NUREG/IA-0208

International 

Agreement Report 

Analysis of the VTI Test Data on the 

Behavior of the Heated Rod Temperatures 

in the Partially Uncovered VVER-440 

Core Model Using RELAP5/MOD3.2.2 

Gamma 

Prepared by: 

V.A. Vinogradov, and A.Y. Balykin 

Russian Research Center "Kurchatov Institute" 

Kurchatov Square 1 

123182, Moscow, Russia 

Office of Nuclear Regulatory Research 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001 

July 2002 

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-0208

a Agreement International Report 

Analysis of the VTI Test Data on the 

Behavior of the Heated Rod Temperatures 

in the Partially Uncovered VVER-440 

Core Model Using RELAP5/MOD3.2.2 

Gamma 

Prepared by: 

V.A. Vinogradov, and A.Y. Balykin 

Russian Research Center "Kurchatov Institute" 

Kurchatov Square 1 

123182, Moscow, Russia 

Office of Nuclear Regulatory Research 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001 

July 2002 

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. 

VTI test data on the behavior of the heated rod temperatures in the partially uncovered VVER-440 

core model were simulated with RELAP5/MOD3.2.2GAMMA to assess the code, especially its 

heat transfer models for modeling phenomena in the partially uncovered core under Small Break 

LOCA conditions. This problem addresses the phenomena of high importance to VVER-440 safety. 

Series of the experiments have been carried out in the VVER-440 loop model at the VTI Test 

Facility which are directly related to this issue. Two tests conducted in the stationary conditions 

with the transition mode of a steam flow in the core channel were chosen for the assessment 

calculations with the code. 

Experimental VVER-440 loop model includes the models of all the main elements of a reactor, 

loop's hot leg model and cold leg simulator, and also a steam generator simulator with an active 

heat removal. The fuel assembly model consists of 19 electrically heated rod simulators of 9.1 mm 

outer diameter and 2.5 m heated height. The rod simulators are composed in the rod bundle in a 

hexagonal array with a pitch equal 12.2 mm (P/D=l.34). 

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

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

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

differences between the code predictions for the behavior of rod's wall temperatures and test data 

are described and analyzed. 

Sensitivity studies were carried out to investigate the influence of an increase in the calculated 

coefficients of heat transfer from the heated rods to a steam flow on the axial distribution of rod's 

wall temperatures in the uncovered part 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. DESCRIPTION OF VTI TEST FACILITY 3 

2.1. Description of the VVER-440 loop model at VTI Test Facility 3 

2.2. Main components characteristics 5 

2.3. Measurements and errors 7 

3. DESCRIPTION OF THE TESTS 9 

3.1. VVER specific phenomena investigated in the tests 9 

3.2. Experiment performance technique 10 

3.3. Initial and boundary conditions 12 

3.4. Experimental Data used 14 

4. DESCRIPTION OF RELAP5 MODEL AND BASE CASE INPUT DECK 

FOR THE TESTS 17 

4.1. Code description 17 

4.2. RELAP5/MOD3.2.2 model and Input Deck development 17 

4.3. Method of computer modeling of the experiments 20 

5. RESULTS OF THE CODE ASSESSMENT 25 

5.1. Nodalization, including variations from base case 25 

5.2. Base case results for test 7.12.15.4, comparisons to VTI test data 

and conclusions 26 

5.3. Base case results for test 8.6.3.2, comparisons to VTI test data and conclusions 33 

6. SENSITIVITY STUDIES 38 

7. RUN STATISTICS 46 

8. SUMMARY OF CONCLUSIONS 47 

REFERENCES 48 

iv

I I
Appendix A Original Date Plots from the Tests A-1 

Appendix B Base Case Results for Test 7.12.15.4 B-1 

Appendix C Base Case Results for Test 8.6.3.2 C-1 

Appendix D Sensitivity Studies Results D-1 

Appendix E: Base Case input deck listing for Test 8.6.3.2 E-1 

LIST OF FIGURES 

Fig.2.1 Scheme of the VVER-440 loop model and measurements on VTI Test Facility 4 

Fig.2.2. Model of the VVER-440 fuel assembly. 6 

Fig.2.3. Scheme of location of the thermocouples along the FA model height [2]. 8 

Fig.3. 1. Experimental axial power distribution of the rod simulator's heater for test 

7.12.15.4. 16 

Fig.3.2. Experimental axial power distribution of the rod simulator's heater for test 

8.6.3.2. 16 

Fig.4. 1. Base case nodalization scheme of VVER-440 loop model at VTI Test 

Facility. 19 

Fig.5.1. Comparison of the axial profile of calculated rod's wall temperature TW 

(tical) and axial distribution of the measured rod's cladding temperatures TW (tOexp) 

for the initial time moment for test 7.12.15.4 at FA power W=16.8 kW and pressure 

Pup= 27.3 bar. 28 

Fig.5.2. Axial distribution of the calculated coefficients Hwl (t2cal) of heat transfer 

from the rods to a coolant in the upper part of the FA model for experiment 7.12.15.4. 31 

Fig.5.3. Comparison of the axial profile of calculated rod's wall temperature TW 

(tlcal) and axial distribution of measured rod's cladding temperatures TW (tOexp) for 

the initial time moment for test 8.6.3.2 at the FA power W=23 kW and pressure Pup= 

70.1 bar. 34 

Fig.5.4. Axial distribution of the calculated coefficients Hwl (t2cal) of heat transfer 

from the rods to a coolant in the upper part of the FA model for experiment 8.6.3.2. 36 

Fig.6.1. Comparison of the base case (Knwl=1 .0) and sensitivity case (KHwI=3.0) 

calculated axial profiles of rod's wall temperatures TW (tical) with the measured 

distribution of the rod's cladding temperatures for the initial steady state in the test 

7.12.15.4. 40 

Fig.6.2. Comparison of the base case (KHwI=l.0) and sensitivity case (KHwi=3.0)

V
calculated axial profiles of the rod's wall temperatures TW (tlcal) with the measured 

distribution of rod's cladding temperatures for the initial steady state in the test 

8.6.3.2. 41 

Fig. 6.3. The effect of the increase in the heat transfer coefficients Hwl (tcal) and of 

the implementation real axial profile of the rod simulators in the Restart input deck on 

the histories of the calculated rod's wall temperatures TW (tcal) in the FA uncovered 

part. 42 

Fig.6.4. Comparison of the base case (KHwv=l.0) and sensitivity case (KHWv=3.0) 

calculated axial distributions of the heat transfer coefficients Hwl (tlcal) in the 

uncovered part of the FA model for the test 7.12.15.4. 44 

Fig.6.5. Comparison of the base case (KHwl=l.0) and sensitivity case (KHWv=3.0) 

calculated axial distributions of the heat transfer coefficients Hwl (tlcal) in the 

uncovered part of the FA model for the test 8.6.3.2. 44 

Fig.7.1. Execution times (CPU TIME) of the main variant computation for test 

8.6.3.2. 46 

Fig.7.2. Integration step (DT) variations at the main variant computation for test 

8.6.3.2. 46 

Fig.A-1. Experimental core axial distribution of rod's wall temperatures for test 

7.12.15.4. A-2 

Fig.A-2. Experimental core axial distribution of rod's wall temperatures for test 

8.6.3.2. A-3 

Fig.B-1. Comparison of the calculated Pup (tcal) and measured Pup (texp) pressure 

histories in the upper plenum model in experiment 7.12.15.4 B-2 

Fig.B.-2. Calculated TF (tcal) water temperature history at the inlet of FA channel in 

experiment 7.12.15.4. B-2 

Fig.B-3. Comparison of the calculated GL (tcal), Gg (tcal) and measured G (texp) 

mass flow rate histories at the inlet of FA channel in experiment 7.12.15.4. B-3 

Fig.B-4. Comparison of the distributions of experimental qw (t0exp) and calculated 

qw (tIcal) specific heat fluxes from the outer surfaces of the rod simulators to a 

coolant on the FA height for the initial time moment in experiment 7.12.15.4. B-3 

Fig.B-5. Calculated TW (tcal) rod's wall temperatures histories in the upper, middle 

and bottom parts of the FA model in experiment 7.12.15.4. B-4 

vi
Fig.B-6. Comparison of the axial profile of calculated rod's wall temperature Tw 

(t2cal) in the FA model and axial distribution of measured rod's cladding 

temperatures for test 7.12.15.4. B-5 

Fig.B-7. Histories of the calculated coefficients Hwl(tcal) of heat transfer from the 

rods to a vapor in the uncovered part of the FA model in experiment 7.12.15.4. B-5 

Fig.B-8. Axial distribution of the calculated coefficients Hwl(t2cal) of heat transfer 

from the rods to a coolant for experiment 7.12.15.4. B-6 

Fig.B-9. Calculated void fractions histories in the upper part of FA channel in 

experiment 7.12.15.4. B-6 

Fig.B-10. Calculated Vg (tcal) vapor velocities histories in the upper part of FA 

channel in experiment 7.12.15.4. B-7 

Fig.B-11. Calculated axial distribution of the void fractions in the FA channel in 

experiment 7.12.15.4. B-7 

Fig.B-12. Calculated axial distribution of the vapor velocities in the FA channel at 

pressure Pup=27.3 bar and FA power W=16.8 kW in experiment 7.12.15.4. B-8 

Fig.B-13. Axial distribution of the calculated vapor temperatures Tg (x) in the 

uncovered part of FA channel for the test 7.12.15.4. B-8 

Fig.C-1. Comparison of the calculated Pup (teal) and measured Pup (texp) pressure 

histories in the upper plenum model in experiment 8.6.3.2. C-2 

Fig.C-2. Calculated TF(tcal) water temperature history at the inlet of FA channel in 

experiment 8.6.3.2. C-2 

Fig.C-3. Comparison of the calculated GL (teal), Gg (tcal) and measured G (texp) 

mass flow rate histories at the inlet of FA channel in experiment 8.6.3.2. C-3 

Fig.C-4. Comparison of the distributions of experimental qw (tOexp) and calculated 

qw (tlcal) specific heat fluxes from the outer surfaces of the rod simulators to a 

coolant on the FA height for the initial time moment in experiment 8.6.3.2. C-3 

Fig.C-5. Calculated TW (teal) rod's wall temperatures histories in the upper, middle 

and bottom parts of the FA model in experiment 8.6.3.2. C-4 

Fig.C-6. Comparison of the axial profile of calculated rod's wall temperature TW 

(t2cal) in the FA model and axial distribution of measured rod's cladding 

temperatures for test 8.6.3.2. C-5

vii
Fig.C-7. Histories of the calculated coefficients Hwl(tcal) of heat transfer from the 

rods to a vapor in the uncovered part of the FA model in experiment 8.6.3.2. C-5 

Fig.C-8. Core axial distribution of the calculated coefficients Hwl(t2cal) of heat 

transfer from the rods to a coolant for experiment 8.6.3.2. C-6 

Fig.C-9. Calculated void fractions histories in the upper part of FA channel in 

experiment 8.6.3.2. C-6 

Fig.C-10. Calculated Vg (tcal) vapor velocities histories in the upper part of FA 

channel in experiment 8.6.3.2. C-7 

Fig.C-11. Calculated axial distribution of the void fractions in the FA channel in 

experiment 8.6.3.2. C-7 

Fig.C-12. Calculated axial distribution of the vapor velocities in the FA channel at 

pressure Pup=27.3 bar and FA power W=16.8 kW in experiment 8.6.3.2. C-8 

Fig.C-13. Axial distribution of the calculated vapor temperatures Tg (x) in the 

uncovered part of FA channel for the test 8.6.3.2. C-8 

Fig.D-1. Comparison of the calculated Pup (tcal) and measured Pup (texp) pressure 

histories in the upper plenum model in experiment 7.12.15.4. D-2 

Fig.D-2. Comparison of the calculated GL (tcal), Gg (tcal) and measured G (texp) 

mass flow rate histories at the inlet of the FA channel in experiment 7.12.15.4. D-2 

Fig.D-3. Comparison of the distributions of experimental qw (tOexp) and calculated 

qw (tlcal) specific heat fluxes from the outer surfaces of the rod simulators to a 

coolant on the FA height for the initial time moment in experiment 7.12.15.4. D-3 

Fig.D-4. Axial distribution of the calculated vapor temperatures Tg (x) in the 

uncovered part of the FA channel at KHwl=3.0 for the test 7.12.15.4. D-3 

Fig.D-5. Calculated TW(tcal) rod's wall temperatures histories in the upper, middle 

and bottom parts of the FA model in experiment 7.12.15.4. D-4 

Fig.D-6. Comparison of the axial profile of calculated rod's wall temperature TW 

(tlcal) at Kmvl=3.0 in the FA model and axial distribution of measured rod's cladding 

temperatures for test 7.12.15.4. D-5 

Fig.D-7. Axial distribution of the calculated coefficients Hwl(t2cal) of heat transfer 

from the rods to a coolant at KHWI=3.0 in the upper part of the FA model for 

experiment 7.12.15.4. D-5

viii
Fig.D-8. Calculated core axial distribution of the void fractions in the FA channel in 

experiment 7.12.15.4. D-6 

Fig.D-9. Calculated core axial distribution of the vapor velocities in the FA channel at 

pressure Pup=27.3 bar and FA power W=16.8 kW in experiment 7.12.15.4. D-6 

Fig.D-10. Comparison of the calculated Pup (tcal) and measured Pup (texp) pressure 

histories in the upper plenum model in experiment 8.6.3.2. D-7 

Fig.D- 11. Comparison of the calculated GL (tcal), Gg (tcal) and measured G (texp) 

mass flow rate histories at the inlet of the FA channel in experiment 8.6.3.2. D-7 

Fig.D-12. Comparison of the distributions of experimental qw (tOexp) and calculated 

qw (tlcal) specific heat fluxes from the outer surfaces of the rod simulators to a 

coolant on the FA height for the initial time moment in experiment 8.6.3.2. D-8 

Fig.D-13. Axial distribution of the calculated vapor temperatures Tg (x) in the 

uncovered part of the FA channel at Knwl=3.0 for the test 8.6.3.2. D-8 

Fig.D-14. Histories of the calculated TW (tcal) rod's wall temperatures in the upper, 

middle and bottom of the FA model in experiment 8.6.3.2. D-9 

Fig.D-15. Comparison of the axial profile of calculated rod's wall temperature TW 

(t2cal) at KHw1=3.0 in the FA model and axial distribution of measured rod's cladding 

temperatures for test 8.6.3.2. D-10 

Fig.D-16. Axial distribution of the calculated coefficients Hwl(t2cal) of heat transfer 

from the rods to a coolant in the upper part of the FA model for experiment 8.6.3.2. D-10 

Fig.D-17. Calculated axial distribution of the void fractions in the FA channel in 

experiment 8.6.3.2. D-11 

Fig.D-18. Calculated axial distribution of the vapor velocities in the FA channel at 

pressure Pup=27.3 bar and FA power W=16.8 kW in experiment 8.6.3.2. D-11 

LIST OF TABLES 

Table 2.1. Parameters of the core model with VVER-440 fuel assembly model 5 

Table 2.2. List of measured parameters used in calculations and measurement errors 9 

Table 3.1.Parameters of the core model with VVER-440 fuel assembly model and 

VVER-440 fuel assembly 10 

Table 3.2. Initial values of determinative parameters for test 7.12.15.4 and test 8.6.3.2 

in steady regimes 14

ix
EXECUTIVE SUMMARY

VTI test data on the behavior of rod's cladding temperatures in the partially uncovered VVER-440 

core model were simulated with RELAP5/MOD3.2.2GAMMA to assess the code. These 

calculations were performed to evaluate the code prediction capability in modeling heat transfer 

phenomena in the partially uncovered core under specific conditions of VVER-440 type reactor 

during Small Break LOCA. 

Series of the tests have been carried out in the VVER-440 loop model at the VTI Test Facility 

which are directly related to this issue. Two tests were chosen for the code simulations of heat 

transfer phenomena occurring in the partially uncovered core during SB LOCA. 

Experimental VVER-440 loop model includes the models of all the main elements of a reactor, 

loop's hot leg model and cold leg simulator, and also a steam generator simulator with an active 

heat removal. The fuel assembly model consists of 19 electrically heated rod simulators of 9.1 mm 

outer diameter and 2.5 m heated height. The rod simulators are composed in the rod bundle in a 

hexagonal array with a pitch equal 12.2 mm (P/D=1.34). 

Special emphases were given to: 

* Hydrodynamics and heat transfer processes in the partially uncovered core model during steam

condensate natural circulation in the primary coolant system with small specific heat fluxes and 

medium pressures, and also in condition of absence of counter-current flow of phases in the 

uncovered part of the core; 

* Axial distributions of the heat transfer coefficients and rod's wall temperatures in the uncovered 

part of the fuel assembly model in the stationary conditions with the transition mode of a steam 

flow in the core channel. 

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

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

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

differences between the code predictions for the behavior of rod's wall temperatures and test data 

are described and analyzed, 

Sensitivity studies were carried out to investigate the influence of an increase in the calculated 

coefficients of heat transfer from the heated rods to a steam flow on the axial distribution of rod's 

wall temperatures in the uncovered part of core model. 

x

I I
Code results are presented as time-dependent curves. The results of comparison of the calculated 

and measured values of the determinative and determined parameters are a base for a conclusion 

about adequacy of the code simulation of the initial and boundary conditions, realizing in the test, 

and then about adequacy of the code simulation of a steady regime. 

The adequacy of the code modeling of heat transfer phenomena in the uncovered part of the core 

model has been estimated by comparison of the core axial profiles of the calculated and measured 

rod's cladding temperatures at the end of a steady regime. 

In this work some deficiencies of RELAP5/MOD3.2.2GAMMA in analyses of VTI test 7.12.15.4 

and test 8.6.3.2 could be identified, and the following conclusions can be drawn: 

* RELAP5/MOD3.2.2GAMMA and the base case methods of computer modeling of the 

experiments have provided adequate simulation of the initial and boundary conditions only for 

hydrodynamics, realized during the tests with steam-condensate natural circulation in the VVER

440 loop model. In these tests the transition mode of a steam flow is realized in the uncovered part 

of the FA model with corresponding Reynolds numbers Reg= Vg .Dh /vg = 1860 - 830. This mode 

is realized between laminar and turbulent modes of a steam flow in the uncovered part of the FA 

channel. 

o Shown is an insufficient code adequacy for the description of rod's wall temperatures behaviors in 

the uncovered part of the FA model. There are significant quantitative differences of the axial 

profiles of calculated and measured rod's wall temperatures in the uncovered part of the FA model 

in the base case calculations for these tests. 

The code over predicts rod's wall temperatures in the uncovered part of the FA model at the initial 

time moment, and then during "steady regime". The calculated rod's wall temperatures are much 

higher (up to - 150 K) than measured ones at the FA outlet. This is the main problem of the code 

for the base case calculations for these tests. 

* The sensitivity studies show, that the increase in calculated coefficients of heat transfer in the 

uncovered part of the FA model results in a reasonable adequacy of the code simulation of the 

initial and boundary conditions for both hydrodynamics and heat transfer process, realized in the 

uncovered part of the core model. Using fouling factor KHWl=3.0 the code reasonably describes the 

axial distributions of the rod's wall temperatures in the uncovered part of the FA model for the 

initial steady states, and then during the steady regimes in considered tests.

xi
NOMENCLATURE

W 

- power of the FA model, W, kW 

qw 

- heat flux, W/ 

m

2 , kW/m 2 

qw average 

- FA average heat flux, kW/ 

m2 

Pup 

- pressure at the upper plenum model outlet, bar 

Lm 

- mixture level in the FA channel, m 

TF 

- water temperature in the lower plenum model, K 

TW 

- rod's cladding temperature, K 

Ts 

- saturation temperature, K 

Tg 

- vapor temperature, K 

D 

- diameter, mm 

Dh 

- hydraulic diameter of the channel, mm 

De 

- heated equivalent diameter, mm 

P 

- rod pitch, mm 

Psg 

- spacer grid pitch, mm 

local hydraulic resistance coefficient 

G 

- mass flow rate at natural circulation in the loop, kg/s 

GL 

- liquid mass flow rate, kg/s 

Gg 

- vapor mass flow rate, kg/s 

VL 

- liquid velocity, rn/s 

Vg 

- vapor velocity, rn/s 

Hw 1 

- coefficient of heat transfer from the rod to the coolant, W/ 

m2 K 

KHWI 

- fouling factor 

t 

- time, s 

exp 

- experimental value 

cal 

- calculated value 

vol 

- volume 

sv 

- subvolume 

sj 

- single junction 

n 

- node 

hs 

- heat structure 

RRC KI 

- Russian Research Center "Kurchatov Institute" 

VTI 

- Russian Thermal Technology Institute 

VVER 

- Russian light water reactor 

SB LOCA 

- small break loss of coolant accident 

LP 

- lower plenum 

UP 

- upper plenum 

HL 

- hot leg 

CL 

- cold leg 

DC 

- downcomer 

SG 

- steam generator 

FA 

- fuel assembly 

FE 

- fuel element 

DAS 

- data acquisition system 

NC 

- natural circulation 

CCF 

- counter-current flow 

xii

I I
1. INTRODUCTION

1.1.Objectives 

The main goals of this work are: 

- Analysis and estimation of the VTI test data on the behavior of the rod's cladding temperatures in 

the partially uncovered VVER-440 core model using RELAP5/MOD3.2.2GAMMA; 

- Investigation thermal and hydraulic processes during steam-condensate natural circulation in the 

primary coolant system under SB LOCA conditions with small specific heat fluxes and medium 

pressures, and also in condition of absence of counter-current flow of phases in the uncovered part 

of the core; 

- Assessment of RELAP5/MOD3.2.2GAMMA code, especially its models for modeling heat 

transfer phenomena in the uncovered part of the core model. 

1.2. Background 

To help ensure RELAP5 code can be used with confidence, Russian Research Center "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 VTI tests with partially uncovered 

VVER-440 core model under SB LOCA conditions was performed using the latest version of code 

RELAP5/MOD3.2.2GAMMA. 

1.3. Study Description 

SB LOCA is one of the design basis accidents in VVER-440 power pressure water reactor. VVER

440 loop model is a semi-integral one loop model of VVER primary coolant system designed for 

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

In this facility series of the tests with partially uncovered VVER-440 core model under SB LOCA 

conditions were performed during 1984-1989 [1, 2]. 

Phenomena of hydrodynamics and heat transfer in VVER-440 core under uncovering conditions are 

specific. So, it is necessary to estimate RELAP5/MOD3.2.2GAMMA code models adequacy for 

modeling these phenomena, because there are specific features in design of the core and fuel

I
assembly of VVER-440. These specific features are the rod location in a triangular grid in the 

bundle, geometry of the rod and fuel assembly elements, hydraulic diameters of the rod bundle's 

cells and number of the spacer grids. Temperature of the fuel rod's cladding directly depends on 

these factors. 

VTI test 7.12.15.4 and test 8.6.3.2 with the partially uncovered core model were chosen to assess 

RELAP5/MOD3.2.2GAMMA. This code capability was investigated. Special emphases were given 

to: - thermal and hydraulic processes during steam-condensate natural circulation in the primary 

circuit with a mixture level in the partially uncovered core model and under conditions of small 

specific heat fluxes and medium pressures; - axial distributions of the coefficients of heat transfer 

from the heated rods to a steam flow and rod's cladding temperatures in the uncovered part of the 

core model under steady conditions with the transition mode of a steam flow in the core channel; 

the influence of an increase in the calculated coefficients of heat transfer from the heated rods to a 

steam flow on the axial distribution of rod's cladding temperatures in the uncovered part of the fuel 

assembly model. 

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

facilitate the code assessment. In Section 2 the VVER-440 Loop model at VTI Test Facility is 

described, and VTI tests 7.12.15.4 and 8.6.3.2 are 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 base case analysis results for the tests, discussion of the 

calculated and measured values and conclusions are presented in Section 5. Sensitivity studies are 

given in Section 6. Run statistics are given in Section 7. In Section 8 summary of conclusions is 

presented. In the Appendix D one finds the base case input deck listing for VTI test 8.6.3.2. 

2
2. DESCRIPTION OF VTI TEST FACILITY

2.1. Description of the VVER-440 loop model at VTI Test Facility 

The VVER-440 loop model at VTI Test Facility is a semi-integral one loop model of VVER 

primary coolant system. It has been designed for modeling of boiling-condensing mode in the 

primary coolant system and heat transfer processes in the partially uncovered core at small residual 

heat power and medium pressure under SB LOCA conditions of a reactor. A principle scheme of 

the VVER-440 loop model is shown in Fig.2. 1. 

This model includes the models of all the main elements of a reactor: - lower plenum model (1), 

core model with fuel assembly model (2), upper plenum model (7). Also, it includes the hot leg 

model (8), steam generator simulator (9) with an active heat removal and downcomer simulator. 

The SG simulator consists of the two parts: the upper part is a steam condenser, and the bottom part 

is a water cooler, which only qualitatively simulate hydrodynamics and heat transfer processes 

under conditions of steam condensation in the steam generator. 

The DC simulator at the bottom and the lower plenum model are connected by a lower water 

pipeline (11). The up-coming and down-coming circuit branches are linked in the upper part by a 

pipeline of the hot leg model. So, a natural circulation is formed in the model of VVER primary 

coolant system. An orifice installed in the lower water pipeline is used to measure a liquid mass 

flow rate at the core inlet during steam-condensate natural circulation in the loop. 

A secondary coolant system connected to the steam condenser provides a wide range of pressure 

Pup in the upper plenum. A secondary coolant system connected to the water cooler provides a 

wide range of water temperature TF at the core inlet. 

The mode parameters in the loop in the course of the series of the tests were varied in the following 

ranges: 

"* Pressure at the UP model outlet Pup: 23 - 73 bar; 

"* Specific heat flux in the FA model qw : 3.5 - 29 kW/m2; 

"* Mass flux in the FA channel : 1 - 7 kg/(m2 s). 

Water pipeline (10) from SG simulator into expansion tank is to drain a water through the valve. It 

serves for formation of the initial conditions with a break in two-phase natural circulation in the 

loop and with a mixture level in the partially uncovered core model. 

VTI Test Facility and DAS provide preparation and implementation of the planned experiments.

3
Fig.2.1 Scheme of the VVER-440 loop model and measurements on VTI Test Facility [2]: 

1 - Lower plenum; 2 - FA model; 3 - Insulator bush; 

4 - Pressure vessel; 5 - Protective electric heater; 6 - Upper conductor; 

7 - Upper plenum; 8 - Hot leg model; 9 - SG simulator and DC simulator; 

10 - Drainage pipeline; 11 - Lower water pipeline. 

4

4
2.2. Main components characteristics 

Core model with VVER-440 fuel assembly model. A sketch of the core model is presented in 

Fig.2.1. The core model consists of: - electrically heated VVER-440 fuel assembly model (2) 

enclosed by a pressure vessel (4) made of 12X1 8H1OT stainless steel tube with internal electric and 

heat insulator bushes of talkochlorite (3), protective electric heater (5) located on the outer surface 

of the pressure vessel, upper conductor (6) and lower conductor (12) for supply of current to the rod 

simulators. 

A power of the protective electric heater (5) located around the core pressure vessel (4) is to 

compensate heat losses from the outer surface of the core model to an ambient air. 

A cross section of the core model with the fuel assembly model is shown in Fig.2.2 b. 

Parameters of the core model with the fuel assembly model are presented in Table 2.1. 

Table 2.1. Parameters of the core model with VVER-440 fuel assembly model 

Heated length of the FA model 2500 mm 

Number of rod simulators 19 

Outer diameter of rod simulators 9.1 mm 

Distance between rod simulators 12.2 mm 

Size of FA channel hexahedron 56 mm 

Channel cross section area 0.001478 m2 

Heat transfer surface area of the FA model 1.358 m 2 

Hydraulic diameter of the FA channel 8.02 mm 

Designed axial and radial power distribution uniform 

Distance between spacer grids 240 mm 

Number of spacer grids 10 

Fuel assembly model. A sketch of the model of the VVER-440 fuel assembly is presented in 

Fig.2.2. The FA model consists of 19 electrically heated rod simulators of 9.1 mm outer diameter 

and of 2500 mm heated length. The rod simulators are composed in the rod bundle in a hexagonal 

array with a pitch equal 12.2 mm (P/D=l.34). The fuel assembly model is equipped with 10 spacer 

grids, axially located at equal distances of 240 mm. All the spacer grids are of VVER-440 FA type. 

The local hydraulic resistance coefficient of the grid is ý=0.27.

5
2500 (Heat release zone) 

240 x 9=2160

43 1

0

b)

Fig.2.2. Model of the VVER-440 fuel assembly. 

a) bundle of the rod simulators 

b) cross section of the core model with the FA model 

1. Steel cladding of the rod simulator 

2. Spacer grid 

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

4. Upper conductor 

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

6. Insulator bush 

7. Pressure vessel 

6

I I
Fuel rod simulators. The fuel rod simulators are electrically indirectly heated. The rod simulator 

consists of a stainless steel (12X18HlOT) heater made of a rod with outer diameter of 3.3 mm and 

length of 2500 mm, of a magnesium oxide (MgO) electrical isolation, and a stainless steel 

(12X18H1OT) cladding with wall thickness of 0.5 mm. 

The present fuel rod simulators are designed to have the uniform axial and radial heat flux 

distributions. The fuel assembly model is heated by the alternating current passing through these 

stainless steel heaters. Therefore, the power distribution within the rod bundle is uniform only in the 

conditions of full FA covering with a boiling liquid. 

51 cable thermocouples of 0.3 mm outer diameter are embedded in grooves inside the rod 

simulator's cladding at 32 elevations in the FA model. 

Upper plenum model. The location of the Upper plenum model (7) in the VVER-440 loop model 

is shown in Fig.2.1. It is made of a stainless steel tube 0 108 x 8 (Dh==92 mm) with the height of 

2.6 m. A power of the protective electric heater located around the upper plenum is to compensate 

heat losses from the outer surface of the upper plenum model to an ambient air. 

Hot leg model. Hot leg model (8) shown in Fig.2.1 is a pipeline made of a stainless steel tube 0 60 

x 8 (Dh=44 mm) with length of 3.0 m. 

Lower water pipeline. The lower water pipeline (11) is made of a stainless steel tube 0 16 x 3 

(Dh=10 mm) with length of 3.0 m. 

2.3. Measurements and errors 

Locations of the gauges in the Lower plenum model, Core model, Upper plenum model and Lower 

water pipeline are presented on a scheme of measurements in VVER-440 loop model, shown in 

Fig.2.1. 

Measurements of core axial and radial distributions of the rod's cladding temperatures were made 

with 51 thermocouples installed in cladding of the rod simulators (in 6 rods) at 32 elevations in the 

FA model. A scheme of location of the thermocouples along the FA height is shown in Fig.2.3. The 

thermocouples are numbered as 0 - 50 on Fig.2.3.

7
cyF B A E D

2) 

2324 mm

15,16> 

2084 mm

24,25) 

1844 mm

1605 mm

4-4

(o0,1

6 

13

. 19 

S27

< 41

,.7 

,. 17

K

( 

K

23 

29 

30 

31 "11

33 

38 

39

,118' 

,. 14 

18

20 

28-

(3534

< 43 

1365 mm 44 

405 mm K 

-1K 

165 mm__

< 3,4 

<5 

K 9,10 

< 12 

-< 21,22 

< 26

K 36,37 

< 40 

< 42

45 

46 

47

48 

49 

50

K

Fig.2.3. Scheme of location of the thermocouples along the FA model height [2]. 

8

I I

C/F B A E D
Measurements of the rod's cladding temperatures along the height of the FA model at 32 elevations 

have provided also an axial distribution of the rod's cladding temperatures in the FA model and test 

data about a mixture level in the FA channel with accuracy of ± 25 mm. 

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

U on the FA model and current. 

List of the measured parameters, and their measurement errors are presented in Table 2.3. 

Table 2.2. List of measured parameters used in calculations and measurement errors 

Parameter Measurement error 

Electric power W of the FA model ±2 % 

Water mass flow rate G in the lower pipeline ± 3 % 

Pressure Pup at the UP outlet ±0.4 % 

Coolant temperature TF ± 1.8 % 

Rod simulator's cladding temperatures TW ± 1.4 %

3. DESCRIPTION OF THE TESTS 

3.1. VVER specific phenomena investigated in the tests 

Phenomena of hydrodynamics and heat transfer in VVER-440 core under uncovering conditions are 

specific. So, it is necessary to estimate RELAP5/MOD3.2.2GAMMA code models adequacy for 

modeling of these phenomena, because there are specific features in design of the core and fuel 

assembly of a reactor. These specific features are the rod location in a hexagonal array, geometry of 

the rod and FA elements, hydraulic diameters of the rod bundle's cells, and enlarged number of the 

spacer grids. Temperature of the fuel rod's cladding directly depends on these factors. 

Comparison of the key parameter values for the FA model and corresponding values in VVER-V0 

reactor is presented in Table 3.1. 

Processes of hydrodynamics and heat transfer in the partially uncovered core under SB LOCA 

conditions are very important for VVER-440 safety, since at these conditions there is rod 

temperature increase realization, which may lead to rod damage. For safety analysis it is very 

important to know the initial time moment and conditions of FA uncovering, behavior dynamics of

9
a mixture level, distributions of the velocities of a vapor and liquid in the FA channel, and also the 

distributions of the heat transfer coefficients, rod's cladding temperatures and vapor temperatures 

above the mixture level. 

Table 3.1.Parameters of the core model with VVER-440 fuel assembly model and VVER-440 fuel 

assembly

Key parameter values VTI experiment

Configuration of the rod assembly 

Heated length of the rod assembly 

Number of rods in the rod assembly 

Outer diameter of rod

Distance between rods (rod pitch) 

Distance between spacer grids 

Shroud material 

Cladding material

Hexagonal 

2500 mm 

19 

9.1 mm

12.2 mm 

240 mm 

Talkochlorite 

12X18H1OT

3.2. Experiment performance technique 

To investigate a heat transfer in the partially uncovered core model, VTI test 7.12.15.4 and test 

8.6.3.2 were carried out in conditions of a break in two-phase natural circulation in the VVER-440 

loop model, and with a coolant collapsed level in the middle of the core model height. These two 

tests were conducted with small specific heat fluxes qwl and medium pressures, and also under 

conditions of absence of counter-current flow of a steam and its condensate in the core uncovered 

part. 

In these tests the behaviors of the rod's cladding temperatures have been studied in the steady 

regimes with the following values of the main parameters: 

- Power of the fuel assembly model W=16.8; 23.0 kW; 

- Pressure in the UP model Pup=27.3; 70.1 bar; 

- Mixture level in the FA channel Lm=1.87 m; 

- Temperature of rod simulator's cladding TW < 950 K.

10

VVER-440 

Hexagonal 

2500 mm 

126 

9.1 mm

I -

12.2 mm 

240 mm 

Zr-2.5%Nb 

Zr-1%Nb

I
The tests essentially differ by the conditions of their performance. These conditions cover wide 

range of VVER accidental conditions. In particular, the different heat fluxes, pressures, mass flow 

rates of a generated steam in the FA model were realized during these tests (see Table 3.1). At the 

same time the mixture level Lm (texp) in the FA channel was at the same position in both tests. 

The steady regime was conducted as follows. The up-coming and down-coming branches of the 

loop got warm with a steam, and then were filled with a steam condensate which expelled an air 

from the loop. The loop was cut off from a source of a steam condensate, and the power-up attained 

value of FA power specified in the test. 

To provide test conditions, it was performed preliminary heating of a water and pipeline metal up to 

required coolant temperature at the core model inlet under natural circulation. Coolant pressure was 

increased, and then coolant drainage from the lower pipeline to an expansion tank via the valve was 

started. Boiling NC regime was started under slightly greater pressure Pup than needed. 

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. Coolant collapsed level in the Upper plenum model 

was controlled with differential manometer DP2. Then collapsed level was fallen down to the set 

value of the initial collapsed level in the FA channel. Thus there was set a partial uncovering in the 

core model using water drainage from the lower pipeline to an expansion tank through the valve. 

Coolant collapsed level was controlled with differential manometer DP3 in the SG simulator and 

with differential manometer DP1 in the core model. 

Changing the flow rate and temperature of a secondary coolant fed to a steam condenser and to a 

water cooler, the regime of a break in two-phase natural circulation was established in the loop 

under required stationary conditions. Due to a balance between steam generation and steam 

condensation in the loop, a "steady regime" was realized at the stable values of pressure Pup (texp) 

in the upper plenum and of mixture level Lm (texp) in the FA channel, and at the stable rod's 

cladding temperatures TW (texp). This steady regime was realized at constant mass flow rate G and 

temperature TF of a subcooled water at the FA inlet, and at a constant electric power W (texp) of 

the FA model specified in the test. 

To avoid steam condensation in the up-coming branch of the loop model, and, as a consequence, to 

avoid counter-current flow of a steam and its condensate in the uncovered part of the core model, 

the protective electric heaters located around the core pressure vessel and upper plenum were used. 

To compensate heat losses from the outer surface of the core model to an ambient air, the power of 

each section of the protective electric heater located around the core pressure vessel was controlled

11
depending on a temperature differential of the coolant and the pressure vessel wall at the 

corresponding elevation in the core model. The power of each section of the protective electric 

heater located around the upper plenum was too controlled to compensate heat losses to an ambient 

air. 

After establishment of the required initial conditions in the VVER-440 loop model (see Table 3.1) 

the test for investigation of a heat transfer in the partially uncovered core model was started. The 

steady regime was conducted during - 1 hour. 

3.3. Initial and boundary conditions 

3.2.1. Boundary conditions at the outer surfaces of the VVER-440 loop model. Heat losses 

As noted above, to avoid a steam condensation in the up-coming branch of the loop model, and, as a 

consequence, to avoid counter-current flow of a steam and its condensate in the uncovered part of 

the core model, the protective electric heaters located around the core pressure vessel and upper 

plenum were used. 

In this case heat losses and their distribution along the up-coming branch of the loop model may 

weakly influence on the rate of steam cooling and its condensation, hence, on the mass flow rate of 

a condensate, flowing into the SG model and into the inlet of the core model. Therefore, a real 

distribution of heat losses on the length of the hot leg model and down-coming branch of the loop 

model can not essentially influence on the code results for the behavior of rod's cladding 

temperature in the uncovered FA part. 

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

A temperature regime of the heated rod in the uncovered part of the FA model is directly coupled 

with two-phase mixture level dynamics in the core under steam-condensate natural circulation in 

the primary coolant system. In this case a mixture level determines also a vapor mass flow rate in 

the uncovered part of the FA model. Therefore, adequate test data about the mixture level in the FA 

channel are required to calculate the rod's cladding temperatures. 

The FA model consists of 19 fuel rod simulators with just the same design, in which the identical 

heater's elements are made of stainless steel rods with the same outer diameter of 3.3 mm. 

Therefore, during water boiling in the full wetted FA model and under nearly uniform distribution 

12

I I
of the rod simulator's cladding temperatures, the specific volumetric power qv and heat flux qw 

distributions in the parallel rod heaters are too uniform on radius and height of the FA model. 

But, under condition of the partially uncovering of the FA model, axial and radial distributions of 

the rod simulators temperatures become essentially non-uniform. Under electric heating of the rod 

simulator's heaters, the local power at the various elevations in the FA model is determined by the 

electric resistance of the heater element, which essentially increases with temperature increase of 

the cladding and with temperature raising of the heaters in the fuel rod simulators. The influence of 

the electric resistance variation of the heater element with temperature on the radial and axial power 

distributions in the FA model may be taken into account using the distribution of measured rod's 

cladding temperatures and reference data [3] about specific electric resistance of l2X18HlOT 

stainless steel at various temperatures. 

During the test coolant temperature along the loop varied in a certain range, so variations of heat 

conductivity and specific heat capacity of the talkochlorite insulator, and stainless steel tubes and 

rods in the core model were noticeable. Therefore, the temperature dependencies of these 

parameters were used for the code calculations. 

The initial and boundary conditions for modeling the steady regime are as follows: 

- DC model and Lower plenum model have been filled up with a liquid under defined temperature 

TF (tOexp) and with a mixture level Lm (tOexp) in the Core model, and corresponding collapsed 

level in the DC model; 

- the other parts of the loop model located above the mixture level: Upper plenum model, Hot leg 

model, SG simulator have been filled up with a superheated steam at the specified pressure Pup 

(tOexp); 

- the water mass flow rate at the core inlet is determined by a driving head under condition of 

steam-condensate natural circulation in the loop model at the specified FA model power W (t0exp); 

- FA axial and radial distributions of rod's cladding temperatures TW (x) are determined in a steady 

regime at the specified conditions with constant in time FA model power W (tOexp) in the test. 

The time interval for cladding temperature stabilization in the fuel rod simulators was smaller than 

1 hour. When the protective electric heaters were used, this time interval was enough for a complete 

temperature stabilization of the talkchlorite insulator and core pressure vessel having essentially 

greater thermal inertia than ones of the fuel rod simulators.

13
Non-steady heating of the talkchlorite insulator, of the core model pressure vessel may be 

calculated, if specific densities, heat capacities and thermal conductivity coefficients of the stainless 

steel and talkchlorite are known [3, 4]. 

3.4. Experimental Data used 

This report presents test data on the behaviors of the rod's cladding temperatures TW (texp) along 

the FA model height and pressure Pup (texp) at the upper plenum outlet at constant in time FA 

power W (texp). 

The initial values of the determinative parameters for test 7.12.15.4 and test 8.6.3.2 in steady 

regimes are presented in Table 3.1. Original data plots from test 7.12.15.4 and test 8.6.3.2 are 

presented in Figures A-1 and A-2, accordingly, in the Appendix A. Complete set of experimental 

data obtained in the VVER-440 loop model at VTI Test Facility is in [1, 2]. 

Table 3.2. Initial values of determinative parameters for test 7.12.15.4 and test 8.6.3.2 in steady 

regimes 

Test code FA power FA average Pressure at Mixture NC mass Mass flux 

heat flux the UP outlet level flow rate, in the FA 

W (t0exp), qw Pup (t0exp), Lm(tOexp) G(tOexp), channel 

kW kW/m2 bar m kg/s kg/mi2 s 

7.12.15.4 16.8 12.4 27.3 1.87 5.1 -3 3.46 

8.6.3.2 23.0 17.0 70.1 1.87 6.5 -3 4.40 

Experimental axial distributions of the rod's cladding temperature in steady regimes for test 

7.12.15.4 and test 8.6.3.2 were used for comparisons with the code results. 

An experimental axial distribution of the rod's cladding temperature for test 7.12.15.4 is presented 

in Fig.A-1, and an axial distribution of the rod's cladding temperature for test 8.6.3.2 is presented in 

Fig.A-2. As seen, there are three characteristic areas in the axial distribution of the rod's cladding 

temperature: 

- Area 1 where the rod's cladding temperature increases on the length of an economizer section of 

the FA model; 

- Area 2 where the rod's cladding temperature is fixed and close to saturation temperature at the 

specified pressure in the FA channel; 

14

I
- Area 3 where the rod's cladding temperature sharply increases on the height of the FA 

uncovered part. 

The position of a boundary line between 1 and 2 areas is determined by the beginning of boiling on 

the surfaces of the rod simulators. The position of a boundary line between 2 and 3 areas is 

determined by dry out of a liquid film on the surfaces of the rod simulators. In this case the 

following assumption is used. A real mixture level is that level in the FA channel, at which a sharp 

increase of void fraction and local dryout of the rod's surface take place. And then a sharp decrease 

of the coefficient Hwl (x) of heat transfer from outer surfaces of the rods to a coolant, and a local 

increase of the rod's cladding temperature TW (x) above saturation temperature take place, also. 

The mixture level in the FA channel is determined in basic by the coolant mass inventory in the 

loop, specific heat flux qwl (x) on the outer surfaces of the rods, mass flow rate G and temperature 

TF of a liquid at the core inlet, and also pressure in the core model. 

An experimental axial power distribution of the rod simulator's heater was calculated taking into 

account the influence of an electric resistance variation of 12X18HIOT stainless steel with 

temperature on the power distribution in the partially uncovered FA model in a "steady regime". An 

experimental axial power distribution of the rod simulator's heater for test 7.12.15.4 is presented in 

Fig.3.1, and an axial power distribution of the rod simulator's heater for test 8.6.3.2 is presented in 

Fig.3.2. 

For modeling the experimental initial and boundary conditions also it is necessary to know the real 

position of a mixture level in the FA channel. Therefore, the mixture level Lm (tOexp) in the FA 

channel is presented in Table 3.2, too. The mixture level Lm (tOexp) in the FA channel and its 

behavior Lm (texp) have been found out by a special analysis of the test data about rod's cladding 

temperatures TW (texp) and an axial distribution of the cladding temperatures TW (x) (see Fig. A-1 

and Fig.A-2). 

As seen, the same mixture levels in the FA channel, equal - 1.87 m were realized in these tests; but 

different values of the vapor mass flow rate Gg and vapor velocity Vg were realized in the 

uncovered part of the FA owing to the given different values of FA power, mass flow rate G and 

water temperature TF at the core inlet; and also pressure in the core model. The maximum 

temperature of the rod cladding was near 940 K which was measured in the uppermost part of the 

FA model.

15
1.1 

CT 

0) 

09 10 

0.9 

0.8

Test? 2.2.54 / 

I 1 1

0 500 1000 1500 

Length (mm)

2000 2500

Fig.3.1. Experimental axial power distribution of the rod simulator's heater for test 7.12.15.4.

1.2

1.0 

(C 

1.0 

CT 

CT 

0.9 

0.8

C -

U 0UU 1000 1500 

Length (mm)

2000 2500

Fig.3.2. Experimental axial power distribution of the rod simulator's heater for test 8.6.3.2. 

16

I I

T + P ' -"
Analyzing the axial profiles of the rod's cladding temperatures it is possible to identify their almost 

linear character on the height of the FA uncovered part (see Fig.A- 1, A-2). At the same time, it is 

visible, that near above a mixture level the temperature gradient on the FA height is a little bit 

higher than far from it. 

Comparing the rod's cladding temperatures measured at the same levels, but on different rods in the 

bundle it was found out [1, 2], that the central rod and the rods located in the middle row in the 

bundle are in, practically, equal temperature conditions. Therefore, test data about cladding 

temperatures of the central rod and of the rods in the middle row marked as A, B, C, E and F in a 

cross section of the bundle (see Fig.2.3) were used for the comparisons with the code results. 

4. DESCRIPTION OF RELAP5 MODEL AND BASE CASE INPUT DECK FOR THE 

TESTS 

4.1. Code description 

The code used for this work was RELAP5/MOD3.2.2GAMMA [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 computer with processor Pentium 2 - 450 MHz. Windows 95 was used as an 

operating system. 

4.2. RELAP5 model and Input Deck development 

Figure 4.1 shows the nodalization to simulate the VVER-440 loop model and the test with 

RELAP5/MOD3.2.2. The code modeling of the test followed the specific calculation procedure 

used for simulation of the experimental initial and boundary conditions. 

The RELAP5 model consists of all the components of the primary and secondary circuits of the 

VVER-440 loop model, in total of 12 RELAP5 components with 131 hydrodynamic Volumes, 129 

Junctions and 167 Heat Structures with 611 mesh points. A complete listing of the base case input 

set for test 8.6.3.2 is listed in the Appendix E. 

Nodalization scheme for VVER440 loop model includes the following components of the primary 

circuit: - Lower Plenum model (v. 5, sj. 6), Core model (v. 7, sj. 8), Upper Plenum model (v. 9, sj. 

10), Hot Leg model (v. 11, sj. 12), SG simulator with a steam condenser (sv. 1401 - sv.1406) and 

Cold Leg simulator with a water cooler (v. 1415 - 1420), and Lower Water Pipe (sv. 1601 - 1616, 

sj.17).

17
A "pipe" hydrodynamic component Core Model 7 (sv. 701 - sv. 742), representing the test FA 

channel's fluid volumes, is connected to Lower Plenum model 5 at the bottom and to Upper Plenum 

model 9 at the top by the Single Junctions (SJ 6, SJ 8). 

Volumes from 701 to 740 represent the part of the core channel with the heated rod bundle. Here 

the core node pitch equal a quarter spacer grid pitch (1/4 Psg = 60 mm) was chosen. 

A "pipe" hydrodynamic components Upper Plenum 9 (sv. 901- sv. 915), representing the test UP 

fluid volumes, is connected to Core Model at the bottom and to Hot Leg at the top by the Single 

Junctions (SJ 8, SJ 10). 

A "pipe" hydrodynamic component Hot Leg (sv. 1101 - sv. 1118), representing the test HL fluid 

volumes, is connected to SG simulator by Single Junction (SJ 12). 

A "pipe" hydrodynamic component Lower Water Pipe 16 (sv. 1601 - sv. 1616) represents the test 

Lower Water Pipeline's fluid volumes with initial water temperature TF (tOexp). 

Heat structure scheme used to describe power distribution of the heated rod bundle and circuit heat 

losses in an environment is shown in Figure 4.1.Taking into account our experience of the code 

simulation of the Standard Problem INSCSP-V4 [7], when modeling the core model with the FA 

model a fine nodalization was chosen for hydrodynamic components and heat structures along the 

FA height. This nodalization was connected to the pitch between spacer grids. When calculating 

hydrodynamics and heat exchange in the FA channel, such a nodalization scheme makes it possible 

to account the influence of all the spacer grids located with the pitch of 240 mm in the FA heated 

region. 

A fine nodalization with 40 nodes for hydrodynamic components and heat structures along the FA 

height is used to have accurate calculations for the initial mixture level location Lm (tO cal) and its 

behavior during transient, and also for the experimental axial power distribution of the rod 

simulator's heater and axial distribution of rod's wall temperatures for the test. 

The rod simulator's heaters were modeled with "heat structure" components with internal heat 

sources to be uniformly distributed on the heater radius and non-uniformly distributed on the heater 

height (see Fig.3.1 and Fig.3.2). 

Boundary conditions on the rod simulator's outer surfaces were set with Right Boundary Condition 

Cards with boundary condition type W3 (I)=110 ("Vertical bundle without crossflow" with P/D 

=1.34). Heat transfer hydraulic diameter (i.e., heated equivalent diameter) De=10.9 mm is used for 

the core channel with the heated FA model. 

18
Hot Leg Qloss

Upper 

Plenum

01 

Lower 02 16 

Plenu • 1

Lower Water Pipe

Fig.4. 1. Base case nodalization scheme of VVER-440 loop model at VTI Test Facility.

19
To account the heat exchange processes to be impact by the grids, "Additional Right Boundary 

Cards" were used. Local hydraulic resistance ý=0.27 is to simulate 10 spacer grids arranged with 

the pitch of 240 mm in the heated region. 

Channel walls of the Core model, UP, HL, SG and Lower Water Pipeline were also modeled with 

"heat structure" components in order to simulate heat accumulation in the metal and external heat 

losses, if ones needed. 

4.3. Method of computer modeling of the experiments 

This computer model makes it possible to simulate directly the experiment. When computer 

modeling the experiment the problem is setting up the adequate thermal and hydraulic 

characteristics of the components in the primary and secondary circuits. 

Mixture level determines the power portion for a steam generation in the covered part of the FA 

model and, accordingly, mass flow rate Gg (texp) of a saturated steam at the inlet of the FA 

uncovered part. Also, the mixture level determines the power portion in the FA uncovered part. The 

power portion in the FA uncovered part determines heat-up and distributions of the steam flow's 

temperatures and rod simulator's temperatures along the height of the FA uncovered part. 

Thus, to calculate the distribution of rod's wall temperatures along the core height it is necessary to 

have accurate data about the initial mixture level Lm (t0exp) and its behavior Lm (texp) during the 

test. 

In the uncovered part of the FA model it is possible local power excess over a heat transfer from the 

rod surface to a steam flow. As a result, local rod's 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 the rod simulator part is possible. Hereof, the rate of 

change of rod's wall temperature during local heating or local cooling with the certain local power 

and known heat capacity is one of the main determined parameters of a heat transfer in the 

uncovered part of the FA model. This rate dTW/dt and absolute value of rod's wall temperature TW 

characterize a heat transfer in the uncovered part of the core model. 

Local value of the rod's wall temperature is determined by local temperature of a steam flow and by 

the local temperature difference between a steam and rod's wall. This difference is determined by a 

local heat flux qw and by a heat transfer coefficient Hwl.

20
Temperature distribution in a steam flow along the core height depends on the steam mass flow rate 

and also on intensity of a heat exchange between the steam flow and the surfaces of the rods and 

talkochlorite insulator. Also, it depends on intensity of an interphase heat exchange of a superheated 

steam and condensate under counter-current flow, which may be formed in the Upper Plenum and 

Core model when the protective electric heaters are not used. 

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

regime of the inner wall of insulator TWi (t) are determined by intensity of the heat transfer: 

- between coolant and talkochlorite insulator; 

- between outer surface of the core model pressure vessel and an ambient air when the protective 

electric heaters are not used. 

Heat flux qw2 (t) and its stabilization time also depend on the thermal conductivity coefficients and 

relatively large heat capacities of the considered massive parts of the core model. 

Thus, quality of the code modeling for rod temperature behavior in the uncovered part of the FA 

model depends on both accurate simulation of hydrodynamic processes in the loop model and 

accurate simulation of processes of a heat transfer from the rod simulators to the coolant flow and, 

further, in an environment. 

Therefore, to simulate a heat transfer in the partially uncovered FA model in a "steady regime", it is 

necessary to provide close coincidence of the calculated and experimental values of pressure Pup 

(tcal) and Pup (texp), mixture level location Lm (tcal) and Lm (texp) in the FA channel, coolant 

temperature at the core inlet TF (tcal) and TF (texp), and of a steam generation rate in the FA 

channel Gg and liquid mass flow rate G at the core inlet. 

Also, it is important to take into account the influence of an interphase heat transfer on complex 

processes in the uncovered part of the core model, if CCF takes place in the up-coming branch of 

the loop during the test when the protective electric heaters have not been used [7, 8]. 

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

experiment) have to be adequate provided during the code simulation using specified boundary 

conditions: 

- behavior of heat release power in the FA model W (texp); 

- initial value of pressure at the upper plenum model outlet Pup (tOexp); 

- initial value of coolant temperature at the FA model inlet;

21
- initial distribution of void fraction on the length of the NC circuit and also on the height of the FA 

channel; 

- initial distributions of temperatures of vapor and liquid on the length of the NC circuit; 

- initial distributions of averaged on wall thickness wall's temperatures of pipelines, core pressure 

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

- initial distributions of temperatures of the rod simulators and inside parts of the core model with 

talkochlorite bushes; 

- pressure and temperature of a secondary coolant at the inlet of a steam condenser; 

- mass flow rate of a secondary coolant at the inlet of a steam condenser; 

- pressure and temperature of a secondary coolant at the inlet of a water cooler; 

- mass flow rate of a secondary coolant at the inlet of a water cooler; 

- power of heat losses from the outer surfaces of the loop to an ambient air. In our case the heat 

losses are compensated by particular power of the protective electric heaters. 

All the mentioned above parameters govern further behaviors of the following determined 

parameters: 

- pressure at the upper plenum model outlet Pup (tcal); 

- coolant temperature at the FA model inlet TF (tcal); 

- mixture level in the FA channel Lm (tcal); 

- mass flow rate of a coolant at the core model inlet G (tcal) under NC conditions; 

- mass flow rate of a steam condensate GL out (tcal), flowing down from circuit elements to the core 

model outlet (in our case it is absent when the protective electric heaters are used); 

- flow rate of a steam condensate G (tcal), flowing down from circuit elements to the SG simulator 

and then to the core model inlet; 

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

- distribution of steam velocity Vg (teal) on the height of the uncovered part of the FA model; 

- distribution of steam temperature Tg (tcal) on the height of the uncovered part of the FA model; 

- distribution of temperatures of the outer surfaces of the rod simulators TW (tcal) on the FA height; 

rates dTW/dt; 

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

the coolant on the FA height; 

- distribution of coefficient Hw2 (tcal) of heat transfer from a coolant flow to the talkochlorite 

insulator on the core height;

22
- distribution of specific heat flux qw 1 (tcal) from the outer surfaces of the rod simulators to the 

coolant on the FA height; 

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

the FA height; 

- distribution of specific heat flux qwloss (teal) from the outer surface of the core pressure vessel to 

an ambient air (heat losses are absent when the protective electric heaters are used). 

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

RELAP5/MOD3.2.2GAMMA adequacy to simulate separate phenomena/processes of heat transfer 

in the uncovered part of the core model. Simulations of hydrodynamic phenomena in the main loop 

components, presumably, have been considered as auxiliary tasks. Solution of these tasks was 

necessary to provide the required initial and boundary conditions in the partially uncovered core 

model. 

Such approach is stipulated by the fact, that when modeling the interdependent hydrodynamic and 

thermal processes in the loop, essential shortcomings are possible during code simulation of such 

hydrodynamic parameters as the mixture level, void fraction distribution, distributions of mass flow 

rates and velocities of the phases, and interphase heat exchange along the height of the uncovered 

part of the FA model. In our opinion a special analysis of the code adequacy for simulation of 

mentioned hydrodynamic parameters in the loop need to be additionally implemented in a separate 

Standard Problem. 

Therefore, to diminish possible effects of these shortcomings on the calculation results for axial 

distributions of the heat transfer coefficients Hwl (tcal) and rod's wall temperatures TW (tcal), a 

special method has been developed for computer modeling the initial and boundary conditions in 

the partially uncovered core model for each separate test. 

When modeling an experiment using RELAP5/MOD3.2.2GAMMA the definition of a certain 

steady state with known boundary conditions at the initial moment of time tOcal is required. Starting 

with this point and using a certain transition procedure, it is possible to achieve such a steady state, 

that one most adequate describes a steady state in the loop and core model at the initial time 

moment tOexp in the experiment. 

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

hydrodynamic processes in the loop components and in the loop as a whole can lead to essential 

inaccuracies of the calculated parameters. So, in our method of computer modeling of the test there

23
is an opportunity to adjust a mixture level in the FA channel by selection of the suitable liquid mass 

inventory ML in the loop and initial pressure Pup (tOcal). 

The mixture level Lm (tcal) = Lm (tOexp) in the FA channel and its behavior Lm (tcal) are 

determined by a special analysis of the calculation results and test data about the behaviors of rod's 

wall temperatures TW (t) and their axial distribution, and also temperature change rates dTW/dt. 

To avoid a steam condensation in the up-coming branch of the loop and, as a consequence, to avoid 

counter-current flow of a steam and its condensate in the uncovered part of the core model, the 

effect of the protective electric heaters, located around the core model and upper plenum, has been 

simulated using zero heat losses from the particular heat structures in an environment. 

After establishment of the required initial conditions in the loop (see Table 3.1) the code simulation 

of a heat transfer in the partially uncovered core model in a "steady regime" was started. 

Stabilization of the calculated determinative and determined regime parameters was achieved 

during the particular interval of time (up to -1 hour) which was used for a complete stabilization of 

the regime parameters under test conditions too. 

The results of comparisons of the calculated and measured values of the determinative and 

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

initial and boundary conditions, realizing in the test, and then about adequacy of the code 

simulation of a "steady regime". 

When calculating and assessing suitability of RELAP5/MOD3.2.2GAMMA and its modeling units 

for description of the separate phenomena and complex processes, it is conventional to use the 

options recommended by the code developers for actuating the code models under analogous 

conditions. The geineral modeling approaches recommended in the RELAP5 manuals [5, 6] should 

continue to be used. 

The following assumptions were made: 

0 Volume Vertical Stratification, Water Packing, Abrupt Area Change, Umbrella Model were 

process models activated for the corresponding circuit components; 

* Process models such as an additional model of counter-current flow limitation (CCFL Model), 

model of critical mass flow rate (Choked Model) and Reflood Model were not to be used in the 

corresponding loop components. 

24

I
When modeling transient in the core channel with the FA model, it was chosen a maximum time 

step dtmax =0.025 s. 

To describe interphase friction in the coolant in the FA channel, an option designating to a rod 

bundle (with flag b=l) is applied. Semi-implicit scheme of numerical integration specified with the 

tt=3 option is used to calculate conjugate hydrodynamics and heat transfer/conduction processes. To 

activate convective boundary conditions for non-standard geometry when modeling a vertical 

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

In the base case calculations for the tests, at use of the code models for description of a heat transfer 

in the FA model, it was pre-assigned Fouling factor Kvwl=1.0 to define the coefficients of heat 

transfer Hwl (tcal) in the uncovered FA part which are recommended by the code developers. 

To help development of an adequate nodalization scheme of the VVER-440 loop model and the 

computer methods of simulation of the initial and boundary conditions for each separate test, 

preliminary analyses of these tests were fulfilled using the code. 

5. RESULTS OF THE CODE ASSESSMENT 

5.1. Nodalization, including variations from base case 

Before choosing a final model, the effect of different nodalizations to the results of 

RELAP5/MOD3.2.2GAMMA calculations was investigated for VTI test 7.12.15.4. Of interest was 

the influence of number of hydraulic volumes and heat structures chosen. The different 

nodalizations were studied using 20 and 40 volumes for the core channel (hydrodynamic 

component 7) with the heated FA model by fixing the number of fine mesh nodes in the heat 

conduction elements. Here the core node pitch was chosen equal a half or a quarter spacer grid pitch 

(1/2 Psg =-120 mm or 1/4 Psg = 60 mm). 

As quality of the code modeling for rod's wall temperature behavior in the partially uncovered FA 

depends on accurate simulation of a mixture level in the core channel, it is necessary to provide 

close coincidence of Lm (tcal) calculated and Lm (texp) experimental values of the mixture level. 

Higher number of volumes results in more accurate code simulation of the mixture level in the core 

channel. And, also, higher number of the volumes results in smaller error (± 30 mm), when the real 

mixture level Lm (tlcal) = Lm (tOexp) and its behavior Lm (tcal) are determined by a special 

analysis of the calculation results for TW (tcal) and test data about rod's wall temperatures TW 

(texp). Measurements of the TW (texp) temperatures along the height of the FA model with 51

25
thermocouples on 32 elevations have provided the temperature axial distribution in the FA model 

and test data about a mixture level in the FA channel with accuracy of ± 25 mm. 

Therefore, when modeling the core model with the FA model, a fine nodalization was chosen for 

hydrodynamic components and heat structures along the FA height. A fine nodalization was 

connected to the pitch between spacer grids. When calculating hydrodynamics and heat exchange in 

the FA channel, this nodalization scheme makes it possible to account the influence of all the spacer 

grids located with the pitch of 240 mm in the FA heated region. 

Nodalization with 40 nodes for hydrodynamic components and heat structures along the FA height 

results in more accurate calculations for the initial mixture level Lm (tOcal) and its behavior during 

the transient, and also for the experimental axial power distribution of the rod simulator's heater 

and axial distribution of rod's wall temperature during the test. 

After the choice of proper nodalization and maximum user-specified time step dtmax, base case 

calculations were done for the tests. All the calculations to be presented latter in this report were 

performed by selecting the nodalization with 40 volumes for the core channel with the heated 

bundle as the base case (see Fig. 4.1). 

5.2. Base case results for test 7.12.15.4, comparisons to VTI test data and conclusions 

In this test the behaviors of the rod's cladding temperatures have been studied in a "steady regime" 

with the following values of the main parameters: 

- Power of the fuel assembly model W=16.8 kW; 

- Pressure in the UP model Pup=27.3 bar; 

- Mixture level in the FA channel Lm=l.87 m; 

During this "steady regime" a heat transfer in the core uncovered part takes place too under 

stationary conditions with the constant in time specific heat fluxes qw 1 (tcal), heat transfer 

coefficients Hwl (tcal) and rod's wall temperatures TW (tcal). 

The base case calculations were performed for VTI test 7.12.15.4 using maximum user-specified 

time step dt max = 0.025 s and fouling factor KHWI=l.0 to define the coefficients Hwl (tcal) of heat 

transfer from the rods to a steam flow in the uncovered FA part which are recommended by the 

code developers [5, 6]. 

26
During simulation of the test with RELAPS/MOD3.2.2GAMMA we have defined the initial and 

boundary conditions of a steady state at the time moment tOcal taking into account the results of 

our preliminary code calculations for the test. 

Starting from this steady state and using a procedure of the transition method, we have run the 

transition to such a steady state in the loop at the time tlcal which is adequate to the experimental 

"initial steady state" in the loop at the time moment tOexp. Code simulation of the transition was 

realized during the time interval from tOcal = 0 s to tlcal = 3000 s to set up the initial and boundary 

conditions and to achieve the needed "initial steady state" in the loop at the time tlcal=3000s. Then 

further code simulation for a "steady regime" was realized during the time interval from tlcal = 

3000 s to t2cal = 4000 s to illustrate a complete stabilization of the calculated values for the regime 

parameters during the particular time interval which corresponds to the test interval from the initial 

time tOexp=0 s to the end of the test at tlexp=1000 s. 

Within this time interval (Dtexp=1000 s) the calculation results for the "steady regime" and test 

data for VTI test 7.12.15.4 are presented as time-dependent curves on Figures B-1+B-13 in the 

Appendix B. The curves serve for comparisons of the base case calculation results with test data to 

demonstrate the code suitability. Also, the calculated histories of determinative and determined 

parameters are shown in the figures to examine hydrodynamic interactions between adjacent 

components in the loop. 

As in the test, during code modeling of the test the needed values of the mass flow rate G (tcal) and 

primary water temperature TF (tcal) at the inlet of the FA channel, and also pressure Pup (tcal) in 

the Upper Plenum were attained by change of the mass flow rate and temperature of a secondary 

coolant at the inlet of a Steam Condenser, and also by change of the mass flow rate and temperature 

of a secondary coolant at the inlet of a Water Cooler. 

Due to a balance between steam generation in the Core model and steam condensation in the loop 

as a whole, in the code calculations a "steady regime" was realized too at the stable values of 

pressure Pup (tcal) in the Upper Plenum and mixture level Lm (tcal) in the FA channel, and at 

stable rod's wall temperatures TW (tcal). This "steady regime" was realized also at constant values 

of the mass flow rate G (tcal) and temperature TF (tcal) of a subcooled water at the FA inlet, and at 

constant electric power W (tcal) of the FA model. 

The results of code simulation of the initial and boundary conditions for the test 7.12.15.4 are 

presented on Figures B- 1- B-6.

27
Comparisons of the calculation results and test data about the main regime parameters Pup(t) 

and G(t) at the FA inlet for the "initial steady state" are presented in Figures B-1 and B-3, 

respectively. In these figures one can see the calculated values of mentioned parameters are close to 

the experimental ones or they lie within the range of measurement accuracy. 

The assumption is accepted, that an evidence of a good accuracy of modeling the water temperature 

TF (tIcal) at the inlet of FA channel is a coincidence of the axial profile of calculated rod's wall 

temperature TW (tical) with the distribution of the measured rod's cladding temperatures on the 

height of the economizer section in the bottom part of the FA model (see Fig.5.1). 

1100 Test 7.12.15.4 ncooe=40 volumes; K, =l 1.0 RELAP5/MOD 2.2 

1000 00000 Tw exp 

BE=j- Tw cac 

"2 800- -P 

Q) 

o 7600 

5)600--

400 4O 1[ _ _ _ __ ~500___ ___ ___ ____ ___ __ ___ ___ ____ ___ ___ __ ,,, ,I* .*- * *. I,.* 

0 500 1000 1500 20000 2500 

Length (ram) 

Fig.5.l. Comparison of the axial profile of calculated rod's wall temperature TW (tlcal) and axial 

distribution of the measured rod's cladding temperatures TW (tOexp) for the initial time moment for 

test 7.12.15.4 at FA power W=16.8 kW and pressure Pup= 27.3 bar. 

A comparison of the axial distributions of experimental qw (tOexp) and calculated qwl (tlcal) 

specific heat fluxes from the outer surface of the rod simulator to a coolant for the initial time 

moment tlcal is shown in Fig. B-4. As seen, there is a good agreement between the calculated and 

experimental axial profiles of the specific heat flux in the FA model at the initial time. 

The mixture level Lm (tlcal) = Lm (tOexp) in the FA channel and its behavior Lm (tcal) are 

28
determined by a special analysis of the calculation results TW (tcal) and comparison of the axial 

profile of the calculated rod's wall temperature TW (tlcal) and axial distribution of the measured 

rod's cladding temperatures TW (tOexp) at the initial time moment (see Fig.5.1). The assumption is 

used, that a real mixture level is that level in the FA channel, at which a sharp increase of void 

fraction takes place in the upper part of the FA channel (see Fig.B- 11). And then the sharp decrease 

in calculated coefficient Hw 1 (x) of heat transfer from the outer surface of the rod to a coolant (see 

Fig. B-8) and, consequently, a local increase of the rod's cladding temperature TW (x) above 

saturation temperature take place, too. As seen in Fig.5.1, the calculated value Lm (tlcal) for a 

mixture level is nearly equal the initial mixture level Lm (tOexp) = 1.87 m in the test. 

Thus, the code results for the "initial steady state" are in good agreements with the test data about 

the main regime parameters: pressure Pup (t0exp), water temperature TF (tOexp), mass flow rate G 

(tOexp), mixture level Lm (t0exp) and heat flux qw (tOexp) in the core model. It provides the needed 

mass flow rate Gg (tlcal) of a generated steam flowing into the uncovered part of the core model 

under test conditions. 

Behavior of the calculated TW (tcal) rod's wall temperature in the upper, middle and bottom parts 

of the FA model during a "steady regime" are presented in Fig.B-5. There is a significant 

quantitative difference between the axial profile of the calculated rod's wall temperature TW (tlcal) 

and axial distribution of the measured temperatures TW (tOexp) in the uncovered part of the FA 

model (see Fig.5.1). RELAP5/MOD3.2.2GAMIMA over predicts rod's wall temperatures in the 

uncovered part of the heated FA model at the initial time moment. As seen, in the "initial steady 

state" the calculated TW (tlcal) rod's wall temperature is much higher (up to - 150 K) than 

measured one at the FA outlet. This is the main problem of the code for the base case calculations 

of the "initial steady state". 

It is a base for a conclusion about adequacy of the code simulation of the initial and boundary 

conditions only for hydrodynamics, realized in the experiment. At the same time, the code gives 

inadequate simulation of the heat transfer coefficients and axial distribution of rod's wall 

temperatures TW(tlcal) in the uncovered part of the FA model for the "initial steady state". 

The adequacy of the code for analysis of heat transfer phenomena in the uncovered part of the 

core model has been estimated by comparison of the axial profile of the calculated rod's wall 

temperature TW (t2cal) and axial distribution of the measured rod's cladding temperatures TW 

(tlexp) at the end of a "steady regime" at the time moment tlexp=1000 s (see Fig. B-6).

29
Comparisons of the measured and calculated histories of the parameters Pup (tcal) and G (tcal) 

illustrate a good coincidence of these curves during a "steady regime" in Figures B-1 and B-3, 

respectively, in the Appendix B. The accuracy is shown for the regime parameters coincidence in 

the calculation and experiment at analogous time moments (at the calculation time t2cal and 

experimental time tlexp). The coincidence of the behaviors of the calculated and measured 

parameters during a "steady regime" is shown too. 

As seen in Fig.B-6, in a "steady regime" the calculated TW (t2cal) rod's wall temperature is much 

higher (up to - 150 K) than measured one at the FA outlet. This is the main problem of the code for 

the base case calculations of the "steady regime" for test 7.12.15.4. 

To found out the physical reasons for these essential discrepancies between code predictions and 

test data, the histories of the calculated coefficients Hwl (tcal) of heat transfer in the uncovered part 

of the FA model are presented in Fig.B-7. An axial distribution of the calculated coefficients Hwl 

(t2cal) of heat transfer from the outer surfaces of the rods to a coolant in the upper part of the FA 

model is shown in Fig.5.2. Also, additional code results are shown too in Figures B-9÷B-13 in the 

Appendix B. 

The main reason for the deviations between the experiment and calculations may be too low 

coefficients Hwl (t2cal) = 58-78 W/m2.K of heat transfer from the outer surfaces of the rod 

simulators to a coolant which are calculated for the uncovered part of the FA model (see Fig.5.2). It 

is a base for a conclusion about adequacy of the code modeling only for hydrodynamics, realized 

during a "steady regime" in the test. At the same time, the code gives inadequate simulation of the 

axial distributions of the heat transfer coefficients Hwl(t2cal) and rod's wall temperatures in the 

uncovered part of the FA model at the end of a "steady regime". 

As seen in Figures B-9 and B-11, the calculated void fractions of a superheated vapor in the 

uncovered part of the core model are equal 1.0. It is the evidence of absence of counter-current flow 

in the uncovered part of the FA model. Therefore, these results give also the indications that the 

code models for modeling counter-current flow limitation (CCFL) and interphase heat transfer are 

not to be used for the uncovered part of the core model.

30
n-,=40 volumes; KHW,=I.0 RELAP5/MOD3.2.2 200-

175 

150

C12 5-

E 

i•r10 

F--S7 

5 

2

5- _ 

5 -.. . ._ . .. . _.. __.. 

1800 1900 2000 2100 2200 -2300 

Length (mm)

2400 2500

Fig.5.2. Axial distribution of the calculated coefficients Hwl (t2cal) of heat transfer from the rods 

to a coolant in the upper part of the FA model for experiment 7.12.15.4. 

Calculated Vg (tcal) vapor velocities histories in the upper part of the FA channel are shown in Fig. 

B-10. As seen, during a "steady regime" the vapor velocities Vg (tcal) at different elevations 

increase along the uncovered part of the FA model and the maximum value of vapor velocity is 

equal 0.52 m/s at the outlet of the FA model. The calculated axial distribution of the vapor 

velocities Vg (x) in the FA channel is shown in Fig.B-12. 

In this test the transition mode of a steam flow (this mode is realized between laminar and turbulent 

modes of a steam flow) is realized along the height of the uncovered part of the FA model with 

corresponding Reynolds numbers Reg= Vg -Dh /vg = 1650 - 830. An axial distribution of the 

calculated vapor temperatures Tg (x) in the uncovered part of the FA channel is shown in Fig.B-13. 

Sensitivity studies are needed to determine the main reason for these deviations between the test 

data and code results.

31

-F +-I- + I- -F F F

Test 7.12.115
Conclusions for VTI test 7.12.15.4

* RELAP5/MOD3.2.2GAMMA and the base case method of computer modeling of the VTI test 

7.12.15.4 have provided adequate simulations of the initial and boundary conditions only for 

hydrodynamics, realized in a steady regime with steam-condensate natural circulation in the VVER

440 loop model. In this test the transition mode of a steam flow is realized along the height of the 

uncovered part of the FA model with corresponding Reynolds numbers Reg= Vg -Dh /vg = 1650 

830. 

a The results for the "initial steady state" are in good agreements with the test data about the main 

regime parameters: pressure Pup (t0exp), water temperature TF (tOexp), mass flow rate G (t0exp), 

mixture level Lm (t0exp) and heat flux qw (t0exp) in the core model. It provides the needed mass 

flow rate Gg (t0exp) of a generated steam flowing into the uncovered part of the core model under 

the test conditions. 

* At the same time, RELAP5/MOD3.2.2GAMMA gives inadequate simulation of the heat transfer 

coefficients Hwl (tlcal) and axial distribution of the rod's wall temperatures in the uncovered part 

of the FA model for the "initial steady state". There is a significant quantitative difference of the 

axial profile of the calculated rod's wall temperature TW (tlcal) and axial distribution of the 

measured rod's cladding temperatures TW (tOexp) in the uncovered part of the FA model. The code 

over predicts rod's wall temperatures in the uncovered part of the FA model at the initial time 

moment and then during a "steady regime". The calculated TW (tlcal) rod's wall temperature is 

much higher (up to - 150 K) than measured one at the FA outlet. This is the main problem of the 

code for the base case calculations for the test 7.12.15.4. 

* The main reason for these deviations between experiment and calculations may be too low 

calculated coefficients Hwl (tlcal) - 58-78 W/m2

.K of heat transfer from the outer surfaces of the 

rod simulators to a coolant in the uncovered part of the FA model. It is a base for a conclusion about 

adequacy of the code simulation of the test conditions only for hydrodynamics, realized during the 

test. At the same time, the code gives inadequate simulation of the heat transfer coefficients Hw 1 

(tlcal) and behavior of rod's wall temperatures in the uncovered part of the FA model during the 

"steady regime". 

* Sensitivity studies are needed to determine the main reason for these deviations between the code 

results and test data.

32
5.3. Base case results for test 8.6.3.2, comparisons to VTI test data and conclusions 

In this test the behaviors of the rod's cladding temperatures have been studied in a "steady regime" 

with the following values of the main parameters: 

- Power of the fuel assembly model W=23 kW; 

- Pressure in the UP model Pup=70.1 bar; 

- Mixture level in the FA channel Lm=l.87 m; 

During this "steady regime" the regime of heat transfer in the core uncovered part is also stationary 

with the constant in time specific heat fluxes qwl (tcal), coefficients of heat transfer Hwl(tcal) and 

rod's wall temperatures TW (tcal). 

The base case calculations were performed for VTI test 8.6.3.2 using nodalization with 40 volumes 

for the Core model and maximum user-specified time step dt max = 0.025 s, and also using fouling 

factor KHwl=l.0 to define the coefficients Hwl (tcal) of heat transfer in the uncovered FA part 

which are recommended by the code developers [5, 6]. 

Taking into account the results of our preliminary code calculations for the test 8.6.3.2 we have 

defined the initial and boundary conditions of a steady state at the time moment tOcal. 

Code simulation of the transition procedure was realized during the time interval from tOcal = 0 s to 

tlcal = 3000 s to set up the initial and boundary conditions and to achieve the needed "initial steady 

state" in the loop at the time moment tlcal=3000s. Then further code simulation for a "steady 

regime" was realized during the time interval from tical = 3000 s to t2cal = 4000 s to illustrate a 

complete stabilization of the calculated regime parameters during the particular time interval which 

corresponds to the test interval from the initial moment tOexp=0 s to the end of the test at 

tlexp=1000 s. Within this time interval the calculation results for the "steady regime" and test data 

for VTI test 8.6.3.2 are presented as time-dependent curves on Figures C-1-C-13 in the Appendix 

C. 

The results of code simulation of the initial and boundary conditions for the test 8.6.3.2 are 

presented on Figures C-1÷C-6. Comparisons of the calculation results and test data about the main 

regime parameters Pup (t) and G (t) at the FA inlet for the "initial steady state" are presented in 

Figures C-1 and C-3, accordingly. In these figures one can see the calculated parameters are close to 

the experimental ones or they lie within the range of measurement accuracy.

33
The evidence of a good accuracy of modeling the water temperature TF (tlcal) at the inlet of FA 

channel is a coincidence of the axial profile of calculated rod's wall temperature TW (tlcal) with 

the distribution of measured rod's cladding temperatures on the height of the economizer section in 

the bottom part of the FA model (see Fig.5.3). 

100 Test 8.6.3.2 n,,,=40 volumes; KHWl= 1.0 RELAP5/MOD3.2.2 

1000 00000 1w exp DHIDEIEE] Tw catz 

0 0 

• 

-s 700 _ 

5 600 

500 ______ 

400 4 

0 500 000 500 2000 2500 

Length (mm) 

Fig.5.3. Comparison of the axial profile of calculated rod's wall temperature TW (tlcal) and axial 

distribution of measured rod's cladding temperatures TW (t0exp) for the initial time moment for 

test 8.6.3.2 at the FA power W=23 kW and pressure Pup= 70.1 bar. 

A comparison of the axial distributions of experimental qw (tOexp) and calculated qwl (tlcal) 

specific heat fluxes from the outer surface of the rod simulator to a coolant for the initial time 

moment tical is shown in Fig. C-4. As seen, there is a good agreement between the calculated and 

experimental axial profiles of the specific heat flux in the FA model at the initial time moment. 

The mixture level Lm (tical) = Lm (t0exp) in the FA channel is determined by a comparison of the 

axial profile of calculated rod's wall temperature TW (tlcal) and axial distribution of the measured 

rod's cladding temperatures TW (t0exp) at the initial time. As seen in Fig.5.3, the calculated value 

Lm (tlcal) for a mixture level is nearly equal the initial mixture level Lm (tOexp) = 1.87 m in the 

test.

34
Thus, the code results for the "initial steady state" are in good agreements with test data about the 

main regime parameters: pressure Pup (tOexp), water temperature TF (tOexp), mass flow rate G 

(tOexp), mixture level Lm (t0exp) and heat flux qw (tOexp) in the core model. It provides the needed 

mass flow rate Gg (tlcal) of a generated steam flowing into the uncovered part of the core model 

under test conditions. 

Behavior of the calculated TW (tcal) rod's wall temperature in the upper, middle and bottom parts 

of the FA model during a "steady regime" are presented in Fig.C-5. There is a significant 

quantitative difference between axial profile of the calculated rod's wall temperature TW (tlcal) 

and axial distribution of the measured temperatures TW (tOexp) in the uncovered part of the FA 

model (see Fig.5.3). The code over predicts rod's wall temperatures in the uncovered part of the 

heated FA model at the initial time moment. As seen, in the "initial steady state" the calculated TW 

(tlcal) rod's wall temperature is much higher (up to - 150 K) than measured one at the FA outlet. 

This is the main problem of the code for the base case calculations for the "initial steady state" for 

the test 8.6.3.2. 

It is a base for a conclusion about adequacy of the code simulation of the initial and boundary 

conditions only for hydrodynamics, realized in the experiment. At the same time, the code gives 

inadequate simulation of the heat transfer coefficients and axial distribution of the rod's wall 

temperatures in the uncovered part of the FA model for the "initial steady state". 

The adequacy of the code for analysis of heat transfer phenomena in the uncovered part of core 

model has been estimated by a comparison of the axial profile of the calculated rod's wall 

temperature TW (t2cal) in the FA model and axial distribution of the measured rod's cladding 

temperatures TW (tlexp) at the end of a "steady regime" at the time tlexp=1000 s (see Fig. C-6). 

Comparisons of the measured and calculated histories of the regime parameters Pup (tcal) and G 

(tcal) illustrate good coincidence of these curves during a "steady regime" in Figures C-1 and C-3, 

accordingly. 

As seen in Fig.C-6, at the end of a "steady regime" the calculated TW (t2cal) rod's wall temperature 

is much higher (up to - 150 K) than measured one at the FA outlet. This is the main problem of the 

code for the base case calculations for the "steady regime" for test 8.6.3.2. 

To found out the physical reasons for these essential discrepancies between code predictions and 

test data, the histories of the calculated coefficients of heat transfer Hwl (tcal) in the uncovered part 

of the FA model are presented in Fig.C-7. A core axial profile of the calculated coefficients

35
Hwl(t2cal) of heat transfer from the rods to a coolant is shown in Fig.C-8. Also, additional code 

results are shown too in the Figures C-8 -C-13 in the Appendix C. 

An axial distribution of the calculated coefficients Hwl (t2cal) of heat transfer from the outer 

surfaces of the rods to a coolant in the upper part of the FA model is shown in Fig.5.4.

500 

450 

400 

750 

S300 E 

S250 

z 200 

150 

'00 

50 

0 

it

Test 8.6.3.2 n,,,,=40 volumes; Kw= 1 .0 RELAP5/MOD3.2.2

_ _ I , _ _ _ _ 

rin 10 nn 1nnn noo o--~o)ZCO -ýo

Length (mrn)

Qjuo

Fig.5.4. Axial distribution of the calculated coefficients Hwl (t2cal) of heat transfer from the rods 

to a coolant in the upper part of the FA model for experiment 8.6.3.2. 

The main reason for the deviations between the experiment and code results may be too low 

coefficients Hwl (t2cal) = 180-98 W/m2.K of heat transfer from the outer surfaces of the rod 

simulators to a coolant which are calculated for the uncovered part of the FA model (see Fig.5.4). It 

is a base for a conclusion about adequacy of the code simulation of a "steady regime" only for 

hydrodynamics, realized in the test. At the same time, the code gives inadequate simulation of the 

axial distributions of the heat transfer coefficients Hwl(t2cal) and rod's wall temperatures in the 

uncovered part of the FA model for a "steady regime". 

As seen in the Figures C-9 and C- 11, the calculated void fractions of a superheated vapor in the 

uncovered part of the core model are equal 1.0. It is the evidence of absence of counter-current flow 

36

I I

•JU• Z•VU
in the uncovered part of the FA model. Therefore, these results give also the indications that the 

code models for modeling counter-current flow limitation (CCFL) and interphase heat transfer are 

not to be used for the uncovered part of the core model. 

Calculated Vg (tcal) vapor velocities histories in the upper part of the FA channel are shown in 

Figures C-10. As seen, during a "steady regime" the vapor velocities Vg (tcal) at different 

elevations increase along the uncovered part of the FA model and the maximum value of vapor 

velocity is equal 0.26 m/s at the outlet of the FA model. The calculated axial distribution of the 

vapor velocities Vg (x) in the FA channel is shown in Fig.C-12. In this test the transition mode of a 

steam flow is realized along the height of the uncovered part of the FA model with corresponding 

Reynolds numbers Reg= Vg -Dh /vg = 1860 - 1060. 

An axial distribution of the calculated vapor temperatures Tg (x) in the uncovered part of the FA 

channel for the test 8.6.3.2 is shown in Fig.C-13. 

Sensitivity studies are needed to determine the main reason for these deviations between test data 

and code results. 

Conclusions for VTI test 8.6.3.2 

* RELAP5/MOD3.2.2GAMMA and the base case method of computer modeling of the VTI test 

8.6.3.2 have provided adequate simulations of the initial and boundary conditions only for 

hydrodynamics, realized in a steady regime with steam-condensate natural circulation in the VVER

440 loop model. In this test the transition mode of a steam flow is realized along the height of the 

uncovered part of the FA model with corresponding Reynolds numbers Reg= Vg Dh /Vg = 1860 

1060. 

e The code results for the "initial steady state" are in good agreements with the test data about the 

main regime parameters: pressure Pup (tOexp), water temperature TF (tOexp), mass flow rate G 

(t0exp), mixture level Lm (t0exp) and heat flux qw (tOexp) in the core model. It provides the needed 

mass flow rate Gg (t0exp) of a generated steam flowing into the uncovered part of the core model 

under the test conditions. 

* At the same time, RELAP5/MOD3.2.2GAMMA gives inadequate simulation of the heat transfer 

coefficients Hwl (tlcal) and axial distribution of the rod's wall temperatures TW(tlcal) in the 

uncovered part of the FA model for the "initial steady state". There is a significant quantitative 

difference of the axial profile of the calculated rod's wall temperature TW (tIcal) and axial

37
distribution of the measured rod's cladding temperatures TW (t0exp) in the uncovered part of the 

FA model. The code over predicts rod's wall temperatures in the uncovered part of the FA model at 

the initial time moment and then during the "steady regime". The calculated TW (tlcal) rod's wall 

temperature is much higher (up to - 150 K) than measured one at the FA outlet. This is the main 

problem of the code for the base case calculations for the test 8.6.3.2. 

* The main reason for these deviations between experiment and calculations may be too low Hwl 

(tlcal) = 180-98 W/m -K coefficients of heat transfer from the outer surfaces of the rod simulators 

to a coolant in the uncovered part of the FA model. 

It is a base for a conclusion about adequacy of the code simulation of the test conditions only for 

hydrodynamics, realized during the test. At the same time, the code gives inadequate simulation of 

the heat transfer coefficients Hwl (tIcal) and behavior of rod's wall temperatures in the uncovered 

part of the FA model during the "steady regime". 

* Sensitivity studies are needed to determine the main reason for these deviations between the code 

results and test data. 

6. SENSITIVITY STUDIES 

This assessment work has shown, that RELAP5/MOD3.2.2GAMMA and methods of computer 

modeling VTI test 7.12.15.4 and test 8.6.3.2 have provided the adequate simulations of the initial 

and boundary conditions only for hydrodynamics, realized in these tests under steam-condensate 

natural circulation in the loop. 

There are significant quantitative differences of the axial profile of the calculated rod's wall 

temperature TW (tlcal) and axial distribution of the measured rod's cladding temperatures TW 

(tOexp) in the uncovered part of the FA model in the base case calculations for these tests. 

The code over predicts rod's wall temperatures in the uncovered part of the FA model at the initial 

time moment, and then during the "steady regime". The calculated TW (tlcal) rod's wall 

temperatures are much higher (up to - 150 K) than measured ones at the FA outlet. This is the main 

problem of the code for the base case calculations for these tests. 

The main reason for these deviations between experiments and calculations may be under 

estimation for Hw l(tcal) coefficients of heat transfer from the rod simulators to a steam in the 

uncovered part of the FA model in the stationary conditions with the transition mode of a steam 

flow in the channel. 

38 

I i
Therefore, the sensitivity calculations were carried out to investigate the influence of an increase in 

the calculated Hw 1 (tcal) coefficients of heat transfer from the rods to a steam flow on the axial 

distribution of the rod's wall temperatures in the uncovered part of the core model. 

The main goal of the sensitivity studies is an attempt to reduce large differences between code 

predictions for the axial profile of the rod's wall temperature TW (tlcal) and axial distribution of 

the measured rod's cladding temperatures TW (tOexp) in the uncovered part of the FA model at the 

initial time moment tOexp, and then during a "steady regime". 

The sensitivity calculations were performed for VTI test 7.12.15.4 using nodalization with 40 

volumes for the Core model and maximum user-specified time step dt max = 0.025 s, and also using 

fouling factor KHw1=3.0 to define the increased coefficients Hwl (tcal) of a heat transfer in the 

uncovered FA part. The results of the code simulation for the test 7.12.15.4 are presented on the 

Figures D-1+D-9 in the Appendix D. 

As seen, the results of the sensitivity study for the "initial steady state" and then for a "steady 

regime" are in good agreements with the test data about the main regime parameters: pressure Pup 

(tOexp), mass flow rate G (tOexp), heat flux qw (tOexp) and mixture level Lm (tOexp) in the core 

model (see Figures D-1, D-3, D-4, D-6, accordingly). Also, it provides the needed mass flow rate 

Gg (tOexp) of a generated steam flowing into the uncovered part of the core model under the test 

conditions. 

Using fouling factor Kivl=3.0 the code reasonably describes the behaviors of the rod's wall 

temperatures in the uncovered part of the FA model during the "steady regime" (see Fig.D-5, 

Fig.6.1)). Comparison of the base case (with KHwI=I.0) and sensitivity case (with KHw1=3.0) 

calculated axial profiles of rod's wall temperatures TW (tlcal) with the measured distribution of the 

rod's cladding temperatures for the initial time moment is shown in the Figure 6.1. In the case with 

KHwv=3.0 there is a good agreement between axial profile of the calculated rod's wall temperature 

TW (tlcal) and axial distribution of the measured temperatures TW (tOexp) in the uncovered part of 

the FA model.

39
>: 800 

S700~ 

600

500- pq 400 _ __ 

500 , , 

0 500 1000 1500 2000 2500 

Length (mmrr) 

Fig.6.1. Comparison of the base case (KHwI=l.0) and sensitivity case (K-w1=3.0) calculated axial 

profiles of rod's wall temperatures TW (tlcal) with the measured distribution of the rod's cladding 

temperatures for the initial steady state in the test 7.12.15.4. 

Thus, using fouling factor KHwl=3.0 the code gives a completely adequate simulation of the initial 

and boundary conditions and then of a steady regime for both the hydrodynamics and heat transfer 

process, realized in the uncovered part of the core model during VTI test 7.12.15.4. 

The sensitivity calculations were performed for VTI test 8.6.3.2 using nodalization with 40 volumes 

for the Core model and maximum user-specified time step dt max = 0.025 s, and also using fouling 

factor KHwl=3.0 to define the increased coefficients of heat transfer Hwl (tcal) in the uncovered FA 

part. The results of the code simulation for the test 8.6.3.2 are presented on the Figures D-10-D-18 

in the Appendix D. As seen, the results of the sensitivity study for the "initial steady state" and the 

"steady regime" are in good agreements with the test data about the main regime parameters. 

The results of sensitivity study and test data for VTI test 8.6.3.2 are presented as time-dependent 

curves within the time interval 1000 s for the "steady regime" on the Figures D-10÷D-18 in the 

Appendix D.

40
Using fouling factor KHwl=3.0 the code reasonably describes the behaviors of the rod's wall 

temperatures in the uncovered part of the FA model during a "steady regime" (see Fig.D-14, 

Fig.6.2). Comparison of the base case (with KHwl=I.0) and sensitivity case (with KHwl=3.0) 

calculated axial profiles of rod's wall temperatures TW (tical) with the measured distribution of the 

rod's cladding temperatures for the initial time moment is shown in the Figure 6.2.

Test 8.6.3.2 ncore=40 volumes

Tw coa KHwl=l.0 

Tw col KHWI= 3.O 

900

800

700

600

500-

400-

0 566 1000 1500 Length (mam)

RELAP5/MOD3.2.2

2000 2500

Fig.6.2. Comparison of the base case (KHwl=1.0) and sensitivity case (Kmwv=3.0) calculated axial 

profiles of the rod's wall temperatures TW (tlcal) with the measured distribution of rod's cladding 

temperatures for the initial steady state in the test 8.6.3.2. 

As seen, using fouling factor KHwl=3.0 the code reasonably describes the axial distribution of the 

rod's wall temperatures TW(tlcal) in the uncovered part of the FA model for the "initial steady 

state". 

Thus, using fouling factor KHWl=3.0 the code gives a completely adequate simulation of the initial 

and boundary conditions and then of a steady regime for both the hydrodynamics and heat transfer 

process, realized in the uncovered part of the core mode during VTI test 8.6.3.2. 

For example, the effect of the increase in the heat transfer coefficients (using KHwl=3.0) and of the 

implementation the real axial profile of the rod simulator temperatures in the Restart input deck on

41

00000 - Tw exp

e3 

E

1100-

I
the histories of the calculated rod's wall temperatures in the uncovered part of the FA model is 

shown in the Figure 6.3. In the case with KHwl=3.0 these histories of the rod's wall temperatures 

TW (tcal) are given in the Figure 6.3 within the time interval from tOcal = 0 s up to tical = 3000 s, 

the last corresponds to t0exp. 

200 Tes 8.6.3.2 ne=40 voiumes RELAP5/1OD3.2.2 

C071031 t 0071 36 071032 0071 37 071033 0071 38 

071034 0071 39 1Kw,,= 1.01 i 100 - - 107035 7---- 0071 40 

1000 K .T 

S900 

800/ 

700 . , . -

600 0 1000 2000 3000 4000 5000 6000 

Time (s, 

Fig. 6.3. The effect of the increase in the heat transfer coefficients Hw1 (tcal) and of the 

implementation real axial profile of the rod simulators in the Restart input deck on the histories of 

the calculated rod's wall temperatures TW (tcal) in the FA uncovered part. 

The code results for the "initial steady state" at the time tlcal=3000 s are in good agreements with 

the test data about the regime parameters. 

Then restarting from this completely adequate "initial steady state" at tcal = 3000 s and using 

fouling factor KHwv=l.0 which is pre-assigned for the base case calculations, we have run the 

transition to such a steady state in the loop at the time moment tcal=6000 s, which has to be 

adequate to the experimental " steady state" at the beginning of the test. Code simulation of this 

transient with KHwl=1.0 was realized during the time interval from tcal = 3000 s up to tcal = 6000 s 

to illustrate a complete stabilization of the calculated values for the regime parameters during the 

particular time interval.

42
The effect of the decrease in the heat transfer coefficients (with KHwl=l.0) and of the 

implementation a real axial profile of the rod simulator temperatures in the Restart input deck on the 

histories of the calculated rod's wall temperatures in the uncovered part of the FA model is shown 

in Fig. 6.3, too. In the case with Krw=l.0 the histories of the rod's wall temperatures TW (tcal) are 

given in the Figure 6.3 within the time interval from tcal = 3000 s up to tcal = 6000 s. 

As seen, restarting from needed "initial steady state", the rod simulator temperatures in the 

uncovered FA part begin to increase with the high rate after tcal=3000 s during the code simulation 

of the consequent regime with KHw1=l.0, which is recommended by the code developers for the 

base case calculation. As a consequence, a significant quantitative difference of the calculated and 

measured axial temperature profiles in the uncovered FA model was achieved again at the end of 

the transition to a "steady state" at tcal = 6000 s, which corresponds to the beginning of a "steady 

regime" in the test. This fact shows that initial temperature conditions in the FA model weakly 

influence on the code simulation of the heat transfer process in the partially uncovered core in 

considered "steady regime". 

The sensitivity studies show that the main reason for the deviations between experiment and 

calculations is the under estimation for the coefficients of heat transfer from the rod simulators to a 

steam in the uncovered part of the FA model under conditions of the transition mode of a steam 

flow in the channel. 

Comparison of the base case (KHwl=l.0) and sensitivity case (KHw,=3.0) calculated axial 

distributions of the heat transfer coefficients Hwl (tlcal) in the uncovered part of the FA model for 

the test 7.12.15.4 is shown in Fig.6.4. 

Comparison of the base case (KHw1=l.0) and sensitivity case (KHwI=3.0) calculated axial 

distributions of the heat transfer coefficients Hw 1 (tlcal) in the uncovered part of the FA model for 

the test 8.6.3.2 is shown in Fig.6.5.

43
* I 8125 

~100I 

50 

25

1800 1900 2000 2100 2200 2300 2400 2500 

Length (mr'n) 

Fig.6.4. Comparison of the base case (KHwv=l.0) and sensitivity case (Kmwl=3.0) calculated axial 

distributions of the heat transfer coefficients Hwl (tlcal) in the uncovered part of the FA model for 

the test 7.12.15.4. 

Test 8.6.3. 0 RELAPS/MOD3.2.2 

-, I• -IHTHTC Ir'F= .O 

400 

2001

0 

!80 ICCo 2000 21CC 2200 2300 240, 

ýength (mm)

Fig.6.5. Comparison of the base case (KHwl=l.0) and sensitivity case (KHwI=3.0) calculated axial 

distributions of the heat transfer coefficients Hwl (tlcal) in the uncovered part of the FA model for 

the test 8.6.3.2.

44
Conclusions for the sensitivity studies

* The sensitivity studies show, that the increase (with Kirwi=3.0) in calculated coefficients of heat 

transfer Hwl (tcal) in the uncovered part of the FA model results in a reasonable adequacy of the 

code simulation of the initial and boundary conditions for both the hydrodynamics and heat transfer 

process, realized in the uncovered part of the core model. Using fouling factor KFvl= 3 .0 and the 

implementation of a real (experimental) temperature profile for the FA model in the Restart input 

deck allow to reduce large differences between RELAP5/MOD3.2.2GAMMA predictions and test 

data for the axial temperature profile in the FA model for the initial time moment. 

* However starting from this needed "initial steady state", the rod simulator temperatures in the 

uncovered FA part begin to increase with the high rate during code simulation of the consequent 

"steady regime" with KHwl=1.0 which is recommended by the code developers. As a consequence, 

a significant quantitative difference of the calculated and measured axial temperature profiles in the 

uncovered FA model was achieved again at the end of the transient. 

9 Thus, the sensitivity studies show that the main reason for the deviations between experiments 

and calculations is the under estimation for coefficients of heat transfer from the rod simulators to a 

steam in the uncovered part of the FA model under conditions of the transition mode of a steam 

flow in the channel. Therefore, sensitivity calculations for the tests were performed using fouling 

factor KHWi=3.0 to define the increase in coefficients of heat transfer in the uncovered FA part. 

9 Using fouling factor KHwl=3.0 the code gives an adequate simulation of the initial and boundary 

conditions for both the hydrodynamics and heat transfer process, realized in the uncovered part of 

the core model. With KHwl=3.0 the code reasonably describes an axial distribution of the rod's wall 

temperatures in the uncovered part of the FA model for the "initial steady state", and then during 

the "steady regime" under considered conditions.

45
7. RUN STATISTICS 

The simulation model for 8.6.3.2 test includes: 

131 volumes, 129 junctions, 167 heat structures with 611 mesh points. 

There were the following resources been used for the calculation: 

Run time - CPU = 1305.91 s; 

Step number - DT = 40096; 

Volume number - C = 131. 

Calculation results of grind time (program efficiency factor) 

CPU- 103 

Grind time = = 0.2486 

C.DT 

For the calculations, it was used a computer IBM PC AT with processor INTEL Pentium 2 - 450. 

Windows-95 was used as an operating system. CPU-time and the integration step variations are 

presented in Figures 7.1 and 7.2, respectively.

Tes 6 4 "2

200 

0 0 200 400 600 Ti-e (s)

Fig.7.1. Execution times (CPU TIME) of the main variant computation for test 8.6.3.2.

Test 8.6 3.2 4RELAPS/AOD 3 . 2.2

0 03 

002

'0

Ti-, (s:

Fig.7.2. Integration step (DT) variations at the main variant computation for test 8.6.3.2. 

46

e EE)
8. SUMMARY OF CONCLUSIONS

e RELAP5/MOD3.2.2GAMMA and the base case methods of computer modeling of the 

experiments have provided adequate simulations of the initial and boundary conditions only for 

hydrodynamics, realized during the tests in steady regimes with steam-condensate natural 

circulation in the VVER-440 loop model. In these tests the transition mode of a steam flow is 

realized in the uncovered part of the FA model with corresponding Reynolds numbers Reg= Vg -Dh 

/Vg = 1860 - 830. 

* Shown is an insufficient code adequacy for the description of the rod's wall temperatures 

behaviors in the uncovered part of the FA model. There are significant quantitative differences of 

the axial profiles of the calculated and measured rod's wall temperatures in the uncovered part of 

the FA model in the base case calculations for these tests. 

The code over predicts rod's wall temperatures in the uncovered part of the FA model at the initial 

time moment, and then during "steady regimes". The calculated rod's wall temperatures are much 

higher (up to - 150 K) than measured ones at the FA outlet. This is the main problem of the code 

for the base case calculations for these tests. 

* The sensitivity studies have shown that the main reason for the deviations between experiments 

and calculations is the under estimation for the coefficients of heat transfer from the rod simulators 

to a steam in the uncovered part of the FA model under conditions of the transition mode of a steam 

flow in the channel. 

e The increase in calculated coefficients of heat transfer in the uncovered part of the FA model 

results in a reasonable adequacy of the code simulation of the initial and boundary conditions for 

both the hydrodynamics and heat transfer process, realized in the uncovered part of the core model. 

Using fouling factor KHwl=3.0 the code reasonably describes the axial distributions of the rod's 

wall temperatures in the uncovered part of the FA model for the initial steady states, and then 

during the steady regimes in considered tests.

47
REFERENCES

1. Gordon B.G., Pomelnikov V.N. Study of Heat Transfer at Small LOCAs. Thermophysical 

Aspects of VVER Safety. Proceedings of the International Symposium "Thermophysics-90", 

Volume 1, p. 255-262. 

2. Gordon B.G., Pomelnikov V.N. Study of Heat Transfer in the VVER Fuel Assembly at low mass 

flow. Journal "Atomic Energy", volume 68, April 1990, p. 288-291. 

3. V.G.Sorokin, A.V.Volosnikova, S.A.Vyatkin. Types of steels and alloys. M. Mashinostroenie, 

1989 (In Russian). 

4. Electrotechnical hand book. M.-L., GEI, 1962 (In Russian). 

5. RELAP5/MOD3 Code Manual. Volume 4: Models and Correlations. INEL-95/0174, 

NUREG/CR-5535. 1995. 

6. RELAP5/MOD3 Code Manual. Volume 2: User's Guide and Input Requirements INEL-95/0174, 

NUREG/CR-5535. 1995. 

7. V.A.Vinogradov, A.Y. Balykin. Computer code validation for transient analysis of VVER and 

RBMK reactors: Standard Problem INSCSP-V4 Analysis "Investigation of heat transfer for partly 

uncovered VVER-1000 core at the test facility KS (RRC KI), International Nuclear Center of 

Russia Minatom, Moscow, Russia, 2001, 167 p. 

8. V.A.Vinogradov, A.Y. Balykin. Analyses of KS-1 Experimental Data on the Behavior of the 

Heated Rod Temperatures in the Partially Uncovered VVER Core Model Using RELAP5/MOD3.2. 

International Agreement Report NUREG-IA-0169, November 1999. 

48
Appendix A 

Original Data Plots from the Tests

A-1
Test 7.12.54 m 2 

2

400

Lengt (rmm)

Fig.A-1. Experimental core axial distribution of rod's wall temperatures for test 7.12.15.4.

A-2

70(
0_ 

Q1100 

1000 

900 

800 

700 

600 

500 

400 

300

Test 8.6.3.2

U DUU IUUU I UU LUUU -DUL 

Length (mm)

Fig.A-2. Experimental core axial distribution of rod's wall temperatures for test 8.6.3.2.

A-3

U 

0 

00 Q) 

0o 0 

d'•f
Appendix B 

Base Case Results for Test 7.12.15.4

B-I
r-oý4-0 volumes, 0 R-LAP5VS/OD3.2.2 Test 7 12.15.4

40 

530 

a

20

1000 Time (sý

Fig.B-1. Comparison of the calculated Pup (tcal) and measured Pup (texp) pressure histories in the 

upper plenum model in experiment 7.12.15.4 

400 Test 7.1.2.154 no,,=40 volirnes, Kwj=i.0 RELAPS/MOD3.2.2 

395 , F c 

3 

21 

i30 

2g50

Time ( s

Fig.B-2. Calculated TF 

7.12.15.4.

(tcal) water temperature history at the inlet of FA channel in experiment

B-2
T• 71 ') IRAz

0.010

0.008 

ý'0.006 

0 

-0.004 

0.002 

0.000

0 200

Fig.B-3. Comparison of the calculated GL (tcal), Gg (tcal) and 

histories at the inlet of FA channel in experiment 7.12.15.4.

15000.

Test 7.12.15

measured G (texp) mass flow rate

n.o,.=40 volumes; Kw=I.0 RELAP5/MOD3.2.2

14U000 

Heat flux qw exp 

OEE=D Heat flux qw ccl (N

z 

I

12000 

11000 

10000

500 1000 1500 

Length (mm)

2000 2500

Fig.B-4. Comparison of the distributions of experimental qw (tOexp) and calculated qw (tlcal) 

specific heat fluxes from the outer surfaces of the rod simulators to a coolant on the FA height for 

the initial time moment in experiment 7.12.15.4.

B-3

G exp 

G C col 

C9 cal

400 600

Time (s)

800 1000

__ ___ ___ I __3 ___

f
Te 7..2 15 4 o es K K,,.=!40 0 RE.A 5/MOD302ý2 

0 71032 007 09 

8 7 7 K

'A A A A A A A A K. . K 

K

I -

II I V. 7] Vm m m I

400 600 800 100:

. e0 t 712.154 000 -i

-I.. 800 

700

600 

500 

400

0 20C

rc,=40 volumes K-= 1 .0 RE0AP 0/MOD3.2.2

I I

-71025 -+--i----- 0,171030 071026 -- C 71031 

7 * 029- 0 71034

400 T~ome (Sl

900 1Tes, 7.! 2.1 5.4 ic,• 0 

0071001 

0071002 

S007100 0071005

06o 800 1 000

.4oues; K,,,= 1 8RELAPS100/MOD3.2.2 

0071006 >6-66.6< 00007

- 671010

I I I

-,-'*----g+ -

400 800 Tire (9) 1 00C

Fig.B-5. Calculated TW (tcal) rod's wall temperatures histories in the upper, middle and bottom 

parts of the FA model in experiment 7.12.15.4.

B-4

8900 

Soo

~ LA E E- E ý

600 - 260

S600 

500 ' • ,• •

401

200

2fs 22R ý 2ýs ZN - - - - - - = --

• • ,r • F•, • r•

.30
n,,,=40 volumes; K_1,=1.0 RELAP5/MOO3.2.2- 1 100 Test 7.12.15.4

I00 1 n0t0 1(m00 Length (mnm)

2000 2500

Fig.B-6. Comparison of the axial profile of calculated rod's wall temperature Tw (t2cal) in the FA 

model and axial distribution of measured rod's cladding temperatures for test 7.12.15.4.

Test 7.12.15.4 n,•,.=40 volumes; K..,=1.0 RELAP5/MOD3.2.2

75 

50

25

00* 

75. 

iM : 

50

007103101 -H-- 0 C-- 7103601 I 007103201 >000< - 007103701 25- ,46#•X 007103301 A0e4ete - 0 7103801 - 007103401 -****- 0C 7103901 

007103501 5 -- 0C7104001 

0 - . . .. . . .

200 460

Time (s)

600

Fig.B-7. Histories of the calculated coefficients Hwl(tcal) of heat transfer from the rods to a vapor 

in the uncovered part of the FA model in experiment 7.12.15.4. 

B-5

1000 

900

•" 800 

- 700 

E 

S600 

500 

400

00000 fTw exp 

[:3EiET- Tw cal

HO

c~r

4 4 -

0

200

E 

I

0 8OO 1000

•1 II I

Test 7.12.15.4

r)

1

V
Jest 7.,2.'5 n,, =40 vouimes, K_

8000 

6000 

5000 

4000 

3000j 

2000 I 

~00C

.0 RELAP5/MOD3 2.2

0 50

Fig.B-8. Axial distribution of the calculated 

to a coolant for experiment 7.12.15.4.

coefficients Hwl(t2cal) of heat transfer from the rods

1 *Tesi,7.1, 15. t o/e v um. K .i 0 .LAPý MOQ 3.2. ,

-I

0.6

0.0

Time (s)

Fig.B-9. Calculated void fractions histories in the upper part of FA channel in experiment 7.12.15.4. 

B-6

oN 

E5

Length (-r.m

2000 1 000 "!500 2500
1.0 

0.8 

•'0.6 

-J 

w 

> 0.4 

0.2 

0.0 U LUU

n.•-.40 volumes. K~w,=t.O RELAP5/MOD3.2.2

40U

Time (s)

OUU 8UU IUU0

Fig.B- 10. Calculated Vg (tcal) vapor velocities histories in the upper part of FA channel in 

experiment 7.12.15.4. 

1.0 Test 7.12.15.4 ncore=40 volumes; KHw,=l0 RELA p 

0.8 

0.6 

0.4 

0.2 

0.0 1 ) E) G994 , , . .........

Fig.B-11. Calculated axial distribution of the void fractions in the FA channel in experiment 

7.12.15.4.

B-7

"-• 00724 G-KO<-• 00734 ,Jt 00726 >•9• ý - 00736 

00728 *A*i•t' 00738 

00730 • -00740

ITest 7.12.15.4
Test 7.2.,5.4 n ' volumes; K =,=.0 RELAP 0/MOD3.2.2 

4

e t000 Length 1500 (mram) 2000 2500

Fig.B-12. Calculated axial distribution of the vapor velocities in the FA channel at pressure 

Pup=27.3 bar and FA power W= 16.8 kW in experiment 7.12.15.4.

nF, =40 volumes. Ký,, t . RELAP5/MOD0. 7 U1 ..... 5/M__ _ 2 2.,

2100 2200 2300 

Length (Mm)

Fig.B-13. Axial distribution of the calculated vapor temperatures Tg (x) in the uncovered part of FA 

channel for the test 7.12.15.4. 

B-8

1I.

S0. 6 

0.4 

0.2

Test 7.12. 154

700 

600- Li 

CJ

400 

1800 1900

500

i

2500
Appendix C 

Base Case Results for Test 8.6.3.2

C-1
Test 8.6.6 .2 

S 4

4C

,ý_,=40 voidrues; K,,=].10 RELA% NMOD3.2.2 

exp E3 C 03 Pu

z.

2

4O0 800 100

Time (s)

Fig.C-1. Comparison of the calculated Pup 

upper plenum model in experiment 8.6.3.2. 

Test 8.6.3.2 

350 

C i

340

(tcal) and measured Pup (texp) pressure histories in the 

=40 volumes, K,=1_0 RELAP5/MOD3.2 2 

400 [] 80 1000 

40600 800 1000

Time (s)

Fig.C-2. Calculated TF(tcal) water temperature history at the inlet of FA channel in experiment 

8.6.3.2. 

C-2

I I ] I . . . . . . . . . . . . . . . . .

r, 20
0.010 

0.008 

~-0.006 

(0 

-0.004 

0.002 

0.000

G exp S2 G cal 

Gg cal 

0 200 400 600 800 10t 

Time (s)

Fig.C-3. Comparison of the calculated GL (tcal) , Gg (tcal) and measured G (texp) mass flow rate 

histories at the inlet of FA channel in experiment 8.6.3.2.

Test 8.6.3.2 n,,.,=40 volumes: K..,=l.0 RELAP5/MOD3.2.2

1000 1500 

Length (mm)

2000 2500

Fig.C-4. Comparison of the distributions of experimental qw (tOexp) and calculated qw (tlcal) 

specific heat fluxes from the outer surfaces of the rod simulators to a coolant on the FA height for 

the initial time moment in experiment 8.6.3.2.

C-3

O0

20000 

18000 

E 6000 

z • 14000

1 9nNN(

L- -+ I fl. -,J

--ý:E - Heat flux qw ci2

10000o-, 

0

,ý#e

I • l l ) i l l l l l l l l I I l • l l l l I I J l [ l l l t

T•f • • "• ?

500
" 2C

0C

700

Tioe (s

10(

900 

800 

700 

600

7et 6.632 rq___ =40oh-ono K..... 1

I4.7 S0071030 -

i1

400 

0 

900 Test 8.6.3.2

700 

S600 

50O 

300 

310

0071029 ,•* - 00710534

_- [ 1 : )( E~( ) )E < ) ( ) ( ) ( X X >

- ___ -" *O 1 

200 400

Týrne (s'

660 800 1000

Ti'e (S)

Fig.C-5. Calculated TW (tcal) rod's wall temperatures histories in the upper, middle and bottom 

parts of the FA model in experiment 8.6.3.2.

C-4

v
1100

1000

900" 

•" 800. 

% 700• 

Q0

5E

n.,.-=40 volumes; K-,==1.0 RELAP5/MOD3.2.2

600

500-_____ 

400 _____

1006 1500 

Length (mm)

Fig.C-6. Comparison of the axial profile of calculated rod's wall temperature TW (t2cal) in the FA 

model and axial distribution of measured rod's cladding temperatures for test 8.6.3.2.

500 

450 

400 

-350 

300 

E 

3 250 

S200 

150 

100 

50 

0

- -40 <.=1 (1 PFI AP/Aflfl)

- 00710310 - 0(7103601 

- 00710330' :etefe+- 0 7103801 

00710340 * -* 0 7- 7103901 

r-00710550 - 0XM 0(7104001 1 

0 200 400 600 800 10 

Time (s)

00

Fig.C-7. Histories of the calculated coefficients Hwl(tcal) of heat transfer from the rods to a vapor 

in the uncovered part of the FA model in experiment 8.6.3.2. 

C-5

00000 - Tw exp F Tw col a

ý 0 U

Test 8.6.,3.2

yjP (

0 500 20 00 25 00

T•f A R • "2
14000 Tes 8o6e 245 voIu21le K, 1 0 RELAP5 15 O>3 2 2

1200

500 10oo00 1500 

Lergto (2 m)

2000

Fig.C-8. Core axial distribution of the calculated coefficients Hwl(t2cal) of heat transfer from the 

rods to a coolant for experiment 8.6.3.2.

,TesLo 8.6•:.2 4 vuluml5; K- =1.,Q RELAP5IV0 D3.2.2,

00722 0 

0072 AOOý* 007368 

00728 -- 00738 00730 00740 

A A 

A A A I A A 

0~> ~~> > K K>1

U 200 400

Time (s)

600 800 10100

Fig.C-9. Calculated void fractions histories in the upper part of FA channel in experiment 8.6.3.2. 

C-6

Ž4 

6d 

3:

1000) 

800 

600 

40(2

o 1j 

-II 

o- 1!

400C 

20002

1)

1.0

4

02 

0.0

.. .T

I -It _ lltttj,ý, zzv_,=M5,ý - -

Test 8.6.3.2 n•,o: 40 volume.' K•vl=l 0 RELAP5,!MOD2.2 2

I 

I.L•

Q

I
1.0 

0.8 

0. .6 

> 0.4

0.2

0.0

0

- 00724 >0 tl- 00734 - 00726 XH4- 00736 

- 00728 * -- 00738 

- 00730 - 00740 

A A A A A a \A A A A 

? ? ? >, ),( • V4

200 400 600 8O0

Fig.C-10. Calculated Vg (tcal) vapor velocities histories in the upper part of FA channel in 

experiment 8.6.3.2.

1.0 

0.8 

0.6 

U 

0.4 

0.2

0.0

Test 8.6.3.2 n...o40 volumes. K ,=I.0 RELAP5MOQD39._9

L0 1500 Length (mm)

Fig.C-11. Calculated axial distribution of the void fractions in the FA channel 

8.6.3.2.

in experiment

C-7

iobo

------- GE 

Test 8 6.3 2 n =40 volumes; K wj=1.0 RELAA MOD ý 9 9 

E)GEDGE)989

Test 8.6.3.2 no,,,=40 volumes; Kw=11.0 RELAP5/MOD3.2.2

1000

0 500 100 2000 250C
Test 8.5.3.2 

27 nr,_40 vo!,jmes, KHv,= .0 RELAPV MC'OS 2.2

---- L

C

0 500 10e00 15100 Length (nram)

Fig.C-12. Calculated axial distribution of the vapor velocities 

Pup=27.3 bar and FA power W=16.8 kW in experiment 8.6.3.2.

T 

2000 2500 

in the FA channel at pressure

1000-, Test 8.6.3.2 nroý40 volumes, K., 

mC0

1800 1900 2000 2100 2200 Length (--)

RE AP SVtvO D.2.2

2300 2400 250-

Fig.C-13. Axial distribution of the calculated vapor temperatures Tg (x) in the uncovered part of FA 

channel for the test 8.6.3.2.

C-8

.6 

.4

• " : / rI

6FO I
Appendix D 

Sensitivity Studies Results

D-1
60 Test Tq 7.',2.15.4 ioe ~ 40 v ~ lm s K_•,.=-3.0 % R-, h- A.P/ý ýV •~jz.r D , 4 RM~

® 30

Time (s)

Fig.D-1. Comparison of the calculated Pup (tcal) and measured Pup (texp) pressure histories in the 

upper plenum model in experiment 7.12.15.4.

o.0C0 

0.008 

- 0.006 

0 0 

0.002 

C.OO0

Fig.D-2. Comparison of the calculated GL (tcal) , Gg (tcal) and measured G (texp) mass flow rate 

histories at the inlet of the FA channel in experiment 7.12.15.4.

D-2

Time
n,,,e=40 volumes; K~w-=3.0 'RELAPS/MO3.2.2 15000 Test 7.12.1E

1400n I5

I I 

500

Heat fluý qw exp 

Heat fluý qw cal

1000 1500 

Length (mm)

2000 2500

Fig.D-3. Comparison of the distributions of experimental qw (tOexp) and calculated qw (tlcal) 

specific heat fluxes from the outer surfaces of the rod simulators to a coolant on the FA height for 

the initial time moment in experiment 7.12.15.4.

Test 7.12.15.4 nco,e=40 volumes; Krwi=3.0 RELAP5/MOD3.2.2

1900 2000 2100 2200 2300 

Length (mm)

2400 2500

Fig.D-4. Axial distribution of the calculated vapor temperatures Tg (x) in the uncovered part of the 

FA channel at KHwI=3.0 for the test 7.12.15.4.

D-3

S13000 

z 

S12000 

I 

11000

0

OUu

•70C

0 

" 600-

400 -r 1800

_1_ L 

4 4. 4 --I- F 4 _______

q0t) •llltI •
20C 

110O 

'0000 

900 

800 

7 0C 

600

000 

900 

800

Test 7 1215.4 n,, =40 volumes; K_..30 ELAPS/MOD3.2.2 

E 0 02 " 007.037 0 7133 O0071038 i 

i 0071034 0071039 

=(0'4 6• b I,-- fn= •I }• 

1 ! So I 0IC Time (s) 

Test 7. 12. 15.4 no,=4-O volumes; Kw= 3,0 RELAP5/.\OD3.2 2

4 1

SJ 

700 

Soo 

500R Ik 

400 

0 

900 Test 7 12v! 

800 

707 

600 

400 

4 -04

0

0 71026 >ee C1 71 031: 

071028 ** _ 0071063 071029 5& - O7 7:34

200 a00 600

Ins (s

Fig.D-5. Calculated TW(tcal) rod's wall temperatures histories in the upper, middle and bottom 

parts of the FA model in experiment 7.12.15.4.

D-4

1.

86o 1C Time (s

i 

I I ..

11
0

n,,,,=40 volumes; K_ 1=3.0 RELAP5/MOD3.2.2

500 1000 1500 

Length (mm)

2000 2500

Fig.D-6. Comparison of the axial profile of calculated rod's wall temperature TW (tlcal) at 

KHwl=3.0 in the FA model and axial distribution of measured rod's cladding temperatures for test 

7.12.15.4. 

Test 7.12.15 n,,,=40 volumes; K-,=3.0 RELAP5/MOO3.2.2 - r r -I - -- r -- 1 T T 1

5- _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ I ___ _ __ ___ __ _ ___ _ _ _ ___

1900 2000 2100 2200 

Length (mm)

1800 2300 2400 2500

Fig.D-7. Axial distribution of the calculated coefficients Hw 1 (t2cal) of heat transfer from the rods 

to a coolant at KHwl=3.0 in the upper part of the FA model for experiment 7.12.15.4.

D-5

1100 

1000 

900

S 

2 

E Q,

800 

700 

600j 

500

00000 j Tw exp 

D D Tw col

I __ _ _ __I_ _ __ _ __ _ _ _ __ _ _ _

300

200

175 

150 

(4 125 

E 

• 100

- 7 3:

5' 

2.

Test 7.12.15.4

S 

/1 A¢', 

t
1 Test 7.12 15.4 

1.0

0.6 

0.4 

0.2 

0.0

n,,,=4C. vo~umnes, K.:=3.0 ; 4P-/\

Length (mnm)

Fig.D-8. Calculated 

7.12.15.4. 

1 0 

08 

0.6 

> . w

core axial distribution of the void fractions in the FA channel in experiment

0

D e 500 

-engtv- (mr'n)

Fig.D-9. Calculated core axial distribution of the vapor velocities in the FA channel at pressure 

Pup=27.3 bar and FA power W=16.8 kW in experiment 7.12.15.4.

D-6
n,,,,=40 volumes; Kwl=3.0 RELAP5/MOD3.2.2

60

60O 

4 n) . . . . . ... . . . . . . . . . . . . . .. . . . . .

26o0 46o

Time (s)

600 800 1000

Fig.D-10. Comparison of the calculated Pup (tcal) and measured Pup (texp) pressure histories in the 

upper plenum model in experiment 8.6.3.2.

0.010

0.008 

0.006 

0 

o 

- 0.004 

0.002 

0.000

Test 8.6.3.2 ncoe=40 volumes; KHw=3 0 RELAPS/MOD3.2.2 

G exp 

LI G col 

LS N Gg cal 

0 200 400 600 800 10O 

Time (s)

O0

Fig.D- 11. Comparison of the calculated GL (tcal) , Gg (tcal) and measured G (texp) mass flow rate 

histories at the inlet of the FA channel in experiment 8.6.3.2.

D-7

Pup exp 

Pup col

"0" 

.0 

0) 

0_

Test 8.6.3.2 1 AN)

I
I 

20000

1'z 

7

12000

1000

Length rr

50 2000 2500

Fig.D-12. Comparison of the distributions of experimental qw (tOexp) and calculated qw (tlcal) 

specific heat fluxes from the outer surfaces of the rod simulators to a coolant on the FA height for 

the initial time moment in experiment 8.6.3.2. 

Test 8.6.3 2 nr,,=40 vol.n es; K,,,,=3.0 k .LAPn ,2OD32.2 

911 

7 

800 

7- 00 

6-00 

1800 .190 2000 2100 2200 2300 2Z'00 2500 

Length (mr-} 

Fig.D- 13. Axial distribution of the calculated vapor temperatures Tg (x) in the uncovered part of the 

FA channel at KHwI=3.0 for the test 8.6.3.2.

D-8

JOC
0

3: 

0

3:

3:

-, -An V--9 10 srI 455 kflr1fl9 -, -,

1200 es _ _ _eooo -0 D71032 0071036 

071033 0071038 

0 71034 0071039 

1071035 0071040 

1 100 

1000 

900 

700 

0 200 400 600 600 10( 

Time (s) 

1000 Test 8.6.3.2 n..,.=40 volumes; K.-=3.0 RELAP5/MOD3.2.2 

10071 

0071025 -H--H-- 0071030 0071026 >,-$GO - 0071031 900 --- ~ O7 32--- 0071026 ý * 0071033 0071029 5/'•-- 0071034 

800_ 

700 _ 

600 < X __________"_< , f, > 

500 

400 0 200 400 600 800 10( Time (s) 

90 Test 8.6.3.2 nc,,=40 volumes; K-w=3.0 RELAPS/MOD3.2.2 

0071001 1 - 0071006 0071002 )G <-- 0071007 0071003 4 -- 0071008 Soo- T 0:0,2 10_13310 

0071005 0071010 

700 

600

500 

400 = 0 RE. 

'300-

Time (s)

Fig.D-14. Histories of the calculated TW (tcal) rod's wall temperatures in the upper, middle and 

bottom of the FA model in experiment 8.6.3.2.

D-9

0 200 400 600 Soo 1000
e 2,-=d-0 volumes; K_-3.39 RE-LAP5iMODS.2.2

E 0

0oo0 1500 

Lencgh (,m)

2500

Fig.D-15. Comparison of the axial profile of calculated rod's wall temperature TW (t2cal) at 

KHW1=3.0 in the FA model and axial distribution of measured rod's cladding temperatures for test 

8.6.3.2. 

Test 8.6.3. n,,,=40 vo:umes; Ký-=3.0 RELAP5/MOD3.2.2 

I Ii 

4500 

-250 

. . . 2o o0 0 

1800 2000 2100 220r ' 0 250 

Fig.D-16. Axial distribution of the calculated coefficients HwlI(t2cal) of heat transfer from the rods 

to a coolant in the upper part of the PA model for experiment 8.6.3.2.

D-10

Test 8.6.3.2
--.,,fl V -O PAO/,AOFV'.9')

1.0

0.8 

0.6 

(-5 

0.4 

0.2 

0.0

0 500 1000 1500 

Length (mm)

2000 250(

Fig.D-17. Calculated axial distribution of the void fractions in the FA channel in experiment 

8.6.3.2.

1.0

0.8 

('0.6 

> 0.4 

0.2 

0.0

Test 8.6.3.2 nco,e=40 volumes; Kw=,3.0 RELAP5/MOD3.2.2 

n3

1000 150( Length (mm)

Fig.D- 18. Calculated axial distribution of the vapor velocities in the FA channel at pressure 

Pup=27.3 bar and FA power W=16.8 kW in experiment 8.6.3.2.

D-11

est 8.6.3.22 n,,,,= A 0 vournes; I v HW1 = 'ý (n) REE I A 

e e E)eeee

50 2000 2500
Appendix E 

Base Case input deck listing for Test 8.6.3.2

E-1
=vti test 

"* Assessment of RELAP5/MOD3.2.2GAMMA "* against VTI VVER 8.6.3.2 test "* Initial conditions "* FA model power = 22,97 kWt "* UP outlet pressure = 7.01 MPa 

*0000 100 new stdy-st 

0000100 new transnt *00001(01 inp-chk 

0000102 si si 

0000104 *cmpress 

110 air 

* TIME STEPS CONTROL CARDS 

*0000201 10. 1.0-6 0.00025 14003 100 4000 40000 

00002013000. 1.0-6 0.025 14003 100 4000 40000 

* PRIMARY CIRCUIT 

* Lower Plenum 

- ------------------------

0050000 lowr pipe 

0050001 2 

0050101 21.1-3 2 

0050301 0.272 2 

0050601 90.0 2 

0050801 5.0-5 0.164 2 

0050901 0.0 0.0 1 

0051001000000 2 

00511010000000 1 

0051201 103 .

7 02589e+07 344.996 0.0 0.0 0.0 1 

0051202 103 .

7

0

2 3 2 8e+07 348.225 0.0 0.0 0.0 2 

00513000 

0051301 -3. 8

9245e-08 -3- 8 9

245e-08 0.0 1 

00514010.1640.0 1.0 1.0 1 

10052000 23200.082 

10052100 0 1 

10052101 1 0.086 1 0.09 

10052201 1 2 

10052301 0.02 

10052400 -1 

10052401 345.00 345.00 345.00 

10052402 348.22 348.22 348.22 

*10052401 340.0 3 

10052501 005010000 10000 1 10.272 2 

10052601 0 0 0000 1 0.272 2 

10052701 0 0.0 0.0 0.0 2 

10052801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 2 

0060000 incore sngljun 

0060101005010000 007000000 0.0 0.0 0.0 0000000 

0060201 0 4

.

7 0647e-03 4

.

7

0647e-03 0.0 

*------------------------------------ --

* Core Model 

*------------------------------- - - - - - - -----------

0070000 core pipe 

0070001 42 

0070101 1.478-3 42 

0070301 0.0975 2 

0070302 0.06 38 

0070303 0.0725 40 

0070304 0.0625 42 

0070601 90. 42 

0070801 1.0-5 8.02-3 42 

00709010.0 0.0 1 

0070902 0.27 0.27 2 

0070903 0.0 0.0 3 

0070904 0.0 0.0 4 

0070905 0.0 0.0 5 

0070906 0.27 0.27 6 

0070907 0.0 0.0 7 

0070908 0.0 0.0 8 

0070909 0.0 0.0 9 

0070910 0.27 0.27 10 

00709110.0 0.0 11 

00709120.0 0.0 12 

0070913 0.0 0.0 13 

0070914 0.27 0.27 14

0070915 0.0 0.0 15 

00709160.0 0.0 16 

00709170.0 0.0 17 

0070918 0.27 0.27 18 

00709190.0 0.0 19 

0070920 0.0 0.0 20 

00709210.0 0.0 21 

0070922 0.27 0.27 22 

0070923 0.0 0.0 23 

0070924 0.0 0.0 24 

0070925 0.0 0.0 25 

0070926 0.27 0.27 26 

0070927 0-0 0.0 27 

0070928 0.0 0.0 28 

0070929 0.0 0.0 29 

0070930 0.27 0.27 30 

0070931 0.0 0.0 31 

0070932 0.0 0.0 32 

0070933 0.0 0.0 33 

0070934 0.27 0.27 34 

0070935 0.0 0.0 35 

0070936 0.0 0.0 36 

0070937 0.0 0.0 37 

0070938 0.27 0.27 38 

0070939 0.0 0.0 39 

0070940 0.0 0.0 40 

0070941 0.0 0.0 41 

0071001 1010042 

0071101 000100041 

0071201 103.702152e+07 377.452 0.0 0.0 0.0 1 

0071202 103 .702061e+07 406.842 0.0 0.0 0.0 2 

0071203 103. 7

01989e+07 424.966 0.0 0.0 0.0 3 

0071204 103.701936e+07 443.082 0.0 0.0 0.0 4 

0071205 103 .701883e+07 461.178 0.0 0.0 0.0 5 

0071206 103 .701832e+07 478.962 0.0 0.0 0.0 6 

0071207 103.701782e+07 496.343 0.0 0.0 0.0 7 

0071208 103.701733e+07 513.325 0.0 0.0 0.0 8 

0071209 103 .701686e+07 529.761 0.0 0.0 0.0 9 

0071210 103 .701640e+07 545.477 0.0 0.0 0.0 10 

0071211 100. 7

01596e+0

7 .125550e+07 .258170e+07 .

2

60623e-02 0.0 11 0071212 100.701552e+07 .12

58 6 0e+07 .

2

5

8 170e+07 .207902e-01 0.0 12 0071213 100.701510e+07 .125870e+07 .

2

58170e+07 .391013e-01 0.0 13 0071214 100.701469e+07 .125870e+07 .258170e+07 .

5 6 7 6

85e-01 0.0 14 0071215 100.701428e+07 .125870e+07 .258170e+07 .

7 36818e-01 0.0 15 0071216 100.701388e+07 .125870e+07 .258170e+07 .

9

00012e-01 0.0 16 0071217 100. 7

01348e+07 .125860e+07 .

2

581 7

0e+07 .105740 0,017 0071218 100. 7

01309e+07 .125860e+07 .258170e+07 .121060 0.018 0071219 100.701271e+07 .125860e+07 .258170e+07 .135700 0.019 0071220 100.701233e+07 .125860e+07 .258170e+07 .150000 0.020 

0071221 100.701196e+07 .125860e+07 .258170e+07 .163860 0.021 0071222 100.70 1160e+07 .125850e+07 .258170e+07 .177520 0.022 0071223 100.701124e+07 .125850e+07 .258170e+07 .190480 0.023 

0071224 100.701088e+07 .125850e+07 .258170e+07 .203260 0.024 0071225 100.701053e+07 .125850e+07 .258170e+07 .215650 0.025 

0071226 100.701019e+07 .125850e+07 .258170e+07 .228080 0.026 0071227 100.700985e+07 .125850e+07 .258170e+07 .239170 0.0 27 0071228 100.700952e+07 .125840e+07 .258170e+07 .254270 0.028 0071229 100.700918e+07 .125840e+07 .258180e+07 .240130 0.029 0071230 100.700889e+07 .125840e+07 .258180e+07 .463610 0.030 0071231 100.700876e+07 .125840e+07 .264490e+07 1.00000 0.0 31 0071232 100.700874e+07 .125840e+07 .27 1020e+07 1.00000 0.0 32 0071233 100.700873e+07 .125840e+07 .277590e+07 1.00000 0-033 0071234 100. 7 00871e+07 .125840e+07 .284190e+07 1.00000 0.034 0071235 100.700870e+07 .125840e+07 .290850e+07 1.00000 0.035 0071236 100.700868e+07 .125840e+07 -

2 9 7 540e+07 1.00000 0.036 0071237 100.700867e+07 .125840e+07 .304330e+07 1.00000 0.037 0071238 100.700866e+07 .125840e+07 .311220e+07 1.00000 0.038 0071239 100.700864e+07 .125840e+07 .319640e+07 1.00000 0.039 0071240 100.700863e+07 .125840e+07 .328140e+07 1.00000 0.040 0071241 100,700862e+07 .125840e+07 .

3 2

7760e+07 1.00000 0.041 

0071242 100.700861e+07 .125840e+07 .327370e+07 1.00000 0.042 00713000 

0071301 4.80217e-03 4.80217e-03 0.0 01 

0071302 4.92188e-03 4.92188e-03 0.0 02 

0071303 5.00835e-03 5.00835e-03 0.0 03 

0071304 5.10578e-03 5.10578e-03 0.0 04 

0071305 5.21578e-03 5-21578e-03 0.0 05 

0071306 5.33863e-03 5.33863e-03 0.006 

0071307 5.47606e-03 5.47606e-03 0.007 

0071308 5.63140e-03 5.63140e-030.008 

0071309 5.80 7

83e-03 5.80 7 83e-03 0.0 09 

0071310 6.00949e-03 0.12846 0,0 10 

0071311 6.18187e-03 0.34266 0.0 11 

0071312 5.98735e-03 0.34755 0.0 12 

0071313 5.76625e-03 0.35301 0.0 13

E-2
0071314 5.53664e-03 0.35902 0.0 14 

0071315 5.29519e-03 0.36587 0.0 15 

0071316 5.04039e-03 0.37263 0.0 16 

0071317 4.77064e-03 0.37942 0.0 17 

0071318 4.48620e-03 0.38578 0.0 18 

0071319 4.18582e-03 0.39270 0.0 19 

0071320 3.87177e-03 0.39920 0.020 

0071321 3.54425e-03 0.40566 0.021 

0071322 3.20487e-03 0.41156 0.022 

0071323 2.85219e-03 0.41816 0.023 

0071324 2.48868e-03 0.42431 0.024 

0071325 2.11390e-03 0.43049 0.025 

0071326 1.72878e-03 0.43592 0.026 

0071327 1.33018e-03 0.44325 0.027 

0071328 9.23651e-04 0.44285 0.028 

0071329 4.90328e.04 0.49636 0.029 

0071330 0.27500 0.27139 0.030 

0071331 0.13770 0.13770 0.0 31 

0071332 0.15003 0.15003 0.032 

0071333 0.16272 0.16272 0.033 

0071334 0.17566 0.17566 0.034 

0071335 0.18884 0.18884 0.035 

0071336 0.20216 0.20216 0.0 36 

0071337 0.21539 0.21539 0.037 

0071338 0.22837 0.22837 0.038 

0071339 0.24387 0.24387 0.039 

0071340 0.25918 0.25918 0.040 

0071341 0.25849 0.25849 0.041 

00714018.02-3 0.0 1.000 1.00 41 

10071000 405200.0 

10071100 0 1 

10071101 1 0.00165 10.0028 10.00405 10.00455 

10071201 1 133 14 

10071301 1.010.04 

10071400 -1 

10071401419.04 416.85 402.02 391.55 391.03 

10071402 447.81445.66 430.64 420.04 419.52 

10071403 465.80 463.68 448.49 437.77 437.26 

10071404 483.77 481.68 466.36 455.55 455.04 

10071405 501.86 499.79 484.31473.39 472.89 

10071406 519.29 517.26 501.78 490.86 490.37 

10071407 536.36 534.36 518.89 507.96 507.48 

10071408 553.03 551.06 535.59 524.66 524.19 

10071409 569.12 567.19 551.71 540.79 540.33 

10071410 584.48 582.58 567.11 556.18 555.73 

10071411 589.19 587.30 571.82 560.90 560.44 

10071412 589.22 587.32 571.85 560.92 560.47 

10071413 589.21 587.32 571.85 560.92 560.47 

10071414 589.21587.31 571.84 560.92 560.46 

10071415 589.20 587.31 571.84 560.91 560.46 

10071416 589.20587.31571.83 560.91560.45 

10071417 589.19 587.30 571.83 560.90 560.45 

10071418 589.19 587.30 571.82 560.90 560.44 

10071419 589.18 587.29 571.82 560.89 560.44 

10071420 589.18 587.29 571.81560.89 560.43 

10071421 589.17 587.28 571.81 560.88 560.43 

10071422 589.17 587.28 571.80 560.88 560.42 

10071423 589.16 587.27 571.80560.87 560.42 

10071424 589.16 587.27 571.79 560.87 560.41 

10071425 589.15 587.26 571.79 560.86 560.41 

10071426 589.15 587.26 571.78 560.86 560.40 

10071427 589.14 587.25 571.78 560.85 560.40 

10071428 589.14 587.25 571.77 560.85 560.39 

10071429 589.14 587.24 571.77 560.84 560.39 

10071430 589.10 587.21571.74 560.81 560.36 

10071431 697.32 695.48 679.49 668.19 667.76 

10071432 740.69 738.85 722.26 710.54 710.10 

10071433 784.99 783.19 766.36 754.47 754.04 

10071434 830.62 828.87 811.80 799.75 799.33 

10071435 877.01 875.30 857.98 845.74 845.33 

10071436 922.43 920.75 903.21 890.82 890.43 

10071437 968.32 966.64 948.84 936.27 935.87 

10071438 1015.0 1013.4 995.34 982.60 982.21 

10071439 1067.1 1065.5 1047.2 1034.2 1033.9 

10071440 1118.3 1116.8 1098.2 1085.2 1084.8 

*10071401 559.05 

10071501 000 1 1.8525 2 

10071502 0001 1.1438 

10071503 000 1 1.377540 

10071601 007010000 10000 110 1 1.8525 2 

10071602 007030000 10000 110 1 1.14 38 

10071603 007390000 10000 110 1 1.3775 40 

10071701 001 3.634569e-02 0.0 0.0 1 

10071702 001 3.681150e-02 0.0 0.0 2

10071703 001 2.290184e-02 0.0 0.0 3 

10071704 001 2.309970e-02 0.0 0.0 4 

10071705 001 2.333816e-02 0.0 0.0 5 

10071706 001 2.333816e-020.00.0 6 

10071707 001 2.333816e-02 0.0 0.0 7 

10071708 001 2.333816e-020.0 0.0 8 

10071709 001 2.333816e-020.0 0.0 9 

10071710 001 2.333816e-02 0.0 0.0 10 

10071711 001 2.333816e-02 0.0 0.0 11 

10071712 001 2.333816e-02 0.0 0.0 12 

10071713 001 2.333816e-02 0.0 0.0 13 

10071714 001 2.333816e-02 0.0 0.0 14 

10071715 001 2.333816e-02 0.0 0.0 15 

10071716 001 2.333816e-02 0.0 0.0 16 

10071717 001 2.333816e-02 0.0 0.0 17 

10071718 001 2.333816e-02 0.0 0.0 18 

10071719 001 2.333816e-02 0.0 0.0 19 

10071720 001 2.333816e-02 0.0 0.0 20 

10071721 001 2.333816e-02 0.0 0.0 21 

10071722 001 2.333816e-02 0.0 0.0 22 

10071723 001 2.333816e-02 0.0 0.0 23 

10071724 001 2.333816e-02 0.0 0.0 24 

10071725 001 2.333816e-02 0.0 0.0 25 

10071726 001 2.333816e-02 0.0 0.0 26 

10071727 001 2.333816e-02 0.0 0.0 27 

10071728 001 2.333816e-02 0.0 0.0 28 

10071729 001 2.333816e-02 0.0 0.0 29 

10071730 001 2.333816e-02 0.0 0.0 30 

10071731 001 2.411948e-02 0.0 0.031 

10071732 001 2.502257e-02 0.0 0.0 32 

10071733 001 2.539293e-02 0.0 0.0 33 

10071734 001 2.574808e-02 0.0 0.0 34 

10071735 001 2.613620e-02 0.0 0.0 35 

10071736 001 2.645837e-02 0.0 0.0 36 

10071737 001 2.685410e-02 0.0 0.0 37 

10071738 001 2.721940e-02 0.0 0.0 38 

10071739 001 3.334989e-02 0.0 0.0 39 

10071740 001 3.374837e-02 0.00.040 

10071900 1 

100719010.0109 0.04875 2.45125 0.04875 0.14625 0.27 0.27 1.0 0.125 1.34 1.0 

1 

10071902 0.0109 0.14625 2.35375 0.14625 0.04875 0.27 0.27 1.0 0.125 1.34 1.0 

2 

10071903 0.0109 0.2256 2.2744 0.03 0.21 0.27 0.27 1.0 0.125 1.34 1.0 3 

10071904 0.0109 0.2856 2.2144 0.09 0.15 0.27 0.27 1.0 0.125 1.34 1.0 4 

10071905 0.0109 0.3456 2.1544 0.15 0.09 0.27 0.27 1.0 0.125 1.34 1.0 5 

100719060.01090.4056 2.0944 0.21 0.03 0.27 0.27 1.00.125 1.34 1.0 6 

10071907 0.0109 0.4656 2.0344 0.03 0.21 0.27 0.27 1.0 0.125 1.34 1.0 7 

10071908 0.0109 0.5256 1.9744 0.09 0.15 0.27 0.27 1.0 0.125 1.34 1.0 8 

10071909 0.0109 0.5856 1.9144 0.15 0.09 0.27 0.27 1.0 0.125 1.34 1.0 9 

10071910 0.0109 0.6456 1.8544 0.210.03 0.27 0.27 1.0 0.125 1.34 1.0 10 

100719110.0109 0.7056 1.7944 0.03 0.210.27 0.27 1.0 0.125 1.34 1.0 11 

10071912 0.0109 0.7656 1.7344 0.09 0.15 0.27 0.27 1.0 0.125 1.34 1.0 12 

10071913 0.0109 0.8256 1.6744 0.15 0.09 0.27 0.27 1.00.125 1.34 1.0 13 

10071914 0.0109 0.8856 1.6144 0.210.03 0.27 0.27 1.00.125 1.34 1.0 14 

10071915 0.0109 0.9456 1.5544 0.03 0.210.27 0.27 1.0 0.125 1.34 1.0 15 

10071916 0.0109 1.0056 1.4944 0.09 0.15 0.27 0.27 1.0 0.125 1.34 1.0 16 

10071917 0.0109 1.0656 1.4344 0.15 0.09 0.27 0.27 1.0 0.125 1.34 1.0 17 

10071918 0.0109 1.1256 1.3744 0.21 0.03 0.27 0.27 1.0 0.125 1.34 1.0 18 

10071919 0.0109 1.1856 1.3144 0.03 0.21 0.27 0.27 1.0 0.125 1.34 1.0 19 

10071920 0.0109 1.2456 1.2544 0.09 0.15 0.27 0.27 1.0 0.125 1.34 1.0 20 

100719210.0109 1.3256 1.1944 0. 15 0.09 0.27 0.27 1.0 0.125 1.34 1.0 21 

10071922 0.0109 1.3856 1.1344 0.21 0.03 0.27 0.27 1.0 0.125 1.34 1.0 22 

10071923 0.0109 1.4456 1.0744 0.03 0.21 0.27 0.27 1.0 0.125 1.34 1.0 23 

10071924 0.0109 1.5056 1.0144 0.09 0.15 0.27 0.27 1.0 0.125 1.34 1.0 24 

10071925 0.0109 1.5656 0.9544 0.15 0.09 0.27 0.27 1.0 0.125 1.34 1.0 25 

10071926 0.0109 1.6256 0.8944 0.21 0.03 0.27 0.27 1.0 0.125 1.34 1.026 

10071927 0.0109 1.6856 0.8344 0.03 0.21 0.27 0.27 1.0 0.125 1.34 1.0 27 

10071928 0.0109 1.7456 0.7744 0.09 0.15 0.27 0.27 1.0 0.125 1.34 1.0 28 

10071929 0.0109 1.8056 0.7144 0.15 0.09 0.27 0.27 1.0 0.125 1.34 1.0 29 

10071930 0.0109 1.8656 0.6544 0.210.03 0.27 0.27 1.0 0.125 1.34 1.0 30 

10071931 0.0109 1.9256 0.5944 0.03 0.21 0.27 0.27 1.0 0.125 1.34 1.0 31 

10071932 0.0109 1.9856 0.5344 0.09 0.15 0.27 0.27 1.0 0.125 1.34 1.0 32 

10071933 0.0109 2.0456 0.4744 0.15 0.09 0.27 0.27 1.0 0.125 1.34 1.0 33 

10071934 0.0109 2.1056 0.4144 0.210.03 0.27 0.27 1.0 0.125 1.34 1.0 34 

10071935 0.01092.1656 0.3544 0.03 0.210.27 0.27 1.00.125 1.34 1.035 

10071936 0.0109 2.2256 0.2944 0.09 0.15 0.27 0.27 1.0 0.125 1.34 1.0 36 

10071937 0.0109 2.2856 0.2344 0.15 0.09 0.27 0.27 1.0 0.125 1.34 1.0 37 

10071938 0.0109 2.3456 0.1744 0.210.03 0.27 0.27 1.0 0.125 1.34 1.0 38 

10071939 0.0109 2.41185 0.08815 0.01565 0.08815 0.27 0.27 1.0 0.125 1.34 1.0 

39 

10071940 0.0109 2.48435 0.01565 0.08815 0.01565 0.27 0.27 1.0 0.125 1.34 1.0 

40 

10072000 42 42 0 0.028

E-3
10072100 0 1 

10072101 1 0.040 1 0.0535 

10072102 1 0.0635 

10072201 2 12213 

10072301 0.03 

10072400 -1 

10072401 377.24 376.59 376.18 376.17 

10072402 406.89 407.00 407.08 407.08 

10072403 425.15 425.85 426.31 426.32 

10072404 443.40 444.81 445.74 445.75 

10072405 461.62 463.89 465.36 465.38 

10072406 479.37 481.54 482.95 482.96 

10072407 496.71 498.65 499.91 499.93 

10072408 513.63 515.25 516.31 516.32 

10072409 530.00 531.22 532.02 532.03 

10072410 545.63 546.37.546.88 546.88 

10072411558.51558.59 55865 558.65 

10072412 559.08 559.13 559.16 559.16 

10072413 559.10 559.14 559.17 559.17 

10072414 559.09 559.14 559.17 559.17 

10072415 559.09 559.14 559.17 559.17 

10072416 559.09 559.13 559.17 559.17 

10072417 559.08 559.13 559.17 559.17 

10072418 559.08 559.13 559.17 559.17 

10072419 559.08 559.13 559.16 559.16 

10072420 559.07 559.12 559.16 559.16 

10072421559.07 559.12 559.16 559.16 

10072422 559.07 559.12 559.15 559.16 

10072423 559.06 559.11 559.15 559.15 

10072424 559.06 559.11 559.15 559.15 

10072425 559.06 559.11559.15 559.15 

10072426 559.05 559.10 559.14 559.14 

10072427 559.05 559.10 559.14 559.14 

10072428 559.05 559.10 559.14 559.14 

10072429 559.04 559.09 559.13 559.13 

10072430 559.04 559.12 559.17 559.17 

10072431 575.06 573.95 573.28 573.28 

10072432 594.55 591.82 590.18 590.17 

10072433 617.20 612.37 609.49 609.46 

10072434 642.66 635.24 630.83 630.79 

10072435 670.66 660.11 653.89 653.83 

10072436 700.80 686.60 678.27 678.19 

10072437 732.14 713.83 703.16 703.07 

10072438 763.72 740.88 727.66 727.55 

10072439 802.87 773.85 757.23 757.10 

10072440 842.36 806.87 786.46 786.31 

10072441 840.02 804.29 783.81 783.66 

10072442 837.68 801.71 781.16 781.01 

10072501 007010000 10000 11 0.0975 2 

10072502 007030000 10000 1 1 0.0638 

10072503 007390000 10000 1 1 0.0725 40 

10072504 007410000 10000 1 1 0.062542 

10072601 0 0 0000 10.0975 2 

10072602 0 0 0000 10.06 38 

10072603 0 0 0000 1 0.0725 40 

10072604 0 0 0000 10.0625 42 

10072701 0 0.0 0.0 0.0 42 

10072801 0.0305 15.0 15.0 0.0 0.0 0.0 0.0 1.0 42 

0080000 outcore sngljun 

*0080101 007010000 009000000 0.0 0.5 0.5 0100100 

0080101 007010000 009000000 0.9-3 0.0 0.00000000 

0080110 8.0-3 0.0 1.0 1.0 

0080201 0 0.42336 0.42336 0.0 . ---------------------------------------

* Upper plenum 

0090000 upplenum pipe 

0090001 15 

0090101 6.65-3 15 

00903010.1 1, 0.112, 0.214, 0.20 13, 0.14 15 

0090601 90.0 15 

0090801 5.0-5 0.092 15 

0090901 0.0 0.0 14 

0091001000000 15 

0091101 0000000 14 

0091201 100.700859e+07 .M25840e+07 .327330e+07 

0091202 100.700857e+07 .125840e+07 .327280e+07 

0091203 100.700855e+07 .125840e+07 .327190e+07 

0091204 100.700851e+07 .125840e+07 .327090e+07 

0091205 100.

7

00847e+07 .1

2

5840e+07 .326990e+07 

0091206 100.700844e+07 .125840e+07 .326880e+07 

0091207 100.

7

00840e+07 .125840e+07 .326780e+07 

0091208 100.700837e+07 .125840e+07 .326660e+07

1.00000 0.0 1 

1.00000 0.0 2 

1.00000 0.0 3 

1.00000 0.0 4 

1.00000 0.0 5 

1.00000 0.0 6 

1.00000 0.0 7 

1.00000 0.0 

8

0091209 100.700833e+07 .125840e+07 .326540e+07 1.00000 0.0 9 

0091210 100.700830e+07 .125840e+07 .326

4 10e+07 1.00000 0.0 10 

0091211 100.700826e+07 .125840e+07 .326280e+07 1.00000 0.0 11 

0091212 100.7008

2

3e+07 .125840e+07 .326140e+07 1.00000 0.0 12 

0091213 100.700819e+07 .125840e+07 .325990e+07 1.00000 0.0 13 

0091214 100.

7

00816e+07 .125840e+07 .325890e+07 1.00000 0.0 14 

0091215 100.700814e+07 .125840e+07 .316290e+07 1.00000 0.0 15 

00913000 

0091301 5.72766e-02 5.72766e-02 0.0 01 

0091302 5.72542e-02 5.72542e-02 0.0 02 

0091303 5.72098e-02 5.72098e-02 0.0 03 

0091304 5.71637e-02 5.71637e-02 0.0 04 

0091305 5.71181e-02 5.71181e-02 0.0 05 

0091306 5.70705e-02 5.70705e-02 0.0 06 

0091307 5.70208e-02 5.70208e-02 0.0 07 

0091308 5.69690e-02 5.69690e-02 0.0 08 

0091309 5.69147e-02 5.69147e-02 0.0 09 

00913105.68580e-02 5.68580e-02 0.0 10 

0091311 5.67986e-02 5.67986e-02 0.0 11 

0091312 5.67365e-02 5.67365e-02 0.0 12 

0091313 5.66715e-02 5.66715e-02 0.0 13 

0091314 5.43874e-06 5.43874e-06 0.0 14 

0091401 0.092 0.0 1.0 1.0 14 

10092000 153200.046 

10092100 0 1 

10092101 10.050 1 0.054 

10092201 12 

10092301 0.02 

10092400 -1 

10092401 875.64 875.63 875.62 

10092402 875.32 875.31 875.30 

10092403 874.68 874.66 874.66 

10092404 874.00 873.98 873.98 

10092405 873.32 873.30 873,29 

10092406 872.60 872.58 872.57 

10092407 871.84 871.82 871.82 

10092408 871.05 871.03 871.02 

10092409 870.21 870.19 870.18 

10092410 869.33 869.31 869.30 

10092411868.41 868.39 868.38 

10092412 867.45 867.43 867.42 

10092413 866.44 866.42 866.41 

10092414 865.72 865.69 865.69 

10092415 821.03 821.03 821.03 "*10092401 821.5 3 

10092501 009010000 10000 I 10.1 1 

10092502 009020000 10000 10.11 2 

10092503 009030000 10000 1 0.21 4 

10092504 009050000 10000 11 0.2 13 

10092505 009140000 10000 1 10.14 15 

10092601 00000000 10.1 1 

10092602 00000000 10.112 

10092603 000 0 0000 1 021 4 

10092604 -1203011 10.2 13 

10092605 -1203011 10.14 15 

10092701 00.00.00.0 15 

10092801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 15 

0100000 coreout sngljun 

0100101009140003 011000000 0.0 0.0 0.0 0000000 

0100201 00.24771 0.24771 0.0 

*-----------------......................... 

* Hot Leg 

* -- 

-

--- ------------------------------.... 

0110000 hotleg pipe 

0110001 18 

0110101 1.52-3 18 

0110301 0.2 10, 0.15 17, 0.1052 18 

0110601 -2.0 10, -90.0 18 

01108015.0-5 0.044 18 

0110901 0.0 0.0 17 

0111001 000000 18 

0111101 000000017 

0111201 100.700816e+07 .125840e+07 .325810e+07 1.00000 0.0 1 

0111202 100.700816e+07 .125840e+07 .325720e+07 1.00000 0.0 2 

0111203 100.700816e+07 .125840e+07 .325630e+07 1.00000 0.0 3 

0111204 100.700817e+07 .125840e+07 .325540e+07 1.00000 0.0 4 

0111205 100.700817e+07 .125840e+07 .325450e+07 1.00000 0.0 5 

0111206 100.700817e+07 .125840e+07 .325350e+07 1.00000 0.0 6 

0111207 100.700817e+07 .125840e+07 .325260e+07 1.00000 0.0 7 

0111208 100.700817e+07 .125840e+07 .325160e+07 1.00000 0.0 8 

0111209 100.700817e+07 .125840e+07 .325060e+07 1.00000 0.0 9 

0111210 100.700817e+07 .125840e+07 .324960e+07 1-00000 0.0 10

E-4

I,
0111211 100.700819e+07 .125840e+07 .324880e+07 1.00000 0.011 

0111212 100.700822e+07 .125840e+07 .324800e407 1.00000 0.012 

0111213 100.700824e+07 .125840e+07 .324720e+07 1.00000 0.013 

0111214 100.700827e+07 .125840e+07 .324640e+07 1.00000 0.014 

0111215 100.700830e+07 .125840e+07 .324560e+07 1.00000 0.015 

0111216 100.700832e+07 .125840e+07 .324480e+07 1.00000 0.016 

0111217 100.700835e+07 .125840e+07 .324400e+07 1.00000 0.0 17 

0111218 100.700837e+07 .125840e+07 .324340e+07 1.00000 0.018 

01113000 

0111301 0.24755 0.24755 0.0 01 

0111302 0.247400.247400.0 02 

0111303 0.24723 0.24723 0.0 03 

0111304 0.24707 0.24707 0.0 04 

0111305 0.24690 0.24690 0.0 05 

0111306 0.24672 0.24672 0.0 06 

0111307 0.246540.246540.0 07 

0111308 0.24636 0.24636 0.0 08 

0111309 0.24617 0.24617 0.0 09 

0111310 0.24597 0.24597 0.0 10 

0111311 0.24583 0.24583 0.0 11 

0111312 0.24568 0.24568 0.0 12 

0111313 0.24553 0.24553 0.0 13 

0111314 0.24538 0.24538 0.0 14 

0111315 0.24522 0.24522 0.0 15 

0111316 0.24507 0.24507 0.0 16 

0111317 0.24491 0.24491 0.0 17 

0111401 0.044 0.0 1.0 1.0 17 

10112000 183200.022 

10112100 0 1 

10112101 10.026 10.030 

10112201 12 

10112301 0.02 

10112400 -1 

10112401 865.81 865.78 865.77 

10112402 865.21 865.18 865.17 

10112403 864.59 864.56 864.55 

10112404 863.96 863.93 863.92 

10112405 863.33 863.29 863.28 

10112406 862.68 862.65 862.64 

10112407 862.03 861.99 861.98 

10112408 861.36 861.33 861.32 

10112409 860.69 860.65 860.64 

10112410 860.01 859.97 859.96 

10112411859.61 859.57 859.56 

10112412 859.11 859.07 859.06 

10112413 858.60 858.56 858.55 

10112414 858.09 858.05 858.04 

10112415 857.57 857.53 857.52 

10112416 857.05 857.01 857.00 

10112417 856.53 856.49 856.48 

10112418 856.16 856.12 856.11 

*10112401 821.53 

10112501 011010000 10000 1 10.2 10 

10112502 011110000 10000 1 10.15 17 

10112503 011180000 10000 1 10.1052 18 

10112601 -1203011 10.2 10 

10112602 -1203011 10.15 17 

10112603 -1203011 10.1052 18 

10112701 0 0.0 0.0 0.0 18 

10112801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 18 

0120000 oucore sngljun 

0120101011010000 014000000 0.0 0.0 0.0 0000000 

0120201 00.25912 0.24480 0.0 

* Steam Condenser and Water Cooler 

0140000 heatexch pipe 

0140001 20 

0140101 7.20-3 6 9.8-3 14 7.20-3 20 

0140301 0.14 20 

0140601 -90.0 20 

0140801 5.0-5 16.0-3 5 

0140802 5.0-5 50.0-3 15 

0140803 5.0-5 16.0-3 20 

01409010.0 0.0 19 

0141001000000 20 

01411010000000 19 

0141201 100.700840e+07 .124750e+07 .288240e+07 .995200 0.0 1 

0141202 100.700844e+07 .124780e+07 .271920e+07 .991480 0.0 2 

0141203 100.700848e+07 .124870e+07 .263110e+07 .990140 0.0 3 

0141204 100.700853e+07 .125000e+07 .259420e+07 .987840 0.0 4

0141205 100.700858e+07 .125100e+07 .258190e+07 .989200 0.0 5 

0141206 100.700863e+07 .125130e+07 .258180e+07 .991680 0.0 6 

0141207 100.700868e+07 .125830e+07 .258180e+07 .997770 0.0 7 

0141208 100.700873e+07 .125840e+07 .258180e+07 .999850 0.0 8 

0141209 100.700878e+07 .125840e+07 .258180e+07 .998060 0.0 9 

0141210 100.700926e+07 .125840e+07 .258180e+07 .116080 0.010 

0141211 103.701022e+07 559.012 0.0 0.0 0.0 11 

0141212 103. 7011 24 e+0 7 559.012 0.0 0.0 0.0 12 

0141213 103.701225e+07 559.019 0.0 0.0 0.0 13 

0141214 103.701327e+07 559.029 0.0 0.0 0.0 14 

0141215 103.701443e+07 386.947 0.0 0.0 0.0 15 

0141216 103.701575e+07 356.921 0.0 0.0 0.0 16 

0141217 103.701709e+07 350.620 0.0 0.0 0.0 17 

0141218 103.701843e+07 348.948 0.0 0.0 0.0 18 

0141219 103.701977e+07 348.417 0.0 0.0 0.0 19 

0141220 103.70211 le+07 348.224 0.0 0.0 0.0 20 

01413000 

0141301 3.65580e-02 3.27312e-02 0.0 01 

01413024.98510e-02 2.09881e-02 0.0 02 

0141303 6.85847e-02 1.31201e-02 0.0 03 

0141304 7.64202e-02 7.48590e-03 0.0 04 

0141305 0.11440 3.07829e-03 0.0 05 

0141306 7.18394e-02 8.08266e-04 0.0 06 

0141307 5.81765e-02 8.43391e-04 0.0 07 

0141308 0.70891 8.48019e-04 0.0 08 

0141309 0.33806 2.49391e-04 0.0 09 

0141310 1.06252e-03 -0.40777 0.0 10 

0141311 9.39059e-04 8.06602e-04 0.0 11 

0141312 9.38895e-04 6.78740e-04 0.0 12 

0141313 9.38735e-04 7.01262e-04 0.0 13 

0141314 1.27751e-03 1.17414e-03 0.0 14 

0141315 9.93676e-04 9.93676e-04 0.0 15 

0141316 9.71927e-04 9.71927e-04 0.0 16 

0141317 9.67956e-04 9.67956e-04 0.0 17 

0141318 9.66902e-04 9.66902e-04 0.0 18 

0141319 9.66536e-04 9.66536e-04 0.0 19 

0141401 16.0-3 0.0 1.0 1.0 6 

0141402 50.0-3 0.0 1.0 1.0 13 

0141403 16.0-3 0.0 1.0 1.0 19 

10143000 203200.075 

10143100 0 1 

10143101 10.083 10.09 

10143201 1 2 

10143301 0.02 

10143400 -1 

10143401 665.54 665.49 665.48 

10143402 558.88 558.88 558.88 

10143403 558.87 558.87 558.87 

10143404 558.88 558.88 558.88 

10143405 558.90 558.89 558.89 

10143406 558.87 558.86 558.86 

10143407 559.02 559.02 559.02 

10143408 559.02 559.02 559.02 

10143409 559.06 559.06 559.06 

10143410 559.01 559.01 559.01 

10143411 559.01 559.01 559.01 

10143412 559.02 559.02 559.02 

10143413 559.03 559.03 559.03 

10143414 559.04 559.04 559.04 

10143415 386.97 386.97 386.97 

10143416 356.93 356.93 356.93 

10143417 350.63 350.63 350.63 

10143418 348.95 348.95 348.95 

10143419 348.42 348.42 348.42 

10143420 348.23 348.23 348.23 

*10143401 590.03 

10143501 014010000 10000 11 0.14 20 

10143601 -12 0 3011 10.14 20 

10143701 0 0.0 0.0 0.0 20 

10143801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 20 

0150000 oulheat sngljun 

0150101 014010000 016000000 0.0 0.0 0.0 0000000 

0150201 0 8.86352e-02 8.86352e-02 0.0 

* Lower Water Pipe 

0160000 lowpipe pipe 

0160001 18 

0160101 7.85-5 18 

0160201 7.85-5 112.4-6 127.85-5 17 

01603010.15 1, 0.2 6 0.222 7, 0.11 18 

0160601-90.0 7,0.0 18

E-5
0160801 5.0-5 0.01 18 

0160901 0.0 0.0 17 

0161001 000000 18 0161101 0000000 11 

0161102 0000100 12 

0161103 0000000 17 

0161201 103.702250e+07 348.2240.0 0.0 0.0 1 

0161202 103.

7 02417e+07 348.224 0.0 0.0 0.0 2 

0161203 103 

.

7 02609e+07 348.225 0.0 0.0 0.0 3 

0161204 103 .702800e+07 348.225 0.0 0.0 0.0 4 

0161205 103 .702992e+07 348.225 0.0 0.0 0.0 5 

0161206 103 .703183e+07 348.226 0.0 0.0 0.0 6 

0161207 103 .703385e+07 348.226 0.0 0.0 0.0 7 

0161208 103 .703492e+07 348.226 0.0 0.0 0.0 8 

0161209 103 .70

3

492e+07 348.226 0.0 0.0 0.0 9 

0161210 103 .703491e+07 348.226 0.0.0 0.0 10 

0161211 103 .70349 1e+07 348.226 0.0 0.0 0.0 11 

0161212 103 .703491e+07 348.227 0.0.0 0.0 12 

0161213 103.702459e+07 348.226 0.0 0.0 0.0 13 

0161214 103 .702458e+07 348.226 0.0 0.0 0.0 14 

0161215 103 .702458e+07 348.226 0.0 0.0 0.0 15 

0161216 103 

.

7

0

2

458e+07 348.227 0.0 0.0 0.0 16 

0161217 103 

.

7

02458e+07 348.227 0.0 0.0 0.0 17 

0161218 103 .702458e+07 348.227 0.0 0.0 0.0 18 

01613000 

01

6

1301 8.86351e-02 8.86351e-02 0.0 01 

0161302 8.86350e-02 8.86350e-02 0.0 02 

0161303 8.86349e-02 8.86349e-02 0.0 03 

0161304 8.86348e-02 8.86348e-02 0.0 04 

0161305 8.86346e-02 8.86346e-02 0.0 05 

0161306 8.86345e-02 8.86345e-02 0.0 06 

0161307 8.86344e-02 8.86344e-02 0.0 07 

0161308 8.86343e-02 8.86343e-02 0.0 08 

0161309 8.86343e-02 8.86343e-02 0.0 09 

0161310 8.86343e-02 8.86343e-02 0.0 10 

0161311 8.86342e-02 8.86342e-02 0.0 11 

0161312 8.86342e-02 8.86342e-020.0 12 

0161313 8.86346e-02 8.86346e-020.0 13 

0161314 8.86346e-02 8.86346e-02 0.0 14 

0161315 8.86346e-02 8.86346e-02 0.0 15 

0161316 8.86345e-02 8.86345e-02 0.0 16 

0161317 8.86345e-02 8.86345e-02 0.0 17 

01614010.0100.0 1.0 1.0 11 

01614020.00175 0.0 1.0 1.0 12 

0161403 0.010 0.0 1.0 1.0 17 

10162000 183200.005 

10162100 0 1 

10162101 10.010 10-016 

10162201 1 2 

10162301 0.02 

10162400 -1 

10162401348.22 348.22 348.22 

10162402 348.23 348.23 348.23 

10162403 348.23 348.23 348.23 

10162404 348.23 348.23 348.23 

10162405 348.23 348.23 348.23 

10162406 348.23 348.23 348.23 

10162407 348.23 348.23 348.23 

10162408 348.23 348.23 348.23 

10162409 348.23 348.23 348.23 

10162410 348.23 348.23 348.23 

10162411 348.23 348.23 348.23 

10162412 348.23 348.23 348.23 

10162413 348.23 348.23 348.23 

10162414 348.23 348.23 348.23 

10162415 348.23 348.23 348.23 

10162416 348.23 348.23 348.23 

10162417 348.23 348.23 348.23 

10162418 348.23 348.23 348.23 

*10162401 325.03 

10162501 016010000 10000 11 0.150 1 

10162502 016020000 10000 1 1 0.2006 

10162503 016070000 10000 1 10.2227 

10162504 016080000 10000 1 10.11 18 

10162601 000 10.150 1 

10162602 00010.200 6 

10162603 00010.222 7 

10162604 00010,11 18 

10162701 00.00.00.0 18 

10162801 0.0 15.0 15.0 0.0 0.0 0.0 0.0 1.0 18 

0170000 inlow sngljun 

0170101 016010000 0050200010.0 0.0 0.0 000o00 

0170201 0 8.86345e-02 8.86345e-02 0.0

* SECOND CIRCUIT 

2010000 tdv201 tmdpvol 

2010101 0.0 2.0 2.0 0.0 0.0 0.0 1.0-6 0.0 0 

2010200 103 

2010201 0.0 10.5+6 550.2 

2020000 regul tmdpjun 

2020101 201000000 203000000 0.0 

2020200 1 

2020201 0.0 0.50 0.0 0.0 

2030000 htexch pipe * heat exchanger 

2030001 6 

2030101 1.327-4 6 

2030301 0.14 6 

2030601 90.0 6 

2030801 2.0-6 0.0136 6 

2030901 0.0 0.0 5 

*crdno tlpvbfe 

2031001 0000000 6 

*crdno efvcahs 

203110100010005 

2031201 103 .100139e+08 551.936 0.0 0.0 0.0 1 

2031202 103.100113e+08 553.273 0.0 0.0 0.0 2 

2031203 103 .100088e+08 554.287 0.0 0.0 0,0 3 

2031204 103 .100063e+08 555.083 0.0 0.0 0.0 4 

2031205 103.100038e+08 555.723 0.0 0.0 0.0 5 

2031206 103 .100013e+08 556.191 0.0 0.0 0.0 6 

20313000 

*2031301 0.0 0.0 0.0 5 

2031301 4.9667 4.9667 0.0 1 

2031302 4.9829 4.9829 0.0 2 

2031303 4.9954 4.9954 0.0 3 

2031304 5.0054 5.0054 0.0 4 

2031305 5.0135 5.0135 0.0 5 

2040000 sj204 sngljun 

2040101 203010000 205000000 0.0 0.0 0-0 001100 

2040201 0 5.0195 5.0195 0.0 

2050000 tdv2O5 tmdpvol 

2050101 0.0 2.0 2.0 0.0 0.0 0.0 1.0-6 0.0 0 

2050200 103 

2050201 0.0 10.0+6 550.1 

12031000 62200.0068 

12031100 01 

12031101 10.008 

12031201 1 1 

12031301 0. 1 

12031400 -1 

12031401 553.60 556.94 

12031402 554.45 556.81 

12031403 555.18 556.97 

12031404 555.78 557.19 

12031405 556.28 557.41 

12031406 556.60 557.42 

*12031401 550.1 2 

12031501 203010000 100001 12.06 

12031601 014010000 10000110 12.06 

12031701 00.000 0.06 

12031801 0.0 20.0 20.0 0.0 0.0 0.0 0.0 1.0 6 

12031901 0.0 20.0 20.0 0.0 0.0 0.0 0.0 1.0 6 

2110000 tdv21I tmdpvol 

2110101 0.0 2.0 2.0 0.0 0.0 0.0 1.0-6 0.0 0 

2110200 103 

2110201 0.0 8.5+6 345.0 

2120000 regul tmdpjun 

2120101 211000000 213000000 0-0 

2120200 1 

21202010.0 0.50 0.0 0.0 

2130000 httexch pipe * heat exchanger 

21300016 

2130101 1.327-46 

21303010.14 6 

2130601 90.0 6 

21308012.0-6 0.0136 6 

E-6

I,

I
2130901 0.0 0.05 

*crdno tlpvbfe 

21310010000000 6 

*crdno efvcahs 

21311010001000 5 

2131201 103.801473e+07 347.537 0.0 0.0 0.0 1 

2131202 103.801204e+07 347.948 0.0 0.0 0.0 2 

2131203 103.800937e+07 348.035 0.0 0.0 0.0 3 

2131204 103 .800670e+07 348.058 0.0 0.0 0.0 4 

2131205 103 .800402e+07 348.065 0.0 0.0 0.0 5 

2131206 103 .800135e+07 348.068 0.0 0.0 0.0 6 

21313000 

*2031301 0.0 0.0 0.0 5 

2131301 3.8501 3.8501 0.0 1 

2131302 3.8511 3.85110.02 

2131303 3.8513 3.85130.03 

2131304 3.8513 3.8513 0.04 

2131305 3.8513 3.8513 0.05 

2140000 sj204 sngljun 

2140101 213010000 215000000 0.0 0.0 0.0 001100 

21402010 3.8514 3.8514 0.0 

2150000 tdv205 tmdpvol 

2150101 0.0 2.0 2.0 0.0 0.0 0.0 1.0-6 0.0 0 

2150200 103 

2150201 0.0 8.0+6 345.0 

12131000 62200.0068 

12131100 01 

12131101 10.008 

12131201 1 1 

12131301 0. 1 

12131400 -1 

12131401 350.63 355.07 

12131402 348.44 349.16 

12131403 348.14 348.29 

12131404 348.09 348.12 

12131405 348.07 348.09 

12131406 348.07 348.08 

12131501 213010000 10000 1 1 2.0 6 

12131601 014150000 10000 110 12.06 

12131701 00.00.0 0.06 

12131801 0.0 20.0 20.0 0.0 0.0 0.0 0.0 1.0 6 

12131901 0.0 20.0 20.0 0.0 0.0 0.0 0.0 1.0 6 * -.....---......--- --.--............. 

"*general tables 

*s-steel 

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 900.025. 

20100108 1000.0 26. 

20100109 1100.0 28. 

20100110 1200.0 29. 

20100111 1400.029. 

20100151 295.0 3.686+6 

20100152 400.03.686+6 

20100153 500.03.801+6 

20100154 600.03.874+6 

20100155 700.0 3.955+6 

20100156 800.0 3.991+6 

20100157 900.04.039+6 

20100158 1000.0 4.043+6 

20100159 1100.04.113+6 

20100160 1200.0 4.115+6 

20100161 1400.04.115+6 *talkohlorit 

20100200 tbl/fctn 1 1 

20100201 295.0 1.5 

20100202 400.0 1.2 

20100203 500.0 1.1 

20100204 600.0 1.0 

20100205 700.00.9 

20100206 800.00.8 

20100207 900.00.75 

20100208 1400.0 0.75 

20100251 295.02.128+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 

20100256 800.0 3.080+6 

20100257 900.0 3.220+6 

20100258 1400.0 3.220+6 

20100300 tbllfctn 11 

20100301 2.5 

20100351 4.55+6 

**heat source 

20200100 power 0 1. 1000. 

*20200101 0.00 0.0 

*20200102 10.00 0.00 

*20200103 20.00 22.97 

20200103 00.00 22.97 **heat 

20200200 temp 0 

20200201 0.00 547.0 **heat 

20200300 temp 0 

20200301 0.00 325.0 

20200400 temp 0 

20200401 0.00430.0 

20200500 temp 0 

20200501 0.00520.0 

20201100 htc-t 0 

20201101 0.000.0 

20201200 temp 0 

20201201 0.00295.0 

.*end of data set

E-7
NRC FORM 335 U.S. NUCLEAR REGULATORY COMMISSION 1. REPORT NUMBER 

(2-89) (Assigned by NRC, Add Vol., Supp., Rev., 

NRCM 1102, and Addendum Numbers, If any.) 

3201, 3202 BIBLIOGRAPHIC DATA SHEET 

(See instructions on the reverse) 

2. TITLE AND SUBTITLE N UREG/IA-0208 

Analyses of the VTI Test Data on the Behavior of the Heated Rod Temperatures in the Partially 

Uncovered VVER-440 Core Model Using RELAP5/MOD3.2.2 GAMMA 3. DATE REPORT PUBLISHED 

MONTH YEAR 

April 2002 

4. FIN OR GRANT NUMBER 

5. AUTHOR(S) 6. TYPE OF REPORT 

V.A.Vinogradov, A.Y.Balykin technical 

7. PERIOD COVERED (inclusive Dates) 

8. PERFORMING ORGANIZATION - NAME AND ADDRESS (it NRC, provide Division, Office or Region, U.S. Nuclear Regulatory Commission, and mailing address; it contractor, 

provide name and mailing address.) 

Russian Research Center "Kurchatov Institute" 

Kurchatov Square 1 

123182, Moscow Russia

9. SPONSORING ORGANIZATION - NAME AND ADDRESS (If NRC, type 'Same as above", if contractor, provide NIRC 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

This is a Russian CAMP in-kind contribution 

11. ABSTRACT (200 words or less) 

This report has been prepared as a part of the Agreement on Research Participat ion and Technical Exchange under the 

International Code Application and Maintenance Program. 

VTI test data on the behavior of the heated rod temperatures in the partially u ncovered VVER -440 core model were simulated 

with RELAP5/MOD3.2.2GAMMA to assess the code, especially its heat transfer mode Is for modeling phenomena in the 

partially uncovered core under Small Break LOCA conditions. This problem addresses the phenomena of high importance to 

VVER-440 safety. 

Series of the experiments have been carried out in the VVER-440 loop model at t he VTI Test Facility which are directly related 

to this issue. Two tests conducted in the stationary conditions with the transition mode of a steam flow in the core channel were 

chosen for the assessment calculations with the code. 

Experimental VVER-440 loop model includes the models of all the main elements o f a reactor, loop's hot leg model and cold 

leg simulator, and also a steam generator simulator with an active heat removal. The fuel assembly model consists of 19 

electrically heated rod simulators of 9.1 mm outer diameter and 2.5 m heated he ight. The rod simulators are composed in the 

rod bundle in a hexagonal array with a pitch equal 12.2 mm (P/D=1.34). 

First a study of the effect of the hydraulic nodalization to the code results w as performed using different number of hydraulic 

volumes for the core model. After the choice of proper nodalization and maximum user-specified time step, the base case 

calculations were done for the tests. The differences between the code predicti ons for the behavior of rod's wall temperatures 

and test data are described and analyzed. 

Sensitivity studies were carried out to investigate the influence of an increas e in the calculated coefficients of heat transfer 

from the heated rods to a steam flow on the axial distribution of rod's wall temperatures in the uncovered part of core model.

12. KEY WORDS/DESCRIPTORS (ust words or phrases that will assist researchers in locating Me report.) 13. AVAILABIUTY STATEMENT 

Sunlimited 

partially uncovered core, RELAP5, VVER-440 

14. SECURITY CLASSIFICATION 

(This Page) 

unclassified 

ffhis Report) 

unclassified 

15. NUMBER OF PAGES 

16. PRICE

NRC FORM 335 (2-89) This form was electronically produced by Elite Federal Forms, Inc.
1 14

Printed 

on recycled', 

Federal Recycling Program
NUREG/IA-0208 ANALYSIS OF THE VTI TEST DATA ON THE BEHAVIOR OF THE HEATED ROD 

TEMPERATURES IN THE PARTIALLY UNCOVERED VVER-440 CORE MODEL USING 

RELAP5/MOD3.2.2 GAMMA 

UNITED STATES 

NUCLEAR REGULATORY COMMISSION 

WASHINGTON, DC 20555-0001

OFFICIAL BUSINESS 

PENALTY FOR PRIVATE USE, $300

JULY 2002