NUREG/IA-0169

International 

Agreement Report 

Analysis of KS-1 Experimental Data 

on the Behavior of the Heated Rod 

Temperatures in the Partially 

Uncovered VVER Core Model 

Using RELAP5/MOD3.2 

Prepared by 

V A. Vinogradov, A. Y. Balykin 

Nuclear Safety Institute 

Russian Research Centre 

"Kurchatov Institute" 

123182, Moscow 

Russia 

Office of Nuclear Regulatory Research 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001 

November 1999 

Prepared as part of 

The Agreement on Research Participation and Technical Exchange 

under the International Code Application and Maintenance Program (CAMP) 

Published by 

U.S. Nuclear Regulatory Commission
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NUREG/IA-0169

International 

Agreement Report 

Analysis of KS-1 Experimental Data 

on the Behavior of the Heated Rod 

Temperatures in the Partially 

Uncovered VVER Core Model 

Using RELAP5/MOD3.2 

Prepared by 

V A. Vinogradov, A. Y. Balykin 

Nuclear Safety Institute 

Russian Research Centre 

"Kurchatov Institute" 

123182, Moscow 

Russia 

Office of Nuclear Regulatory Research 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001 

November 1999 

Prepared as part of 

The Agreement on Research Participation and Technical Exchange 

under the International Code Application and Maintenance Program (CAMP) 

Published by 

U.S. Nuclear Regulatory Commission
ABSTRACT 

This report has been prepared as a part of the Agreement on Research Participation and Technical 

Exchange under the International Code Application and Maintenance Program. 

KS-i Test 35-1 data on the behaviour of the heated rod temperatures in the partially uncovered 

VVER Core model were simulated with RELAP5/MOD3.2 to assess the code, especially its non

equilibrium (unequal phase temperatures) heat transfer models for modeling phenomena in partially 

uncovered core under Small Break LOCA conditions. 

The test has been carried out at experimental section KS-I of the test facility KS (RRC KI) in 1991. 

KS-1 experimental section (VVER Loop model) includes models of all main elements of VVER 

type reactor, loop hot leg model and cold leg simulator, and also horizontal SG tube bundle 

simulator with passive heat removal. Core model consists of 19 electrically heated rod simulators 

with diameter 9 mm and height 2.5 m. 

Test 35-1 models thermal and hydraulic processes during reflux condenser mode in primary circuit 

with low mixture level in partially uncovered VVER core under conditions of small residual heat 

power, middle pressure and counter current flow in the core. 

First a study of the effect of the hydraulic nodalization to the code calculations was performed using 

different number of hydraulic volumes for Core model. After the choice of proper nodalization and 

maximum user-specified time step, base case calculations were done for the test. The differences 

between code predictions for behavior of rod simulator temperatures along the height of Core model 

and test data are described and analyzed. 

Sensitivity studies were carried out to investigate the effects of modeling on the behavior of the rod 

simulator temperatures along the height of Core model.

iii
Table of Contents 

1. INTRODUCTION 1 

1.1. Objectives 1 

1.2. Background 1 

1.3. Study Description 1 

1.4. Report Organization 2 

2. EXPERIMENTAL FACILITY DESCRIPTION 2 

2.1. Description and Characteristics of KS-I VVER Loop Model 2 

2.2. Main Components Characteristics 4 

2.3. Measurements and Errors 9 

3. KS-1 TEST 35-1 DESCRIPTION 13 

3.1. Experiment performance technique. 13 

3.2. Initial and Boundary Conditions 15 

3.2.1. Boundary conditions at the outer surfaces of KS-i VVER Loop model. 

Heat losses 15 

3.2.2. Initial and boundary conditions inside of the coolant circulation circuit 17 

3.3. Experimental limitations and shortcomings 18 

3.4. Experimental Data Used 18 

4. DESCRIPTION OF RELEASED CODE VERSION AND BASE CASE 

INPUT DESKS 21 

4.1. Code Description 21 

4.2. Input Deck Development 21 

4.3. Determinative and determined parameters for code simulation of the 

experimental conditions and analysis of investigated processes/phenomena 24 

4.4. Method of code simulation of initial and boundary conditions with 

RELAP5/MOD3.2 27 

5. RESULTS 37

V
5.1. Nodalization, including variations from base case 37 

5.2. Base Case Results of calculations, Comparison to KS-lTest35-1 and Conclusions 38 

5.3. Sensitivity Studies, including input deck modifications 43 

5.4. Run Statistics 46 

6. SUMMARY OF CONCLUSIONS 47 

7. REFERENCES 48 

Appendix- A: Original Date Plots from KS-1 Test 35-1 A-1 

Appendix- B : Base Case Results B-1 

Appendix- C : Sensitivity Studies C-1 

Appendix- D : Base case input deck D-1 

LIST OF FIGURES 

Fig. 2.1. Scheme of KS-1 VVER Loop model 3 

Fig. 2.2. Model of the VVER core 6 

Fig. 2.3. Model of the VVER-1000 fuel assembly 7 

Fig. 2.4. Measurements in KS-1 VVER Loop model 12 

Fig. 2.5. Scheme of location of the thermocouples TWi-k and pressure sampling 

points along the FA model height 14 

Fig. 4.1. Base case nodalization scheme for RELAP5/3.2 modeling of KS-I Test 23 

Fig. 4.2. Variation of FA model power W (t), correctional coefficient of heat losses 

Closs(t) and coolant mass inventory M=ML+Mg in the closed loop during calculation 

procedures for modeling of KS-I Test (tcal=0-600 s) 31 

Fig. 4.3. Comparison of RELAP5/MOD3.2-calculated Pout (t)cal (tcal=0-600 s) and 

experimental Pout (t)exp curves of pressure decrease, and also selection of time 

interval, corresponding Dtexp, and selection of time moment tlcal, corresponding 

tOexp for KS- I Test 31

vi
Fig. 4.4. RELAP5/MOD3.2-calculated DPt (t) Core model total differential pressure, 

DPu (t) core upper part differential pressure and DPb (t) core bottom part differential 

pressure histories, and also selection of time interval, corresponding Dtexp, and 

selection of time moment tIcal, corresponding t0exp for KS-I Test (tcal=0-600 s) 32 

Fig. 4.5. RELAP5/MOD3.2- calculated Ggl (t) mass flow rate of generated steam and 

GLO (t) steam condensate mass flow rate histories under CCF conditions at Core 

model outlet (tcal=0-600 s), and also selection of time interval, corresponding Dtexp, 

and selection of time moment t Ical, corresponding tOexp for KS-I Test 32 

Fig. 4.6. RELAP5/MOD3.2-calculated TW (t) heated tube inside wall temperatures 

histories in the upper, middle and bottom parts of the FA model (tcal=0-600 s), and 

also selection of time interval, corresponding Dtexp, and selection of time moment 

t I cal, corresponding t0exp for KS- I Test 35 

Fig. 4.7. Comparison of measured and RELAP5/MOD3.2-calculated heated tube 

inside wall temperatures histories in the bottom part of FA Model and also selection 

of time interval, corresponding Dtexp, and selection of time moment t1cal, 

corresponding t0exp for KS- I Test. 36 

Fig. 5.1. Comparison of RELAP5/MOD3.2-calculated core axial inside wall 

temperatures profile in the bundle heated tube for time moment tcal= 365 s, 

corresponding tOexp for KS-i Test, and experimental core axial distribution of 

temperatures of rod simulators TWi-k of the FA Model for time moment tOexp. 41 

Fig. 5.2. The effect of maximum user-specified time step on the calculated inside wall 

temperatures histories in the upper, middle and bottom parts of the bundle heated tube 

(tcal=0-600 s), and also selection of time interval, corresponding Dtexp, and selection 

of time moment tical, corresponding t0exp for KS-I Test.. dtmax=0.2 s. 45 

Fig. 5.3. The required CPU time in the base case calculation. 46 

Fig. 5.4. Time step size of base case calculation. 46 

Fig. A-1. FA model heat release power W (t) history (texp=0-100 s) A-2 

Fig. A-2. Measured Pout (t) Core model outlet pressure history (texp=0-100 s) A-2 

Fig. A-3. Measured TFin (t) Core model inlet coolant temperature history (texp=0

100 s) A-3 

Fig. A-4. Measured TFfa (t) FA model outlet and TFup (t) UP model inlet coolant 

temperatures histories (texp=0-100 s) A-3

vii
Fig. A-5. Measured DL13-12 (t) UP model, DL2-4 (t) and DL4-14 (t) DC model 

differential pressure histories (texp=0- 100 s) A-4 

Fig. A-6. Measured DP4-3 (t), DP5-4 (t), DP6-5 (t), DP7-6 (t), DP8-7 (t), DP9-8 (t) 

and DP 11-10 (t) Core model differential pressure histories (texp=0- 100 s) A-4 

Fig. A-7. Measured TW06-00 (t), TW 12-00 (t), TW 16-00 (t) and TW 18-00 (t) heated 

tube inside wall temperatures histories at the top of FA model (texp=0-100 s) A-5 

Fig. A-8. Measured TW03-02 (t), TW04-03 (t) and TW13-03 (t) heated tube inside 

wall temperatures histories in the upper part of FA model (texp=O-100 s) A-5 

Fig. A-9. Measured TW07-04 (t), TW14-04 (t), TW04-06 (t) and TW13-06 (t) heated 

tube inside wall temperatures histories in the upper part of FA model (texp=0-100 s) A-6 

Fig. A-10. Measured TW14-07 (t), TW03-08 (t), TW04-09 (t) and TW13-09 (t) 

heated tube inside wall temperatures histories in the upper part of FA model (texp=O

100 s) A-6 

Fig. A-11. Measured TW14-10 (t), TW07-10 (t) and TW03-11 (t) heated tube inside 

wall temperatures histories in the middle part of FA model (texp=O- 100 s) A-7 

Fig. A-12. Measured TW04-12 (t), TW02-13 (t) and TW19-15 (t) heated tube inside 

wall temperatures histories in the middle part of FA model (texp=0- 100 s) A-7 

Fig. A-13. Measured TW09-16 (t), TW02-16 (t) and TW17-16 (t) heated tube inside 

wall temperatures histories in the middle part of FA model (texp=O- 100 s) A-8 

Fig. A-14. Measured TW19-18 (t), TW09-19 (t) and TW17-19 (t) heated tube inside 

wall temperatures histories in the bottom part of FA model (texp=O-100 s) A-8 

Fig. A-15. Measured TW19-21 (t), TW02-22 (t), TW17-22 (t) and TW19-24 (t) 

heated tube inside wall temperatures histories in the bottom part of FA model 

(texp=0-100 s) A-9 

Fig. B-1. RELAP5/MOD3.2-calculated Pout(t)cal pressure at Core model outlet B-2 

(tcal=0-600 s). 

Fig. B-2. Comparison of measured Pout(t)exp and RELAP5/MOD3.2-calculated 

Pout(t)cal pressure at Core model outlet (texp=O- 100 s). B-2 

Fig. B-3. Comparison of measured and RELAP5/MOD3.2-calculated Tfin (t) coolant 

temperature at Core model inlet (texp=0- 100 s). B-2 

Fig. B-4. RELAP5/MOD3.2-calculated TW(t) heated tube inside wall temperatures 

histories in the upper, middle and bottom parts of the FA model (tcal=0-600 s). B-3

viii
Fig. B-5. RELAP5/MOD3.2-calculated void fractions histories in the bottom part of 

FA channel (tcal=O- 600 s). B-4 

Fig. B-6. Behavior of RELAP5/MOD3.2-calculated Hwl (t) coefficient of heat 

transfer from outer surfaces of rod simulators to coolant in the upper, middle and 

bottom parts of FA model (tcal=0-600 s). B-5 

Fig. B-7. Behavior of RELAP5/MOD3.2-calculated qwl (t) specific heat flux from 

outer surfaces of the rod simulators to coolant in the upper, middle and bottom parts 

of FA model (tcal=0-600 s). B-6 

Fig. B-8. RELAP5/MOD3.2-calculated Vg (t) junction vapor velocities histories in 

the upper, middle and bottom parts of FA channel (tcal=0-600 s). B-7 

Fig. B-9. RELAP5/MOD3.2-calculated VL (t) junction liquid velocities histories in 

the upper, middle and bottom parts of FA channel (tcal=0-600 s). B-8 

Fig. B-10. RELAP5/MOD3.2-calculated Ti (t) insulator inside wall temperatures 

histories in the upper, middle and bottom parts of the FA model (tcal=0-600 s). B-9 

Fig. B-11. Behavior of RELAP5/MOD3.2-calculated Hw2 (t) coefficient of heat 

transfer from coolant to the insulator in the upper, middle and bottom parts of FA 

model (tcal=0-600 s). B-10 

Fig. B-12. Behavior of RELAP5/MOD3.2-calculated Hw3 (t) coefficient of heat 

transfer from outer surface of steel shroud to coolant on the height of Core model 

annular gap (tcal-0-600 s). B-i1 

Fig. B-13. Behavior of RELAP5/MOD3.2-calculated Hw4 (t) coefficient of heat 

transfer from coolant to inner surface of pressure vessel on the height of Core model 

annular gap (tcal=0-600 s). B-12 

Fig. B-14. Comparison of measured and RELAP5/MOD3.2-calculated Tffa (t) FA 

model outlet and Tfup (t) UP model inlet coolant temperatures histories (texp= 0-100 B-13 

s). 

Fig. B-15. Comparison of measured TW06-00 (t), TW12-00 (t), TWl6-00 (t), TW18

00 (t) and RELAP5/MOD3.2-calculated heated tube inside wall temperatures 

histories at the top of FA model (texp=O-100 s) B-13 

Fig. B-16. Comparison of measured TW03-02 (t), TW04-03 (t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

upper part of FA model (texp=0- 100 s) B-14

ix
Fig. B-17. Comparison of measured TW07-04 (t), TW04-06 (t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

upper part of FA model (texp=0- 100 s) B-14 

Fig. B-18. Comparison of measured TW03-08 (t), TW04-09 (t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

upper part of FA model (texp=0- 100 s) B-15 

Fig. B-19. Comparison of measured TWl4-10 (t), TW07-10 (t), TW03-11 (t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

middle part of FA model (texp=0-100 s) B-15 

Fig. B-20. Comparison of measured TW04-12 (t), TW02-13 (t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

middle part of FA model (texpO---100 s) B-16 

Fig. B-21. Comparison of measured TW09-16 (t), TW02-16 (t), TW17-16 (t) and 

RELAP5/MOD3 .2-calculated heated tube inside wall temperatures histories in the 

middle part of FA model (texp=0-100 s) B-16 

Fig. B-22. Comparison of measured TWl9-18 (t), TW09-19 (t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

bottom part of FA model (texp=0- 100 s) B-17 

Fig. B-23. Comparison of measured TW19-21 (t), TW02-22 (t), TW19-24 (t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

bottom part of FA model (texp=0- 100 s) B-17 

Fig. C-1. RELAP5/MOD3.2-calculated TW (t) heated tube inside wall temperatures 

histories in the upper, middle and bottom parts of the FA model (tcal=0-600 s). 

Maximum time step =0.01 s. Restart time t=365 s. C-2 

Fig. C-2. RELAP5/MOD3.2-calculated TW (t) heated tube inside wall temperatures 

histories in the upper, middle and bottom parts of the FA model (tcal=0-600 s). 

Maximum time step =0.2 s. Restart time t=365 s. C-3 

Fig. C-3. Comparison of measured Pout (t)exp and RELAP5/MOD3.2-calculated 

Pout(t)cal pressure at Core model outlet (texp=O-100 s) C-4 

Fig. C-4. Comparison of measured TW06-00 (t), TWl2-00 (t), TWl6-00 (t), TW18

00 (t) and RELAP5/MOD3.2-calculated heated tube inside wall temperatures 

histories at the top of FA model (texp=O-100 s). C-4

x
Fig. C-5. Comparison of measured TW03-02 (t), TW04-03 (t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

upper part of FA model (texp=O- 100 s) C-5 

Fig. C-6. Comparison of measured TW07-04 (t), TW04-06 (t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

upper part of FA model (texp=O- 100 s) C-5 

Fig. C-7. Comparison of measured TW03-08 (t), TW04-09 (t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

upper part of FA model (texp=O- 100 s) C-6 

Fig. C-8. Comparison of measured TW14-10 (t), TW07-10 (t), TW03-11 (t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

middle part of FA model (texp=0-100 s) C-6 

Fig. C-9. Comparison of measured TW04-12 (t), TW02-13 (t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

middle part of FA model (texp=0- 100 s) C-7 

Fig. C-10. Comparison of'measured TW09-16 (t), TW02-16 (t), TW17-16 (t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

middle part of FA model (texp=0-100 s) C-7 

Fig. C-11. Comparison of measured TW19-18 (t), TW09-19 (t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

bottom part of FA model (texp=0-100 s) C-8 

Fig. C-12. Comparison of measured TW19-21 (t), TW02-22 (t), TW19-24 (t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

bottom part of FA model (texp=0-100 s) C-8 

Fig. C-13. Behavior of RELAP5/MOD3.2-calculated Hwl (t) coefficient of heat 

transfer from outer surfaces of rod simulators to coolant in the upper, middle and 

bottom parts of FA model (tcal=0-600 s), dtmax=0.01 s Restart t=365 s. C-9 

Fig. C-14. Behavior of RELAP5/MOD3.2-calculated Hwl (t) coefficient of heat 

transfer from outer surfaces of rod simulators to coolant in the upper, middle and 

bottom parts of FA model (tcal=0-600 s), dtmax=0.2 s Restart t=365 s. C-10

xi
LIST OF TABLES 

Table 2.1. Main parameters of KS- 1 VVER Loop Model 4 

Table 2.2. Parameters of Core model with VVER- 1000 fuel assembly model 5 

Table 2.3 List of measured parameters used in calculations, measurement ranges and 

errors 9 

Table 3.1 Estimated heat transfer coefficients Kloss(Do) for different parts of 

experimental circuit 16 

Table 3.2. Initial values of determinative parameters of KS-1 Test 35-1 for quasi

steady regime 19

xii
EXECUTIVE SUMMARY

KS-1 Test 35-1 data on the behavior of the heated rod temperatures in the partially uncovered 

VVER Core model were simulated with RELAP5/MOD3.2 to assess the code. These calculations 

were performed to evaluate the general code prediction capability in modeling reflux condenser 

mode in the primary system of a reactor VVER , as well as specific problem areas of the code in 

modeling non-equilibrium (unequal phase temperatures) heat transfer in partially uncovered core 

under Small Break LOCA conditions with counter current flow. 

Test 35-1 has been carried out at experimental section KS-1 of the test facility KS (RRC KI) in 

1991. KS-1 VVER Loop model is semi-integral one loop model of VVER primary system for 

investigations hydrodynamics and heat transfer in transients and SBLOCA conditions of a reactor. 

KS- I experimental section includes models of all main elements of VVER type reactor, loop hot leg 

model and cold leg simulator, and also horizontal SG tube bundle simulator with passive heat 

removal. Core model consists of 19 electrically heated rod simulators with diameter 9 mm and 

height 2.5 m. 

Test 35-1 models thermal and hydraulic processes during steam and condensate circulation in 

primary circuit with low mixture level in partially uncovered VVER core under conditions of small 

residual heat power, middle pressure and counter current flow in the core. The objectives of the test 

are - to obtain test data on core axial and FA radial distributions of rod simulators temperatures 

under quasi-steady conditions; - determination influence of thermal and hydraulic processes in the 

models of circuit elements on the processes in the Core model, including influence of heat losses 

from the circuit to environment on heat transfer in partially uncovered core. Specific feature of this 

test is relatively high intensity of heat transfer from rod simulators to the coolant in uncovered part 

of FA model under influence of circuit heat losses and steam condensation in the models of circuit 

elements on the processes. During cooling of FA model under conditions of counter current flow, 

non-uniform core axial and FA radial distributions of rod simulator temperatures were obtained. 

Measured maximum value of cladding temperature occurs inside the Core model. 

First a study of the effect of the hydraulic nodalization to the code calculations was performed using 

different number of hydraulic volumes for Core model. After the choice of proper nodalization and 

maximum user-specified time step, base case calculations were done for the test. The differences 

between code predictions for behavior of rod simulator temperatures at various cross sections along 

the height of Core model and test data are described and analyzed.

xiii
Sensitivity studies were carried out to investigate the effects of modeling on behavior of rod 

simulator temperatures along the core height. 

In this work some deficiencies of RELAP5/MOD3.2 in analysis of KS-i Test 35-1 could be 

identified, and the following conclusions can be drawn: 

* RELAP5/MOD3.2 gives a satisfactory agreement of calculation results and test data for overall 

picture of the two-phase flow behavior in KS-iVVER Loop model and heat transfer in partially 

uncovered Core model during reflux condenser mode with some exceptions. 

* There is a significant quantitative and qualitative difference of calculated and measured core axial 

temperature profiles in the heated FA model. RELAP5/MOD3.2 under predicts TW (tcal) 

temperatures in the middle part of FA model and over predicts ones at the FA outlet. 

e In considered "quasi steady regime" calculated TW (tcal) wall temperature is much higher (up to 

130 K) than measured ones at the FA outlet. This is one of the main problems of the code base case 

calculations. The reason for these deviations between experiment and calculations is too low Hwl 

(tcal) z 50-60 W/m2.K (tcal) coefficient of heat transfer from outer surfaces of rod simulators to 

coolant in the upper part of FA model calculated for CCF conditions. Therefor, calculated 

temperature increase rate dTW/dt is much more, than measured ones. In this case under prediction 

for interphase heat transfer may be the other reason for these deviations between experiment and 

calculations. 

e In considered "quasi steady regime" calculated wall temperature TW (tcal) is much lower (100 K 

below) than measured ones in the middle part of FA model. This is the next one of the main 

problems of the code calculations. The reason for these deviations between experiment and 

calculation is too large Hwl (tcal) z 80 W/m 2.K coefficient of heat transfer in the middle part of FA 

model calculated for CCF conditions. 

* Sensitivity studies shows, that implementation experimental temperature profile in restart input 

deck allow to reduce large differences between code predictions and measurements for core axial 

temperature profiles at the initial moment t0exp and then during the test simulation. However, initial 

temperature conditions in FA model weakly influence on code simulation of heat transfer and 

interphase heat exchange in partially uncovered core under CCF conditions.

xiv
NOMENCLATURE 

W - power of FA model, kW 

qv- specific volumetric power, kW/ m3 

qw- heat flux, kW/m 2 

Pout - core model outlet pressure, bar 

DP- pressure difference, kPa 

DL13-12 - measured pressure difference on difmanometer, connected to points 13 and 12 of the UP 

model, in levelmeter regime, bar, Pa 

DL2-4 - measured pressure difference on difinanometer, connected to points 2 and 4 of the 

downcomer model, in levelmeter regime, bar, Pa 

DL4-14 - measured pressure difference on difinanometer, connected to points 4 and 14 of the 

downcomer model, in levelmeter regime, bar, Pa 

DL4-3, DL5-4, DL6-5, DL7-6, DL8-7, DL9-8, DLl1-10 - measured pressure difference on 

difrnanometer, connected to the core model in corresponding points of heated part of rod bundle 

model, in levelmeter regime, kPa, Pa 

Lm - mixture level, in 

TFin - water temperature in lower plenum model, 'C 

TFup - coolant temperature in UP model inlet, 'C 

TFfa - coolant temperature in FA model outlet, 'C 

TFdc - coolant temperature in DC model, 'C 

TWi-k - inner side temperature of rod heated wall, 'C 

Ts - saturation temperature 

Tg - vapor temperature 

D - diameter, mm 

Dh - hydraulic diameter of the channel, mm 

AL - distance between points of pressure difference measurement, mm 

A4 - distance between the bottom cross section of heated zone of FA model and cross sections 

k=00-24 along the FA height where thermocouples are installed, mm 

- local hydraulic resistance coefficient 

GL -liquid mass flow rate, kg/s 

Gg -vapor mass flow rate, kg/s 

VL - liquid velocity, m/s 

XV
Vg - vapor velocity, m/s 

Hw - heat transfer coefficient, W/m 2 s 

t-time, s 

i = 01-19 - number of FE 

k = 00-24 - number of cross sections from top to bottom of fuel assembly, where thermocouples 

have been installed 

exp - experimental value 

cal - calculated value 

RRC KI - Russian Research Center "Kurchatov Institute" 

VVER - Russian light water reactor 

SBLOCA - small break loss of coolant accident 

UP - upper plenum 

DC - downcomer 

SG - steam generator 

FA - fuel assembly 

MCC - main circulation circuit 

DAS - data acquisition system 

NC - natural circulation 

CCF - counter current flow 

CCFL - counter current flow limitation

xvi
1. INTRODUCTION

1.1. Objectives 

The main goals of this work are: - analysis of the KS-1 experimental data on the behavior of rod 

temperatures in the partially uncovered VVER Core model using RELAP5/MOD3.2; investigation 

thermal and hydraulic processes during steam and condensate circulation in primary circuit with low 

mixture level in the Core model under conditions of small residual heat power, middle pressure and 

counter current flow in the core; evaluation of the general code prediction capability in modeling 

reflux condenser mode in the primary system of a reactor VVER under Small Break LOCA 

conditions; assessment of RELAP5/MOD3.2 code, especially its non-equilibrium (unequal phase 

temperatures) heat transfer models for modeling phenomena in partially uncovered core under 

conditions with counter current flow. 

1.2. Background 

To help ensure RELAP5 code can be used with confidence, Russian Research Centre "Kurchatov 

Institute" has agreed to perform and document independent assessment of the code for a wide range 

of applications. These exercises are necessary to help identify and quantify any code shortcoming, in 

particular for the Russian types of reactors VVER and RBMK. This report has been prepared as a 

part of the Agreement on Research Participation and Technical Exchange under the International 

Code Application and Maintenance Program. Analysis of semi-integral KS-1 Test 35-1 with 

partially uncovered VVER Core model under SBLOCA conditions was performed using the latest 

version of code RELAP5/MOD3.2. 

1.3. Study Description 

SBLOCA is one of the design basis accidents in VVER power pressure water reactor. KS-1 VVER 

Loop model is semi-integral (one loop) model of VVER primary system for investigations 

hydrodynamics and heat transfer in transients and SBLOCA conditions of a reactor. In this facility 

series of the tests with partially uncovered VVER Core model under SBLOCA conditions were 

performed during 1991 year. 

Phenomena of hydrodynamics and heat transfer in VVER core under uncovering conditions are 

specific. So, it is necessary to estimate RELAP'5/MOD3.2 code models adequacy for modeling of 

these phenomena, because there are specific features in design of core and fuel assembly of VVER

440 and VVER-1000. These specific features are FA rod location (triangular grid), geometry of rod 

and FA elements, hydraulic diameters of rod bundle cells and number of space grids. Temperature of

I
rods directly depends on these factors. 

KS-1 Test 35-1 was chosen for assessment calculations with RELAP5/MOD3.2. This code 

capability was investigated. Special emphases were given to: - thermal and hydraulic processes 

during steam-condensate circulation in primary circuit with low mixture level in partially uncovered 

Core model under conditions of small residual heat power and of middle pressure; - non-equilibrium 

heat transfer and core axial temperature distributions in the uncovered part of Core model under 

quasi-steady conditions; - influence of thermal and hydraulic processes in the models of circuit 

elements on the processes in Core model, including influence of heat losses from the circuit to 

environment and of counter current flow on heat transfer in partially uncovered core. 

1.4. Report Organization: The following sections present and describe the steps that were taken to 

facilitate the code assessment. In Section 2 the KS-1 VVER Loop model of the KS Test Facility is 

described, and KS-1 Test 35-1 is described in Section 3. Descriptions of released code version and 

base case input deck for the test modeling are given in Section 4. Nodalization, including variation 

from base case, the results for the base case input deck for the test and analysis of transients, the 

discussion of the calculated and measured values and conclusions are presented in Section 5. 

Sensitivity studies and run statistics are given in Section 5 too. In Section 6 summary of conclusions 

is presented. In the Appendix D one finds the base case input decks including listings for KS-1 Test 

35-1 and sensitivity variation input deck listing. 

2. EXPERIMENTAL FACILITY DESCRIPTION 

2.1. Description and Characteristics of KS-1 VVER Loop Model 

Experimental section KS-I was developed on the base of the test facility KS (RRC KI) for modeling 

of thermal and hydraulic processes in VVER core under SB LOCA conditions. 

Experimental section KS-1 VVER Loop model has been designed for modeling of boiling

condensing mode in VVER primary system and non-equilibrium heat transfer processes in partially 

uncovered core at small residual heat power and for middle and low pressure ranges. It is test facility 

designed for investigations both separate effects and integral thermal and hydraulic processes in 

primary circuit under SB LOCA conditions. Principle scheme of VVER Loop model is shown in 

Fig.2. 1. Main parameters of Loop model are presented in Table 2.1.

2
valve 2 valve 3 

Fig.2.1. Scheme of KS- I VVER Loop model. 

1. Downcomer model 6. SG tube bundle simulator 

2. Lower plenum model 7. SG tube bundle simulator 

3. Core model 8. Loop cold leg simulator 

4. Upper plenum model 9. Lower pipeline 

5. Loop hot leg model

3
Table 2.1. Main parameters of KS-1 VVER Loop model

VVER Loop model consists of: Downcomer model 1, Lower Plenum model 2, Core model 3, Upper 

Plenum model 4, loop Hot Leg model 5, horizontal SG tube bundle simulator with sections 6, 7 with 

passive heat removal, and loop cold leg simulator 8. 

SG simulator only qualitatively simulates hydrodynamics and heat transfer processes under steam 

condensation in the SG tube bundle. Downcomer model at bottom and Lower Plenum model are 

connected by a lower pipeline 9. 

Up-coming and down-coming circuit branches are linked in upper part by pipelines of Hot Leg and 

Cold Leg and by SG tube bundle simulator. So, it forms coolant natural circulation circuit in semi

integral one loop model of VVER primary system. 

Steam pipeline from SG tube bundle simulator into expansion tank to release steam through valve 1, 

water pipeline from lower pipeline 9 into expansion tank to drain water through valve 2, and also 

water pipeline into lower pipeline 9 to feed water through valve 3 serve for formation of initial 

conditions with break of coolant natural circulation and with partially uncovered Core model in the 

test section. 

KS facility and DAS provide preparation and implementation of the planned experiments. 

2.2. Main Components Characteristics 

Downcomer model. The location of the DC model 1 in VVER Loop model is shown in Fig.2. 1. The 

cross section area of the DC model channel with diameter of 80 mm is in 2.8 times greater than cross 

section area of the Core model channel with FA model. This fact provides small variations of 

collapsed level and hydrostatic water head in Downcomer model for time period of registration of 

rod simulator temperatures during investigation of heat transfer in partially uncovered FA model for 

quasi-steady regime.

4

Forced and natural circulation of coolant in the loop

Height of up-coming branch of NC 17.7 m 

Primary circuit pressure P 1-100 bar 

FA model power W 0-100 kW 

Heat flux in FA model qw 0-75 Kw/m2 

Flow rate through the core model at forced circulation GL1 0-833 kg/s.
Core model. Detail drawing of the Core model is presented in Fig.2.2. The cross section of the Core 

model is also shown in Fig.2.2. The Core model consists of: - electrically heated VVER-1000 fuel 

assembly model 1 enclosed by shroud 2 made of 12Xl8Hl0T steel with internal electric and heat 

insulator bushes of talkochlorite 3; pressure vessel tube 4; tubes 5 connected to differential 

manometers for pressure difference measurements along the core height; upper conductor 6 for 

supply of current to rod simulators; unit 7 for gas supply into the of rod simulators tubes with aim to 

unload rod simulators from external coolant pressure and for outlet of thermocouples 8 from FA 

model; lower conductor 9. 

VVER- 1000 fuel assembly model is shown in Fig.2.3. The cross section of FA model is presented 

on Fig.2.3b. The rod simulators are numbered as i=1-19. Parameters of Core model with fuel 

assembly model are presented in Table 2.2. 

Table 2.2. Parameters of Core model with VVER-1000 fuel assembly model 

Heated length of the FA model 2505 mm 

Number of rod simulators 19 

Outer diameter of rod simulators 9.0 mm 

Distance between rod simulators 12.75 mm 

Size of channel hexahedron 59 mm 

Channel cross section area 0.001806 m 2 

Heat transfer surface area of FA model 1.345 m 2 

Hydraulic diameter of the channel 9.75 mm 

Initial axial and radial power distribution uniform 

Height of Core model annular channel 2560 mm 

The annular channel (with gap 51 mm along the whole height of the core) between shroud of the FA 

model and pressure vessel tube is closed at the top. It is connected with the Lower Plenum model 

and filled with coolant - water at the bottom, and saturated or superheated steam at the top.

5
0219×X14 

5 ~00 

0 

41 

10 

0 0 

'0 ý 2505 

to DM -- [. toDM 

Fig. 2.2. Model of the VVER core. 

1. Model of VVER fuel assembly 

2. Shroud of FA model 

3. Insulator bushes 

4. Pressure vessel tube 

5. Differential manometer lines 

6. Upper conductor 

7. Unit for gaseous unload of rod simulators 

8. Thermocouples lines 

9. Lower conductor

6
b)

Fig.2.3. Model of the VVER-1000 fuel assembly. 

a) bundle of the rod simulators 

b) cross section of the FA model 

1. Steel tube of the rod simulator 

2. Space grid 

3. Cooper tube of the upper conductor of the rod simulator 

4. Upper cone of the conductor 

5. Cooper pin of the lower conductor of the rod simulator 

6. Insulator bush 

7. Shroud

7
The rod simulators (see Fig. 2.3 a) have been made of 12X18H1OT stainless steel tubes with outer 

diameter 9.0 mm and wall thickness of 1.53 mm, heated simulator length is 2505 mm. At the top of 

each tube there is a cooper conductor 3 with outer diameter of 9 mm and wall thickness of 2 mm. In 

the heated zone there are 11 space grids of VVER-1000 FA type. Distance between grids is 250 mm. 

All space grids are standard. All 19 sells of space grids have height of 20 mm. They are made of 

12X148H10T stainless steel tubes with outer diameter 13 mm and wall thickness of 0.3 mm. From 

the experimental results the local hydraulic resistance coefficient of the grid is ý=0.26. 

The rod bundle is connected to conducting bus by cooper cones and heated directly by current 

through simulator tubes. 

Upper Plenum model. The location of the Upper Plenum model 4 in VVER Loop model is shown 

in Fig.2. 1. A difference between UP model and real VVER upper plenum is an occurrence of side 

coolant flow after its passing of the Core model. Steam-water mixture moves from the Core model 

into a vertical up-coming path of the UP model via a horizontal branch with inner diameter of 100 

mm and length of 420 mm. There is a stagnation zone below conducting cone where steam and gas 

can be accumulated. 

Loop Hot Leg model. Hot Leg model 5 (see Fig.2.1) is a pipeline made of tube 0 75x5 (Dh=65 

mm). It consists of two straight sections with lengths of 1000 mm and 7400 mm linked by 90 0 

bends with radius of 500 mm. The HL model has a small inclination with angle 10 for liquid 

drainage from HL and from section 6 of SG tube bundle simulator into UP model. The side outlet of 

the UP model is located below point A, which is the highest one of the VVER Loop model. 

Simulator of the steam generator tube bundle. The SG tube bundle simulator (see Fig.2.1) with 

passive heat removal is a pipeline made of tube 0 75x5 (Dh=65 mm) divided by point A into two 

weakly inclined straight sections 6 and 7 with length of 1500 mm each. These sections are linked 

with HL and CL by 90 0 bends with radius of 500 mm. The section 6 is connected to the HL model. 

It is weakly inclined (angle is 10) for liquid drainage to HL model and further into the UP model. 

Another end" of this section is linked to section 7 of the SG tube bundle simulator. The section 7 is 

connected to CL. It is also weakly inclined to another side (1°) for liquid drainage to CL 8 and 

further into the DC model. A pipeline with a valve 1 is connected with tube bundle simulator in the 

point A. This pipeline is used for steam release from the circuit into expansion tank for initial 

condition preparation. It is a pipeline made of tube 0 75x5 (Dh=65 mm) with length 16000 mm. 

This pipeline is also inclined (10) for liquid drainage to the section 6 and section 7. In the point A the 

total flow rate of steam condensate from this pipeline is uniformly distributed on sections 6 and 7. 

8
Loop cold leg simulator. The cold leg simulator 8 (see Fig.2.1) has been made without loop seal. It 

consists of two sections: - pipeline section made of tube 0 75x5 (Dh=65 mm) with length of 6950 

mm, weakly inclined (angle is 10); vertical channel with following size: outer diameter is 114 mm, 

wall thickness is 6 mm. There are internal elements inside this channel. 

Lower pipeline. The Lower pipeline 9 (see Fig.2.1) joins the DC model 1 with the Lower Plenum 

model 2. 

Only SG tube bundle simulator is non-heat-insulated part of the experimental circuit. All other outer 

surfaces of the KS-1 VVER Loop model have been covered by heat insulation for heat loss decrease. 

2.3. Measurements and Errors 

Locations of the gauges in the Downcomer model, Lower Plenum model, Core model, Upper 

Plenum model and Lower pipeline are presented on the scheme of measurements in KS-1 VVER 

Loop model, shown in Fig.2.4. List of measured parameters, and their ranges and measurement 

errors are presented in Table 2.3. 

Table 2.3. List of measured parameters used in calculations, measurement ranges and errors 

N Indentifi- Parameter description Range Error Length, 

cator mm 

1 U Voltage in FA model, V 0-50 ±0.5 % 

2 BI1 Current, A 0÷1500 ±0.5 % 

3 BI2 Current, A 0+1500 ±0.5 % 

4 W Power, kW 0-75 ±2.5 % 

5 Pout Core model outlet pressure, bar 0-100 ±0.16 % 

AL, mm 

6 DL13-12 Pressure difference in the UP 0-1.0 ±1.4 % 7800 

model, bar 

7 DL2-4 Pressure difference in the DC 0÷1.0 ±1.4 % 8875 

model, bar 

8 DL4-14 Pressure difference in the DC 040.63 ±1.4 % 4550 

model, bar 

9 DL4-3 Pressure difference in the heated 0:1.6 ±1.4 % 75 

zone of FA, kPa 

10 DL5-4 Pressure difference in the heated 0÷4.0 ±1.4 % 385 

zone of FA, kPa 

11 DL6-5 Pressure difference in the heated 0+10.0 ±1.4 % 720 

zone of FA, kPa 

12 DL7-6 Pressure difference in the heated 0+6.30 ±1.4 % 480 

zone of FA, kPa

9
13 DL8-7 Pressure difference in the heated 0+6.30 ±1.4 % 480 

zone of FA, kPa 

14 DL9-8 Pressure difference in the heated 0-2.50 ±1.4 % 145 

zone of FA, kPa 

15 DL1 1-10 Pressure difference in the heated 0-1.6 ±1.4 % 40 

zone of FA, kPa 

16 TFin Coolant temperature in the lower 0÷300 ±0.5 % 

plenum model, 'C 

17 TFdc Coolant temperature in the DC 0-300 ±0.5 % 

model, 'C 

18 TFup Coolant temperature in the UP 0÷400 ±1.5 % 

model inlet, 'C 

19 TFfa Coolant temperature in the FA 0-400 ±1.5 % 

model outlet, 'C 

AZk, mm 

20 TW06-00 Temperature of rod simulator 06 0-600 ±3.0 % 2485 

in cross section 00, 'C 

21 TW06SOO Temperature of rod simulator 06 0÷600 ±3.0 % 2485 

in cross section 00, 'C 

22 TWl2-00 Temperature of rod simulator 12 0÷600 ±3.0 % 2485 

in cross section 00, 'C 

23 TW12SOO Temperature of rod simulator 12 0÷600 ±3.0 % 2485 

in cross section 00, 'C 

24 TWl6-00 Temperature of rod simulator 16 0-600 ±3.0 % 2485 

in cross section 00, 'C 

25 TWl8-00 Temperature of rod simulator 18 0-600 ±3.0 % 2485 

in cross section 00, 'C 

26 TW03-02 Temperature of rod simulator 03 0-600 ±3.0 % 2290 

in cross section 02, 'C 

27 TW04-03 Temperature of rod simulator 04 0+600 ±3.0 % 2245 

in cross section 03, 'C 

28 TWl 3-03 Temperature of rod simulator 13 0-600 ±3.0 % 2245 

in cross section 03, 'C 

29 TW07-04 Temperature of rod simulator 07 0+600 ±3.0 % 2135 

in cross section 04, 'C 

30 TW14-04 Temperature of rod simulator 14 0-600 ±3.0 % 2135 

in cross section 04, 'C 

31 TW04-06 Temperature of rod simulator 04 0+600 ±3.0 % 1990 

in cross section 06, 'C 

32 TW13-06 Temperature of rod simulator 13 0-600 ±3.0 % 1990 

in cross section 06, 'C 

33 TW14-07 Temperature of rod simulator 14 0÷600 ±3.0 % 1880 

in cross section 07, 'C 

34 TW03-08 Temperature of rod simulator 03 0÷600 ±3.0 % 1780 

in cross section 08, 'C 

10
35 TW04-09 Temperature of rod simulator 04 0+600 ±3.0 % 1735 

in cross section 09, °C 

36 TW13-09 Temperature of rod simulator 13 0+600 ±3.0 % 1735 

in cross section 09, 'C 

37 TW14-10 Temperature of rod simulator 14 0-600 ±3.0 % 1625 

in cross section 10, 'C 

38 TW07-10 Temperature of rod simulator 07 0+600 ±3.0 % 1625 

in cross section 10, 'C 

39 TW03-1 1 Temperature of rod simulator 03 0-600 ±3.0 % 1525 

in cross section 11, 'C 

40 TW04-12 Temperature of rod simulator 04 0÷600 ±3.0 % 1480 

in cross section 12, 'C 

41 TW02-13 Temperature of rod simulator 02 0÷600 ±3.0 % 1390 

in cross section 13, 'C 

42 TW19-15 Temperature of rod simulator 19 0-600 ±3.0 % 1245 

in cross section 15, 'C 

43 TW09-16 Temperature of rod simulator 09 0÷600 ±3.0 % 1135 

in cross section 16, 'C 

44 TW02-16 Temperature of rod simulator 02 0÷600 ±3.0 % 1135 

in cross section 16, 'C 

45 TW17-16 Temperature of rod simulator 17 0+600 ±3.0 % 1135 

in cross section 16, 'C 

46 TW 19-18 Temperature of rod simulator 19 0-600 ±3.0 % 990 

in cross section 18, 'C 

47 TW09-19 Temperature of rod simulator 09 0-600 ±3.0 % 880 

in cross section 19, 'C 

48 TW17-19 Temperature of rod simulator 17 0÷600 ±3.0 % 880 

in cross section 19, 'C 

49 TW19-21 Temperature of rod simulator 19 0-600 ±3.0 % 735 

in cross section 21, 'C 

50 TW02-22 Temperature of rod simulator 02 0-600 ±3.0 % 625 

in cross section 22, 'C 

51 TW17-22 Temperature of rod simulator 17 0+600 ±3.0 % 625 

in cross section 22, 'C 

52 TW19-24 Temperature of rod simulator 19 0M600 ±3.0 % 480 

in cross section 24, 'C

11
7 8 0 0 PLo u- I 8 8 7 5 

DL2-4 

Pout 

TFfa TFup 

p12 

TFdc 

DL11-10 98 

TWi-k 986 V O DL9-8 __ ____ P

4 

2800 2505 DL8-7 

)DL7-6 1519 

)DL6-5 

DL5-4 4550 DL4-14 

\l/ )DL4-3 ' 

--T~in3031 • 

___ _______ p14 

GLF 2l. 

A A 

Water drain Feed water 

valve. 2 valve. 3 

Fig. 2.4. Measurements scheme in the VVER primary system model.

12
The collapsed levels of the coolant in the UP and DC models were measured with DL13-12, DL2- 4 

and DL4-14 differential manometers with their reverse connection to the pressure samplings. The 

collapsed level of the coolant in the Core model was measured with DL4-3, DL5-4, DL6-5, DL7-6, 

DL8-7, DL9-8, DL11-10 differential manometers with their reverse connection to pressure 

samplings. Location of pressure sampling points and distances AL between these points for the 

differential manometers are presented in Fig. 2.4, Fig. 2.5 and in Table 2.3. 

The coolant temperatures in the Lower Plenum model TFin, at the FA model outlet TFfa, at the 

Upper Plenum model inlet TFup and in the DC model TFdc were measured with chromel-copel 

thermocouples. Measurements of FA model axial and radial temperature distributions were made 

with 33 thermocouples installed inside rod simulators (in 14 rods) on 20 elevations. 

Scheme of location of the thermocouples TWp.k along the FA model height is shown in Fig.2.5. 

The electric power W of the FA model was determined on the base of measurements of voltage drop 

U on the FA model and current. 

Data acquisition system, All above mentioned parameters, i.e. rod simulators temperatures TWi-k, 

coolant temperatures TFin, TFfa, TFup and TFdc, pressure Pout, pressure differences DL13-12, 

DL2-4, DL14-4, DL4-3, DL5-4, DL6-5, DL7-6, DL8-7, DL9-8, DL11-10, voltage U and current, 

were registered by computer. Duration of one sampling was,& 0.3 s. Sampling period was • 0.5 s. 

3. KS-1 TEST 35-1 DESCRIPTION 

3.1. Experiment performance technique 

KS-1 Test 35-1 models thermal and hydraulic processes during reflux condenser mode in VVER 

primary circuit with low mixture level in partially uncovered core under conditions of small residual 

heat power, middle pressure and counter current flow in the core. To establish test conditions it was 

performed preliminary heating of water and pipeline metal up to required coolant temperature at the 

Core model inlet under forced coolant circulation. Then VVER Loop model was isolated from the 

forced circulation circuit of the KS facility. After that a smooth increase of the FA power was 

realized to set single-phase NC regime. Water was heated. Coolant pressure was increased up to 80 

bar, and then coolant drainage from SG tube bundle simulator to expansion tank through the valve 1 

was started. Boiling NC. regime was started under slightly greater pressure Pout and water 

temperature TFin than needed. Some amount of steam was released from the tube bundle simulator 

to expansion tank through valve 1.

13
Pressure Distance 

sampling L, 

number mm 

11 2495 

"10 27 1AS 

4-- 9 2330

2185

H--- 6 1225

-II-- 5 505

_i .. 4 120 

4-IlL3 45

Fig. 2.5. Scheme of location of the thermocouples TWi-k and pressure sampling points along the 

FA model height.

14

Distance 

AL, 

nmm 

40 

145 

480 

480

720 

385 

75
Full draining of the UP model was made after heating-up of pipeline metal in the upper parts of the 

VVER Loop model up to saturation temperature under near values of pressure Pout (t0exp) and 

water temperature TFin (tOexp) at the core inlet to specified ones. Coolant collapsed level in the UP 

model was controlled with differential manometer DL13-12. Also it was set partially uncovering of 

the Core model using water drainage from the lower pipeline to expansion tank through the valve 2. 

Coolant collapsed level was controlled with differential manometers DL2-4 and DL4-14 in the DC 

model and with differential manometers in the Core model. 

After establishment of water temperature TFin (t0exp) and mixture level Lm (tO) in the Core model, 

main test for investigation of heat transfer in the partially uncovered FA was started. Due to 

condensation dominance (YQloss > W), in closed circulation circuit (valves 1,2 and 3 were closed) 

slow pressure Pout (t) decrease, slow mixture level Lm (t) increase and rod temperatures TW (t) 

variations were realized. Measurements of the TW-k (t) temperatures along the height of FA model 

with thermocouples on 20 elevations have provided temperature axial distribution in the FA model 

and test data about level of two-phase mixture in the FA channel with accuracy of ± 50 mm. 

Measurements, acquisition and registration of data were implemented in quasi-steady regime under 

constant FA power and water temperature TFin in the Lower Plenum model, and also under slow 

variations of pressure and mixture level in the Core model. The test has been carried out under initial 

conditions with pressure Pout (t0exp)=37.7 bar at the Core model outlet, water temperature TFin 

(tOexp)= 517 K in the Lower Plenum model, low mixture level Lm (t0exp) = 0.57 m in the Core 

channel and constant power W (t) = 9.52 kW of FA model. 

3.2. Initial and boundary conditions 

3.2.1. Boundary conditions at the outer surfaces of KS-1 VVER Loop model. Heat losses 

Only SG tube bundle simulator is non-heat-insulated part of experimental circuit. All other outer 

surfaces of the KS- 1 VVER Loop model have been covered by heat insulation. 

Measured ambient temperature during experiments was 27°C. 

Before the set of main experiment there were implemented preliminary experiments to determine 

heat losses from the VVER Loop model to environment and also heat balance in the Core model: 

electrical power of the FA model, single-phase (water) coolant heating and heat losses. 

Determination of total power of heat losses ZQloss (exp) from outer surfaces of the circuit to 

ambient air was made on the base of special experiment on boiling-condensing regime with natural 

circulation in the circuit during water boiling in full wetted FA model under constant pressure Pout

15
(t)=51 bar and, hence, with equality W=XQloss (exp). Total heat losses were equal to 50.2 kW. 

Accuracy of experimental determination of the total heat losses XQloss was ± 5%. However, for 

code modeling of determinative parameters behavior (heat release power W (t) of the FA model, 

pressure Pout (t), coolant temperature TFin (t) in the core inlet and mixture level Lm (t) in the core) 

in the other Test 35-1 with EQloss>W and, hence, with gradual decrease of pressure and saturation 

temperature Ts (P) in the circuit, adjustment of heat losses power XQloss (tcal) is needed. This value 

must be such, that calculated time history of pressure decrease Pout (tcal) coincides with 

experimental curve Pout (texp) as well as possible. Therefore, experimental value W (t)=50.2 kW 

for above mentioned special experiment is only first approach for determination of XQloss (tcal) 

during code modeling of other experiment. 

Distribution of heat losses on circulation circuit may essentially influence on calculation results. 

Value of heat losses and their distribution along circulation circuit determines rate of steam cooling 

and condensation, hence, flow rate of steam condensate, back flowing into the Core model and into 

the DC model. Theoretical calculations of the coefficients for heat transfer from outer surfaces of the 

pipes with different outer diameter Do to air were made on the base of data about geometry and 

thermal conductive coefficient for thermal insulation and, also, theoretical calculation of the 

coefficients for heat transfer from outer surfaces of heat insulation to air. It allows calculate relative 

distribution of the heat transfer coefficients Kloss for outer surfaces of different parts of 

experimental circuit. Estimated coefficients Kloss in the different parts of circuit are shown in Table 

3.1. 

Table 3.1 Estimated heat transfer coefficients Kloss (Do) for different parts of experimental circuit 

Part of Lower MCC UP, MCC DC model Pressure SG 

experimental pipeline model models tube vessel simulator 

circuit tube tubes 

Outer 

diameter Do, 28 75; 89 114 121 219 75 

mm 

Coefficient 

Kloss (Do), 5.6 3.2 3.2 3.4 2.8 5.9 

W/(m2.K)

16
All theoretical values of Kloss have to be multiplied by correctional coefficient Closs >1 for every 

particular experiment. It is explained by existence of air ventilation in the test facility compartment 

and also, presumably, by under estimation of thermal conductive coefficient of heat insulation in 

theoretical calculation of KMoss. 

Power Qloss (Do) of heat losses from outer surfaces (with areas Sout) of pipelines with different 

diameters, pressure vessel tube of the Core model, UP and DC models, through thermal insulation 

layer to ambient air is calculated from equation (1): 

Qloss (Do) = Closs M Moss (Do). Sout. (Tout - Tair). (1) 

Corresponding value of correctional coefficient Closs is adjusted that calculated and experimental 

curves of pressure decrease Pout (tcal) and Pout (texp) coincide as well as possible. 

3.2.2. Initial and boundary conditions inside of coolant circulation circuit 

Temperature regime of the heated rods in uncovered zone of the FA is directly coupled with coolant 

level dynamics in the core under boiling-condensing conditions. In this case level of two-phase 

mixture determines also steam mass flow rate in uncovered zone of the FA. Therefore adequate data 

about mixture level in the FA channel are required for calculation of the rod temperature regime. 

The FA model consists of rod simulators, which are made of identical stainless steel tubes with the 

same wall thickness. Therefore, during water boiling in full wetted FA model under uniform 

distribution of the wall temperatures TW the specific volumetric power qv and heat flux qw 

distribution in parallel rod simulators is uniform on radius and height of the FA model too. But, 

under conditions of the partially uncovering of the FA model, temperature axial and radial 

distributions become essentially non-uniform. Under direct electric heating of the rod simulators, 

local power at the various elevations of the FA model is determined by electric resistance of 

stainless steel tubes, which essentially increases with wall temperature raising. The influence of the 

rod resistance variation with temperature on radial and axial power distributions in the FA model 

may be taken into account using results of rod simulators temperature distribution measurements and 

reference data [ 1] about electric resistance of 12X 1 8H lOT steel at various temperatures. 

During the test coolant temperature was varied in relatively narrow range, so variations of heat 

conductivity and specific heat capacity of talkochlorite insulator in the Core model were negligible. 

However for modeling calculations, temperature dependencies of these parameters were used [2]. 

There are not heat losses inside of rod simulators, because they are closed in the top. 

Initial and boundary conditions for modeling quasi-steady regime are:

17
- DC model and Lower Plenum model have been filled up with water under defined temperature 

TFin (tOexp) and mixture level Lm (t0exp) in the Core model, and corresponding collapsed level in 

the DC model, pressure Pout (t0exp) and power W (tOexp) in the FA model; 

- the other parts of the circuit located above mixture level: Upper Plenum model, Hot Leg model, 

SG tube bundle and cold leg simulators and upper part of the Downcomer model have been filled up 

with saturated steam; 

- the water flow rate at the core inlet is determined by driving head under steam-condensate 

circulation conditions; 

- FA axial and radial distributions of wall temperature TWi-k (toexp) along the core height are 

determined in the test under slow pressure decrease due to ratio of the FA power W and total 

heat losses rate Qloss (W<Qloss). 

Time interval for TW (t) wall temperature stabilization in some rod simulators was Z 400 s. This 

time is not enough for full temperature stabilization of the talkchlorite insulator, steel shroud tube 

and pressure vessel tube having essentially greater thermal inertia than rod simulators with thin wall 

thickness. 

Non-steady heating of talkchlorite insulator and the steel shroud, steam in the Core model annular 

channel and, also, non-steady heating of Core model pressure vessel tube may be calculated, if 

specific densities, heat capacities and thermal conductivity coefficients of steel and talkchlorite are 

known [1, 2]. 

3.3. Experimental limitations and shortcomings 

One of experimental shortcomings is a technique difficulty of superheated steam temperature 

measurement at the FA model outlet, since steam condensate may occur at the thermocouple TFfa 

and disturb measurements. 

Temperature data about talkochlorite insulators and stainless steel shroud are absent. It makes 

difficulty for evaluation of heat flux from up-coming steam flow to these elements of the Core 

model during dynamic regimes. 

Impulse tubes of differential manometers are located in annular channel of the Core model filled 

with water and partly with steam. Temperatures of these tubes are not measured. 

3.4. Experimental Data used 

The report presents experimental data on the behavior of the rod simulators temperatures

18
TWi-k (texp), coolant temperatures TFin (texp), TFfa (texp), TFup (texp), pressure Pout (texp), 

pressure differences DL13-12, DL2-4, DL14-4, DL4-3, DL5-4, DL6-5, DL7-6, DL8-7, DL9-8, 

DLl 1-10 (texp) and mixture level Lm (texp) in the Core model with constant FA power W (texp)= 

9.52 kW for Test 35-1. Initial values of determinative parameters of Test 35-1 for quasi-steady 

regime are presented in Table 3.2. Original data plots from Test 35-lare presented in Figures A-l÷ 

A-15 in Appendix A. Complete set of experimental data obtained at the experimental section KS- 1 

is in RRC KI report [3]. 

Table 3.2. Initial values of determinative parameters of KS-I Test 35-1 for quasi-steady regime 

Experiment Power Pressure Mixture level Temperature 

W(t0exp), Pout(tOexp), Lm(t0exp), TFin(t0exp), 

kW bar m K

To simulate experimental initial conditions using RELAP5/Mod3.2, it is necessary to know real 

mixture level Lm (t0exp) in the Core model at the initial moment t0exp. Therefore, in Table 3.2 

initial mixture level Lm (t0exp) is presented. Real mixture level was determined on the base of 

preliminary analysis of behavior of rod simulator temperatures and of core axial distribution of rod 

temperatures TWi-k (tOexp) along the height of heated zone at the initial moment t0exp. 

KS1-Test 35-1 characteristics 

During quasi-steady regime with constant FA model power W (t) = 9.52 kW (see Fig. A-i), slow 

pressure decrease took place with rate dPout / dt = 0.016 bar/s (see Fig. A-2). It was realized in 

closed circulation circuit for enclosed valves 1, 2 and 3 under steam-condensate circulation 

conditions. Initial value of pressure was Pout (t0exp)=37.7 bar. Pressure value at the moment 

tlexp=100 s was Pout (tlexp=100 s)=36.1 bar. This pressure decrease occurred due to predominance 

of steam condensation in the circuit over steam generation in the Core model (EQloss>W). Due to 

predominance of condensate flow down rate over coolant boiling-off, very slow increase of 

collapsed level in the DC model during experiment took place (see curve DL4-14 (t) in Fig. A-5). 

Due to this predominance and also due to pressure decrease, very slow increase of mixture level in 

the core channel took place with rate dLm / dt = 0.22 mm/s. Initial value of mixture level was Lm 

(tOexp)=0.57 m. There is slow increase of rod simulators temperature TW (t) in uncovered part of 

the FA model at the level of 2.48 m with rate dTW / dt = 0.14 K/s (see curve TW06-00 (t) in Fig. A

7). Wall temperatures of rod simulators in FA cross sections, located above mixture level, were 

19

KS1-35-1 9.52 -37.7 0.57- 517
practically constant during experimental time 0-100 s (see Fig. A-14). 

Initial value of water temperature at the inlet of the Core model was TFin (tOexp)= 517 K, then one 

very slow decreased down to TFin= 515 K during experimental time 0-100 s (see Fig. A-3). 

Essentially non-uniform FA model axial and radial distribution of rod simulator temperatures TW 

was obtained during FA cooling under conditions with CCF in Core model channel. Measured 

maximal values of rod simulators temperatures TW (t) max were realized in the middle part of the 

FA model (elevation is 1.525 m) in a middle row of rods (see curve TW07-10 in Fig. A- 11). 

Presented above characteristics of chosen experiment show, that pressure Pout (t), coolant 

temperature TFin (t), mixture level Lm (t), rods temperatures TW (t) and their core axial distribution 

relatively slow vary in quasi-steady regime. Furthermore, there is such cross section of the FA 

model, that practically TW (t) temperature steady regime occurs for long time interval. This time 

interval essentially exceed time, which is necessary for stabilization of wall temperature of rod 

simulators, which have relatively small wall mass and heat capacity in comparison with large wall 

masses and heat capacities of talkochlorite insulators and steel shroud tube and pressure vessel tube. 

Experimental initial values at the moment tOexp and behavior of determinative parameters for quasi

steady state, having to be adequate provided during code simulation, are listed below: 

- Constant power of heat release in the FA model W(t)=9.52 kW; 

- Pressure at the core outlet Pout (tOexp)=37.7 bar; 

- Slow pressure decrease down to Pout (texp=100s)=36.1 bar with rate dP/dt =0.016 bar/s; 

- Coolant temperature at the Core model inlet TFin (tOexp)- 517 K; 

- Mixture level location in the core model Lm(tOexp)=0.57 m; 

- Slow level increase with rate dLm/dt = 0.22 mm/s; 

- Distribution of steam void fractions above mixture level on the length of NC circuit and on 

steam release pipeline from point A to closed valve 1, and also on the height of the FA channel 

and annular channel, which are equal 1.0; 

- Distribution of average temperature of water and steam on length of NC circuit and on steam 

release pipeline from point A to closed valve 1; 

- Distribution of average (averaged on wall's thickness) wall's temperatures of pipelines, pressure 

vessel and internal parts of circuit (UP, MCC, DC, SG and steam release pipeline from point A 

to valve 1); 

- Distribution of average wall's temperatures of rod simulators on the height of the FA model, 

which are superheated above Ts temperature in uncovered part under Pout (tOexp);

20
Distribution of average wall's temperatures of steel shroud, talkochlorite bushes and pressure 

vessel on the height of the Core model, which are Ts temperature under Pout (tOcal); 

Distribution of average temperatures of water in the LP and DC models under mixture level and 

in the lower pipeline, which are equal TFin (tOexp) temperature; 

Distribution of average wall's temperatures of the lower pipeline, which are equal TFin (tOexp) 

temperature; 

- Distribution of power of heat losses Qloss (tOexp) from outer surfaces of the circuit to ambient 

air with constant temperature of 27 'C; heat losses is determined by particular heat transfer 

coefficient Moss and adjusted correctional coefficient Closs (tOexp)=3.0 (see equation (1). 

4. DESCRIPTION OF RELEASED CODE VERSION AND BASE CASE INPUT DECKS 

4.1. Code Description 

The code used for this work was RELAP5/MOD3.2 (Frozen version) [4, 5], with no further updates. 

This code was used for the Nodalization study and the base case calculations. The code has been 

installed on the IBM PC AT Pentium- 166 computer with Windows 95 operating system and 

Watcom translator. 

4.2. Input Deck Development 

Figure 4.1 shows the nodalization to simulate the KS-1VVER Loop model and Test 35-1 with 

RELAP5/MOD3.2. The code modeling of the test followed the specific calculation procedures used 

for simulation of the experimental initial and boundary conditions. 

The RELAP5/MOD3.2 model consists of all parts of the primary circuit of the KS-1 experimental 

section, in total of 1 IRELAP5 components with 198 hydrodynamic Volumes, 198 Junctions and 217 

Heat Structures with 982 mesh points. A complete listing of the base case input set is listed in 

Appendix D. 

Nodalization scheme for KS-1 VVER Loop model includes the following components of the 

primary circuit: - Lower plenum model (v. 21, sj 22, v. 23), Core model (sj 24, v. 5, sj 25, v. 7, sj 8), 

Upper Plenum model (v. 9, sj 10, v. 11), Hot Leg model and SG tubes simulator (sj 12, v. 14), Cold 

Leg simulator and SG tubes simulator (v. 106), Downcomer model (sj 101, v. 102, sj 103, v. 104) 

and Lower Water pipeline (v. 1, sj 2). All external solid components were specified in the input 

model to account for heat losses into the environment air. Hydrodynamic components and heat 

structures geometry data were taken from the RRC KI report [3].

21
A "pipe" hydrodynamic component Lower Water Communication Line 1 (sv. 101 - sv. 169) 

represents the test Lower Water pipeline fluid volumes with initial water temperature TFin (t0exp). 

A "pipe" hydrodynamic component Core Channel 7 (sv. 701 - sv. 721), representing the test core 

channel fluid volumes, is connected to Lower Plenum model 23 at the bottom and to Upper Plenum 

model 9 at the top by the Single Junctions (SJ 25, SJ 8). 

Volumes from 701 to 720 represent the part of the core channel with the heated bundle. The 

different nodalization were selected and tested using 10 and 20 volumes for the bundle by fixing the 

number of fine mesh nodes in the heat conduction elements. Here the core nodding pitch was chosen 

equal one or half spacer grid pitch (250 or 125 mm). 

An "annulus" hydrodynamic component 5, representing annular channel in Core model, is connected 

with the Lower Plenum model 21 at the bottom by the Single Junction (SJ 24) and filled with 

saturated or superheated steam. 

A "pipe" hydrodynamic components Upper Plenum 9, 11 (sv. 901- sv. 903, sv. 1101 - sv. 1111), 

representing the test UP fluid volumes, is connected to Core Channel at the bottom and to Hot Leg at 

the top by the Single Junction (SJ 12). 

A "pipe" hydrodynamic component Hot Leg, SG, Steam Pipe 14 (sv. 1401 - sv. 1414), representing 

the test HL, SG and Steam pipe fluid volumes, is connected to UP at the bottom and to SG 106 at 

1407 sub-volume side by Single Junction (SJ 107). 

A "pipe" hydrodynamic components SG tubes simulator 106, Cold Leg simulator 104 and 106, 

Downcomer model 102, 104 and Lower Water pipeline 1 represent the test CL, SG and DC fluid 

volumes. 

Heat structure scheme used to describe power distribution of the FA heated tube bundle and circuit 

heat losses into environment is shown in Figure 4.1. 

In the analysis of the test the counter current flow limitation (CCFL) flag (f=l) was used with the 

Single Junction 22, representing local cross flow area decrease inside the Lower Plenum between v. 

21 and v. 23. The default values of the four quantities Dj, 3=0, c=1 and m=l were used. Wallis 

CCFL model was used to correct modeling behavior of mixture level in the core channel with FA 

model under conditions of counter current flow.

22
Hot Leg

SJ12

Upper 

Plenum 

Qloss

Lower 

Plenum

- 10 SJ107 

s 1Steam Generator _104 

Cold Leg 

03 03 02 - 01 

Downcomer 

E Control volume 

Z Heat structure of steel tube 

_ Heat structure of talkochlorite bush 

SJ -Single Junction 

101

Water Line

Fig. 4.1. Base case nodalization scheme for RELAP5/3.2 modeling of KS-I Test.

23
CCFL model was not activated in the core channel with FA model. In the code calculations of 

processes in the core with the bundle for the interphase friction were used the correlation developed 

for rod bundles. To activate convective boundary conditions for non-standard geometry when 

modeling a vertical bundle, the rod pitch-to-diameter ratio was input. 

4.3. Determinative and determined parameters for code simulation of the experimental 

conditions and analysis of investigated processes/phenomena 

Mixture level location determines power portion for steam generation in covered part of FA and 

accordingly flow rate of saturated steam at inlet of uncovered FA part and power portion in 

uncovered FA part. Power portion in uncovered FA part determines heat-up and distributions of 

steam flow temperatures and rod simulator temperatures along the height of FA uncovered part. 

Thus, it is necessary to have accurate data about initial location of mixture level Lm (tOexp) and its 

behavior during experiment to calculate rod temperature distribution along the core height. 

In dry out zone it is possible local power excess over heat transfer from rod surface to steam flow. 

As a result, local wall temperature will increase with some rate dTW/dt, which depends on 

mentioned above power excess and on heat capacity of the rod simulator part. In other case, local 

cooling of rod simulator part is possible. Hereof, rate of temperature variation of rod simulator wall, 

during local heating or local cooling with certain local power and known heat capacity, is one of the 

main determined parameters of heat transfer in partly uncovered zone. This rate and absolute value 

of wall temperature TW characterize heat transfer in the considered part of core. 

Local value of rod wall temperature is determined by local temperature of steam flow and by local 

temperature difference between steam and rod wall. This difference is determined by local heat flux 

value and by heat transfer coefficient. 

Temperature distribution of steam flow along core height depends on steam mass flow rate, intensity 

of heat transfer of steam with rod walls and talkochlorite insulator surfaces, and also it depends on 

intensity of interphase heat transfer under CCF of generated steam and steam condensate. 

Heat flux qw2 (t) from steam to insulator and its stabilization time, and also temperature regime of 

inner wall of insulator TWi (t) are determined by intensity of heat transfer: - between coolant and 

talkochlorite insulator, between steel shroud and inner wall of pressure vessel tube through annular 

gap and between outer surface of pressure vessel and ambient air. Heat flux qw2 (t) and its 

stabilization time also depend on thermal conductivity coefficients and relatively large heat 

capacities of considered massive parts of the Core model.

24
Thus, quality of the code modeling for rod temperature behavior in uncovered zone of FA model 

depends on both accurate simulation of hydrodynamic processes in the circuit and also accurate 

simulation of processes heat transfer from rod simulators to coolant flow and, further, to 

environment. 

Therefore, it is necessary to provide close coincidence of calculated and experimental values of 

pressure Pout (tcal) and Pout (texp), mixture level location Lm (tcal) and Lm (texp) in the core 

channel, coolant temperature at the core inlet TFin (tcal) and TFin (texp) and steam generation rate 

for adequate simulation of heat transfer in partially uncovered FA model. Also it is important to take 

into account complex processes of heat transfer on rod surfaces under CCF conditions, interphase 

heat transfer and heat transfer from superheated steam flow into environment. 

The following determinative parameters (which initial values and behavior are defined in the 

experiment) have to be adequate provided in code simulation using specified boundary conditions: 

- Behavior of heat release power in the FA model W (t), 

- Initial value of pressure at the Core model outlet Pout (tOexp), 

- Initial value of coolant temperature at the Core model inlet TFin (tOexp), 

- Initial distribution of average void fractions on the length of NC circuit and steam release 

pipeline from point A to closed valve 1, and also on the height of the FA channel and annular 

channel, 

- Initial distribution of average temperatures of vapor and liquid on the length of NC circuit and 

steam release pipeline from point A to closed valve 1, 

- Initial distribution of averaged on wall thickness wall's temperatures of pipelines, pressure 

vessel tube and others, which determine accumulated heat in the circuit elements, 

- Initial distribution of average wall's temperatures of rod simulators and inside parts of the Core 

model (steel shroud with talkochlorite bushes), 

- Power of heat loss EQloss (t) from outer surfaces of the circuit to ambient air. Heat losses power 

is determined by particular heat transfer coefficients Kloss and adjusted correctional coefficient 

Closs (see equation (1)). 

All of mentioned above parameters govern further behavior of following determined parameters: 

- Pressure at the Core model outlet Pout (tcal), 

- Coolant temperature at the Core model inlet TFin (tcal), 

- Mixture level in the core channel Lm (tcal), 

- Mixture level in the DC model DL4-14 (tcal) and DL2-4 (tcal),

25
- Total pressure difference DPt (tcal) on the height of the core model and DP13-12 (tcal) on the 

height of UP and DL4-14 (tcal) on the height of DC model, 

- Flow rate of coolant at the Core model inlet GL in (tcal) under NC conditions, 

- Flow rate of steam condensate GL out (tcal ), flowing down from circuit elements to the Core 

model outlet 

- Flow rate of steam condensate GL in (tcal), flowing down from circuit elements to the DC and 

then to the Core model inlet, 

- Distribution of steam flow rate Gg (tcal) on the height of uncovered part of the FA model, 

Distribution of steam velocity Vg (tcal) on the height of uncovered part of the FA model, 

- Distribution of steam temperature Tg (tcal) on the height of uncovered part of the FA model, 

- Distribution of water flow rate GL (tcal) on the height of uncovered part of the FA model, 

- Distribution of water velocity VL (tcal) on the height of uncovered part of the FA model, 

- Distribution of water temperature TF (tcal) on the height of uncovered part of the FA model, 

- Distribution of temperatures of inner surfaces of rod simulators TWi-k (tcal) in different levels k 

on the height of FA model; rates dTW/dt, 

- Distribution of coefficient Hwl (tcal) of heat transfer from outer surfaces of rod simulators to 

coolant on the height of FA model, 

- Distribution of coefficient Hg2 (tcal) of heat transfer from coolant flow to the talkochlorite 

insulator on the height of FA model, 

- Distribution of coefficient Hw3 (tcal) of heat transfer from outer surface of steel shroud to 

coolant on the height of annular channel, 

- Distribution of coefficient Hg4 (tcal) of heat transfer from coolant to inner surface of the 

pressure vessel tube on the height of annular channel, 

- Distribution of specific heat flux qwl (tcal) from outer surfaces of the rod simulators to coolant 

on height of FA model, 

- Distribution of specific heat flux qw2 (tcal) from coolant flow to the talkochlorite insulator on 

height of FA model, 

Distribution of specific heat flux qw3 (tcal) from outer surface of steel shroud to coolant on the 

height of annular channel, 

Distribution of specific heat flux qw4 (tcal) from coolant to inner surface of the pressure vessel 

tube on the height of annular channel, 

Distribution of specific heat flux qwioss (tcal) from outer surface of pressure vessel to ambient air.

26
Location of mixture level Lm (t 1 cal) = Lm (tOexp) in the core channel and its behavior Lm (tcal) are 

determined by special analysis of calculation results and experimental data about temperatures TWi

k (t) of inner walls of rod simulators and their height distributions and temperature change rates 

dTW/dt. In this case the following assumption is used. Real mixture level is that level in the core 

channel, at which sharp increase of void fraction and local dry out of rod simulators take place. And 

then a sharp decrease of heat transfer coefficient Hwl (t), specific heat flux qwl (t) from outer 

surfaces of rods to coolant and local increase of temperatures TW (t) of rod simulators above 

saturation temperature take place also. 

Results of comparison of calculated and experimental values of mentioned determinative and 

determined parameters are a base for conclusion about adequacy of the code simulation of initial and 

boundary conditions, realizing in experiment at the initial moment t0exp, and then about adequacy 

of simulation of quasi-steady regime of whole experiment. 

4.4. Method of code simulation of initial and boundary conditions with RELAP5/MOD3.2 

Goals and method of implementation of KS-lexperiments in 1991, and also way of the results 

treatment to obtain dependence of heat transfer coefficient Hwl on steam flow rate under conditions 

with known pressure and mixture level in the Core model do not stipulate the achievement of 

completely steady state in all components of the circuit. Furthermore, steady state is impossible 

under conditions of slow decrease of pressure due to heat loss predominance and partially 

uncovering of the Core model. In particular, it is impossible to obtain simultaneously stationary 

temperature regime of rod simulators and talkochlorite insulator, of the shroud and pressure vessel at 

different elevations of uncovered part of the FA model under achievement of allowable rod 

simulator temperatures. It is explained both by slow variation of hydrodynamic parameters and 

different heat capacity and thermal conductivity for the Core model elements. 

Therefore, these experimental data are considered ones, obtained in quasi-steady regime under 

constant FA power W (t) and relatively slow variations of determinative parameters. Probably, in 

certain stages of the process, it is possible to consider regimes of heat transfer to the massive parts of 

the test facility in partially uncovered Core model as stable ones with constant heat transfer 

coefficients. 

During definition of the assessment problem main attention has been paid on evaluation of 

RELAP5/MOD3.2 adequacy to simulate separate phenomena/processes of heat exchange under low 

mixture level, middle pressure and small FA model power. Simulations of hydrodynamic

27
phenomena in main circuit parts, presumably, have to be considered as auxiliary tasks. Solution of 

these tasks is necessary to provide required initial and boundary conditions in partially uncovered 

Core model. 

This approach is governed by fact, that essential uncertainties may occur during code simulation of 

such hydrodynamic parameters as mixture level location, void fraction distribution, CCF liquid and 

vapor mass flow rate distribution and interphase heat transfer along the height of uncovered part of 

FA. Special analyses of code adequacy for simulation of reflux condenser mode in closed circuit 

need to be additionally implemented. Therefore, to diminish probable influence of these 

uncertainties on calculation results for heat transfer coefficients and rod's wall temperatures 

distribution, it is necessary to develop special method of code simulation of adequate initial and 

boundary conditions in partially uncovered Core model. 

RELAP5/MOD3.2 code simulation requires definition of certain steady state with known boundary 

conditions at the time tOcal. Starting with this point and using certain transition procedures, it is 

possible to achieve such quasi-steady state, that one most adequate describes a state of circuit and 

Core model in the experiment at the initial moment tOexp. 

It should be taken into account that code simulation of auxiliary problems concerning of transient 

hydrodynamic processes in the circuit parts and in the whole circuit can lead to essential 

inaccuracies of calculated parameters both under steam-condensate circulation (reflux condenser 

mode) and, especially, under down flow of steam-water mixture. This fact can take place in the case 

of modeling of experimental procedure of coolant drainage from lower pipeline through the valve 2 

for partially uncovering of the FA model and establishment of needed mixture level. Experimental 

scenario of water drainage from the circuit through the valve 2 was very complicated for particular 

experiment. It is very difficult for code simulation. Evidently, seeming coincidence of simulation 

method for coolant drainage calculation procedures with experimental procedures does not provided 

simplicity of selection of necessary flow rate of drained water, drainage duration, initial pressure 

Pout (tOcal), initial coolant temperature TFin (tOcal) and also values of correctional coefficients 

Closs (t). 

Skilled modeling user can propose several different methods and simplified procedures for code 

simulation of initial and boundary conditions of KS-1 Test 35-1. For example, first variant of such 

method may be as following. At the first step, for code simulation of the experiment, simple initial 

steady state may be defined. This state is characterized by full separation of certain amounts of 

saturated steam Mg and liquid ML in the FA channel, in the Core model annular channel, in the

28
Lower Plenum model and DC model. It is realized under constant initial pressure Pout (tOcal >Pout 

(tOexp), zero FA heat release and zero heat losses {W (t0cal)=0, Closs (t0cal)=0} during certain time 

interval tcal-0-100 sec, for example. During calculation of this quasi-steady state, correction of 

probable inaccuracy of definition of collapsed level and stabilization of temperatures of coolant and 

temperatures of metal parts take place. 

At the second step, transition to a quasi-steady state at the moment tl cal is carried out. This state has 

to be the closest one to experimental conditions at the moment t0exp. 

Mentioned above transition may be done by following smooth and parallel in time procedures: 

- Linear increase of heat release power in the FA model with certain rate dW/dt up to experimental 

value W (tcal) = W (t0exp). It is necessary for providing of required power and mixture level 

location; 

- Increase of heat losses power by definition of certain law (may be linear) of increase of 

correctional coefficient Closs (tcal) up to required value Closs (tcal) to provide the best 

coincidence of calculated curve Pout (t)cal with experimental one Pout (t)exp. 

For this method variant, curves of possible variations of regime parameters (FA model power W 

(tcal), correctional coefficient Closs (tcal), pressure Pout (tcal), coolant mass inventory M=ML+Mg, 

full pressure difference on the core model DPt (tcal) and, accordingly, level location Lm (tcal), and 

also flow rate of generated steam Gg out (tcal) at the Core model outlet and flow rate of steam 

condensate GL out (tcal) flowing down to the Core model are shown on Fig.4.2 - 4.5. 

In this case, it is possible to adjust mixture level location by selection of liquid mass and value of 

initial pressure Pout (tOcal). Coordination of calculation time interval (tlcal - t2cal) for required 

variation of pressure from Pout (tlcal)=Pout (tOexp) to Pout (t2cal)=Pout (tlexp) with calculation 

time interval for required variation of mixture level from Lm (tlcal)=Lm (tOexp) up to Lm 

(t2cal)=Lm (tlexp) and with time of experiment realization Dtexp=(tlexp - t0exp) is possible by 

means of selection initial values for liquid mass inventory ML (tOcal) , pressure Pout (tOcal) and for 

correctional coefficient Closs (tcal). 

To simplify development of special method of code simulation of initial and boundary conditions for 

the experiment, preliminary analysis of interdependent thermal and hydraulic processes in KS -1 

Test 35-1 was made. This analysis was carried out with RELAP5/MOD3.2 code in frame of the first 

method of simulation of initial and boundary conditions. 

Experimental initial values at the moment t0exp and behavior of determinative parameters for quasi

steady state, having to be adequate provided during code simulation, are listed in Section 3.4.

29
'(Si-35 LkD2/M - 003.2

-4

0

Fig. 4.2. Variation of FA Model power W(t), correctional coefficient of heat losses Closs(t) 

and coolant mass inventory M=ML+Mg in the closed loop during calculation procedures for 

modeling of KS-1 Test (tcal=0-600 s).

t0expl I zxp

IUU ZUU 3UU 4UU 

Time (s)

SUo

PR: AP/\AcThTh9

bLU

Fig. 4.3. Comparison of RELAP5/MOD3.2-calculated Pout(t)cal (tcal=0-700 s) and experimental 

Pout(t)exp curves of pressure decrease, and also selection of time interval, corresponding Dtexp, and 

selection of time moment t I cal, corresponding tOexp for KS-I Test.

31

45.0

40.0 

35.0 

30.0 

25.0 

i-p 

S20.0 

15.0 

10.0 

5.0 

0.0

U

KS1 -55- !

X'Ri -. %5--1

/00^
tlcci I 

tOexp•

2O0 300 400 

Tine (s)

t2,o 

tlexp

500 600 700

Fig. 4.4. RELAP5/MOD3.2-calculated Dpt(t) Core Model total differential pressure, DPu(t), 

core upper half part differential pressure and DPb (t) core bottom half part differential pressure 

histories, and also selection of time interval, corresponding Dtexp, and selection of time moment 

tl cal, corresponding tOexp for KS-1 Test (tcal=0-600 s).

KSi-35-1 RFI AP5/MV.3.-Th 2

,~ I 

Lr 

L ~t2ýcý I' z~ j- Gc ,mass f!ow / 

t~~Oexp!It~ x 

1 . . . ! . ." . . [ 2

. . . . . . . . i . .. . . .. . . . ' 0 100 20c 300 LOC Ti''e (s)

5 C 600 7CC

Fig. 4.5. RELAP5/MOD3.2- calculated Ggl(t) mass flow rate of generated steam and GLI(t) steam 

condensate mass flow rate histories under CCF conditions at Core Model outlet (tcal-0-600 s), and 

also selection of time interval, corresponding Dtexp, and selection of time moment t1cal, 

corresponding tOexp for KS-I Test.

32

C 

0 

C 

C 

C 

C 

0 

0

-40CC o 100

-01 0

0.005 

0.0OC

C 

C

:2 

C 

C 

C

--0.005
Description of base steady state at the moment tOcal, initial and boundary conditions at this moment 

and also possible code procedures and features of transient to quasi-steady state for first method is 

presented below. 

During code simulation of KS-1 Test 35-1 with RELAP5/MOD3.2 we defined simple initial and 

boundary conditions of the base steady state at the moment tOcal. Starting from this state and using 

procedures of the first transition method, it is possible to transit to required quasi-steady state at the 

moment tl cal, which is adequate to experimental state at the moment t0exp. 

Taking into account our preliminary analysis of this experiment, following initial and boundary 

conditions for base steady state at the calculation moment tOcal may be set up with W (t0cal)=0 and 

Closs (tOcal)=0: 

- initial pressure Pout(t0cal)= 42 bar, which is greater than Pout (tOexp)=37.7 bar; 

- model of Downcomer, model of Lower Plenum and also lower pipeline are filled with water with 

temperature TFin(tOcal)=TFin(tOexp); water level in the core channel and the DC model are 

special selected for subsequent coincidence of calculated level Lm(tlcal) with experimental one 

Lm(tOexp); 

- remaining part of circuit, namely, UP model, BL model, SG simulator, CL simulator, upper part 

of DC model and also steam release pipeline, are filled with saturated steam with initial pressure 

Pout(tOcal)>Pout(tOexp); 

- temperatures of steel shroud, talkochlorite insulator in the Core model, rod simulators, pressure 

vessel tube, tubes of the UP and MCC model, tube and talkochlorite bushes of upper part of the 

DC model (above water level) are equal saturation temperature for Pout(t0cal). 

During calculation from tOcal=100 s (without heat power in FA and without heat losses under W 

(t0cal)=0 and Closs (t0cal)=0) , correction of inaccuracies and stabilization occur for collapsed 

levels in FA channel, in annular channel and DC model under constant total mass inventory of liquid 

and vapor in the circuit M=Mg+ML. 

After calculation of quasi-steady state during tcal = 0-100 s, it is possible to transit from quasi-steady 

state at the moment tcal=100 s to required quasi-steady state at the moment tlcal=365 sec, which 

closely corresponds to experimental quasi-steady state at the moment tOexp. Following smooth and 

parallel in time procedures may do this transition: 

- Linear increase of heat release power from zero to W=9.52 kW at the moment tcal=200 sec; then 

power is maintained constant to provide necessary heat release for modeling of smooth 

development of boiling process and steam generation process in the Core model and for setting

33
of required mixture level and steam generation rate; 

Smooth increase of heat losses power from particular parts of the circuit by determination of 

linear raise of correctional coefficient Closs (t) from zero at the moment tcal=100 sec to Closs (t)= 

3.0 at the moment tcal=200 sec; then this value is held constant. It provides the best coincidence of 

calculated Pout (tcal) and experimental Pout (texp) curves, development of steam-condensate 

circulation and establishment of specified flow rates of steam condensate in the FA model from the 

bottom and the top. 

Code simulation of calculation procedures for setting up initial and boundary conditions in the base 

steady state, and further transition to the quasi-steady state of KS-iTest 35-1 were realized during 

tcal=0 - 600 s. 

Calculation results of code simulation of KS-1 Test 35-1 initial and boundary conditions are 

presented on Fig.4.2. - 4.7. These figures show heat release power W (tcal), correctional coefficient 

Closs (tcal), pressure Pout (tcal), total pressure difference DPt (tcal) in the Core model, flow rate of 

generated steam Gg out (tcal) at the core outlet, flow rate of steam condensate GL out (tcal) flowing 

down to the core channel. These parameters are shown under realization of calculation procedures of 

transition from base steady state at the moment tOcal to quasi-steady state at the moment tlcal, 

which corresponds to experimental conditions at the moment t0exp for "quasi-steady regime". As 

may see, behaviors of determinative and determinate parameters during time interval t1cal - t2cal 

closely correspond to their variations in the experiment during time interval t=(t0exp+Dtexp), where 

Dtexp= 100 s is time of experiment realization. 

Location of mixture level Lm (tlcal) = Lm (t0exp) in the core channel and its behavior Lm (tcal) are 

determined by analysis of calculation results and experimental data about temperatures TWi-k (t) of 

inner walls of rod simulators and their height distributions and temperature change rates dTW/dt. 

RELAP5/MOD3.2-calculated TW (t) heated tube inside wall temperatures histories in the upper, 

middle and bottom parts of the FA model (tcal=0-600 s), and also selection of time interval, 

corresponding Dtexp, and selection of time moment tlcal, corresponding t0exp for KS-lTest 35-1 

are shown in Fig. 4.6. There is slow increase of mixture level in core channel and decrease of rod 

simulators temperature TW (t) in covered bottom part of the FA model at the levels equal 0.0 - 0.562 

m (see curves TW (tcal) for heat structures 0071001 - 0071005 in Fig. 4.6).

34
':2 

a-

50 

]

KS1 -35-1

GESB- 0071001

007.004 -- 007 005 

4 ~007 006 z50 0 0 I 

550 

450.. . . exti P

RELAP5/MOD3.2

Tme (s)

Fig. 4.6. RELAP5/MOD3.2-calculated TW(t) heated tube inside wall temperatures histories in the 

upper, middle and bottom parts of the FA Model (tcal=0-600 s), and also selection of time interval, 

corresponding Dtexp, and selection of time moment ti cal, corresponding tOexp for KS- I Test.

35

0 1 200 51UC 6O 0 /©0
KSi-35-i1

TW-09-! ' .-"V 19-18 .- __-iC0071008 _0071007 

40 

texp

60 

time (s)

80 100

KSI -35-!

40 60 

:exp time (s)

0C

Fig. 4.7. Comparison of measured and RELAP5/MOD3.2-calculated heated tube inside wall 

temperatures histories in the bottom part of FA Model and also selection of time interval, 

corresponding Dtexp, and selection of time moment t I cal, corresponding tOexp for KS-I Test.

36

-0_ 

0 

E 

C)

550 

450

20

C) 

E 

0

850

.J

0
Wall temperatures of rod simulators in FA cross sections, located above mixture level, were 

practically constant during experimental time 0-100 s (see curve TW (tcal) for heat structure 

0071006 in Fig. 4.6, 4.7). Comparison of measured and RELAP5/MOD3.2-calculated heated tube 

inside wall temperatures histories in the bottom part of FA model, and also selection of time 

interval, corresponding Dtexp, and selection of time moment t I cal, corresponding t0exp for the test, 

are shown in Fig. 4.7. 

In this case, we used possibility to adjust mixture level location by variation of liquid mass inventory 

and value of initial pressure Pout (tOcal). 

Adjustment of calculation time interval (tlcal - t2cal) for required variation of pressure from Pout 

(tlcal)=Pout (tOexp) to Pout (t2cal)=Pout (tlexp) with calculation time interval for required 

variation of mixture level from Lm (tlcal)=Lm (t0exp) up to Lm (t2cal)=Lm (tlexp) and with time 

of experiment realization from t0exp till tlexp was done by means of selection of initial values for 

liquid mass inventory ML (tOcal), pressure Pout (tOcal) and correctional coefficient Closs (tcal). 

All mentioned above parameters determine subsequent behavior of determined parameters in the 

experiment. 

5. RESULTS 

5.1. Nodalization, including variations from base case 

Before choosing a final model, the effect of different nodalization to the results of 

RELAP5/MOD3.2 calculations was investigated for KS- I Test 35-1. Of interest was the influence of 

the number of hydraulic volumes chosen. The different nodalizations were studied using 10 and 20 

volumes for the core channel (hydrodynamic component 7) with heated bundle of FA model and for 

the Core model annular channel ("annulus" hydrodynamic component 5) by fixing the number of 

fine mesh nodes in the heat conduction elements. Here the core nodding pitch was chosen equal one 

or half spacer grid pitch (250 or 125 mm). As quality of the code modeling for rod temperature 

behavior in partially uncovered FA depends on accurate simulation of mixture level in the core 

channel, it is necessary to provide close coincidence of Lm (tcal) calculated and Lm (texp) 

experimental values of mixture level. Also it is important when complex processes of heat transfer 

on rod surfaces under CCF conditions and interphase heat transfer are simulated. 

Higher number of volumes results in more accurate code simulation of mixture level in the core 

channel. And, also, higher number of volumes results in smaller error (± 62.5 mm), when real

37
mixture level Lm (tlcal) = Lm (tOexp) and its behavior Lm (tcal) are determined by special analysis 

of calculation results for TW (tcal) and experimental data about rod simulator temperatures Twi-k 

(t). Measurements of the TWik (t) temperatures along the height of FA model with thermocouples 

on 20 elevations have provided temperature axial distribution in the FA model and test data about 

mixture level in the FA channel with accuracy of± 50 mm. 

All the calculations to be presented latter in this report were performed by selecting the nodalization 

with 20 volumes for the core channel with heated bundle as the base case (Fig. 4.1). 

5.2. Base Case Results of calculations, Comparison to KS-1 Test 35-1 and Conclusions 

Using nodalization scheme mentioned above, base case calculations were performed for KS- 1 Test 

35-1 using maximum user-specified time step dt max = 0.01 s, which was suggested in [5], 

concerning the use of the code reflood model. Code simulation of the procedures was realized during 

the time interval tcal= 0 - 365 s for modeling initial and boundary conditions in the quasi-steady 

state at the moment tlcal=365 s. Then further simulation of transient for "test quasi-steady regime" 

was realized during the time interval tcal= 365 -465 s. Further calculation ran till 600 s. 

Calculated histories of determinative and determinate parameters under calculation procedures are 

shown in Figures to examine hydrodynamic interactions between adjacent components and 

conditions for heat transfer in The Core model with FA during "quasi-steady regime" in the test. 

Additional code results are shown in Figures B-I+B-17 in Appendix B. The results give also the 

indications for activation the code models for modeling counter current flow limitation and 

interphase heat transfer. 

These Figures show behavior of determinative parameters under calculation procedures for transient 

from base steady state at the moment tOcal to quasi-steady state at the moment tlcal=365 s, which 

corresponds to experimental initial and boundary conditions at the test moment t0exp=0 s. 

As may see, behaviors of determinative parameters during time interval from t1cal=365 s till 

t2cal=465 s closely correspond to their variations in the experiment during time interval from 

t0exp=o s till tlexp=100 s. It is a base for conclusion about adequacy of the code simulation of 

initial and boundary conditions for hydrodynamics, realized in the experiment, and then about 

adequacy of simulation of "quasi-steady regime" of whole experiment. 

Comparison of RELAP5/MOD3.2-calculated Pout (tcal) and experimental Pout (texp) curves of 

pressure decrease, and also selection of time interval, corresponding Dtexp, and selection of time 

moment t 1 cal, corresponding t0exp are shown in Fig. B -1. Comparison of measured and calculated

38
pressure during time interval, corresponding texp=0- 100 s, illustrates good coincidence of the curves 

under test conditions with Closs (tcal) =3.0 (see Fig. B-2). It provides also setting up certain flow 

rate GL out (tcal)• 0.0022 kg/s of steam condensate down flowing to the core channel (see Fig. 4.5) 

when mass flow rate of generated steam at FA outlet Gg out (tcal)L 0.004 kg/s. 

Comparison of measured and calculated TFin (tcal) coolant temperature at Core model inlet is 

shown in Fig. B-3. The results are in a good agreement with test data. It provides needed mass flow 

rate of generated steam under test conditions with known pressure and mixture level in the FA 

channel. Initial mixture level Lm (tlcal) = Lm (tOexp) in the FA channel and its behavior Lm (tcal) 

are determined by analysis of calculation results and experimental data about temperatures TWi-k (t) 

of inner walls of rod simulators and their height distributions and temperature change rates dTW/dt. 

Calculated TW (tcal) wall temperatures histories in the upper, middle and bottom parts of the FA 

model, and also selection of time interval, corresponding Dtexp, and selection of time moment tlcal, 

corresponding t0exp for KS-lTest 35-1 are shown in Fig. B- 4. There is slow increase of mixture 

level in core channel and decrease of rod simulators temperature TW(tcal) in covered bottom part of 

the FA model at the level equal 0.562 m (see curves TW (teal) for heat structures 0071001 

0071005 in Fig. B-4). This calculation value for mixture level is nearly equal initial value of real 

mixture level 0.57 m in the test. 

Real mixture level is that level in the core channel, at which sharp increase of void fraction (see Fig. 

B-5) and local dry out of rod simulators, sharp decrease of heat transfer coefficient Hwl (tcal) and of 

specific heat flux qwl (teal) from outer surfaces of rods to coolant (see Figures B-6 and B-7, 

accordingly), local increase of temperatures TW (tcal) of rod simulators above saturation 

temperature take place (see Fig. B-4). 

Calculated Vg (teal) vapor and VL (teal) liquid velocities histories in the upper, middle and bottom 

parts of FA channel are shown in Figures B-8, B-9, accordingly. During "quasi-steady regime" stable 

Vg (teal) vapor velocities at different elevations in the core channel increase along the uncovered 

part of FA and ones maximum value is equal f 0.22 m/s in the upper part of the FA (see Fig. B-8). 

Reinolds number Reg= Vg .Dh /vg is equal - 900-1100. 

During "quasi-steady regime" VL (teal) liquid velocities at different elevations in the FA channel 

increase along the height of FA uncovered middle part and decrease along the FA uncovered upper 

part. Maximum VL (teal) value equals - - 1.7 m/s in the upper and middle parts of the FA model. 

Therefor, maximum value of drift velocity for CCF in the FA channel is equal (0.22 m/s +1.7m/s) 

-1.92 m/s.

39
Behavior of calculated TW (tcal) wall temperature histories in the upper, middle and bottom parts of 

the FA model are presented in Fig. 4. There is TW (tcal) temperature increasing in the upper part of 

FA model with rate dTW/dt & 0.85 K/s, which is larger then measured one at the level of 2.48 m 

with rate dTW/dt = 0.14 K/s (see curve TW06-00 (texp) in Fig. A-7, B-15). 

Calculated Ti (tcal) insulator inside wall temperatures increase to 572 K at the moment tcal= 365 s 

with rate dTW/ dt =0.19 K/s in the upper part of the FA model (see Fig. B-10), which is smaller than 

ones for rod simulator due to relatively large heat capacity of are considered massive parts of the 

Core model. 

Behavior of RELAP5/MOD3.2-calculated Hwl (tcal) coefficient of heat transfer from outer surfaces 

of rod simulators to coolant in the upper part of FA model is nearly steady during time interval 

tcal=365 - 465 s with very slow decrease due to Pout (tcal) decrease (see Fig. B-6). Maximum Hwl 

(tcal) value equals • 80 W/m 2-K in the middle part of the FA model, when Hwl (tcal) is equal ; 50

60 W/m2 K in the upper part of the FA model. 

Unsteady behavior of Hw2 (tcal) coefficient of heat transfer from coolant to the insulator, Hw3 (tcal) 

coefficient of heat transfers from outer surface of steel shroud to coolant in annular channel and 

Hw4 (tcal) in the upper and middle parts of the Core model are shown in Figures B- 11, B-12 and B

13, accordingly. 

Comparisons of measured and calculated rod simulator temperatures are shown in Figures B- 14 - B

23. As seen in Fig. B-IS, in "quasi-steady regime" calculated TW (tcal) wall temperature is much 

higher (up to 130 K) than measured ones at the FA outlet. This is one of the main problems of the 

code for our case. The reason for these deviations between experiment and calculations are too low 

Hwlz 50-60 W/m2 K (tcal) coefficient of heat transfer from outer surfaces of rod simulators to 

coolant in the upper part of FA model calculated by the code for CCF conditions in FA channel. 

Therefor, the temperature increase rate dTW/dt in calculations is much more, than measured ones. In 

this case under prediction for interphase heat transfer may be other reason for these deviations 

between experiment and calculations, also. 

As seen in Figures B-20 and B-2 1, in "quasi-steady regime" calculated wall temperature TW (tcal) is 

much lower (100 K below) than measured ones in the middle part of FA model. This is one of the 

main problems of the code for base case calculations with maximum time step dt max=0.01 s. 

The reason for these deviations between experiment and calculations are too large Hwl t 80 W/m 2K 

(tcal) coefficient of heat transfer from outer surfaces of rod simulators to coolant in the middle part 

of FA model calculated by the code for CCF conditions in FA channel. Sensitivity studies are

40
needed to determine the main reasons for these deviations between test data and calculations. 

As seen in Fig. B-18, only for temperatures TW03-08 (texp) and TW04-09 (texp), which were 

realized at the elevation - 1.78 m, code gives a good agreement with data in the upper part of FA 

model. However, code does not give the same temperature increase rate dTW/dt, as measured ones. 

Comparisons of base case (time step dt max=0.01 s) calculated core axial temperature profiles in the 

heated bundle at the moment tcal= 365 s and experimental core axial distribution of rod simulator 

temperatures TWi-k at the moment tOexp-O s are shown in Fig. 5.1. As seen, there is a significant 

quantitative and qualitative difference of calculated and measured core axial temperature profiles in 

the heated FA model. RELAP5/MOD3.2 under predicts TW (tcal) temperatures in the middle part of 

FA model and over predicts ones at the FA outlet.

850-

Li 

CKS1 -35-1 RELAP5/IVOD,3.2

(2•D- dAX TIME STI P=C.0i cal F- i- rlAAY TIM• STF P=fl.9 ,-,i

* z / - FA INNER ROW RODS ex4 

OM - FA OUTER ROW RODS exb 

A ý=A 

700 V 

650-!

550 

500

0.0

__I F. • I I L I I ý I i I I I s I I I I I I I . .. . . . . . . . . . . . . . . .

0.5 i.0 2.0

LEVEL (m)

2.5

Fig. 5.1. Comparison of RELAP5/MOD3.2-calculated core axial inside wall temperatures profile in 

the bundle heated tube for time moment tcal= 365 s, corresponding tOexp for KS-1 Test, and 

experimental core axial distribution of temperatures of rod simulators TWi-k of the FA Model for 

time moment tOexp.

41

7
Conclusions 

* Base case method of code simulation experimental conditions for the KS-1 Test 35-1 provides 

adequacy of the code simulation of initial and boundary conditions only for hydrodynamics, realized 

in the experiment. 

9 RELAP5/MOD3.2 gives a satisfactory agreement of calculation results and Test 35-1 data for 

overall picture of the two-phase flow behavior in KS-lVVER Loop model and heat transfer in 

partially uncovered Core model during reflux condenser mode with some exceptions. 

* Behavior of calculated Hwl (tcal) coefficient of heat transfer from outer surfaces of rod simulators 

to coolant in the upper part of FA model is nearly steady during considered time interval. Maximum 

Hwl (tcal) value equals 80 W/m 2XK in the middle part of the FA model, when Hwl (tcal) is equal 

50-60 W/m2 .K in the upper part of the FA model. 

* Behavior of calculated Hw2 (tcal) coefficient of heat transfer from coolant to the insulator, Hw3 

(tcal) coefficient of heat transfers from outer surface of steel shroud to coolant in annular channel 

and Hw4 (tcal) is unsteady in the upper and middle parts of the Core model. 

* In considered "quasi steady regime" calculated TW (tcal) wall temperature is much higher (up to 

130 K) than measured ones at the FA outlet. This is one of the main problems of the code for base 

case calculations. The reason for these deviations between experiment and calculations is too low 

Hwl (tcal) = 50-60 W/m2

EK (tcal) coefficient of heat transfer from outer surfaces of rod simulators 

to coolant in the upper part of FA model calculated for CCF conditions. Therefor, the temperature 

increase rate dTW/dt in calculations is much more, than measured ones. In this case under prediction 

for interphase heat transfer may be the other reason for these deviations between experiment and 

calculations. 

* In considered "quasi steady regime" calculated wall temperature TW (tcal) is much lower (100 K 

below) than measured ones in the middle part of FA model. This is the next one of the main 

problems of the code base case calculations. The reason for these deviations between experiment 

and calculation is too large Hwl (tcal) z 80 W/m2 .K coefficient of heat transfer from outer surfaces 

of rod simulators to coolant in the middle part of FA model calculated by the code for CCF 

conditions in FA channel. 

9 Only for temperatures TW03-08 (texp) and TW04-09 (texp), which were realized at the elevation 

-1.78 m, code gives a good agreement with data in the upper part of FA model. However, code does 

not give the same temperature increase rate dTW / dt, as measured ones.

42
* There is a significant quantitative and qualitative difference of calculated and measured core axial 

temperature profiles in the heated FA model. RELAP5/1M4OD3.2 under predicts TW (tcal) 

temperatures in the middle part of FA model and over predicts ones at the FA outlet. 

* Sensitivity studies are needed to determine the main reasons for these deviations between test data 

and calculations. 

5.3. Sensitivity Studies, including input deck modifications 

This assessment work has shown, that the frozen version of the RELAP5/MOD3.2 and base case 

method of code simulation experimental conditions for KS-I Test 35-1 provides adequate simulation 

of initial and boundary conditions only for hydrodynamics, realized in the test under reflux 

condenser mode. 

There is a significant quantitative and qualitative difference of calculated and measured core axial 

temperature profiles in the heated FA model at the initial moment t0exp. The code under predicts 

TW (tcal) temperatures in the middle part of FA model near mixture level and over predicts ones at 

the FA outlet. This is one of the main problems of the code base case calculations with maximum 

time step dt max=0.0 Is. 

The reasons for these deviations between experiment and calculations may be over estimation for 

Hwl coefficient of heat transfer from rod simulators to coolant in the middle part of FA and its 

under estimation in the upper part of FA model under CCF conditions. Sensitivity studies are needed 

to determine the main reasons for these deviations between test data and calculations. 

The main goal of Sensitivity studies is an attempt to reduce large differences between 

RELAP5/MOD3.2 predictions and measurements for core axial temperature profiles in the heated 

FA model at the initial moment tOexp in considered "quasi-steady regime" during the test 

simulation. 

For comparison the effect of maximum time step dt max = 0.2 s on calculated TW (tcal) wall 

temperatures histories in the upper, middle and bottom parts of the heated bundle is shown in Fig. 5. 

2. The effect of dt max = 0.01 s on calculated TW (tcal) is shown in Fig. B-4. 

Selection of time interval, corresponding texp= 0 - 100 s, and selection of time moment tIcal, 

corresponding t0exp, are shown too in Fig. 5.2 and Fig. B-4, accordingly. The effect of maximum 

time step dt max = 0.2 s on the calculated axial temperature profiles in the heated bundle at the 

moment tcal= 365 s is shown in Fig. 5.1. One can see, in the case with maximum time step dt max = 

0.2 s calculated axial temperature profiles in the heated bundle in the middle part of FA nearly

43
coincides with measured one, and in the upper FA part this profile dose not coincide with measured 

one. In the FA upper part both calculations give the same results, when the code over estimates rod 

simulator temperatures significantly (up to 130 K). Thus, using time step 0.2 s results in 

improvement code simulation axial temperature profiles in the heated bundle only for middle part of 

FA model. 

To simulate real axial temperature profile in the heated bundle at the moment tical =365 s, 

RESTART input deck of KS-1 Test 35-1 was used with setting up an experimental profile for FA 

model heat structures. Axial temperature profile was measured at the moment t0exp= 0 s in the rod 

simulators, located in the inner row in the bundle. In these rods the highest temperatures were 

obtained during the test. In restart calculation maximum time step was used equal dt max=0.01 s. 

The effect of RESTART calculation, with maximum time step dt max = 0.01 s being used up to the 

RESTART point in previous simulation, on calculated TW (tcal) wall temperatures histories in the 

upper, middle and bottom parts of the heated bundle is shown in Fig. C- 1. 

The effect of RESTART calculation, with maximum time step dt max = 0.2 s being used up to the 

RESTART point in previous simulation, on calculated TW (tcal) wall temperatures histories in the 

upper, middle and bottom parts of the heated bundle is shown in Fig. C-2. 

Comparison of behavior measured and calculated rod simulator temperatures with RESTART 

calculation, with maximum time step dt max = 0.01 s in previous simulation, are shown in Figures 

C-3 + C-12 in Appendix C. 

Analysis of code results shows, that implementation experimental temperature profile in restart input 

deck allow to reduce large differences between code predictions and measurements for core axial 

temperature profiles in the heated FA model at the initial moment t0exp and then in considered 

"quasi-steady regime" during the test simulation. However, because of restart calculated Hwl (tcal) 

coefficient of heat transfer in the upper part of FA model practically does not increase on 

comparison previous simulation results, rod temperatures stay increase with high rate. As 

consequence, a significant quantitative and qualitative difference of calculated and measured core 

axial temperature profiles in the heated FA model was achieved again with in the test time interval 

Dtexp. 

This fact shows that initial temperature conditions weakly influence on code simulation of heat 

transfer and interphase heat exchange in partially uncovered core under CCF conditions.

44
2cc 2cc5 

0 20C C0~ '0 50C 

_:c "S)

I tox excc - 2c 

KS -35-- I RELAe/xcD3.2 

-- • ( -- 071001 '[ 

- A %'X -.-0 200071003 0 I 0 S-07oo0,4

•751:t • -- 0071005 - --- 007t006 - ,->O--e< 007<007

"5 650

-r 0Cexc 

_C 200 300 ýOO T-i e (s'

I I 

. . .co D

Fig. 5.2. The effect of maximum user-specified time step on the calculated inside wall temperatures 

histories in the upper, middle and bottom parts of the bundle heated tube (tcal=0-600 s), and also 

selection of time interval, corresponding Dtexp, and selection of time moment tlcal, corresponding 

tOexp for KS-1 Test. dtmaxO0.2 s.

45

I
5.4. RUN STATISTIC 

The input model for RELAP5/MOD3.2 calculation for KS-35-1 test encompassed: 

198 - Volumes, 198 - Junction, 217 - Heat Structures, 982 - Mesh Points. 

During the transient calculation the following resources were used: 

Computer time CPU time = 7674.62 sec, Number of time steps DT = 60000, 

Number of volumes C - 198. 

Resulting in the following grind time (code efficiency factor): 

CPU •i 10_ 

Grind Time = CPU--101 - 0.0646 C.DT 

The computer used was IBM PC AT with processor INTEL Pentium-166. Operation system 

Windows 95 was used. The CPU time of KS-3 5-1 test can be seen in Figure. In figure the time step 

chosen by the code and the Courrant time step are shown.

8-KS -3S-1 R LAS/MV03.2 

6000 

E 4 0 . .... . ,_ _ 

4000 

0 " 200 3 0 0 6C 0 

Fig. 5.3. The required CPU time in the base case calculation.

1.6 $ -- 3 5 --i 

000C -- ur n -re scz

-2

C,, *V'/AfVV

c 5CC 62c0i 7 

2C '-C > 0 60C 0

Fig. 5.4. Time step size of base case calculation.

46

7

RE: 2
6. SUMMARY OF CONCLUSIONS

In this work some deficiencies of RELAP5/MOD3.2 in analysis of KS-1 Test 35-1 could be 

identified, and the following conclusions can be drawn: 

* Base case method of code simulation experimental conditions provides adequacy of the code 

simulation of initial and boundary conditions only for hydrodynamics, realized in the Test 35-1. 

* RELAP5/MOD3.2 gives a satisfactory agreement of calculation results and test data for overall 

picture of the two-phase flow behavior in KS-lVVER Loop model and heat transfer in partially 

uncovered Core model during reflux condenser mode with some exceptions. 

9 There is a significant quantitative and qualitative difference of calculated and measured core axial 

temperature profiles in the heated FA model. RELAP5/MOD3.2 under predicts TW (tcal) 

temperatures in the middle part of FA model and over predicts ones at the FA outlet. 

* Behavior of calculated Hwl (tcal) coefficient of heat transfer from outer surfaces of rod 

simulators to coolant in the upper part of FA model is nearly steady during considered time interval. 

Maximum Hwl (tcal) value equals ; 80 W/m 2

.K in the middle part of the FA model, when Hwl 

(tcal) is equal z 50-60 W/m2.K in the upper part of the FA model. 

a In considered "quasi steady regime" calculated TW (tcal) wall temperature is much higher (up to 

130 K) than measured ones at the FA outlet. This is one of the main problems of the code base case 

calculations. The reason for these deviations between experiment and calculations is too low Hwl 

(tcal) ; 50-60 W/m2.K (tcal) coefficient of heat transfer from outer surfaces of rod simulators to 

coolant in the upper part of FA model calculated for CCF conditions. Therefor, calculated 

temperature increase rate dTW/dt is much more, than measured ones. In this case under prediction 

for interphase heat transfer may be the other reason for these deviations between experiment and 

calculations. 

e In considered "quasi steady regime" calculated wall temperature TW (tcal) is much lower (100 K 

below) than measured ones in the middle part of FA model. This is the next one of the main 

problems of the code calculations. The reason for these deviations between experiment and 

calculation is too large Hwl (tcal) 80 W/m2.K coefficient of heat transfer in the middle part of FA 

model calculated for CCF conditions. 

e Sensitivity studies shows, that implementation experimental temperature profile in restart input 

deck allow to reduce large differences between code predictions and measurements for core axial 

temperature profiles in the heated FA model at the initial moment tOexp and then during the test

47
simulation. However, because of restart calculated Hwl (tcal) coefficient of heat transfer in the 

upper part of FA model practically does not increase on comparison previous simulation results, rod 

temperatures stay increase with high rate. As consequence, a significant quantitative and qualitative 

difference of calculated and measured core axial temperature profiles in the heated FA model was 

achieved again with in the test time interval. 

* Sensitivity studies show, initial temperature conditions in FA model weakly influence on code 

simulation of heat transfer and interphase heat exchange in partly uncovered core under CCF 

conditions. 

REFERENCES 

1. V.G.Sorokin, A.V.Volosnikova, S.A.Vyatkin. Types of steels and alloys. M. Mashinostroenie, 

1989 (In Russian). 

2. Electrotechnical hand book. M.-L., GEl, 1962 (In Russian). 

3. L.L. Kobzar, V.A.Vinogradov, A.Y. Balykin. Investigation of temperature regimes for partly 

uncovered core at the KS test facility. RRC KI Report N32/1-1386-91, 1991, 117 p. 

4. RELAP5/MOD3 Code Manual Volume 4: Models and Correlations. INEL-95/O 174, NUREG/CR

5535. 1995. 

5 RELAP5/MOD3 Code Manual Volume 2: User's Guide and Input Requirements INEL-95/0174, 

NUREG/CR-5535. 1995.

48
APPENDIX-A

ORIGINAL DATA PLOTS FROM KS-1 TEST 35-1

A-1
Original Data Plots from KS-lTest 35-1

K3b -

D 2 -2 

Fig. A-1. FA model heat release power history W(t) (texp=O-100 s).

KS -3

60

:,- LC

0 

] r

- /c -~X3 " S,

Fig. A-2. Measured Pout(t) Core model outlet pressure history (texp=O-100 s). 

A-2

,ý- 2 - .-

all
Original Data Plots from KS-iTest 35-1

750 

C

E 

55C

]

1 

22 £2 00 C

320 40 6 0 89! C 

iexlie cmre 

Fig. A-3. Measured TFin(t) Core model inlet coolant temperature history (texp=O- 100 s).

850

KS' 3 

I p 

~1 dP

-650 

E

550

450

2x t0

Fig. A-4. Measured TFfa(t) FA model outlet and TFup(t) UP model inlet coolant 

temperatures histories (texp=O-100 s).

A-3

]3
Original Data Plots from KS-lTest 35-1 

KS- -55-I

8 003

S 60030 

a c a

S. . . . .

20C3C

,9 23' 0 " ,ex-, Cýre (s)

Fig. A-5. Measured DL13-12(t) UP model, DL2-4(t) 

pressure histories (texp=0-100 s).

and DL4-14(t) DC model differential

KS -55-i

4 0.

1© 

-cD

"200 -,', r' 

c D-9-8- Z (• D- 7-6 

D, 5 S.-

2" 60 lex/ ,,:,

8

Fig. A-6. Measured DP4-3(t), DP5-4(t), DP6-5(t), DP7-6(t), DP8-7(t), DP9-8(t) and DP1 1

10(t) Core model differential pressure histories (texp=0-100 s). 

A-4

/24
Original Data Plots from KS-1Test 35-1

KS2 -2 

1

E -8 _

0

• - -• - 6 -00 

20 4 

te .. e 6c 8C

XD/ U

Fig. A-7. Measured TW06-00(t), TW12-00(t), TW16-00(t) and TWl8-00(t) heated tube 

inside wall temperatures histories at the top of the FA model (texp=O-100 s).

75C

650

550

&Gee- -7 

A-A- - 7\- - C

23

2 

3 

C) 

(0S *• X N

Fig. A-8. Measured TW03-02(t), TW04-03(t) and TW13-03(t) heated tube inside wall 

temperatures histories in the upper part of the FA model (texp=O-100 s).

A-5

, cc

450 'cc 8

r -
Original Data Plots from KS-lTest 35-1

A A A A 

V V V V 

Z2--

2

C7- - - t T`- _7ý- 'ý 7 - 0 

q - T'/'_ Z--0L 

TV, 0 . ,6 

2C 43 60 a C, 

3- s

Fig. A-9. Measured TW07-04(t), TW14-04(t), TW04-06(t) and TW13-06(t) heated tube 

inside wall temperatures histories in the upper part of the FA model (texp=O-100 s).

750 oDC 

750C

2 7• :4 - 7 

7',03-38 

TW-13 - 09

4C K 8 iexs i,•c ,\s

Fig. A-10. Measured TW14-07(t), TW03-08(t), TW04-09 (t) and TW13-09(t) heated tube 

inside wall temperatures histories in the upper part of the FA model (texp=O-100 s).

A-6

-8 6so, 

E U

550

L50

nD,

7 5 ý D
Original Data Plots from KS-lTest 35-1

750-

D 

0 

C) 

E 

U

- -~ TW-07- C 

4 -- TW- 0- 1 

C 2 4-C 60 880 

týexs -me \-e l

Fig. A- 11. Measured TW14-10(t), TW07-10(t) and TW03-1 1(t) heated tube inside wall 

temperatures histories in the middle part of the FA model (texp=O-100 s).

KSI 3-5 850 

-9-

-. TW-04 7•-£-•-3d Vl'!-C2-

20 7.-9-" 

2'0 4C 

,ex- :Sff

Fig. A-12. Measured TW04-12(t),TW02-13(t) and TW19-15(t) heated tube inside wall 

temperatures histories in the middle part of the FA model (texp=O-100 s). 

A-7

0

4-51
Original Data Plots from KS-lTest 35-1

85C

F 

0- -

C) 

650E

A-A-A-A-s - 6

40 60 4 XC 6ec1

Fig. A-13. Measured TW09-16(t), TW02-16(t) and TW17-16(t) heated tube 

temperatures histories in the middle part of the FA model (texp=O-100 s).

K S1 -3~

750 -li 

----. • "• o1

*'7-1 

23 i 

Lex- -L.',e s;

Fig. A-14. Measured TW19-18(t), TW09-19(t) and TWl7-19(t) heated tube inside wall 

temperatures histories in the bottom part of the FA model (texp=O-100 s).

A-8

-Cý

inside wall

D 

-• s5
Original Data Plots from KS-1Test 35-1 

<S/ -35- -

7C0

0

c650

-, o- Ae - - T -i 9 - 21 TV,/ --02 -22 

-ea-iTW1- - 7-22 

C, 20 43 s0 ac '0 

texs -,me Sz s

Fig. A-15. Measured TW19-21(t), TW02-22(t) ,TW17-22(t) and TW19-24(t) heated tube 

inside wall temperatures histories in the bottom part of the FA model (texp=O-1 00 s). 

A-9

450 J•
APPENDIX- B 

BASE CASE RESULTS

B-1
KSI -35- A /v 2

2,CD 

2C.-

- cc, 

-exp 

d2 

t .0exDý -,`-0C 

0 c 2--c 5 C - 5CC 6-C 70 

7i- ýsi

Fig. B-1. RELAP5/MOD3.2-calculated Pout(t)cal pressure at Core model outlet 

(tcal=0-600 s). 

KS -:55 6C 

, i:

I0 -

5 -

7 

020 40 S0 so '0O(

Fig. B-2. Comparison of measured Pout(t)exp and RELAP5/MOD3.2-calculated 

Pout(t)cal pressure at Core model outlet (texp=0-100 s).

E

K<S' -35--1 850

= • -- 00' 66CCOO 

75C 

650C 

558 

C 20 C-0 6C 8D 1GO 

texp ; C s

Fig. B-3. Comparison of measured and RELAP5/MOD3.2-calculated TFin(t) 

coolant temperature at Core model inlet (texp=O- 100 s).

B-2

U.0

- 2C
75(

450

- -cc 2cc[ 

"i Oexp: • :Sexs 

10c 200 3 '00 503 -i•e (S) 60 7C

85O KS' -z

C0 SC 4C T-ce 's

R .A-5/MC DV-.2

850

7 50 , :o 1 1• 007 007 •,007 005 

S• -,007 006 

650 

0550 .00. ... 0,0. 0 00 20'- ,BOOC 400 Soo 600 7,' 

-i-e 's'

Fig. B-4. RELAP5/MOD3.2-calculated TW(t) heated tube inside wall 

temperatures histories in the upper, middle and bottom parts of the FA model 

(tcal=0-600 s). 

B-3
- ^ - 0703 

a > O ~ O . - 0 2 3 0 6 ,, 

-- [, , J • " ,• 

,0.4 

! 

0.2 

IO: e xpý -ýel 0.! CO 2C0 3110 400 5,00 6010 72C 

Fig. B-5. RELAP5/MOD3.2-calculated void fractions histories in the bottom part 

of FA channel (tcal=O- 600 s).

B-4

U.•
6C ATh/VC.2

120 -1- 1 n 7l ')15 

4ý 007 0' 7 

00710!9C 

20• 

40 

7~-

G0 20

C cc, t2cc! 

tCexo: tlexn 

' 300 400 530 S00 7C0

RELAP .V%/O D

j 

-'i e E: 0 0 7 1 0 0 8 

2- 2071CQ "20 , ' C71 071 C'- 0 

C0071C,11 

C-• 071 C-.2 

-eeee<- CC71o0 

80:- 4

KS 5 1 RELAP5/MO03.2 

: S~ 0.07 0C2 

007> 0C0C7 

007, 004 007 i O05 ,,i- ,0 0-- 7100C6 ] 

> • -- i 0071 CC7

I 

. .. . . . ..... .... . 

200 300 400 Soo 6C T:-e (s)

Fig. B-6. Behavior of RELAP5/MOD3.2-calculated Hwl(t) coefficient of heat 

transfer from outer surfaces of rod simulators to coolant in the upper, middle and 

bottom parts of FA model (tcal=0-600 s). 

B-5

23 CO 

"5 C000

ýCo 

0 6

CO 700A

L4 y. 

E

i
RELAP2/ ODS.2

-e :s

8000

70 0

:6000

E 

500C 

4300

3000 

2000 

1000

1 C 

300 

20 000 30000 

E 

v200CO

2 1

-: e (s 60C . 73C

Fig. B-7. Behavior of RELAP5/MOD3.2-calculated qwl(t) specific heat flux from 

outer surfaces of the rod simulators to coolant in the upper, middle and bottom 

parts of FA model (tcal=0-600 s).

B-6

I i

2 1 Oc 2
-. 0

1oo-e (S)

Fig. B-8. RELAP5/MOD3.2-calculated Vg(t) junction vapor velocities histories in 

the upper, middle and bottom parts of FA channel (tcal=0-600 s). 

B-7

6•

KS'. -35-1 LAP5/V©D>2 

'C IC 6 007 ý0 116 7

-- . , i C07' 01!9 C07 020 

0 1C0 200 300 LC . 6 0C C 

71ýe (s, 

KSI -:55-' - E A-5/ CD32 

- C0710~8 

CO-7.OO 0093 

C07 i2cC 0c 

- - 20 0 

"D'DS1 -071 -4A5v.C. 

fi t~~~Oexpz ] iex 

0 01 260 306 4-CO 500 600 700 

Ti-e (s) 

KS 1--35-1- RELAP5/MO,-3.2 

: - 0 071008 

007 003 

c0071004 

00 1 00 

6/ iýl0 " 

]• !cc t2ccý 

0 i 00 200 30 4'C 500o 600 700

*.O

S

-C.0 

-0.5

(S
RE._A Z VCD3.2

' c5

KS' -05- 1

0 2OC 30 -CCO C 60 C' 7

RELAP5i /VD. 2

1cc t2cc: 

Cc:Oxc' . tlexc 

C 20 00 4 0C 7-T~ (S,SCO 7CC

Fig. B-9. RELAP5/MOD3.2-calculated VL(t) junction liquid velocities histories in 

the upper, middle and bottom parts of FA channel (tcal=0-600 s). 

B-8

-C.

2. -

-C.5 

S

2. 

-23

Si

I

1 .

RE'-AP5iVCDZ.2
KS1 -35- " RELAP /V,0 D3.2 

750 S•-- 0072016 

00720 7 

.;- q C720 - 9 S• - 007202C 

650 

S0exo <C1exo 

450 

0 C0 20C 300 400 50c 600 7CC 

850 KS KS 1 --- - R 835- A=55/\ CD 0 .2 

75O 

-- EE • - 00372008 

753 -- Q 072009 -!00720-C 00:O72011 

0720 S• 00720'3ý St 00 -- 0-07 20 4. 

650 i 

I ccl t2,ccý 

45 1 0e x tl , .XD 

c o 200 3C0 ýzcc 500 600 700 

T!-e (s) 

85-KS.' -35-- 1. R-LA-S/MCC3.2 

G(99C -- 0072C0C!

0072C05: 72004. S00O 

S-C0C720067 q_.,>4•<>• - C072007 

650 

550 _I .. , .

450

cc St' 

100 2C0 300 40C 

Time s,

:2L 

. 2 r . .

500 S00 7C:

Fig. B-10. RELAP5/MOD3.2-calculated Ti(t) insulator inside wall temperatures 

histories in the upper, middle and bottom parts of the FA model (tcal=0-600 s). 

B-9

I 

I 

I
RET-A=5,/h-V .2

300 

E20

:2co 

Stexp 

0 10C 20C 330 4 00 50C 660 70

zREA?/VOD3.2

20 

q1

c 20c

0072008 C07200-9 

00720 1 

00720'1 

0,720'3

:'ccl t2<cc 

t0exo. exc 

33 40C 58C C Ti-e (s' 632 72

Ks'SS,

D*An*- "''c

SOOC 

6 00C 

2COC

7-e Is)

Fig. B-11. Behavior of RELAP5/MOD3.2-calculated Hw2(t) coefficient of heat 

transfer from coolant to the insulator in the upper, middle and bottom parts of FA 

model (tcal=0-600 s). 

B-10

- • C 072Q015 ~- I - •-0072C016 -•-- C720- 17 

0072 C 1 8 S: 00720-19

KSI 

-3.5- 

"

KS1--35--'

I

-'•-e Is,
-KS-35 - R A 5/V 3 2

3 

2.

2 * c0C :2scc 

S IC 2SO JCO"C 530 

T-*-ce ( s cc 7-C 

R LAý5 / VS.

50

-4 

2

20

HIt c i i2cc[ 

:Oeez 

C CO 200 360 400 -c0 6 

Tme 's)

:C

Fig. B-12. Behavior of RELAP5/MOD3.2-calculated Hw3(t) coefficient of heat 

transfer from outer surface of steel shroud to coolant on the height of Core model 

annular gap (tcal=0-600 s). 

B-11

<S -35-

O

so-0, 35
14 

E 

6~30 

r),C

2cc t24cc: 

7ýe (Sx,

cc KS -35-1

600 7ý 

RELAP /VOD3.2

,Oexp - exp

14 

C)

20C 300 c 5c 600 7C 

-me s) 

160KS--5-- RELAP5/VOD,ý.2 

180 2 EEEEE-0o52o0C 1 2 0 Rd • -- 0 0 2 2 

00520C4 

00520C5 S 00520C6 

'->0'G- 00520C7 

80(

0. 0- O0 200 300 400 500 6C3 70, 

I Is,se 

Fig. B- 13. Behavior of RELAP5/MOD3.2-calculated Hw4(t) coefficient of heat 

transfer from coolant to inner surface of pressure vessel on the height of Core 

model annular gap (tcal=0-600 s). 

B- 12
650

EEH__• 7 0-09020,0020

KS -55-,

4:2 / u

6CS 4

0 

:500

0 20 Zcso 80 oc 

-exp - •' (sý 

Fig. B-14. Comparison of measured and RELAP5/MOD3.2-calculated TFfa(t) FA 

model outlet and TFup(t) UP model inlet coolant temperatures histories (texp=0

100 s).

850

75C

KS'-35-' 

-f

0 

- rN r-> CN C> 

I

5_ 

a 

:55

A 

4 • TW-06-00 

STW - -12-CC 

• TA-816-00 TWI - 1 8 - 00 

--. 0071020 

3 20 -60 (S) 80 

texo tine (s)

Fig. B-15. Comparison of measured TW06-00(t), TW12-00(t), TW16-00(t), 

TW 18-00(t) and RELAP5/MOD3.2-calculated heated tube inside wall 

temperatures histories at the top of FA model (texp=0-100 s). 

B-13
85C

7 5 ,

550 

"c5

T VW-3- 2 3 Oz--3 

O 2 400719 

2 3 4 8 00 a ,

:exp ,- R

Fig. B-16. Comparison of measured TW03-02(t), TW04-03(t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

upper part of FA model (texp=O-100 s).

KS' -35-1 

I

750- "__ __" 

850 

©1 

550

- :7W-Z-n6

0 2 C O <- 6 0 C0" 

ex. :me s 

Fig. B-17. Comparison of measured TW07-04(t), TW04-06(t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

upper part of FA model (texp=O-100 s). 

B-14

)0

39 30- T - 7 

•~-7 00737
KS, -Z-7

850

7K -7 I..=- - -

C

20

L~X i- e

Fig. B-18. Comparison of measured TW03-08(t), TW04-09 (t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

upper part of FA model (texp=O-100 s).

KS' -35-

850

750

550

i1

7 Tv'i- i z- 0 

- TW-07- 10 

45V/ - 007 - 1 

45exo 0 720 C 

2CLC 00 

/ \ R " /

!00,

Fig. B- 19. Comparison of measured TW 14-1O(t), TW07-1O(t), TW03-11 (t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

middle part of FA model (texp-0-100 s).

B-15

2- "V,' 7 3 58
K!

750,

52

bU' 

a.-

G•e9D - 80"1 c 1 7

I

22 L'O -2 80 '182 

e x -e RSl 

Fig. B-20. Comparison of measured TW04-12(t),TW02-13(t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

middle part of FA model (texp=O-100 s). 

850

2' 

a A A A

C 

a 

C

3- - TV--0 9 -- 6 

-T,- 7- 

,, 7009

0 £

Fig. B-21. Comparison of measured TW09-16(t), TW02-16(t), TW17-16(t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

middle part of FA model (texp=O-100 s). 

B-16

/Zý -:7Ty- 02-' ' <>0-099O - o07"o•l
KS --Z--

850

- --c --

E~ _______ 

C)

T C 90-7 "9

20

SC07!S, CC

4 t I 6 

ýe t- e (s)

Fig. B-22. Comparison of measured TW19-18(t), TW09-19(t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

bottom part of FA model (texp=O-100 s). 

-35-1 

850

2 - TV'V- 9-24 A 1ý - 22,,E-02_22!, TV/,- 9 - 2 

, C 0 OC- 00 100 4 O - 071005 - I ý7106 7! 

75O 

550 , 

Zf 2CK 

45C ) 

O 2C 40 6-1 SO 

exp os) -me 

Fig. B-23. Comparison of measured TW19-21 (t), TW02-22(t), TW 19-24(t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the 

bottom part of FA model (texp=O-100 s). 

B-17

-5C
APPENDIX- C

SENSITIVITY STUDIES

C-1
- •-,C0710C1,6 -C- 071 c1 7 0371C 8 

i iCOT7C2C

75C

655

,,cc -z2ccl 

t!CeX; '2CeXI

c CO 200 00 430 5cC 600 7C 

KSi -35- RE -A-5/ VC3.2 

- • -- C0710Th2 , ]

C07100J03 

0071004 

C071006 

071 007

650

50

]tcex;ý 

0 2:0 30063 

Tie (s) 600 70ý

Fig. C-1. RELAP5/MOD3.2-calculated TW(t) heated tube inside wall temperatures 

histories in the upper, middle and bottom parts of the FA model (tcal=0-600 s). Maximum 

time step =0.01 s. Restart time t=365 s. 

C-2
e :2ccJ 

20 303 C -0Cc 80 7;-e •s,

65(

300 Trme (s,

KS' -- 35-- 1 

7~ 

650 

7 

750 q C--0©7 -. 00 

q z•-0071 CC3 

• •--007',005 

S" S><) ->G>< } 00- 3 07 0 7

2cc 

tcexc-ý-x 

2X 3C 300 " C 5 6CC 7 CTI c Is)

Fig. C-2. RELAP5/MOD3.2-calculated TW(t) heated tube inside wall temperatures 

histories in the upper, middle and bottom parts of the FA model (tcal=0-600 s). Maximum 

time step =0.2 s. Restart time t=365 s. 

C-3

73CO

RE-A -S/M3 C.2

450
rSz-5 1 6Cexc 

£•,-- -$ C -i 

I

cr

2 -

7

/• 0

Lex: r-I~

Fig. C-3. Comparison of measured Pout(t)exp and RELAP5/MOD3.2-calculated Pout(t)cal 

pressure at Core model outlet (texpO--100 s).

CC 

'-§7 ___

5,

2- T 120 - 3 

2 C a 

-ex--, -:'71e

Fig. C-4. Comparison of measured TW06-00(t), TW 12-00(t), TW 16-00(t), TW 18-00(t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories at the top of 

FA model (texp=O- 100 s). 

C-4

0 

a

'd
KS1- 51

850

7-50.

-

]t K/ -~K :T'iv' 05 - • - TY,,- -3 S@ 0- 0- 0710'9 ,--d E - 0 7181 

0 6 

tex: tm , s

Fig. C-5. Comparison of measured TW03-02(t), TW04-03(t) and RELAP5/MOD3.2

calculated heated tube inside wall temperatures histories in the upper part of FA model 

(texp=0- 100 s) 

KS1 -35-i 

850 

750

LL'->

ID 

-7ý 650

/ __ - !T 3Z - 06 0@ {- i007!01 6

2

T%-/07 -0'4 

007',• 0' 7

:exp t:me

Fig. C-6. Comparison of measured TW07-04(t), TW04-06(t) and RELAP5/MOD3.2

calculated heated tube inside wall temperatures histories in the upper part of FA model 

(texp=0-100 s)

C-5

I
85

- C 

-

i88~.-5' 

20 4 6 0 8 3

Fig. C-7. Comparison of measured TW03-08(t), TW04-09(t) and RELAP5/MOD3.2

calculated heated tube inside wall temperatures histories in the upper part of FA model 

(texp=O-100 s) 

S 

850 

t:

C_.

E 

C.

2ni 

f TI 0 V" 7 10' 

.2 0 

-exD -:_e

Fig. C-8. Comparison of measured TW14-10(t), TW07-10(t), TW03-11(t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the middle 

part of FA model (texp=O- 100 s) 

C-6

/DU

hff
KS -35-.

850 

650 , CA IN

TV,/- 02 - 1 

OC710-

2

G C -T,-0 z- 2 -00C 2

0c es text :-me(s

Fig. C-9. Comparison of measured TW04-12(t), TW02-13(t) and RELAP5/MOD3.2

calculated heated tube inside wall temperatures histories in the middle part of FA model 

(texp=0- 100 s) 

Ks" -35-, 

850

0 

C)

:5, S

7 21 45' ~ K 2

TW-09- 6 

0,07 009 

z-O 

tex3 tie

Fig. C-10. Comparison of measured TW09-16(t), TW02-16(t), TW17-16(t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the middle 

part of FA model (texp=O- 100 s)

C-7

60 80

t

Z-5 ,

o
KS': - 3.5- 1

850

2 

2 

'.- 

0''-

- a 

2 60 81 

SexD t /ý7 (sy

Fig. C-11. Comparison of measured TW19-18(t), TW09-19(t) and RELAP5/MOD3.2

calculated heated tube inside wall temperatures histories in the bottom part of FA model 

(texp=O- 100 s)

- , TV",.'-9-2L- - -/-02 22G999 ,'-19-2 1 - 00--71004 0 07 0COý - 0A7/'C6

~X 'Y .-

Fig. C-12. Comparison of measured TW19-21(t), TW02-22(t), TW19-24(t) and 

RELAP5/MOD3.2-calculated heated tube inside wall temperatures histories in the bottom 

part of FA model (texp=0- 100 s) 

C-8

0

0650 

0 \•,r
60 KSI 36- -- I R APz/VO0Z.

KS. -- 35-1 i RE-A-P5/VOD .2 

30 20,20tC 0 60 7 

0C71 008 - •i C71 CIC 

'007 10C1" 0C7 121 

00 C71012 

0 ccO 200 300 4 oO 560 00 70C 

coo - 5- •LA5 M ~ .

7 c 's 

- , , C• , . . 

0 0 2T m0 0s 5, ,C 0 7

Fig. C-13. Behavior of RELAP5/MOD3.2-calculated Hwl(t) coefficient of heat transfer 

from outer surfaces of rod simulators to coolant in the upper, middle and bottom parts of 

FA model (tcal=0-600 s),dtmax=0.01 s Restart t=365 s. 

C-9

2ý

iC0oo

?-:

.2,

KSI--35--I REL-AP5/VOD--.2

'2

I
<6 3 -A A -

-I 

1

t2cc 

-1 xc 

C . . . .

6C IKS'--35--11 160 _oS 1oo 

"20 -- 0071008 

0071014

RE AP5/V .D.2

]

texp,

ICC 200

-,2cC c0 

A-C -0C 600 7CC

2" KS" R E LA5 V ODD 3.2 

20000 -. 22 

)ccx( 007 004 

00070 

-C000 S- -71006 • -- : 007100C7 : 

i 2 c! r 

C -07 200-j>- 2O40 5C 600 700

Fig. C-14. Behavior of RELAP5/MOD3.2-calculated Hwl(t) coefficient of heat transfer 

from outer surfaces of rod simulators to coolant in the upper, middle and bottom parts of 

FA model (tcal-0-600 s) ),dtmax=0.2 s Restart t=365 s. 

C-10

007>01c 

0 07107 

C071016 

0071019 

-071020

120 ' ___

0 C 1ý00 20c

,t~excl 

300

E.

' I

KS' -35-

i 6C zý-- A'ýý/VCD-' 2

E

I 600
APPENDIX- D

BASE CASE INPUT DECK

D-1
Steady state base case input deck listing of KS-1 test 35-1 

=ksl 35 01 test 

*Input Deck for KS1 -VVER-1000 Tests 

*Assesment of RELAP5/MOD3.2 against KS1 test 35-01 

************

0000100 new stdy-st 

*0000101 inp-chk 

0000102 si si 

0000104 cmpress 

0000110 air

* Time Steps Control Cards 

*crdno time min__dt maxdt ssdtt minor major restart 

0000201 10. 1.0-6 0.005 15003 200 10000 10000 

0000202 1000. 1.0-6 0.100 15003 100 10000 10000 

HYDRODYNAMIC COMPONENTS 

* LOWER WATER COMMUNICATION LINE, components no v.l,sj2 

0010000 water pipe *component no v.1 

0010001 69 

0010101 3.32-3 22 * water pipe dh=0.065 m 

0010102 3.14-4 32 * water pipe dh=0.020 m 

0010103 3.32-3 69 * water pipe dh=0.065 m 

0010201 3.32-3 09 * water pipe dh=0.065 m 

0010202 1.13-4 10 * water pipe dh=0.065 m 

0010203 3.32-3 21 * water pipe dh=0.065 m 

0010204 3.14-4 31 * water pipe dh=0.020 m 

0010205 3.32-3 43 * water pipe dh=0.065 m 

0010206 1.13-4 44 * water pipe dh=0.065 m 

0010207 3.32-3 68 * water pipe dh=0.065 m 

0010301 0.425 4, 0.4 8, 0.355 18, 0.4 22, 

0010302 0.7 32 

0010303 0.4 35, 0.355 45, 0.355 65, 0.375 69 

0010601 -1.0 4, -90.0 8, 0.0 18, 90.0 22, 

0010602 -3.3 32 

0010603 -90.0 35, 0.0 45, 90.0 65, 1.0 69 

0010801 5.0-5 0.065 22 

0010802 5.0-5 0.020 32 

0010803 5.0-5 0.065 69 

0010901 0.0 0.0 3, 0.5 0.5 4, 0.0 0.0 7, 0.5 0.5 8 

0010902 0.0 0.0 17, 0.5 0.5 18, 0.0 0.0 21 

0010903 0.5 0.5 22, 0.0 0.0 31, 0.5 0.5 32, 0.0 0.0 35 

0010904 0.5 0.5 36, 0.0 0.0 45, 0.5 0.5 46, 0.0 0.0 65 

0010905 0.5 0.5 66, 0.0 0.0 68 

'crdno tlpvbfe 

0011001 0010000 69 

*crdno fvcahs 

0011101 001000 68 

*crdno 

*0011201 102 4.20+6 1.0 0.0 0.0 0.0 6 

*0011202 102 4.20+6 0.0 0.0 0.0 0.0 7 

0011203 103 4.20+6 516.0 0.0 0.0 0.0 69 

*0011204 102 4.20+6 0.0 0.0 0.0 0.0 51 

*0011205 102 4.20+6 1.0 0.0 0.0 0.0 69 

00113001 

0011301 0.0 0.0 0.0 68

0020000 sj2 sngljun *crdno from to area floss rloss fvcahs 

0020101 001010000 021020003 3.32-3 0.85 0.45 001100 

0020201 0 0.0 0.0 0.0

D-2

* LOWER PLENUM MODEL, components no v.21,sj22,v.23 

0210000 lowplenm annulus * component no v.21 

0210001 5 

0210101 0.044 1,0.0574 4, 0.02243 5 

0210301 0.09 1,0.08 2,0.05 5 

0210601 90.05 

0210801 5.0-5 0.14 1, 5.0-5 0.22 4, 5.0-6 0.102 5 

0210901 0.0 0.04 

*crdno tlpvbfe 

0211001 0010000 5 

*crdno fvcahs 

0211101 001000 4 

0211201 102 4.20+6 0.0 0.0 0.0 0.0 1 

0211202 102 4.20+6 0.0 0.0 0.0 0.0 2 

0211203 102 4.20+6 0.8 0.0 0.0 0.0 5 

02113001 

0211301 0.0 0.0 0.0 4 

0211401 0.140.0 1.0 1.0 1 

0211402 0.22 0.0 1.0 1.0 3 

0211403 0.102 0.0 1.0 1.0 4 

0220000 sj22 sngljun *crdno from to area floss rloss fvcahs 

0220101 021010002 023030001 2.14-3 0.0 0.0 101100 

0220110 0.013 0.0 1.0 1.0 

0220201 0 0.0 0.0 0.0 

0230000 Iowplenm pipe * component no v.23 

0230001 6 

0230102 0.00973 5, 3.09-3 6 

0230301 0.06 1, 0.09 2,0.08 3, 0.05 6 

0230601 90.0 6 

0230802 5.0-5 0.0429 5, 5.0-6 9.73-3 6 

0230901 0.0 0.0 5 

*crdno tlpvbfe 

0231001 0010100 6 *crdno fvcahs 

0231101 001000 5 

0231201 102 4.20+6 0.0 0.0 0.0 0.0 1 

0231202 102 4.20+6 0.0 0.0 0.0 0.0 4 

0231203 102 4.20+6 0.8 0.0 0.0 0.0 6 

02313001 

0231301 0.0 0.0 0.0 5 

*0231401 0.0429 0.0 1.0 1.0 2 

0231402 9.73-3 0.0 1.0 1.0 5 

*CORE MODEL, components no sj24,v.5,sj25,v.7,sj8 

0240000 sj24 sngljun *outside annulus inlet *crdno from to area floss rloss fvcahs 

0240101 021050002 005010001 0.0 0.5 0.5 001100 

0240201 0 0.0 0.0 0.0 

0050000 outside annulus *component no v.5 

0050001 20 

0050101 0.02243 20
0050301 0.125 20 

0050601 90. 20 

0050801 5.0-5 0.0255 20 

0050901 0.0 0.0 19 

*crdno tlpvbfe 

0051001 0010000 20 

*crdno fvcahs 

0051101 001000 19 

*0051201 103 4.20+6 489.0 0.0 0.0 0.0 2 

*0051201 102 4.20+6 1.0 0.0 0.0 0.0 1 

0051202 102 4.20+6 1.0 0.0 0.0 0.0 20 

0051300 1 

0051301 0.0 0.0 0.0 19

0250000 sj25 sngljun *core pipe inlet 

*crdno from to area floss rloss fvcahs 

0250101 023060002 007010001 0.0 0.15 0.15 001100 

0250201 0 0.0 0.0 0.0 

0070000 core pipe * component no v.7, bundle 

0070001 21 

0070101 1.8065-3 20 

0070102 3.09055-3 21 

0070301 0.125 20 

0070302 0.120 21 

0070601 90. 21 

0070801 1.0-5 9.75-3 20 

0070802 1.0-5 16.07-3 21 

0070901 0.0 0.0 1 

0070902 0.26 0.26 2 

0070903 0.0 0.0 3 

0070904 0.26 0.26 4 

0070905 0.0 0.0 5 

0070906 0.26 0.26 6 

0070907 0.0 0.0 7 

0070908 0.26 0.26 8 

0070909 0.0 0.0 9 

0070910 0.26 0.26 10 

0070911 0.0 0.0 11 

0070912 0.26 0.26 12 

0070913 0.0 0.0 13 

0070914 0.26 0.26 14 

0070915 0.0 0.0 15 

0070916 0.26 0.26 16 

0070917 0.0 0.0 17 

0070918 0.26 0.26 18 

0070919 0.0 0.0 19 

0070920 0.4 0.4 20 

*crdno tlpvbfe 

0071001 0010100 21 

*crdno fvcahs 

0071101 001000 20 

*0071201 102 4.20+6 0.0 0.0 0.0 0.0 1 

0071202 102 4.20+6 1.0 0.0 0.0 0.0 21 

0071300 1 

0071301 0.0 0.0 0.0 20 

0071401 9.75-3 0.0 1.000 1.00 20 

0080000 sj8 sngljun *core channal outlet 

*crdno from to area floss rloss fvcahs 

0080101 007210002 009020003 0.0 1.3 0.7 001100 

0080110 16.07-3 0.0 1.0 1.0

0080201 0 0.0 0.0 0.0

*UPPER PLENUM MODEL, components no v.9,sjlO,v.11 

0090000 outchanl annulus * component no v.9 

0090001 3 

0090101 81.0-3 1 

0090102 65.0-3 3 

0090301 0.1 1,0.05 2,0.1 3 

0090601 90.0 3 

0090801 5.0-5 0.0 3 

0090901 0.0 0.0 2 

*crdno tlpvbfe 

0091001 0010000 3 *crdno fvcahs 

0091101 001000 2 

0091201 102 4.20+6 0.0 0.0 0.0 0.0 1 

0091202 102 4.20+6 1.0 0.0 0.0 0.0 3 

0091300 1 

0091301 0.0 0.0 0.0 2 

0100000 sjl0 sngljun *crdno from to area floss rloss fvcahs 

0100101 009020004 011010001 0.0 0.35 0.85 001100 

0100201 0 0.0 0.0 0.0 

0110000 upplenm pipe *component no v.1 1,upper plenum dh=0.102 m 

0110001 11 

0110101 8.17-311 

0110301 0.42 1, 0.50 2, 0.6 3, 0.70 4, 

0110302 1.0 10, 0.29 11 

0110601 0.0 1, 90.0 11 

0110801 5.0-5 0.102 11 

0110901 1.151.151 

0110902 0.0 0.0 10 

*crdno tlpvbfe 

0111001 0010000 11 

*crdno fvcahs 

0111101 001000 10 

0111201 102 4.20+6 1.0 0.0 0.0 0.0 11 

01113001 

0111301 0.0 0.0 0.0 10 

*HOT LEG MODEL and STEAM GENERATOR TUBES 

SIMULATOR,components no sjl2,v.1 4 

0120000 sjl 2 sngljun 

*crdno from to area floss rloss fvcahs 

0120101 011100002 014000000 0.0 0.85 1.0 001100 

0120201 0 0.0 0.0 0.0 

0140000 hotleg pipe *component no v.14, hot leg and sg tubes simulator 

0140001 14 

0140101 0.0033183 14 

0140301 1.0 1, 1.85 5, 1.0 7, 2.0 14 

*0140301 1.0 1, 1.85 5, 1.5 6, 2.0 14 

0140601 1.0 7, 1.0 14 

0140801 5.0-5 0.065 14 

0140901 0.5 0.5 1 

0140902 0.0 0.0 4

D-3
0140903 0.5 0.5 5 

0140904 0.0 0.0 13 

*crdno tlpvbfe 

0141001 0010000 14 *crdno fvcahs 

0141101 001000 13 

0141201 102 4.20+6 1.0 0.0 0.0 0.0 14 

0141300 1 

0141301 0.0 0.0 0.0 13

0150000 sj15 sngljun 

*crdno from to area floss rloss fvcahs 

"0150101 106010000 016000000 0.0 0.0 0.0 001100 

0150101 014010000 016000000 0.0 0.0 0.0 001100 

0150201 0 0.0 0.0 0.0 

0160000 pressure tmdpvol 'crdno area lenght volume h.ang v.ang elev rgh dhyd pvbfe 

0160101 0.2525 3.2 0.0 0.0 0.0 0.0 5.0-5 0.0 00000 

01602002 

0160201 0.0 4.20+6 1.0 

TDOWNCOMER MODEL, components no sjl 01,v.1 02,sjl 03,v.1 04

1010000 sjl01 sngljun *crdno from to area floss rloss fvcahs 

1010101 001010001 102010001 3.49-4 0.5 0.5 001100 

1010201 0 0.0 0.0 0.0 

1020000 downcoml pipe *component no v.102 dh=0.080 m 1020001 32 

1020101 0.0050265 32 

1020301 0.25 30, 0.2 31, 0.23 32 

1020601 90.32 

1020801 5.0-5 0.08 32 

1020901 0.0 0.031 

*crdno tlpvbfe 

1021001 0010000 32 

*crdno fvcahs 

1021101 001000 31 

*1021201 1034.20+6 516.0 0.0 0.0 0.0 1 

1021201 102 4.20+6 0.5 0.0 0.0 0.0 1 

*1021202 102 4.20+6 0.8 0.0 0.0 0.0 2 

1021203 102 4.20+6 1.0 0.0 0.0 0.0 32 

10213001 

1021301 0.0 0.0 0.0 31 

1030000 sj103 sngljun 

*crdno from to area floss rloss fvcahs 

1030101 102310003 104010001 0.0 0.5 0.5 001100 

1030201 0 0.0 0.0 0.0 

1040000 downcom2 pipe *component v.104 dh=0.073 m 

1040001 11 

1040101 0.0041854 4 

1040102 0.00721 8, 0.00488 9, 0.0076 11 

1040301 0.38 1, 0.35 2, 0.8 3, 0.7925 4, 

1040302 0.9 5, 1.25 7, 1.29 8, 

1040303 1.07 9, 0.928856013 10, 0.29 11 

1040601 0.0 1, 45.0 2, 90.0 11

1040801 5.0-5 0.073 4 

1040802 5.0-5 0.067 8,5.0-5 0.0299 9,5.0-5 0.05288 11 

1040901 0.07 0.07 2 

1040902 0.00 0.00 3 

1040903 0.52 0.20 4 

1040904 0.00 0.00 7 

1040905 0.16 0.24 8 

1040906 0.24 0.16 9 

1040907 0.00 0.00 10 

*crdno tlpvbfe 

1041001 0010000 11 *crdno fvcahs 

1041101 001000 10 

*1041201 103 4.20+6 489.0 0.0 0.0 0.0 03 

*1041202 102 4.20+6 1.0 0.0 0.0 0.0 04 

1041203 102 4.20+6 1.0 0.0 0.0 0.0 11 

10413001 

1041301 0.0 0.0 0.0 10

1050000 sjl 05 sngljun .crdno from to area floss rloss fvcahs 

1050101 104100002 106010001 0.0 0.5 0.5 001100 

1050201 0 0.0 0.0 0.0 -------------------------------------------------------.

'Cold leg model and steam generator tubes simulator,component no 106 

1060000 cold pipe 

1060001 6 

1060101 0.0033183 6 

1060301 1.39 5,1.5 6 

1060601 1.0 6 

*1060601 0.3716971 6 

1060801 5.0-5 0.065 6 

1060901 0.0 0.0 4 

1060902 0.5 0.5 5 

*crdno tlpvbfe 

1061001 0010000 6 

*crdno fvcahs 

1061101 001000 5 

1061201 102 4.20+6 1.0 0.0 0.0 0.0 6 

1061300 1 

1061301 0.0 0.0 0.0 5

1070000 sjl07 sngljun *crdno from to area floss rloss fvcahs 

1070101 106010000 014070003 0.0 0.1 0.1 001100 

1070201 0 0.0 0.0 0.0

*HEAT STRUCTURE 

10011000 22 3 2 0 0.0325 

1001110001 

10011101 1 0.035 1 0.0375 

10011201 1 2 

10011301 0.0 2 

10011401 516.2 3 

10011501 001010000 10000 1 1 0.425 4 

10011502 001050000 10000 1 1 0.4 8 

10011503 001090000 10000 1 1 0.355 18 

10011504001190000 10000 1 1 0.422 

10011601 -3 0 3004 1 0.425 4 

10011602 -3 03004 1 0.48 

10011603 -3 0 3004 1 0.355 18

D-4
10011604 -3 0 3004 1 0.422 

10011701 0 0.0 0.0 0.0 22 

10011801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 22 

10012000 10 3 2 0 0.01 

1001210001 

10012101 1 0.0125 1 0.015 

10012201 1 2 

10012301 0.02 

10012401 516.03 

10012501 001230000 10000 1 1 0.7 10 

10012601 -3 0 3005 1 0.7 10 

10012701 0 0.0 0.0 0.0 10 

10012801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 10 

10013000 37 3 2 0 0.0325 

10013100 0 1 

10013101 1 0.035 1 0.0375 

10013201 1 2 

10013301 0.0 2 

100134000 

10013401 516.2 3 

10013501 001330000 10000 1 1 0.43 

10013502 001360000 10000 1 1 0.355 13 

10013503 001460000 10000 1 1 0.35533 

10013505 001500000 10000 1 1 0.37537 

10013601 -3 0 3004 1 0.43 

10013602 -3 0 3004 1 0.355 13 

10013603 -3 0 3004 1 0.355 33 

10013605 -3 0 3004 1 0.375 37 

10013701 0 0.0 0.0 0.037 

10013801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 37 

10212000 5 3 2 0 0.25 

1021210001 

10212101 1 0.3 1 0.35 

10212201 1 2 

10212301 0.0 2 

10212401 516.2 3 

10212501 021010000 00000 1 1 0.09 1 

10212502 021020000 00000 1 1 0.08 2 

10212503 021030000 00000 1 1 0.05 3 

10212504 021040000 10000 1 1 0.05 5 

10212601 -3 0 3006 1 0.09 1 

10212602 -3 0 3006 1 0.08 2 

10212603 -3 0 3006 1 0.05 3 

10212604 -3 0 3006 1 0.05 5 

10212701 0 0.0 0.0 0.0 5 

10212801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 5 

10211000 5 3 2 0 0.11 

1021110001 

10211101 1 0.12 1 0.13 

10211201 12 

10211301 0.0 2 

10211401 526.4 3 

10211501 02302000000000 1 1 0.091 

10211502 023030000 00000 1 1 0.082 

10211503 023040000 00000 1 1 0.053 

10211504 023050000 10000 1 1 0.055 

10211601 021010000 00000 1 1 0.091 

10211602 021020000 00000 1 1 0.082 

10211603 021030000 00000 1 1 0.053 

10211604 021040000 10000 1 1 0.055 

10211701 0 0.0 0.0 0.0 5 

10211801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 5' 

10211901 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 5 

10071000 20 7 2 0 0.00297 

1007110001 

10071101 1 0.00325 1 0.0035 1 0.00375 1 0.004 1 0.00425 1 0.0045 

10071201 1 6 

10071301 1.6

10071401 526.4 7 

10071501 0 0 0 1 2.375 20 

10071601 007010000 10000 110 1 2.375 20 

10071701 001 0.05 0.0 0.0 20 

10071900 1 

10071901 0.01346 0.0625 2.4375 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 1 

10071902 0.01346 0.1875 2.3125 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 2 

10071903 0.01346 0.3125 2.1875 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 3 

10071904 0.01346 0.4375 2.0625 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 4 

10071905 0.01346 0.5625 1.9375 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 5 

10071906 0.01346 0.6875 1.8125 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 6 

10071907 0.01346 0.8125 1.6875 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 7 

10071908 0.01346 0.9375 1.5625 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 8 

10071909 0.01346 1.0625 1.4375 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 9 

10071910 0.01346 1.1875 1.0125 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 10 

10071911 0.01346 1.3125 1.1875 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 11 

10071912 0.01346 1.4375 1.0625 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 12 

10071913 0.01346 1.5625 0.9375 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 13 

10071914 0.01346 1.6875 0.8125 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 14 

10071915 0.01346 1.8125 0.6875 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 15 

10071916 0.01346 1.9375 0.5625 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 16 

10071917 0.01346 2.0625 0.4375 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 17 

10071918 0.01346 2.1875 0.3125 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 18 

10071919 0.01346 2.3125 0.1875 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 19 

10071920 0.01346 2.4375 0.0625 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 20 

10072000 20 14 2 0 0.031 

100721000 1 

10072101 1 0.032 1 0.033 1 0.034 1 0.035 1 0.036 1 0.037 

10072102 1 0.038 1 0.039 1 0.040 

10072103 1 0.041125 1 0.04225 1 0.043375 1 0.0445 

10072201 29 113 

10072301 0.013 

10072401 526.4 14 

10072501 007010000 10000 1 1 0.125 20 

10072601 005010000 10000 1 1 0.125 20 

10072701 0 0.0 0.0 0.0 20 

10072801 0.0586 15.0 15.0 0.0 0.0 0.0 0.0 1.0 20 

10072901 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 20 

10052000 20 3 2 0 0.0955 

1005210001 

10052101 1 0.1045 1 0.1095 

100522011 2 

10052301 0.02 

10052401 526.43 

10052501 005010000 10000 1 1 0.125 20 

10052601 -3 0 3006 1 0.125 20 

10052701 0 0.0 0.0 0.0 20 

10052801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 20 

10091000 1 2 2 0 0.037 

1009110001 

10091101 1 0.043 

10091201 1 1 

10091301 0.0 1 

10091401 526.42 

10091501 007210000 10000 1 1 0.1 1 

10091601 009010000 10000 1 1 0.1 1 

10091701 0 0.0 0.0 0.0 1 

10091801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 1 

10091901 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 1 

10092000 3 3 2 0 0.15 

10092100 0 1 

10092101 1 0.161 1 0.172 

10092201 1 2 

10092301 0.02 

10092401 526.43 

10092501 009010000 10000 1 1 0.10 1 

10092502 009020000 10000 1 1 0.05 2 

10092503 009030000 10000 1 1 0.10 3 

10092601 -3 0 3006 1 0.10 1

D-5
10092602 -3 0 3006 1 0.05 2 

10092603 -3 0 3006 1 0.10 3 

10092701 0 0.0 0.0 0.0 3 

10092801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 3 

10111000 11 3200.061 

1011110001 

10111101 1 0.067 1 0.073 

10111201 12 

10111301 0.02 

10111401 526.4 3 

10111501 011010000 0 1 1 0.42 1 

10111502 011020000 0 1 1 0.32 

10111503 011030000 0 1 1 0.513 

10111504 011030000 0 1 1 0.74734 4 

10111505 011040000 10000 1 1 1.00 10 

10111506 011110000 10000 1 1 0.29 11 

10111601 -3 0 3008 1 0.421 

10111602 -3 0 3008 1 0.32 

10111603 -3 0 3008 1 0.51 3 

10111604 -3 0 3008 1 0.747344 

10111605 -3 0 3008 1 1.010 

10111606 -3 03008 1 0.29 11 

10111701 00.00.00.011 

10111801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 11 

10141000 143 2 0 0.0325 

1014110001 

10141101 1 0.035 1 0.0375 

10141201 1 2 

10141301 0.0 2 

10141401 526.4 3 

10141501 014010000 10000 1 1 1.0 1 

10141502 014020000 10000 1 1 1.85 5 

10141503 014040000 10000 1 1 1.0 7 

10141504 014070000 10000 11 2.0 14 

10141601 -3 0 3004 1 1.0 1 

10141602 -3 0 3004 1 1.85 5 

10141603 -3 0 3009 1 1.0 7 

10141604 -3 0 3004 1 2.0 14 

10141701 0 0.0 0.0 0.0 14 

10141801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 14 

11022000 32 4 2 0 0.04 

1102210001 

11022101 1 0.0475 1 0.055 

11022102 1 0.0625 

110222012 1 2 2 1 3 

11022301 0.0 3 

11022401 526.4 4 

11022501 102010000 10000 1 1 0.25 30 

11022502 102020000 10000 1 1 0.2 31 

11022503 102050000 10000 1 1 0.23 32 

11022601 -3030071 0.25 30 

11022602 -3 0 3007 1 0.2 31 

11022603 -3 0 3007 1 0.2332 

11022701 0 0.0 0.0 0.0 32 

11022801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 32 

11041000 4 3 2 0 0.0365 

1104110001 

11041101 1 0.0405 1 0.0445 

11041201 1 2 

11041301 0.0 2 

11041401 526.4 a 

11041501 104010000 0 1 1 0.38 1 

11041502 104020000 0 1 1 0.35 2 

11041503 104030000 10000 1 1 0.8 3 

11041504 104030000 10000 1 1 0.7713 4 

11041601 -3 0 3008 1 0.38 1 

11041602 -3 0 3008 1 0.35 2 

11041603 -3 0 3008 1 0.8 3 

11041604 -3 0 3008 1 0.7713 

4

11041701 0 0.0 0.0 0.0 4 

11041801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 4 

11042000 7 3 2 0 0.051 

1104210001 

11042101 1 0.054 1 0.057 

11042201 1 2 

11042301 0.0 2 

11042401 526.4 3 

11042501 104050000 0 1 1 0.9 1 

11042502 104060000 10000 1 1 1.25 3 

11042503 104080000 0 1 1 1.297 4 

11042504 104090000 0 1 1 1.075 

11042505 104100000 0 1 1 0.795 6 

11042506 104110000 0 1 1 0.29 7 

11042601 -3 0 3008 1 0.91 

11042602 -3 0 3008 1 1.253 

11042603 -3 0 3008 1 1.2974 

11042604 -3 0 3008 1 1.075 

11042605 -3 0 3008 1 0.7956 

11042606 -3 0 3008 1 0.297 

11042701 0 0.0 0.0 0.0 7 

11042801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 7 

11061000 6 3 2 0 0.0325 

1106110001 

11061101 1 0.035 1 0.0375 

11061201 1 2 

11061301 0.0 2 

11061401 526.4 3 

11061501 106010000 10000 1 1 1.395 

11061502 106030000 0 1 1 1.5 6 

11061601 -3 0 3004 1 1.39 5 

11061602 -3 0 3009 1 1.5 6 

11061701 0 0.0 0.0 0.0 6 

11061801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 6 

*general tables 

***matereal 

20100100 tbl/fctn 1 1 

20100101 295.0 15. 

20100102 400.0 16. 

20100103 500.0 18. 

20100104 600.0 20. 

20100105 700.0 21. 

20100106 800.0 23. 

20100107 900.0 25. 

20100108 1000.0 26. 

20100109 1100.0 28. 

20100110 1200.0 29. 

20100151 295.0 3.686+6 

20100152 400.0 3.686+6 

20100153 500.0 3.801+6 

20100154 600.0 3.874+6 

20100155 700.0 3.955+6 

20100156 800.0 3.991+6 

20100157 900.0 4.039+6 

20100158 1000.0 4.043+6 

20100159 1100.0 4.113+6 

20100160 1200.0 4.115+6 

20100200 tbVfctn 1 1 

20100201 295.0 2.25 

20100202 400.0 1.8 

20100203 500.0 1.65 

20100204 600.0 1.5 

20100205 700.0 1.35 

20100206 800.0 1.2 

20100207 900.0 1.112 

20100251 295.0 2.128+6 

20100252 400.0 2.408+6 

20100253 500.0 2.604+6 

20100254 600.0 2.772+6 

20100255 700.0 2.940+6

D-6
20100256 800.0 3.080+6 

20100257 900.0 3.220+6

20100300 s-steel 

**heat source 

20200100 power 0 1. 1000. 

20200101 000.00 0.0 

20200102 100.00 0.0 

20200103 200.00 9.52 

**out temperature 

20200300 temp 0 1.0 1.0 0.0 

20200301 0.0 300.0 

*diam 75 

20200400 htc-t 0 1.0 2.3 

20200401 000.0 0.0 

20200402 100.0 0.0 

20200403 200.0 3.0 

*diam 28 

20200500 htc-t 0 1.0 4.6 

20200501 000.0 0.0 

20200502 100.0 0.0 

20200503 200.0 2.9 

*diam can 1 

20200600 htc-t 0 1.0 2.0 

20200601 000.0 0.0 

20200602 100.0 0.0 

20200603 200.0 3.0 

*diam can 2 

20200700 htc-t 0 1.0 2.4 

20200701 000.0 0.0 

20200702 100.0 0.0 

20200703 200.0 3.0 

*diam vks 1 2 

20200800 htc-t 0 1.0 2.3 

20200801 000.0 0.0 

20200802 100.0 0.0 

20200803 200.0 3.0 

*diam 75 (top) 

20200900 htc-t 0 1.0 4.3 

20200901 000.0 0.0 

20200902 100.0 0.0 

20200903 200.0 3.00 

.*end of data set 

Input deck 1 

Base case transient restart input deck listing of KS-1 test 35-1 

Maximum time step 0.01, restart time 0.0 s 

0000100 restart transnt *0000101 inp-chk 

0000102 si si 

0000103 970 cmpress 

0000202 365. 1.0-6 0.001 15003 200 100000 1000000 

0000203 600. 1.0-6 0.001 15003 200 1000000 1000000 

0150000 autleg delete 

0160000 cmpnstr delete 

.end data set 

Input deck 2 

Time step sensitivty restart input deck listing of KS-1 test 

Maximum time step 0.2s, restart time 0.0 s 

0000100 restart transnt *O000101 inp-chk 

0000102 si si 

0000103 970 cmpress 

0000202 365. 1.0-6 0.2 15003 10 100000 1000000

0000203 600. 1.0-6 0.2 15003 10 1000000 1000000 

0150000 autleg delete 

0160000 cmpnstr delete 

end data set 

Input deck 3 

Sensitivty Tw(z)exp variation restart input deck listing of KS-1 

test 35-1 

Maximum time step dt=0.0Is, restart time 365.0 s. 

Using base case input deck, dT=0.01 s. 

0000100 restart transnt *0000101 inp-chk 

0000102 si si 

0000103 4483 cmpress 

* I 

0000203 600. 1.0-6 0.01 15003 200 1000 10000 

10071000 20 7 2 0 0.00297 

100711000 1 

10071101 1 0.00325 1 0.0035 1 0.00375 1 0.004 1 0.00425 1 0.0045 

10071201 1 6 

10071301 1.6 

*10071401 526.4 7 

10071400-1 

10071401 521.0 521.0 521.0 521.0 521.0 521.0 521.0 

10071402 521.0 521.0 521.0 521.0 521.0 521.0 521.0 

10071403 521.0 521.0 521.0 521.0 521.0 521.0 521.0 

10071404 521.0 521.0 521.0 521.0 521.0 521.0 521.0 

10071405 640.0 640.0 640.0 640.0 640.0 640.0 640.0 

10071406 660.0 660.0 660.0 660.0 660.0 660.0 660.0 

10071407 680.0 680.0 680.0 680.0 680.0 680.0 680.0 

10071408 700.0 700.0 700.0 700.0 700.0 700.0 700.0 

10071409 725.0 725.0 725.0 725.0 725.0 725.0 725.0 

10071410 719.0 719.0 719.0 719.0 719.0 719.0 719.0 

10071411 719.0 719.0 719.0 719.0 719.0 719.0 719.0 

10071412 743.0 743.0 743.0 743.0 743.0 743.0 743.0 

10071413 742.0 742.0 742.0 742.0 742.0 742.0 742.0 

10071414 731.0 731.0 731.0 731.0 731.0 731.0 731.0 

10071415 743.0 743.0 743.0 743.0 743.0 743.0 743.0 

10071416 751.0 751.0 751.0 751.0 751.0 751.0 751.0 

10071417 695.0 695.0 695.0 695.0 695.0 695.0 695.0 

10071418 742.0 742.0 742.0 742.0 742.0 742.0 742.0 

10071419 734.0 734.0 734.0 734.0 734.0 734.0 734.0 

10071420 670.0 670.0 670.0 670.0 670.0 670.0 670.0 

10071501 0 0 0 1 2.37520 

10071601 007010000 10000 110 1 2.375 20 

10071701 001 0.05 0.0 0.0 20 

100719001 

10071901 0.01346 0.0625 2.4375 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 1 

10071902 0.01346 0.1875 2.3125 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 2 

10071903 0.01346 0.3125 2.1875 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 3 

10071904 0.01346 0.4375 2.0625 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 4 

10071905 0.01346 0.5625 1.9375 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 5 

10071906 0.01346 0.6875 1.8125 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 6 

10071907 0.01346 0.8125 1.6875 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 7 

10071908 0.01346 0.9375 1.5625 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 8 

10071909 0.01346 1.0625 1.4375 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 9 

10071910 0.01346 1.1875 1.0125 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 10 

10071911 0.01346 1.3125 1.1875 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 11 

10071912 0.01346 1.4375 1.0625 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 12 

10071913 0.01346 1.5625 0.9375 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 13 

10071914 0.01346 1.6875 0.8125 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 14 

10071915 0.01346 1.8125 0.6875 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 15 

10071916 0.01346 1.9375 0.5625 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 16 

10071917 0.01346 2.0625 0.4375 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 17 

10071918 0.01346 2.1875 0.3125 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 18 

10071919 0.01346 2.3125 0.1875 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 19 

10071920 0.01346 2.4375 0.0625 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 20

D-7
.end data set 

Input deck 4 

Sensitivty Tw(z)exp variation restart input deck listing of KS-1 test 

35-1 

Maximum time step dt=O.Ols, restart time 365.0 s. 

Using time step sensitivity case input deck, dT=0.2 s. 

0000100 restart transnt 

*0000101 inp-chk 

0000102 si si 

0000103 36500 cmpress 

0000203 600. 1.0-6 0.01 15003 200 1000 10000 

10071000 20 7 2 0 0.00297 

1007110001 

10071101 1 0.00325 1 0.0035 1 0.00375 1 0.004 1 0.00425 1 0.0045 

10071201 1 6 

10071301 1.6 

*10071401 526.4 7 

10071400-1 

10071401 521.0 521.0 521.0 521.0 521.0 521.0 521.0 

10071402 521.0 521.0 521.0 521.0 521.0 521.0 521.0 

10071403 521.0 521.0 521.0 521.0 521.0 521.0 521.0 

10071404 521.0 521.0 521.0 521,0 521.0 521.0 521.0 

10071405 640.0 640.0 640.0 640.0 640.0 640.0 640.0 

10071406 660.0 660.0 660.0 660.0 660.0 660.0 660.0 

10071407 680.0 680.0 680.0 680.0 680.0 680.0 680.0 

10071408 700.0 700.0 700.0 700.0 700.0 700.0 700.0 

10071409 725.0 725.0 725.0 725.0 725.0 725.0 725.0 

10071410 719.0 719.0 719.0 719.0 719.0 719.0 719.0 

10071411 719.0 719.0 719.0 719.0 719.0 719.0 719.0 

10071412 743.0 743.0 743.0 743.0 743.0 743.0 743.0 

10071413 742.0 742.0 742.0 742.0 742.0 742.0 742.0 

10071414 731.0 731.0 731.0 731.0 731.0 731.0 731.0 

10071415 743.0 743.0 743.0 743.0 743.0 743.0 743.0 

10071416 751.0 751.0 751.0 751.0 751.0 751.0 751.0 

10071417 695.0 695.0 695.0 695.0 695.0 695.0 695.0 

10071418 742.0 742.0 742.0 742.0 742.0 742.0 742.0 

10071419 734.0 734.0 734.0 734.0 734.0 734.0 734.0 

10071420 670.0 670.0 670.0 670.0 670.0 670.0 670.0 

10071501 0 0 0 1 2.375 20 

10071601 007010000 10000 110 1 2.375 20 

10071701 001 0.05 0.0 0.0 20 

100719001 

10071901 0.01346 0.0625 2.4375 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 1 

10071902 0.01346 0.1875 2.3125 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 2 

10071903 0.01346 0.3125 2.1875 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 3 

10071904 0.01346 0.4375 2.0625 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 4 

10071905 0.01346 0.5625 1.9375 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 5 

10071906 0.01346 0.6875 1.8125 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 6 

10071907 0.01346 0.8125 1.6875 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 7 

10071908 0.01346 0.9375 1.5625 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 8 

10071909 0.01346 1.0625 1.4375 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 9 

10071910 0.01346 1.1875 1.0125 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 10 

10071911 0.01346 1.3125 1.1875 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 11 

10071912 0.01346 1.4375 1.0625 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 12 

10071913 0.01346 1.5625 0.9375 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 13 

10071914 0.01346 1.6875 0.8125 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 14 

10071915 0.01346 1.8125 0.6875 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 15 

10071916 0.01346 1.9375 0.5625 0.0 0.0 0.0 0.0 1.0 0,125 1.42 1.0 16 

10071917 0.01346 2.0625 0.4375 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 17 

10071918 0.01346 2.1875 0.3125 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 18 

10071919 0.01346 2.3125 0.1875 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 19 

10071920 0.01346 2.4375 0.0625 0.0 0.0 0.0 0.0 1.0 0.125 1.42 1.0 20 

.end data set

D-8
NRC FORM 336 UA. NUCLEAR REGULATORY COMMISSION 1. REPORT NUMBER 

(2-89) (Assigned by NRC, AMd Vol., Supp., Rev., 

NRCM 1102, and Addendum Numbers, If any.) 

3=, 30 BIBUGRAPHIC DATA SHEET 

(See inshruetima on the reverse) 

2. TITLE AND SUBTITLE NUREGAIA-0169 

Analysis of the KS-1 Experimental Data on the Behavior of the Heated Rod 

Temperatures in the Partially Uncovered WER Core Model Using RELAP5/MOD3.2 3. DATE REPORT PUBLISHED 

MONTHYEAR 

November 1999 

4. FIN OR GRANT NUMBER 

5. AUTHOR(S) 6. TYPE OF REPORT 

V.A. Vinogradov, A.Y. Balykin Technical 

7. PERIOD COVERED (inclusive Deots) 

8. PERFORMING ORGANIZATION - NAME AND ADDRESS (If NRC, provide Division, Office or Region, U.S. Nuclear Regulatory Commission, and mailing address; dfconfracto, 

provide name and mailing address.) 

Nuclear Safety Institute 

Russian Research Center "Kurchatov Institute" 

123182, Moscow 

Russia 

9. SPONSORING ORGANIZATION - NAME AND ADDRESS (1f NRC, type 'Same as above, if confrac, provide NRC Division, Office or Region, U.S. Nuclear Regulatory Commission, 

and mailing address.) 

Division of System Analysis and Regulatory Effectiveness 

Office of Nuclear Regulatory Research 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001 

10. SUPPLEMENTARY NOTES 

11. ABSTRACT (2r" words orlass) 

This report has been prepared as a part of the Agreement on Research Participation and Technical Exchange under the 

International code application and Maintenance Program. KS-1 Test 35-1 data on the behavior of the heated rod temperatures in 

the partially uncovered WER Core model were simulated with RELAP5/MOD3.2 to assess the code, especially its non-equilibrium 

(unequal phase temperatures) heat t transfer models for modeling phenomena in partially uncovered core under Small Break 

LOCA conditions. The test has been carded out at experimental section KS-1 of the test facility KS (RRC KI) in 1991. KS-1 

experimental section (WER Loop model) includes models of all main elements of WER type reactor, loop hot leg model and cold 

leg simulator, and also horizontal SG tube bundle simulator with passive heat removal. Core model consists of 19 electrically 

heated rod simulators with diameter 9 mm and height 2.5m. Test 35-1 models thermal and hydraulic processes during reflux 

condenser mode in primary circuit with low mixture level in partially uncovered WER core under conditions of small residual heat 

power, middle pressure and counter current flow in the core. First a study of the effect of the hydraulic nodalization to the code 

calculations was performed using different number of hydraulic volumes for Core model. after the choice of proper nodalization 

and maximum user-specified time step, base case calculations were done for the test The differences between code predictions 

for behavior of rod simulator temperatures along the height of Core model and test data are described and analyzed. Sensit"ty 

studies were carried out to investigate the effects of modeling on the behavior of the rod simulator temperatures along the height of 

Core model.

12. KEY WORDSIDESCRIPTORS (List wods or plwases that will assist reserchers in locating fth reporQ 13. AVAILABILITY STATEMENT 

RELAP5/MOD3.2 unlimited 

Rod Temperatures 14. SECURITY CLASSIFICATION 

WER (This Page) 

unclassified 

(This Repod) 

unclassified 

15. NUMBER OF PAGES 

16. PRICE

NRC FORM 335 (2.89)
Federal Recycling Program
NUREG/IA-0169 ANALYSIS OF KS-1 EXPERIMENTAL DATA ON THE BEHAVIOR OF THE HEATED ROD 

TEMPERATURES IN THE PARTIALLY UNCOVERED VVER CORE MODEL USING RELAP5/MOD3.2

NOVEMBER 1999

UNITED STATES 

NUCLEAR REGULATORY COMMISSION 

WASHINGTON, DC 20555-0001

SPECIAL STANDARD MAIL 

POSTAGE AND FEES PAID 

USNRC 

PERMIT NO. G-67

OFFICIAL BUSINESS 

PENALTY FOR PRIVATE USE, $300