Fl L -(,-

NUREG/IA-0019

International

Agreement Report

TRAC-PF1/MOD1 Post-Test

Calculations of the OECD

Loft Experiment LP-SB-2

Prepared by

F. Pelayo

United Kingdom Atomic Energy Authority

Winfrith, Dorchester

Dorset, England

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

Washington, DC 20555

December 1990

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-0019

International

Agreement Report

TRAC-PF1/MOD1 Post-Test

Calculations of the OECD

Loft Experiment LP-SB-2

Prepared by

F. Pelayo

United Kingdom Atomic Energy Authority

Winfrith, Dorchester

Dorset, England

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

Washington, DC 20555

December 1990

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 is based on work performed under the sponsorship of the

United Kingdom Atomic Energy Authority. The information in this

report has been provided to the USNRC under the terms of the

International Code Assessment and Application Program (ICAP)

between the United States and the United Kingdom (Administrative

Agreement - WH 36047 between the United States Nuclear Regulatory

Commission and the United Kingdom Atomic Energy Authority Relating

to Collaboration in the Field of Modelling of Loss of Coolant

Accidents, February 1985). The United Kingdom has consented to the

publication of this report as a USNRC document in order to allow

the widest possible circulation among the reactor safety community.

Neither the United States Government nor the United Kingdom 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, or 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.
ABSTRACT

An analysis of the OECD-LOFT-LP-SB-2 experiment making use of

TRAC-PFl/MODl is described in the report'.

LP-SB2 experiment studies the effect of a delayed pump trip

in a small break LOCA scenario with a 3 inches equivalent

diameter break in the hot leg of a commercial PWR operating

at full power.

The experiment was performed on 14 July 1983 in the LOFT

facility at the Idaho National Engineering Laboratory under

the auspices of the Organisation for Economic Co-operation

and Development (OECD). This analysis presents an evaluation

of the code capability in reproducing the complex phenomena

which determined the LP-SB-2 transient evolution. The.

analysis comprises the results obtained from two different

runs. The first run is described in detail analysing the

main variables over two time spans: short and longer term.

Several conclusions are drawn and then a second run testing

some of these conclusions is shown.

All of the calculations were performed at the United Kingdom

Atomic Energy Establishment at Winfrith under the auspices of

an agreement between the UKAEA (United Kingdom Atomic Energy

Authority) and the Consejo de Seguridad Nuclear Espafol

(CSN).

AEEW - R 2202
ACKNOWLEDGEM4ENTS

Appreciation is expressed to all the staff members of the

LOCA'Thermal Hydraulics Group at Winfrith Establishment with

special mention to Dr C Richards and Miss E Allen for their

valuable contribution to the realisation of this work.

II

AEEW - R 2202 •"
CONTENTS

Page

ABSTRACT I

ACKNOWLEDGEMENTS II

1 INTRODUCTION 1

2 LOFT FACILITY 1

2.1 System Description 1

3 TRAC PF1 MOD1 MODEL OF LOFT FACILITY 2

3.1 Reactor Vessel 3

3.2 Steam Generator and Steam Line 4

3.3 Intact and Broken Loops 4

4 EXPERIMENT LP-SB-2 .4

4.1 Steady State Calculation 5

4.2 Transient Boundary Conditions 6

4.3 Chronology of Events for Experiment LP-SB-2 6

5 POST-TEST CALCULATIONS 7

5.1 Run A 7

5.1.1 Code Performance 7

5.1.2 Short Time Behaviour (0.0 - 850 secs) 7

5.1.2.1 Pressure Behaviour: Primary Side 8

5.1.2.2 Pressure Behaviour: Secondary Side 8

5.1.2.3 Temperatures 9

5.1.2.4 Density Distribution 9

5.1.2.5 Fluid Velocities 10

AEEW III - R 2202
CONTENTS (Contd)

Page

5.1.2.6 Transient Mass Inventory

5.1.3 Long Time Behaviour (850 - 3000 secs)

5.1.3.1 Pressure Behaviour

5.1.3.2 Temperatures

5.1.3.3 Density Distribution

5.1.3.4 Fluid Velocities

5.1.3.5 Transient Mass Inventory

5.1.4 Conclusions Derived from Run A

5.2 Run B

5.2.1 Results Review

5.2.2 Conclusions Derived from Run B

6 SELECTED ITEMS

6A LP-SB2 Pumps Modelling

6B Break Flow Density in Experiment LP-SB-2

6C Flow Regimes Prediction for LP-SB-2

7 SUMMARY AND FINAL CONCLUSIONS

REFERENCES

11

11

11

12

13

14

15

16

16

17

19

20

20

22

24

25

28

FIGURES

TABLES

32

112

APPENDIX A Run B Snapshots at Selected' Times

APPENDIX B Modifications Implemented in

TRAC-PFl/MOD1 Winfrith Versions

Bo2A and BO2C

148

149

AEEW - R 2202 IV
FIGURES

NUMBER TITLE PAGE

1 LOFT FACILITY AXONOMETRIC PROJECTION 33

2 LOFT PIPING SCHEMATIC WITH INSTRUMENTATION. 34

-3 LOFT FACILITY NODING DIAGRAM 35

4 CORE BYPASS FLOW PATHS 36

.5 ONE-DIMENSIONAL VESSEL REPRESENTATION 37

6 STEAM GENERATOR NODING 38

RUN A

7 TOTAL TIME STEPS 39

8 TIME STEP SIZE 40

- SHORT TERM (0.0 - 850 SECS)

9 INTACT LOOP HOT LEG PRESSURE 41

10 VOID FRACTION IN THE UPPER PLENUM AND BOX .42

BEFORE HOT LEG NOZZLES

11 BREAK MASS FLOW RATE 43

.12 PRESSURE DIFFERENCE OVER THE MAIN COOLANT 44

PUMPS

13 SECONDARY SIDE PRESSURE .45.!

14 LIQUID TEMPERATURE IN THE HOT LEG OF THE 46

INTACT LOOP

15 LIQUID TEMPERATURE IN THE COLD LEG OF THE 47

INTACT LOOP

16 PRIMARY AND SECONDARY PRESSURES IN TRAC .48

17 DENSITY IN THE HOT LEG OF THE .INTACT LOOP 49

18 DENSITY IN THE COLD LEG OF THE INTACT LOOP 50

AEEW - R 2202 V
FIGURES (Contd)

NUMBER TITLE PAGE

19 GAMMA DENSITOMETERS LAYOUT IN THE HOT AND 51

COLD LEG

20 VOID FRACTION AT TOP OF THE U-TUBES 52

21 LOOP SEAL DENSITY 53

22 DENSITY IN THE BREAK LINE 54

23 LIQUID AND VAPOUR VELOCITY IN THE COLD LEG 55

24 LIQUID AND VAPOUR VELOCITY IN THE HOT LEG 56

25 LIQUID AND VAPOUR VELOCITY IN THE DOWNCOMER 57

OF THE REACTOR VESSEL

26 LIQUID AND VAPOUR VELOCITY AT CORE INLET 58

27 LIQUID AND VAPOUR VELOCITY AT CORE OUTLET 59

28 LIQUID AND VAPOUR VELOCITY IN THE BREAK LINE 60

29 PRIMARY SYSTEM MASS INVENTORY 61

- LONG TERM (850 - 3000 SECS)

30 SECONDARY PRESSURE 62

31 PRIMARY AND SECONDARY SIDE PRESSURES IN TRAC 63

32 INTACT LOOP HOT LEG PRESSURE 64

33 LIQUID TEMPERATURE IN THE HOT LEG OF THE 65.

INTACT LOOP

34 COLD LEG TEM SAT - TEM LIQ 66

35 CLADDING TEMPERATURE NEAR TOP OF THE CORE 67

36 DENSITY IN THE HOT LEG INTACT LOOP 68

VI

AEEW- R 2202
FIGURES (Contd)

NUMBER TITLE PAGE

37 DENSITY IN THE COLD LEG OF THE INTACT LOOP 69

38 DENSITY IN THE BREAK LINE 70

39 LIQUID AND VAPOUR VELOCITY IN THE DOWNCOMER 71

OF THE REACTOR VESSEL

40 LIQUID AND VAPOUR VELOCITY AT CORE INLET 72

41 PRESSURE DIFFERENCE OVER THE MAIN COOLANT 73

PUMPS

42 LIQUID AND VAPOUR VELOCITY AT CORE OUTLET 74

43 LIQUID AND VAPOUR VELOCITY IN THE HOT LEG 75

44 LIQUID AND VAPOUR VELOCITY IN THE COLD LEG 76

45 LIQUID AND VAPOUR VELOCITY IN THE BREAK 77

LINE

46 HOT LEG MASS FLOW-RATE AT VENTURI LOCATION 78

47 BREAK MASS FLOW RATE 79

48 PRIMARY SYSTEM MASS INVENTORY 80

RUN B

49 BREAK LINE DENSITY 81

50 BREAK MASS FLOW RATE 82

51 PRIMARY SYSTEM MASS INVENTORY 83

52 INTACT LOOP HOT LEG PRESSURE 84

53 SECONDARY SIDE PRESSURE 85

VII

AEEW - R 2202
FIGURES (Contd)

NUMBER TITLE PAGE

54 LIQUID TEMPERATURE IN THE HOT LEG OF THE 86

INTACT LOOP

55 CLADDING TEMPERATURE NEAR TOP-OF THE CORE 87

56 DENSITY IN THE HOT LEG INTACT LOOP 88

57 DENSITY IN THE COLD LEG OF THE INTACT LOOP 89

58 LIQUID AND VAPOUR VELOCITY IN THE DOWNCOMER 90

OF THE REACTOR VESSEL

59 VOID FRACTION TOP FUEL REGIONý 91

60 LIQUID AND VAPOUR VELOCITY AT CORE INLET 92

61 LIQUID AND VAPOUR VELOCITY IN THE HOT LEG 93

62 PRESSURE DIFFERENCE OVER THE MAIN COOLANT 94

PUMPS

63 HOT LEG MASS FLOW RATE AT VENTURI LOCATION 95

64 LIQUID AND VAPOUR VELOCITY IN THE BREAK LINE 96

SELECTED'ITEMS

NUMBER TITLE PAGE

Al MEASURED AND ADJUSTED COLD LEG DENSITIES AT 97

THE STEAM GENERATOR OUTLET

A2 PUMP HEAD AS-A FUNCTION OF VOID FRACTION FOR 98

EXPERIMENTS LP-SB-2 AND L3-6

AEEW -R 2202 VIII
FIGURES (Contd)

NUMBER TITLE PAGE

A3 PUMP HEAD AS A FUNCTION OF VOID FRACTION 99

OBTAINED USING THE ADJUSTED DENSITY AT THE

STEAM GENERATOR OUTLET FOR EXPERIMENT

LP-SB-2

A4 PUMP HEAD VS VOID FRACTION IN RUN A 100

A5 LOOP SEAL DENSITY IN RUN A, 101

A6 PUMPS PRESSURE INCREASE VS VOLUMETRIC FLOW 102

RATE IN RUN A

A7 PUMPS MASS FLOW RATE IN RUN A 103

AS PRIMARY COOLANT PUMP POWER 104

A9 PUMPS TORQUES IN RUN B 105

A10 PUMPS MASS FLOWS IN RUN B 106

Bl EXPERIMENTAL HOT LEG DENSITY AND BREAK LINE 107

DENSITY

B2 NODING MODIFICATIONS IN THE BREAK LINE 108

B3 QUALITY CONTROL VALVE CONTROL LOGIC 109

Cl TRAC FLOW REGIME MAP FOR LOFT LP-SB-2 HOT 110

LEG CONDITIONS RUN B

C2 TIME VS HOT LEG VOID FRACTION IN RUN B 1il

AEEW - R 2202 IX
TABLES

NUMBER TITLE PAGE

1 INITIAL CONDITIONS FOR EXPERIMENT LP-SB-2 113

- RUN A

2 OPERATIONAL SET POINT FOR EXPERIMENT 114

.LP-SB-2

3 CHRONOLOGY OF EVENTS FOR EXPERIMENT LP-SB-2 115

- RUNA

4 INSTRUMENT LOCATIONS FLOW AREAS 116

5 INITIAL CONDITIONS FOR EXPERIMENT LP-SB-2 117

- RUN B

6 CHRONOLOGY OF EVENTS FOR EXPERIMENT LP-SB-2 118

-RUNEB.

Al PUMP HEAD MULTIPLIERS - RUN A 119

A2 PUMP HEAD MULTIPLIERS - RUN B 120

Bl DESIRED BRANCH QUALITY VS VOID FRACTION IN 121

THE HOT LEG

MIMIC DIAGRAMS

MIMIC DIAGRAMS FOR RUN B 122

AEEW - R 2202 X
COMMERCIAL IN CONFIDENCE

1 INTRODUCTION

Experiment LP-SB-2 studies the effect of a delayed pumps.trip

in a Small Break LOCA scenario with a three inches equivalent

diameter break in the hot leg of a commercial PWR operating

at full power. The experiment was performed on 14 July 1983

in the LOFT facility at the Idaho National Engineering

Laboratory under the auspices of the Organisztion for

Economic Co-operation and Development (OECD). The evolution

of the experiment was determined by several features, among

the most important of which were the flow patterns present in

the loop, vapour pull-through and liquid entrainment observed

in the break line, and pumps behaviour.

Early in the transient a density gradient developed in the

vertical section of the hot leg. The break line density was

sensitive to this gradient; moreover a preferential flow of

steam was detected as soon as two-phase conditions occurred.

Under stratified conditions and later in the transient, the

break suddenly uncovered increasing the d~pressurisation

rate; from then on some liquid entrainment was observed to

occur.

The pumps behaviour was important in determining the fluid

velocities and density distribution as well as changes in

flow distribution and flow patterns in the loop.

Many of the features of TRAC-PFl/MODl were used 'during the

analysis of the experiment, ie the flow regime dependent

constitutive equation package, choked flow model, pump model

under two-phase conditions, fluid transport and associated

two-phase pressure losses along the whole loop, etc.

The SETS numerics were applied to all the components in the

system as no three-dimensional vessel was used.

All the calculations were performed on a CRAY X-MP computer

and the Code versions used were the Winfrith versions BO2A

for RUN A and BO2C for RUN B. Both versions contain Los

Alamos updates up to Version 12.7. A description of the

difference between the Winfrith code version and Version 12.7

is given in Appendix B...

2 LOFT FACILITY

2.1 System Descripti6n .0 -

The LOFT test facility simulates a four loop PWR 1000 MW

(electric) commercial plant. It has a thermal power of 50 MW

produced by nuclear fission sustained in the reactor core.

The system was designed to simulate the major components and

system responses during LOCAs or operational transient

accidents. The facility components were instrumented to

record the main system variables during the experiments.

AEEW - R 2202 1 I. -
The facility consists of a reactor vessel volumetrically

scaled to 1/47; an intact loop with an active steam

generator, pressuriser, and two primary coolant pumps

connected in parallel; a broken loop connected by

recirculation lines to the intact loop to keep the fluid

temperature at about the core inlet temperature prior to

experiment, a reflood assist bypass valve connecting both

legs of the broken loop as a safety device, and two quick

opening valves (kept closed during SB-2 experiment)

connecting both legs of the broken loop to the suppression

tank header. During experiment LP-SB-2 the blowdown valves

and isolation valves were kept closed as the break was in the

hot leg of the "intact" loop. The broken loop spool pieces

with orifices to simulate the steam generator and pump

hydraulic resistance were not installed for this experiment,

but were replaced by a straight piping spool piece.

The LOFT ECCS simulates that of a commercial PWR. It

consists of two accumulators, a high pressure injection

system, and a low pressure injection system. Each system is

arranged to inject scaled flows of emergency core coolant

directly into the primary coolant system. During

experiments LP-SB-I and 2 the accumulators and LPIS were not

used and scaled HPIS flow was directed into the intact cold

leg. Volume scaling of the HPIS flow was based on the

assumption that only one of three charging pumps and one of

three HPIS pumps in the reference plant were available.

The LOFT steam generator located in the intact loop is a

vertical U-tube design steam generator. The use of auxiliary

feedwater flow to the steam generator during the experiment

reflected the initiation and employment of backup emergency

feedwater in a commercial PWR until the simulated depletion

of feedwater source (about 30 minutes).

In experiments LP-SB-I and 2 the breakline was connected

between the midplane of the hot leg and the blowdown

suppression tank.

An axonometric projection of the LOFT system configuration

for experiments LP-SB-I and LP-SB-2, and a LOFT piping

schematic with instrumentation are shown respectively in

Figures 1 and 2. More detailed information on the LOFT

system configuration is provided in Reference 1.

3 TRAC PFl/MODl MODEL OF LOFT FACILITY

Starting from the nodalisation used in the analyses of the

experiments LP-LB-I and LP-FP-l, an existing Atomic Energy

Establishment of Winfrith (AEEW) input deck was adapted to

reproduce the actual configuration of experiments LP-SB-l and

LP-SB-2 (Ref 2) these modifications were:-

Removal of the three-dimensional vessel and

implementation of a one-dimensional model.

AEEW - R 2202 2
Nodalisation of the broken loop.

Addition of pump injection.

Removal of accumulator and line.

Nodalisation of the hot leg break.

The final noding diagram is shown in Figure 3. The number of

components used to model the facility were 36, with 142 cells

and 42 junctions.

3.1 Reactor Vessel

After the initial consideration that in LP-SB-2 the

transient evolution in the vessel did not show strongly asymmetrical behaviour it was decided to take advantage of

the multistep numerics of TRAC-PF1/MOD1, which are restricted

to one-dimensional components, by changing to a

one-dimensional vessel.

The one-dimensional vessel geometry was developed by

transposing fluid volumes,.flow areas and cell lengths from

the three-dimensional vessel cell mesh of the LP-FP-1 deck,

and the results were cross checked with the LOFT reference

documentation.

The nature of the description, to TRAC, of heat structures

(specification of a pipe's internal radius and thickness)

prohibits the exact representation of the surface areas, and

volume and thickness of the vessel metalwork. Any two

parameters may be input precisely and some compromise between

all three may be used. The approach adopted here was to

concentrate on preserving the overall volumes and surface

areas of the metalwork. No representation of two sided heat

structures is available in the one or three dimensional

vessel, resulting in a further substantial limitation.

On the basis of steady state mode calculations, friction

factors were derived which enable reasonable agreement with

the available pressure drop data to be obtained. Five of six

core bypass paths were modelled (see Figure 4): Bypass Path

1 (lower core support structure bypass), Bypass Path 2 (lower

end box bypass) and Bypass Path 3 (gauge hole bypass) were

represented by the side arm of a TEE component (Figure 5).

Bypass Path 4 (outlet nozzle gap) was modelled as a PIPE.

Bypass Path 5 (core barrel alignment key) was represented by

a PIPE component between the two sections of the upper

plenum. It was not possible to model Bypass Path 6 (core

filler block gap) because the one-dimensional core component

is permitted to have only two junctions. The downcomer

bypass was also modelled.

AEEW - R 2202 3
3.2 Steam Generator and Steam Line

The steam generator consisted of a boiler, a separator and a

downcomer region. In order to adequately reproduce the

subcooled region of the boiler, the bottom cell of the boiler

was halved in length, as well as the corresponding primary

side cells. The steam separator was simply modelled by

imposing perfect separation at its top junction.

The overall heat losses were set to 21.4 Kw as the best fit

to the available data (Ref 3).

Heat structures in the steam generator were better

represented than in the vessel due to the capability of the

steam generator component to cope with two-sided and multiple

heat structures.

The friction loss in the junction between the downcomer and

the boiler was modified to fit the reported recirculation

ration 4.8. No steam bypass valve was modelled; its function

was taken over by the main steam control valve. A detailed

description of the modelling can be seen in Figure 6.

3.3 Intact and Broken Loops

The loss of coolant occurred through a break in the intact

loop hot legi therefore the hot leg representation in the

TRAC deck was modified to accommodate the break.

The length of the biqeat line was 5.61 m with flow arel

section of 6.82 10-4 m4 and a nozzle ?f 1.2668 10- m that

corresponds to a diameter of 1.27 10- m. The length of the

cell connecting to the nozzle was made equal to 0.1 m. The

HPIS discharged into the cold leg at an angle of 900 to the

mainline.

A characteristic of the LOFT facility is the existence 6f a

fluid path connection between both legs of the broken loop in

order to equalise the pressures between the upper core and

upper downcomer, making it easy to flood the core under

unexpected conditions. This bypass was supposed to be closed

during the experiment but a leakage of about 5.3% of the

circuit flow (480 kg/sec) passed through the reflood assist

bypass valves (Reference 3). In the nodalisation the flow

area of this junction was adjusted to obtain a flow rate in

reasonable agreement with the data.

4 EXPERIMENT LP-SB-2

Experiment LP-SB-2 addresses the analysis of a small break

loss of coolant accident with the break at the midplane of

the intact loop hot leg. In contrast with LP-SB-l the

primary coolant pumps were running for most of the experiment

until the trip set point on pressure was reached.

AEEW - R 2202 4
A detailed description of the experiments is found in

Reference 4.

4.1 Steady State Calculations

Starting with input conditions well away from the operating

steady state, 500 seconds of steady state calculations were

run to achieve a reasonable degree of convergence. During

this period the predominant timestep was 1 sec and the

(CPU/Problem) time was 0.36. In order to obtain a final

steady state a subsequent run of 70 secs with a maximum

timestep of 0.1 sec was performed; the (CPU/Problem) time was

2.0. The total (CPU/Problem) time ratio was 0.56.

To establish the required steady state a control system -was

implemented acting on the following variables:-

Steam generator mass balance

Downcomer liquid level

Secondary pressure

Primary system pump speed

A further description of the control system may be found in

References 5 and 6.

The model environmental heat losses from the primary side

were 224 Kw and 21.4 Kw from the steam generator in agreement

with Reference 3.

The percentage of the loop mass flow (480 Kg/s) diverted

through the different bypasses was the following:-

Component

79 Core Barrel Alignment Key 0.04%

83 Outlet Nozzle Gap 2.7%

85 Downcomer Bypass 20%

89 Core Bypass 3.5%

31 Reflood Assist Bypass Valve 5.3%

The obtained primary side initial mass was 5640 Kg. The

total deviation with the computed inventory for the LOFT

facility of around + 7.6%. A further study on the broken

loop structure allowed for a reduction of this offset up to a

+3.8%.

The steam generator secondary side water mass inventory

obtained for the steady state was 2089 Kg.

The steady state initial conditions obtained are shown in

Table 1.

AEEW - R 2202 5
4.2 Transient Boundary Conditions.

As far as possible all variables and parameters external to

the LP-SB-2 calculation were modelled using the actual

experimental data.

Among the most important parameters is the actual size of the

break, 1.27 cm in diameter. The subcooled and two phase

choked flow multipliers were 1.0 in value. The reactor power

decay heat was provided by the best estimate data provided in

Reference 7.

The pumps were kept on spinning at their steady state

velocity, 331.3 rad/sec (- 316 in experiment), throughout all

the transient until their trip set point was reached. No

heat source from pumps dissipation was provided, which is

thought not to have affected the overall evolution of the

calculation. The pumps injection flow was added immediately

downstream, each pump assuming a constant flow of 0.0475 1/s

The secondary side steam control valve, as previously

mentioned, assumed the function of the steam bypass valve.

Estimated pressure setpoints deduced from direct reading of

experimental data on pressure and valve movement governed its

behaviour in the transient. After 80 seconds it was latched

closed to a minimum flow area of 0.35% of its fully opened

value, throughout the transient. This figure, derived from

the LP-SB-3 EASR (Ref 8), implies a steam leakage of - 0.125

Kg s-1 at a secondary pressure of - 5.5 MPa.

The auxiliary feedwater flow was constant and its temperature

2090C.

4.3 Chronology of Events for Experiment LP-SB-2

The experiment started with the opening of the break valve in

the hot leg of the intact loop. After 1.8 secs the pressure

fell below the reactor scram set point value (14.28 MPa).

Simultaneously the main feedwater valve started to close and

with a one second delay the main steam control valve began to

close. At.4.3 seconds the main feedwater valve was isolated

and the main steam control valve was fully closed at 14.8

seconds, though a small leakage was assumed. As a

consequence of the subsequent pressure increase, the steam

bypass valve was actuated. Meanwhile at 42.4 seconds the

HPIS was initiated and at 50.2 seconds the subcooled blowdown

ended. At 63.8 seconds the steam generator auxiliary

feedwater was manually initiated. At 582.2 seconds the pumps

degradation was observed and at around 600 seconds the onset

of partial phase separation in the hot leg was detected. At

around 1200 seconds the break started to uncover so

increasing the depressurisation rate and after 1290 seconds

the secondary pressure exceeded the primary pressure. After

1864 seconds the auxiliary feedwater was shut off and at

AEEW - R 2202 6
- 2853 seconds both primary coolant pumps were tripped after

reaching their pressure set point (3.16 MPa in primary

system).

5 POST TEST CALCULATIONS

The results from two different runs are described in this

Section. The first one, called Run A, was the first attempt

to reproduce the experiment LP-SB-2 and no feature other than

those implemented in the current standard version of the code

(12.7) was used. Important conclusions were derived from

this run. To confirm these results a major modification in

the break line, together with a Winfrith implemented model,

were used to make a second run, called Run B; at the same

time other minor modifications were added to the input deck.

5.1 Run A

Operational set points and chronology of events are shown in

Tables 2 and 3 respectively.

5.1.1 Code Performance

The code speed can be clearly separated in three regions

(Figure 7). The first one comprises from 0.0 to 1000

seconds, the code is mostly using its maximum allowed

time step of 0.5 seconds (Figure 8) and the

(CPU/Problem) time is - 0.45. From 1000 seconds to 2650

seconds the code drops its speed and the average time

step is - 0.08 seconds. The (CPU/Problem) time is -

3.1. This change of behaviour is found to be related to

changes in flow directions in the broken loop and in

Pump No 1 (discussed later). From - 2650 up to the end

of the calculation the average time step recovers to -

0.4 and the (CPU/Problem) time is - 0.51. This recovery

of speed in the calculation is found after the pumps

trip. At 3000 secs the total number of time steps is -

25500 and the total (CPU/Problem) time is 1.95.

The SETS numerical method allows for the violation of

the material Courant limit. A Courant value of - 12 is

common in the cold leg during the fastest period of the

transient (4t = 0.5 sec). A Courant value of 1 would

imply At = 0.04. This capability to violate the Courant

limit allows the detailed modelling of bypass pathways

in the vessel.

5.1.2 Short Time Behaviour (0.0 - 850 sec)

The evolution of the main variables: pressure,

temperature and density is now described, finally the

fluid velocities and transient mass inventory will be

discussed.

AEEW - R 2202 7
5.1.2.1 Pressure Behaviour: Primary Side

Following the opening of the break valve a sudden

decrease of the pressure (Fig 9) is observed. This

period corresponding to the subcooled blowdown, is

adequately predicted by the code, reaching the scram set

point at 2.3 seconds. After - 53 seconds the fluid gets

into saturated conditions; as voidage develops, the

upper plenum of the vessel becomes vapour bound (Fig

10). The steam generation helps to stabilise the

pressure, which is well reproduced by the code.

Discrepancies in the break flow (Fig 11) may account for

the slight differences obtained between experimental and

calculated primary pressures.

The calculated pressure drop from the bottom of the loop

seal to the pumps inlet was about 75 Kpa at time 0.0

while the experiment indicates - 20 Kpa. The reason for

the discrepancy is the big pressure loss predicted by

TRAC at the symmetrically flow dividing tee. As the

overall system pressure loss is reasonably well

reproduced, the actual pump pressure increase should

remain unaffected. Having in mind this result the

pressure increase through Pump No 2 is compared with the

reading from PDE-PC-001 (Fig 12). It shows a bigger

sensitivity at low void fractions than the experiment

that is due to the selection of the head multipliers

(Appendix A). The overall result is considered to

reproduce the experimental result adequately. This

indicates that the combination of mass flow, pump speed

(constant), density and void fraction, together with the

pump head degradation multipliers and pump homologous

curves is consistent with the experiment.

5.1.2.2 Pressure Behaviour: Secondary Side

Simultaneously to the reactor scram, the main feedwater

valve starts to close, followed by the closure of the

steam control valve. As a consequence an increase of

the secondary side pressure (Fig 13) is observed. The

rate of pressurisation is overpredicted producing an

early activation of the steam bypass valve. This

overpressurisation was found to be dependent on steady

state initial pressure, mass distribution and timing for

the closure of main feedwater and steam valves. In any

case the pressure rise rate was above the experimental

one. Due to the secondary role played by the steam

generator this problem did not affect the results

seriously.

The energy removal from the steam generator was through

the steam valve leakage (0.125 kg/s at 5.5 MPa) and heat

losses through the shell. The combined effects of these

and the introduction of subcooled water via the

auxiliary feedwater dealt with the heat transferred from

AEEW - R 2202 8
the primary side and finally determined the secondary

side pressure.

5.1.2.3 Temperatures

As soon as the chain reaction ceases in the core the

main source of heat during the transient is the core

decay heat. The early slow decrease of the hot leg

liquid temperature during the subcooled blowdown (Fig

14) is associated with the rapid increase of the

pressure in the steam generator. On reaching saturation

the temperatures follow the same behaviour as the

pressures.

The temperature in the cold leg of the intact loop (Fig

15) rises during the first - 20 seconds due to the

decrease of AT through the steam generator. After the

opening of the steam bypass valve and up to its final

closing the temperature decreases as AT increases. In

the experiment this behaviour is not observed. The cold

leg temperature remains almost constant until the final

closure of the steam bypass valve, at which time it

rises and finally follows the presure trend.

During all the period studied the steam generator

behaves as a heat sink (Fig 16) due to the existence of

a small positive difference in the presures between

primary and secondary side. Most of the energy however,

is released through the break.

5.1.2.4 Density Distribution

In the experiment LP-SB-2 the distribution of the

densities is strongly affected by the running pumps. In

Figures 17 and 18 the hot leg and cold leg densities are

represented. The experimental measurements are related

to the absorption of three beams of gamma rays covering

the top, middle and bottom cross section of the hot and

cold leg specified locations (see Fig 19).

Early in the transient voidage started to develop in the

upper plenum of the vessel (- 46 sec), in the top of the

steam generator U-tubes and in the loop seal (- 60 sec),

Figures 10, 20 and 21. This voidage (SG and loop seal)

was strongly influenced by the secondary side behaviour

in the first seconds of the transient. As soon as the

heat transfer to the secondary side falls, the cold leg

temperature increases, and as the loop seal is the

minimum pressure location of the loop some voidage

occurs there. After 80 seconds the secondary side steam

bypass valve finally closes, thus increasing the

secondary side pressure and enhancing the voidage

generation. In the experiment this voidage is partially

collapsed in the cold leg, ie the cold leg density

decreases later than the density in the loop seal. This

AEEW - R 2202 9
was not observed in the calculation resulting in a lower

density than the experiment for a period of about

200 seconds. In general, though, the density in the

cold leg is reasonably well reproduced during this

period.

The calculated density in the hot leg in itially

increased because the more dense fluid overrode the

incipient voidage being transported from the vessel

during the first 100 seconds; from then on the density

decreased steadily. Early in the experiment (- 50 secs)

a more or less continuous density gradient develops in

the pipe and at around 600 seconds it turns into a steep

gradient indicating a probable flow transition. This

complicated pattern is not observed in the cold leg as

the mixing from the pumps tends to maintain an

homogenous void distribution in the cross section of the

pipe.

As is clear from Figure 22, a systematic overprediction

of the break line density was obtained; the calculated

density practically matches that of the average hot leg

while the experimental is almost that of the top beam in

hot leg. This vapour pull-through phenomenon is not

modelled in the code.

5.1.2.5 Fluid Velocities

LP-SB-2 experiment was characterised by the long time

both reactor coolant pumps were running. During the

period under study no cessation of loop forced flow

happened, therefore the fluid velocity in the loop was

closely related to the pumps performance. The reduction

in pump pressure rise implied a reduction in fluid

velocity; this trend was specially well reproduced in

the cold leg (Fig 23). The calculated velocity

reduction in the hot leg was analogous to the one in the

cold leg but it did not fit the experimental trend so

well (Fig 24). The fluid velocity in the downcomer had

an initial value lower than the experimental one, the

flow directed through the downcomer bypass could account

for most of this initial mismatch, Figure 25. The

constant decrease in velocity observed in the experiment

is not observed in the calculation. An asymmetrical

flow distribution in the downcomer annulus could explain

in some degree this discrepancy.

The calculated fluid velocities in the core inlet and

outlet were multiplied by 1.3 to account for the

difference in flow area in the measurements location

between the experiment and the calculation (Table 4);

with this correction the results obtained are shown in

Figures 26 and 27 respectively. The results obtained

before the pumps degraded show a better agreement than

after. The pumps degradation was not reproduced with

AEEW - R 2202 10
the sharpness of the experiment, correspondingly the

velocities did not fall so sharply.

The fluid velocity in the break line (Fig 28) is well

reproduced, with a small underprediction in the

subcooled region.

5.1.2.6 Transient Mass Inventory

To achieve a proper description of the actual mass

inventory detailed calculations of the inlet and outlet

flows are required. The fluid inlet sources to the

primary system were the pumps cooling injection and the

HPIS. During the period under study the mass loss

through the break was much bigger, being well within

LOCA conditions. In Figure 11 the break mass flow rate

is shown. As soon as the break opened, choked flow

conditions were detected. During the subcooled blowdown

the code subcooled choked flow model was invoked with a

multiplier factor of 1. The results show a slight

underprediction. The code two-phase model was invoked

with a multiplier factor of 1. For the very low quality

region a slight underprediction was observed. From 600

seconds on, a permanent overestimation of the break mass

flow rate is obtained. The evolution of the calculated

and experimental mass (obtained from the integrated flow

balance) can be seen in Figure 29.

5.1.3 Lon2 Time Behaviour (850 - 3000 Seconds)

5.1.3.1 Pressure Behaviour

The secondary side pressure decline appears to be

reasonably well reproduced indicating that leakage

through the steam valve is about correct (Fig 30).

After 1307 seconds the primary side pressure fell below

the secondary side. Thus the steam generator no longer

acted as a heat sink (Fig 31). At a 1864 seconds the

auxiliary feedwater to the steam generator was suppresed

and as a consequence the rate of depressurisation slowed

down. Unexpectedly the experimental trend is the

opposite.

In the primary side (Fig 32) a discrepancy with respect

to the experimental result arises from 800 seconds

onwards, the break uncovery which in the experiment

happened at about 1200 seconds was delayed in the

calculation up to 1900 seconds. The experimental break

uncovery appears to happen when the hot leg collapsed

level reaches the break level (Ref 9) while in the

calculation transition to steam flow corresponds to a

complete depletion of the hot leg. This depletion is

consequence of the loss of sufficient mass inventory

to eventually allow the vessel swell level to fall below

the nozzles at around 1920 secs. The hot leg was

AEEW - R 2202 11
emptied and consequently only steam was released through

the break with the subsequent increase in depressurisation rate. At around 2100 and 2660 seconds the

primary pressure curve shows the existence of two spikes

which correspond to the sudden transport of water to the

break line after a momentary increase in the swell

level in the core (first spike), and to the water

drained from the inlet plenum of the steam generator after the pumps trip for the second one.

The time at which the pumps were tripped (3.16 MPa in

primary side) was 200 seconds before that in the

experiment.

5.1.3.2 Temperatures

In the hot leg the fluid temperatures Figure 33 were at

saturated conditions and therefore followed the trend in

pressures. The situation in the cold leg was strongly

dependent on the distance from the HPIS injection

location. As can be seen in Figure 34 the difference

from saturation temperature 1.52 m before the HPIS

location was almost nil until the pumps were tripped,

after which part of the HPIS subcooled water was flowing back to the loop seal. In the experiment no sudden

decrease in temperature was observed because after the

pump trip the cold leg was partially flooded with water

coming from the vessel outweighing the cooling from the

HPIS.

The subcooling at the HPIS injection location and at the

cold leg nozzle (- 1.15 m from HPIS) started to be

noticeable after 1200 seconds, the inlet subcooling

(Tsat- Tli ) to the vessel was around 5 0

C up to - 1850

seconds, w•en the cold leg was depleted. At this time

the subcooling temperature in the cell where the HPIS

was discharging jumped to - 1200C and the subcooling at

the inlet nozzle of the vessel was around 100C. After

the pumps were tripped the non-uniformity was more

pronounced with a subcooling of - 170 0 C at the injection

point and a subcooling - 40°C at the inlet of the

vessel.

The fuel cladding temperature merely followed the trend

of the saturation temperature corresponding to the

existing pressure. After the pumps were tripped the

downcomer and core levels equalised and as a result the

top of the core slightly uncovered producing a

negligible excursion in the cladding temperature of

about 10°K (Fig'35) until the growth of the swell level

quenched the rod.

AEEW - R 2202 12
5.1.3.3 Density Distribution

The calculated hot leg density (Fig 36) shows an

evolution in reasonable agreement to the experiment up

to - 1500 seconds in which the calculated and

experimental trend noticeably starts to differ. In the

calculation no forced flow cessation is detected and at

- 1800 seconds the hot leg is completely depleted while

in the experiment forced flow cessation is observed

which results in a fall in the hot leg level but later

the level rises again. The explanation- given in

Reference 4 is the following: The level rise is...

"due to a coolant density decrease in the core as a

result of decreased fluid velocity and a liquid level

drop in the downcomer because the pump operation

pressurised the cold leg and upper part of the downcomer

relative to the upper plenum. The downcomer liquid

level also decreased due to the manometer effect between

the column of liquid in the downcomer and the column of

less dense coolant in the core and upper plenum". After

the pumps were tripped the consequent increase in the

core void fraction accounts for the observed rising in

level. This late rise in level was not observed in the

calculation due to the small inventory of water

remaining in the system which did not allow the core

swell level to reach the nozzles.

The calculated tendency in the cold leg (Fig 37) was

quite similar to that of the hot leg, reproducing the

phenomena observed in the hot leg. Note, though,

that after the pumps were tripped an increase in the

cold leg density was observed. This is due to the

growth of the layer of water coming from the HPIS which

at this time is no. longer dragged to the vessel by the

steam previously pumped from the pumps. At the same

time the density in the loop seal increased as the water

was running down to the bottom of the loop seal from the

cold leg. The experimental trend is markedly different

from that of the hot leg. First of all there was no

density gradient across the pipe until - 1200 seconds,

due to the mechanical mixing provided by the pumps. .As

soon as the forced flow ceased, around - 1500 seconds,

the fluid stratified. It is thought that after - 1200

seconds of transient the transport of liquid in the

upside of the U-tubes of the steam generator greatly

worsened due to the low velocity of the steam and to the

onset of clear stratification conditions througout the

hot leg. This produced a gradual depletion of the cold

leg with respect to the hot leg, and as a result the

level above the bottom of the pipe was considerably

lower than that of the hot leg. After the pumps trip a

jump in the cold leg density was observed. This was due

to the level increase in the downcomer that reached the

cold leg level allowing its flooding. Once the level

was enough to pass over the pumps outlet lip (- 10 cm

height) part of the liquid ran down to the loop seal.

AEEW - R 2202 13
In the nodalisation used this lip was not modelled,

therefore the flow to the cold leg was greatly

favoured.

The break flow density (Fig 38) was systematically

overpredicted until the hot leg pipe emptied. From then

on the density was correctly calculated.

5.1.3.4 Fluid Velocities

The liquid and vapour velocities in the downcomer (Fig

39) followed a quite different trend with one another.

To start with there is an initial slip induced by the

steam buoyancy. The liquid velocity shows an increasing

trend as the void fraction increases, as a result of the

liquid flow area reduction. At around 2000 seconds the

void fraction starts to decrease, reducing the liquid

velocity until it stagnates. The steam follows the

opposite trend, and after a further decrease in the pump

Ap at - 1200 seconds and the depletion of the broken

loop, it changes direction, and instead of flowing

towards the core through the lower plenum it rises,

going to the broken loop cold leg nozzle, towards the

broken loop hot leg via RABV.

The trend observed in the measurement from the

experiment is markedly different. The decrease in

velocity is sharper and at around 600 seconds the

velocity is extremely low. Meanwhile the velocity in

the core inlet, Figure 40, does not reproduce this

result, having at that time a high velocity. This

points to an asymmetrical distribution of the flow in

the downcomer, in which most of the flow is falling in a

fairly narrow section, centred on the cold leg nozzle.

This could be supported by the fact that the measurement

location in the downcomer is situated at - 1600 from the

cold leg nozzle. This suggests that the use of a threedimensional model of the vessel in a SBLOCA simulation

could be beneficial.

In the calculated core inlet velocities there is an

initial slip due to the positive effect of the buoyancy

of the steam bubbles. The liquid velocity reduces at a

lower rate than the experiment although the pumps Ap

(Fig 41) is well reproduced; at - 1200 seconds the

further decrease in the pumps pressure rise is followed

by a sharp reduction in the liquid and steam velocities.

Finally there is a residual liquid flow up to - 2000

seconds when the flow definitely stagnates.

The velocities in the core outlet (Fig 42) practically

follow the core inlet velocities. The evolution of the

liquid and steam velocities after the pumps trip reflect

the level drop in the core followed by the minor core

uncovery.

AEEW - R 2202 14
The hot leg velocities (Fig 43) are following the same

trend as the core velocities. Just after the sharp drop

in velocities after - 1200 seconds the code detects

stratified flow conditions, according to the Taitel

Dukler's criterion built into the code flow regime map.

From then on the liquid and steam velocity are less

strongly coupled and as a result the slip ratio

increases markedly. No cessation of the liquid flow is

calculated, stabilising at a velocity of around 1 m/s

when the bottom of the pipe fluid velocity detector

indicates stagnation. Along the top of the pipe the

steam is flowing toward the break and the steam

generator. Once the pumps are tripped a sharp decrease

in the velocities is detected and a residual steam flow

is maintained feeding the break. The liquid in the

upside of the steam generator is observed to begin to

drain towards the inlet plenum at around - 2000 secs

where it stagnates until the pumps are tripped. Then

the liquid is drained back to the hot leg.

The experimental and calculated cold leg velocities,

are very similar to those of the hot leg. The code

detected stratified conditions at about the same time

as in the hot leg independently of the strong mixing

produced by the pumps.

An important feature observed in'the calculation is the

asymmetrical further pump degradation observed at around

1200 secs. A sudden instability develops in which the

pump number 2 is delivering all the fluid, while through

pump 1 some fluid is being recirculated. As a result

the system velocities drop quite substantially. A

somewhat similar behaviour is reported in Reference 4

developing at the moment of the pumps degradation in the

experiment (582 secs).

The break line velocities (Fig 45) are well predicted

before the break uncovers - 1200 secs, at that time the

calculated density in the break line is much bigger than

in the experiment. At around - 2000 secs the code

detects the break uncovery and then the velocities are

again well predicted.

As a result of the reasonable representation of the

velocities and densities in the pipework the hot leg

mass flow rate (Fig 46) was in good agreement with the

experimental results up to - 1500 seconds.

5.1.3.5 Transient Mass Inventory

The permanent overestimation of the break mass flow rate

(Fig 47) produced a greater mass loss than in the

experiment. At around - 2000 secs the calculated rate

of mass loss equalised the inlet water from HPIS and

pumps cooling injection. In the experiment this time is

AEEW - R 2202 15
subject to a large uncertainty. A possible time at

which the LOCA was effectively terminated is - 2200

secs. The minimum inventory calculated was about 1100

Kg while in the experiment it was around 1800 Kg (Figure

48).

5.1.4 Conclusions Derived From Run A

a * TRAC PFI-MODl (12.7) provides a reasonably good

account of the evolution of the SB-2 transient.

b 0 The main discrepancy between the experiment and

calculation is the overprediction of mass loss

from the primary system.

c 0 The TRAC built-in flow regime map performs well

in identifying fully stratified conditions.

d 0 To improve the predictive capability of TRAC for

transients where phase separation upstream of

the break affects the break density, requires a

model relating quality in a branch to the

thermal hydraulic condition of the fluid in the

main pipe as well as considering the geometric

characteristics of the break line junction to

the main line.

e Prediction of the correct break flow should

reduce or remove discrepancies between the

experimental and calculated:-

- Primary Pressure

- Hot Leg Density

- Cold Leg Density

- Primary Mass

- Vessel Inventory and Subsequent Heat Up

f The use of a one-dimensional vessel did nbt

allow reproduction of an asymmetrical flow

distribution in the cross section of the

downcomer annulus and its influence in the

transient flow distribution through'the

bypasses, especially the RABV bypass.

g 0 SETS allow timesteps - 0.5 seconds to be used

for large parts of the calculation, and results

in relatively economical computing times.

5.2 Run B

In order to test the validity of Conclusion e derived from

AEEW - R 2202 16
Run A a second run was made. The main modifications with

respect to the input deck of Case A where:-

- Set up, using the TRAC control logic and two

offtakes, of a system which effectively could control

the quality in the break line as a function of the

void fraction in the hot leg.

- Modification of pump head multipliers to force a

sharp degradation at an inlet void fraction of - 0.35

and further modification of Pump No 1 head

multipliers in order to try to reproduce the

asymmetrical pump behaviour after degradation.

- Addition of a factor /% missing in the determination

of the critical gas velocity in the stratified model

(agreed from Los Alamos Reference 16).

The steady state conditions and chronology of events can be

seen in Tables 5 and 6 respectively.

5.2.1 Results Review

The control on the quality in the break line allowed the

reproduction of the experimental density with adequate

accuracy during all the transient (Fig 49). At the

moment at which the pumps were tripped the level in the

hot leg increased, allowing the discharge of a more

dense mixture. This transition was slightly accentuated

in the calculation although the final density at 3000

secs is correct.

The break mass flow rate (Fig 50) shows as expected a

much better agreement with the experiment than in Run A.

It is observed that the region from subcooled blowdown

to very low quality two phase shows a tendency to

underpredict the mass flow, and that at higher quantity

there is a tendency to overprediction.

The primary system mass inventory (Fig 51) agrees well

with the experiment, the minimum inventory is reached at

around - 1865 secs with a mass of about - 2060 Kg. In

the experiment the minimum inventory is reached after -

2200 secs with a minimum mass of about - 1800 Kg that

agrees well with the calculation [considering the

initial offset of - 250 kg]. The slight underprediction

of the break flow in the very high quality region

x ) 0.99 implies a faster mass inventory recovery than

in the experiment. The correct description of the break

flow as well as the appropriate heat losses results in

an excellent description of the primary pressure (Fig 52). The change in the depressurisation rate after

break uncovery is properly calculated. The secondary

side pressure (Fig 53) has improved as well, although

some discrepancies in the trend of depressurisation

AEEW - R 2202 17
appear after 1200 secs. Corresponding to the good

primary pressure calculated, the fluid temperatures are

very well reproduced. The liquid hot leg temperature is

shown in Figure 54. Similarly the cladding temperature,

Figure 55, in the core was correctly calculated; the

increase in temperature after the pumps trip was due to

the increase in pressure following the decrease in

volumetric flux through the break after the growth of

the hot leg liquid level.

The smaller amount of mass lost through the break

implied in general a higher density of the fluid

throughout the transient than in Run A. In Figure 56

the hot leg density is shown. The value obtained up to

- 1400 secs is reasonable while the evolution of the

density after that time, as no cessation of forced flow

was obtained, differs significantly from that of the

experiment and a constant value for the density,

corresponding to a normalized collapsed level above the

bottom of the pipe of - 0.3 was obtained. After the

pumps were tripped an increase in the hot leg density

was obtained due to the draining of water from the

upside of the steam generator, and the increase in the

swell level of the vessel which overrides the decrease in the collapsed level in the core. The computed cold

leg density (Fig 57) shows a similar behaviour 1:o that

of the hot leg before the pumps degrade. After the

subsequent sharp decrease in velocity a build up of

liquid with respect to the hot leg is calculated. The

failure of the code to predict the end of the forced

flow in the system prevents the pumps from emptying the

loop seal and cold leg, therefore the density calculated

from - 1400 secs on is considerably higher than that of

the experiment. Once the pumps are tripped the fluid in

the cold leg drains partly to the vessel and partly to

the loop seal producing a considerable reduction in the

cold leg density.

The transient fluid velocities in the system were

significantly affected by the modifications to the pumps

as well as by the higher densities calculated in Run B,

compared to Run A. The downcomer liquid velocity (Fig

58) is no longer steadily increasing as in Run A. At -

1200 secs the broken loop empties, establishing a new

flow distribution in which the steam content in the

downcomer rises and is diverted to the upper plenum via

the RABV (vapour velocity negative in Fig 58) while

practically only liquid is flowing to the core. This

strongly affected the density distribution in the core,

Figure 59, inducing a voidage decrease and a slight drop

in the swell level. The general trend of the core inlet

velocities is reasonably reproduced (Fig 60), although

the rate in decrease of the velocity is always

underestimated. At around 1300 secs the liquid and

steam velocities became stable and no cessation of the

AEEW - R 2202 18
forced loop flow is observed. The fluid velocities

calculated in the hot leg (Fig 61) did not reproduce the

permanent slowing down observed in the experiment. On

the contrary after the pumps degradation an almost

constant velocity is obtained. The reasonable

description of the pumps delta pressure (Fig 62), that

after degradation shows a weak dependency on the voidage

and volumetric flux, seems to eliminate its influence as

a main source of the problem unless the data is

significantly in error. Three factors could play an

important role in the explanation of the discrepancy in

the velocities. First of all there could be an

underprediction of the two-phase pressure losses in the

circuit. Secondly the considerable liquid mass flow

transported from the hot leg, under stratified

conditions, to the steam generator inlet plenum,

overcoming the upside bend section of the hot leg which

prevents the loop seal from being depeleted. Thirdly,

the phases separate in the downcomer inlet annulus, with

the steam being bypassed through the RABV line. If the

RABV leakage were smaller this would present a greater

resistance to the general loop circulation, in

particular reducing the steam velocity. As a result of

the poor prediction of the velocity the mass flow rate

in the hot leg was not properly reproduced after the

pumps degradation (Fig 63). The prediction for

stratified flow was acceptably performed in the code; at

around 700 secs (at a steam velocity slightly below the

experimental value of 1.5 m/s) transition to stratified

flow begins. At - 1150 secs the code computes pure

stratified flow that is in good agreement with the

experiment. (See Chapter 6).

Before the break uncovery the velocities in the break

line (Fig 64) showed a permanent overprediction while

after the uncovery, when practically only steam was

flowing, the velocities were underpredicted. As the

density in the break line was correctly reproduced a

possible explanation would lie in the velocity predicted

by the choked flow model.

5.2.2 Conclusions Derived from Run B

a The good reproduction of the break line density

notably improves the results for:-

- Primary Pressures and Temperatures

Primary Mass Inventory

Vessel Inventory (No Core Heat Up)

b The removal of a model deficiency in the

description of break flow allows a deeper insight

into the ability of TRAC-PFl/MODI in reproducing

AEEW - R 2202 19
phenomena which otherwise would have been masked,

eg loop flow velocities.

c Taitel and Dukler's criterion built into the code

performs well in determining fully stratified

conditions. The interpolating criteria used by

TRAC properly identifies the transition to

stratified flow, although at a lower steam velocity

than in the experiment.

d The pumps behaviour in LP-SB-2 experiment is

considered to have been only partially reproduced

and considerable uncertainties remain about the

true pump characteristics for the LOFT

configuration.

e The loop fluid velocities never dropped to almost

stagnation conditions in contrast to indications

from the experiment. It is possible that a better

prediction of two-phase pressure losses and liquid

transport from horizontal stratified conditions in

the hot leg toward the inlet plenum of the steam

generator, together with an accurate RABV bypass

flow may help to remove the discrepancies.

6 SELECTED ITEMS

6A LP-SB-2 Pumps Modelling

The experiment LP-SB-2 was characterised by the important

role played by the primary coolant pumps. They were a main

factor in explaining many of the features observed in the

experiment: density distribution, RABV and vessel flows, and

flow regimes.

The uncertainty involved in the description of the two-phase

performance of the pumps has been regarded as a limiting

factor in the capability to reproduce the experiment (Ref 9).

The intact 1 oop of the facility contains two similar pumps

working in parallel. The strong coupling between both pumps

constitutes a potential source of instability as soon as

asymmetrical perturbations in the flow conditions affect the

pumps inlet.

The assumption of similar behaviour of both pumps could not

be sustained as the actual trend observed .in the experiment

pointed to a clearly asymmetrical one (Ref 4). Thus in order

to create an adequate set of head multipliers it would have

been desirable to know the individual fluid conditions and

performance for each pump; unfortunately that was not the

situation and the available data only provides an average

description.

In experiment LP-SB-2 the density measurement in the vertical

section connecting the steam generator with the bottom of the

AEEW - R 2202 20
loop seal (DE-PC-003B) was questioned in Reference 4 as

unreliable, thus an adjusted density was used to derive the

pump head versus pump void fraction. (Figures Al, A2 and A3

taken from Reference 4). With the adjustment it was found

that the SB2 pump head closely matched that of L3-6

experiment. Under this assumption a set of two phase head

multipliers was derived from Reference 11, and they are shown

in Table Al; to be consistent with the procedure to obtain

the head multipliers, the TRAC LOFT pump data for the first

quadrant of the fully degraded characteristic curve was set

equal to zero.

The head versus pump void fraction calculated in Run A for

both pumps is plotted in Figure A4. It is observed that

although the head multipliers derived from L3-6 have been

used, the results for a void fraction below 0.4, lay between

the unadjusted head for SB-2 and the L3-6 head (Fig A2).

This discrepancy could be partly related to the uncertainty

of the data used to derive the head multipliers for low

voidage and possibly to the mass flow dependence of the head

multipliers, which is not included in the TRAC model for the

PUMP component. On the other hand the coincidence, between

the calculated and measured density in the loop seal (Fig A5)

up to 500 seconds points to a questioning of the trend for

the adjusted density at low voidage, which would suggest that

the unadjusted head could be correct at least up to a voidage

of - 0.4.

A better description of the degradation could be obtained

with-the available data used to derive the general set of

head multipliers.

At the moment of the degradation - 580 secs a perturbation

related to the individual behaviour of both pumps was

observed in the calculation (Fig A6); after a few seconds the

behaviour stabilised again until at around 900 secs

(a - 0.55) the behaviour of both pumps started to differ and

very quickly the direction of the flow within the pumps loop

was such that all the mixture was pumped by Pump 2, Figure

A7. In Pump 1 the situation was very different; the void

fraction at its inlet rose to practically 1 and a flow of

about 5 Kg/sec was recirculated from Pump 2.

The mechanism driving this behaviour was found to be related

to the slight asymmetry of the pumps layout which implied

that the fluid velocities through both pumps were slightly

different. This in turn implied that the void fraction at

the inlet of both pumps were not the same and as a

consequence the heads through the pumps were not equal. This

mode of degradation was found to be strongly sensitive to

variation in the pumps characteristic curves and multipliers;

by varying them the time of divergence could be drastically

changed, or the behaviour could be completely suppressed.

AEEW - R 2202 21
The consequences of this asymmetrical degradation were

important as the fall in the pressure increase provided by

the pumps implied a sudden drop in the loop velocities (Fig

43) and the. onset of counter-current flow in the downcomer of

the vessel (Fig 39). A somewhat.similar asymmetrical.

degradation was reported in Reference 4 to happen in the SB-2

experiment at the moment of the pumps two-phase performance

degradation. In order to try to reproduce this experimental

trend in RUN B the pump head multipliers were modified as

shown in Table A2; it is observed that the head multipliers

differ from one pump to the other after degradation, this in

fact constitutes a coarse approximation but allows us to

induce the asymmetrical behaviour to happen at the moment of

the degradation as it actually happened in the experiment.

An indication of the ability to reproduce these results may

be compared in Figures A8 and A9 (no possible quantitative

comparison is available as the motor and pump efficiencies

are not known for SB-2). At the moment of the degradation

Pump 2 takes over the delivery of the fluid mixture, thus

increasing the hydraulic torque while through Pump 1 some

fluid is being recirculated from Pump 2. The mass flow for

each pump are shown in Figure A10, where the sudden reduction

in the loop mass flow is evident; this in fact happens to be

too large at this stage if we compare with the experimental

result, Figure 63, which suggests that the degradation has

not been accurately reproduced and therefore a better set of

head multipliers would be desirable.

6B Break Flow Density in Experiment SB-2

The ability to reproduce the flow through the break line in a

small break LOCA scenario constitutes an important, if not

the main, factor in performing a satisfactory best estimate

calculation.

The problem of predicting the correct break flow can be

divided into two parts, first obtaining the corrrect mixture

density of the fluid convected from the main pipe to the

break line and secondly predicting the liquid and steam

velocities at the break nozzle under choked flow conditions.

This section deals with the first of these two elements.

In experiment SB-2 the observed density in the break line

strongly differed from the average of the density in the hotý

leg; being biased towards the density at the top of the hot,

leg pipe (Fig Bi). The pressure drop from the hot leg to the

break line was not large enough to explain the observed

difference between the average density in the hot leg and the

break line in terms of flashing so it should be related to

the phenomenon of vapour pull-through.

To reproduce this behaviour has been a common problem for

different organisations and codes including TRAC-PFl-MODI

(see Fig 38) trying to reproduce the LP-SB-2 experiment, eg

AEEW - R 2202 22
References 9, 10, 12, and at the present time it remains as

an open problem.

No information has been found covering the characteristics of

the experiment SB-2, that is: liquid and steam velocities in

the main pipe up to 8m/sec and flow conditions from bubbly

with high density gradient in the cross section to stratified

flow with steam at the top of the pipe and nonhomogenous

two-phase in the bottom of the pipe. The available

information covered purely stratified flow with stagnant or

very small velocities in the liquid, eg References 13 and

14.

From Reference 13 a correlation of the type:-

XBNCH = EXP x

h = collapsed liquid height in hot leg

was attempted, where the height for the onset of entrained

fluid hA is obtained from:-

/__.20.2

I C I gP Branchpg0)

D D g2 (PI -

and analogously the height for the onset of vapour pull

through hg :-

h. 1 C 1' 2 \.2

+ 1mBranch n. +D g (PI,- Pg)

where Cx, CA and C were constants to be obtained, 1 and mx

are the gas and liquid mass flux respectively, D is &he main

pipe diameter. The results obtained were unsatisfactory due

to the uncertainty in determining the mentioned constants and

the inability to find a single correlation applicable to all

the transient, in particular it was difficult to reproduce

the transition between the steady drop in density up to 1100

seconds and the quite sharp decrease as the break uncovers

(1100 - 1300 secs).

An alternative approach was finally adopted and the quality

in the break line was correlated to the void fraction in the

hot leg in the form of a table of pairs (a, x), see Table B1,

being used in conjunction with the Winfrith offtake model

(Ref 15). This of course implied that it would be only

applicable to the SB-2 experiment thus losing the generality

of a proper correlation. The values for the void fraction in

AEEW - R 2202 23
the hot leg were deduced from Reference 9, although for

a > 0.4 the correlated quality had to be slightly re-adjusted

in an iterative fashion to reproduce the experimental timing.

To implement this correlation the hot leg noding was modified

as seen in Fig B2. An extra offtake attached to the hot leg

was added and invoking a pure separator model would guarantee

a source of pure steam from the hot leg which would be

discharged to the break line. The flow of steam delivered to

the break line was controlled by the so called "control

quality valve". The scheme of the control logic is provided

in Figure B.3. At the same time the original offtake from

the hot leg makes use of the Winfrith offtake model for a

horizontal offtake when the level of the stratified fluid

drops below a determined value. This way of implementation

has the advantage of allowing the testing of different

correlations in a straight forward way, eliminating the

problems involved in modifying the cell edge quality within

the TRAC code.

The results obtained with this procedure can be seen in

Figure 49.

6C Flow Regimes Prediction for LP-SB-2

From the point of view of the analysis of flow regimes, the

experiment LP-SB-2 constitutes an interesting example of the

important role the exact nature of the flow can play during

the evolution of a transient. In LP-SB-2 the break flow was

strongly determined by the flow conditions in the hot leg.

The existence of density data at different elevations in the

hot and cold leg allows us to obtain at least an idea of the

complexity of the flow patterns during the transient. As can

be seen in Figure 56, early in the transient (- 200 secs) the

outputs from the gamma densitometers indicate the onset of a

density gradient across the pipe with trailing bubbles in the

upper section of the pipe. After the pumps degradation and

up to - 1200 secs the reduction in fluid velocity allows the

steam to concentrate in the upper half .of the pipe and as a

result the density gradient noticeably steepened. The

possibility of stratification in the sense of pure steam in

the very top of the pipe could be considered but the idea of

a well defined level cannot be supported as the density

reading in the top of the pipe indicates the presence of

liquid while the other two measurements indicate the presence

of steam. From 1200 seconds on, the top beam is indicating

only the presence of steam; from Reference 9 and according to

the trend of the collapsed and swell levels the flow was

stratified up to 1400 secs, stratified with bubbles up to

2000 secs and from then on pure stratified again. In the cold

leg, Figure 57, there is no detachment between the

densitometer readings up to 1200 secs which is due to the

transport of the mixing created by the pumps. From 1200 secs

up to 1500 secs a density gradient is present in the cross

section of the pipe, from 1500 secs up to 2000 secs the noisy

AEEW - R 2202 24
reading from the densitometers could indicate the presence of

erratic waves probably caused by fluctuations in the flow

delivered from the pumps as the loop seal is being depleted.

Despite this the flow regime may be considered as stratified

throughout the rest of the transient.

The recognition by TRAC of some of the flow patterns involved

in the transient is difficult especially when they involve

non fully developed regimes, ie partially stratified flow in

which the separation of the liquid and steam phases is far

from complete. The TRAC flow regime map from Reference 5 is

shown in Figure Cl plotted as log (FROUDE) vs vapour void

fraction. Included on the map is the TRAC implementation of

Taitel-Dukler stratified flow criterion and the limit for

interpolation for transitions into stratified flow.

The prediction for Run B can be considered satisfactory as

the code is able to predict the trend of the experiment

fairly well. Up to - 500 secs, see Figure C2, only bubbly

flow is predicted. From 500 secs up to - 700 secs some

weighting with slug is made. At 700 seconds the

interpolating criterion for stratified flow is reached.

Finally at around 1150 secs pure stratified flow is

predicted, this being the flow regime for the rest of the

transient. For the cold leg the results obtained indicated

transition to fully stratified conditions at about the same

'time as that in the hot leg, that is - 1100 secs; this is not

the trend of the experimental measurement which by that time

indicated the onset of a vertical density gradient. This

discrepancy is mainly dependent on the high degree of

mechanical mixing in the fluid induced by the rotating pumps

being transported along the cold leg. This effect should be

taken into account as the flow through a break in the cold

leg would be dependent on the fluid characteristics in the

main pipe and in particular the void profile at the break

line offtake location. It should also be noted that for Run

B a missing factor. /x in the determination of gas critical

velocity in the Taitel Dukler Test was implemented as agreed

from Los Alamos, Reference 16.

7 SUMMARY AND FINAL CONCLUSIONS

0 Two calculations of LOFT test LP-SB-2 were carried

out with TRAC PFl/MODl (approximately Version 12.7).

0 A one-dimensional description of the vessel was

implemented in the input deck. Due to the relative

importance of the different core bypasses, especially

the RABV, it would be desirable to use a 3-D

representation of the vessel in order to assess the

degree the prediction of the transient evolution is

affected. It would also help to evaluate the

possibility of asymmetrical flow distribution in the

downcomer annulus.

AEEW - R 2202 25
" The representation of the vessel, whether one- or

three- dimensional, has the limitation of the poor

description for heat structures. No double sided

heat structure is available and thus the radial heat

flux across all the vessel structures is only

partially reproduced. At the present time it is an

important limitation in the TRAC PFl/MODl modelling

of the vessel and a better description would be

desirable.

" The Code (CPU/Problem) time for Run A was considered

good, having a value - 1.95. In Run B this ratio

increased to - 2.3.

" The use of large timesteps was found as a possible

source of running problems as the code sometimes

failed when trying to reduce the timestep from big

timestep values. This meant that the maximum time

step had to be reduced in Run B during parts of the

transient.

* The set of initial conditions obtained for the steady

state in Run A and B were reasonably good. No

special problem was found in obtaining these steady

states.

• The chronology of events for Run A and B matched the

experiment in some degree. Not surprisingly, when

the break flow is well reproduced (Run B) the code

overall reproduces of the experiment results better.

* Vapour pull through and liquid entrainment were

observed to occur at the offtake of the break line.

TRAC PFl/MODl was unable to recognise this phenomenon

as no relevant model is actually implemented relating

quality in a branch to the thermal hydraulic

conditions of the fluid in the main pipe, as well as

considering the geometric characteristics of the

break line junction to the main line.

" The TRAC built-in flow regime map performs well in

identifying fully stratified &onditions in the hot

leg. The introduction of a missing factor Vu

(modification agreed by LANL) in the determination of

the gas critical velocity (performed in Run B) helps

to improve the results and the code is able to

predict the initiation of the transition to

stratified flow at about the correct time, although

the steam velocity at that time is underestimated.

" The calculated flow transitions predicted for the

cold leg closely match in time those of the hot leg.

The experiment shows that the high mixing provoked by

the pumps maintains bubbly conditions for a long

period. This generation of mechanical mixing, its

AEEW - R 2202 26
transport and then its influence on the flow regime

map should be considered for small breaks located in

the cold leg. The break flow will still-be a

function of the void profile in the cold leg, but

this is likely to be quite different from that in a

fully developed flow.

* The reproduction of the pumps behaviour in LP-SB-2

constitutes an important problem and no satisfactory

solution has been found yet. The pump model could

not be appropriately validated as the set of head

multipliers was not completely reliable, because it

was deduced under the assumptions of pumps average

behaviour and similitude to L3-6 experiment. Further

uncertainties were involved in the reproduction of

the asymmetrical pumps degradation, ie pumps inlet

flow condition.

It seems likely that in order to reproduce the

observed behaviour a priori, more sophisticated models of the pumps themselves, and of the effect of

the pump inlet branching geometry on inlet

conditions, would be needed than TRAC currently

provides. Better data from the test, however, would

probably allow an improved (a posteriori) fit within

the scope of the existing models.

* The velocities predicted by the code after the pumps

degradation were not entirely satisfactory and the

steady fall in velocity observed in the experiment

was not reproduced. Finally no liquid flow cessation

was calculated. Three possible causes may be

mentioned: underprediction of two-phase pressure

losses, handling of the liquid convected from the hot

leg towards the steam generator inlet plenum under

stratified conditions, and influence of the flow

through the RABV.

* The choked flow model predicted the results with

reasonable accuracy and the subcooled and two-phase

multipliers used for all the calculations were 1.0.

Small discrepancies in the velocities were observed

when the break line density was correct (RUNB).

* The mass loss predicted for Run A was large enough to

provoke a mild uncovery of the top of the core after

the pumps trip, contrary to experiment. In Run B

the break flow was adequately predicted and the mass

loss closely matched the experimental result. No

core uncovery was predicted.

AEEW - R 2202 27
REFERENCES

AEEW - R 2202 28
REFERENCES

1 READER, D L. "LOFT System and Test Description."

NUREG/CR-0247, Tree-1208.

2 ALLEN, E J. Internal Document.

3 BIRCHLEY, J. Private Communication.

4 MODRO, S M et al. "Experiment Analysis and Summary

Report on OECD LOFT Nuclear Experiments LP-SB-l and

LP-SB-2. OECD-LOFT-T-3205, May 1984.

5 LILES, R et al. "TRAC PF1/MOD1 and Advanced

Best-Estimate Computer Program for Pressurised Water

Reactor Thermal-Hydraulics Analysis". NUREG CR/3858,

July 1986.

6 PELAYO, F. Internal Document

7 McPHERSON, G D. "Decay Heat Data for OECD LOFT

Experiments". USDOE, October 1985.

8 ALEMBERTI, PROTO. "Experiment Analysis and Summary

Report on OECD LOFT Nuclear Experiment LP-SB-3."

December 1985, Draft (T-20000-XX-140-020).

9 ANODA, Y. "OECD LOFT Experiment LP-SB-l and LP-SB-2

Calculation Comparison Report." July 1986, Draft.

Japan Atomic Energy Research Institute.

10 POINTER, W. "Post-Test Calculation of the OECD LOFT

Experiment LP-SB-2 with DRUFAN-02." OECD-LOFT-T-3307,

December 1984.

11 TIEN-HU CHEN, SLAVOMIR, M MODRO. "Transient Two-Phase

Performance of LOFT Reactor Coolant Pumps". ASME Winter

Annual Meeting, 13-18 November, 1983. EGG-Nl-21982,

12 WESTACOTT, J L, PETERSON, G E & CHEXAL, U K. "Retran 03

Analysis of LOFT Experiments LP-SB-1 and LP-SB-2." EPRI

NP-4799 P Project 2420 Final Report, September 1986.

13 ANDERSON, J L & BENEDETTI, R L. "Critical Flow Through

Small Pipe Breaks." EPRI NP-4532, Project 2299-2 Final

Report, May 1986.

AEEW - R 2202 29
14 SCHROCK, V E. "Critical Flow Through a Small Pipe Break

on a Large Pipe with Stratified Flow." Presented at the

13th Water Reactor Safety Meeting, Gaitersburg, October

1985.

15 RICHARDS, C. Internal Document.

16 Letter from Los Alamos, R Jenks to C G Richards,

14 January 1987.

AEEW - R 2202 30
FIGURES

AEEW - R 2202 32

Intact IOOD Broken loop Intact loonBrenlo

14 BL- Quick opening experimental valve (2)

measurement

~~PC-2 (

0 experimental

o measurement

station

Steam

generator Isolation valve (2)

Prssrie BL-2 experimental

measurement •• station

densitometer .. o -ECC cold leg

*" "--'. Injection location

-PC-1

experimental

Drag disc measurement

and turbine

Break plane veseReactor -"

• Suppression

vessel DowncomerCoreCV-P139-57 /Lower plenunr

CV-P139-58 To BST

INEL.LP.SB.11LP.SB.2 1509

Axonometrlc projection of the LOFT system configuration for

Experiments'LP-SB-1. and LP-SB-2. From Reference 4
Swessed .010. - -U-st 11"o-&I I ~

tRi

N)

NJ

0

N)

sotP., ism .110J-is I -1'

Aw..bow. so

h door Posw-y COOIm' TI P139. PI L1PfP3.1

TE601,ATE-3O-1.IA *mow.. I I.P1394?. 1.2.3 32.33.34 T-1.1

141 14 0 #"&twoto I @ot4.w U.do.a

3 is.& 1w,14 P1o PC WE4I

10".S9Co.1 PC- Pow.O.Sp.f o~

lo odPloacn

3A.S.C. WhoCamIAmSrC.an9a

Plot~ ~ ol.1M1seti1 ~~~~ - e-OlPs 

DAD~~ PC.?Plses"

eleeclM 30 

14 bypass syss..

3PC -4

4w~ .fP" Ite PC... IA.... to Wattz loo

P T. PP'M3 - I t 114.s-C

I

L. J1 11 C~o.os .es loe. tF15 $##at

-I- Poe da.8el.ft on elect.. 3104 f.chae.e -A- Closo.".. lot.

D Re4octe

IreL t UCL-200M

2 LOFT piping schematic with Instrwoputation. From Reference 4
tzj Z.3

93..

to S/l/

3.

3 LOFT FACILITY NODING DIAGRAM
Key

4 CORE BYPASS FLOW PATHS

AEEW - R 2202 36
0 C.O ~hoUsAI Nes.

0 Pet. .CS

C.MFON~CNT Iq

(avIcPYNT S

cctmpciJ0Vr at*

5~bt~i. ~

LL~r PW~n~ (~c~r~ccrrQr)

~Aj~por *~iQA&h~~v% (C.a~it.)

P~QJ~LLa~ C~pa~ ~I¶Qr)

~jpc~.S 'Po*)'~. V

~ Cc~po~ ~)

con .poh wr Im L Lb(,.A% 0 c c tC.Cnm WI CRo

5 ONE-DIMENSIONAL VESSEL REPRESENTATION

AEEW - R 2202 37
6 STEAM GENERATOR NODING

AEEW - R 2202 38
THE FOLLOVING'ARE PLOTTED AGAINST REACTOR TIME

TOTAL TIME STEPS

Winfr Ithl

ti

KEY

SYR BOt NAME UNITS

- TOTAL TIME STEPS ,

LOCw o/ o/ I Hltr-STPT NF 3

,I ITRAC

0 500 1000

REACTOR TIME

1500 2000

SECONDS

2500 3000

7 TOTAL TIME STEPS

LP-5B-2 - TRAC PF1-MOOI AND EXPERIMENT COMPARISON
tI~

1'.)

t~J

.0

'U

0

TH1E FOLLOWING ARE PLOTTED AGAINST REACTOR TIME

TIME STEP SIZE

WiInfr' I thl

KEY

SYt NAME UNITS. BOL

- Ti7E SIEP SIZE " SECONOS

LOC= 0/ 0/ 1 INEtMzSEP IWf=l

TRAC

(n

03

z

0

u- wa

En

REACTOR TIMSE , SECONDS

8 TIME-STEP SIZE

LP-SB-2 - IRAC PF1-MOD1 AND EXPERIMENT COMPARISON
N

N

I~s,

0

I-.

THE FOLLOVING ARE PLOTTED AGAINST REACTOR TIMlE

SIGNAL VAR. NO. 2,PE-PC-002

WIlnfr Ithl

KEY

sYt NAME UNITS BOL

SIGNAL VAR. NO. 2,

LOC= 0/ 0/ 1 i1HEHl=S 2 INF-I

- - PE-PC-002 fH*

LOC. 77/ 0/ 0 I1NEHl-PRES INF-2

0. 20E

0. 18E

TRAC

0. 16E

EXPT

0. 14E

0. 12E

0. 1OE

0. 8OE

0. 60E

0. 40E

0. 20E

0. OOE

20

18

16

14

12

10

8

6

4

2

0

(3.

0 100 200 300 400 500 600

REACTOR TIME , SECONDS

9 INTACT LOOP HOT LEG PRESSURE

LP-SB-2 - TRAC PFI-MOOI AND EXPERIMENT COMPARISON

700 800
I lIE rIj.1LOVING ARE PLO1 £l AIAIIH;I IN At.1110 It 111

VAPOR FRACTIroN

1WInfrith

0

t,

KEY

SYII NAMIE UNIIS

DO.

1.0

- VAPOR FRACI ION

LtJC= 81/ 0/ 1 flNMflV0ID tVI

-N=ITRAC 0.8 --- VAPOR FRACTION 8

LOC- 84/ 0/ I 14NEI-VOID INE=I I

Vessel upper

plenum

Box before hot

leg nozzles

0.6

0.4

0.2

0.0

It

REACTOR 1I11E , SECONDS

!

D

t

10 VOID FRACTION IN THE UPPER PLENUM AND BOX

LP-SB-2 - TRAC PFl-MODl

BEFORE HOT LEG NOZZLES
THE FOLLOWING ARE PLOTTED AG61NST REACTOR TIME

toJ

0

MASS FLOW RATE ,FR-PC-S03

1WInfri th

KEY

SYM NAME UNITS

80L

- MASS FLOV RATE ,KG/SEC

L0•: 98/ 0/ 1 MNEM:FLOV INF=l

- - FR-PC-S03 ,KG/SEC

LOC- 23/ 0/ 0 MNEM-FLOV INW-2

14

TRAC

EXPT

U

Ilz

Ci]

w_

vr

0 100 200 300 400 500 600 700 *800

REACTOR TIME , SECONDS

11 BREAK MA'SS FLOWI RATE

LP-SB-2 - TRAC PF1-MOOI AND EXPERIMENT COMPARISON
:to

K)

J.s~

[liE FOLLOWING ARE PLOTTED AGAINST REACTOR TIME

PUMP DELTA-P *PDE-PC-O01

WInfri ,h

cAAnn•

JLJ~JI.JUU r -rKEY

sYti NAME UNITS 450000 BOL

- PUtl OELTA-P ,Nlnf..2 TRAC

LOC= 4/ 0/ 1 hiNEfDELP rWNI 400000

-- POE-PC-O01 ,KPA EXPT

LOC- 65/ 0/ 0 IINEM.PO INF.2 350000

300000

250000

200000 r

z 150000

100000

50000

A

W g I S I I

VA

lz,ý

\A

VIII'it

500

450

400

350

300

250

200

150

100

5O

0

-50

-100

0Lv<

v I I I J

-50000

_Ii n nn ý -- uJ

0 100 200 300

REACTOR TIME

400 500 600

, SECONDS

700 800

12 PRESSURE DIFFERENCE OVER TH-E MAIN COOLANT PUMPS.

LP-SB-2 - TRAC PF1-MODI AND EXPERIMENT COMPARISON
THE FOLLOWING ARE PLOTTED AGAINST REACTOR TIME

t~)

0

ul

SIGNAL VAR. NO. 6, PT-P004-01 A

JWInfrithJh

KEY

SYMi NAME UNITS

BOL

- SIGNAL VAR. NO. 6,

LOC= 0/ 0/ 1 iNEM=S 6 INF=I

7000000

00RAC

6500000

I I I I I . I ~ I I 7.0

I -5-

--- PT-PO04-OIOA ,IPA EXPT

LOC- 86/ 0/ 0 tKNEMPRES INF.2.

6000000

5500000

6.5

6.0

5.5

0<

50000001-

4500000

5.0

4.5

4.0 , nr.r.r.rar.

13 

SECONDARY 

SIDE 

PRESSURE.

LP-SB-2 - TRAC PFI-HODI 

AND EXPERIMENT 

COMPARISON 0 '100 200 300 400 500 600 700 800

REACTOR TIME , SECONDS

13 SECONDARY SIDE PRESSURE.

LP-SB-2 - TRAC PFI-MOO1 AND EXPERIMENT COMPARISON
T14E FOLLOVING ARE PLOTTED AGAINST REACTOR TIMlE

LIOUID TEtMPERATURE ,TE-PC-002B

lWinfr-I R

MI

0N,

KEY

SYi NAIME UNITS

BOL

- LIUI0 TOIiPERATURE *OEG.K

L0C= 99/ 0/ 2 IiNEtl=IEIL ITIW=

- - TE-PC-002B D 0EG. K

LOC. 130/ 0/ 0 IINEM-IIICL INf-2

rRI~c

EXPT

ILi

0 100 200 300 400 500 600 700 800

%!

l

i

!

!

REACTOR TIME SECONDS

14 LIO TEMPERATURE IN THE HOT. LEG OF THE INTACT LOOP

LP-SB-2 - TRAC PFI-MOO1 AND EXPERIMENT COMPARISON
THE FOLLOWING ARE'PLOTTED AGAINST REACTOR TIME

LIOUID TEMPERATURE ,TE-PC-0018

I In fr It hF

0

-J

I KEY

I n NAIE UNlITS

-LIUJIO TEMPERATURE ,DEG.K

SLICu 7/ 0/ 4 IIUEMMEIL INF-t

600 J |

PA~C

E XPT

5801-

-- 7E-PC-001B , DEG.

-LIC- 121/ 0/ 0 WJKfl.7fCL flF.2

560 . r . --- -- -- ------- o• ....

5401-

ti

0

5201.

5004-

4801

460 I

I I I I I S I I

0 100 200 300 400 500 600 700 800

REACTOR TIME , SECONDS

15 LIO TEMPERATURE IN THE COLD LEG OF THE INTACT LOOP

LP-S5-2 - TRAC PFI-MOOI AND EXPER9MENT COMPARISON
THE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME

SIGNAL VAR. NO.. 2,SIGNAL VAR. NO. 6

WUJin fr Ith

*N)

N)

0

N)

KEY

5Yt BOL NAME UNITS

SIGNAL VAR. NO. 2,

LOC. O/ 0/ 1 iINEM=S 2 IIF=I

--- SIGNAL VAR. NO. 6,

LOC. 0/ 0/ 1 WINEII-S 6 1NFWI

0. 20E

0. 18E I

TRAC

0. 16E

XPT

0. 14E

0. 12E

0. IOE

o. 8OE

0. 60E

0. 40E

0. 20E

0. ODE

0 100 200 300 400 500 600

REACTOR TIME * SECONDS

16 PRIMARY AND SECONDARY PRESSURES IN TRAC

LP-SB-2 - TRAC PFI-MOOI AND EXPERIMENT COMPARISON

700 800
THE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME UJInfrIth

0

1~i

MIXTURE DENSITY

DE-PC-O02C

,OE-PC-002A ,DE-PC-002B

KEY

STh NAME UNIITS BOL

- MIiXTRtE DENSITY ,KG/tl**3

LOC:: 991 0/ 2 tlNEfl=DENM INF..I

- - DE-PC-0O2Ak MlG/M**.3

LDC- 8/ 0/ 0 flNEM-.!ENM INF-2

---DE-PC-0028 M IG/M*#.3

LIJC. V/ 0/ 0 ttflEfl=ONMINFL.2

- DE-PC-002C II1G/ti*#S

LOC= ID/ 0/ 0 tiNEM1DflNt INFs2

TRAC

EXPT

BOTTOM

MIDDLE

TOP

1.0

0.8

0.6

N')

0.4 V

r

0.2

0.0

-0.2

REACTOR TIME

17 DENSITY IN THE HOT LEG INTACT LOOP

LP-SB-2 - TRAC PFI-MODI AND EXPERIMENT

, SECONDS

COMPARISON
TIHE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME 1WI n fr I t h1

N,

N)

0

N,

U'

0

MIXTURE DENSITY

DE-PC-O01C

,DE-PC-OOIA ,DE-PC-.OOIB

KEY

SYti NAMIE UNITS 001

- flIXTZ*RE DENS17Y ,KGIHl.3

LOC= 7/ 0/ 4 IiNEMIDENM l Iaf

1000

800

I I I I . I I

rRAC

- - BE-PC-00IA ,IG/tU__3 rXPT

LOC- 5/ 0/ 0 flNEMl=ENH IWV.2 IBOTTOM

--- B-PC-00IB tlG/l.P* iMIDDLE

LOC- 61 0/ 0 flNHE~.DENfl hV=2

- BE-PC-OCC JI I*6 TOP

LOCa 7/ 0/ 0 MIINMlENfl 1W.2j

'- ""

600-. I -A. A

IvT Y-, TIV.-'a, I wl - .I

. 11

.400V I' ~'I

1.0

0.8

0.6

0.4

2::

0.2

0.0

-0.2

200 -

0 I i i I . a i i I

I I I •JI I I I I -ICU||| = I I i, I I• .. .. • • •

!0 00 200 300 400 500 600 700 800

REACTOR TIME , SECONDS

18 DENSITY IN THE COLD LEG OF THE INTACT LOOP

LP-SB-2 - TRAC PFI-MODI AND EXPERIMENT COMPARISON
'C' Detector~'

cm

'B'

Source

34.:I cm

Drag disc

turbine meter

C' Detec-.or

urbine blade

'7Drag disc

Drag disc

turbine meter C

S-'' Detector

28.4 cm ID

'D' Detector-.'-"J 'A' Detector

(b) Cold leg (DE.PC-1) INELA 0039

19 Relation of source and detectors to pipe for LOFT gamma

densitometers and flowmeters in intact loop hot and cold

legs.From Reference 4

AEEW - R 2202 ... .................... 51
'111' I'(.L0VIIHi ARE PLOTTED AGAINST REACTOR TI'E

VAPM FRACTION JWinfrithq

KEY

sTH

NAMIE UNITS5

-VAMO FRACTION

L(JC= 2/ 0/ 7 HWMIUVOIO INFxl

TRAC

U.'

0 " 100 200 300 400 500 600 700 800

REACTOR TIME , SECONDS

20 VOID FRACTION AT TOP OF U TUBES

LP-SB-2 - TRAC Pnl-.moO
THE FOLLOWING ARE PLOTTED AGAINST REACTOR TIME. 1Winfr';thl

0l

w~

MIXTURE DENSITY ,DE-PC-0038

KE Y

5Th NAME UNITS

- IIXTIJRt DENSITY* KG/M*.*3

LOC= 3/ 0/ 5 flNEfl=DEN"1 lf=I

- - DE-PC-0038 MIG/ll**3

LOC- Il/ 0/ 0 lINElI.OENI INF.2

rRAC

EXPT

1.0

0.8

0.6

0.4 *

0.2

0.0

-0.2

0 100 200 300 400 500 600 700 800

REACTOR TIME 0 SECONDS

21 LOOP SEAL DENSITY

LP-SB-2 - TRAC PFI-MODI AND EXPERIMENT COMPARISON
TIHE FOLLOWING ARE PLOTTED AGAINST REACTOR TIME

g~J.

0

ts)

lWin Er it

MIXTURE DENSITY ,OE-PC-SO40

KEY

NAME UNITS.

- MIXIURE DENSITY aKG/h**3

LDC= 99/ 0/ 0 IDIlfll=IDENfl IWf=I

1000

--DE-PC-SO'40 IIG/tt**3

LOC- Vif_0/ 0 IINEM-OENf IWf.2

TRAC

9XPT

N,

CI

1.0

0.8

0.6

0.4 *

0.2

O.O

0. 0

-0. 2

U'.

L REACTOR TIME , SECONDS

22 DENSITY IN THE BREAK LINE

LP-SB-2 - TRAC PFI-tlOJIl AND EXPERIMENT COMPARISON
TIE FOLLOVING ARE PLOTTED AGAINST REACTOR TIMt jWI nfr t I

I

'3.

LIOUID VELOCITY ,VAPOR VELOCITY ,FE-PC-O01C

KEY

SM NAMIE LlNITS 801

q LII3JID VELOJCITY M1/SEC

ICC- 7/ C/ 4 tINEtI=VLIU [Wft

--- VAPOR VELOCITY .11/SEC

LOC. 7/ 0/ 4 1MXEI-WAP IW.I

- - FE-PC-OCo CM1/SEC

LOCC I5/ 0/ 0 lltEtlJE 1FF.?

TRAC

EXPT

In

I. 1

0 100 200 300 400 500 600 700 800

REACTOR TIME , SECONDS

23 LIO AND VAP.VELOCITY IN THE COLD LEG

LP-SB-2 - TRAC PF1-MOOI AND EXPERIMENT COMPARISON
0

TIlE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME

LIOUIDVELOCITY aVAPOR VELOCITY ,FE-PC-002A

FE-PC-002C

jWlnfrithý

KEY

SN NAIIE WNITSI am1

-LIOUID VELOCITY *ItSEC

LOC= 99/ 0/ 2 flNEMtaVLIO Ilf'z

-- VAPOR VELOCITY *It/SEC

LOC- 991 0/ 2 IlNEtI-VVAP [Wf-I

TRAC

-FE-PC-002A MI/SEC

LOC. 16/ 0/ 0 IINEti-FE I/ IWf.2 E. - - W: x LAM

.-- FE-PC-002C, /E

LOC= 17/ 0/ 0 flNEIUMF ItF2

U) U),

REACTOR TIME , 5ECONDS

24 LID AND VAP VELOCITY IN THE HOT LEG

LP-SB-2 - TRAC PFI-MODI AND EXPERIMENT COMPARISON
THE FOLLOVING ARE PLOTTED AGAINST REACIOR TIME 1WInfrith1

-j

LIOUID VELOCITY ,VAPOR VELOCITY OFE-IST-001

KEY

SYH NAME UNI TS

BOL

LIOUID VELOC17Y SM/ISEC

LOC= 86/ O/ 8 MNIIE=VLIGI IN=I

-- VAPOR VELOCITY ,M/SEC

LOC- 86/ 0/ 8 MMEM-VAP IWF1

--- FE-IST-O01 ,M/SEC

LOC. 18/ 0/ 0 11NEMI.FE [F=2

TRAC

EXPT

u

w~

REACTOR TIME , SECONDS

25 LID AND VAP VELOCITY IN THE OOWNCOMER OF THE REACTOR VESSEL

LP-SB-2 - TRAC PFI-MOO AND EXPERIMENT COMPARISON
m~J

0

THE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME

FUNCTION ,FE-SLP-O01

WIJnfrlthh

KEY

801 NAME UNITS

- FUNCTION VLIO'• m•nr- i ----------- 4

- -FUNCTION VVAP..

-- FE-SLP-001 H1/SEIC

LOC- 20/ 0/. 0 lINEfi-fE INF.2 EXPT

10

I0

8

(.A

Nir

in 2:

co

-2 0 100 200 300

REACTOR TIME

400 500 600

, 5ECOND5

700 800

26 LIO AND

LP-SB-2

VAP VELOCITY AT CORE INLET

- TRAC PFI-MODI'AND EXPERIMENT COMPARISON
THE FOLLOWING ARE PLOTTED AGAINST REACTOR TIME WInfrithJ

to)

FUNCTION ,FE-SUP-O01

KEY

syM NAHE UNITS

BOL

FUNCTION VLIO

I

-- FUNCTION VVAP V1HAU

EXPT -- FE-SUP-001 . M/SEC

LOCC 22/ 0/ 0 liNEn-FE 1FF-?

10

8

.6

4u

2:

0

-2 0 100 200 300 400 500 600 700 800

REACTOR TIME ,5ECONDS

27 LIO AND

LP-SB-2

VAP VELOCITY AT CORE OUTLET

- TRAC PFI-MOO! AND EXPERIMENT COMPARISON
TIHE FOLLOWING ARE PLOTTED AGAINST REACTOR TIME

hi

hi

0

hi

o~h

0

IWiJnfrl th

LIOUID VELOCITY ,VAPOR VELOCITY ,FE-PC-503

KEY

syM NAME UNITS BOL

- LI1IO VELOCITY *ti/SEC

LOC= 99/ 0/ 0 MNEM=VLIO 11=f *1

--- VAPOR VELOCITY .1M/SEC

LOC- 99/ 0/ 8 IIHEM-WAP IF-.I

- - FE-PC-S03 ,"l/SEC

LOC. 14/ 0/ 0 IINEM.FE IWF.2

r*(KAC

ZXPT

L)

Lo

U~)

N,

0 100 200 300 400 500 600 700 800

REACTOR TIME

28 LID AND VAP VELOCITY IN THE BREAK LINE

LP-SB-2 - TRAC PFI-MODI AND EXPERIMENT

, SECONDS

COMPARISON
• $

THE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME WInfr'ith i

I~J

0

#'3

0~i

I-.

CONTROL OLK 10 -81oFUNCTION

KEY

syM NAME UNITS BOL

- CONTROL OLK I1 -81,

LOC= 0/ 0/ 1 1NE?1=C-8l IFlI

-- FUNCTION

TRAc

EXPT

0 100 200 300 400 500 600 700 800

REACTOR TIME , SECONDS

29 TRANSIENT MASS INVENTORY

4-&PLUS5÷+ PLOTTING UTILITY SYSTEM AEEV
0

.III FOLLOVING ARE PLOTTED AGAINST REACTOR TIME WI nfr ith

SIGNAL VAR. NO. 6, PT-PO04-OIOA

KEY

SBl 801 NAME UNITS

i

- SIGNAL VAR. NO. 6,

LOC= 0/ 0/ 1 HNEflS 6 INF=I

- - PI-PO04.-OIOA M1VA

LOC- 86/ 0/ 0 IHNEK-PRES IlW-2

7000000

TRAC

6500000

EXPT

6000000

5500000

5000000

4500000

K

"S

5'

5'

5'

5'.5.

5'

5''S.

5'.

5'

5'

5'

5'

5'

5'

'5

5'5'

5'

'5

N 5'

5'

5'N -'S

7.0

6.5

6.0

5.5 t2

E.

5.0

4.5

I

S.

LluJuJujJu, 4.0

0 500 1000 1500 2000 2500 3t 00

REACTOR TIME , SECONDS

30 SECONDARY SIDE PRESSURE

LP-SB-2 - TRAC PFI-MODI AND EXPERIMENT COMPARISON
'IIII. FOI.LLIIlNG ARE PLOTTED AGAINST REACTOR TIME

SIGNAL VAR. NO. 2,SIGNAL VAR. NO. 6

lwin fr it Ii

tlj

til

0

0~

CA)

KEY

5sy NAME ULNITS BOL

- SIGNAL VAR. NO. 2,

LOC= .0/ 0/ I HHEH=S 2 INF=I

--- SIGNAL VAR. NO. 6,

LOC- 0/ 0/ 1 HNEtM.S 6 INF-I

0. 20E

0. I8E

TRAC

0. 16E

0. 14E

•0. 12E

0. IOE

0. 80E

0. 60E

0. 40E

0. 20E

0. OOE

Sl00 1000 1500 2000

PFAr:'Tni TIIE , 5ECONIS

SI Al I."Y I 'I"ESURES IN TRAC

.11 1.11f)11 AND EXPERIMENT COMPARISON

31. PRIM1ARY AND '11
0

t'j

TIHE FOLLOWING.ARE PLOTTED AGAINST REACTOR TIME

SIGNAL VAR. NO. 2,PE-PC-002

1Winfrithl

KEY

SYM NAME UNITS

BOL

i-- SIGNAL VAR. NO. 2,

LOC= O/ "0/ 1 HINEIIS 2 I[WI

- - PE-PC-002 , IvA

LOC- 771 D/ 0 tlNEfl.PRES JIU-2

0. 20E

0. 1BE

TRAC

0. 16E

EXPT

0. 14E

0. 12E

0. iOE

0. 80E

0. 60E

0. 40E

0. 20E

0. OOE

20

18

16

14

12

10

8

6

4

2

0

0.

0 500 1000 1500 2000

REACTOR TIME , SECONDS

32 INTACT LOOP HOT LEG PRESSURE

LP-SB-2 - TRAC PF-l-MOOl AND EXPERIMENT COMPARISON
THE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME

LIOUID TEMPERATURE ,TE-PC-0028

WUlnfr ithI

t~j

0

KEY

SN NAME UN4ITS

- LWtJID TEMP'ERATUR~E DOEG.K

LOC- 99/ o/ 2 IINEtWTEL Ilfsl

TRAC

- - 7E-pc-0028 DOEG.KZ

LOC- 130/ 0/ 0 MNEII-TtICL INW.2 EXPT

--IJ

0

0 500 1000 1500 2000 2500

REACTOR.TIME , SECONDS

3000

33 LIO TEMPERATURE IN THE HOT LEG OF THE INTACT LOOP.

LP-SB-2 - TRAC PFI-Mt01 AND EXPERIMENT. COMPARISON
I.

t00

TIII FOLLOIH1G ARE PLOTTEO AGAINST REACTOR TIME

FUNCION

KEY

180 --- w W w • w I I l

S" NAME UNITS

8(m.

4I- FUNCTION.

1601

-2-. FCTlON

-3-. FUNCTION

TRAC

140 I

120[-

1Winfrithh

at HPIS location

1.75 m after HPIS

I001l

80[

4

I

601

40

20

1.52 m before HPIS

0 200 400 600 80010001200140016001800200022002400260020003000

REACTOR TIMlE •, SECONDS

34 COLD LEG

,-+PI.US++

TEM SAT - TEM LIO

PLOII ING UTILITY SYSTEM AEEW
TIHE FOLLOWING ARE PLOTTED AGAINST REACTOR TI1E

CLADDING TEMP7 -FINE,TE-5HO7-050

Winfritht~J

C

t,3

KEY

SYi. NAME UNITS

BOL

C- LADOING TEMP -FINE,OEG.K

LOC. 88/ I 6 MNEM=I'MCL IWF=I

-- TE-51107-058 , DEG. K

LIE- 272/ 0/ 0 IiNEM-7MCL DINF2

TRAC

lEXPT

uJ

0

500 1000 •1500 2000 2500 3000

REACTOR TIME SECONDS

35 CLADDING TEMPERATURE NEAR TOP OF THE CORE

LP-SB-2 - TRAC PFI-MOOI AND EXPERIMENT COMPARISON
THIE 'FOLLOVING ARE PLOTTED AGAINST REACTOR TIME WInfrith

"3

0*

"3

MIXTURE DENSITY

DE-PC-002C

,DE-PC-002A ,DE-PC-0028

KEY

Bt0 NAME UNITS

- MIXTURE DENSITY ,KG/H**,3

LOC- 99/ 0/ 2 MNEtl.DEN4 INsI

TRAC

I-..--

- - DE-pc-002A , IL'11**3 1 i!KPL

LOC- -8/ 0/ 0 lINEM-OENfl INF=2 BOTTOM

--- E-PC-002B MfG/M-P*3 MIDL

LOC. 91 0/ 0 IINEfl.ENMIINrFzrIDL

- DE-PC-002C , HG/11* s3 ITOP

LOC= 10/ 0/ 0 flNEMlDENi1 UF=2

1.0

0.8

0..6

0.4

2:: N,

0.2

0.0

0%

1-0.2

3000

REACTOR TIME , SECONDS

36' DENSITY IN THE HOT LEG INTACT LOOP

LP-SB-2 - TRAC PFI-MODI AND EXPERIMENT COMPARISON
THE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME

ti'

t'j

0

~0

MIXTURE DENSITY

DE-PC-O0IC

,DE-PC-OO1A ,DE-PC-OOIB

lWInfrlth'

I

KEY

STh NAME UNITS

- MIXTURE DENSITY KGAio.3

LOC= 7/ O/ 4 flNEM=O=ENt IRFzI

TRAC

4.

-- BE-PC-OO IA 'mm*M/1i3

LOC- 5/ 0/ 0 IINEM.OENM INF-2

---DE-PC-0018 MG/Mp341

LOC- 6/ 0/ 0 t1NEM-OENMINFlf2

- DE-PC-OCIC MIG/I1oss

LOC. 7/ Of 0 tiNEM=D4ENfl If.?

BOTTOM

MIDDLE

TOP

to

V tE)V

V

2Z

N

C,

r

REACTOR TIME , SECONDS

37 DENSITY

LP-SB-2

IN THE

- TRAC

COLD LEG OF THE INTACT LOOP.

PFI-MOO AND EXPERIMENT COMPARISON
:0

'Ui

-.4

lIIE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME

MIXTURE DENSITY ,DE-PC-SO48 fI

WInfr Ithl

KEY

I

syi NAME UN4ITS 80L

-MIXTURE DENSITY KiG/tt**3

LOC.= 99/ 0/ 0 IINEH=)ENN INF:I

TRAC

ýXPT - - DE-PC-SO483 tlG/ti**3

LOC- V/ 0/ 0 MNEM.0ENM1 IWf.2

1.0

0. 8

0.6

0.•4

(:3

0.2

0.0

-3

1-0.2

0 .500 1000 1500 2000 2500 3000

REACTOR TIME . SECONDS

38 DENSITY IN TIlE

LP-SB-2 -'TRAC

BREAK LINE

PFI-MODI AND EXPERIMENT COMPARISON
:to

tu, THE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME WInfritthl

gLOUI VELOCITY ,VAPOR VELOCITY ,FE-IST-O01

KEY

5Th NAME UN ITS

- LIOUID VELOCIIT ,M/5EC

LOC= B6/ Of 8 MINEMi=VLIO IlHFl

TRAC

--- VAPOR VELOCITY "/SEC

LOC- 86/ O/ 8 IttEH-WAP IF-I

-- FE-IST-O01

LOC- 18/ o/ 0 lINE•-FE 1W.2-? EXPT

UILJ (nl

0 500 1000 1500 2000 2500 3000

REACTOR TIME , SECONDS

39 LID AND

LP-SB-2

VAP VELOCITY IN THE OOWNCOMER OF THE REACTOR VESSEL

- TRAC PFI-MOOl AND EXPERIMENT COMPARISON
THE FOLLOVING ARE PLOTTED AGAINST REACIOR TIME

I

t')

0

FUNCTION ,FE-SLP-001

JUJ In fr th

10 KEY

SY" NAME UNITS

BOL

- FUNCTION VLIO t [~n - n I IflAL

--- FUNCTION VVAP

- - FE-SLP-001 *tt/SEC

LOC. 20/ 0/ 0 IINEtI.E INF.? EXPT

a

6

4 u

2

0

-J

I-2

0 500 1000 1500 2000 2500 3000

REACTOR TIME , SECONDS

40 LIO AND

LP-SB-2

VAP VELOCITY AT

- TOAC PFI-MODI

CORE INLET

AND EXPERIMENT COMPARISON
0

TllE FOLLOVING ARE PLOTTED AGAINST REACTOR TItlE

PUJMP DEI.TA-P ,PDE-PC-001

lWinfr'ithil

KEY juutuu

syi NAME U4IS 450000)

- PUMP DELTA-P NIH/,**2 TRAC

LO[= 4/ 0/ 1 INE'=0ELP WH=I 400000

--- POE-PC-O01 ,KPA 1EXP,'

LOC. 65/ 0/ 0 HINEti.PO INF'2 350000

300000

250000

e 20W00)

z 150000

100000

50000

n

ItS -- i

- 500

450

400

350

300

250

200

150

100

50

0

-50

--100

5000

n~

-50000

-I06000

0 500 1000 1500 2000

REACTOR TIME , SECONDS

41 PRESSURE DIFFERENCE OVER THE MAIN COOLANT PUMPS

LP-SB-2 - 1rPlM: PFI--MOlI AND EXPERIMENT COMPARISON

2500
E THIE FOLLOWING ARE PLOTTED AGAINST REACTOR TIME 1WInfr'ith

I~J

0

sI~J

-a

FUNCTION ,FE-5UP-0O01

KEY

SYtl NAME UNITS

BOL

- FUNCTION VL.IO _

-- FUNCTION VVAP

-- FE-SUP-O01 I1/SEC

LOC- 22/ 0/ 0 KNEM-FE INF-2

rRAC

ýXPT

10

8

6

40

in

2:

0

FI -2 0 500 1000 1500 2000 2500 3000

REACTOR TIME

42 LID AND

LP-SB-2

VAP VELOCITY AT CORE OUTLET

- TRAC PFI-MOOD AND EXPERIMENT

, SECONDS

COMPARISON
0

It,)

THE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME

LIOUIO VELOCITY

FE-PC-O02C

,VAPOR VELOCITY ,FE-PC-002A

KEY

5TYi NAME UNITS

BOL

1111110O VELOCITY , H/SEC 1rv nnfI n, I~ j muCIf %n i u

""= .. . ........ 2' 'ITRAC --- LOC- VAPOR 99/ VELOCITY 0/ 2 NNEI-VVAP ti/SECNF-I

- - FE-PC-002A ,IM/SEC

LOC. 16/ 0/ 0 fiNEt.FE 1NF=2

FE-PC-002C MH/SEC

LOC= 1?/ 0/ 0 IIHEt=FE INF=21

-4

Lu

U)

w:

0 500 1000 1500 2000 2500 3000

REACTOR TIME , SECONDS

43 LIO AND VAP VELOCITY I.N THE HOT LEG

LP-SB-2 - TRAC PFI-MODI AND EXPERIMENT COMPARISON
THE FOLLOWING ARE PLOTTED AGAINST REACTOR TIME

LIOUID VELOCITY 1VAPOR VELOCITY ,FE-PC-OOIC

Winfri th]

M3 KEY

i• NAME UNITS

aOL

- LIOVID VELOCITY tI/S.C

LOC= .7/ 0/ 4 MNEM=VLIO I1•=1

I

J • I UL•f V

-r"nrv

--- VAPOR VELOCITY ,tl/5EC

LOIC 71 0/ 4 IINEH-VVAP (W-I

A &I%

EXPT

I

I - -FE-PC-OOIC ,ti/SEC

LOC- 15/ 0/ 0 tlNfllFE IHF-2

ULu

cn1:)

--J

0 500 1000

REACTOR TIME

1500 2000

SECONDS

2500 3000

44 LID AND VAP VELOCITY IN THE COLD LEG

LP-SB-2 - TRAC PFI-MODI AND EXPERIMENT COMPARISON
IIIDIH I IVEJOIT

LllIQUI VELOC!ITY

ARE PLOTTED AGAINST REACTOR TIME

,VAPOR VELOCITY ,FE-PC-S03

Iii

N)

N)

0

N)

KEY

SYM NAME UNITS

BOL

-- LIUID VELOCITY ai/SEC

LOC= 99/ 0/ 8 MNEM=VLIU IF=I

I

I IDI R II• P"n ^ A flfl1ý

--- VAPOR VELOCITY ,MfISEC

LOC. 99/ O/ 8 tHEfWVVAP LtW.1

FE-PC-S03 *Il/sEC 1

ILOC- I4/ 0/ 0 IINEti.FE IWf.2 JEXPT

u

ILJ

.'}

-,..

0 500 1000 1500 2000 2500 3000

REACTOR TIME , SECONDS

45 LID AND

IP--SB-2

VAP VELOCITY IN

- TRAC PFI-lioni

THE BREAK LINE

AND EXPERIMENT COMPARISON
o

I

I

i

$

t

*TiIL FOI.LOVINr ARE PLLOTTED AGAIN5T REACTOR TIME

M1ASS Fl.flJI RATE FT-PI39-27-I ,FT-P139-27-2

UJI nfri th

!

0

tj

KEY

SYM NAMIE UNITS5 BoL

- MASS FLOY PAlE KtG/SEC

LOC= 1/ 0/ 3 t1NEM=FLOV hMflF

- - FT-P139-27-1 KGISEC

LOC- 30/ O/ 0 fiNEM1FLOV INF-2

TRAC

EXPT --.FT-PI39-27-2 KG/6SEc

LOC- 31/ 0/ 0 MNEfl=FLOI 1WI.2

tCl

L3 U1)

0,

2000

REACTOR TIME SECONDS

46 HOT LEG

LP-SB-2

MA•S FLI.IOW •AII- AT VENTIJRI LOCATION

- "RAC PFI-MODI. AND EXPERIMENT COMPARISON
THE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME IWInfrithlh

:0

MASS FLOV RATE ',FR-PC-S03

1

KEY

fuM NAME U.N ITS

U•,'. I'l

- BASS FLOV RAIE *KG/SEC

LOCs. 98/ 0/ 1 IINEI.FLOV IFFuI

- - FR-PC-S03 * KG/SEC

LOC. 23/ 0/ 0 tINEtI4FLOV HF-2

TRA'C

EXPT

1

10

u

in

',,. L2

0 500 1000 1500 2000 2500 3000

REACTOR TIME , SECONDS

47 BREAK MASS FLOW.RATE

LP-SB-2 - TRAC PFI-MODI AND EXPERIMENT COMPARISON
0

'S

THE FOLLOWING ARE PLOTTED AGAINST REACTOR TIME

RtOL BLK ID -81,FUNCTION

1WInfrith

CONT

KEY

SYM BOL NAME UNITS

- CONTROL BLK 10 -81,

LOC= 0/ 0/ 1 I1NEIM=C-81 INFzt TRAC

-- FUNCTION k6XPT

0 500 1000 1500 2000 2500 3000

REACTOR TIME , SECONDS

48 TRANSIENT

++PLUS++

MASS INVENTORY

PLOTTING UTILITY SYSTEM AEEV I
THE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME lWinfri thý MIXTURE DENSITY ,OE-PC-SO4B

1-4

KEY

syli BOL NAME UNITS

- I1IXML~ OENSITY IKG/fl..3 PRAc

LOC- 95/ 0/ 4 IINEtI=DENII I[f.I

- - DE-PC-S0O8 gtlG/11*3 IXP

LOC- 4/ 0/ 0 flREl-DERtI IWIf2 XP

1.0

0.8

0.6

0.4 *

0.2

0.0

-0.02 3000 0 500 1000 1500 2000 2500

REACTOR TIME ., SECONDS

49 DENSITY

LP-SB-2

IN THE BREAK LINE

- TRAC.PFI-MODI AND EXPERIMENT COMPARISON
N

N

C

N

THE FOLLOWING AR

MASS FLOW RATE

E PLOTTED AGAINST REACTOR TIhE Winfrith

,FR-PC-S03

KEY

I

syi NAME UN ITS 001

-HtASS FLOV RAIE *KG/SEC

LOC= 98/ 0/ 1 tlNEti=FLOV IWnI

I TRAC

- - FR-PC-S03 , KG/SEC EXL:

LOC- 23/ 0/ 0 ttl-FLOV INF-2

I

U

cn

03

0 500 1000 1500 2000 2500 3000

REACTOR TIME , SECONDS

s0 BREAK MASS FLOW RATE

LP-SB-2 -TRAC PFI-MOOI AND EXPERIMENT COMPARISON
THE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME

CONTROL BLK I1 -81,FUNCTION

lWinfr Ith

I ,I

co)

KEY

5Th NAME UN1TS

BOt

-CONTROL OLIK 1D -81,

LOC= 0/ 0/ 1 tiNEI1C-OI INF=I

[- - FUNCTION

TRAC

EXPT

6000

5500

5000

4500

4000

3500

3000

2500

2000

1500

1000

500

NN

N N N

N N

I I I I I

ft

I i -

0 500 1000

REACTOR TIME

1500 2000

, SECONDS

2500 3000

51 TRANSIENT MASS

++PLUS++

INVENTORY

PLOTTING UTILITY SYSTEM AEEW
0.

THt FOLLOVING ARE PLOTTED AGAINST REACTOR TIME

SIGNAL VAR. NO. 2,PE-PC-002

Winfrith

KEY

5Th NAIIE LIN1

801

- SIGNAL VAR. NO3. 2,

LOC= 0/ 0/ 1 HKNEHS 2I

-- PE-PC-002 HPA

LOC- 771 0/ 0 1INEM-PRES I1

0.20E

TS 0. 18E

w TRAC

0.16E

W-2

0. 14E

0. 12E

0. 1OE

0. 80E

0. 60E

0. 40E

0. 20E

0. DOE

20

18

16

14

12

10

8

6

2

0

4:

0. r

0 500 1000 1500

REACTOR TIME

52 INTACT LOOP HOT LEG PRESSURE

LP-SB-2 -" TRAC PFI-MOOl AND EXPERIMENT

2000

SECONDS

COMPARISON
1HE FOLLOWING ARE PLOTTED AGAINST REACTOR TIME lWI nfrith

SIGNAL VAR. NO.

I~3

g~3

0

0,

Lfl

6, PE-SGS-001

KEY

NAME UNITS

- SIGNAL VAR. NO. 6,

LOC. 0/ 0/ 1 KlNEti=S 6IWFuI

-- PE-SGS-001 tvI

LOC= 81/ 0/ 0 IlElH-PRES 1NF-2

7.0

6.5

6.0

5.5

0.

5.0

4.5

4.0

0 500 1000 1500 2000 2500 3000

REACTOR TIME SECONDS

COMPARISON

53 SECONDARY SIDE

LP-SB-2 - TRAC

PRESSURE

PF1-MOD1 AND EXPERIMENT
N) N)

0~

N)

THE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME

LIOUID TEMPERATURE ,TE-PC-0028

JWI n fr7lth

KEY

Sy" NAMIE UNITS

- iWoIn TWIERATLIRE *DEG.t:

LOC. 99/ 0/ 2 tflN-EflTI IWf.I

- - 7E-PC-0020 cEo. K

LOC- 130/ 0/ 0 IINEH.ThCL Iif-2

TRAC

EXPT

U

REACTOR TIME , SECONOS

54 LIO TEMPERATURE IN THE HOT LEG OF THE INTACT LOOP

LP-SB-2 - TRAC PFI-MODI AND EXPERIMENT COMPARISON
THE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME

CLADDING TEMP -FINE, TE-5H07-058

Winfrith

0

co

K~EY

5yti NAM1E UNITS BOL

-CLAWJING TEM1P -FINE*OEG.K

LJCs SO/ 1/ 5 IINEI=TCL Ilfal

- - TE-SHO?-058 *DEG. K

LOC- 272/ 0/ 0 WEIMHf.hL 1WF.2

rRAC

EXPT

REACTOR TIME , SECONDS

55 CLADDING TEMPERATURE NEAR TOP OF THE CORE

LP-SB-2 - TRAC PFI-MODI AND EXPERIMENT COMPARISON
1HE FOLLOWING ARE PLOTTED AGAINST REACTOR TIME lWinfrith

tJ

0

g~J

MIXTURE DENSITY

DE-PC-002C

,DE-PC-002A ,DE-PC-OO2B

KEY

Sylh NAME UNIJS

-MIXTURE DENSITY *KG/H**3

LDC= 99/ 0/ 2 MNOfLsJERNf lIN~u

- - DE-PC-002A *11G/fl.3

LOC- B/ 0/ 0 IINEM-DENM INF-2

DE-PC-0028 8 MG/M1..3

LOC- 91 0/ 0 MHEtI-DENtII UF.2

- DE-PC-002C GM3

LOCu 10/ 0/ 0 IINEM=DENM IIV.=2

TRAC

KXPT

BOTTOM

4IDDLE

"Op

(3

1.0

0.8

0.6

t- 0.4

A- N,

0.2

0.0

-0.2

CDol

REACTOR TIME , SECONDS

56 DENSITY IN THEI 'HOT LEG INTACT LOOP

LP-SB-2 - TRAC PFI-MODI AND EXPERIMENT COMPARISON
THt FOLLOWING ARE PLOTTED AGAINST REACTOR TIME WiInfr I th

tD

MIXTURE DENSITY

DE-PC-O01C

,OE-PC-001A ,DE-PC-OO1B

KEY

SYll NAME UNITS

- MIXTURE DENSITY ,KG/M**3

LOC= 7/ 0/ 4 MNEM=OENI INFOI

I

TRAC

- - DE-PC-00IA tiIG/M**.3

LOC- 5/ 0/ 0 tHNEfl-ENHI IF-2

---DE-PC-0I01 MlG/fl*#3

LOC. 6/ 0/ .0 tiNEH.DENMII W-2

-DE-PC-0OIC tiIG/M*#3

LOC- 7/ 0/ 0 IINEM-ENtI INF=2

Er AFT

BOTTOM

MIDDLE

TOP

rN, (39 lz

1.0

0.8

0.6

0.4

0.2

Q. 0

1-0.2

0 500 1000 1500 2000 2500 3000

REACTOR TIME , SECONDS.

57 DENSITY IN THE

LP-SB-2 - TRAC

.COLD LEG OF THE INTACT LOOP

PFI-MODI AND EXPERIMENT COMPARISON
rT-E FOLLOVING ARE PLOTTED AGAINST REACTOR TIME WI nf, I:,th

1%)

0

LIQUID VELOCITY ,VAPOR VELOCITY ,FE-IST-O01

KEY

syl NAME UNITS

-LIOJID VELOCITY Mf/SEC

10Cm 86/ Of 8 flNffVLIO IWat

10

a m•L -- - n.-

- - VAPOR VELOCITY tV1SEC

LOC- 86/ Of a im~ti-VVAP Iw-I

- -FE-IST-00t I tt/SEC

LOCms I8/ Of 0 MMFIIE IPV.2

EXPT

6

LuU)

cn

4

%0

0i

2

0

Vi•.•

-2

0 500 1000 1500 2000 2500 3000

REACTOR TIME S SECONDS

58 LID AND VAP VELOCITY IN THE DOONCOMER OF THE REACTOR VESSEL

LP-SB-2 - TRAC PFI-MOOI AND EXPERIMENT COMPARISON
THE FOLLOVING ARE PLOTTED AGAINST REACTOR TIIE

VAPOR FRACTION

Wunfr'I th

hi

hi

0

hi

~0

KEY

SY" NAME UNITS

V- APOR FRACTION

LOC= B8/ 0/ 5 WHNEIVOIO ItFI TRAC

0 500 1000 15001 ")5"..00 3000

.REACTOR TIME

59 VOID FRACTION TOP FUEL RZEGION

LP-SB-2 - IRAC PFI .J101J11

:-;1 I.I IIIIl"•
TiHt FOLLOWING ARE PLOTTED AGAINST REACTOR TIME 1WInfrith

0

'0

FUNCT[ON ,FE-SLP-00I

KEY

SYlI NAME tNITS

BOL

- FUNCTION VLTO a

--- FUNCTION VVAP -------- I

--- FE-5LP-O01 M/SEC

LOC- 20/ 0/ 0 MNEM-FE INF-2

TRAC

EXPT

6

4u

Iii

2

.0

-2

0 500 1000 1500 2000 2500 3000

REACTOR TIME , SECONDS

60 LID AND

LP-SB-2

YAP VELOCITY AT CORE INLET

- TRACPFI-MODI AND EXPERIMENT COMPARISON
TA-• FOLLOVING ARE PLOTTED AGAINST REACTOR TIME iU~nfrith

t.J

t~j

0

g~J

w

LIOUID VELOCITY

FE-PC-002C

,VAPOR VELOCITY ,FE-PC-002A

KEY

syf BOL NAME UNITS

- LIOUIO VELOCITY "M/SEC

LOC- 99/ 0/ 2 liNEI'IVLIO IlFuI

I

I

-- VAPOR VELOCITY #"l/SEC

LOC- 99/ O/ 2 HNE,,Wl.AP IE-I

TRAC

- - FE.-PC-002A ,ti/SEC

OCC. 16/ 0/ 0 fiNEII-FE INF.2

I

..z•,v z,,z m

---FE.4'C-002C . ,fl/5EC

LOCC 17/ 0/ 0 tINEII=FE IW.2

EArT

tLi

-21

0 500 1000 1500 2000 2500 3000

REACTOR TIME , SECONDS

61 LIO AND VAP VELOCITY IN

LP-SB-2 - TRAC'PFI-MODI

THE HOT LEG

AND EXPERIMENT COMPARISON
I~J

t~)

0

~0

THE FOLLOVING ARE PLOTTED AGAINST

PUMiP DELTA-P ,POE-PC-00i

REACTOR TIME- lwlnfr'i th

K~EY

Sml NAME UNITS 801

- P"ti OELTA..P *NAIII.2

LOCse 4/ 0/ 1 IIMWJEWLP IN~at

-POE4)C-00 I *KPA

ICC- 65/ 0/ 0 tINJ-PO [Wf.2

500000

450000

TRA'C4 0J0O

EXPT

350000

300000

250000

200000

z 150000

100000

50000

10

-50000

-100000

"I

I I I 500

450

400

350

300

250

200

150

100

E•o

n_

0.

.- -~ -- a. - -

I a a I

0 500

I 

1000

I 3

)00

] -50~

REACTOR TItlE

1500 2000

SECONDS

2500 3C

62 PRESSURE DIFFERENCE OVER THE MAIN COOLANT PUMPS

LP-SB-2 - TRAC PFI-MOOI AND EXPERIMENT COMPARISON
THIE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME WI nfr' ihR

t~J

0

'a

Lfl

MASS FLOV RATE ,FT-P 139-27-1 FT-P139-27-2

KEY

SYt NAME UNITS

BOL

- MASS FLOV RATE K~G/5ECL

LOC= I/ Of 3 tlNEtlFLOV I t rRAc

- - FT-PI39-27-1 .KG/SEC

LOC. 30/ 0/ 0 ItWEI1fLOV hr-? IXP - FT-PI39-27-2 KG6/SEC

LOC. 31/ 0f 0 ?iNE"MJLDV [W-2

0 500 1000 1500 2000 2500 3000

VRFACTOR TIME , SECONDS

63 HOT LEG

LP-SB-2

MASS FLOW RAT1- AT VENTURI LOCATION

- TRAC PFI-MOf)I AND EXPERIMENT COMPARISON
Tit FOLLOVING ARE PLOTTED AGAINST REACTOR TIME tWinfrithl

M

0

LIOUID VELOCITY ,VAPOR VELOCITY ,FE-PC-S03

I

KEY

SYti NMlE UNIITS

801.

-LIQUID VELOC ITY Hf/SEC

LOC- 95/ 0/ 4 JINEHaVL10 IWf=I 9"Ru

- - VAPO VELOCITY Mf/SEC

LOC- 9S1 0/ 4 tNEH-WAP INF.I

- - FE-PC-S03 tV1SEC

LOC- I'4/ 0/ 0 IlNfl-?E ItE.2 RXPT

U)

0 500 1000 1500 2000 2500 3000

REACTOR TIME , SECONDS

64 LIG AND VAP VECOCITY IN THE BREAK LINE

LP-SB-2 - TRAC'PFl-MOD1 AND-EXPERIMENT COMPARISON
EXPER I MENT LP-SB-2

.11

on

30 Z

10

0 Tooo 2000 3000 Time (s•)

Al Measured and adjusted cold leg densities at the steam

qenerator 6utlet. From Reference 4

AEFW- R 2202 97
80

80

40

20

a 0 0 0 L3-8

41% x LP-88-2I

6~

x

0

0.0 0.2. 0.4 0.8 0.8 1.0

Void fracion

A2 Pump head as a function of void fraction for Experiments

LP-SB-2 and L3-6. From Reference 4

AEEW - R 2202 .-98
13L3-O

80 I..

- U. ..3 :

2D~

0.0 0.2 0.4 0.8 0.8 to

Void fraction

A3 Pump head as a function of void fraction obtained using the

adjusted density at the steam generator outlet for Experimnent

LP-SB-2. From Reference 4

AEEW - . 2202 .99
THE FOLLOWING ARE PLOTTED AGAINST PUMP VOID FRACTION

FUNCTION

IWinfrrithl

N

1')

I~.)

0

0

0*

KEY

SYn NAME UNIITS

OPL

, FUNCTION PUMP 2,

a I I

100

TRAC

80

A AA

hAA

A

A

Af

A]

A FUNCTION PUMP 1 ,

60

40

6 A

A~~

A

~ AA~ 0

AA

t

20

A' II | Iz It In

I ! II !

-20 -

0.0 0.2 0.4 0.6 0. 1.0

PUMP VOID FRACTION

A4 PUMP HEAD VS VOID FRACTION IN RUN A

+ PLOTTING UTILITY SYSTEM

8

++PLUS+• AEEW
THE FOLLOWING ARE PLOTTED AGAINST REACTOR TIME WInfrithl

MIXTURE DENSITY ,DE-PC-0038

:to

KEY

SYM BOL NAME UNITS

4- MIXTURE DENSITY ,KG/M,**3

LOC- 3/ 0/ 7 INE=-OENHM IWF--

1.0

TRAC

--2-- DE-PC-003B *IE/t1..3 6XPT

LOC- Il1/ 0/ 0 MNE?1.DENf INF-2

0.8

0.6

Fo,

:1

ro 0.4

0.2

0.0

-0. 2

REACTOR TIME , SECONDS

A5 LOOP SEAL DENSITY IN RUN A

++PLUS++ PLOTTING UTILITY SYSTEM AEEW

++PLUS+-i -PLOTTING UTILITY SYSTEM AEE~I

I
I .

:to! . 'Si

0

"H.

THE FOLLOWING ARE PLOTTED AGAINST VOLUMETRIC FLOW RATE

PUMP DELTA-P

Winfr-IthKEY

SYM NAME UNITS

BOL

0 PUMIP DELTA-P ,N/1**.2

LOC= 4/ 0/ 1 ItNEI---ELP IfW=l

A PUMP DELTA-P ,N/t1*.*2 Ti

LOC- 5/ 0/ 1 INtI..OELP IFW-I

500000

450000

A C 0 0 0 0 0

350000

300000

250000

N °

E- 200000

z

150000

100000

50000

0-

-50000

-0. I0

A6 p

++PLUS++

D I

&

£

A.

£

A# 500 sec

ý6

A AAtAI 

90 0 se

" "" ."PUMP ".

PUMP

A

1

C

I A

4

-i p ;-t p p

I S

-0.05 0;00 0.05 0.10 0.15 0.20 0.25 0.30.

, VOLUMETRIC FLOW RATE , M**3/5EC

UMPS PRESSURE INCREASE VS VOLUMETRIC FLOW

PLOTTING UTILITY SYSTEM

0.35 0.40

RATE IN RUN A

AEEW
to

0

e

t THE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME

MASS FLOW RATE

Wllnfr'ith

I)t/.

KEY I

5YI NAME UNITS BOL

--- MASS FLOV RATE *KG/SEC

LOC= 4/ 0/ 1 tKM--FLOV NFaI

--- MASS FLOV RATE *KG/SEC

LOC- 5/ 0/ 1 HNEI-FLOV IW-I

e

I 200 .

180

1601-

i

140-

u

i 120

N )

" 1001 0

w.

80

60

* K I\j*

I UMPUMP I, 2

' ,

. .. .. t! . ! pump 1 ',ii l

I 'I

40

20

II

I

I 1% 1)1----44,j ,, I 5~ I* - I I I ". Vy 1 -- I I I I I-

-20 1 1 1 1 , , 1 , - 1 1 1 1 1

0 200 400 600 80010001200140016001800200022002400260028003000

REACTOR TIME , SECONDS

A7 PUMPS MASS FLOW RATE IN RUN A

++PLUS++ PLOTTING UTILITY. SYSTEIM AEEW

+--PLUS++ PLOTTING UTILITY. SYSTEM AEE1~
EXPER I MENT LP-SB-2

33o

B" 250

200

150

100

500 1000 1500

Time (s)

A8 Primary coolant pump power.

From Reference 4

2000

AEEW - R 2202 104
THE FOLLOVING ARE PLOTTED AGAINST REACTOR TIME

PLUiP TORQUE

Iwinfrlth

i

I~3

I~3

0

I-.

Oi In

KEY

SYII NAMIE UNITS BOL

--- PU"P TOROUIE KG* V**;

LOC= V1 0/ 1 MNEH=TORO IWF=I "|" 14F Aft "

, npkký

- - PUMIP TOROUE *KG* V..;

LOC. 5/ 0/ 1 WIEII-JORO IFW-I

c'J

1000 1500 2000

REACTOR TIME , SECONDS

A9 PUMPS TORQUES IN RUN B

++PLUS++ PLOTTING UTILITY SYSTEM AEEW
I THE FOLLOW1NG ARE'PLOTTED AGAIN5T REACTOR TIME

MASS FLOV RATE

iWin fri thl

0,.

0,.

KEY

MAS- LO RATE K~G/SEC1

LOC= 4/ 0/ MNEfl=FLOV W rrl IQP A Ir•

- - MASS FLOV RATE ,KG/SEC

LOC- 5/ 0/ 1 MNEM-FLOV IW-I

260

240

220

200

180

160

140

120

100

80

60

40

20

1%

I

~E.

'I

I

uLJwD

(n

'I,

', PUMP 2

*l PUMP I

I \

-- -I 

-201

rrW -7 - \x• 'i-I " *t

, I I m i I I

0 500 1000 1500

REACTOR TIME

AlO PUMPS MASS FLOWS IN

PLOTTING UTILITY SYSTEM

2000

, SECONDS

RUN B

2500 3000

++PLUS++ kEEW&

++PLUS+-i -AEEII
:to

t%)

0

THE FOLLOVING ARE PLOTTED AGAINST TIMlE

DE-PC-OO2A ,DE-PC-002B rir ic..f(lfpc DE-PC-S04B

WInfrithi

KEY

8OL NAME UNITS

1-.--

- - DE-PC-0O2A ,'MG/M.,3 rýA-"i

LC'=. 8/ 0/ 0 HNEM=IDEM INF=2 BOTTOM 0. 8

---- DE-FPC - 002B MG/M o*3 -I D D L E

LOC= 9/ 0/ 0 MINEM-JENM If.F2 I --- DE-PC-002C ,fIG/M.3 .yOp

LOC- W/ 0/ 0 0.EM6DENM INF2 1

DE-PC-SO4B ... .. t ' I Ij " '. * . .4 $ F . .. , 6

LOC= 4/ O/ 0 HNEm=DE0N"I INF=2

t".

* 0.4

0.2

0.0

-0.2

-5

Bi

++PLUS++

0 0 500 1000 1500 2000 2500 3000

TIMlE , SECONDS

EXPERIMENTAL HOT LEG DENSITY AND BREAK LINE

PLOTTING UTILITY SYSTEM

4000

!

!

DENSITY

AEEV
ji

Hil*

3 2 -i

ORIGINAL CONFIGURATION RUN A

cvi

Special iEin 92z

only junction A

( FR IC I.E 2 0) 

.I

Quality Control

Valve

Quality Monitored

here

Special Winfrith

stratified offtake

mode-l-at this junction

QUALITY CONTROLLING

CONFIGURATION RUN B

B2 NODING MODIFICATIONS IN THE BREAK LINE

AEEW - R 2202 io8
,ruAL.

x PrT

vdtJ Pottiou STEM

B3 OUALITY CONTROL VALVE CONTROL LOGIC

AEEW - R 2202 109
THE FOLLOVING ARE PLOTTED AGAINST VAPOR FRACTION

FUNCTION !

...

i

tp,

t~)

0

KEY

SYl

0Ol NAME UNITS

" FUNCTION

" FUNCTION

A FUNCTION

TRAC

1WInfrith

Transitional Regior

to fully stratifiec

flow

0.9

OVAPOR FRACTION

cl TRAC FLOW REGIME MAP FOR LOFT LP-SB-2 HOT LEG CONDITIONS RUN 1
'.3

1%)

0

NJ

I-.

I-.

"IIIE FOIIJING ARE PLOTTED AGAINST VAPOR FRACTION

REACTOR TIME

lWinfrith

KEY

SYt BOL NAME UNITS

-4- REACTOR TIME ,SECONOS

LUCx 99/ 0/ 2 HlNEtH=TIlKE INFzt TRAC

cn

03

z

03

C-)

'II

(I)

0.9

VAPOR FRACTION

C2 TIME VS HOT LEG VOID FRACTION IN RUN B
TABLES

AEEW - R 2202 112
TABLE 1

INITIAL CONDITION'FOR EXPERIMENT LP.-SB-2 - RUN A

Parameter

Core AT

Hot leg press

Cold leg temp

Mass flow rate

Power level

TRAC

19.1

15.11

558.2

480.0

49.1

Plant

18.6 + 1.7 OK

14.95 + 0.11 MPa

557.2 + 1.5 *K

480.0 + 3.2 kg/sec

49.1 + 1.2 Mw

3.13 + 0.01 m

5.60 + 0.09 MPa

26.7 + 0.8 Kg

Steam Generator Secondary Side

Liquid level 3.13

Pressure 5.60

Steam mass flow 25.8

Pressurizer

Liquid volume

Water temp

Pressure

0.6462

615.3

15.09

0.6462 + 0.002 m3

615.8 + 8.2 *K

15.08 + 0.16 MPa

AEEW - R 2202 113
TABLE 2

OPERATION SET POINTS FOR EXPERIMENT LP-SB-2

Action Reference Plant TRAC

Small break

valve opened

time 0.0 0.0 secs

Reactor scrammed

Main feed water

shutoff

HPIS flow

initiated

Auxiliary

feedwater

initiated

Auxiliary

feedwater

terminated

Primary coolant

pump tripped off

intact loop hot

leg pressure

intact loop hot

leg pressure

intact loop hot

leg pressure

time after

reactor scram

time after

reactor scram

intact loop hot

leg pressure

14.28 14.28 MPa

14.28

8.07

62.0

1800.2

14.28 MPa

8.07 MPa

62.0 secs

1800.2 secs

3.161 3.161 MPa

AEEW - R 2202 114
TABLE 3

CERONOLOGY OF EVENTS FOR EXPERIMENT LP-SB-2 - RUN A

time after initiation

EVENT PLANT

Small break valve opened

Reactor scrammed

Main feedwater shutoff

Main steam control valve

started to close.

Main feedwater isolated

Main steam control valve

fully closed

HPIS initiated

Subcooled blowdown ended

Auxiliary feedwater

initiated

Pump two phase degradation

Indications of stratified flow

in the hot leg.

Collapsed level reaches break

level

Break started to uncover

Primary system pressure

became less than secondary

system pressure

Auxiliary feedwater shutoff

Inlet flow exceeded outlet flow

Primary coolant pumps tripped

(3.16 MPa in primary system)

0.0

1.8 ± 0.05

1.8 ± 0.2

2.8 ± 0.2

4.30 ± 0.05

14.8 ± 0.2

42.4 t 0.2

50.2 ± 1

63.8

582.2 ± 0.2

- 600.

- 1000. Wd)

1192.5 ± 2.5

1290.0 ± 45

1864.0 ± 0.2

2284.0 ± 200.

2852.8 ± 0.2

(seconds)

TRAC

0.0

2.31

2.31

3.4

4.14

80. (a)

41.3

53.3 (b)

64.3

590.0 (c)

1200.0

804.0

- 1920.

1307.

1864.

2059.

2635.

a) In the TRAC input deck the main steam control valve assumed the

function of the steam bypass control valve. Thus it kept on

moving up to 80 seconds when it was latched closed.

b) That value is such that 100 TSAT - = 0.1

TSAT

c) A smooth rather than'a sharp degradation was obtained

d) From Reference 9

AEEW - R 2202 115
TABLE 4

INSTRUMENT LOCATIONS FLOW AREAS

INSTRUMENT

LOFT

Flow Area

(M2 )

TRAC'

Flow Area

(M2 )

FE-lST-l and -2

ME-lST-l and -2

FE-5LP-1 and -2

ME-5LP-1 and -2

FE-5UP-i

ME-3UP-1 and -5UP-1

FE-PC-S03

ME-PC-S03

FE-PC-lA, -1B, and -IC

ME-PC-IA, -1B, and -IC

FE-PC-2A, -2B, and -2C

ME-PC-2A, -2B, and -2C

0.141

0.106

0.125

0.0007

0.0634

0.142

0.139

0.164

0.0634

AEEW - R 2202 116
TABLE 5

INITIAL CONDITIONS FOR EXPERIMENT LP-SB-2 RUN B

PARAMETER

Core AT

Hot"Leg Pressure

Cold Leg Temperature

Mass Flow Rate

Power Level

TRAC

19.1

15.11

558.1

480.0

49.1

PLANT

18.6 ± 1.70K

14.95 + 0.11 MPa

557.2 ± 1.5"K

480.0 ± 3.2 kg/s

49.1 Mw

3.13 ± 0.01 m

5.60 ± 0.05 MPa

26.7 ± 0.8 kg/s

Steam Generator Secondary Side

Liquid Level 3.13

Pressure 5.60

Steam-Mass Flow 25.8

Pressurizer

Liquid Volume

Water Temperature

Pressure

0.6462

615.3

15.09

0.6462 ± 0.0002 m3

615.8 ± 8.2*K

15.08 ± 0.16 MPa

AEEW - R 2202 117
TABLE 6

CHRONOLOGY OF EVENTS FOR EXPERIMENT LP-SB-2 RUN B

EVENT PLANT TRAC

Small Break Valve opened

Reactor scrammed

Main Feedwater shutoff

Main Steam control valve

started to close

Main feedwater isolated

Main steam control valve

fully closed

HPIS initiated

Subcooled blowdown ended

Auxiliary feedwater

initiated

Pumps two-phase

degradation

Indicators of

stratified flow in hot

leg

Stratified flow fully

developed

Break started to uncover

Primary system pressure

became less than

secondary system pressure

Auxiliary feedwater shutoff

Inlet flow exceeded outlet

flow

Primary coolant pumps

tripped (3.16 MPa

in primary system)

0.0

1.8 ± 0.05

1.8 ± 0.2

2.8 ± 0.2

4.3 ± 0.05

14.8 ± 0.2

42.4 ± 0.2

50.2 ± 1

63.8

582.2 ± 0.2

- 600

- 1200

1192.5 ± 2.5

1290.0 ± 4.5

1864.0 ± 0.2

2284 ± 200

2852.8 ± 0.2

0.0

1.93

1.93

2.92

3.7

80 (a)

54.51

70 (b)

69.3

522

- 700

- 1150

1175 (c)

1175

1864

1783

2706

(a) In the TRAC input deck the main steam control valve

assumed the function of the steam bypass control valve.

Thus it kept on moving up to 80 seconds when it was

latched closed.

(b) That value is

TSAT - T1

such that 100 = 0.1

TSAT

(c) Sudden change in depressurisation rate.

AEEW - R 2202 118
TABLE A.1

PUMP HEAD MULTIPLIERS RUN A

a

0.0

0.15

0.2125

0.3

0.33

0.4

0.5125

0.5825

0.712

0.8125

0.9125

0.9625

1.0

M( a)

0.0

0.14

0.202

0.346

0.519

0.712

0.702

0.769

0.769

0.731

0.558

0.25

0.0

The characteristic curves were those implemented in TRAC for

LOFT with the exception of the first quadrant of the fully

degraded curve that was made equal to zero.

AEEW - R 2202 119
TABLE A.2

PUMP HEAD MULTIPLIERS RUN B

PUMP 1

a

0.0

0.15

0.2125

0.3

0.34

0.35

0.5125

0.5825

0.712

0.8125

0.9125

0.9625

1.0

M(a)

0.0

0.14

0.202

0.346

0.519

0.9

0.9

0.9

0.9

0.9

0.558

0.25

0.0

PUMP 2

.a

0.0

0.15

0.2125

0.3

0.34

0.35

0.5125

0.5875

0.712

0.8125

0.9125

0.9625

1.0

M(a)

.0.0

0.14

0.202

0.346

0.519

0.712

0.739

0.769

0.769

0. 731

0.558

0.25

0.0

The characteristic curves were those implemented in TRAC for

LOFT with the exception of the first quadrant of the fully

degraded curve that was made equal to zero.

AEEW - R 2202 120
TABLE B.1

DESIRED BRANCH QUALITY VS VOID FRACTION

IN THE HOT LEG

a x

0.0 0.0

0.0115 0.0048

0.0676 0.0113

0.1221 0.0194

0.1943 0.0275

0.2654 0.0378

0.2799 0.0508

0.3084 0.0638

0.3524 0.0639

0.4 0.0680

0.43 0.0750

0.45 0.08

0.47 0.09

0.48 0.1040

0.666 0.15

0.75 0.9

AEEW - R 2202 121
t.

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TITLE OF FRAME,- LOFT SB-2 (RUN B) CORRELATED BREAK LINE QUALITY Ti 0.0

yLo[a -- 4

( 10.00)

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( 10.00)

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TITLE OF FRAME,- LOFT SB-2 (RUN B) CORRELATED BREAK LiNE QUAL[TY

I

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TITLE OF FRAMEs- LOFT SB-2 (RUN B) CORRELATED BREAK LINE QUALITY Ti 250.7

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( 10.00)

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TITLE OF FRAMEs- LOFT SB-2 (RUN B) CORRELATED BREAK LINE QUALITY

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TITLE OF FRAME,- LOFT SB-2 (RUN 0) CORRELATED BREAK LINE OUALITY Ti 451.0

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( 10.00)

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( 10.00)

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TITLE OF FRAMEs- LOFT SB-2 (RUN B) CORRELATED BREAK LINE QUALITY

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( 10.00)

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TITLE OF FRAMEr- LOFT SB-2 (RUN B) CORRELATED BREAK LINE QUALITY T i 652. 1

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I-.

S.M.A.R.T. SYSTEM MIMIC FOR ANALYSIS OF REACTOR TRANSIENTS

TITLE OF FRAME,- LOFT SB-2 (RUN B) CORRELATED BREAK LINE QUALITY TI 860.8

VL I -- +

( 10.00)

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10.00)

VOID FRACTION

0.88...

€=.. oa?67

:< " . 667.• .. +:
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I'.

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(Ai

Ti 961.7

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1 10.00)

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( 10.001

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• m 0.889..

0. 6..

ml~
tzj

IC%)

WWA

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TITLE OF FRAME,- LOFT SB-2 (RUN B)'CORRELATED BREAK LINE QUALITY Ti 1063.2

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( 10.00)

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0<o O. 889.

':'.ii. 0 778:. i 

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TITLE OF FRAMEs- LOFT SB-2 (RUN B) CORRELATED BREAK LINE QUALITY Ti 1164.4

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( 10.00)

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"-.0, 889..

<.= 0:" "778-

i.!.{i-. 0 ::.66?•
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I-,

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-J

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( 10.00)

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( 10.00)

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0., o889

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0>

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votD FRAcrio

<. 0..889.

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t~1

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S.11. A. R.T. SYSTEM MIMIC FOR ANALYSIS OF REACTOR TRANSIENTS

TITLE OF FRAMEIe- LOFT SO-2 (RUN 8) CORRELATEO BREAK LINE QUALITY

tJ

0

t'3

I-.

I.-.

Ti 2060.4

VLI -bi+

( 10.00

(10. 001

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TITLE OF FRAMEs- LOFT SB-2 (RUN B) CORRELATED BREAK LINE OUALITY

0

Ti 2261.4

VL I a -

( 10.00)

VYAP

(10.00)

VOID FRACTION

.4,

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i+
S. M.A.R. T- SYSTEM MIMIC FOR ANALYSIS OF REACTOR TRANSIENTS

TITLE OF FRAMEs- LOFT SB-2 (RUN B) CORRELATED BREAK LINE QUALITY

:z1

N

N

0

N

Ti 2462.7

VLIO -- +

(10.00)

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( 10.001

veoI FNDWTION
S.M.A.R.T. SYSTEM MIMIC FOR ANALYSIS OF REACTOR TRANSIENTS

TITLE OF FRAMEs- LOFT SB-2 (RUN B) CORRELATED BREAK LINE QUALITY

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0

z~J

'-a

.i~.

T i 2663. 7

( 10.00)

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S.M.A.R.T. SYSTEM MIMIC FOR ANALYSIS OF REACTOR TRANSIENTS

I" TITLE OF FRAME,- LOFT SB-2 (RUN B) CORRELATED BREAK LINE QUALITY

Ibi

T i 2764. 2.

VLII --

10.00)

VIAP 0-+

( 10.00)

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I:P

tri

to)

C.)

K3I

01t

S.M.A.R.T. SYSTEM MIMIC FOR ANALYSIS OF REACTOR TRANSIENTS

TITLE OF FRAME,- LOFT SB-2 (RUN B) CORRELATED BREAK LINE QUALITY Ti 2864. 5

(1 0.00)

VVAP

(1 0.00)

VOID r~Acrrw~

~. 0.889

~c- 0.718

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'a &66T
t:I

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TITLE OF FRAMEs- LOFT SB-2 (RUN 8) CORRELATED BREAK L[NE QUAL[TY T i 3085. 3

( 10.00)

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1 I0.00)

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VOID FRACTION
APPENDIX A

RUN B SNAPSHOTS AT SELECTED TIMES

A set of 26 snapshots describing the evolution of liquid and

steam velocites, fluid density and stratified flow conditions

for Run B is shown.

The nodalization can be compared with that used for Run A

(Fig 3). In the breakline the quality control valve has been

attached. Components 79 and 83 (vessel) are not included in

the snapshots frame.

AEEW - R 2202 148
APPENDIX B

MODIFICATIONS IMPLEMENTED IN TRAC-PFl/MODl WINFRITH

VERSIONS BO2A AND BO2C

IDE B001

Identify Version. Change this ident for each change in a

version.

IDE B002

Correct core treatment in vessel.

Insert return in bits suite of subroutines.

IDE B003 B02C only

Reset limit on stratified flow to 30 degrees

(ie ARCSIN(0.5))

COM WINF

This com deck contains the new Winfrith namelist variable

triggers

COM WINC

This com deck contains the stratified volume flag and

variables for the condensation heat transfer mod

IDE W003

Option to bypass interface sharpener routines while leaving

the fine mesh switched on. See also W007 for changes to

namelist option.

AEEW - R 2202 149
IDE W004

Plug weighting in interphase condensation heat transfer no

longer applied in stratified flow.

IDE W005

Allow wall condensation heat transfer in horizontal pipes

IDE W006

Allows negative friction factors.

IDE W007

Namelist extensions for W003 mods and printing diagnostic

triggers.

IDE WOO8

Add stratified flow regime indicators for graphics. Add

simple stratified offtake model option for tee components.*

Add pointers for condensation heat transfer mod (W009).

* (Option not selected for calculation A).

IDE W009

Make liquid velocity used in interface condensation heat

transfer continuous with changing void fraction.

(Option rot'selected for these calculations).

IDE W010

Alternative form of void'fraction for flow regime selection.

(Option not selected for these calculations).

IDE W011

Mod to cure convergence problems in CHF use of secant

method.

AEEW - R 2202 150
IDE W012

Correct error in evaluation of Forslund and Rohsenow liquid

heat transfer coefficient.

IDE W013

Correction to stratified flow head term.

IDE W014

Correction to upper guess in subroutine CHF.

IDE W016

Corrects error for inflow from break when IVDV=O.

IDE W017

Correct unset value of joining cell flag in steam gen comp.

IDE W018

Attempt to make SS restart with pressurizer more smooth.

IDE W019 B02C only

Insert missing square root of pi in Taitel-Dukler stratified

flow test in subroutine FEMON.

AEEW - R 2202 151

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 instrctions on the reverse) NUREG/IA- 0019

2. TITLE AND SUBTITLE AEEW-R-2202

TRAC-PF1/MOD1 Post-Test Calculations of the OECD 3 DATE REPORT PUBLISHED

Loft Experiment LP-SB-2 - MONTH j YEAR

December 1990

4. FIN OR GRANT NUMBER

5. AUTHOR(S) 6. TYPE OF REPORT

F. Pelayo Technical

7. PERIOD COVERED (Inclusive Dates)

U. rDnrJnEI•I RImI. %J 'afl.anI T Ttfl fl I I•flP, F,qC KIIirl-~:( Q ~~....LU~L I I . :ae5J sf..e.s•- fl. ...: c U, flrnun t- V ... snu *- aneg -- ,arr .. .umm---ss,o.. gum ... sigaues , .. c....r..... ... r... ..

o. un~ll•i • runvblW i~w--i•J• l~ •u n~o it 1YR. provide Division, 0 fice or Regin, U.S. Nuclear Regulatroy Commission, andmailingaddress,*ifcontractorprovide, name and mailing address.)

United Kingdom Atomic Energy Authority

Atomic Energy Establishment, Winfrith

Dorchester Dorset DT2 BDH

United Kingdom

9. SPO NSO R ING OR GAN IZAT ION - N AM E A ND A DD R ESS (if NR, type "Sam as above"., if contractor Provide NRC Divison Office or Regon U.S Nuclear Regulatory Commisin.

and mailing addrest)

Office of Nuclear Regulatory Research

U. S. Nuclear Regulatory Commission

Washington, DC 20555

10. SUPPLEMENTARY NOTES

11. ABSTRACT (200 words or less)

An analysis of the OECD-LOFT-LP-SB-2 experiment making use of TRAC-PF1/MOD1 is

described in the report. LP-SB2 experiment studies the effect of a delayed pump

trip in a small break LOCA scenario with a 3 inches equivalent diameter break

in the hot leg of a commercial PWR operating at full power. The experiment

was performed on 14 July 1983 in the LOFT facility at the Idaho National

Engineering Laboratory under the auspices of the Organisation for Economic

Co-operation and Development (OECD). This analysis presents an evaluation

of the code capability in reproducing the complex phenomena which determined

the LP-SB-2 transient evolution. The analysis comprises the results obtained

from two different runs. The first run is described in detail analysing the

main variables over two time spans: short and longer term. Several conclusions

are drawn and then a second run testing some of these conclusions is shown.

12. KEY WORDS/DESCR:PTORS (List words or phrases that will assist researchers In locating the report.) 13. AVAILABILITY STATEMENT

Unlimited

TRAC-PFI, OECD LOFT, Small break 14. SECURITY CLASSIFICATION

(This Page)

Uncl assified (This Report)

Uncl assi fied

15. NUMBER OF PAGES

16. PRICE

NRC FORM 335 (289)


THIS DOCUMENT WAS PRINTED USING RECYCLED PAPER.

UNITED STATES

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U USNRC I

PERMIT No. G-67

Gene Rhee (4)

NLN-337