NUREG/IA-O 112

ECN-C-92-008

International

Agreement Report

Assessment of RELAP5/MOD2

Against ECN-Reflood Experiments

Prepared by

A. Woudstra, J. P. A. Van De Bogaard, P. M. Stoop

Netherlands Energy Research Foundation ECN

Service Unit General Services

P. 0. Box 1, NL-1755 ZG Petten

The Netherlands

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

Washington, DC 20555-0001

July 1993

Prepared as part of

The Agreement on Research Participation and Technical Exchange

under the International Thermal-Hydraulic Code Assessment

and Application Program (ICAP)

Published by

U.S. Nuclear Regulatory Commission
NOTICE

This report was prepared under an international cooperative

agreement for the exchange of technical information. Neither

the United States Government nor any agency thereof, or any of

their employees, makes any warranty, expressed or implied, or

assumes any legal liability or responsibility for any third party's

use, or the results of such use, of any information, apparatus product or process disclosed in this report, or represents that its use

by such third party would not infringe privately owned rights.

Available from

Superintendent of Documents

U.S. Government Printing Office

P.O. Box 37082

Washington, D.C. 20013-7082

and

National Technical Information Service

Springfield, VA 22161
NUREG/IA-O112

ECN-C-92-008

International

Agreement Report

Assessment of RBLAP5/MOD2

Against ECN-Reflood Experiments

Prepared by

A. Woudstra, J. P. A. Van De Bogaard, P. M. Stoop

Netherlands Energy Research Foundation ECN

Service Unit General Services

P. 0. Box 1, NL,1755 ZG Petten

The Netherlands

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

Washington, DC 20555-0001

July 1993

Prepared as part of

The Agreenient~on Research Participation and Technical Exchange

under the International Thermal-Hydraulic Code Assessment

and Application Program (ICAP)

Published by

U.S. Nuclear Regulatory Commission

NOTICE

This report is based on work performed under the sponsorship of the

Netherlands Ministry for Social Affairs and Employment. The information in

this report has been provided to the USNRC under the terms of an information

exchange agreement between the United States and The Netherlands (Technical

Exchange and Cooperation Agreement between the United States Nuclear

Regulatory Commission and the Netherlands Energy Research Foundation ECN).

The Netherlands has consented to the publication of this report as a USNRC

document in order that it may receive the widest possible circulation among

the reactor safety community. Neither the United States Government nor The

Netherlands or any agency thereof, or any of their employees, makes any

warranty, expressed or implied, or assumes any legal liability of

responsibility for any third party's use, of the results of such use, or any information, apparatus, product or process disclosed in this report or

represents that its use by such third party would not infringe privately owned

rights.
-2 -

ABSTRACT

As part of' the ICAP (International Code Assessment and Applications Program) agreement between EON (Netherlands Energy Research Foundation) and

USNRC, ECN has performed a number of' assessment calculations with the computer program RELAP5.

This report describes the results as obtained by EON from the assessment

of the thermohydraulic computer program RELAP5/MOD2/CY 36.05 versus a

series of reflood experiments in a bundle geometry. A total number of

seven selected experiments have been analyzed, from the reflood experimental program as previously conducted by EON under contract of the Commission of the European Communities (CEO). In this document, the results

of the analyses are presented and a comparison with the experimental data

is provided.
-3 -

EXECUTIVE SUMMARY

For both Pressurized and Boiling Water Reactors (PWR's and BWR's) the bottom ref'looding process following a large break LOCA is one of' the phenomena of' great interest to be examined. To test the ability of RELAP5/MOD2 to

model such conditions a great number of experimental programs has been

conducted to study the reflood heat transfer process and quench front propagation for bottom flooding conditions. The assessment calculations as

reported in this document concern reflood experiments as conducted by the

Netherlands Energy Research Foundation (EON). The experimental facility

represents a 36-rod bundle segment of a standard 15 x 15 PWR fuel design

with an axially uniform power profile.

This report describes comparisons between RELAP5/MOD2 calculations and

measurements of wall temperatures at different levels, quench front

position, collapsed liquid level, mass inventory in the bundle and integrated boundary mass flows.

The prime conclusions are as follows:

- The RELAP5/MOD2 reflood heat transfer model is only valid for high

reflood rates.

- Liquid carry-over is strongly overpredicted.

- Refinement of' axial nodalization above the recommended value did not

improve the calculational results.

CONTENTS PAGE

ABSTRACT 2

EXECUTIVE SUMMARY 3

1. INTRODUCTION 7

2. FACILITY AND TEST DESCRIPTION 10

2.1. Geometrical layout 10

2.2. Instrumentation 10

2.3. Operational procedures 11

2.4. Test matrix 12

2.5. Selected experiments 12

3. CODE INPUT MODEL DESCRIPTION 21

3.1. Input model sensitivity analyses 21

3.2. Base case input model 22

3.3. Initial and operating conditions 22

4. RESULTS 27

4.1. Sensitivity analyses 27

4.2. RELAP5/MOD2 results vs. experimental data 27

4.3. Analysis of results 28

4.4. Suggestions for model improvements 29

4.5. User guidelines 29

5. RUN STATISTICS 69

6. CONCLUSIONS 70

REFERENCES 71

LIST OF TABLES 72

LIST OF FIGURES 73

APPENDIX A: RELAP5/MOD2 INPUT DECK 76

-7 -

1. INTRODUCTION

As part of the International Code Assessment and Applications Program

(ICAP) agreement between the Netherlands Energy Research Foundation (EON)

and the United States Nuclear Regulatory Commission (US-NRC), EON has conducted a number of assessment calculations using the thermohydraulic

system code RELAP5/MOD2/CY 36.05. ref. [1). The assessment calculations as

reported in this document concern a selection of seven reflood experiments

as conducted by EON under contract of the Commission of the European Communities (CEO). The results of this ECN-reflood experimental program have

been documented in ref. [2).

As described in NUREG-1271, ref. [5), quantification of code uncertainty

for Large Break Loss-of-Coolant Accidents (LB-LOCA), Small Break

Loss-of-Coolant Accidents (SB-LOCA) and operational transients requires a

large number of assessment calculations to be performed for a variety of

integral as well as separate effect experiments. For each of these three

classes of accidents, phenomenologically based code assessment matrices

have been composed for both the Pressurized and Boiling Water Reactors

environment (PWR's and BWR's). One of the phenomena to be examined concerns the reflooding process following LB-LOCA in both PWR's and BWR's.

A number of separate effect experimental programs have been conducted to

study the reflood heat transfer process and quench front propagation for

bottom flooding conditions. Table 1.1 lists some of these experimental

programs including their main characteristics. As can be observed from

this table, the EON-reflood experimental facility represents a 36-rod

bundle segment of a standard 15 x 15 PWR fuel design. The ECN-reflood

experimental program differs from other reflood experimental programs

by the axially uniform power profile being used.

RELAP5/MOD2 reflood assessment results already available indicate that

discrepancies exist between code predictions and experimental results,

ref. [3). Liquid carry-over is grossly overpredicted and therewith underprediction of the collapsed liquid level occurs. Most of this RELAP5/MOD2

assessment work indicates the cause of overprediction of carry-over is an

overestimation of the interphase drag in rod bundle goers, particu-
-8 -

larly in the slug flow regime. As stated in ref. [3], most of the

RELAP5/MOD2 interphase drag model assessment during..the development stage

has been based mainly on tube and open vessel data, and only to a minor

extent on rod bundle data.

The ECN-reflood data base comprises a total of 48 experiments. Out of this

data base, a total of seven experiments have been selected for code

assessment, based on the different physical phenomena observed during the

experiments and the parameter variations used.

The structure and contents of this assessment document is as much as possible in conformity with the guidelines described in NTJREG-1271, ref. [5].

Chapter 2 presents a description of the ECN-reflood experimental facility,

the operating procedures and the test matrix. In chapter 3 the RELAP5/MOD2

input model is being described, as well as the initial and operating conditions of the selected experiments. The results of' the RELAP5/MOD2 analyses are presented in chapter 14 and compared against the experimental data.

Sensitivity analyses with respect to e.g. nodalization are also given in

chapter [4]. Information with respect to run statistics can be found in

chapter 5, followed by the conclusions in chapter 6. Finally, the

F{ELAP5/MOD2 input deck being used for one of the experiments is being

shown in Appendix A.
- 9-

Table 1.1. Comparison of some reflood experimental facilities.

No. f ros Heght Axial power Remark No. ods of Heiht (%) profile _______

Flecht 7 x 7 & 10 x 10 100 Cosine, 15 x 15

Skewed

Flecht 21, 161, 163 10Cosine, 17 x~ 17

seaset Skewed

Neptun 6 x 6 50 Cosine BWR geometry

TITF 8 x8 100 Flat PWR 17 x17

rod geometry

ECN-reflood 6 x 6 100 Uniform PWR 15 x 15

_________ _____________ _________________ 1 rod geometry
- 10 -

2. FACILITY AND TEST DESCRIPTION

An extensive description of the ECN 36-rod reflood experimental program

can be found in ref. [2). Here, only a brief description of the facility

and the experimental program will be given.

2.1. Geometrical layout

A schematic picture of the ECN 36-rod reflood test facility is shown in

Fig. 2.1. Apart from the test section, the facility consists of the following components:

- A pressurized water supply accumulator and injection line;

- Two carry-over tanks connected to the test section upper plenum;

- A blowdown tank for steam condensation.

Heat tracing of piping and vessels has been utilized to prevent steam condensation effects.

The test section itself comprises a 36-rod bundle, located inside a rectangular low mass housing. The bundle consists of 32 electrically heated

rods and 4 unheated corner rods, which are used to bear instrumentation,

instrumentation leads and the grids. The indirectly heated rods (heated

length 3.00 m, outer diameter 10.7 mm) are divided into three concentric

rows. Axially a uniform power profile is applied, while radially the 4

centre rods, the inner row and the outer row heater rods can be set at

different power levels to establish a radially non-uniform power or

initial wall temperature profile. The upper plenum of the test section

contains a mechanical steam water separator, see Fig. 2.2.

2.2. Instrumentation

The EON 36-rod reflood test facility has been instrumented using:

- thermocouples for temperature measurements;

- flowmeters for steam and water flow measurements;

- pressure transducers for absolute pressures, pressure differences

and water level measurements;

- resistors for heater current measurements.
- 11

The overall test facility instrumentation is shown in Fig. 2.1. Instrumentation directly coupled to the test section is shown in Figs. 2.3

and 2.4. As indicated, housing differential pressure cells are located

every 0.25 m to obtain void fraction measurements along the heated length

of the bundle. Channel thermocouples are mounted to measure the coolant

temperature radially and axially across the bundle. Apart from this, wall

thermocouples are positioned at 8 levels per rod at different azimuthal

positions, as shown in Fig. 2.4.

2.3. Operational procedures

In order to meet the initial conditions for each experiment, first the

accumulator is filled with water and heated to the desired coolant

temperature. Next, the test section, the carry-over vessels and steam/

water separator vessel are pressurized by nitrogen at the desired

pressure. The accumulator is pressurized with nitrogen up to a pressure

level which is necessary for the required flow rate control.

In case of radially uniform initial temperature profiles, the bundle was

initially low powered. For radially non-uniform high temperature profiles,

a radially non-uniform power profile was initially supplied to the bundle.

Once the initial pressure and temperature conditions are met, the desired

coolant flow is established. At the time when the coolant reached the bottom side of the test section heated length the power is (stepwise) increased to the desired level. This moment is determined by a fast temperature increase of the heater rod thermocouple at level 1, see Fig. 2.3.

This time, which could also be determined by a pressure increase of the

lowest differential pressure cell in the heated part of the test section

is defined as the "start of the experiment".

After all heater rods are quenched, as could be observed from the rod wall

thermocouple measurements, the heater power is switched off, and the experiment is terminated.
- 12 -

2.4. Test matrix

The test matrix of' the experimental program was designed to provide an

experimental data base in order to determine the reflood phenomena as

a function of' the next parameters:

- flooding rate;

- system pressure;

- subcooling;

- initial cladding temperature and radial temperature distribution;

- rod power level and radial power distribution.

The range of test conditions and parameters studied during the experimental program is shown in Table 2.1. The complete test matrix comprises 48 experiments and is shown in Table 2.2.

2.5. Selected experiments

Out of the test matrix as shown in Table 2.2, 7 experiments have been selected for purpose of code assessment. Those selected experiments are presented in Table 2.3. Selection of the experiments is based on both the

parameter variations being used for the various experiments, and the different physical phenomena being observed.

The data present in Tables 2.2 and 2.3 originates from ref. [2). However,

in order to perform tLhe code assessment work as accurate as possible, more

precise initial conditions have been obtained from the available data

tapes. These latter initial conditions have been summarized in Table 2.4.
- 13 -

Table 2.1. Range of' initial test conditions for the analyzed reflood

experiments

Initial heater rod wall temperature 200-C - 850-C

Power 1.7 - 5 W/cm2

Bundle outlet pressure

(upper plenum pressure) .2 - .6 MPa

Flooding rates:

Constant 1.4 - 8.0 cm/sec

Variable in steps 3.0 - 0.9 cm/sec

Coolant subcooling 20*C - 80*C
- 14

Table 2.2. Test matrix for the ECN-reflood program

Exp. Twall Power V i Tin

N.(P)initial, lev.4 (*C) (W/cm2) in/sc (

o. (P) c.r. Ii.r. Io.r. c.r. Ii.r. Io.r. (csc) (C

3215

3216

3218

3220

3221

3224

3229

3230

3231

4100

4102

4106

4113

4114

4115

4116

4117

4118

4119

4120

4121

4122

4124

4125

4126

4127

4128

4129

4130

4131

4132

4133

4134

4135

4136

4137

4138

4139

4140

4141

4142

4143

4144

4145

4146

4147

4149

4150

.6

.2

.6

.2

.2

.2

.4

200

200

600

400

600

400

600

600

600

600

600

600

600

800

800

800

800

800

200

200

600

400

600

400

600

60

600

600

600

600

600

800

800

800

800

800

800

800

800

200

200

600

400

600

400

600

600

600

600

600

600

800

800

8oo

800

800

800

3.3

3.4

3.3

1.7

4.0

3.4

4.1

3.4

3.4

3.3

3.3

3.6

3.8

3.8

3.8

3.8

3.7

3.6

3.6

3.6

3.6

1.9

3.6

0

3.6

0

5.2

4.8

3.6

3.6

0

0

3.6

3.6

5

5

3.6

0

3.6

0

3.6

0

3.6

0

3.6

3.6

3.6

3.6

3.6

3.7

3.6

1.8

2.2

3.7

2.9

3.7

3.7

3.6

3.6

3.6

3.6

3.0

2.2

3.0

2.2

3.6

3.6

3.6

3.6

1.7

2.2

3.6

2.2

3.6

5.0

5.0

2.1

2.2

3.6

3.6

2.2

2.1

5

5

3.6

3.6

3.6

3.6

3.6

3.6

3.6

3.6

3.6

3.6

3.6

3.6

3.6

3.6

3.6

1.8

1.8

3.6

2.2

3.6

3.6

3.5

3.5

3.5

3.5

2.2

1.4

2.1

1.4

3.5

3.5

3.6

3.5

1.7

1.4

3.5

1.4

3.5

4.8

4.8

1.3

1.4

3.5

3.5

1.4

1.3

5

5

3.6

3.6

3.6

3.6

3.6

3.6

3.6

3.6

3.6

3.6

3.6

3.6

1.5

.7

1.3

1.5

1.4

1.1-0.9

1.7-0.9

8.0

5.0

2.4

5.0

8.0

2.4

8

2.4

8

2.4

8

2.4

8

2.4

8

2.4

8

2.4

8

2.4

8

80

40

140

100

100

40

100

40

100

40

100

100

100

40

60

120

c.r. - central rods

i.r. - inner ring rods

o.r. - outer ring rods
- 15 -

Table 2.3. Selected experiments

Experi- Pres- Wall Power (W/cm') Inlet Inlet Sub

ment sure temp. velocity temp. cooling

(MPa) (K) c.r. i.r. o.r. (cm/s) (K) (K

3216 0.2 .473 3.4 3.7 3.6 1.5 313 80

3224 0.2 473 3.4 3.7 3.6 1.5 373 20

4100 0.2 873 3.3 3.6 3.5 8.0 373 20

4106 0.2 873 3.6 3.6 3.5 2.4 373 20

4120 0.2 873 3.6 3.6 3.6 8.0 313 80

4138 0.2 1073 3.6 3.6 3.6 2.4 373 20

14149 10.4 11073 13.6 3.6 13.6 1 2.4 1393 1 3

c.r. = central rods

i.r. = inner ring rods

o.r. = outer ring rods
Table 2.4. Initial and operating conditions

EXP P T t v Wall temperature (K) t Power Power inn in level 2 __ (MPa) (JKj () (M/S) 2_ 3 4F 5 6 7 8 (s) MW (W/cm)

3216- 0.2 313 0 00426.0

4. 0.1486 450 459 463 473 473 449 449 14 114805.3o .5

_____805.0 .014356 ___ _____ 587.5 115736.9 3.59

3224 0.2 373 0 0 0 475

5.0 0.014371 4716747 43 47 6 425: 113668.6 3.52 ___1192.5 .014193 __ __ 965.0 115347.2 3.57

41oo~ 0.2 373 0 0 0 8962.0

7.5 .0o 4 899 893 893 873 865 863 846 17.0 8962.0

7. 085920.5 114336.6 3.54

1 1_ 1000.0 .080549 __1_1 398.0 115819.2 3.59

4106 0.2 373 0 0 0 6505.0

7.4 o 6 6 6 6 7 7 5 6.0 6505.0

7.5 .023222 80 83 87 88 80 70 50 11.0 112308.7 3.48

1000.0_ .023222 ____781.0 114510.7 3.55

41200 0.2 313 0 0 0 6558.0

5.9 0 849 851 859 857 860 859 841 13.0 6558.0

6.0 .081754 16.0 113832.5 3.53 ____ 1000.0 o081754 1___ 1______ 131.5 115350.4 3.57

4138 0.2 373 0 0 0 18806.0

7.9 0 10 115 11 l8 12 12114.0 18806.0

8.0 .02349 10 115 11 118 12 121 1095 19.0 112584.2 3.49

1000.0 .02349 409.0 114032.4 3.53 ______1 1______ _ 799.0 114973.0 3.56

4149W 0.4 393 0 0 0 10390.0

5.9 0 102 18 14 11 15 11 03 10.0 10390.0

6.0 .023123 102 18 14 11 15 11 03 14.0 112502.3 3.49

200.0 .023267 574.0 114565.7 3.55

380.0 .023275 1 _ _ 1___ _ 1_ 766.0 1 .023273 1_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

C'
- 17

suI'?LY VESSEL

TfST S!ECTION STEAM FLOW tTASURfNTNT SL6OUI)'J TAX%

2-

(I r p r

F - Io... L *Le..3. F - Preooefe. T - T-.i.rat-ro

- -- - -- Trace heative

Figure 2.1. ECN-Reflood test facility schematics.
- 18 -

.. i

Figure 2.2. Test section and steam/water separator.
- 19 -

chati. teoperstures

PUISe-hesCad t.C.'S

in Cutler

3097

2375

h

2553 !2

I 3 210 w

500

1 2500

f b5000

b653

500

cress soction Svcs 47.8 c22 subeha

hydras.iic diasecer 22.5 em rod di

len* 1bydrauiie disamter 10.6 sw

s15aer 20 .7 a

Figure 2.3. Reflood instrumentation in 36-rod bundle.
- 20 -

Q Dire ction of flow,

9

NORTH

-7

9

Channel thermocouple in

certain locations of levels e. ( an~d -t

cross section area

hydraulic diameter

47.8 cm2

12.5 mm

subchannel hydraulic diameter 13.6 mm

rod diameter 10.7 mm

Figure 2.14. Cross-section of the bundle with thermocouple positions.
- 21 -

3. CODE INPUT MODEL DESCRIPTION

The nodalization of the EON 36-rod reflood test facility is quite simple.

As indicated in Fig. 3.1 the electrically heated rod bundle is modelled as

a pipe which is connected to a heat slab representing the heater rods.

Mass flow, pressure and temperature of water entering the lower plenum of

the test section are controlled by the time dependent junction 115 and the

time dependent volume 110. Downstream of the test section, the steam water

separator has been modelled with the RELAP5 separator component. The separator component is connected to the time dependent volumes 950 and 955.

3.1. Input model sensitivity analyses

Parameters for which a sensitivity analysis may be performed are the

length of the hydrodynamic nodes and the maximum number of fine mesh

intervals as applied by RELAP5/MOD2 to calculate the axial heat conduction in the rods when using the reflood model. User recommendations suggest a length of the hydrodynamic nodes between 0.15 and

0.61 m, and a maximum number of axial fine mesh intervals equal to 16

or 32. The maximum time step size should range between 0.01 and 0.05

seconds.

Four sensitivity analyses have been performed for experiment number 4100.

The parameter variations studied are listed in Table 3.1. while the corresponding nodalization schemes are presented in Fig. 3.1. The resulting

rod wall temperature time histories for levels 2 and 3 as identified in

Fig. 2.3. are shown in respectively Figs. 3.2 and 3.3. As can be observed

from these figures, run 1, 2, and 3 give approximately the same temperature behaviour. Run 4, in which volume lengths of 0.5 m have been used,

deviates significantly from the previous three runs, but nevertheless comes closest to the experimentally determined temperature-time histories.

However, for purpose of determination of code uncertainty the nodalization

of run 3 has been selected as the base case input model for code assessment. The temperature time histories as obtained for this run only differ

to a minor extend from the ones resulting from run 1 and 2.
- 22 -

Furthermore, a hydrodynamic node length equal to 0.25 m as used in run 3

seems to be the lower bound with respect to core modelling for an actual

nuclear power plant. RELAP5/MOD2 plant transient analyses using shorter

length of the core hydrodynamic nodes will end-up in unacceptably high

computer running times. The number of axial fine mesh intervals does not

appear to influence the calculated temperature time histories significantly. Since a two times greater number of mesh intervals results in a small

increase in computer running time, as will be shown in chapter 5, the finest mesh intervals will be used in the base case input model.

3.2. Base case input model

Based on the considerations as outlined in the previous section, the base

case RELAP5/MOD2 input model nodalization is shown in Fig. 3.4. The hydraulic volumes have a length of 0.25 m and the number of axial fine mesh

intervals equal to 32. The maximum time step size is fixed at 0.01 s.

3.3. Initial and operating conditions

The initial and operating conditions are presented in Table 2.4. The data

have been fixed at these values by a careful examination of the available

data tapes. In Appendix A the input decks for experiment 3216 are given

for both the steady state calculation as well as the transient calculation

(restart of the steady state calculation). The input decks for the other

experiments can be obtained from Appendix A by replacing some data according to Table 2.4.
- 23 -

Table 3.1. Sensitivity analyses performed for experiment no. 4100

Run no. Volume length Number of mesh Maximum time

(in) intervals () step size (s)

1 .125 16 0.01

2 .125 32 0.01

3 .25 32 0.01

1 4 1 .50 32 0.01
- 24 -

TS~vte 5 .

945 " t .126

HCATE

LA*Neli

SA "

rid

Msis .125

asoe? Us*

SteS as 1A1

Ite as An

Mt1 .1All

IThOMJUN lie

TWOVVM ISt

PIP

MIS2 M

MO0AUZATWN 916I5

teAI Ia

WOODAUXATION SOi6

POO a

an tm ww

a" TUO"I'L

0001

MOVARMOR

4" is

TUGFVOL no

a" 810" .28

a" is As

a" a .24

AS

if

""Me .20

LEMOT" a" as is gas w

LO Id

a" 07 is

8"" is

a" so AS

a" 64 if

life$ .129

let .189

I TWONW lie

5555 .5

Ste 5 .me1

4te 441 5 I

hKATSD

LzENGT

&.5

F

.30

pipe

5.5CM

M95 " Las

815 51 Al5

WMPiNW III

WO@AUZATiO" ScHma

RUN 9

Us WISH WrK*VALZ

WOCAURATION saHIMs

RUN 4

as Was" SNM2VALS

Figure 3.1. Nodalization schemes for sensitivity study.
- 25 -

Figure 3.2. EXP 4I100; Wall temperatures at level 2.

TIME (SEC)

Figure 3.3. EXP 4100; Wall temperatures at level 3.
- 26 -

9501 1

ISEPARATO

410 ] .25

41002I 41003 I MDP VOL 955

HEATED

LENGTH

3.0 M

310 15 .125

310 14 .25

310 13 .25

310 12 .25

310 11 .25

310 10 .25

310 09 .25

310 08 .25

310 07 ,.25

310 06 .25

310 05 .25

310 04 .25

3 10 03 .125

310 02 .125

310 01 1.125

XI TMDPVOL TDPJN 115 I

NODALIZATION SCHEME

PIPE

3.25 M

Figure 3.4I.
- 27 -

4. RESULTS

Comparisons between predictions with the code RELAP5/MQD2 and selected

test data from the ECN-reflood experiments [2) are described below.

4.1. Sensitivity analyses

The results of the sensitivity analyses as described in chapter 3.1

can be summarized as follows:

" The results of the coarse node model calculations (0.50 m) deviate

significantly from the results obtained with the fine node model

(0.125 and 0.25 in).

" The number of axial fine mesh intervals (16 or 321 does not influence

the calculated temperature time histories significantly as can be seen

in Fig. 3.2 and 3.3.

Based on these conclusions the nodalization as presented in Fig. 3.4. is

applied for the analyses.

4.2. RELAP5/MOD2 results vs experimental data

Code predictions are compared with the following measured quantities:

"Integrated boundary mass flows.

"Liquid mass inventory in the bundle.

"Collapsed liquid level.

"Quench front position.

"Wall temperatures at different levels.

Comparisons between code predictions and test data for the seven

selected reflood experiments are presented as follows:

Experiment 3216: figures 4.1 - 4.8.

Experiment 3224; figures 4.9 - 4.16.

Experiment 4100; figures 4.17 - 4.24.

Experiment 4106; figures 4.25 - 4.32.

Experiment 4120; figures 4.33 - 4.40.

Experiment 4138; figures 4.41 - 4.48.

Experiment 4149: figures 4.49 - 4.56.
- 28 -

4.3. Analysis of results

The calculations have been performed with the code RELAP5/MOD2 using the

available reflood model. As already mentioned in the previous section the

number of axial mesh intervals during reflood is set to 16 and the nodalization presented in Fig. 3.4 is applied. The reflood model has to be

activated at the start of each calculation. The reflood heat transfer

package in the code RELAP5/MOD2, however, is only valid for flow patterns

occurring at high reflood velocities (inverted annular flow). As for low

reflood velocities a different flow pattern occurs (annular flow) a herewith corresponding heat transfer package should have been applied. For

this reason agreement between calculated and experimental data can be expected for high reflood velocities. Only at these high reflood velocity

conditions a flow pattern with the quench front below the collapsed liquid

level will occur.

In Figs. 4.57 through 4.70 the RELAP5/MQD2 calculated and the experimental

results concerning quench front position and collapsed liquid level are

presented for the different selected cases.

Only for experiment 4120 the condition of a quench front below the collapsed liquid level is met as can be seen in Figs. 4.65 and 4.66. For this

experiment the calculated values compare in general well with the experimental results as presented in Figs. 4.33 through 4.40.

Figs. 4.71 through 4.78 show the calculated and measured heat flux at

axial level 5, 6, 7, and 8 for experiment 4120. These figures show that

near the quench front the calculated heat flux is overpredicted and that

well above the quench front the heat flux is underpredicted. This explains

the overprediction of the wall temperatures below the quench front and the

underprediction of the wall temperatures above the quench front as presented in Figs. 4.39 and 4.40. The approach of the quench front causes a

faster wall temperature decrease in the calculation due to an overestimation of the heat transfer and so the heat flux. Except for level 8 the

calculated wall temperatures for experiment 4100 show the same good agreement as described above for experiment 4120 (Figs. 4.23 and 4.24). This

agrees well with the above stated simplification in the RELAP5/MOD2 reflood model concerning heat transfer and flow regime. Experiment 4120 as

well as experiment 4100 have a high reflood velocity leading to the inverted annular flow regime identical to the model in REL.AP5/MOD2.
- 29 -

The calculated wall temperatures for experiments 3216 and 3224 show a

large deviation from the experimental data (Figs. 4.7 and 4.8 and Figs.

4.15 and 4.16). These experiments have a low reflood velocity and for that

reason do not experience the inverted annular flow regime. For this reason

the heat transfer is widely underpredicted. Poor comparison results are

also obtained for experiment 4106, 4138, and 4149 where the quenching or~

the higher levels starts far too late or not at all. The calculated quenching of level 2 and 3 in these experiments is reasonably predicted.

cFigs. 4.31 and 4.32, Figs. 4.47 and 4.48, and Figs. 4.55 and 4.56).

For almost all calculations the liquid carry-over is grosly overpredicted

and this results in an underprediction of the collapsed liquid level. The

overprediction of the carry-over of the water at the bundle outlet is that

an overprediction of the interphase drag in rod bundle geometries.

4.4. Suggestions for model improvements

As the reflood heat transfer package in the code RELAP5/MOD2 is only valid

for flow patterns occurring at high reflood velocities (inverted annular

flow) implementation of heat transfer correlations for other flow patterns

(annular flow) during reflood is recommended. Most of the RELAP5/MOD2

assessment work indicates an overprediction of the carry-over due to an

overprediction of the interfacial drag. This deficiency of the code is

also demonstrated in these analyses. For this reason the introduction of

a better correlation for the interfacial friction in the bubbly and slug

flow regimes is suggested.

4.5. User guidelines

User recommendations in the RELAP5/MOD2 manual suggest a length of the

hydrodynamic nodes between 0.15 and 0.61 m, and a maximum number of axial

fine mesh intervals equal to 16 or 32. The recommended maximum time step

size should range between 0.01 and 0.05 seconds. In the base case

RELAP5/MOD2 input model for the presented reflood analyses the length of

the hydrodynamic nodes is 0.25 m with a maximum number of 32 axial fine

mesh intervals at the quench level. The maximum time step equals to 0.01

second.
- 30 -

C

0.

C.,

0.0 100.0 200.0 300.0

TIME (SEC)

Figure 4.1. EXP 3216; Mass injected.

C.,

0.0 100.0 200.0 300.0

TIME (SEC)

Figure 4.2. EXP 3216; Mass steam out.

600.0
- 31 -

0.0 100.0 200.0 300.0 400.0 50 .0.0 600.0

TIV.E (SEC)

Figure 4.3. EXP 3216; Total mass carry-over.

.. .. . . . . . . . .. . . . . .. . .

xC,......................

0XE N

o ______ _____ *..*....RELAP /MOD2 ____

0.0 100.0 200.0 300.0 1900.0 500.0 600.0

TIM~E (SEC)

Figure 4.4. EXP 3216; Mass in the bundle.
- 32 -

0.0 100.0 200.0 300.0 A00.0 500.0 600.0

TIME (SEC)

Figure 4{.5. EXP 3216; Collapsed liquid level.

z

-j

-cEXPERIMENT

RELAP5/MOD2

O.0 100.0 200.0 300.0 A00.0 500.0 600.0

-IM.E (SEC)

Figure 4.6. EXP 3216; Quench front position.
- 33 -

TIME (SEC)

Figure 14.7. EXP 3216; Wall temperatures at level 2, 3, 4j.

R

7-7 0 XEIEN EE I- G---o EXPERIMENT LEVEL 5

It0- EXPERIMENT LEVEL 67 iP

c; -+ EXPERIMENT LEVEL 7 w

2 .RELAP5/MOD2 LEVEL 56 - c!** RELAP5/MOD2 LEVEL 6

g **.RELAP!S/MOD2 LEVEL 8

M- 0,4 5 Li

300.0

TIME (SEC)

Figure ~4.8. EXP 3216; Wall temperatures at level 5, 6, 7, 8.
-- 34 -

-I

w

0.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0

TIVE (SEC)

Figure 4.*9 . EXP 3224; Mass injected.

800.0

Figure 4.10. EXP 3224; Mass steam out.
- 35 -

(n(n

0.0 100.0 200.0 300.0 400.0 500.0 600.0

TIME (SEC)

Figure 4.11. EXP 3224; Total mass carry-over.

800.0

0

*0

-7

07 _ _ __ _

EXPERIMENT I.RELAP5/MOD2 0.0 100.0 200.0 300.0 400.0 500.0

I I __________ I I _____ _____ _____

o I I _________________

TIME (SEC)

Figure 4.12. EXP 3224; Mass in the bundle.

600.0 700.0 800.0
- 36 -

0.0 100.0 200.0 300.0 400.0 500.0 600.0

TIM'E (SEC)

Figure 4.13. EXP 3224; Collapsed liquid level.

800.0

0.0 100.0 200.0 300.0 400.0 500.0 600.0 800.0

TIME (SEC)

Figure 4.14. EXP 3224; Quench front position.
- 37 -

0.0 50.0 100.0 150.0 200.0

TIME (SEC)

Figure 4.15. EXP 3224; Wall temperatures at level 2, 3, 4.

R

o --- EXPERIMENT LEVEL 5 0I.

h-; EXPERIMENT LEVEL 6 ___

0CEXPERIMENT LEVEL 6 - ____ c-__

EXPERIMENT LEVEL 8

v .....

.RELAPS/MOD2 

vEE~j- RLP5MD RELAP5/MOD2 

LEVEL 

LEVEL 

56_ 

67 ___ _______

_ I_ o u-.RELAPS/MOD2 LEVEL rýý

C; 11_1 __ LL.

0C!0. 0. 000 £00 500 60. 0 0

1IME (SEC)

Figure 4.16. EXP 3224; Wall temperatures at level 5, 6, 7, 8.
- 38 -

0.0 50.0 100.0 150.0 200.0

TIME (SEC)

Figure 4.17. EXP 4l100; Mass injected.

0.0 50.0 100.0 150.0 200.0

TIM: (SEC)

Figure 4.18. EXP 4100; Mass steam out.
- 39 -

0.0 50.0 100.0 150.0 200.0 250.0

TIME (SEC)

Figure 4.19. EXP 4100; Total mass carry-over.

0.0 50.0 100.0 150.0 200.0 250

TIME (SEC)

Figure 4.20. EXP 4100; Mass in the bundle.

350.0
- 4o -

I

A_ _ I_ _

C -

0.0 50.0 100.0 150.0 200.0 250.0 300.0 30.

TIME (SEC)

Figure 4.21. EXP 4100; Collapsed liquid level.

00

__________ _________ I.. o~~- __ _ _ _ _____i.._ _ _ __ _ _ _ _

150.0 200.0

TIME (SEC)

Figure 4.22. EXP 4100; Quench front position.
- 41 -

100.0

TIM~E (SEC)

Figure 4.23. EXP 4100; Wall temperatures at level 2, 3. 4.

x. 'X *o . U av 

UU.

-aEXPERIMENT LEVEL 6

S-CEXPERIMENT LEVEL 6 h EXPERIMENT LEVEL 7

...C RELAP5/MOD2 . LEVEL 5 I

o, - RELAPS/MOD2 LEVEL 6

gi .RELAP5/MOD2 LEVEL 7 ____________

a 5....RELA05/MOD2 LEVEL 8

0.0 50 .0 100 150.0 200.0 250.0 300.0 350.0

Figure 4.24. EXP 4100; Wall temperatures at level 5, 6, 7, 8.
- 42 -

400.0

TIME (SEC)

Figure 4.25. EXP 4106; Mass injected.

C!

C -~EXPERIMENT _______

RELAP5/M002 .....

70

0.0 200.0 400.0 600.0 800.0

TIME (SEC)

Figure 4.26. EXP 4106; Mass steam out.
- 4~3 -

ia

0.0 200.0 400.0 600.0

TI WE (SEC)

Figure 4.27. EXP 4106; Total mass carry-over.

P

TIME (SEC)

Figure 4.28. EXP 4106; Mass in the bundle.
- 44 -

R

GEX PERIMENT ..... RELAP5/MOD2

IV, ji- ~.Ay ~vA/ l . ..................... ............ . ..I....... ...........

In

0.0 200.0 400.0

TIME (SEC)

600.0 800.0

Figure 4.29. EXP 4106; Collapsed liquid level.

400.0

-iME (SEC)

800.0

Figure 4.30. EXP 4106; Quench front position.
- 45 -

Li

w300.0

TIME (SEC)

600.0

Figure 4.31. EXP 4106; Wall temperatures at level 2, 3, 4.

C!

3--c EXPERIMENT LEVEL 55

-0EXPERIMENT LEVEL 66 -eEXPERIMENT LEVEL 7

o -EXPERIMENT LEVEL 8 x.x RELAP5/MOD2 LEVELS5.

*oRELAP5/M002 LEVEL 6 1

v .... RELAP5/MOD2 LEVEL 7 1

a .. EAP5/MOD2 LEVEL 81 ____i

oi

0.0 200.0 400.0

TIME (SEC)

600.0 800.0

Figure 4.32. EXP 4106; Wall temperatures at level 5, 6, 7, 8.
- 46 -

0.0 50.0 100.0

NIE, (SEC)

Figure 4.33. EXP 4120; Mass injected.

En,

Figure 4.34. Exp 4120; Mass steam out.
- 47 -

0.0 50.0 100.0 150.0

TIME (SEC)

Figure 4.35. EXP 4120; Total mass carry-over.

-0.0 5C.0 110.0

71M4E (SEC)

Figure 4.36. Exp 4120; Mass in the bundle.

200.0
- 48 -

0.0 50.0 100.0 150.0

TIME (SEC)

Figure 4.37. EXP 4120; Collapsed liquid level.

0.0 50.0 100.0 150.'

TIME (SEC)

Figure 4.38. EXP 4120; Quench front position.

200.0
- 49 -

-CEXPERIMENT LEVEL 2 0CEXPERIMENT LEVEL 3 h-.EXPERIMENT LEVEL 4

PELAP5/M0D2 LEVEL 2 x ... PE' Ac5/MOD2 LEVEL 3

0 *ELAP5/MOD2 .. LEVEL 4

0.0 20.0 '0.0 60.0 80.0 100.0

TIME (SEC)

Figure 4.39. EXP 4120; Wall temperatures at level 2, 3, 4.

04

SEXPERIMENT LEVEL 5

0 -o EXPERIMENT LEVEL 6

A- EXPERIMENT LEVEL 7

I LAJc, EPERIMENT LEVEL 8

Figure 4.40. EXP 4120; Wall temperatures at level 5, 6, 7, 8.
- 50 -

C

0.

In

0.0 200.0 400.0

TIME (SEC)

Figure 4.41. EXP 4138; Mass injected.

Figure 4.42. EXP 4138; Mass steam out.
- 51 -

c;.

0. 6 . 0 .06,. 0 .

TIME (SC

Fiure44.E 418 oa 0

as ar-vr

0

0.0 200.0 400.0 600.0 800.0

TIME (SEC)

Figure 4.441 . EXP 4~138; Mass in the bundle.
- 52 -

0

EN ________________

~ ill ____ _________ _________ _________

z

0

Li -J

Li L ! .............. :

-cEXPERIMENT

................ RELA0 5/MOD2

0.0 200.0 400.0

TIME (SEC)

600.0 800.0

Figure 4.45. Exp 4138; Collapsed liquid level.

400.0

TIME (SEC)

Figure ~4.46. Exp 4138; Quench front position.
- 53 -

0.0 100.0 200.0 300.0 40c.0 500.0 600.0 700.0

IME (SEC)

Figure 4.47. EXP 4138; Wall temperatures at level 2, 3, 4.

C!

CL 3- EXPERIMENT LEVEL 5

U 0-C EXPERIMENT LEVEL 6

P - EXPERiMENT LEVEL 7; 00- EXPERIMENT LEVEL B ____ T x .... RELAP5/MOD2 LEVEL 5

* RELAP5/MOD2 LEVEL 6

9)ELAP5/MOD2 .7 LEVEL 7! a R~ELA-5/MO02 LEVEL 8

0.0 200.0 400.0 600.0 800.0

TIME (SEC)

Figure 4.48. EXP 4138; Wall temperatures at level 5, 6, 7, 8.
- 54 -

0.0 100.0 200.0 300.0 400.0 500.0 600.0

TIME (SEC)

Figure 4.49. Exp 4{14 9; Mass injected.

I

300.0

TIME (SEC)

600.0

Figure 4.50. EXP 4149; Mass steam out.
- 55 -

0.0 100.0 200.0 300.0 AOO.0

TIME (SEC)

Figure 41.51. EXP 41149; Total mass carry-over.

0.0 100.0 200.0 300.0 A60.0

TIME (SEC)

Figure 4.52. Exp 4149; Mass in the bundle.
- 56 -

0.0 160.0 260.0 300.0 400.0 500.0 600.0

TIME (SEC)

Figure 4.53. Exp 4149; Collapsed liquid level.

0.0 100.0 200.0 300.0 400.0

TIME (SEC)

Figure 4.54. EXP 4149; Quench front position.
- 57 -

200.0

TIME (SEC)

Figure 4.55. Exp 414I9; Wall temperatures at level 2, 3, 4t.

D--- EXPERIMENT LEVEL 5

IL -C EXPERIMENT LEVEL 6 h EXPERIMENT LEVEL 7 a EXPERIMENT LEVEL 8

ix ... RELAP5/MOD2 LEVEL 5

*... RELAP5/MOD2 LEVEL 6

SRELAc'5/MOD2 LEVEL 7

*... ELAP5/MOD2 LEVEL 8

C?

0

0. 0. 6. 3c!0.0 A00.0 500.0 6ý0.0

TIME (SEC)

Figure 41.56. EXP 4149; Wall temperatures at level 5, 6, 7, 8
- 58 -

EXPERIMENTAL RESULTS

300.0 T

Ih.A (EC

600.0

Figure 4.57. EXP 3216; Experimental quench front and collapsed

liquid level.

RELAP5/MOD2 RESULTS

0

0

.... QUENCH FRONT -COLLAPSED IO.LEVEL

0.0 100.0 200.0 300.0 400.0 500.0 600

TIME (SEC)

.0

Figure 41.58. EXP 3216; Calculated quench front and collapsed

liquid level.
- 59 -

EXPERIMENTAL RESULTS

z

0,

0.0 100.0 200.0 300.0 0.0 500.0 600.0 700.0 800.0

-IVE (SEC)

Figure 4.59. EXP 3224; Experimental quench front and collapsed

liquid level.

RELAP5/M0D2 RESULTS

02W

†...U ENCH FRONT -COLLAPSED LIO.LEVEL _______

00200400.0 600.0 800.0

TIME (SEC)

Figure 4.60. EXP 3224; Calculated quench front and collapsed

liquid level.
- 60 -

EXPERIMENTAL RESULTS

0.0 50.0 100.0 150.0 200.0 250.C 30C.0 350.0

'rI).E (SEC)

Figure 4.61. Exp 4100; Experimental quench front and collapsed

liquid level.

RELAP5/MOD2 RESULTS

QUENCH FRONT.....

o -COLLAPSED UQ.LEVEL

z

0

FA

.0 5 .0 100.0

TIME (SEC)

250.0 300.0 350.0

Figure 4.62. EXP 4100; Calculated quench front and collapsed

liquid level.
- 61 -

EXPERIMENTAL RESULTS

400.0

Figure 4.63. EXP 4106; Experimental quench front and collapsed

liquid level.

RELAP5/M0D2 RESULTS

a

Figure 4.64. Exp 4106; Calculated quench front and collapsed

liquid level.
- 62 -

EXPERIMENTAL RESULTS

0.0 50.0 100.0 150.0 200.0

TIVE (SEC)

Figure 4.65. EXP 4120; Experimental quench front and collapsed

liquid level.

RELAP5/MOD2 RESULTS

TIME (SEC)

Figure 4.66. ExP 4120; Calculated quench front and collapsed

liquid level.
- 63 -

EXPERIMENTAL RESULTS

0.

-1

Li

0.0 203.0 '00.0 600.0 800.0

-IV--- (SEC)

Figure 4.67. ExP 4138; Experimental quench front and collapsed

liquid level.

RELAP5/MO02 RESULTS

TIME (SEC)

Figure 4.68. ExP 4138; Calculated quench front and collapsed

liquid level.
- 64 -

EZ(PERA.4ENTAL .RESUL-TS

Figure 4.69. Exp 4149; Experimental quench front and collapsed

liquid level.

RELAP5/MOD2 RESULTS

QUENCH FRONT ..... ....

-COLLAPSED UIQ.LEVEL

z __ _____ _ _ ___ ____ __ ____ ___ ___ ____ ___ ____ __ ___.___........._ ___

00 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Hi

7/ý,AnA A A

oQ A

C? I_

two. 200.0 300.0

TIME (SEC)

400.0 500.0 600.0

Figure 4.70. EXP 4149; Calculated quench front and collapsed

liquid level.
-. 65-

C'4

X

0.0 30.0 60.0 90.0 120.0 150.0 180.0 210.0

Figure 4.71. EXP 4120;- Calculated heat flux at level 5.

TIMlE [SEC)

Figure 4.72. EXP 4120; Experimental heat flux at level 5.
- 66 -

CCý

0.0 30.0 60.0 90.0 120.0

TIME (SEC)

150.0 180.0 210.0

Figure 4.73. EXP 4120; Calculated heat flux at level 6.

ME.1 ISM~

Figure 4.74. EXP 4120; Experimental heat flux at level 6.
- 67 -

90.0 120.0

TimE- (SEC)

Figure 4.75. EXP 4120; Calculated heat flux at level 7.

HEAT fLUX TO COCLA.'4T VS TIM. 0 2

Ue 1l2,1322,23.33 LEVEL7

A -

+. 2..

S23 -

a4

n~I

C!

Figure 4.76. ExP 4120; Experimental heat flux at level 7.
- 68 -

.00*

* N

0

1*

I.-o I I I.,i I-I

6 _ _ I_ _ _ _ _ _ _ _

.30.0 60.0 90.0 120.0 TIME (SEC)

1s0.0 480.0 210.0

Figure 4.77. EXP 4120; Calculated heat flux at level 8.

b

ý"-. 0

Figure 4.78. EXP 4120; Experimental heat flux at level 8.
- 69 -

5. RUN STATISTICS

The number of system seconds and the CPU time used for the four sensitivity analyses as presented in section 3.1. are given in Table 5.1. The numbers are based on 100 seconds process time. The analyses are performed on

the Cyber 855 mainframe computer of the Technical Computing Center (ENR)

at Petten, the Netherlands.

Table 5.1. Run statistics.

Length of the Axial fine CPU Process time

hydrodynamic nodes mesh intervals (s) (S)

Run 1; Exp. 100 .125 m 16 2429 100

Run 2; Exp. 4100 .125 m 32 2554 100

Run 3; Exp. 4100 . 25 m 32 909 100

Run 4; Exp. 4100 . 50 m 32 15931 100
- 70 -

6. CONCLUSIONS

The conclusions concerning the RELAP5/MOD2 analyses of some selected

reflood experiments can be summarized as follows:

- The reflood heat transfer model in RELAP5/MOD2 is only valid for high

reflood rates. This is the main reason that cladding temperatures are

well predicted for high reflood velocities (0.08 m/s) while a poor comparison is obtained for low reflood velocities (0.015 m/s).

Modification of the heat transfer model to include low reflood rates is

recommended.

- Entrainment of water in the bundle is strongly overpredicted for all

selected cases. For this reason modifications of the interfacial friction correlations for the bubbly and slug flow regime are recommended.

- Refinement of the axial nodalization (axial nodes smaller than recommended in the RELAP5/MOD2 users guidelines) does not improve the calculational results.
- 71 -

REFERENCES

[1) Ransom, V.H. et al.:

RELAP5/MOD2 Code Manual,

NUREG/CR-4312. August 1985.

[2] Boer. T.C., de; Molen, S.B., van der,eta.

Heat Transfer to a Dispersed Two-Phase Flow and Detailed Quench

Front Velocity Research, CEO Report EUR 10074 EN, 1985.

[3] Code improvement plan for TRAC-PF1 and RELAP5, INEL, November

1987. DRAFT.

[4] Compendium of ECCS Research for Realistic LOCA Analysis.

NUREG-1230, April 1987. DRAFT.

[5] Guidelines and Procedures for the International Code Assessment

and Applications Program. NUREG-1271, April 1987.
- 72 -

LIST OF TABLES Page

1.1. Comparison of some reflood experimental facilities. 9

2.1. Range of initial test conditions for the analyzed reflood 13

experiments

2.2. Test matrix for the ECN-reflood program. 14

2.3. Selected experiments. 15

2.4. Initial and operating conditions. 16

3.1. Sensitivity analyses performed for experiment no. 4100. 23

5.1. Run statistics. 69
- 73 -

LIST OF FIGURES Page

2.1. ECN-reflood test facility schematics. 17

2.2. Test section and steam/water separator. 18

2.3. Reflood instrumentation in 36-rod bundle. 19

2.4. Cross-section of the bundle with thermocouple positions. 20

3.1. Nodalization schemes for sensitivity study. 24

3.2. EXP 4100; Wall temperatures at level 2. 25

3.3. EXP 4100; Wall temperatures at level 3. 25

3.4. Nodalization scheme. 26

4.1. EXP 3216; Mass injected. 30

4.2. EXP 3216; Mass steam out. 30

4.3. EXP 3216; Total mass carry-over. 31

4.4. EXP 3216; Mass in the bundle. 31

4.5. EXP 3216; Collapsed liquid level. 32

4.6. EXP 3216; Quench front position. 32

4.7. EXP 3216; Wall temperatures at level 2, 3, 4. 33

4.8. EXP 3216; Wall temperatures at level 5, 6, 7, 8. 33

4.9 EXP 3224; Mass injected. 34

4.10. EXP 3224; Mass steam out. 34

4.11. EXP 3224; Total mass carry-over. 35

4.12. EXP 3224; Mass in the bundle. 35

4.13. EXP 3224; Collapsed liquid level. 36

4.14. EXP 3224; Quench front position. 36

4.15. EXP 3224; Wall temperatures at level 2, 3, 4. 37

4.16. EXP 3224; Wall temperatures at level 5, 6, 7, 8. 37

4.17. EXP 4100; Mass injected. 38

4.18. EXP 4100; Mass steam out. 38

4.19. EXP 4100; Total mass carry-over. 39

4.20. EXP 4100; Total mass in the bundle. 39

4.21. EXP 4100; Collapsed liquid level. 40

4.22. WX 4100; Quench front position. 40

4.23. Exp 4100; Wall temperatures at level 2, 3, 4. 41

4.24. EXP 4100; Wall temperatures at level 5, 6, 7, 8. 41

4.25. EXP 4106; Mass injected. 42
- 74 -

Page

4.26. EXP 4106; Mass steam out. 42

4.27. ExP 4106; Total mass carry-over. 43

4.28. EXP 4106; Mass in the bundle. 43

4.29. EXP 4106; Collapsed liquid level. 44

4.30. EXP 4106; Quench front position. 44

4.31. EXP 4106; Wall temperatures at level 2, 3, 4. 45

4.32. Exp 4106; Wall temperatures at level 5, 6, 7, 8. 45

4.33. EXP 4120; Mass injected. 46

4.34. EXP 4120; Mass steam out. 46

4.35. EXP 4120; Total mass carry-over. 47

4.36. EXP 4120; Mass in the bundle. 47

4.37. EXP 4120; Collapsed liquid level. 48

4.38. EXP 4120; Quench front position. 48

4.39. EXP 4120; Wall temperatures at level 2, 3, 4. 49

4.40. EXP 4120; Wall temperatures at level 5, 6, 7, 8. 49

4.41. ExP 4138; Mass injected. 50

4.42. ExP 4138; Mass steam out. 50

4.43. EXP 4138; Total mass carry-over. 51

4.44. ExP 4138; Mass in the bundle. 51

4.45. EXP 4138; Quench liquid level. 52

4.46. EXP 4138; Quench front position. 52

4.47. EXP 4138; Wall temperatures at level 2, 3, 4. 53

4.48. EXP 4138; Wall temperatures at level 5, 6, 7, 8. 53

4.49. EXP 4149; Mass injected. 54

4.50. EXP 4149; Mass steam out. 54

4.51. EXP 4149; Total mass carry-over. 55

4.52. EXP 4149; Mass in the bundle. 55

4.53. EXP 4149; Collapsed liquid level. 56

4.54. EXP 4149; Quench front position. 56

4.55. ExP 4149; Wall temperatures at level 2, 3, 4. 57

4.56. EXP 4149; Wall temperatures at level 5, 6, 7, 8. 57

4.57 EXP 3216; Experimental quench front and collapsed liquid level. 58

4.58 EXP 3216; Calculated quench front and collapsed liquid level. 58

4.59 EXP 3224; Experimental quench front and collapsed liquid level. 59

4.60 EXP 3224; Calculated quench front and collapsed liquid level. 59
- 75 -

Page

4.61 EXP 4100; Experimental quench front and collapsed liquid level. 60

4.62 EXP 4100; Calculated quench front and collapsed liquid level. 60

4.63 EXP 4106; Experimental quench front and collapsed liquid level. 61

4.64 ExP 4106; Calculated quench front and collapsed liquid level. 61

4.65 EXP 4120; Experimental quench front and collapsed liquid level. 62

4.66 EXP 4120; Calculated quench front and collapsed liquid level. 62

4.67 EXP 4138; Experimental quench front and collapsed liquid level. 63

4.68 EXP 4138; Calculated quench front and collapsed liquid level. 63

4.69 EXP 4149; Experimental quench front and collapsed liquid level. 64

4.70 EXP 4149; Calculated quench front and collapsed liquid level. 64

4.71 EXP 4120; Calculated heat flux at level 5. 65

4.72 EXP 4120; Experimental heat flux at level 5. 65

4.73 EX? 4120; Calculated heat flux at level 6. 66

4.74 EXP 4120; Experimental heat flux at level 6. 66

4.75 EXP 4120; Calculated heat flux at level 7. 67

4.76 EXP 4120; Experimental heat flux at level 7. 67

4.77 EXP 4120; Calculated heat flux at level 8. 68

4.78 EXP 4120; Experimental heat flux at level 8. 68

Win4ll. rap
- 76 -

Appendix A. RELAP5/MOD2 input deck.

=REFLOOD Exp 3216

100

101

NEW

RUN

STDY-ST

*TIME STEPS

201

END

0.5

MIN

.5E-4

MAX

. 01

3101

3101

CTRL~ MINED MAJED REST

202 25 1000 1250

*****20800001 TREWET

*****20800002 ZTRWT

*MINOR EDITS

301

303

304

305

306

307

308

309

*TRIPS

p

ZTRWI

HTTEMP

HTTEMP

HTTEMP

HTTEMP

HTTEMP

HTTEMP

HTTEMP

310150000

3101

310100505

310100705

310100905

310101105

310101205

310101305

310101405

501

510

520

530

600

T IME

T IME

T IME

T IME

501

0

0

0,

0

GT

GT

GT

GT

NULL

NULL

NULL

NULL

0

0

0

0

1000. N

10.0 L

10. 0 L

.0 L

*POWER

*FILL FLOW

*REFLOOD

* * * * * *** ***

* * * ** * * * *

* **** * * * ****

*** ** * * ***

* * * **** * *

* * * ** * ****

*VOLUMES

01100000

01100101

01100102

01100200

01100201

* * * * * ** * * * ** * * **

* *** * * ** *** ** * * * * **

INLET

1000000.

4 . OE-5

3

0.

TMDP VOL

100.

0.0

.0

00

.0 90. 100.

200000. 313.
- 77 -

03100000

03100001

03100101

03100201

03100202

03100203

03100204

03100205

03100206

03100207

03100208

03100209

03100210

03100211

03100212

03100213

03100214

03100301

03100302

03100303

03100601

03100801

03100901

03100902

03100903

03100904

03100905

03100906

03100907

03100908

03100909

03100910

03100911

03100912

03100913

03100914

03101001

03101101

03101201

03101202

03101203

03101204

03101205

03101206

03101207

03101208

03101209

03101300

03101301

HEATER

15

.004785

.0

.004188

.0

.004188

.0

.004188

.0

.004188

.0

.004188

.0

.004188

.0

.125

.25

.125

90.

4 . OE-5

.0

.0

.0717

.0

.0717

.0

.0717

.0

.0717

.0

.0717

.0

.0717

.0

00

31000

3

0

3

3

3

3

3

3

3

1

.0

PIPE

15

1

2

3

4

5

6

7

8

9

10

11

12

13

14

3

14

15

15

. 0118

.0

.0

.0717

.0

.0717

.0

.0717

.0

.0717

.0

.0717

.0

.0717

.0

15

14

201309.

200105.

200029.

200027.

200024.

200017.

200007.

200005.

15

1

2

3

4

5

6

7

8

9

10

11

12

13

14

313.0 .0 .0 .0

166795. 2529480. .10 .0

463. .0 .0 .0

463. .0 .0 .0

463. .0 .0 .0

463. .0 .0 .0

463. .0 .0 .0

463. .0 .0 .0

1

2

3

4

5

12

13

14

200003. 463. .0 .0 .0 15

.0 .0 14
- 78 -

04100000

04100001

04100101

04100102

0 4100200

04101101

04101201

04102101

04102201

04103101

04103201

09500000

09500101

09500102

09500200

09500201

09550000

09550101

09550102

09550200

09550201

01150000

01150101

01150200

01150201

01150202

01150203

01150204

UPPLEN

3

. 004785

4. OE-5

3

410010000

0.0

410000000

0.0

310010000

0.0

OUTLET

1000000.

4. OE-5

3

0.

OUTLET

1000000.

4. OE-5

3

0.

INLET

110000000

0

0.0

4.9

5.0

805.0

SEPARATR

0

.25

.0118

200000.

950000000

0.0

955000000

0.0

410000000

0.0

TMDP VOL

100.

0.

0.

00

453.

.004785

0.0

.004785

0.0

.004785

0.0

0.

.5

.5

.0

90.

.5

.5

.0

.25

31000

31000

31000

.0

00

.0 90. 100.

200000. 453.0

TMDP VOL

100.

0.

.0

00

.0 90. 100.

200000. 453.0

TMDP JUN

310 00 000 0

520

.0

.0

.015486

.014356

.0

.0

.0

.0

.0

.0

.0

.0

.0
- 79 -

* * *

* * *

* ****

*

*

** *

*

**** *****

* *

** *

* *

* * * *

* * * ****

*

* * * ** * * * * **

* * * ** **** * * * **

13101000

13101100

13101101

13101102

13101103

13101104

13101201

13101202

13101203

13101204

13101301

13101302

13101303

13101400

13101401

13101402

13101403

13101404

13101405

13101406

13101407

13101408

13101409

13101410

13101411

13101412

13101413

13101414

13101415

13101501

13101502

13101503

13101601

13101602

13101603

13101701

13101702

13101703

13101704

13101901

15

0

1

1

1

1

1

2

1

3

0.

1 .

0.

-1

313.

330.

441.

445.

450.

454.

459.

461.

463.

468.

473.

473.

464.

449.

433.

0

0

0

310010000

310040000

310150000

777

777

777

777

0

5

102

.0023

.00446

.00535

2 0 0. 530 1 32

1

2

3

4

1

2

4

441.

445.

450.

454.

459.

461.

463.

468.

473.

473.

464.

449.

433.

0

0

0

10000

10000

0

.0

.0416666

.0833333

.0416666

.0118

313.

330.

441.

445.

450.

454.

459.

461.

463.

468.

473.

473.

464.

449.

433.

0

0

0

1

1

1

. 0

.0

.0

.0

.0

313.

330.

441.

445.

450.

454.

459.

461.

463.

468.

473.

473.

464.

449.

433.

1

.0

313.

330.

441.

445.

450.

454.

45.9.

461.

463.

468.

473.

473.

464.

449.

433.

4.0

8.0

4.0

4.0

8.0

4.0

2

3

14

15

15

3

14

15

3

14

15 -
- 80 -

* ***** * * ***** ***

* * * * *

* * **** ****

* * *.* *

* * * * *****

*

*

* *

*** ***

* * * *

****  

**  ** * ** **

* * ** * * * **

20100100

20100101

20100151

20000

20100200

20100201

20100251

20100300

20100351

20100352

*TABLES

20770

20277700

TBL/FCTN

20 .0

3.22E+6

TBL/FCTN

16.7

3.2 66E+6

TBL/FCTN

1 1 *BORONNITR.

1 1 *HETER

1 1

273.15 12.9805

255.37 3561611.

533.15 4233615.

699.82 4502416.

2000.00 5376019.

* CLAD

1199.82 25.1060

422.04 3964814.

588.71 4334415.

810.93 4636816.

2000.0 25.1060

477.59

644.26

1366.48

4099214.

4435081.

5376019.

POWER 510 1 . 1 .

0.0 426. 14.5 426. 17.5 114805.3 587.5 115736.9
- 81 -

* CONTROL VARIABLES

20500100

20500101

20500102

20500103

20500104

20500105

20500106

20500107

20500108

20500109

20500110

20500111

20500112

20500113

20500200

20500201

20500202

20500203

20500300

20500301

20500302

20500303

20500400

20500401

20500402

20500403

20500500

20500501

20500600

20500601

20500700

20500701

20500800

20500801

20500802

20500803

COLLVL

0.0

STEAM-OUT

VELGJ

RHOGJ

VO IDGJ

WATER-OUT

VELFJ

RHOFJ

VOIDFJ

WATER-IN

VELFJ

RHOFJ

VOIDFJ

INJECTED

CNTRLVAR

S TEAM- OUT

CNTRLVAR

WATER-OUT

CNTRLVAR

MAS S

0.0

sum

0.125

0.250

0.250

0.250

0.250

0.250

0.250

0.250

0.250

0.250

0.250

0.250

0.125

MULT

410030000

410030000

410030000

MULT

410030000

410030000

410030000

MULT

115000000

115000000

115000000

INTEGRAL

4

INTEGRAL

2

INTEGRAL

1.0

VOIDF

VOIDF

VOIDF

Va IDF

VO IDF

VOIDF

VOIDF

VOIDF

VOIDF

VOIDF

VO IDF

VO IDF

VO IDF

.004785

0.0 1

310030000

310040000

310050000

310060000

310070000

310080000

310090000

310100000

310110000

310120000

310130000

310140000

310150000

0.0 1

.004785 0.0 1

.004785 0.0 1

1.0

1.0

1.0

0.0

0.0

0.0

1

1

1

sum 1

1.0

1.0 10.0

CNTRLVAR

CNTRLVAR

CNTRLVAR

-1.0

-1.0

S5

6

7
- 82 -

R EFLOOD EXP 3216

100

101

103

RE START

RUN

54

TRANSNT

*TIME STEPS

201

END MIN

550.0 .5E-4

MAX

.01

CTRL MINED MAJED REST

202 25 1000 1250

20800001

20800002

TREWET

ZTRWT

3101

3101

*MINOR EDITS

301

302

303

304

305

306

307

308

*TRIPS

501

510

520

530

600

20010

20501000

P

ZTRWT

HTTEMP

HTTEMP

HTTEMP

HTTEMP

HTTEMP

HTTEMP

310010000

3101

310100505

310100705

310100905

310101105

310101305

310101405

TIME

TIME

TIME

TIME

501

0

0

0

0

GT NULL

GT NULL

GT NULL

GT NULL

0

0

0

0

1000. N *END

0.0 Ls *POWER

0.0 Ls *FILL FLOW

.0 L *REFLOOD

Q-FRONT

-0.250

sum

1.0

1.0

ZTRWT

0.0 1

3101
NRC F RM 335 U.S. NUCLEAR REGULATORY COMMISSION 1. REPORT NUMBER

12.ag,) (A~sslomd by NRC. Add Vol.. Ilwoo.. Rev.. NRcM 1102. q ad Addendum Numbers. if sav.) 3201. 320? BIBLIOGRAPHIC DATA SHEET NUREG/IA-0112

(See iflstfuctiofl on the reere ECN-C-92-008

2. TITLE AND SUBTITLE

Assessment of RELAP5/M4OD2 Against ECN-Reflood Experiments 3. DATE REPORT PUBLISHED

MONTH YEAR

July 1993

4. FIN OR GRANT NUMBER

L2245

S. AUTHOR(IS) 6. TYPE OF REPORT

A. Woudstra, J. P. A. Van De Bogaard, P. M. Stoop Technical

7. PERIOD COVERED (inclusive Direst

8. PERFORMING ORGANIZATION - NAME AND ADDRESS (II NRC.provide Division. 0/lice or Region. U.S. Nuclear Regulatory Commission, and mailling #ddrvus.it conrracror, provide

new edmesadwling addrvess.J

Netherlands Energy Research Foundation ECN

Service Unit General Services

P. 0. Box 1, NL,-1755 ZG Petten

The Netherlands

9. SPONSORING ORGANIZATION - NAME AND ADDR ESS PIlNRC. type *Tn as above"; if cantractor. Provide NRC Division. Jllice or Region. U.S. Nuclear Regulatory Commission.

and mailing edoressj

Office of Nuclear Regulatory Research

U. S. Nuclear Regulatory Commission

Washington, DC 20555 -000 1

10. SUPPLEMENTARY NOTES

11. ABSTRACT 1200 words or lear)

As part of the ICAP (International Code Assessment and Applications Program) agreement between ECN

(Netherlands Energy Research Foundation) and USNRC, ECN has performed a number of assessment calculations

with the computer program RELAP5.

This report describes the results as obtained by ECN from the assessment of the thermohydraulic computer program

RE-LAPS/MOD2/CY 36.05 versus a series of reflood experiments in a bundle geometry. A total number of seven

selected experiments have been analyzed, from the reflood experimental program as previously conducted by ECN

under contract of the Commission of the European Communities (CEC). In this document, the results of the

analyses are presented and a comparison with the experimental data is provided.

12. KEY WORDSIDESCR PTOR S (List words or phroses that will assist tesarchers In locating the reporr.i1 13. AVAI LABI LITY STATEMENT

RELAP5/MOD2, ICAP, thermohydraulic Unlimited 14. SECURITY CLASSIFICATION

iThitPage!

Unclassified

(mis Radon!

Unclassified

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