclcu:atia;1s.
QJ
~:J
o~QJ0...
EQJ
QJOlo~QJ>«
49. .- :. ..: .. '.. ::~. .. ...... . ".:', .. ;....
':.... ;.', '::-.;::.':} ....;:.....
OJ
OJC'1o'"-Q)
><t:
o!...OJQ..
EQ)
-+-
~ 4:JOI
I
20 30 40 50Time (5)
me': sur ad end C:J leu I<J t e din t act+"''"flperatur€ for the C'j.',?n c:Jlculctic:ns.
-,-"-- .-.--, ..-------.--.-., ....----------r----- ---.._----,r----------, I.GOOi- EIR I. [j L.ANL ('RAe) :
.:'~ v IT ( R5 ) -'L.:.... iE-PC-QQIB i500
1
10
Cornporisor of100,0 cole:; leg
Figure 35.
600 I
l,..-... ,-"" ~Y:: 550 '-7<"",,'."-../
OJ!...::l 500 -0~q; ic.. 450EQ) J
-+- 400C0
00 350 r-U I
I,,...,300
0
Q)
!...::l
Q)01o'"-Q)
>«
o'"-Q)
0...
EQ)
600
!... 4:)0!
!700,I
_i
I:-500
504-0
EIRLANL (TP..~C)'In (R5)TE-PC-C'C2B
: ,! ........:..
i-'
l-iD
20
..' ... . _...L..... __
30Time (5)
Comparison of meo~ured and c'Jlculc~ec intactloop het leg ta;r,pe"aure. for the .:;pe;, calculut:0Ils.
i4CO 1 __ .. .- --- I
o 10
Figure 36.
650 -I~------c
I
coc 450oU
50.......... .':
-" ,.".". ",' ::" ...... :..
- •.. "'-, ., ...•.. "":.;'11":.".,,
Q)
a>oI-
'l)
><:
o!-.Q)
Q
EQ)
-+-
600
400
llSOOI
--.
EIRLANL C:-RAC)VTT (R5)"'E-P139-:::'20
l-iD16
-- '-
700 ------- ..-T
iI
...--.. I6 --lQ) 600 ~~:G~-' - --
~- ~ --~~! '\'~~'-"o I "C..::::.- --c-~ I ~~~-, ~~Q)' ~~',
0... 500 JL '''-''. . &.-.-_E -,~,--------_ ~Q) 1'- ~ '
i ~~----~_, I
C I ~. ~~o 400 r '~ 'I01,
c3 1 ~200
300 i .-l. -----L- l-- ~ .~
o 10 20 30 40 50Time (s)
Figure 37. C::>rrqarisor of mecsured end c:Jlculated pressurizertemoerctlJr-e for the op",n c(]!cularions.
())I-:J
oI-())
0...
E())
Q)U1oI-
m>
-<t
402010 .30Time (s)
Compo ri son c f measu r ed and C;J I GU I at ed steamgener'(J~cr secor-dary terllperature for the openco I cu 1 a ti ons.
c0
53000u
5:20 ,
0
Figure 38.
560 I II, EIR ~I I' 540...--..l 0 L.ANL (TRAC)
2:S I ! 6 VTT (R5) II TE-SG-003 I
Q) 550 f- l
~ V~~~~~-__---_.-._--________! ~~o~ ~---n___ 'G<._. :-l _ I.'JL~ t;40f.j /,---:~----=i:f~~~r: -8 3~y~--:::~' --::::t:3=-4E ..... .../ -.............. I
n, ~. I:. /J-~ I-+- '--~ r500
~J
'*I'--- ---'- ~ .. ~ J 480
50
51
.. ::-"'.
the slug flow began varied from 16 s (VTT) to 39 s (LANL). Theoscillations calculated by VTT were much less severe than those seen in theexperiment and those calculated by other open participants.
Figure 40 compares the calculated average density in the intact loophot leg with the density seen in the data. All calculations showed similarresults with the hot legs simply voiding during the transient. Theagreement with data was good for all the calculations.
The comparisons of calculated and measured densities in the brokenloop are shown in Figures 41 and 42. All open calculations showed a slowervoiding in the cold leg than data for the first 20 s. Both EIR and LANL~alculated major slug flow through the cold leg at different times in thetransient, but this phenomenon was not observed in the data. In the brokenloop hot leg, the calculations showed a faster voiding than was observed inthe test for the first 20 s. After this point, all submittals remainedvoided with the exception of the VTT calculation which experienced slugflow after 44 s.
5.5 Mass Flow
A comparison of calculated core inlet flows is shown in Figure 43.The reverse flow peak, characteristic of a cold leg rupture, was calculatedto be much more severe by EIR than either LANL or VTT. However, by 10 s,all calculated flow had essentially stagnated.
One of the most critical comparisons was that of calculated break flowwith data and is shown in Figures 44 and 45. These results reflected thevarious break flow models used by the participants. After 3 s, all of theparticipants overpredicted cold leg break flow. LANL underpredicted thepeak flow in the first 0.5 s, while DCMN and EIR overpredicted the peak by50 to 70%. VTT nearly matched the initial peak, earlier than data, thenunderpredicts the flow until 3 s. In the hot leg, VTT overpredicted theflow significantly, as did DCMN. EIR underpredicted the flow, while LANLfollowed the hot leg flow history reasonably well. However, the bottom
52
. :- :.~.:: ,'.: :'..... ,<: . ': ..... ::
Q)
O'lo!o-
Q)
><{
(/)
cQ)
u
~100-I
1! ~50i I; i, 1
!1:
50
'I', ~~.',- ,';\; , i'/ ' ',':t' ,1', ',t, ': '....;\.1.',
\ II' ,'r;' J J', _ A ,/ 'j '1(' "L:.,.' ", I\, I,;i, i 'Iw
iJIJ ~'~Q
II,,
\S~" I :~\, i! 1_ : ",.' \
EIRLANL (TRAC)DCMNVTT (R5)DE-PC-OOIB
20 30Time (5)
nldGSUrdC and caiculatdd intactdensity for the open calc:j'ations,
- ----'.- ------_.- !------------ --:-----------,------~I
II
10
Con,pa ri son 'J floep celd leg
I
:"E:L.i
50'J L
100')
Figure 39.
-500 :o
>---+-
VJCQ)
U
(f)
cQ)
---0
Q)
1J>oL
1)
><t
20
30
II
l 40
50
EIRLANL (TRAC)DelwiNVTT (RS)DE-PC-002B
2810 30Ti:",e (s)
Compari:son of l'l~asured and calculated intactioop hot 18g Jc-r,:;ity for [he open ca!cuIJtions,
rigure 40,
(/)
!::Q)
---0
::::J
Lo...
53'. '",: ....... ;..
. ,::.,:.
c..~.,.."'..,:'" \" ...., ... " ,,::..~.J 1
!/lC<1JU
<1JenaL
Q)
>-20 «
5040
-- EIR0 LANL (TRAC)0 DCMN6- VTT (RS)
-- DE-BL-0018I
20 30Time (s)
Ineasured and calculated brokendensity .or the open calculations,
10
Carr,pa ri son a floop co I d leg
Figure 41.
I1I
-500 Io
Q)
enoL
Q)
>«
enCQ)
U
50402010 .30Time (5)
CGmpa~ison of measured and calculated brokenloop hot Ie:; density for the open calculations.
Figure 42.
1000 ~
801]1
_, ,----E-I-R------.. r': 60
~ 0 LANL (TRAC)DOAN ,
I \\'\
,~\400~\,/ . j !l'0o200 ';~ '"t,.. r jJ.
"X~ ) /1~,~_. '.". 5--- I~3 '-.. --...~~, '::.:.-~-.~---' .!
-20: . ~ "-----'-_._~ __ (_%J__,._. _,?__jJ~._.\_bJ_' _-_"_O_'~'_' =_;~_'_'._'.T ro
(f)
cQ)uU
:::::l
lL..
fl"-- .. '
54
, ,' ',' ': ..... : ""':,'..:::::' .:: '.:
~I ." •••.•' ..... : ..
:3o
V1V1a2
dTime (s)
Figure 43. Comparison of colculcted -:o,e inle. flows forthe open ::::alculatiol'"'s.
iI
lOCOI-'
-------V1
...........
500 E-0
'---"
:30
..tt (J
V1V1CJ:2
-500
10
1000
2000
1500 ,..--.,V1
...........r
100e c..0
'---"
500 "$0
'+-
0 V1!IJaL
-500
10(5)
5Time
EIR
I, CJ LANL (TRAC)C DC'AN
I 6 VTT (R5) ~;:~ 1- ° FR-BL -001 !500~~~~} ~r
Ij ~~_~~ I
II \o::"~~.:>=-;::,~~-= ",. 0- ~ cro ~ i . -- ----:..~~-~ _---e-,-c--:':'=:::..~
I lI I
-500 ~ ~ . ~ -1000
o
3o
V1V1o:2
Figure 44. Cc.mpcriscn of nreasured and cclcu'ated brooKenloop ::::old le£ b,eak rr,QSS flc,,.,, ra!e f,):o Ine opencalcu:alions.
55
. .::- .... ; ..... . ..... : .,; . ,. . :" ...:
C/lC/lo~
Figure 45.
10\0\61--
EIRLANL (TRAC)DCMNYTT (R5)FR-BL-002
\
l- 600!
i,
J4CO
2::10 3=o
C/lVJo2:
;-r;,......It. .,."{"<... ..
4000
BODO r
\-j
6000 \
VJC/lo:L
I
I115000
~--c--r_r--~S- I~.-:=-~~ ~--r-i3-i---
/~ r-r---B-~=--:' . - ~-' - - - . - - -' -~ 10000
0::::;;~J¥~C~~ 19 ~r~~(TR'~~)\II
/«:>~J \ 6. Y TT (R5) ~ 5000
2000 \r ,/'vr/ - - FR-BL -1\::f/r- ,I
1t1t/ \o ~ -\-0I
LIi
-2000 ~-- \o 10 20 30 AO 50Time (s)
Fi';:jure 46. Com:)arison of measul-ed end calculated irde-;r<J+edbreak f! ow f G r t he open CCl; ct.. I :::ti ons.
56
-----rC.D
VJC/lo::::
;'.: :''.": ..... : .' .:' ..... ,-:.
line, mass lost from the system in Figure 46, showed that EIR came closest tocorrectly calculating the total mass lost while LANL, DCMN, and VTToverpredicted the event.
A comparison of calculated reactor vessel mass inventories is shown inFigure 47. EIR's initial mass inventory, was significantly lower than LANL orVTT, and all calculations showed differences in final mass inventories.Neither EIR or VTT showed an inventory turnaround or refill while the LANLTRAC calculation began to increase at 20 s.
Emergency core coolant flows are compared to data in Figures 48 and 49.EIR calculated an earlier HPI initiation than the other participants, but thesignificant difference was LANL's flow rate, approximately two times higherthan the data or the other calculations. This high flow was probably a factorin the fast turnaround of LANL's vessel inventory previously mentioned. LPIflow comparisons showed EIR again preceding all calculations, as well as data.
5.6 Pump Speed
Measured and calculated pump speed is presented in Figure 50. Apart fromthe initial value discrepancy, there were no major problems with any of thesubmitta 1 s.
5.7 Rod Temperatures
Rod cladding temperatures are shown in Figures 51 and 52, at 0.76 m(30 in.) and 0.99 m (39 in.) respectively. As with the blind calculations,the significance of these curves was questionable due to the various modelingapproaches to core cladding heat slabs. At the 0.76 m level, VTT's peaktemperature at 5.2 s was close to the peak reached in the actual test but thecladding cooled off significantly from that point. Neither EIR or LANLreached the data peak, although the relatively stable high temperature historyseen by LANL is more characteristic of data. At the 0.99 m elevation, datashowed two major quenches, at 15 sand 46 s. VTT's calculation showed aearlier downturn from 5 to 10 s, then stayed relatively low. LANL, EIR, andDCMN did not display the characteristic quench behavior at all.
57
,. ;'.'" :', ," .. : ". ,'. . . .. ' ':, ':::."; " \"
VlfJ)CL
E.0
4000
Ccmp .:J"i soninventory
500
Fi']ure 47.
2500 ,--------------r--------------------I ,-----------, ij 1-- [I R ~5000
,\ 'I' C LAN L (iRAe) !'..... I 6. VTT (R5)
2000 \-4l~\\i\h
l':;n,] L\--J _ : \ \
i \\ ~3000'I \ ~ ,)
10["'):\ " '\' i-''\ \ ' /~' Jffi./ f- 20001 tSi" 6, ......,...--/--8\,- 2' I
\ ~---", r:;-././<::.J J\ '. 'C"- _ /"C.J
............ l~"'~'tl..\ ~...-'--. '-'-s, ---2 r 1000
~'~~~~---1_.r i
o ~------~-----~------~-----~-----~I 0o 10 20 30 40 50
Time (5)cf cCliculcted reactor vessel massff)r the open ca!::ulations.
VlVloL
3
............c2 ...0
...........
VlVl0L
0
5020 30 40Time (5)
measured and calculated HP!5 flOW
(;oicu!otions,
10
Compoii son 0 ffor t he open
2 I
I1.5 f-
I
I
0,5
~
I .1I
:\'r~~.--'----1~~11: \ ~
(I' ---------,
- \ 1-- EIP
I. , ,~LM1L C-:-RAC) I'
,; \ &, : ~ V T T (R 5 )1,1 \'-\ 1- - FT-P128-~04 tI) " I
f' ~. 1o I
-0,5 J~,---- '-----_'--'- _L __ ,~--_c------,L,o
F i gur- e 48,
~o
VlVloL
~.....--- ..
58...::i....:
....... ,.:.:
(fJ(fJ
Ci:2
-10
30
-..j
~ 20i
EIRo LA ~~L ('RAe)6 VTT (RS)
FT-P120-085
28 30 40 50Time (s)
meosL. r- ed Gnd C:::JI cu I at ed !..P, S flow(;(] I::::u I a ti (Ins.
10
C':mlparison offor t he open
10
i I~5 { I ti~' -- -'r- 10
i U01S- n<-.LS6 ~6,1_.~ TO
I Ij I
-5 ~I ~_ _..- ._-l -----L ---'~
o
Figure 49.
3o
(fJ(fJ
o:2
2000 --------------------------------- 2000
............10GO c
...Q
(fJ
500(fJ
02
G
-500
T 1500!
5040
EIRLANL (TRAC)DC\1NVTT (RS)RPE-PC-001
10Ie:6I;--
30(s)Gnd c:::Jlculated reactorthe open calcuiatic.ns.
20Time
meCSL; redspeed for
10
Comparison ofcoo Ian t pump
Figure 50.
uQ)
Q)0...Vl
59
. :. :.~.'
. ,'. '.~:>.:~:",
14GO , c _
, I
1200-
--------1
Qo6
i--I
---,------------~ 2000
DCMN IILANL (,RAe) iVTT (R5) iTE-5H07-026 I ~
1500
'IJ'IJo:2
50402010 30Time (s)
Compariso;l of merJsurl3d and calculated rod claddingter1p",rature at the O.76rr "I.;>vafion for 'he openca I cu I a ti o~s.
400o
Figure 51.
1000
enc
oL
(1)
Q..,--CCD
u
(/1
'IJo=:
1000
i
I!~ 1500I
J
50
the openfor
40
EIRLANL (,RAe)DCMNVTT (R5)TE-5HO'-041
oI (,
161-.
2010 30Time (5)
COnl;Ja ri sor 0 f meaSLr r ed and co I cu I (I t ed rodcladding temper ..Jlure at the .39m eler/otiol'co I cu Ia ti ons.
i-D~I~&500
IJ
~--------~-------_._---------------~------400o
Figure
1200
o(1)
Q..,--Cill
CDL::J
0'>C
vvou
60..: . :~~.:~..: .~;:.': ." ..' : :'.
-"
...... .,. ~"'."" ...... :: .:;. ':~
".: :'
, .. ," .
5.8 Summary
In summary, as with the blihd calculations the open submittalsperformed well in calculating the hydraulic responce of the LOFT system.Pressure-temperature histories were somewhat closer to data than themajority of the blind calculations. As before, subcooling and superheataccounted for the main discrepancies. Slug flow behavior in the intactloop cold leg was handled better in the open calculations than the blindsubmittals, however, this slug flow appeared in the broken loop differingfrom data. Break flow was overpredicted by everyone except EIR. ECC flowwas calculated adequately except by LANL. Rod temperatures was again quitemodel dependant and, while heatups were calculated adequately quenches wereless adequately predicted.
61
;: '. :~.," ::."'
. .: .~. ..: .. '., .. . , . " .. " .
6. CONCLUSIONS AND RECOMMENDATIONS
Comparison of the calculated results with L2-5 data have led to thefollowing conclusions.
Hydraulic parameters, such as depressurization ratetemperatures were calculated well by most participants.to experience difficulties when voiding and superheating(Sections 4.2, 4.3, 5.2, 5.3)
and fluidComparisons beganoccurred.
Densities in the hot legs of the facility were calculated correctly,but the densities in the cold leg, which experienced cold ECC flow, wereless well predicted. (Sections 4.4, 5.4)
Break flow was overpredicted by nearly all participants withparticular problems encountered in flow from the broken loop hot leg.(Sections 4.5, 5.5)
Good comparison of clad temperatures with data was hampered by thevariety of core heat slab models used. In general, participants calculatedthe heat up of clad surfaces adequately and predicted the clad quenches1e s s we 1 1. ( S e c t ion s 4. 7, 5. 7)
It is recommended that all participants review the comparisons andprovide comments on their particular calculations. This will provide abetter understanding of the models and codes used for the benefit of allISP-13 participants. These comments may be mailed to the author of thisreport or provided at the meeting, tentatively scheduled for July 1983.
62
. ".:-i . 'r-.
.. :,' '.... . .... .~;:. ,.:' .....•.. .....:.~:..... <: :,': ... :-. ".~
",' ;," ... .
•
•7 . REFERENCES
1. P. D. Bayless and J. M. Divine, Experiment Data Report tor LOFT LargeBreak Loss-at-Coolant Experiment L2-5, NUREG/CR-2826, EGG-2210,August 1982.
2. D. L. Reeder, LOFT System and Test Description (5.5 tt Nuclear Core 1LOCEs), NUREG/CR-0247, TREE-1208, July 1978.
63
. . .: .~.", .... ::. "' '.. "
: ~.:~. .:..... ...
........ .
•
..
APPENDIX APARTICIPANT NODALIZATION DIAGRAMS
64
.. . -', : .~~.:~. . ......... ..... "'. '. """ .. ::' .' .. : ;,' \,. ," -. ".
•I..
Control Volume
lIeat Conducter
Junctiono@
~
Scheme of nodalisalion or LOFT L2-S
b/' ;)1 r~-~::>o r-. 67 Ifci\- @ @@J t @ I@>
I 51 65 ~~~ ~(75) t JW ...(7(\ 64 55 I
r 64 ~7~ 56 t'? H 68}----@ @~ ~@ ~@ ~. 68
r:;y.166 i'-19,W ~~lJS: 66 ~6~' ~~ 2/, "\!31"~' 7 0' 6 ~0"''' ,'-"-;52 ~'46. '1 1.6 '\53 ,,15 \!.J 12~ 63 ,,5,'- ",,,,," @
I " , ' ,,\' ;,\'" ~\S A 1@ t ~ @ CD t t * @ '€ZJ 5 _'
G 2 ~~ ~~ 6 2 ~~ ~ ':\ ~ ~l0)\ L-,~~8 5 ",,\ \~ 53 I. 5 ~ "" ~:::- ~~~\!Y r [, I 17~b 61 t'-j\' ~ '\: '17' 40 2.3" ~26J47~~'\ '\"" ~~ ~ "": '\" i:"\.~ ~@' .- G) CD ~ , + @ L~~ 35 ~~ ~
Q/60 l~f ~?60 ~~ ~~ ~.5j 78 ~72 @t . @~ ,~ 9 I. 5 I. "'I. ~ CI t'\'\ ~ ~
I 59 ~)'g~ ~~ 59 ~0 ~"0 45 ~ ~ " "f'\( '- """"" .~~ 29 :24 7 48
~ @ CD H--'@o CD @ 0 ~""'''''6'"'''''",'',,1@ @ lD @ ~< ~
\
~ 3 01 -: 2 1 ~1 r 34 071-. 38 ~'-SSi, "~~ l~""6~'S:J l~'065,~"'''''\j@I • t@ ~ l'.'Zzl'\0 @r*;,
~ ~ - ~ ~ @ 62 32 r 33 JE'3] -~ ~@ (Pl)--4: 17 hl~ ~~.!J~22!?S: 3£0. ~ 67)....~ 73 ~@ @ @~ 1551 /':. - :tf 19 20 t'5t 21 y . ~ . T 42 43 4/, 1--1'6) " ~ ~ 18 20 8)5~ ~~5)+ 1);\+ JI tc',' @T ~ ~J~~ ""J.I,~ ~J2~~ ~ II. T~' @ 01\.... :~ ~ 0 lti ~ ~~@o ~": ~ r ~i22 ~ 29 ~ 79 ~ h 74 ~ 3) !'111F0 10t 16 f~ ~ ~t f ~ ~ ~LJ
''\: ,): t,' f-@@hIT rm' ~4 I~7,0 12 71 13 t 17 36 't6)~ 59 28 39 78 ~3 8c ~'-" ['\...~ l'\'\ ",,-: :, 3 i1 0::
1 @ f.Y I 1:'\" '-- -"'''' 30+ + ~ f:"-",,\ l-/ 15 ~~ ~ 23 ~ '#. ~ 75 9~
~ ~ ~ Sf 27 ~ 77 j_o I~-il'~~' 3~ 79~ ~~
@ ~ @t t~ t9i' ~K~24 ~JJ 26 h'i\~ 76 ~~ ~i ~~
~B).r ~ 1"@fss:i 25
t\~~"'~"'''\'''0~5,{}0.''''''''",,,,~,,,,\~
"
Figure A-l. ISP-13 DRUFAN nodalization for the GRS blind calculation.
8qb
@ Pressurizer
o Control volume
EJ Heal slab
#- Junction
Upper plenum
3reak plane
@
,"..)
Figure A-2. ISP-13 ISP-13 RELAP4jMOD6 nodalization for the JAR blindcalculation.
•
( \\". /., •
Stearn outletI~
o
3reGk
Junction
node
mixing Junction
I~
--1 r--
~ol"'"T
4BPressurizer
Accu mulator
SG secondarysystem49
6j~ SG p"mcry U SG simulator
7} 41 system rl-__.lJ I42 Upper plenum 35. 36
4~ I32I 10' 31
Ccru /::7 I 303 I Ir---" ~25 .r- _ 37 38
JoPump ~Ot 12 I bypass 0 ~9 ,~ creOr"
L. 'OI~' 13 10 24 I ,I 39
Pum 23 28P 44 I Reflood asSist line 40
_ II _ 43 22I 0 0 Core 12147 I' 45 HPI S LP1S 14 20 I 1 'Core bypass
n 501!~1 , 191 126'---' f 8I
46 17 Io, 15 ,116
, \ ''" Lower plenum
Downc.mer
feed',voterIn Ie t
Figure A-3. ISP-13 THYDE-Pl nodalization for the JAT blind calculation,
, ", ' ....... ' ~ .,' ,I." 'ot', •• ~:,j••j
. ~\
l
:. IAi------ ------[JV1 ~ 5--- L________~ 'v
1[iJ
[jFigure A-4a. ISP-13 RELAP4/MOD6 nodalization for the CERL blind calculation -
system components., .. ', .. "'-,.~. ..,... .. .' .: ;: .. '
.. ... " .. , .: . .: ..' ~' " . ';. ,'... ..
-..... " .. ;,;..... '::, '-. "
,.' ,
' .. ::-:.;.':
co''-+-'res
:::lu
resu
-0C
I\,",,~ ..
res-0oC
l..OCl •0....-:::E:: ''-____ res
<:j" +-'C1- (])c::J:: -0....JW +-'o:::c
(])
(V) C....-0I 0-CLE
VJ 0t'-< U
l.L
.0
....J~l.L1U
(])J::+-'
~o4-
~,/ :.!:_;-- '',of. .;. ,:\.1
~ ":y'N
~-I~'lJ !
---L~j
. .:;, .. ' ;'. '.,::. ':.:.. ;:::"
'; ,.r
550 555
305
806
2
306
315
350
215
225
235230
3
2
425
2
426
E25
4' 5
620
612
611
610
615
605
545
120
530
1
115
8
520
Figure A-5, ISP-13 RELAP5jMODl nodalization for the STUD blind calculation.
ATIACHMENT 1
lS Stum Generiltor
@
0 VolumrsJunctions I @.. Huf slatu
31 Volumes36 Junctions12 Hut ,lab,
""a1 plan.
Brule plilne
Broken loop hotleg simuliltion
<D
<D
C0
o
Pressure Vessel
PreS5urizcr
@36@
@
Atcumul~tor....
.. Figure A-6. ISP-13 RELAP4jM006 nodalization for the EIR blind calculation .
I"~"I
~\,.1£) 0.~~. . . i;.
t""....._:~::.'.., ..
.. I.3S Sh~m Generator ATTACHMENT
Q}
Bre~k PI~ne
Broken loop
Volumes
Junctions
Heat Slabs
Bre~k Plane
Core Hut Slabs
Heat Slabs
Junctions
Volumes
•
Pr'.slu ri-z e r
@16
@
@
0,I I I Imffi~1 ~l1 IIntact LoopI I I 1t/f 1h'J..:i\1 I. (3) 00 VJ 1 rzza
@ }-t><l-J I I. I 37
20lZZZZlZlZZI;ZZZZZzzzd .
41Accumul~tor .12
20
;.:;.
:.':".
Figure A-7. ISP-13 RELAP4/MOD6 nodalization for the ErR open calculation .
.. :.\
CJ
.~
~
TEE Q3)
CD COMPONENT NUMBERSCD JUNCTION NUMBERS
VESSEL
OJI I[TIHOT LEGS.--f9l COLD LEGS~ []
TEE TEE@ @ @)
O]JTEE
@
~
@I
I f
[Q)
PRESSURIZER
2
[[]~ [IJ
o
ACCUMULATOR! ~[?J
3
STEAMGENERATOR
.. I NTACT LOOP BROKEN LOOPFigure A-8. ISP-13 TRAC-PD2 nodalization for the LANL open calculation.
('•.... tJi'.'~";;:""f.' ';"- -~;l;._!.:~;
~\=,..-)!
" , , 'P
._~~.. ,I I ..
2]
;.::-
..
".;,'
J.f)
~tj "4'I~ .. I> I.J
1 '3
'~~ LM'dl~ ,71 ,
I 3~ 0EJt><r .25
262'~
, ,\~ I
Ii
(ij)vOll1me
!Y junctionN slab
;~
Figure A-g. ISP-13 RELAP4/MOD6 nodalizqtion for the ENEL blind calculation .
....._t4W4&_~lIiiSW¥¥#.!1"'Ij ....& $00 1¥i@%@&!\jliiM4i\!\NWl>Bl!ltml~l1'~~~~
~fi : .~]\.:;~;_~;..:I
.. " I ..
I J.f-'
:'4
30
calculation.ISP-13 RELAP4/MOD6 nodalization for the DCMN open
3-4
28
Figure A-10.
30
!I~
'f",;~/:: : .. ~,~~;{:~;
.12e )7
25 S
o
.. 15
.16
7
::::::::~~'::::::::::::::
31
2)
l/) l/)
8
22
21
(
HI
.'
o Control volume=: Junction
..
Accumulator @ 53
@
Prcssurl;:cr
Upper plenum
35 CD 2
860Q 2f~IQ
._~.~-c) -~':ll-~(s~ r: J1\::. Jfl
--- 2Cl 2J- fr.~3 - -' t:?7\2~F57 '-
(~"033 3?
@
Sl0am generatorsimulntor
Break plane
r=J c=J CJ@
Pressure suppression system
I", _! ,. ..
-;,/
Figure A-ll. ISP-13 RELAP4/MOD6 nodalization for the CEA blind calculation,
=M..,
Figure A-12. ISP-13 RELAP5jMODl nodalization for the VTT open calculation .
-~-11-4
375
~
235
245
252
251
.... ' ..... , I .J.JV J-I Junction
~ GJ Volure
~ Heat slab
106
..... :
-- .~.to....._.- ~_ ...f'.~'; -~
"t" ..)joo-l.""
rRC FORM 335 u.s. NUCLEAR REGULATORY COMMISSION1. REPORT N UMBE R (Assigned by DOC)
/11.811
I) BIBLIOGRAPHIC DATA SHEET EGG-NTAP-6276TITLE AND SUBTITLE 2. (Lewe blllnk)
International Standard Problem 13(LOFT Experiment L2-5) 3.RECIPIENT"SACCESSION NO.n~~' ;~;n"'Y'\I ~ . n
7. AUTHOR (SI v5. DATE REPORT COMPLETED
MONTH I YEARJ. D. Burtt, S. A. Crowton Aori 1 1983
9. PERFORMING ORGANIZATION NAME AND MAILING ADDRESS Iinciude Zip Code) DATE REPORT ISSUEDMONTH I Yf~3April
EG&G Idaho, Inc. 6. ILeave blank)
Idaho Falls, 10 834158. ILeave blank)
12.SPONSORING ORGANIZATION NAME AND MAILING ADDRESS Iinciude Zip Code) 10.PROJECT/TASK/WORK UNIT NO.Division of Accident EvaluationOffice of Nuclear Regulatory Research 11. FINNO.U.S. Nuclear Regulatory Commission A6047Washington, DC 20555
13.TYPE OF REPORT I PERIOO COVE RE0 /Inclusive dates)
Technical Report15. SUPPLEMENTARY NOTES /14. ILeave bliJf1k)
16.A8STRACT 1200 words or less)
LOFT Experiment L2-5 was designated International Standard Problem 13 by the)rganization for Economic Cooperation and Development. Comparisons between
Imeasurements from Experiment L2-5 were made with calculations from 11 Interna-tional participants using five different computer codes. LOFT Experiment L2-5simulated a double ended guillotine cold leg rupture of a primary coolant loopof a large pressurized water reactor, coupl ed with a loss of offs ite power.
17. KEY WORDS AND DOCUMENT ANALYSIS 17a. DESCRIPTORS
7b. IDENTIFIERS/OPEN.ENDED TERMS
18.AVAILABILITY STATEMENT 19. SECURITY CLASS 171>,s reporr) 21 NO OF PAGESUnclassifiedUnl imited 20.1JCURITY CLASS 171>,s pagel 22 PRICEnclassifierl S
NRC FORM 335 111811