NUREG/IA-0096

- -AEA-TRS-1050

International AEEW-R2501

Agreement Report

Numerics and Implementation

of the UK Horizontal Stratification

Entrainment Off-Take Model

Into RELAP5/MOD3

Prepared by

W. M. Bryce

Physics and Thermal Hydraulics Division

AEA Thermal Reactor Services

Winfrith Technology Centre

Dorchester, Dorset

DT2 8DH, United Kingdom

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

Washington, DC 20555

June 1993

Prepared as part of

The Agreement on Research Participation and Technical Exchange

under the International Thermal-Hydraulic Code Assessment

and Application Program (ICAP)

Published by

U.S. Nuclear Regulatory Commission
NOTICE

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and

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NUREG/IA-0096

AEA-TRS-1050 @International AEEW-R2501

Agreement Report

Numerics and Implementation

of the UK Horizontal Stratification

Entrainment Off-Take Model

Into RELAP5/MOD3

Prepared by

W. M. Bryce

Physics and Thermal Hydraulics Division

AEA Thermal Reactor Services

Winfrith Technology Centre

Dorchester, Dorset

DT2 8DH, United Kingdom

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

Washington, DC 20555

June 1993

Prepared as part of

The Agreement on Research Participation and Technical Exchange

under the International Thermal-Ilydraulic 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 IKingdom (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 partywould not infringe privately owned rights.
Numerics and Implementation of the

UK Horizontal Stratification Entrainment

Off-take Model

Into RELAP5/MOD3

W M Bryce

SUMMARY

RELAP5/MOD3 is a computer code for the the analysis of fault transients in light water reactor

systems. It has been subject to an international development exercise.

Among the fault transients which can be analysed using RELAP5/MOD3 is a loss-of-coolant

accident (LOCA) in a Pressurised Water Reactor (PWR), in which a small break occurs in

one of the large diameter horizontal pipes forming the reactor inlet or outlet legs. In this

situation the steam and water in the pipe may separate to form a liquid level. The quality of

fluid discharged from the break (proportion of the mass flow which is steam) then depends on

whether the break is above or below the liquid level. RELAP5/MOD3 contains a special model

to calculate discharge from an off-take connected to a large diameter horizontal pipe in which

there is stratified flow, referred to as the horizontal stratification entrainment (HSE) model.

Apart from small break LOCAs, such a model is also needed for analysing other abnormal

conditions in PWRs.

Early in its development, the RELAP5/MOD3 HSE model was the same as that of the

RELAP5/MOD2 code. This was assessed by Ardron and Bryce [1] who found that the model

tended to under-predict significantly the discharge quality in many cases. They selected

improved correlations for the off-take quality and implemented them in a modified version of

RELAP5/MOD2 Cycle 36.04. The modified code was shown to give much improved agreement

with separate effects test data.

This report describes the numerics and implementation details for the modification of

RELAP5/MOD3 to use the same improved correlations. These details include the areas where

the use of the HSE correlation set are extended outside of its range. The modifications, which

were incorporated into pre-release code version 411, have been retained in the first "frozen"

release of the code (version 5m5). Areas where changes have been made by EG&G in producing the release version which might affect the modelling are noted in the section on programming details. Particularly noteworthy is the restriction which apparently excludes the full

control of the HSE model at the internal junctions of PIPE components.

A simple test problem is used to verify the RELAP5/MOD3 coding of the correlations, making

use of the control system logic. This problem, run using the release code version, also

AEA-TRS-1050 - iii -
demonstrates that this version seems to be more prone to instability than the pre-release version 411. The problem is not believed to be associated with the HSE model.

Physics and Thermal Hydraulics Division

Winfrith Technology Centre

March 1991

AEA-TRS-1050 - iv -
Contents

1. INTRODUCTION ............................................................................................................................................ 1

2. OFF-TAKE DISCHARGE QUALITY CORRELATION SET ................................................. 2

2.1. Critical Depth for Entrainment ....................................................................................................... 2

2.2. Discharge Flow Quality ...................................................................................................................... 2

2.2.1. Vertical Upward Branch ......................................................................................................... 2

2.2.2. Vertical Downward Branch .................................................................................................... 2

2.2.3. Horizontal Side Branch ............................................................................................................ 3

3. EXTENSIONS OF THE CORRELATIONS ...................................................................................... 4

3.1. High Flow-rate Limit ........................................................................................................................... 4

3.2. Extreme Voids ......................................................................................................................................... 4

3.3. Allowing for Slip at the Take-off Junction ............................................................................... 5

3.4. Allowing for Counter-Current Flow at the Off-Take Junction ................. 5

3.5. Treatment of Side Off-Take of Non-Negligible Area ................... ; ..................................... 6

3.6. Treatment of Top and Bottom Off-Take of Non-Negligible Area ............... 7

3.7. Treatmentof Large Critical Depths .............................................................................................. 8

4. NUM ERICS OF THE IM PLEM ENTATION .................................................................................... 9

4.1. Time Level of Properties ................................................................................................................... 9

4.2. Condition the Correlations ................................................................................................................ 9

4.3. Improve Numerical Stability for Unchoked Flow ................................................................. 10

4.4. Improve Numerical Stability for Choked Flow ...................................................................... 11

4.4.1. Liquid Entrainment .................................................................................................................... 12

4.4.2. Gas Pullthrough ........................................................................................................................... 13

5. PROGRAM M ING DETAILS .................................................................................................................... 15

5.1. New Variables ......................................................................................................................................... 15

5.2. Inpui Routines ......................................................................................................................................... 15

5.3. Output Routines ...................................................................................................................................... 15

5.4. Initialisation Routines .......................................................................................................................... 16

5.5. Transient Routines ................................................................................................................................. 16

6. PROGRAM TESTING ................................................ 19

7. CONCLUSION .................................................................................................................................................. 21

A. Test Data Listing .............................................................................................................................................. 29

AEA-TRS-1050 - v -
List of Figures

Figure 1 Test Entrallc - Up Case Flow Quality ..................................................................................... 23

Figure 2 Test Entrallc - Up Case Flow Quality ..................................................................................... 24

Figure 3 Test Entrallc - Side Case Flow Quality ................................................................................... 25

Figure 4 Test Entrallc - Side Case Flow Quality ................................................................................... 26

Figure 5 Test Entrallc - Down Case Flow Quality .............................................................................. 27

Figure 6 Test Entrallc - Down Case Flow Quality .............................................................................. 28

AEA-TRS-1050 - vi -
Notation

A area (m 2 )

C constant in Equation (5)

d diameter of off-take pipe (m)

D diameter of main pipe (m)

g acceleration due to gravity (m/s2)

G mass flux (kg/m2/s)

h "height" of liquid level in main pipe with respect to centre of the

off-take pipe entrance (m)

For a top off-take this is the distance of the liquid level from the top

of the pipe cross-section

For a side off-take this is the distance of the liquid level above the

off-take centre, it is negative if the liquid level is below the centre

For a bottom off-take this is the distance of the liquid level above the

bottom of the pipe cross-section

hb critical value of h at which entrainment or pull-through

commences (m)

K empirical constant in Equation (1)

p pressure (MPa)

R non-dimensional height (= h/hb)

S slip ratio (= vs /vf)

S* modified slip ratio

v velocity (m/s)

w width of stratified liquid surface in pipe (m)

W mass flow-rate (kg/s)

x quality (= WL /W)

R static quality (= ocp 5 /p)

xo reference quality defined after Equation (4)

at volumetric concentration or area fraction

t angle used in Equation (12)

p density (kg/m3)

Ap density difference (= pf - pg)

AEA-TRS-1050 - Vii -
Subscripts

c associated with choked flow

f property of liquid phase

g property of gas phase

j property of junction between main pipe and off-take pipe

k property of continuous phase

K property of donor volume

Superscripts

n an old timestep value

P an intermediate value

(1) an intermediate value

* an intermediate or modified value

AEA-TRS- 1050 - Viii -
1. INTRODUCTION

When a gas-liquid mixture discharges from a large diameter horizontal pipe into a small diameter off-take branch, the discharge flow quality depends on the liquid level in the main pipe.

If the entrance to the off-take branch is submerged, the discharge flow is mainly liquid which

may contain an entrained gas component. If the entrance is above the liquid level, the

discharge is predominantly gas, which may contain an entrained liquid component.

The necessity for modelling this situation has been discussed previously [1]. Also, the

RELAP5/MOD2 model to compute the quality discharged into a small off-take pipe when there

is stratified flow in the main pipe (so called 'horizontal stratification entrainment (HSE)

model') was assessed. The model was found to have a tendency to under-predict significantly

the discharge quality over a wide range of conditions. An alternative set of discharge quality

correlations were included in a modified version of RELAP5/MOD2 and shown to give considerably improved agreement with separate effects data.

This Report presents the numerics and implementation details to add the same improved

discharge quality correlations into RELAP5/MOD3. In the light of experience with the modified

RELAP5/MOD2 code, some of the numerics has been slightly changed for RELAP5/MOD3. The

description is quite detailed in order to facilitate change by some futtire code developer. A

simple test calculation was performed to confirm the coding of the correlations implemented

in RELAP5/MOD3.

AEA-TRS-1050 -1I-
2. OFF-TAKE DISCHARGE QUALITY CORRELATION SET

To aid clarity, the correlation set used is repeated below. The reasons for its choice and the

references to the originators are given in [1]. First there are correlations for the critical depth

for entrainment and then correlations for the off-take discharge quality.

2.1. Critical Depth for Entrainment

The critical liquid height or depth hb is a function of the off-take conditions. Its correlation has the same form for all orientations:

hb = KWk°'4/(gpkAp) 0 2 (1)

where k refers to the 'continuous' phase, which is the gas phase for an upward branch,

the liquid phase for a downward branch. For a horizontal side-branch, k is the gas phase

when the liquid level is below the nozzle centre, and the gas phase otherwise. The values

of K chosen are:

VERTICAL UPWARD BRANCH

VERTICAL DOWNWARD BRANCH

HORIZONTAL SIDE BRANCH

K = 1.67

K = 1.50

K = 0.75: gas entrainment

K = 0.69: liquid entrainment

(2)

2.2. Discharge Flow Quality

The correlations for discharge quality are given below according to off-take orientation. In

these expressions R is the non-dimensional height of liquid level in the main pipe with

respect to the centre of the off-take pipe entrance and is defined in the Notation:

2.2.1. Vertical Upward Branch

x = R3.25(1-R)2 (3)

2.2.2. Vertical Downward Branch

X = Xo2"SR[ 1-0.5 R(I+R)xo('-R) ] 0.5

(4)

AEA-TRS-1050 -2-
where

Xo = 1.15/(1+q4b7-)

2.2.3. Horizontal Side Branch

x = XO(I+CR) [1-0.5 R(I+R)x(1-R)] 0.5

where

xo= 1.15/(I+Nrf /P,)

and

f 1.09 for gas entrainment

C = 1.00 for liquid entrainment

For this case R is negative if the liquid level is below the main pipe centre.

AEA-TRS-1050 -3-
3. EXTENSIONS OF THE CORRELATIONS

The correlations for off-take discharge quality are based on simple experimental situations

whereas RELAP5 is a general purpose code and may have flow conditions different to the experiments. For example the main pipe flow may not be low or the off-take may have

counter-current flow. All such aspects have to be allowed for in the implementation and are

considered below.

3.1. High Flow-rate Limit

In the current RELAP5/MOD3 HSE model, homogeneous discharge conditions (that is normal donoring) are assumed in flow regimes other than stratified flow. This assumption

fails to recognise that partial separation of the phases occurs in the slug, plug and annular

flow regimes, in horizontal flow. As stated in [Ij, this is allowed for by applying the

HSE model to all horizontal flow regimes except dispersed flow, which is assumed to be

entered when G > 3000 kg m- 2s-1. A linear interpolation zone is defined between

G = 2500 kg m- 2s-1 and G = 3000 kg m-2s- 1 in which the void fraction transitions from

the value calculated from the quality given by the HSE correlations, to the donored value.

The expression used for the mass flux G in this case is given below:

G = Max[ ICgKPBKI VgKI + afKPfKI vfK, j /AK (6)

This choice should suppress the HSE off-take model if there is high flow anywhere in the

upstream volume.

3.2. Extreme Voids

The interpolation factor introduced in the previous section is reduced towards zero (such

that the donor value for the off-take conditions is used) linearly if either of the phase area

fractions (gas and liquid) of the donor volume approach zero. The boundaries of the two

transition regions are

a•K = 10-5

and (7)

otf = Max[1 2*10-7 , Max[1 2*10-4, 2*103'PgK/PfK]

In the above equation, the subscript K denotes the upstream volume according to the

phase flowing from the horizontal volume. These particular void limits are based on

those used in the code flow regime package. These limits imply, for example, that if the

donor volume gas fraction aSK has the value 5*10-6 then the interpolation factor is

halved.

AEA-TRS-1050 -4-
3.3. Allowing for Slip at the Take-off Junction

The correlations given above specify the flow quality in the off-take branch. RELAP5 requires the void fraction of the flow in the off-take. A desired flow quality can be obtained indirectly by converting the quality to a void fraction using a modified slip ratio as

below:

S Max 1.0, Min Max[ Pfj /pj ,10-7] 0., i.5Vi (8)

The modifications in this expression restrict the range of slip ratio and use absolute velocities to maintain a finite positive result even when the flow becomes counter-current (this

state is discussed further below) and to avoid discontinuities. The limits are arbitrary but

are expected to be reasonable in most situations. In most cases S*. will be the actual

junction flow slip ratio. (The release version 5m5 of RELAP5/MOD3 now has a junction

flow quality defined but this extension has not been altered).

3.4. Allowing for Counter-Current Flow at the Off-Take Junction

For co-current off-take flow either (x, or oaf is calculated from the correlations as

described above and manipulated into a junction value agj or ar,. The other phase junction area fraction is obtained by requiring that the phase area fractions sum to unity.

For counter-current off-take flow the correlations are definitely outside their range of validity. However the code can enter this state. It was decided to use an ad hoc extension of

the HSE model with the objective of minimising discontinuities in phase flow rates when

the other phase off-take flow reverses. The junction phase area fractions calculated by

RELAP5 in the absence of an HSE model do not normally sum to unity for counter-current

off-take flow. Thus Summing to unity was not taken as an objective. The ad hoc extension model is outlined below.

In this HSE extension model for counter-current flow, the gas area fraction is calculated

on the basis of gas upwind conditions and the liquid area fraction is based on liquid

upwind conditions, in line with the normal code practice. If the upwind volume for a

phase is horizontal then the HSE correlations will be used for that phase. However four

abnormal states may arise due to the flow being counter-current:

(a) A gas flow from above the liquid level which could entrain liquid except that the

liquid flows the opposite way.

(b) A liquid flow from below the liquid level which could pullthrough gas except that the

gas flows the opposite way.

(c) A gas flow from below the liquid level which would normally be pulled through by a

liquid flow except that the liquid flows the opposite way.

AEA-TRS-1050 -5-
(d) A liquid flow from above the liquid level which would normally be entrained by a gas

flow except that the gas flows the opposite way.

For case (a)/(b) the reverse flow is ignored (the flowrate of the non-continuous phase does

not appear in the correlations) and the gas/liquid area fraction calculated from the correlations. Cases (c) and (d) would not be expected to occur frequently. A fixup is required

that will not introduce large discontinuities at phase flow reversals or when the level

crosses a side off-take. For case (c)/(d) the gas/liquid area fraction is calculated from the

correlations as if the liquid/gas flowrate was outwards but at the limit of zero. Thus there

should be no discontinuity at phase flow reversals. For side off-take, at a void fraction of

0.5 in the horizontal volume Equation (5) gives a quality that is independent of flowrates

so there is no discontinuity as the level passes the off-take for counter-current flow.

The RELAP5/MOD2 model has a partial implementation of this procedure. It fails to deal

with two cases both involving two horizontally stratified volumes connected by a small

orifice with counter-current flow. The two cases are where the orifice junction has been

marked as an upward oriented off-take junction or a downward junction. In the first case

the liquid is just given a donor calculated area fraction. Similarly in the second case the

gas is given a donor value.

3.5. Treatment of Side Off-Take of Non-Negligible Area

The horizontal stratification entrainment model in RELAP5/MOD2 contains coding for

treating the case where the liquid level in the main pipe is between the elevations of the

top and bottom of the side branch entrance. The procedure used ensures that the junction

void fraction tends to the void fraction in the main pipe when the side branch area tends

to the area of the main pipe. Essentially there is an interpolation between the HSE model

value and the donor value of void fraction. Virtually the same procedure is used in the

implementation of the HSE model of [I] into RELAP5/MOD3.

To illustrate the procedure, consider the case where the liquid level is above the centre of

the off-take branch (cigK <0.5). Let (x% be the void fraction at which the liquid level

would be at the elevation of the top of the side branch and let oCF be the void fraction

calculated from the pull-through correlation. Then the liquid area fraction resulting from

the procedure is calculated from the equations

X•f 1=C"•Cg *g a : {gK

(9)

C.f a4{ I:-} _c,+{ I agK] <asK

where a5SK is the void fraction in the (gas) donor volume.

AEA-TRS-1050 -6-
In fact, there is one additional complication. In the HSE model coding of RELAP5/MOD2

the void fraction is modified. Within the context of this new model, before c*4 is used in

Equation (9) it would be modified as follows:

a * .-. Min ,0.49 * 0.85 (10)

Documentation of the reason for this modification has not been seen by this author. It appears to extend the range of gas void fractions within which interpolation of the HSE and

donor models may take place to a range of at least 0.4165 to 0.5835. It has been partially

implemented in this new model with the factor 0.85 being omitted in Equation (10).

An analogous equation to (9) is used for CgK >0.5 (entrainment). For the purposes of

these calculations, the off-take orifice is assumed to have the diameter dcK given below:

dcK := DK 4/j /AK (U1)

In this implementation another modification is made. The critical depth hb is given a

minimum value of half of the estimated off-take diameter dCK. This helps avoid rapid

changes as the level crosses the off-take for low off-take flow.

3.6. Treatment of Top and Bottom Off-Take of Non-Negligible Area

In the RELAP5/MOD2 coding, a procedure based on Equation (9) is also used for top and

bottom off-takes. As noted in [I], this seems unreasonable since the liquid does not intersect the off-take entrance for these cases. However, some form of smoothing may be

necessary when the liquid level approaches the level of the off-take. The correlations

have not been demonstrated to be valid with large off-take area but the the implementation described here gives code users the option of using them or not.

The smoothing used is based on a physical picture (see the next page). Looking at the

main pipe through the off-take, if the liquid level is near the off-take and the edges of the

liquid are in the field of view then the smoothing is applied. The smoothing is by interpolating to the donor void value according to the area of the field of view not occupied by

liquid for a bottom off-take and according to that occupied by the liquid for a top offtake. The algorithm used is illustrated by the example of a bottom take-off:

= 1-ocF ŽCSK >0.5 or siný >1

(12)

if = 1-i2 sin, cos +,] otherwise

AEA-TRS-1050 -7-
where

siný = w Min[ DKdCqK

and w is the width of the liquid surface. This algorithm is slightly changed from that used

in the RELAPS/MOD2 code version mentioned in Reference [1].

Liquid edge

Schematic of View of Liquid Edge Through Top Off-take

3.7. Treatment of Large Critical Depths

It is conceivable that the critical entrainment depth hb could imply a depth which is not

contained within the main pipe. In this case the correlations (1)-(5) would predict gas

pullthrough when the main pipe contains only liquid, or liquid entrairunent when the pipe

contains only gas. Such extreme values of hb must take the correlations outside their

range of validity. In this RELAP5JMOD3 model therefore it is assumed that the range of hb

is limited to the span of the main pipe diameter. This will imply less entrainment when

the limit is in effect. This algorithm is different to that used in the RELAPS/MOD2 code

version mentioned in Reference [1].

AEA-TRS-1050 -8 -
4. NUMERICS OF THE IMPLEMENTATION

A straightforward implementation of the correlations and extensions described above using old

timestep values for all required properties is a recipe for disaster. Instead several improvements on this approach are used. These are described in the following Sections.

4.1. Time Level of Properties

The current values of almost all the property variables are used. (Current means the

values at the time the HSE subroutine HZFLOW is called). The exceptions are the junction phase area fractions oxfj and ocj used to evaluate the continuous phase flowrate Wk of

Equation (1). For these the old timestep values a 1jn and orn are used for two reasons.

Firstly, the old timestep values will have been calculated with the HSE model (unless

there has been a velocity reversal) and will be a better starting point than donor values

from any intermediate calculation. Secondly, there is no change in values with this choice

if a timestep is rejected and the calculation retried with half the timestep.

There is a special case however. If the flowrate Wk calculated from the old timestep

junction phase area fraction would result in no entrainment then the flowrate Wk is recalculated using assuming the continuous phase area fraction oj was 1.0 corresponding to

no entrainment. This helps to avoid large perturbations as entrainment starts and stops.

4.2. Condition the Correlations

Equations (4) and (5) for flow quality contain terms of the form

[1--0.5 R(1+R)xo(1-R)] 0.5

This term changes rapidly in the region of R = 1. To avoid numerical instabilities due to

this behaviour the correlations are conditioned by replacing the tenn by a linear variation

between its values at R = 0.9 and R = 1.0.

The non-dimensional height (or depth) R involves a division by hb. To avoid problems

when hb-40 at zero off-take continuous phase flow Wk it is given a minimum magnitude

of 10-6 m. The value of Wk is altered to the value Wk(l) which maintains the relationship

Equation (1). (Such an alteration is also done if the minimum magnitude of hb given for

side off-takes, described just after Equation (11), is used).

To avoid other singularities, the density difference Ap is given a minimum value of

10-7 kg/m3.

AEA-TRS-1050 -9-
4.3. Improve Numerical Stability for Unchoked Flow

The explicit formulation described above is an invitation to instability. To try to overcome this a special procedure is applied. This is illustrated below for the calculation of

liquid entrainment in co-current unchoked flow. Basically the procedure uses linear approximations of the non-linear functions. The resulting linear system is solved to give a

better, more stable, calculation of the junction phase area fractions.

The entrainment is caused by the steam flow Wg (Wk is W, in this case) from which a

critical height hb is calculated using Equation (1). This height may be modified if it is

small as described above in which case it is associated with a modified gas flow W,(1).

Without the modification, W,(1 ) is equal to W8.

The appropriate entrainment correlation gives a flow quality which is converted into an

off-take junction gas area fraction using the slip ratio S * defined in Equation (8). Again

this may be modified, by the finite area off-take modification or the high flow-rate

modification for example, to give a gas area fraction which is denoted using the superscript P. This gas area fraction otj" is unlikely to be the same value as that (otj3') used to

calculate W. and this is the source of instability. The gas flow W. may be considered as

a function of the initial gas area fraction c,,n and the gas area fraction aaip may be considered as a function of the gas flow. Then working to first order accuracy, the junction

gas area fraction oj is set to the value which gives a gas flow which produces an entrainment giving rise to a self consistent gas area fraction.

This definition is represented by the following equations:

ct~i = o+ -[ 1 Wg" (W1)](3

s W5 (13

WccW+ DWSi [ a* ---. "' (14)

W9* = W9+ Dn 'j(4

where in this case

L_ = Av p (15)

and Dctir / DW. is non-positive. This partial derivative is evaluated assuming the slip ratio S*i and the degree of mixing of pure donor derived ac are constant. The intermediate

gas flow W,* is eliminated leaving the following expression for ag.

o. +-ac-g awP Ws -W8(,) -aX" Iawn

0i-O~g i aw 9~ aw agip Dn(16)

1 16

9k~~

D0Si nD

AEA-TRS-1050 - 10-
Under some circumstances the partial derivative -5-- is explicitly set zero: OWg

i. If the large critical depth modification was invoked.

ii. If the flow was in counter-current cases (c) or (d).

iii. If agtJP is 1.0 and oam" is 1.0. (If Ocgj" is not 1.0 and the modified correlations give a

non-zero derivative this is used to reduce perturbations as entrainment stops and

starts.)

iv. If agip is 0.0.

If the process is not calculated to be a negative feedback process, then the gas junction

area fraction agi is left at the value a .

Exactly the same form of procedure can be followed for counter-current flow for each

phase flowing from a horizontal volume. For gas pullthrough the roles of gas and liquid

are exchanged and the junction liquid area fraction is calculated by an expression like

Equation (16):

4-fjP r nWf

af=p

8cxf1" •Wf

Again under some circumstances the partial derivative jis explicitly set zero: W•f

i. If the large critical depth modification was invoked.

ii. If the flow was in counter-current cases (c) or (d).

iii. If afjp is 1.0 and cfj" is 1.0. (If af.n is not 1.0 and the modified correlations give a

non-zero derivative this is used to reduce perturbations as entrainment stops and

starts.)

iv. If OxfjP is 0.0 and afjn is 0.0. (If oai is not 0.0 and the modified correlations give a

non-zero derivative this is used to reduce perturbations as liquid first appears.)

4.4. Improve Numerical Stability for Choked Flow

When the off-take flow is choked and co-current the assumption that only the dependence

of the gas flow on the gas area fraction (Equation (14)) need be accounted for to obtain

stability has been seen in practice to break down for liquid entrainment. Gas pullthrough

with choked flow has also been seen to have problems. Procedures to improve stability

for these two cases are described in the following two Subsections.

AEA-TRS- 1050 - 11 -
4.4.1. Liquid Entrainment

As stated above, the stability obtained by using the assumption of Equation (14) is not

always satisfactory. Account has to be taken of the change in choked flow gas velocity Vg associated with a change in junction void fraction a&. Over a wide range of

void fractions, an increase in junction gas area fraction results in an increase of

choked gas velocity. This then would cause more entrainment of liquid in the next

timestep reducing the junction gas area fraction. This is a negative feedback process

which can cause oscillations.

The approximation used to take account of the change in choked flow gas velocity is

to assume that vcpj is a constant Gc and that the slip ratio S is also constant where

vc = MY.Pfjvg +(1-ctj )Pgvf (18)

C jpfj +(l-axj )Pgj

and

Pi = agipgj +(1-cLs )Pfj (19)

Velocity vc is used in the code's choked flow model. The assumed constant product

GC is evaluated with the old gas area fraction ocin and current velocities. The assumptions then imply a relationship between vF and ct%, and hence between WL and

oti. This latter relationship is linearised about oCL n and used to replace Equation (14).

The derivative is constrained to be non-negative. The equations involved are Equations (20)-(25) below.

vc = n(20) Iag"Pgj +Clj"P0J

V vc(cgjnpfj +C--fjnpj )S (21)

v CgjnpfjS+aofjnpg(

WS = Avgpao•s" (22)

where, because choked flow will be co-current, when calculating derivatives it is assumed that

Jn= l-A' (23)

AEA-TRS-1050 -12-
The replacements for Equations (14) and (16) are

W = Wg+ Wg [ agj-ogn - (24)

and

1XgA = W5 W(_a gin ]j (25)

1g

where W9 and DW !/ Docjn are evaluated from Equations (20), (21) and (22).

4.4.2. Gas Pullthrough

The situation is different for gas pullthrough. The negative feedback process

described for liquid entrainment becomes a positive feedback. An increase in junction

liquid area fraction results, for a wide range of void fractions, in a decrease in junction choked flow liquid velocity. The next timestep would then have less gas

pullthrough (ignoring the countering effect of the increased liquid area fraction on the

liquid mass flowrate) and hence there would be an increase in junction liquid area

fraction. This may or may not give rise to instability. Using a procedure like that

described above for liquid entrainment is likely to exacerbate any potential positive

feedback instability because it could result in a reduced or negative denominator in

the replacement expression for Equation (16) due to a small or negative value of

DWf /Dfjp. This potential problem was not realised when the RELAP5/MOD2 code

version of Reference [1] was developed.

Another problem observed in the RELAPS/MOD2 code version of Reference [1] is associated with the choked flow model transition between the subcooled and two-phase regimes. It is illustrated by considering a horizontal volume containing stratified gas

and liquid with the liquid being subcooled. Consider a side off-take below the liquid

level with the choked outflow liquid causing gas pullthrough. As the liquid level falls

the equilibrium quality of the flow from a side off-take can change from subcooled to

two-phase (the actual quality being two-phase throughout). As this happens the

choked flowrate drops. This causes a drop in pullthrough resulting in a drop in offtake equilibrium quality to a subcooled value. If the choked flow routine is correctly

coded (that is it uses junction equilibrium quality rather than upstream volume equilibrium quality) the next timestep will use the subcooled choked flow model giving an

increase in off-take flow. This cycle can continue causing oscillations with period

linked to the timestep size. This potential problem was not realised when the

RELAPS/MOD2 code version of Reference [1] was developed. At the time of this

development, it was expected that the released version of RELAP5/MOD3 would be

based on the junction static quality and that this might also suffer from a similar instability.

AEA-TRS- 1050 - 13 -
In order to reduce such oscillations, a kind of damping is introduced by replacing the

gas pullthrough version of Equation (14)

Wf* = Wr'-f [ a1%c] J(26)

by expressions involving an artificially large negative dependence of the choked liquid

flowrate upon the junction gas area fraction.

Let XR be the static quality corresponding to afj and let RP be that corresponding

a0qP (calculated from the extended correlations as used in previous Sections). The

damping is applied if xn<2.5 10-3 or P <2.5 10-3. In this case the junction liquid

flowrate WfP is assumed to depend on RP according to

Wf = C (5 10-"-XP) (27)

The "constant" C is chosen such that at the static quality XD the liquid flowrate calculated using the current liquid velocity vf matches that given by Equation (27). The

static quality RD is the minimum of 2.5 10-3 and Xn.

A partial derivative DWfP/Dccf-P is evaluated from Equation (27) assuming that the

i-P only dependence is due to the X term. This derivative is then used in Equation (26)

in place of aWf/•)ari.

AEA-TRS-1050 - 14-
5. PROGRAMMING DETAILS

5.1. New Variables

Six new global array variables have been added to the junction block:

VODFJO

This is the old junction liquid area fraction afr". The existing variable VOIDFJ cannot be used because it is overwritten before the HSE calculation is performed.

VODGJO

This is the old junction gas area fraction ocjn. The existing variable VOIDGJ cannot

be used because it is overwritten before the HSE calculation is performed.

VDFJOO

This is the old junction liquid area fraction from the previous timestep. It is necessary because when a timestep is restarted the junction properties routine JPROP is

called to recalculate the old junction variables from saved old volume variables.

VDGJOO

This is the old junction gas area fraction from the previous timestep.

VELFO

This is the old volume average liquid velocity.

VELGO

This is the old volume average gas velocity.

The number of junction variables in a parameter statement in the junction block is incremented by six.

5.2. Input Routines

No change. It should be noted that the release 5m5 has been changed compared to the

pre-release version 411 for which this section applies. In particular it appears that pipe

intemal junctions are forced to have a value zero for the junction control flag "v" which

denotes the junction orientation. The input data description does not state whether this

means that the HSE model cannot be invoked (which is unduly restrictive) or whether it is

invoked but as a central off-take orientation only.

5.3. Output Routines

No change.

AEA-TRS-1050 - 15 -
5.4. Initialisation Routines

The changes described in this section were all made to the pre-release version 411. The

release version 5m5 has changes to the input junction control flag "v" which denotes the

junction orientation. The associated coding changes made by EG&G have not been studied by the author.

ICMPNI

For the original RELAP5/MOD2 HSE model, all junction geometries involving no

significant area reduction between the horizontal volume and the off-take volume revert to the donor model for junction phase area fractions. For efficiency this is

hardwired into subroutine ICMPN I. However for the new model described in this paper, upward ar.,d downward off-takes do not revert to the donor model in these

geometries. Thus ICMPNI was altered to allow these two types of off-take to use the

new HSE model.

UPROP

The new variables VDFJOO and VODFJO are initialised at the end of this routine to

the initial junction value VOIDFJ (normally a donor value) calculated in the routine.

Similarly VDGJOO and VODGJO are initialised to VOIDGJ. Currently

RELAP5/MOD3 does not use any HSE model in the initialisation of junction conditions.

5.5. Transient Routines

MOVER

This routine is called when a timestep is accepted or rejected. If a timestep is rejected then the two junction variables VODFJO and VODGJO are reset to VDFJOO and

VDGJOO respectively. Also the two volume variables VELF and VELG are reset to

VELFO and VELGO respectively. If a timestep is accepted then VDFJOO and

VDGJOO are updated to VODFJO and VODGJO, VODFJO and VODGJO are updated to VOIDFJ (oa-j at this stage) and VOIDGJ (axs) respectively. Also the two

volume variables VELFO and VELGO are updated to VELF and VELG respectively.

HZFLOW

This is the routine that calculates the phase area fractions given by the HSE model for

the junction phase flows that satisfy the model conditions. The new HSE model

described in this report cannot be incorporated simply by following the existing routine logic because the new model can be in effect in flow conditions and geometries

for which the old RELAP5/MOD2 model is not. The following pseudo-coding shows

the essential part of the overall routine logic. The block IF levels have been numbered to aid in matching this logic to comments in the code source.

AEA-TRS-1050 -16-
***This is a comment

***Enter routine with c% and oxgi set to donor volume values

IF ( HSE model not allowed ) EXIT

***consider liquid entrainment

IF ( notzero gas velocity ) THEN * 0

IF ( counter current OR not downward off-take ) THEN ***

LET off-take_volume = gas-_downstream.volume

LET upstream volume = gasupstream.volume

IF ( upstreamvolumetwo-phase[cXK>0 AND afK>0] ) THEN *** 2

IF ( upstreamvolumehorizontal ) THEN *** 3

IF ( off-take area-smaller OR not side off-take ) THEN *** 4

IF ( counter current OR upward-off-take OR

(side off-take AND upstream volume>half empty ) ) THEN *** 5

***liquid entrainment section

IF ( allowed-upstream_void-range ) THEN *** 6

IF ( allowedupstreamvolume_mass_.flux ) THEN *** 7

( Calculate ctj, using new model}

IF ( co current ) THEN ***8

LET %=j- I -atgi

EXIT

ENDIF *** 8

ENDIF *** 7

ENDIF *** 6

ENDIF * 5

ENDIF ***4

ENDIF *** 3

ENDIF *** 2

ENDIF *** I

IF ( co.current AND (upward off-take OR

( side off-take AND upstream._volume>half empty) ) ) EXIT

ENDIF *** 0

***consider gas pullthrough

IF ( notzeroliquid velocity ) THEN I 1

LET off-take volume = liquiddownstream volume

LET upstream n.volume = liquid-upstream volume

IF ( upstreamvolume two-phase[ozK >0 AND CaSK>0] ) THEN

IF ( upstreamvolume horizontal ) THEN *** 2

IF ( off-takearea-smaller OR not-side off-take ) THEN *** 3

***gas pullthrough section

IF ( allowed.upstream_void-range ) THEN *** 4

IF ( allowedupstream.volume_massflux ) THEN *** 5

( Calculate %.fj using new model }

IF ( co current ) THEN *** 6

LET ctgi = -afj

ENDIF *** 6

ENDIF *** 5

ENDIF *** 4

AEA-TRS-1050 -17-
ENDIF *** 3

ENDIF *** 2

ENDIF *** 1

ENDIF *** 0

AEA-TRS-1050 - 18-
6. PROGRAM TESTING

A simple test problem was used to verify the coding (in pre-release version 411) of the correlations. A time dependent volume was connected by a 1 sq cm test junction to a 206mm diameter horizontal volume. This volume discharged into a time-dependent volume at a fixed

pressure of 0.1 MPa. The supplying volume fluid was kept at a fixed pressure of 0.7 MPa but

its quality was swept from zero to unity in a sequence of ramps. The flow rate was determined by choking in the test junction. This simple three volume system was repeated three

times to cover the three different possible orientations of the test junction: upwards, sideways

and downwards. Thus the coded HSE correlations were swept over the complete range of

liquid levels for co-current flow.

To automate the verification process, the RELAP5 control logic was used to calculate the

code's values of the off-take flow qualities (flow quality was not an output variable for prerelease version 411 of the code for which the test input was developed) obtained with the

HSE model enabled. The RELAP5 control logic was also used to calculate the off-take qualities directly by simulating the HSE correlations. This simulation took account of the

modifications to the correlations to handle large critical depths and the critical depth

modification for side off-takes given just after Equation (11). As such it will not give the

off-take flow quality arising from the correlations alone. The modifications were included to

minimise the differences to be expected in the comparison. The data is given in Appendix A.

It has been modified to run on the release version 5m5 of the code. (The data needed changing because of a change in definition of the junction flags).

The two independent calculations, from the junction properties (determined by the HSE

model) and from control system HSE simulation, of the off-take flow quality are compared

graphically in Figures 1-6. These figures were produced by running the released code, version

5m5, on a Sun SPARCstation 1. Figures I and 2 show the up case, ie with upward oriented

junction. Figure 1 shows the flow quality calculated from the junction properties, the control

system simulated flow quality and the height ratio R (distance h of liquid level from off-take

divided by the critical height hb) plotted against time. Figure 2 shows the two flow qualities

plotted against the height ratio R. The two qualities are indistinguishable despite transient

effects. The plotting utility used to generate these figures was also used to calculate and plot

the flow quality from the junction and volume properties assuming there was no HSE effect.

During the period of interest, this quality was virtually zero.

Figures 3 and 4 show the side case, ie with side or central oriented junction. Figure 3 shows

the flow quality calculated from the junction properties, the control system simulated flow

quality and the height ratio R (height h of liquid level above the off-take divided by the critical height hb) plotted against time. Figure 4 shows the two flow qualities plotted against the

height ratio R. The two qualities are barely distinguishable except around the zero height ratio area. The difference here is due to the finite off-take area modification. Also plotted is

the off-take flow quality calculated assuming there was no HSE effect. During the period of

interest, this quality was virtually zero.

AEA-TRS-1050 - 19-
Figures 5 and 6 show the down case, ie with downward oriented junction. Figure 6 shows the

flow quality calculated from the junction properties, the control system simulated flow quality

and the height ratio R (distance h of liquid level from off-take divided by the critical height

hb) plotted against time. Figure 6 shows the two flow qualities plotted against the height ratio R. The two qualities were more distinguishable in this case than the up case. This is

thought to be due to transient effects. The flow quality is changing significantly over a short

time period. Also plotted is the off-take flow quality calculated assuming there was no HSE

effect. In this case, during the period of interest, this quality was greater than that of the HSE

model.

This test verified the coding of the correlations.

During this testing, a run was performed in which the flow area of the discharge junctions

(downstream of the test junctions) was set to 5.0 10-5. This showed numerical oscillations in

the test junctions at high qualities. These oscillations persisted even when the test junction

flow was single phase steam. It was also noticed that the slip was oscillating. This suggests

that the problem is associated with a model other than the HSE model.

AEA-TRS-1050 - 20 -
7. CONCLUSION

This report has described the numerics and implementation details for the modification of

RELAP5/MOD3 to use the HSE correlation set described in Reference [1]. These details include the areas where the use of the HSE correlation set has been extended outside of its

range. The modifications, which were incorporated into pre-release code version 411, remain

in the first "frozen" release of the code (version 5m5). Areas where changes have been made

by EG&G in producing the release version which might affect the modelling have been noted

in the section on programming details. Particularly noteworthy is the restriction which apparently excludes the full control of the HSE model at the internal junctions of PIPE components.

A simple test problem was used to verify the RELAP5/MOD3 coding of the correlations, making use of the control system logic. This problem was run using the release code version. It

was noted that this version seemed to be more prone to instability than the pre-release version

411. The problem is not believed to be associated with the HSE model.

AEA-TRS-1050 - 21 -
REFERENCES

1. Ardron, K H, Bryce, W M. Assessment of Horizontal Stratification Entrainment Model

in RELAP5/MOD2. AEEW-R 2345. April 1988.

AEA-TRS-1050 - 22 -
tnj

0

Ln

0

(A

THE FOLLOWING ARE PLOTTED AGAINST Time

Control Component No,FROM VOL/JN PROPS

1WInFrith

KEY

SYM NAME UNITS

BOL

-4-- Control Component No,

FLOW X FROM JN. PROPS.

LOC- 204/ 0/ 0 MNEM-CCNO INF=l

-4- Control Component No,

FLOW X CONTROL SYS. HSE CALC.

LOC- 255/ 0/ 0 MNEM-CCNO INF-I

-4- Control Component No,

R (*REIGHT* RATIO)

LOC- 243/ 0/ 0 MNEM-CCNO INF=I

-4-- FROM VOL/JN PROPS

FLOW X WITH NO HSE MOD.

0

w.

Cd

ca

bg

Time SECONDS

SIMPLE HSE TEST CASES RELAP5/MOD3 5M5 SUN SPARC 1

FIGURE 1 TEST ENTRALLC - UP CASE FLOW QUALITY
0

0

1)

THE FOLLOWING ARE PLOTTED AGAINST Control Component No

Control Component No,FROM VOL/JN PROPS

[WInfrith,

KEY

SYM NAME UNITS

BOL

-I-- Control Component No,

FLOW X FROM JN. PROPS.

LOC- 204/ 0/ 0 MNEM-CCNO INF-l

-2-- Control Component No,

FLOW X CONTROL SYS. HSE CALC.

LOC- 255/ 0/ 0 MNEM-CCNO INV=l

1

0.8

0.6

-4- FROM VOL/JN PROPS

FLOW X WITH NO HSE MOD. Ed

a:

0

C..

Cd

Cd

Cd

U)

0.4

0

0

1.0

Control Component No ,

LOCATION 243/ 0/ 0

SIMPLE HSE TEST CASES RELAP5/MOD3 5M5

FIGURE 2 TEST ENTRALLC - UP CASE FLOW

SUN SPARC 1

QUALITY
:Do

0

U,1

0

fQ

THE FOLLOWING ARE PLOTTED AGAINST Time

Control Component No,FROM VOL/JN PROPS

IWin fri1thl

KEY

SYH NAME UNITS

BOL

-4- Control Component No,

FLOW X FROM JN. PROPS.

LOC- 212/ 0/ 0 MNEM-CCNO INF-1

-.2- Control Component No,

FLOW X CONTROL SYS. HSE CALC.

LOC- 270/ 0/ 0 MNEM-CCNO INF-l

-3--Control Component No,

R ("HEIGHT* RATIO)

LOC- 247/ 0/ 0 MNEM-CCNO INF=l

-.4- FROM VOL/JN PROPS

FLOW X WITH NO HSE MOD.

e.1 V

0 C4.

b4C -0

C-3

-0

-0

-1

Time , SECONDS

SIMPLE ElSE TEST CASES RELAP5IMOD3 5M5 SUN SPARC I

FIGURE 3 TEST EHTRALLC - SIDE CASE FLOW QUALITY
0

I-n

0

0-I

THE FOLLOWING ARE PLOTTED AGAINST Control Component No

Control Component No,FROM VOL/JN PROPS

IW n Fr 17h]

KEY

SYB B0L NAME UNITS

---- Control Component No,

FLOW X FROM JN. PROPS.

LoC- 212/ 0/ 0 MNEH-CCNO INF-=

--2- Control Component No,

FLOW X CONTROL SYS. HSE CALC.

LOC- 270/ 0/ 0 MNEM-CCNO INF=l

-4- FROM VOL/JN PROPS

FLOW X WITH NO HSE MOD.

cd

(2

Control Component No ,

LOCATION 247/ 0/ 0

SIMPLE HSE TEST CASES RELAP5/MOD3 5M5 SUN SPARC 1

FIGURE 4 TEST ENTRALLC - SIDE CASE FLOW QUALITY
I'3

0

Ln

0

THE FOLLOWING ARE PLOTTED AGAINST Time

Control Comp•onent No,FROM VOL/JN PROPS

1winfrithl

KEY

SYH NAME UNITS

BOL

-I--. Control Component No,

FLOW X FROM JW. PROPS.

LOC- 208/ 0/ 0 Mt!M-CCIO INF.l

-2- Control Component No,

FLOW X CONTROL SYS. HSE CALC.

LOC. 283/ 0/ 0 MH!M-CCNO iNF1-i

-.3-- Control Component No,

R (OHEIGHT" RATIO)

LOC- 244/ 0/ 0 tHEM-cCNO INF.1

-- +- FROM VOL/IN PROPS

FLOW X WITH NO HSE MOD.

1.0

0.8

.- 0.6 .4

W

S 0.4 cd

0.2

0.0

110

Time ,SECONDS

SIMPLE HSE TEST CASES RELAP5/MOD3 5M5 SUN SPARC 1

FIGURE 5 TEST ENTRALLC - DOWN CASE FLOW QUALITY
cLn

0

00

I

0,

THE FOLLOWING ARE PLOTTED AGAINST Control Component No

Control Component No,FROM VOL/JW PROPS -

WinfNth

KEY

SYM NAME UNITS

BOL

-I- Control Component No,

FLOW X FROM JN. PROPS.

LOC, 208/ 0/ 0 MNEM-CCNO INF-1

-2-- Control Component No,

FLOW X CONTROL SYS. HSE CALC.

LOC- 283/ 0/ 0 MNEM-CCNO INF-1

-4-- FROM VOL/JN PROPS

FLOW X WITH NO HSE MOD. co

0e

ca2

C.a

f.,

Control Component No

LOCATION 244/ 0/ 0

SIMPLE HSE TEST CASES RELAP5/MOD3 5M5 SUN SPARC 1

FIGURE 6 TEST ENTRALLC - DOWN CASE FLOW QUALITY
Appendix A. Test Data Listing

The following is a listing of the test data for RELAP5/MOD3 release version 5m5:

wentrallc entrainment model test all voids and orientations (choking) a

*$*a~$a$*$.$a$*$*$*$*$*$*$*$*$a$$*

switch on hse option for mod2

as$*$aS$S$*$*$*$*$*$$*$*$*$$a$*$*$

0000100 new transnt

0000105 1.0 2.0

*$*$*$*$*$*$*$*$*S$$*$*$*$*$*$*$*$

* time step control cards

a end time min dt max dt optn

asssas.s*sa$.s$ss-ass~s$a;*$*$ *$a$

0000201 110.0 1.O-7 0.10 1603 a$*$a$*$a$'$*$*$a$'$a$*$a$*$a$*$a$

* minor edit variables

*$*$*$*$*$*$*$*$*S$*$*$*$*$*$*$*$$

0O00347

0000348

0000349

0000350

0000351

0000352

0000353

0000354

0000355

0000356

0000357

0000358

extras

voidg 128010000

mflowj 12700(X)O0

velfj 127000000

velgj 127000000

cntrlvar 209

cntrlvar 210

cntrlvar 234

cntrlvar 235

cntrlvar 242

ontrlvar 247

cntrlvar 212

ontrivar 270

a side branch void fraction a side branch junction flow

a side branch liquid velocity

a side branch steam velocity

" side branch steam flow

a side branch liquid flow

a aide branch cm low height

a side branch cm high height

a side branch liq height

a aide branch height ratio

a side branch flow quality

a side branch check quality

mnr mjr rat

3 100 1000

0000301 p 104010000

0000302 p 108010O00

0000303 quals 104010000

0000304 qualm 108010000

0000305 voidgj 107000000

0000306 voidg 104010000

0000307 voidg 108010000

0000308 mflowj 107000000

0000309 velij 107000000

0000310 velgj 107000

0000311 cntrlvar 201

0000312 cntrlvar 202

0000313 cntrlvar 232

0000314 cntrlvar 240

000315 cntrlvar 243

0000316 cntrlvar 255

0X)00317 cntrlvar 204

0000318 cntrlvar 255

318 quale 108010000

0000321 p 114010000

0000322 p 118010000

0000323 quals 114010000

0000324 quals 118010000

0000325 voidgj IIO7000

0000326 voidg 114010100

0000327 voidg 118010000

0000328 mflowj 117000000

0000329 velfj 11700(0000

0000330 velgj 117000000

0000331 cntrlvar 205

0000332 cntrlvar 206

0000333 cntrlvar 233

00003.A4 entrlvar 241

0000335 cntrlvar 244

0000336 cntrlvar 283

0000337 cntrlvar 208

0000338 cntrlvar 283

a pipe pressure a upward branch pressure

a pipe static quality

a upward branch static quality

a upward branch Jun void fractn

a pipe void fraction

a upward branch void fraction

a upward branch junction flow

a upward branch liquid velocity

a upward branch steam velocity

a upward branch steam flow

a upward branch liquid flow

a upward branch cm distance

a upward branch liq distance

a upward branch distance ratio

a upward branch check quality

a upward branch flow quality

a upward branch check quality

a pipe pressure

a downward branch pressure

a pipe static quality

" downward branch static quality

a downward branch Jun void fractn

a pipe void fraction

a downward branch void fraction

a downward branch junction flow

a downward branch liquid velocity

a downward branch steam velocity

a downward branch steam flow

a downward branch liquid flow

a downward branch cm depth

a downward branch lIq depth

a downward branch depth ratio

a downward branch check quality

a downward branch flow quality

a downward branch check quality

20800001 dt 0

20800002 dtcmt 0

20800003 xej 107(000000

20800004 xej 117000000

20800005 xej 127000000 it'*$*$*$**$**$*$*$*$*$*$*$*$*$*$*$

a hydraulic data

a main pipe for upward connection

1040000 supup tmdpvol

a varea vlen vvol h-ang

1040101 0.0333 1.0 0.0 0.0

v-ang v-ht

0.0 0.0

a rough

1040102 0.0

a ic-ind

1040200 006

a search

1040201 0.0

1040202 5.0

1040203 55.0

1040204 60.0

a ic-ind

1040200 002

a search

1040201 0.0

1040202 5.0

1040203 7.5

1040204 10.0

1040205 15.0

1040206 20.0

1040207 25.0

1040208 30.0

1040209 35.0

1040210 40.0

1040211 45.0

hy-diam vflags

0.0 10

press uliq ugas voidg qualm

0.70e6 6.8852e5 2.56951e6 I.Oc-8 0.0

0.70e6 6.8852e5 2.56951e6 I.Oe.8 0.0

0.70e6 6.8852e5 2.56951e6 1.0 0.0

0.70e6 6.8852c5 2.56951e6 1.0 0.0

press qual

0.70e6 0.0

0.70e6 0.0

0.70e6 9.9790e-5

0.70e6 2.048 I.e-4

0.70e6 4.322ge-4

0.70e6 6.8638e-4

0.70e6 9.7210e-4

0.70e6 1.2957c-3

0.70e6 1.6653e-3

0.70e6 2.0914,-3

0.70e6 2.5881e-3

0000341

0000342

0000343

0000344

0000345

0000346

p

p

quals

quals

voidgj

voidg

124010000

128010000

124010000

128010000

127000000

124010000

* pipe pressure a aide branch pressure

a pipe static quality

a aide branch static quality

a side branch jun void fractn

a pipe void fraction

AEA-TRS-1050 - 29 -
1040212 50.0 0.70e6 3.1744e-3

1040213 55.0 0.70e6 3.8771e-3

1040214 60.0 0.70e6 4.7346e-3

1040215 65.0 0.70e6 5.8044e-3

1040216 70.0 0.70e6 7.1765e-3

1040217 75.0 0.70e6 9.00O0e-3

1040218 80.0 0.70e6 1.1542e-2

1040219 85.0 0.70e6 1.5330e-2

1040220 90.0 0.70e6 2.1580e-2

1040221 95.0 0.70e6 3.3844c-2

1040222 100.0 0.70e6 6.8859e-2

1040223 102.5 0.70e6 1.3179e-!

1040224 105.0 0.70e6 1.0

1040225 110.0 0.70e6 1.0

1040226 112.5 0.70e6 1.3179e-1

1040227 115.0 0.70e6 6.8859e-2

1040228 120.0 0.70c6 3.3844e-2

1040229 125.0 0.70e6 2.1580c-2

1040230 130.0 0.70e6 1.5330c-2

1040231 135.0 0.70e6 1.1542e-2

1040232 140.0 0.70e6 9.0000e-3

1040233 145.0 0.70e6 7.1765e-3

1040234 150.0 0.70e6 5.8044e-3

1040235 155.0 0.70e6 4.7346e-3

1040236 160.0 0.70e6 3.8771e-3

1040237 165.0 0.70e6 3.1744e-3

1040238 170.0 0.70e6 2.5881e-3

1040239 175.0 0.70e6 2.0914e-3

1040240 180.0 0.70e6 1.6653e-3

1040241 185.0 0.70e6 1.2957c-3

1040242 190.0 0.70e6 9.7210e-4

1040243 195.0 0.70e6 6.8638e-4

1040244 200.0 0.70e6 4.322ge-4

1040245 205.0 0.70e6 2.048le-4

1040246 210.0 0.70c6 9.9790e-5

1040247 215.0 0.70e6 0.0

1040248 220.0 0.70e6 0.0

* upward test junction

1070000 testu angljun

a from to area loss-f loss-r

1070101 104000X000 10800000• I.Oc-4 0.0

ic-ind I-flow g-flow int

1070201 I 0.0 0.0 0.0 a

*s$*$*$a*$*$'s$*$*$*$a$*$**$*$$*$s

* upward sink time dependent volume

1100000 sink tmdpvol

0 varca vkn vvol h-ang v-ang v-ht

1100101 l.0e5 1.0 0.0 0.0 0.0 0.0

* rough hy-diam vflsgs

1100102 0.0 0.0 10

* k-ind

1100200 004

1100200 002

* search

1100201 0.0 a search

1100201 0.0

press temp quala

O.lOe6 293.0 l.Oe-2

press quale

O.lOe6 0.9

a$*$*$*$*$*$*$*$*$*$*$*$*$*$*$*$*$

a main pipe for downward connection

1140000 supdown tmdpvol a varea vlen vvol h-ang

1140101 0.0333 1.0 0.0 0.0 a rough hy-diam vflags

1140102 0.0 0.0 10 a ic-ind

1140200 006

a search press uliq ugas v

1140201 0.0 0.70c6 6.8852e5 2.569:

1140202 5.0 0.70c6 6.8852e5 2.569

1140203 55.0 0.70e6 6.8852e5 2.569

1140204 60.0 0.70e6 6.8852W5 2.569 a ic-ind

1140200 002 a search press qual

1140201 0.0 0.70e6 0.0

1140202 5.0 0.70c6 0.0

1140203 7.5 0.70e6 9.9790c-5

1140204 10.0 0.70e6 2.048 le-4

1140205 15.0 0.70c6 4.3228e-4

I140206 20.0 0.70e6 6.8638h-4

1140207 25.0 0.70c6 9.7210c.4

1140208 30.0 0.70e6 1.2957c-3

1140209 35.0 0.70c6 1.6653c-3

10100 1140210 40.0 0.70e6 2.0914e-3

1140211 45.0 0.70e6 2.588 1e-3

1140212 50.0 0.70e6 3.1744e.3

1140213 55.0 0.70e6 3.877le-3

1140214 60.0 0.70e6 4.7346e-3

1140215 65.0 0.70e6 5.8044e-3

1140216 70.0 0.70e6 7.1765e-3

1140217 75.0 0.70e6 9.00e-3

1140218 80.0 0.70e6 1.1542e-2

1140219 85.0 0.70e6 1.5330e-2

1140220 90.0 0.70e6 2.1580e-2

1140221 95.0 0.70c6 3.3844e-2

1140222 100.0 0.70e6 6.8859e-2

1140223 102.5 0.70e6 1.3179e-I

1140224 105.0 0.70e6 1.0

1140225 110.0 0.70e6 1.0

1140226 112.5 0.70e6 1.3179c-I

1140227 !15.0 0.70c6 6.8859e-2

1140228 120.0 0.70e6 3.3844c-2

1140229 125.0 0.70e6 2.1580eo2

v-mgi v-hit

0.0 0.0

oidg quala

51e6 l.Oe-8

5le6 I.Oe-8

51e6 1.0

51e6 1.0

0.0

0.0

0.0

0.0

fvcahs

0.0

v-ht

0.0

aa*$S$*$*$*$S*$*$*$'$*$*$*$*$*$*$*

a upward branch pipe

1080000 off-pu snglvol a vasea vlen wvol h-ang

1080101 3.1416e-2 10.0 0.0 0.0 a rough hy-diam vflags

1080102 5.0e-5 0.0 00 a kc.ind press qual

1080200 002 0.1 le6 0.01

*$****************

v-ang

0.0

a upward throttle valve

1090000 throttlu angljun

a from to area os-f Ioss-r fvcahs

$$$$ vcahs v flag changed on next card

1090101 108010000 110000000 0.0 0.0 0.0 00100

*%%% vcahs flag w6 now fvcahs & v has changed

a ic-ind l-flow g-flow int

1090201 1 0.0 0.0 0.0

AEA-TRS-1050 - 30 -
11402.0

1140231

1140232

1140233

11402.4

1140235

1140236

1140237

1140238

1140239

1140240

1140241

1140242

1140243

1140244

1140245

1140246

1140247

1140248

0

130.0

135.0

140.0

145.0

150.0

155.0

160.0

165.0

170.0

175.0

180.0

185.0

190.0

195.0

200.0

205.0

210.0

215.0

220.0

0.70e6

0.70e6

0.70e6

0.70e6

0.70e6

O.70e6

0.7Oe6

0.70e6

O.70e6

0.70e6

0.70e6

0.70e6

O.70e6

0.70e6

0.70e6

0.70c6

0.70c6

0.70e6

O.70c6

i.5330c-2

1.1542e-2

9.00OOe-3

7.1765e-3

5.8044e-3

4.7346e-3

3.877 Ie-3

3.1744e-3

2.588 Ie-3

2.0914e-3

1.6653e-3

1.2957c-3

9.72I0e-4

6.8638e-4

4.3228c-4

2.048 le-4

9.9790e-5

0.0

0.0

*$s$SaS*$SaS*S*S*~S*S*s$*S*s$aS*

* downward test junction

1170000 tesrd angijun

0 from to area losm-f

1170101 114000000 118000000 I.Oe-4

0 ic-ind I-flow g-flow Int

1170201 1 0.0 0.0 0.0 ak

*ss$a$*$*$*$*$*$*$*$*$*$*$*$a$**$*

Ioss-r fvcahs

0.0 0.0 20100

a downward branch pipe

1180000 off-pd anglvol

a varea vlen vvol

1180101 3.1416c-2 10.0 0.0

a rough hy-diam vflags

!110102 5.Ne-5 0.0 00

a ic-ind press qual

1180200 002 0.1le6 0.01

1240000 supxide tmdpvol

varea vlen vvol h-ang

1240101 0.0333 1.0 0.0 0.0

a rough hy-diam vflaga

1240102 0.0 0.0 10 a ic-ind

1240200 006 a search press uliq ugas

1240201 0.0 0.70e6 6.8852e5 2.

1240202 5.0 0.70e6 6.8852e5 2.'

1240203 55.0 0.70e6 6.8852e5 2.

1240204 60.0 0.70e6 6.8852e5 2.

* ic-ind

1240200 002

s aearch press qual

1240201 0.0 0.70e6 0.0

1240202 5.0 0.70e6 0.0

1240203 7.5 0.70e6 9.9790e-5

1240204 10.0 0.70e6 2.0481e.4

1240205 15.0 0.70e6 4.3228e-4

1240206 20.0 0.70e6 6.8638e-4

1240207 25.0 0.70c6 9.7 2 1Oe- 4

1240208 .30. 0.70e6 I.2957c-3

1240209 35.0 0.70e6 1.6653.-3

1240210 40.0 0.70e6 2.0914

c-3

1240211 45.0 0.70c6 2.588 le-3

1240212 50.0 0.70c6 3.1744e-3

1240213 55.0 0.70c6 3.8

771e-3

1240214 60.0 0.70e6 4 .7346e-3

1240215 65.0 0.70e6 5.8044c-3

1240216 70.0 0.70e6 7.1765e-3

1240217 75.0 0.70e6 9.OOOOe-3

1240218 80.0 0.70e6 1.1542c-2

1240219 85.0 0.70e6 1.5330e-2

1240220 90.0 0.70c6 2.1580e-2

1240221 95.0 0.70e6 3.3844e-2

1240222 100.0 0.70e6 6 .

8 8 59e-2

1240223 102.5 0.7 0c6 1.3179e-I

1240224 105.0 0.70e6 1.0

1240225 110.0 0.70c6 1.0

1240226 112.5 0.70e6 1.3179c-1

1240227 115.0 0.70e6 6. 8 859c-2

1240228 120.0 0.70e6 3.3844e-2

1240229 125.0 0.70e6 2.1580e-2

1240230 130.0 0.70e6 1.5330e.2

1240231 135.0 0.70c6 1.1542c-2

1240232 140.0 0.70e6 9.0OOOe-3

1240233 145.0 0.70c6 7.1765e-3

1240234 150.0 0.7 0e6 5.8044e-3

1240235 155.0 0.70e6 4.7 34 6e-3

1240236 160.0 0.70e6 3.8771e03

1240237 165.0 0.70c6 3.1744e-3

1240238 170.0 0.70e6 2.5881e-3

1240239 175.0 0.70e6 2.0914c-3

1240240 180.0 0.70e6 1.6653e-3

1240241 185.0 0.70e6 1.2 957e-3

1240242 190.0 0.70e6 9.7210e-4

1240243 195.0 0.7 0c6 6.8638c-4

124024 200.0 0.70e6 4.3228e-4

1240245 205.0 0.70c6 2.048 1e-4

vohig quala

5695le6 I.Oe-8

5695 Ie6 I.Oe-8

5695Ie6 1.0

56951e6 1.0

0.0

0.0

0.0

0.0

v.ang v-hi

0.0 0.0

h-ang v-ang

0.0 0.0

v-ht

0.0

*$*$*$$*$*$*$*$*S$*S*$*$*$*$*$*$*$

* downward throttle valve

1190000 throttld angljun

* from to area logs-f Ioss-r fvcahs

$$ vcahs v flag changed on next card

1190101 1180100100 120000000 0.0 0.0 0.0 00100

*%%% vcaht flag w6 now fvcahs & v has changed: new w9

a k-ind I-flow g-flow int

1190201 1 0.0 0.0 0.0

a*$*$*$*$*$*$*S*Sa*$*$*$aSaS*S$*S$

a downward sink time dependent volume

1200000 sink tmdpvol

a varea vlen vvol h-ang v-ang

1200101 I.Oe5 1.0 0.0 0.0 0.0

a rough hy-diam vflags

1200102 0.0 0.0 10

a ic-ind

1200200 004

1200200 002

a search press temp quala

1200201 0.0 O.lOe6 293.0 1.Oe-2

a aearch press quale

1200201 0.0 O.lOe6 0.9

$~ai$n$pipe$*$for$side$$*$a*$$e$i$

a main pipe for aide connection

v-ht

0.0

AEA-TRS-1050 -31 -
1240246 210.0

1240247 215.0

1240248 220.0

0.70e6 9.9790e-5

0.70e6 0.0

0.70e6 0.0

a$*$*$*$*$*$*$*$.ss$s*$*$*$*$**$$s

* side test Junction

1270000 tests angljun

" from to area loss-f loss-r fvcahs

a for mod2 (uk e03)

1270101 124000000 128000000 l.Oe-4 0.0 0.0 lOOl00

" for mod3 (uk)

$$$$ vcahs v flag changed on next card

1270101 124000000 128000000 I.Oc-4 0.0 0.0 30100

*%%% vcahs flag w6 now fvcahs & v has changed; new w9

0 ic-ind 1-flow g-flow int

1270201 I 0.0 0.0 0.0

20200108 2.2124094630IOe-01 2.269952498682e-01

20200109 3.064510716225e-01 1.545084971855e-0I

20200110 4.008184178474e-01 7.821723251785e-02

20200111 5.00000X00000e-01 0.00000000000-O+00

20200112 5.991915821557e.0I .7.821723252289e-02

20200113 6.93548928380Ie-0I -1.545084971904e-0l

20200114 7.787590537009e-01 .2.269952498727e-01

20200115 8.513653457283e-01 -2.93892626149le-01

20200116 9.091549430914e-0l .3.535533905960e-0l

20200117 9.51365.3457268e-01 -4.045084971899c-0l

20200118 9.78759053698 le.I -4.455032620962e-OI

20200119 9.935489283762,-01 ..4.755282581490c-01

20200120 9.99181582151 fe-Of -4.938441702983e-0l

20200121 1.000000000000e+00 .5.0OOOOOOOe-0l -$.$-$.$a*s$*$*$s$s.$.*s-$*sas-*s$

calculators for liquid and vapour mass flows

a$s$s$s*Sa$*$a*$*s$$*s*sa$*$s$$*$'$

* upward branch

20520100 vap-uflw muir 3.1416e-2 I.Oe-20 1 1

20520101 voidgj 10700(0000

20520102 rhogj 107000000

20520103 velgj 1070(WO0 a,

*$*$*$*$a*$*$*$*$*$*$s*$a*$*$*$*s*

* side branch pipe

1280000 off-ps anglvol

* varea vlen vvol h-ang v-ang

1280101 3.1416e-2 10.0 0.0 0.0 0.0

* rough hy-diam vflags

1280102 5.0e-5 0.0 00

* ic-ind press qual

1280200 002 O.1le6 0.01

l.Oe-20

v-ht

0.0

20520200 liq-uflw

20520201 voidfj

20520202 rhofj

20520203 velr.

20520300 tot-uflw

20520301 0.0

20520302

mult 3.1416e-2 l.Oe-20

107(XX0K0

107000(KK)

107000000

sum 1.0 0.01

1.0 cntrlvar 20t

1.0 entrlvar 202

1 1 1.OC-20

as$as$a$*$s$.$s*s.*s$a$*$s$$*$a*$*

a side throttle valve

1290000 throttls angijun

0 from to area loss-f loss-r fvcahs

$$$$ vcahm v flag changed on next card

1290101 128010000 1300000*0 0.0 0.0 0.0 00100

*%%% vcahs flag w6 now fvcahs & v has changed: new w9

S Ic-ind I-flow g-flow int

1290201 1 0.0 0.0 0.0

a side sink time dependent volume

1300000 sink tmdpvol

' rares vlen vvol h-ang v-ang v-ht

1300101 I.Oe5 1.0 0.0 0.0 0.0 0.0

a rough hy-diam vflags

1300102 0.0 0.0 to

* ic-ind

1300200 004

1300200 002

a -earch press temp quala

1300201 0.0 O.lOe6 293.0 1.O-2

a search press quale

1.300201 0.0 0.10e6 0.9

a tables

*$*$*$SaS*SaS*$*$*SaSaSasS*Sa*$S

a table to relate liquid height to void fraction

20200100 reac-t 0

a void fraction height from centre

20200101 0.000000000000+00 5.OOOOOOOOOOOk-01

20200102 8.194178458320e-04 4.938441702975e-0l

20200103 6.4510716211 7 7e-03 4.755282581474e-Of

20200104 2.124094630001e-02 4.455032620938e-01

20200105 4.863465427216e-02 4.045084971869e-0l

20200106 9.084505690862e-02 3.535533905924e-O1

20200107 1A86346542727e-Ol 2.938926261450e-01

I

20520400 x-junu

20520401 cntrlvar

20520402 cntrlvar a

div

203

201

1.0 0.0 I 3 0.0 1.0

a downward branch

20520500 vap-dflw mult 3.1416e-2 1.0e-20

20520501 voidgj 11700(0000

20520502 rhogj 1 17000()0

20520503 velgj 11 70() 0)0

20520600 liq-dflw mult 3.1416e-2 1.Oe-20

20520601 voidr] 117000000

20520602 rhofj I I 7(0 )00

20520603 veilj I 17(KX )00 *

I1

II

L.Oe-20

l.Oe-20

20520700 tot-dflw sum

20520701 0.0 1.0

20520702 1.0

a

20520800 x.jund div

20520801 cntrlvar 207

20520802 cntilvar 205

1.0 0.01

cntrlvar 205

cntrlvar 206

I

1.0 0.0 1 3 0.0 1.0

a side branch

20520900 vap-sflw mult 3.1416e-2 1.Oe-20 ! I.Oe-20

20520901 voidgj 1270(0000

20520902 rhogj 12700OO00

20520903 velgj 127000000 a

AEA-TRS-1050 - 32-
2052 1000 liq-sflw muit

20521001 voidrj 12700(X0

20521002 rofj 12700000

20521003 veilfj 12700000

20521100 tot-sflw sum

20521101 0.0 1.0 c

20521102 1.0 cn

20521200 x-juns div

20521201 cntrlvar 211

20521202 cntrlvar 209

• summed phase flows

20521400 yap-flow sum

20521401 0.0 1.0 c

20521402 1.0 C

20521403 1.0 cn

20521600 lIq-flow sum

205216010.0 1.0 c

20521602 1.0 ci

20521603 1.0 cn

3.1416e-2 l.Oe-20 1 1 I.Oe.20 20522900 wgwgsp2 powerr 1.0

20522901 cntrlvar 225 0.2

0

20523000 wfwfdp2 powerr 1.0

20523001 cntulvar 226 0.2

20523100 wfwfsp2 powerr 1.0

20523101 cntrlvar 227 0.2

1.0e.20 1 1 I.Oc-20

I.Oe.20 1 1 I.Oc.20

I.Oe-2D I I I.Oe.2D

1.0 0.01

intrlvar 209

ntrlvar 210

I

1.0 0.0 I 3 0.0 1.0 20523200 hbup

20523201 0.0

sum

1.0

1.67 l.Oc-6 1 3 l.Oe-6 0.206

cntrlvar 228

20523300 hbdown sum 1.50 I.Oe-6

20523301 0.0 1.0 cntrlvar 230

1 3 1.Oe.6 0.206

1.0 0.0

ntrlvar 201

ntrlvar 205

ntrlvar 209

1.0 0.0

ntrlvar 202

ntrlvar 206

ntrlvar 210

I

I

20523400 hbsli low sum 0.69 5.64e-3 I 3 5.6 4e-3 0.103

20523401 0.0 1.0 cntrlvar 229

20523500 hbsi..hgh sum 0.75 5.64e-3 1 3 5.64e-3 0.103

20523501 0.0 1.0 cntrlvar 231

a calculators for level height

" liquid level above main pipe centre as fraction of pipe diameter

20523900 hIeId function 1.0 0.0 I 3 -0.5 0.5

20523901 voidg 104010000 001

0

20524000 hup sum 0.206 I.Oe-20 I I l.Oe-20

20524001 0.5 -1.0 cntrlvar 239

20524 I0M hdown sum 0.206 1.Oe-20 I I 1.Oe-20

20524101 0.5 1.0 cntrlvar 239

as$s$*$*$asas$*$*$*$*$*$*$*$asa*$*

• calculators for hte correlations

ass$.$*$*$*S**$a*s*$*s*$*$*s**$s-

• calculators for critical heIght/depth hb

20521700 gdrho sum 9.81 1.0 1

20521701 0.0 1.0 rhof 1040100(00

20521702 -1.0 rhog 104010000

0

20521800 wgwgu mult 1.0 l.Oe-20 1

20521801 cntrlvar 201 cntrlvar 201

20521900 wgwgs mult 1.0 l.Oe-20 I

20521901 cntrlvar 209 cntrivar 209

0

!

I

20522000 wfwfd mult

20522001 cntrlvar 206

20522100 wfwfs mult

20522101 cntrlvar 210 0

20522200 rggdrho mult

20522201 cnirlvar 217

20522300 rfgdrho mult

20522301 cntrlvar 217

20522400 wgwgund div

20522401 cntrdvar 222

20522500 wgwgnd div

20522501 cntrlvar 222

0

20522600 wfwfdnd div

20522601 cntrlvar 223

20522700 wfwfsnd div

20522701 cntrlvar 223 *I

1.0 1.Oe-20 I I

cntrlvar 206

1.0 1.Oe-20 I I

cntrlvar 210

1.0 !.0e-20 I I

rhog 104010000

1.0 1.Oe-20 I I

thof 104010000

l.Oe-20

1.Oc-20

I .Oe-20

L.Oe-20

I .Oe.20

1.Oe-20

20524200 hside

20524201 0.0

• calculators for non-dimensional height r

20524300 rnp div 1.0 1.Oe-20 1 3 1.0e-20 1.0

20524301 cntrlvar 232 cntrlvar 240

sum 0.206 0.0

1.0 cntrlvar 239

I

20524400 rdnwn div

20524401 cntrlvar 233 *

2052450 rolke I div

20524501 cntrlvar 234

0

20524A0 rxWde2 div

20524601 cntrlvar 235

6

20524700 rxide sum

20524701 0.0 1.0

20524702 1.0

1.0 1.Oe-20 1 3 0.0

cntrlvar 241

1.0

1.0 0.0

cntrlvar 242

1.0 0.0

cntrlvar 242

1.0 0.0

entrlvar 245

cntrlvar 246

I 3 -1.0 0.0

I 3 0.0 1.0

I

1.0 !.Oe-20 I I I.0e-20

cntrlvar 218

1.0 L.Oe-20 I 1

cntrlvar 219

L.OC-20

• calculators for satd quality xO

20524900 rf/rg div 1.0 1.0 1

20524901 rhog 104010000 rhof 104010000 a

1.0 1.Oe-20 I 1 I.Oe-20

cntrlvar 220

20523000 rf/rgp5 stdfnctn 1.0

2052-15001 sqrt cntrlvar 249

1.0 I

1.0 1.Oe-20 1

cntrlvar 221

I I.Oe-20

20522800 wgwgup2 powerr 1.0

20522801 cntrivar 224 0.2

I.Oe-20 I I 1.Oe-20

AEA-TRS-1050 - 33 -
205251(00 "I+svt" Rum 1.0 1.0

20525101 1.0 1.0 eatrlvar 250 a

20525200 xO div 1.15 1.0

20525201 cntrlvar 251

I

!

* calculators for upward quality x

20525300 xul sum 1.0 0.0 I 3 0.0 1.0

20525301 1.0 -1.0 cntrlvar 243

205254M0 xu2 mult 3.25 0.0 1

20525401 cntrlvar 253 cntrlvar 253

20525500 xup powerx 1.0 0.0 I 3 0.0 1.0

20525501 cntrlvar 243 cntrlvar 254

* calculators for side quality x

' calculators for xO exponents

20525600 xOsI sum 1.00 0.0 I 2 0.0

20525601 0.0 1.0 €ntrlvar 245

20525700 xOs2 sum 1.09 0.0 1 1 0.0

20525701 0.0 1.0 cntrlvar 246

0

20525800 xOs sum 1.00 0.0 1

20525801 1.0 1.0 cntrlvar 256

20525802 1.0 cntrlvar 257

20526200 "l-rs" sum 1.0 0.0 !

20526201 1.0 -1.0 cntrlvar 247

20526300 xOpl-rx powerx 1.0 0.0 1

20526301 cntrlvar 252 cntrlvar 262

0

20526400 "I+rs" sum 1.0 0.0 1

20526401 1.0 1.0 cntrlvar 247

20526500 xOtmls mult -0.5 0.0 1

20526501 cnlrlvar 247 cntrlvar 264

20526502 cntglvar 263

20526600 xOtm2s sum 1.0 0.0 1 1 0.0

20526601 1.0 1.0 cntrivar 265

20526700 xOtm3s stdfnctn 1.0 0.0 1

20526701 aqrt cntrlvar 266

20526R00 x0tn4s powerx 1.0 0.0 !

20526801 cntrlvar 252 cntrlvar 258

20527000 xside mult 1.0 0.0 1 3 0.0 1.0

20527001 cntrlvar 267 cntrlvar 268

0

20527800 "I+rd" sum 1.0 0.0

20527801 1.0 1.0 cntulvar 244

20527900 xOtmld mult -0.5 0.0

20527901 cntrlvar 244 cntrlvar 278

20527902 cntrlvar 277

0

20528000 xOtm2d sum 1.0 0.0

20528001 1.0 1.0 cntrlvar 279

0

20528100 xOtm3d stdfnctn 1.0 0.0

20528101 sqrt cntrlvar 280

20528200 xOhm4d powerx 1.0 0.0

20528201 cntrlvar 252 cntrlvar 275

20528300 xdown mult 1.0 0.0

20528301 cntrlver 281 cntrlvar

I 1 0.0

I 3 0.0 1.0

0 calculators for downward quality x 0

* calculators for xO exponent

20527500 xOd suam 2.5 0.0

20527501 0.0 1.0 cntrlvar 244

20527600 "I-rd" sum 1.0 0.0

20527601 1.0 -1.0 cntrlvar 244

20527700 x

0 pl-rd powerx 1.0 0.0

20527701 cntrivar 252 cntrivar 276

1 3 0.0 2.5

AEA-TRS-1050 - 34 -
NRC ;ORM 335 U.S. NUCLEAR REGULATORY COMMISSION I. REPORT NUMBER

12-89) (Ausloned by NRC. Add Vol.. Supp., Rev.,

NRCM 1102, SAnd Addendum Numbers. If anV.)

3201. 3202 BIBLIOGRAPHIC DATA SHEET

(S- instin.ons on the rverSe) NUREG/IA-0096

2. TITLE AND SUBTITLE

Numerics and Implementation of the UK Horizontal Stratification 3. DATE REPORT PUBLISHED

Entrainment Off-Take Model into RELAP5/MOD3 MONTH YSEAR

June 1993

4. FIN OR GRANT NUMBER

L2245

5. AUTHOR(S) 6. TYPE OF REPORT

W. M. Bryce Technical

7. PERIOD COVERED lsnclusse Oaetest

8. PERFORMING ORGANIZATION - NAME AND ADDRESS (IFNRC. proide Division. OfficeorffiRIon. U.1 Nuclear Rvgularory Commrluion, and mailing address. iI contractor, provide name andmall&e addervu.i

Physics and Thermal Hydraulics Division

AEA Thermal Reactor Services

Winfrith Technology Centre

Dorchester, Dorset

DT2 8DH, UK

9. SPONSOR ING ORGAN IZATI ON - NAM E AND ADO R ESS Of NRC. type "5ane as abover-. if contractor. provvdt NRC Division. Office or Region. U.S. Nuclear Regulatory Commission.

and mailing add•rls.

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

Washington, DC 20555

10. SUPPLEMENTARY NOTES

11. ABSTRACT (200 words or fle

This report presents the numerics and implementation details to add the same improved discharge quality

correlations into RELAP5/MOD3. In the light of experience with the modified RELAP5/MOD2 code, some of the

numerics has been slightly changed for RELAP5/MOD3. The description is quite detailed in order to facilitate

change by some future code developer. A simple test calculation was performed to confirm the coding of the

correlations implemented in RELAP5/MOD3.

12. KEY WORDSIDESCR2PTORS (List words orphroms that will ailst vvseamrhn iInlocating the reoort. 1 13. AVAILABILITY STATEMENT

ICAP Program Unlimited

RELAP5/MOD3 14. SECURITY CLASSIFICATION

UK Numerics and Implementation ITh,, Paog)

Unclassified

ithis Report,

Unclassified

15. NUMBER OF PAGES

16. PRICE

NRC FORM 335 12-891
Federal Recycling Program

NUREGAA-0096 NUMERICS AND IMPLEMENTATION OF THE UK HORIZONTAL STRATIFICATION

ENTRAINMENT OFF.TAKE MODEL INTO RELAPS/MOD3

JUNE 1993

UNITED STATES

NUCLEAR REGULATORY COMMISSION

WASHINGTON, D.C. 20555-0001

FIRST CLASS MAIL

POSTAGE AND FEES PAID

USNRC

PERMIT NO. G-67

OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE. $300

(4 copies)

Gene phee, RES

NL/N- 3 53