NUREG/IA-0013

SAgreement Intema-onalReport

RELAP5/MOD2 Calculation of

OECD-LOFT Test LP-SB-03

Prepared by

C. Harwood, G. Brown

Central Electricity Generating Board

Barnwood, Gloucester

GL4 7RS

United Kingdom

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

Washington, DC 20555

January 1990

Prepared as part of

The Agreement on Research Participation and Technical Exchange

under the International Thermal-Hydraullo Code'Assessment

and AppIcation Program (ICAP)

Published by

U.S. Nuclear Regulatory Commission
NOTICE

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

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

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by such third party Would not infringe privately owned rights.

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P.O. Box 37082

Washington, D.C. 20013-7082

and

National Technical Information Service

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NUREG/IA-0013

International

'J Agreement Report

RELAP5/MOD2 Calculation of

OECD-LOFT Test LP-SB-03

Prepared by

C. Harwood, G. Brown

Central Electricity Generating Board

Barnwood. Gloucester

GL4 7RS

United Kingdom

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

Washington, DC 20555

January 1990

Prepared ats part of

The Agreement on Research Participation and TeohnlcaJ Exchange

under the Internatlora Thermal-Hydrauufo Code Assessment

and App•atlon 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: This report compares the results of the RELAP5/MOD2 analysis with

experimental measurements.

A simulation of test LP-SB-03 was previously carried out at GDCD using the

RELAP5/MOD1 code. RELAP5/MOD2 was developed from RELAP5/MOD1 and contains

more sophisticated hydraulic models and constitutive relationships.

Comparison of the RELAP5/MOD2 and MODI calculations show that RELAP5/MOD2

performs better than RELAP5/MOD1 in a number of key areas; notably mass

errors are much reduced, there is improved numerical stability, and

improved separator modelling and modelling of accumulator injection.

iii

CONTENTS

ABSTRACT iMi

CONTENTS v

SUMMARY vii

1. INTRODUCTION 1

2. INPUT DATA AND MODEL 2

3. STEADY STATE AND NULL TRANSIENT 3

4. TRANSIENT 5

4.1 DESCRIPTION OF EXPERIM1ENTAL TRANSIENT 5

4.2 RELAP5/MOD2 RESULTS 5

4.3 COMPUTING TLME 8

5. DISCUSSION 8

6. CONCLUSION 10

REFERENCES 11

TABLES 12

LIST OF FIGURES 13

FIGURES

Microfiche of computer output has been filed under Safety Technology Section in

Microfiche Archive at Barnwood.

CWl 00 IR6KEL/GBI1

V.

Summry: In order to confirm the ability of RELAP5/MODZ to describe a small

break LOCA sequence in a PWR type geometry, analysis of test LP-SB-03

of the OECD LOFT experimental program has been carried out. Test LPSB-03 simulated a 0.4% cold leg break in a PWR, with failure of high

head safety injection; cooldown was achieved by feed and bleed of

the secondary side, some time after core uncovery.

This report compares the results of the RELAP5/MOD2 analysis with

experimental measurements.

A simulation of test LP-SB-03 was previously carried out at GDCD

using the RELAP5/51OD1 code. RELAP5/MOD2 was developed from

RELAP5/MODl and contains more sophisticated hydraulic models and

constitutive relationships. Comparison of the RELAP5/MOD2 and MOD1

calculations show that RELAP5/MOD2 performs better than RELAP5/MODI

in a number of key areas; notably mass errors are much reduced,

there is improved numerical stability, and improved separator

modelling and modelling of accumulator injection.

Overall agreement with experiment obtained using RELAP5/IOD2 is

excellent, with all key phenomena correctly predicted, in the correct

sequence with accurate timing. The CPU to real time ratio was

approximately 3.5:1 on the Harwell Cray-I computer.

Results of this calculation have been submitted to the OECD LOFT

program review group as the United Kingdom contribution to the

comparison report for test LP-SB-03.

vii

L. INTRODUCTION

Loss-of-coolant accident (LOCA) analyses for the Sizewell 'B' PreOperational Safety Report (POSR) are expected to be carried out mainly

using proprietary Westinghouse computer codes. In order to assess the

POSR calculations, and develop a CEGB capability for LOCA analysis for

operating ?;Rs, GDCD is carrying out independent calculations of limiting

LOCA sequences using computer codes accessible to CEGB. The assessment is

being carried out at the request of N.T.

The RELAP5/MOD2 code [4] is presently being used by GDCD for calculating

small-break LOCA (SBLOCA) sequences for Sizewell 'B' [5]. RELAP5/MOD2

uses a six-equation two fluid model to describe two-phase flow in the

reactor primary and secondary systems. It supersedes the RELAP5/MODl code,

which employed a five-equation two-phase flow model (one phase constrained

to thermal equilibrium) and used less sophisticated models for flow regime

transitions and interphase interaction terms.

To gain experience with using RELAP5/MOD2, the code was used to simulate

SBLOCA test LP-SB-03 carried out in the LOFT experimental reactor [2, 3]

under the OECD LOFT programme. An analysis of this experiment was

previously carried out by GDCD using RELAP5/MODI [1].

LOFT test LP-SB-03 simulated a 0.4% cold leg break in a PWR with no highhead injection. As noted in [1] the experiment provides a severe test of

a reactor analysis code since a wide-range of complex phenomena which

occur in a reactor SBLOCA must be simulated, including:

(1) Steam generator heat transfer in forced circulation, natural

circulation and reflux condensation mode;

(2) Core heat transfer for uncovered core conditions;

(3) Single and two-phase critical discharge flow;

(4) Two-phase pump head degradation;

(5) Accumulator injection.

The present report discusses the RELAP5/,OD2 analysis of test LP-SB-03, in

detail. The results of the present calculation have been submitted to the

OECD LOFT program review group as the United Kingdom contribution to the

comparison report for test LP-SB-03.

GDCD is in the process of performing analyses of hot-leg break tests LPSB-01 and LP-SB-02 carried out in the same series, and these will be

reported subsequently.

1.
2. INPUT DATA AND MODEL

The input data were based on the INEL deck used for the pre-test

prediction, and for the RELAPS/MOD. calculation reported previously (1].

The modified noding scheme employed (figure 26) included a number of

changes to ensure compatibility with RELAP5/MOD2. These changes were:-

(1) Changes to both the inlet and outlet plenum models. In (I] the

inlet plenum (upper downcomer) was divided laterally and vertically

into four volumes. For the present calculation it was remodelled

as an annular downcomer in three levels, with the cold legs

connected to the central volume. The outlet plenum was changed

from two vertically stacked cylindrical volumes to three to comply

with the format of the inlet plenum. This nodalisation was adopted

to. comply with EG&G recommendations for use of RELAP5/MOD2 with the

cross flow junction option [4].

(2) The connection between the cold leg and the break discharge line

was modelled as a tee using a centrally located cross flow

junction.

(3) In accordance with EG&G guidelines, junctions at the reactor

pressure vessel (RPV) nozzles, the break line connection to the

cold leg, and the pressuriser surge line connection to the hot leg

were all treated as cross-flow junctions. In these junctions the

momentum flux terms are deleted from the momentum conservation

equations used to calculate junction flow.

(4) Junction Options: The MOD2 version of RELAP5 has a new option

by which the junction inlet void fraction can be corrected to allow

for flow stratification in the upstream volume. Separate models

for a centrally located junction; upward Oriented junction,

downward oriented junction are available. In accordance with EG&G

guidelines, this option with the centrally located junction model

was invoked for all connections between horizontal pipes.

(5) Volume Options: The new boron transport model and facility to

include fluids other than water were not employed. Other changes

were needed in specifying initial conditions consistent with the 6

equation formulation.

The calculation was perfbrmed on the Harwell Cray-I computer using

RELAP5/MOD2/CYCLE 36.01 incorporating corrections to Cray

conversion errors implemented by UKAEA Winfrith. An error that was

identified but not corrected was that the code failed to utilise

the horizontal stratification model at the junction between the

break line and the cold leg. (see (4) above). It was discovered

that code cycle 36.01 did not employ this model in a cross-flow

junction due to a coding error. This error has subsequently been

corrected and the horizontal stratification model is working

correctly in cycle 36.02. The impact of this error on the present

calculation is thought to be small and is discussed in section 4.2

.(b).

2.
3. STEADY STATE AND NULL TRANSIENT

RELAP5 does not solve steady state equations hence the code must be run in

transient mode until stable conditions are achieved. This process is

accelerated in RELAP5/A1OD2 by use of a 'steady state' option in which the

thermal inertia of heat structures are set to artificially low values.

The steady state option also checks for convergence of a steady state.

Key parameters were controlled using RELAP5 control variables to provide

the necessary feed back, to achieve the required steady state. Parameters

controlled in this analysis were Pressuriser Pressure, Primary Mass Flow

Rate, Secondary Pressure and SG downcomer water level. Calculation of

steady state conditions is discussed below and illustrated in Figures 1-8.

The experimental values at the start of the transient have been added to

the graphs, where- available, together with error bars.

Pressuriser pressure was set by attaching a fictitious RELAP5 time

dependent volume to the steam space of the pressuriser. The dummy volume

was assuned. filled with saturated steam at the desired pressure (15.26

HPa). Pressuriser level was not adjusted as the final value fell within

the experimental uncertainty range. Primary pressure in the steady state

run is shown in figure 1; pressuriser level and surge line flow in

figure 5.

Primary loop flow was adjusted by using a proportional/integral controller

(based on loop flow error) to control pump speed. Active loop mass flow

in the steady state run is shown in .figure 2; inactive loop mass flow is

shown in figure 3.

Secondary side pressure (and hence primary side temperature) was

controlled by a proportional/integral control system (based on SG Dome

pressure error) operating on the main steam control valve. Hot and cold

leg temperatures in the steady state run are shown in figure 4.

Steam Generator downcomer collapsed liquid level was controlled by

adjusting feed flow. Feed flow was set equal to steam flow plus a term

proportional to the SG level error. The SG level was set higher than the

measured value, as at lower levels, steam entrainment was found to occur

in the SG separator component leading to an erroneous prediction of

voiding in the downcomer. Various steam generator parameters in the

steady state run are shown in figures 6-8.

It is seen that there is. no evidence of the oscillations in the stefm

generator recirculation flow that appeared in the calculation of reference

[1.

RELAP5/MOD2 calculated that a stable steady state was achieved at 78.9s.

In order to check the stability of the converged steady state a null

transient was run in which the steady state controls were removed and

break flow and pump seal injection flow were set to zero. Apart from an

anticipated decay in pressure due to pressuriser heat losses (the

pressuriser heaters played an insignificant role in this test, and were

omitted from the model) the calculated plant state was stable. Conditions

after 15.7s of null transient were judged acceptably close to initial

experimental conditions and the transient was initiated from this point.

3.
Table 1 shows a comparison with the initial conditions measured in the

experiment and those used in the calculation. Also shown are the initial

conditions used for the RELAP5/WODI calculation reference [1]. The only

significant discrepancy is the water level in the SG downcomer which, as

noted above, was made artificially high in the RELAP5/MOD2 calculation in

order to avoid steam being entrained into the! lower SG downcomer.

4.
4. TRANSIENT

,4.1 DESCRIPTION OF EXPERIMA.ENTAL TRANSIENT

In the experimental data report (31 the LP-SB-03 transient is

divided into four distinct stages where different phenomena occur.

These are as follows:-

(a) Rapid mass depletion phase. This is the period between

break opening and pump trip at 1600s. During this phase the

flow is a well mixed two phase flow and mass loss is

relatively rapid. The break does not remove sufficient

enthalpy to overcome decay heat and some enthalpy is

consequently rejected via fluid discharge from the SG •ain

Steam Control Value (MSCV).

(b) Boildown phase. This period occurs after pump trip at 1600s

(when primary system mass is reduced to about 50%) when the

remaining liquid falls to the lowest points in the circuit,

the RPV and loop seals. The break flow transitions to a

high quality steam flow, leading to a lower rate of removal

of mass; however the rate of removal of enthalpy is now

sufficient to give primary depressurisation. Heat transfer

from the primary to the secondary continues to be in the

forward direction because of steam leakage from the SG MSCV.

The core drys out and the break is isolated during this

phase. Forward SG heat transfer is also lost.

(c) Cooldown by secondary feed and bleed. This phase began when

the operator reintroduced SG feed and opened a SG relief

valve at t- 5415s. This action was initiated after clad

temperature had reached 977K in the reactor core. Forward

heat transfer is restored in the SG and the primary pressure

falls rapidly.

(d) Accumulator and LPIS injection. This phase occurs after t5800s, after primary pressure falls below the accumulator

set point. Accumulator and Low Pressure Injection System

(LPIS) flow rewets the core and refills the primary system.

4.2 RELAP5/HOD2 RESULTS

Results of the transients calculations are compared with data in

figures 9-25. In these plots, time zero refers to the time of.

opening of the break valve. Table 2 shows the timing of key events

in the test and in the calculation.

(a) Primary-Secondary Pressure. Primary and secondary side

pressures are plotted in figures 12 and 13. Agreement with

measurement is seen to be very good.

5.
In the period before pump trip, calculated to occur at t1660s the break nozzle discharges a low quality two phase

mixture, resulting in a relatively low enthalpy discharge

rate. Consequently, the pressure tends to rise, causing

periodic cycling of the main steam control valve (MSCV) on

the Steam Generator. The cycling of the valve is correctly

predicted by the code, though RELAP5 predicted 2 cycles

instead of the 4 measured. (Note that in the test the MSCV

failed to completely reseat leading to an estimated leakage

of 0.13 kg/s [3]. This leakage rate was simulated in the

RELAP5/M!D2 analysis by using an appropriate minimum valve

flow area.)

After pump trip at t- 1660s the break discharges high

quality steam, leading to a steady depressurisation of the

primary and secondary systems which is well represented by

RELAP5/HOD2. At about 4500s primary pressure is calculated

to fall below secondary pressure (figure 11) owing to

reduced heat input from the core which began to uncover at

4300s. This is in good agreement with the measurement

(figures 12 and 13). There is experimental evidence that

reflux condensation continued even after primary pressure

fell below secondary pressure [1]. However RELAP5/MOD2

failed to predict this behaviour. The pressure levels out

after break isolation, and then falls rapidly after

initiation of secondary side bleed and feed. (t- 5415s in

experiment, t- 5308s in RELAPS simulation). Bleed and feed

was initiated manually by the operator after peak clad

temperatures exceeded 977K. The depressurisation during the

bleed and feed phase is seen to be well represented by

RELAP5. Accumulator injection occurs at 5501s when the set

point of 2.84 MPa is reached. The reduction in

depressurisation rate is due to steam formation as the core

is rewetted.

(b) Break mass flow rate and Drimary inventory. The measured

and calculated break flows, and the measured and calculated

primary inventory are shown in figures 9 and 10. Agreement

is seen to be extremely good.

The sharp drop in calculated break mass flow rate at t-1660

is associated with pump trip, which results in break-down of

forced circulation and emptying of the cold leg pipework.

The transition from two-phase conditions to high quality

steam conditions in the cold leg causes the discharge flow

to drop sharply. The magnitude of the flow rate reduction

is seen to be well predicted by RELAP5/MOD2. In section 2

it was indicated that a code error prevented the horizontal

stratification model from being used in a cross flow

junction. This caused the break line junction to the cold

leg to use average upstream conditions even when the cold

leg was stratified. However, this error was considered

insignificant as the cold leg drained rapidly after pump

trip hence the potential mass flow error was small. The

calculated primary inventory agrees well with measurement up

to 6100s after which the ECCS injection is overpredicted, as

shown in figure 25.

6.
(c) Fluid Densities in Primary Pipework. Measured and

predicted fluid densities in the cold..leg.and hot leg

pipework and in the break discharge pipe are shown in

figures 14 to 16. Agreement between measured and calculated

values is seen to be good. After pump trip the hot leg

density shows a sudden fall, followed by a recovery. This

behaviour is believed due to the fact that when forced

circulation ceases, the fluid in the hot leg drains back

into the pressure vessel; water held up in the steam

generator then drain3 downwards causing a partial refilling

of the hot leg and loop seal downside. This behaviour is

seen to be reproduced remarkably well by the RELAP5

calculation (see figures 16 and 17).

(d) Clad Temneratures. Fuel cladding temperatures at the

elevations corresponding to the centres of the six RELAP5

core nodes are shown in figures 18 to 23. The timing of

core uncovery is seen to be captured quite well by the

RELAP5 calculation, with the rate of progress of the dryout

front very well predicted. There is a tendency for RELAP5

to over-predict heat up of fuel in the lower part of the

core and to underpredict the heat-up at the top of the core.

This tendency was also.seen in the RELAP5/MODI calculation

reported in [1]. It was suggested in [1] that the effect

was caused by the return of condensed water from the SG. In

the calculation the water falls on the top core node and

enhances cooling there. It is believed that in the

experiment the water ran down the core periphery and was

boiled off at the dryout front, contributing to heat

transfer throughout the dry part of the core. A multiple

channel core model would probably be required to correctly

represent core heat transfer under these conditions.

Following feed and bleed initiation RELAP5 correctly

predicts the rewetting of the second core slab (figure 19)

but over predicts the cooling of the core particularly at

the top (for similar reasons to those described above for

the high heatup rate). The code then correctly predicts a

second dryout of second core slab followed by rewetting of

the whole core, from below, after accumulator injection.

(e) Accumulator Injection and Core Rewetting. Accumulator

injection commenced at t- 5538s in the experiment and at t5501s in the RELAP5 simulation. Injection was initiated

when the primary system pressure fell to the set-point

pressure of 2.84 MPa.

The measured and calculated accumulator flows are shown in

figure 24. The calculated accumulator flow is highly

oscillatory, although the oscillations did not lead to

termination of the calculation, as occurred in the analysis

of [1]. The calculated mean injection flow-rate is

considerably higher than the measured value in the later

part of the transient. This appears to be due to an overprediction of the rate of steam condensation in the injected

water, which leads to a calculated primary system

depressurisation rate which is higher than that observed.

Accumulator level is shown in figure 25.

7.
4.3 COMPUTING TDIE

The total problem time simulated was 7009s. The maximum and

minimum time-step sizes were 0.1 and 10- s respectively. The rate

of CPU time to problem time was 3.5 on the Harwell Cray-I

computer.

5. DISCUSSION

In this section the RELAP5/MOD2 calculation is compared with the

RELAP5/XODI analysis discussed in [1]. There were seven areas identified

in [1] where RELAPh/MODI. did not perform well. Here each area is examined

in turn to determine whether or not the new code RELAP5/XOD2 produces

improved results.

(a) Steam Generator Separator

In the RELAPh/XODI calculation in reference [1] a mass/energy

conservation error occurred in the SG separator/lower separator

region. To alleviate this problem the junction between the lower

separator and the separator bypass was disconnected. This course

of action was not found to be necessary in the MOD2 calculation.

It was found, however, that in order to maintain the desired

separator level it was necessary to increase the downcomer level

arbitrarily, from the measured value of 3.16m, to 3.7m. Discussion

with the code developers suggests that the desired result could

also have been achieved by adjusting loss coefficients and friction

factors.

(b) Mass Errors

At the end of the transient the mass error was approximately 12 kg

which is 0.87% of the minimum inventory. This is a negligible

error and is a major improvement over the MODI calculation where

mass errors reached 100 kg.

(c) Steam Generator Level Oscillations

As in the MODI calculation, oscillations were observed in the SG

level throughout the transient. In the MOD2 calculation, the

oscillations are present but are of much reduced amplitude.

(d) Accumulator Injection

As in the RELAP5I/1ODJ calculation the accumulator injection flowrate was calculated to be more oscillatory than measured.

Eventually the oscillations caused a water property error which

led to the termination of the calculation. The RELAP5/MOD2

calculation did not terminate in the accumulator injection phase.

(e) Water Distribution and Inventory

RELAP5/MOD2.predicted fluid densities well; the problem identified

with the RELAP5/MODl code in which water was predicted to rise

faster than steam in the core outlet region, was not seen in the

new calculation. The calculated primary inventory was in excellent

agreement with the experiment, and showed a marked improvement on

the MODI calculation. (see figure 9).

8.
(f) Steam.Generator Heat Transfer

As found with the MODI analysis, RELAP5/',OD2 calculated low SG heat

transfer in steady state, and once again failed to predict the

complex effects thought to be present after core dry out i.e.

continued reflux condensation when primary pressure is below

secondary pressure. It is possible that inclusion of a small node

at the bottom of the SG riser would enable the code to model this

behaviour. The code did however go on to predict restoration of

reflux cooling and the feed and bleed phase, reasonably well.

(g) Core Heat Transfer

As with the RELAP5/MOD1 calculation, RELAP5/MOD2 underpredicted core heat transfer after dryout and predicted a more

rapid quench than measured. In section 4.2(d) it is argued that a

multi-channel core representation would be required to permit the

code to adequately model these effects.

9.
6. CONCLUSIONS

This report describes a RELAP5/iOD2 calculation of LOFT test LP-SB-03,

which simulated a 0.4% cold leg loss of coolant accident (LOCA) in a PWR.

RELAP5/X.OD2 calculated all the thermal-hydraulic phenomena exhibited in

the test, in the correct order and with reasonable timing. No

discrepancies were seen in this analysis which are expected to be of

significance for reactor small break LOCA calculations.

RELAP5/MOD2 performed better than the RELAP5/MODI code which was

previously used by GDCD for analysis of this test. In particular

RELAP5/MOD2 was found to be more stable and robust, with an improved

numerical solution scheme removing the mass error problems encountered in

the earlier code version.

The present calculation was submitted to the OECD LOFT program review

group as the United Kingdom contribution to the code comparison report for

test LP-SB-03. It will also form part of a validation report to

underwrite use of RELAP5/MOD2 by GDCD for analysing Sizewell 'B' small

break LOCA sequences.

10.
REFERENCES

I . GD/PE-N/482 Post test analysis of OECD LOFT

experiment LP-SB-03 using

RELAPS/MODI. Volume 1 Analysis,

Volume 2 Figures.

C Harwood Feb. 1985

2. OECD LOFT-T-3603 Best estimate prediction for OECD

LOFT project small cold leg break

experiment LP-SB-03

W H Grush, H Tanaka, P Marsili

Quick Look report on OECD LOFT

experiment LP-SB-03

H Tanaka et al.

Feb. 1984

3. OECD LOFT-T-3604

4. NUREG/CR-4312

EGG-2396

Mar. 1984

RELAP5/M0D2 Code Manual

Vols. 1 and 2

V H Ransom et al. Apr. 1984

5. RELAP5/MOD2 input data deck for

Sizewell 'B'

C Harwood

C~J11OO1R6KEL/GB1

11.
Table I

Comoarison of RELAP Steady State

for MODI and MOD2 with measured Data

II Variable 'Units' Measured MOD2 2 MOD i

I

IPrimary

IPressuriser pressure

IPower

lIntact loop mass flow

IPressuriser level

ICold leg temperature

[Hot leg temperature

ISecondary

IPressure

ILevel

ISteam Flow

IPa

114W

IKg/s

Im

oK

I K

1 MPa

Im

IKg/s I

15.26 + .11 15.30 15.26

50.3 +1.2 50.0 50.0

1482.6 + 2.6 1 482.6 482.6

1 1.115+ .06 1 1.0893 1.097

1556.4 1 557.81 557.6

1576.4 + 1 1 577.06 576.9

1 5.58+ .06 1 5.47 5.43

1 3.16+ .02 3.704 3.114

26.67T .77 26.19 26.32

I _ _ _ _ I_ _ _ _ _ I_ _ _ _

Table 2

Timing of key events

Event

IBreak opened

IScram

IPrimary coolant pump trip

IStart of core heatup

IBreak isolated

ISG feed and bleed initiated

lAccumulator injection

ICore quenched

ILPIS I

I Measured I MOD2 MODM [(1]

time (s) time (s) time (s)

0 0 0

9.21 + .011 11.525 10.6

11600 +2 11660 1565

13800 • 50 *I 4385 3800

14742 T 2 15085 4627

15415 + 5 15308 4878

15558 + 3 15501 5099

15800 + 50 I 5650 5200

16785 +2 16285 I II

12.

C,11001.R6KEL/GB1.
LIST OF FIGLRES

.Steady State RELAP5 Results

1.

2.

3.

4.

5.

6.

7.

8.

Primary Pressure

Active loop mass flow

Inactive loop mass flow

Hot and cold leg coolant temperatures

Pressuriser level and surge line flow

Steam generator level and pressure

Steam generator steam and feed flow

SG separator steam, liquid return, and mixture inlet flows

Transient Comparison of RELAP5 with experiment

9. Primary system coolant inventory

10. Break flow

11. Primary and Secondary pressure (RELAP)

12.

13.

14.

15.

16

17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

Primary pressure

Secondary pressure

Break line density

Cold leg density

Hot leg density

Loop seal downside d

Clad temperature

Clad temperature

Clad temperature

Clad temperature

Clad temperature

Clad temperature

Accumulator flow

Accumulator level

RELAP5 noding scheme

ensity

O.14m

0.42m

0. 70m

0.98m

1.26m

1.59m

0 - 7000s

0 - 7000s

0 - 7000s

0 - 7000s

0 - 7000s

0 - 7000s

0 - 7000s

0 - 7000s

0 - 7000s

3500 - 7000s

3500 - 7000s

3500 - 7000s

3500 - 7000s

3500 - 7000s

3500 - 7000s

5000 - 7000s

5000 - 7000s

level

level

level

level

level

level

(based on figure 1 of

reference 2)

CW1d100LR6aL/G3l

13.
FIGURE I FIGURE 1LP-SB-03 RELAP5/MOD2 sAcadU 3taita calculation.

15.4-

14.8-

14.6-

................ .............. ............... O.............. .. .. .. . .. ..... .. o...................... ....-........

............... ................ ooooo~. o o oooooo.oo . ...... . ... ooo.. o........ -o o.............o .ooooooe.......... o.................. .................... o~oooo~oo

PRESSURI (EXPERIMIE I.......

...

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

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

I................

....... I...........

.-.................. I

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

tt

..- ............... -............................. .................. .............. o.............

Tis

____ ___ ___ __ ___ __ _____ __ ___ _ _ ____ _ 1810Ti. _______ .. . I_______ I ____ _____ ________________

15.4

T)

-15.a

14.8

-14.6

(5)

RELAP MIodel

Primary pro33ura.
FIGuRE a LP-SB-03 RELAPS/IOD2 atoadUj st.ate .alculaton.

4945. ................ ........... ............ ............... . . . I8

48 ................. ................ I j .............. ................ ............................... t ................ .8........4...... "

483 .......... ................ I ................ !. ......................... t...................................................! ................ !. .......... -u48 iI I I ,

4 a ........ ........ ,...... ......... i ................ ............... ÷ ....... ...................... •............... ................ i ...... ......... i ....... ........ .482

3- ..................................-.................................................... .... ... o 

................. ................ 47 .......................... ....... ................-.......... 7..... 9

I.... tI I

47 .............. ................ ............... ................ iI . ................ ................ t ................ I................ I ................ I.......... o..... .-478 I.........7 I 

3........7

4.................. ............... ......................................................... .. ..... ....... ........................... .47

476.. .................................. ..... ....... ............... -476

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

1 1

201 40 s0 so 11167

RELAP TiFLO4JIBODI

Active loop mass flou.
FIGURE 3 FIGURE 3LP;-SIJ-03 RELAPS/MOD2 sAaidU 3tate catcutaLion.

i i .4 1 i -* ft 7.4-

72-

7.6-,

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

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

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

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

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

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

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

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

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

-7.6

-7.4

-7.2*

-7.8

-6.8

6.6

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

6.18-

6.6- ................ ................ ................

I * .I

2.0 40 68 sI II

Time is)

RELAP

IiFLOUJ37S"

Inactiva loop *t38 (tow1.
FIGURE 4 FIGURE 4LP-SB-03 RELAPS/PIOD2 steadU state calculation.

see- .................,................................o................. ................o ................o ................ -..................................

. .... .

.o.ooo.to.I. o--oI-oo--,,.....~.*.....o ....... ....ooo. ,~eeo~o~~io.o.oo~4.*..•e~o

600

590.-1............. I 69e

[80- .............. . . . . ..-. " " "'""'"..- .........

1. 1 4 4 1- i-I

570

566-

55,_

!

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

I ........ ........

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

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

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

............ O1T LEG...

iWPERII¶ENT

6OLD LEG

......... i........

so$

5S7

-560

................ ................ -50

1.4I 0- -t . 4-

213 40 61) ieO ISOj

Tine (a)

RELAP REL(.P

TEI¶P19881 - M~prmei .....

Hot and cold log coolant temperatures.
FIGURE 6

E13

FIGURE 5LP-SB-03 RELAPS/IlODB attnd~g Antea calculat~ion. rIa3

-f 8,1

a

I * a.-

'I

I

I

1.Ib-

.............. ............................. !................. ............... ............... ............... i ............... i ...............

.~......................... 1 f PRESqURISER LEI

PIS

.........

.........

-1.8

EL

.. ...... ..

.............. I

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

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

..........

............... s6. 

I

*

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

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

............................................ *............. : :... ....... e.0.

: !.-

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

I I*.°.°**

-O.S

1.0,-

ife I

40 30

limo (a)

REt-hP RELAP

CHTRLUAR2 C13 - NFLOWJ48001 C23]....

Pressurisor level and surge line flow.
FIGUREr;

4.•

3.8-

-3.4-

3.2-

6

13

LP-SB-03 RELAPS/hOD2 tLamdg ALuat calculation.

Cal

.............. .... o.. ..... ............. o .............. -.. .. -...... - .. o.ooo...... 

.oo..... .. ..... .. .I.. oe.. ... 1.-. ..... ... . . ... .. .. . ... ...

...........

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

...........

ODJq.... .... ...... ; r- , 4. ~ 4 p. ....

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

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

: J

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

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

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

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

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

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

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

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

....... I .......

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

............... I

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

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

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

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

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

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

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

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

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

.........

p s

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

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

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

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

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

LEVEL

EXPERM

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

.HtI.....

T......o... .-.........

.. *.o.......

L.o..o......

.3

.... 5.

.3 ..- 5.41

its 5.0

TIm

Tame *8)

I-We 4 .__ _ _

20 48 69

tuAI (3 - M Cal (........

Steam generator level and pre3sure.

soI
FIGURE 7 FIGURE 7LP-SB-03 RELAPS/110D2 3tondq st.ate calculatLon.

36-

2a-

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

-3,

-as

EXPERMlE

°..o.ee........

IT

26-f

124- ................ .................................................. I ................................................................. I ................ I ................. 1

2a -1l ......... ........ I.........

2e- ................. .................

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

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

......... I ........ 4 .............. ...................... ......... Iaa

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

I Z JU

IW ai2 I4I) 60 BeI ISOa--

Time (a)

AP

Steam generator ateam and food ftow.
FIGUE

280-1.

aI I ~LP-SD-83 RELAP541ODi2 stoadU staite catculation.

OA I.................................. .... ................................. ................

,°°....°°. ........ °.. ..... . .. . . .....

150-

I'0

'leaI

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

8S

-158

-iso

. ... M.- &I ,*! 1!1*f=**=ll*= - -.-. .- o -- 'r- - . . ........

1

. .... ......

.. . .... .

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

. Z

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

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

Z

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

DW- . ...... • ......... ................ ............... i........... .•................ :................................. 1................ :.............. ................ .Do

U....... ........... S,. .. rnvm P. 3j ............. M .......1[ .................. .......T.

I 48 6o Ho

Time Is)

RFLP -Gto o.l tUJSOOt3

SG scoarator steam, liquid return, and mixture inlet flows.
LOFT TEST LP-SB-03, COMPARISON OF RELAPS/MOD2/CY36,01 UITH EXPERIMENT

5500-

5000-

4S0-0

3000- 2508-

1500-i

.°.°.°....

. .... 

. . .

i .. 

. .. 

.. °........

S...........

o..... .....

...........

!...........

I.

.LWP.. frUIIP RIP..LEJ RmEIImt RIP (RL(P I

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

...........

...........

°.......... ...,........

.°°......... .°°.......

.I.

...........

...........

...........

...........

...........

°°. .. °o °°,°...... ..

........... !..........

.I.

°° .....

............ E -. I0 IIj0 ..(EX PEAK ISOLATI( .~ 

...........

.............. I... ... ...2 .....

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

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

.............. I... . .

* a A ... ... V..... ... .. ... ..

rl (RELAP)

I RE LAP4

li (EXPEf1MEHT)

.. ..2 .. ....

......

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

..... .. . '....

.. . .. . .. . .

-5508

.5000

-4508

-4000

-3500

-300•

-2500

12001

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

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

-t T

2000 I 20080 I

RELAP EXPERIHENT

CIaTRLUAR?2 - PCS-IHASS ........

FIGAIRE 9 Pa

1 3008 I 400.3 5030 6000

Tine Is)

aiauarU s 1 j~Lem coolanL Inventoru.
LOFT TEST LP-SB-03, COMPARISON OF RELAPS/lOD2/CY36.e1 UITH EXPERIMENT.

i I j .... .... ,..... ........ a7-

6

4-

3-

~.... ..

...... 

.....

m.MD~b............

6. . S~~.f~ ..... . ....... I .. ... ...1.. ...... .•. ......... ........... ,......

I.i .. .. -........... . .. .. :........... ............

I ...............

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

. . . . .I .

...... I. ...... i....... i............ I......... .

I I

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* I

8 1. . ,

I I I

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o it -I

RUE A..MSLATjLOII..REIA;P.1 .......... r REAK ISOLATION (EXPERII¶EK)T

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

1 SOrI t1.1 i×tR~ltl

/. .i.......

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

* I

............. ...... .......... .. I ...... . I . .

.. .. .. . . . . . .!. . .. . . I.. . . . . . ............

S ..... . . .. .. .. -I,. . . . . . . . . . . .: .. . . . . .. .

I :1

-I

I I -

eteco 2000

RELAP EXPERIFIEIIT

ttFLOUJI8360 - FR-PC-DPK .....

FIGURE 10

3O06O 40

i0

Time

Break (lo&u.
UISION REFERENCE FILE LP-SS-3ILOFTII

LOFT TEST LP-SB-03, RELAPS/4OD2/CY36-.1 RESULTS.

16 . ............. :............ ........................ ............. :............ ............... " ............ "............................................................ ........... . r'16

........... ............ ...... .. ...... .. 4

84 .... •....... ......................... ........... .................................... .................................................. * ........... ....... '"•................ 1

. ..... , ..o .. ...... o .. .oo .. oo.... ... . ......... o... .... o. o... ... ..... .. , ..... ... oe .... o..o............o......... ... o . ...... o .. o.. •.o.I.... ... ......... ...... .. •..o..........

.I.

... .. . . .. . . . .. . . ..... ... .. •. . . . . .

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

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

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

: PUfiP T•IP 3REAI( ISOLAT:ION

.. ' ... . .........

4- . .. . . .......... .. "........... I ... ........ • ............ •. . . . . .............. .. . . . . ...................... .... . . ,........................ ........... 4

* .. " . *. .: . F•ED I aL ED

~~..... I........................................ .......... .......... ........ a

...... ...................................... ...................... .2 8 " k . . . .•. ................... .... ;....... !............ ........ ............ I... ......... ............ ........... .. .......... •............ . . ............ .... ......

.. ......... : ......

........... .............. .. .. ..... .......... .......................... -.... ......... ,......... . . .

a log 289 3o0 ,70 40 see 68 00

- . o . S

* . . . . . • . S • S

- . So . S * o .. S

SS .. . Ti e (a)

a l o ..... - .508 

FIGUR 11 p mrn . S •, iS •

* . . . . S S '

* . . • : :* * . . . • . S

B ." I - u n i i 0

0 106 8000. 3006 400o 5000 6000 "70o0

Time (I) AELAP RELAP

P30001 - P5800 .....

FIGURE II P~.immlrml and kr s~i"nhnieS 1 - nl ralnt31U~iP.---------- - --

v v r
LOFT TEST LP-SB-03, COMPARISON OF RELAP5/'iOD2/CY36.e1 UITIt EXPERIMENT.

I " .r............ f........... ......................... ............ &............ ..................................... ........... ................ :........... "............ ........... .16

............ ..... ........... ....................... .0 .....................

* * • * *

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

..................... to . ......... ........... ............ ................... ..................... ..... ....... ........... ........... ........... ........... ............ ........... .18

, *€ * - ,

, A , . ,, Q ., 

14 ................... .. 1

......... I... ... ..... JED E-P R M 1T

.. . .. . .....

I.............................. . . . . .

* * a0

, ,

I................... ....... 

.. . . .. .................. . . . ............. . ....................... ............ ........... ............. 4 ........................

.. ~~.......r....

* I *

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

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

.......... ...... ............ ............. I- .... t --.t r -' l jr ........... .... I .............. ......... : ............ • ..... ..... . z u• .amu t .- ...• . .... I C l..... ...........

S,..I.. ......

.s ... R I . ....... ........... ........ ........... ............. . ....

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

• • a . , * eTime p u&I

,. • . .0 IE* *L.PIP.flII. F I D*ED 

•.-I, .... .-. -.I• -I..... I , I I: * 6

.I - •' - - . .. I . I * e a• * %. a

P10001 -...... 0.. . . . .

o 1 1 1 .o m* * * . * * a * a * *

* , a e * a * a a a * * , a a a ae** "

a *• 0 * * * • *. ••

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a a. .,

* . .1 :

Tired Ii)

RE LA•P EXPERINEI tilT

PlGIQOi _ PE-PC-OO .....

FIC~iIRF Ia Prinmaril pressure.
LOFT TEST LP-SB-03o COMPARISON OF RELAPS/MOD2/CY36.01 UITH EXPERIMIENT.

z ........................ ! ......... •............ ........... "z ......... ........... ,......... ... '.......... ].......... .......... ................ •....................... .•6

........ ............ ............. 1.......... .......... :........... II...........

' 2

I .. .. . .. ...... as....... ..................... .J................... .....

1 4 * .. .. ... .*

........... ........... • ...... ........... ........ ......... ............ ............ : ............ ............ !........... .....................................

...................... 1....... I .... 

I . t . , . ....... . . .. ...... .

10 . ............ .... ....... .......... t ........... ............ ! ........... ' ............ s ........... ........... T ............. ........... ............ I........... -10

Un O lI IMH )I 2SLTýt RE 2 2fIMH

. I . . 2 . S . S

alp..l. .. I..W M j I . . . . . L PLC[ I . S 1,I ,5. I a,,

1 * **e I I

........................... ............. 4. ....... a s,......... +........... ............ ............ I ........ •................... ..... .................... ,...... ........................ ........... .a

"I I a , , 4

I I 1 9 2

... ....... . 2.. ........... ............ I............ . ............................................................ .......... . ........ ............... . .......... 0

'. ...........

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

e lTime 431

• ,........,....... L.. ... .. +i ~. ....... ; .. ..:f .. - ~i +++

'1 !I I I g * I I

• " . I. ... . a.S-6

P52 .. - PE-SGS-0........

I G I . I .... . .... p" -S"! I I .. ..* .. .. . . . . .. . . . . . .. S ... .. . . .. . S,.. ... . .. . .. . .. .. ... . .. '."" - i

4. . .. S. . .A. . . ........ .......

. I S S • * *•

2*-' * S S

I i S

* 5 a 2___T___a ___

RELAIP IEXPERII¶EIIT

Ps;ees _ PE-SS 0-01.....

FIGURlE 13 5SecondarU pres~llr0.
LOFT TEST LP-SB-(33, COMIPARISON OF RELAPS/110D2/CY36.0i UITH EXPERIMIENT.

e ..j.......i ... ... ........ £..................

~**............

.. ... ....... .... . I It

t .o ..oP .... .......~ . ... I a

a 210 00400E0060

RRflLAT a *EA IOLTRIt (XILRIEIT

RII5 0 20 DEP t6B .....

Tn

F IGURE 14 [~ i Br a ItnP donaltU . ~QATl94

908

.600

-7800

GO0

Sao

I,%)
LOFT TEST LP-SB-e3, COMPARISOH OF RELAPS/lOD2/CY36.01 UITH EXPERIMIENT.

.ge ............ ...................... .......................... . . . . . .g~ * . . . (EXP ER IM ENT" .. ..... . .g a

IREAK ISOLATIQN (RELAp . : redo L BLU DIn RELAP

Be*- . .. ... I ...... .......... .............. ...... ...... .. ........ ............ ................................ ... a

706- ...... ......' ........................ ' ............ . . . . . .. . ....... ........ ... ' ......... .............. ' .. .. ..... ' .. .... .... ..........

.t ........... i N..- .. . ...................... .. ... ........................ ........................ ...... ......... ... .. .. ..... .... .... ...

........ U? TPIP (EXPtRIIIEITl

~see j ....... tRIP tREJAP..P *

468 I II 6 ........... : . . . ... .......... ......... .......... ................. .... .... ..........

4i ........ .....1 " l ..... .' .' l ... . .......... .. . .... .... ......... .. .. ..... ...... ... -6

3 0 0 ........... ...... .. ........ U. ...... R .I .........I. . ........... ..... .. ..... ......... .... n.. .. ... ... . -3 0 *

- 08. o ........ •.... •............:"... . ....... , ........... ... ........ • ............... ........... .... ....... ..... ! .... . :Y - o

8 300.

00 ...... DE-PC-1..... ....-. 0 .. . , . t .,. • ,..oU

1*.J' , I .)].. E . , T. . • . . l

o , • . , ,T. •)

REL? XPE-IEN

HI00........I ...... ...... PC. 1.......8... .5 .... - ..... ...... .... ... ... I. ... ... ......- 0

FIGURE 15 Cold l° denaiti
LOFT TEST LP-SB-03, COMPARISON OF RELAPS/MOD2/CY36.01 UITH EXPERIMENT.

go ..... .......... ............... ...................... .-...... - ............... :- a

DREAKIOAlI EX~KnrT IRCAK :ISOLATIQN (RELAP)

FEuD LI LE D (REL

see- ........ I ............ ... . ........ .: ........... ............ , ........... , ........... 4 ........ '. ........... nsee .--. . R'FED I (EXP RIIKT

I piiUMP TeIP (EXPFRI IEt1T. I.2

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

!P. .. . - 0

14 2 * .

~.. .......... .............. . . ........

2 0 .... .. ...... .. • ............. I.. . ... . . ... ........ ...... . ............. ... ......... .. ............. ..... *1 .......... 68

d I 2I :: '

IiI. . 2 , : 

I"i. I ."

lee.... ..... . .. ........ . .. ........... ?............! .... ........ ... ' .... ....... .. o

30......... S ...... ..... . . . .t

120 200 400638604 200 

a. 2 , .- .. :*. . .e-

- 1 1 - D I 

2IGUR :6 Hot l .... 2I U

S I ' I

* , .. 2. S i i . * . . ae ........ . , ....... i-t ..... ... ....... 4......4 .°°°%°

10.............I" ............................... )........... I........... I................... iI...... I.......................

\. . ,l i . •...._'

I. :I , .. I' . -. , ___

T.. a

RELA.......P.......-E....... P.....R...I-iI.. T ....... Rit.......IO ........I .... -as............ .......---- '-•"--

F1O! '1" Hot lo ' it:t, ' 
LOFT TEST LP-SB-03, COMPARISON OF RELAPS/MOD2/CY36.01 UITH EXPERIMENT.

PUHlP .1RIP (RqiLAP) I ....... ..... 1 . J i. pi v

5.'

ES'

S

'I

.5

a, A. I .I

I i

t . ........ o ................

S51.TO5. . . ..........

ISOL A.1011 ( EXRERltlEW:T)

.. -1 .. .......... I ..... I....... .. ........

IL.i1 L DtILLD E4EXkftIfHl

FE4D L BLELD ,REI.,#•,

o . o~' *°. ° . .. . . . ,. . .0 S . ° o~ ° ................ 5 ..............

......... o..............a..... . .

3ock t ...........

~5*1

t

200-I ........... ................. °...........d

•.... ....... i

,-3 0%

200O

Tima (s)

RELAP EXPERIM~IT

M1011002 - DE-PC-eeB.....

FIGURE 17 FIGURE 1?Loop seat downside~ density.
I 8~

I'

-t

0

II

7'

6

?0

LOFT TEST LP-SB-03, COMPARISON OF REIAP5/MOD2/CY36.01 UITII EXPERIMENT.

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

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

BREAK IOLATIT1 (RELMUM)

FEED BLEED (RELAPI .• ....................... !....................... !.......... ............ !... .......... ..... . • L: • " i; (• i., ... ............. .........................

ACCUI 0Hn (EXPEII1EHTi

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

18 . ... I................ ...... . . . . . ......

00., ....................... I ....................... .......... ............ ... .......... .... ... ...................... ,....................... ........................

....................... !....................... !.......................1 ... .......... .... .... ...................... ....................... ........................

* 2

.o ........................ ....................... !.......................i ....................... . .................. ........................ .........................

*Ti

' 2

I a

TEMP280011 - ....... 6 .. ........ i..... 18 t.......................'"........" .... a.........."...........a I 2.............................

i I I 3508 4008 4See500550&0 6O O

Ta.

RELAP EX(PERIrIEtlT

TEI¶P23e8011 -e _ T1-5l86-ODS5.....

FiGUlRE 1a Clad tamperaLureD 0.14. "Level.

-000

-300

00

a Is)
.1fP

LOFT TEST LP-SB-03, COMPARISOH OF RELAPS-'MODa/CY36.1 UITH EXPERIfMENT.

1880 ....... ........................... li.I...................... ....................

........... UREAK.JjflT.wL1L EXRJIEll T.) ......... *bREAK ISOLA~TW11I IRELAP)

FEED B DLEED (RAELAP): g e .. a . ... .. E . !: . .E .. p ........ ., ! . . . . ..... 

9 . .................. ...... ! . ................ I..... ..... .... !. ... ................. I,........... o, , .E, >. ....... ............ 6 a

i J A~~CCIll ONl IRExP~tlllt

oo..................... ... .. .......... .....

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

A I

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

s ee - ......... . ............. .. ... ... . ....... ............... ........... ........... ....................

I / , /

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

Geo ............ ... .............. ............... •.... .....................

• . I /-.. I O ......... 

I l r i **

3500 4008 4500 5000 55300 G~OO) 6500 70'

RELAP EXPERIIIEIITTi

TEMP23000210 - TE-41113-015 ..

F1CURE 19 Cad temperature, 0-42u level.

Ko

-0400

-600

a 10
LOFT TEST LP-SB-03o COMPARISONl OF RELAPS/MOD2/CY36.0I UITH EXPERIMENT.

1060-

I'

I

a

S.-I

800

700-

....................... i

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

I........... ..............

...... 

. ......... 

.............. oo°°°o . ........ ...... •.o° ................. o................... ..........

* S

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

o.. ................

...

* I

S.......... EJg. 5

....... oo. ............ I

oo....oo.... ...........

.~1 o . ...o .. . . . . 7 . ..oo ....° !

II

o° ° o ° ° .... " "...

Io

...... .I........ 

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

li~n.Jnh..E.............. °oooo° ° . ............ o.oo.oo .°.°°.o.°o oo .. . . ° ° ~ o.o . . .... °....°. °.. I I

BREAK ISOLAiTI! (RELAPI

FEED 11 BLEED (RELAP):

e

.. ...... ..Ffj DL BLEED. .E...R....... I iCC 6itOil7R'ELAP3

I I

I I

! o

ACCU1R Oil(EXERI.HT

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NPAC FORM 2326 UIL WiCLIAR 049GULAYO04Y COAMIIIO4N I m1PORT NUvmiER 1A.4..ev IioC.. W I VaE . *efti

(2641 i4ACM 1102.r

3201.3202 BIBLIOGRAPHIC DATA SHEET NUREG/IA-0013

SEE INSTRUCTIONSOf T-E REVERIA GD/PE-N/535

2 TITLE ANO SUII TITLE J LEAVE ,LANK

RELAP5/MOD2 Calculation of OECD-LOFT Test LP-SB-03

4 OATE REPORT COMPLETED

MONTH I YEAR

, Au*NR,,, May 1987

C. Harwood, G. Brown , 4DATiERERTIUAO January 1 1990

7 PERFORMING ORGANIZATION NAME AN° MAILING AOORESS JIkN*ZV ChJ/ B, PR CTTA-TRNWORAK UNIT NUMBER

Central Electricity Generating Board

Barnett Way, Barnwood I FINORGRANTNUMER

Gloucester, GL4 7RS

UNITED KINGDOM

SO. SPONSORING ORGANIZATION NAME ANO MAILING AOORIESS (In¢eftleA. C44 1la. TYPt OF REPORT

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission Technical Report

W a s h i n g t o n , D C 2 0 5 5 5 . PERiOOCOV E RO ,,-1 ..a -a

12 SUPPLEMENTARY NOTES

13. ASISTRqAT 170-1 WA

This report compares the results of the

experimental measurements.

RELAP5/MOD2 analysis with

A simulation of test LP-SB-03 was previously carried out at GDCD using the

RELAP5/MOD1 code. RELAP5/MOD2 was developed from RELAP5/MOD1 and contains

more sophisticated hydraulic models and constitutive relationships.

Comparison of the RELAP5/MOD2 and MOD1 calculations show that RELAP5/MOD2

performs better than RELAP5/MOD1 in a number of key areas; notably mass

errors are much reduced, there is improved numerical stability, and

improved separator modelling and modelling of accumulator injection.

I4 OOCLMINT ANALYfSIS 4 REYWOROSOASCRIPTORS IS AVAI,.AiLAiTY

RELAP5/MOD2, ICAP Program, Small Break, LOFT STATEMENT

Unlimited

SECURITY II CLASSIOICATION

6 JOE NTIFII .RASIOIN.EO TERMS G c"Tassi fied

r'crassified

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PENALTY FOR PRIVATE USE, $300

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U USNRC j

PERMI No. G-67

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