NUREG/IA-0238

 International 

Agreement Report

RELAP5/MOD3 Horizontal Off-Take Model for

Application to Reactor Headers of CANDU

Type Reactors

Prepared by:

Bub Dong Chung, Won Jae Lee, and Moonkyu Hwang/KAERI

Young Seok Bang, In Goo Kim, and Seung Hoon Ahn/KINS

Korea Atomic Energy Research Institute (KAERI)

150-1 Dukjin-Dong, Yuseong-Gu

Daejeon, 305-353, Korea

Korea Institute of Nuclear Safety (KINS)

19 Gusung-Dong, Yuseong,Gu

Daejeon, 305-338, Korea

A. Calvo, NRC Project Manager 

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

Washington, DC 20555-0001

June 2010 

Prepared as part of

The Agreement on Research Participation and Technical Exchange 

Under the Thermal-Hydraulic Code Applications and Maintenance Program (CAMP) 

Published by

U.S. Nuclear Regulatory Commission
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NUREG/IA-0238

RELAP5/MOD3 Horizontal Off-Take 

Model for Application to Reactor 

Headers of CANDU Type Reactors 

Manuscript Completed: May 2010 

Date Published: June 2010 

Bub Dong Chung, Won Jae Lee, and Moonkyu Hwang /KAERI 

Young Seok Bang, In Goo Kim, and Seung Hoon Ahn /KINS 

Korea Atomic Energy Research Institute (KAERI) 

150-1 Dukjin-Dong, Yuseong-Gu 

Daejeon, 305-353, Korea 

Korea Institute of Nuclear Safety (KINS) 

19 Gusung-Dong, Yuseong-Gu 

Daejeon, 305-338, Korea 

Antony Calvo, NRC Project Manager 

Prepared for:

Division of Systems Analysis 

Office of Nuclear Regulatory Research 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001
 iii 

ABSTRACT

The RELAP5 liquid entrainment and vapor pull-through models of horizontal pipe have been 

extended for the better prediction of thermal hydraulics in reactor header of CANDU plant. The 

model of RELAP5 accounts for the phase separation phenomena and computes the flux of 

mass and energy through an off-take attached to a horizontal pipe when stratified conditions 

occur in the horizontal pipe. This model is sometimes referred to as the off-take model. The 

importance of predicting the fluid conditions through an off-take in a small-break LOCA has 

been well known. In CANDU reactor, off-take model becomes so important that it controls the 

coolant flow of 95 feeders connected to the reactor header component where the horizontal 

stratification occurs. The current RELAP5 model is able to treat the only 3 directions junctions; 

vertical upward, downward, and side oriented junctions, thus improvements for the off-take 

model is needed for modeling the exact angles. The RELAP5 off-take model has been modified 

and generalized by considering the geometric effect of branching angles. Verification 

calculations have been performed for a conceptual blowdown problem in a pipe with different 

connected angles of branch. The calculated void fraction and mass flow rate of different location 

of branches shows the validity of implemented model. Experimental works have been also 

suggested for the further verification and improvement of models. 
 iv 
 v 

FOREWORD 

RELAP5 is one of the best-estimate thermal-hydraulic system codes to date. It was developed 

by United States Nuclear Regulatory Commission (USNRC) and its latest version, 

RELAP5/MOD3.3 (patch 03) was released in 2006. Though USNRC has been moving most of 

their developmental efforts from RELAP5 to TRACE, the RELAP5 code is still widely applied to 

analyses of various transients in Light Water Reactors (LWRs), including the postulated large 

break loss-of-coolant accident (LBLOCA). 

In Korea, four CANDU (CANada Deuterium Uranium)-type heavy water reactors are in 

operation, which have design peculiarities, especially the reactor core composed of many small 

separated horizontal fuel channels and the moderator separated from the coolant. For purpose 

of a regulatory auditing calculation, the RELAP5 code has been adapted to the CANDU reactor 

design by model modifications and developments. This report, as part of such an effort, 

describes how the current RELAP5 model capable of treating the only 3 directions junctions; 

vertical upward, downward, and side oriented junctions, have been modified and generalized to 

consider the geometric effect of branching angles. 

The authors acknowledge the financial support of the National Research Foundation under the 

national mid- and long-term nuclear research and development program of the Ministry of Educ

ation, Science and Technology of the Republic of Korea.
 vi 
 vii 

CONTENTS

Page

Abstract ........................................................................................................................................ iii 

Foreword ....................................................................................................................................... v 

Executive Summary ..................................................................................................................... ix 

1. Introduction ............................................................................................................................ 1-1 

2. Model Review ........................................................................................................................ 2-1 

3. Model Extension .................................................................................................................... 3-1 

4. Code and Input Card Change ................................................................................................ 4-1 

 4.1 Code Change ................................................................................................................... 4-1 

 4.2 Input Card Change ........................................................................................................... 4-1 

5. Model Verification .................................................................................................................. 5-1 

6. Concluding Remarks .............................................................................................................. 6-1 

7. References ............................................................................................................................. 7-1 

Appendices 

A Lists of Subprogram Changes ....................................................................................... A-1 

B Input deck for Model Verification ................................................................................... B-1 
 viii 

List of Figures

Figure Page

1. Schematic Diagram of CANDU Feeder and Header Arrangement ....................................... 1-2 

2. Connection angles of Feeders in Horizontal Header Pipe .................................................... 1-2 

3. Off-Take Phenomena between a Large Horizontal and Branch Pipes .................................. 2-1 

4. Discharge Flow Quality versus Liquid Depth for an Upward Off-Take Branch ...................... 2-3 

5. Discharge Flow Quality versus Liquid Depth for a Downward Off-Take Branch ................... 2-3 

6. Discharge Flow Quality versus Liquid Depth for a Horizontal Off-Take Branch .................... 2-4 

7. Conceptual Diagram for Off-Take with Connection Angle, θ ................................................ 3-2 

8. A Conceptual Problem for Model Verification ........................................................................ 5-1 

9. Header Pressure Transients ................................................................................................. 5-2 

10. Void Fractions of the Header and Each Branches ............................................................... 5-2 

11. Mass Flow Rates of Each Branches .................................................................................... 5-3 
 ix 

 

EXECUTIVE SUMMARY 

The RELAP5 liquid entrainment and vapor pull-through models of horizontal pipe have been 

extended for the better prediction of thermal hydraulics in reactor header of CANDU plant. The 

model of RELAP5 accounts for the phase separation phenomena and computes the flux of 

mass and energy through an off-take attached to a horizontal pipe when stratified conditions 

occur in the horizontal pipe. This model is sometimes referred to as the off-take model. The 

importance of predicting the fluid conditions through an off-take in a small-break LOCA has 

been well known. In CANDU reactor, off-take model becomes so important that it controls the 

reactor channel flow of 95 feeders connected to the reactor header component when the 

horizontal stratification occurs. The current RELAP5 model is able to treat the only 3 directions 

junctions; vertical upward, downward, and side oriented junctions, thus improvements for the 

off-take model is needed for modeling the exact angles. The RELAP5 off-take model has been 

modified and generalized by considering the geometric effect of branching angles. 

The variables related to the correlations and conditions in Subprogram “hzflow” were modified 

by using the relations derived from the geometry of header configuration and elevation of 

connected branch. Subprogram “rbrnch”, “rsngj”, “rvalve” were also modified for users to input 

the connection angle of branch pipes to a header, and users can apply the extended model to 

single junction, branch, and valve. 

Verification calculations have been performed for a conceptual blowdown problem with 

different connection angles of branch in a horizontal pipe. The calculated void fraction and mass 

flow rate of different location of branches shows the validity of implemented model. Since the 

model was developed by extending the existing RELAP5 side off-take model without any 

experimental validation, careful consideration should be taken into account in the amount of 

liquid entrainment and vapor pull-through. It is recommended that the branch where the 

connection angle is more than ±60o

 should be modeled with the existing upward or downward 

off-take option. Experimental works have been also recommended for the further verification 

and improvement of models. 
 x 
 xi 
1-1 

1. INTRODUCTION

The CANDU-type Pressurized Heavy Water Reactors (PHWR) have been developed by AECL 

in Canada and constructed in many countries including Korea during the past decades. At 

present time, four 600 MWe CANDU reactors [1] are operating in the Wolsung site of Korea, 

and the guarantee of safety for CANDU type reactor become more and more important. 

The efforts have been done for many years to develop a thermal hydraulic auditing code for 

CANDU-type plant by extending the model of RELAP5/MOD3 code [2]. Major thermal hydraulic 

phenomena for the key CANDU events and modeling limitation of RELAP5/MOD3 for CANDU 

applications has been identified and code improvement has been attempted [3] by extending 

existing RELAP5 models. Although many models for CANDU applications have been 

successfully implemented into the current RELAP5/MOD3.3 code [4], there are still many 

remained items related to LOCA event. One of these items is a stratification off-take model for 

CANDU reactor headers. The unique features of CANDU design are that the 190 fuel channels 

are horizontal and connected through 95 feeders to headers that distribute coolant to each 

channel. Figure 1 shows the schematic drawing of feeder connections in primary heat transport 

system of CANDU. Feeder pipes are connected with 5 orientation angles, i.e. 0-degree 

(horizontal), 36-degree, 72-degree, 108-degree, and 144 degree downward. The details are 

shown in Figure 2. 

During the hypothetical events, such as SBLOCA, the phase separation usually occurs by 

gravitational force in the reactor header which is the one of the largest horizontal pipe in 

CANDU heat transport system. One consequence of stratification in a large horizontal header 

pipe is that the properties of the fluid convected through a small flow path in the pipe wall 

depend on the location of stratified liquid level in the large pipe relative to the location of the 

branch in the header pipe wall. Since the emergency core cooling system has been designed to 

inject water into the header volume, the connected angle of feeder is important to the coolant 

flow into the fuel channel. 
 

Figure 1 Schematic Diagram of CANDU Feeder and Header Arrangement 

Figure 2 Connection angles of Feeders in Horizontal Header Pipe 

(Location F- 0, E-36, D-72, C-108, B-144 degree) 

1-2 
2. MODEL REVIEW 

RELAP5/MOD3 horizontal stratification entrainment/pull-through model [5] accounts for phase 

separation phenomena and computes the flux of mass and energy through an off-take attached 

to a horizontal pipe. The importance of predicting the fluid conditions through an off-take in a 

small-break LOCA has been discussed in detail by Zuber [6]. When stratification occurs in a 

large horizontal pipe, the quality of a branch line can be calculated by “upward off-take”, 

“downward off-take,” and “horizontal off-take” models according to connection angle between a 

large horizontal and branch pipes (Fig. 3). These models were developed from experimental 

studies where the inception height on liquid entrainment and vapor pull-through were measured. 

RELAP5/MOD3 horizontal stratification entrainment/pull-through model [5] accounts for phase 

separation phenomena and computes the flux of mass and energy through an off-take attached 

to a horizontal pipe. The importance of predicting the fluid conditions through an off-take in a 

small-break LOCA has been discussed in detail by Zuber [6]. When stratification occurs in a 

large horizontal pipe, the quality of a branch line can be calculated by “upward off-take”, 

“downward off-take,” and “horizontal off-take” models according to connection angle between a 

large horizontal and branch pipes (Fig. 3). These models were developed from experimental 

studies where the inception height on liquid entrainment and vapor pull-through were measured. 

The inception height, hb, associated with the onset of liquid entrainment or vapor pull-through is 

represented as follows [7]. 

[ ] ( ) 2.0

4.0

gfk

k

b

g

CW h − ρρρ =

 (1) 

where, k represents the phase properties of a continuum flowing in a branch pipe before the 

onset of liquid entrainment or vapor pull-through. For example, k represents liquid properties for 

downward oriented off-take. W is the flow rate of a continuum. C is a coefficient determined by 

experiment. 

Figure 3 Off-Take Phenomena between a Large Horizontal and Branch Pipes 

2-1 
⎪

⎪

⎩

⎪

⎪

⎨

⎧

−

− −

− −

−

=

for horizontal liquidtakeoff tentrianmen

for horizontal pullgastakeoff through

for downward pullgastakeoff through

liquidtakeoffupwardfor tentrianmen

C

75.0

75.0

50.1

67.1

 (2)

Experiment The correlations used for calculation of flow quality, X, at the branch entrance with 

off-take are dependent on the connection angle between a large horizontal and branch pipes, 

and represented as follows; 

( ) ( ) [ ]

( ) ( ) ( ) [ ] ⎪

⎩

⎪

⎨

⎧

+− −

+− −

−

=

+ −

−

−

X XRR horizontalafor branchtakeoff

X XRR downwardafor branchtakeoff

R branchtakeoffupwardanfor

X

R

o

CR

o

R

o

R

o

R

5.0 1 1

5.0 5.2 1

)1(25.3

15.01

15.01

 , (3) 

where, 

hb

h R =

, (4) 

5.0

1

15.1

⎟

⎠

⎞ ⎜

⎝

⎛ +

=

g

f

Xo

ρ

ρ

, 

h = distance from the stratified liquid level to junction

⎩

⎨

⎧

−

− = liquidfor tentrainmenpullgasfor through C

00.1

09.1

 . 

Figures 4, 5, and 6 show the experimental results of discharge flow quality as a function of liquid 

depth for an upward, downward, and horizontal off-take branches respectively. 

2-2 
Figure 4 Discharge Flow Quality versus Liquid Depth for an Upward Off-Take Branch 

 Figure 5 Discharge Flow Quality versus Liquid Depth for a Downward Off-Take Branch

2-3 
Figure 6 Discharge Flow Quality versus Liquid Depth for a Horizontal Off-Take Branch 

2-4 
3. MODEL EXTENSION 

Among the three RELAP5 off-take model, the side oriented off-take model was considered to be 

suitable to extend for CANDU header application. In Figure 6, the side off-take model has the 

both vapor pull-through and liquid entrainment model, and it has a correlation of relative location 

between branch and water level. The side off-take model can be easily extended for the case of 

general connection angle in Figure 7. In order to formulate the generalized off-take model, the 

followings are needed. 

1) The geometric formulation of relations between stratified water level and branch 

2) Experimental correlation of inception height, hb, associated with the onset of liquid 

entrainment or vapor pull-through at angled branch 

3) Experimental correlations used for calculation of flow quality at angled branch 

In this study, off-take model was modified to consider only the geometric configuration between 

a header and branches with any connection angles. It should be noted that original top and 

bottom off-take models in RELAP5 code was not modified. A side off-take model was extended 

to the branch with general connection angles [8]. 

Figure 7 shows the conceptual diagrams of vapor pull-through and liquid entrainment for the 

branch with angle of  to the horizon. From the Fig. 7, the void fraction, αg*, at which the liquid 

level is at the middle of the branch with the connection angle of  can be represented by the 

following equation. 

( )

π

π θ π θ π θ

α )2cos()2sin(2 * −−− − g = . (5) 

For the horizontal off-take case, that is, θ = 0, then the above equation provides αg* = 0.5. For 

the upward (θ= π/2) and downward (θ= -π/2) cases, αg* = 0.0 and αg* = 1.0 are obtained 

respectively. 

The liquid level from the branch, hc, can be obtained by the geometry. 

3-1 
( ) sinsin θ−φ= 2

D hc (6) 

Where D is diameter of pipe and φ is horizontal angle to water level on the pipe wall. The angle 

can be determined implicitly from the void fraction of header volume. 

Since there is no experimental data of angled branch, the inception height, hb was taken from 

the side off-take model. Thus nondimensional depth R, i.e. hc/hb, can be determined from Eq. (6) 

and Eq. (1). The correlation of branch flow quality is usually represented as a function of 

nondimensional depth R, as Eq. (3). Without any experimental data, the side off-take correlation 

was taken as an angled branch correlation. 

( ) ( ) ( ) [ ] XR1R5.01XX horizontalafor angled branch

5.0 R1 o CR1 o + − = +− (7) 

5.0

1

15.1

⎟

⎠

⎞ ⎜

⎝

⎛ +

=

g

f

Xo

ρ

ρ

 

⎩

⎨

⎧

−

− = liquidfor tentrainmen

pullgasfor through C

00.1

09.1

3-2 

(a) Vapor Pull-through (b) Liquid Entrainment 

Figure 7 Conceptual Diagram for Off-Take with Connection Angle, θ
4-1 

4. CODE AND INPUT CARD CHANGE 

4.1 Code Change 

The variables related to conditions in Subprogram “hzflow” were modified to implement the 

model derived from the geometrical relationship between water level and branch location, with 

the absence of experimental correlations. Since side off-take correlation was used for coding, 

extended model is not applicable to the upward and downward off-take branches. Subprogram 

“rbrnch”, “rsngj”, “rvalve” were also modified for user’s input of the connection angle of branch 

pipes. Thus users can utilize the extended model by user’s option in the component of “single 

junction”, “branch”, and valve”. Modified parts of each Subprogram are listed in Appendix A. 

4.2 Input Card Change 

In order to use the extended off-take model, single-junction geometry cards, ccc0101 through 

ccc0109, should be modified as follows. The junction data for branch and valve component 

should be also modified as similar ways. 

W6(I) Junction control flags. This word has the packed format jefvcahs . It is not necessary to 

input leading zeros. 

The digit v specifies horizontal stratification entrainment/ pull-through options. This 

model is for junctions connected to a horizontal volume. v =0 means the model is not 

applied; v =1 means an upward-oriented junction; v =2 means a downward-oriented 

junction; and v =3 means a centrally (side) located junction. v=4 means extended 

angled side located junction 

W7(R) Discharge coeff. 

W8(R) Non Eq. Factor for H-F (default = 0.14) 

W9(R) Not used in default H-F model. If W6(I) is 4, this word is the horizontal angle (degr

ee) between from-volume and to-volume
4-2 
5. MODEL VERIFICATION 

A conceptual problem, as shown in figure 8, has been set for model installation verification. 

Total 8 branches are connected to a header with different connection angles (from 0 to 90 

degree). Inner diameter and horizontal length of the header are 1 m, and 3 m respectively. Each 

branch pipe has same inner diameter of 0.01 m. 

The header is modeled as 3 nodes. All branch junctions are connected to the middle node 

(100-2) of the header. Initially, a header pipe is full of saturated heavy water at 10 MPa 

pressure. The valves are fully open to atmosphere, and blowdown occurs at time zero. The 

input deck for the verification problem is listed in Appendix B. 

100-01 100-03

0.1 Mpa

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

-90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90

Angle (deg)

Void Fraction

100-01 100-03

0.1 Mpa

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

-90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90

Angle (deg)

Void Fraction

Figure 8 A Conceptual Problem for Model Verification 

The pressure of tank decrease and void generate as a normal process of blowdown. Since the 

water inside the tank remains on a stagnant condition, phase separation occurs and water level 

formulate. The water level decrease continuously, as a consequence of blowdown process. If 

the water level reaches the elevation of branch, liquid flow should be changed into vapor flow. 

The calculation results are shown from Fig. 9 to 11. 

The pressure of tank decrease and void generate as a normal process of blowdown. Since the 

water inside the tank remains on a stagnant condition, phase separation occurs and water level 

formulate. The water level decrease continuously, as a consequence of blowdown process. If 

the water level reaches the elevation of branch, liquid flow should be changed into vapor flow. 

The calculation results are shown from Fig. 9 to 11. 

Figure 9 shows header pressure which decreased with time. Figure 10 represents the void 

transients in the header and each branch junctions. It shows that the transition from liquid to 

vapor flow happens earlier in the top branch, and later in the branches with lower connection 

angles sequentially. The void fraction in a branch increase due to the vapor pull-through even 

before the water level reaches the elevation of the branch. On the other hand, the liquid flow is 

maintained due to the liquid entrainment model in the branch after the water level passed down 

the elevation of branch. Figure 11 shows the smooth transition of discharge flow from liquid to 

steam. From these results, it is concluded that the extended model is installed well and working 

as expected. 

Figure 9 shows header pressure which decreased with time. Figure 10 represents the void 

transients in the header and each branch junctions. It shows that the transition from liquid to 

vapor flow happens earlier in the top branch, and later in the branches with lower connection 

angles sequentially. The void fraction in a branch increase due to the vapor pull-through even 

before the water level reaches the elevation of the branch. On the other hand, the liquid flow is 

maintained due to the liquid entrainment model in the branch after the water level passed down 

the elevation of branch. Figure 11 shows the smooth transition of discharge flow from liquid to 

steam. From these results, it is concluded that the extended model is installed well and working 

as expected. 

5-1 
0 20 40 60 80 100

2.0x106

4.0x106

6.0x106

8.0x106

1.0x107

1.2x107

Pressure (pa)

Time (sec)

 Upstream Pressure

Figure 9 Header Pressure Transients 

0 20 40 60 8

0.0

0.2

0.4

0.6

0.8

1.0

0

Void Fraction

time (sec)

 Top Break

 80o

 60o

 40o

 30o

 20o

 10o

 side Break

 Upstream

Figure 10 Void Fractions of the Header and Each Branch 

5-2 
0 20 40 60 80 100

0

1

2

3

4

5

6

Mass Flowrate (kg/sec)

time (sec)

 Top Break

 80o

 60o

 40o

 30o

 20o

 10o

 Side Break

Figure 11 Mass Flow Rates of Each Branch 

5-3 
5-4 
6-1 

6. CONCLUDING REMARK 

The liquid entrainment and vapor pull-through models of horizontal pipe of RELAP5/MOD3 have 

been improved for the better prediction of thermal-hydraulic between a header and feeder pipes 

in CANDU type reactor. The improved model enables to model the connection angle between 

horizontal pipe and branch as a user input value. Model implementation has been verified 

through the calculation of conceptual blowdown problem. Since the model was developed by 

extending the existing RELAP5 side off-take model without any experimental validation, careful 

consideration should be taken into account in the amount of liquid entrainment and vapor 

pull-through. It is recommended that the branch where the connection angle is more than ±60o

should be modeled with the existing upward or downward off-take option. Experimental works 

should be done for the determination of inception criteria and flow quality of angled branch. 

Interference effect of vortex motion on flow discharge between many feeder branches in the 

horizontal header pipe is also an area of study for further improvements of the model. 
6-2 
7. REFERENCES

1. “CANDU System Training Course”, Presented at KAERI/NTC, Feb. 22 ~ Mar.5 (1993). 

2. Thermal Hydraulics Group “RELAP5/MOD3 Code Manual Volume 4: Models and 

Correlations”, page 3-9, Scientech, Inc. , NUREG/CR-5535 (1998). 

3. B.D.Chung, W.J.Lee, and H.S.Lim, “Development of Best Estimate Auditing Code for 

CANDU Thermal Hydraulic Safety Analysis”, KINS/HR-248, KAERI/CR-67/99 (1999). 

4. B.D.Chung, W.J.Lee, and M.K.Hwang, H.S.Lim Y.S.Bang, “Improvements of 

RELAP5/MOD3.2.2 Models for the CANDU Plant Analysis” NUREG-IA-189, USNRC, 

October (2000). 

5. W. Bryce, Numerics and Implementation of the UK Horizontal Stratification 

Entrainment Off-Take Model into RELAP5/MOD3, AEA-TRS-1050, AEEW-R 2501, 

Atomic Energy Establishment Winfrith, March (1991). 

6. N. Zuber, Problems in Modeling of Small Break LOCA, NUREG-0724, October (1980). 

7. C. Smoglie, Two-Phase Flow Through Small Branches in a Horizontal Pipe with 

Stratified Flow, KfK 3861, Kernforschungszentrum Karlsruhe GmbH (KfK), Karlsruhe, 

FRG, December (1984). 

8. B.D.Chung and Y.S.Bang, “Improvement of RELAP5/MOD3 horizontal liquid 

entrainment/ vapor pull-through model for modeling of CANDU reactor outlet and inlet 

headers”, Presented in 2002 Spring Meeting, Korean Nuclear Society (2002). 

7-1 
7-2 
Appendix A 

Lists of Subprogram Changes 

A-1 
Changes in ‘hzflow’ 

SUBROUTINE hzflow(ichoke) 

!define win32dvf 

!define erf 

!define fourbyt 

!define hconden 

!define impnon 

!define in32 

!define newnrc 

!define ploc 

!define sphaccm 

. 

. 

. 

INCLUDE 'voldat.h' 

! candu HDR i1 

 INCLUDE 'cons.h' 

! Local variables. 

 INTEGER i,ik,j,k,kk,kx,ky,l,ll,lx,ly,m,nmap 

 LOGICAL countc 

 REAL(8) aj,ajth,alf,alg,alphef,alpham,arfg,argf 

. 

. 

. 

PARAMETER (grvmp2=0.634d0,grvp5=3.13d0) 

 REAL(8) psinq,pcosq 

! candu HDR i1 

 REAL(8) voidgs,hangle 

! 

! Data statements. 

 DATA ighsed,ighseh,ighsex/0,0,0/ 

. 

. 

. 

! candu HDR+ 

! Consider the void fraction when free surface in on the junction (theta angle) 

! void*pi= (pi/2-theta)-sin(pi/2-theta)*cos(pi/2-theta) 

! where theta = jdissh(i) 

 hangle=jdissh(i)*pi/180.0d0 

 theta=pi/2.0d0-hangle 

 voidgs=theta-sin(theta)*cos(theta) 

 voidgs=voidgs/pi 

! candu HDR- 

! Consider liquid entrainment. 

! This is the beginning of the liquid entrainment section which 

! covers 1. Upward-oriented, 

! 2. Downward-oriented counter-current 

. 

. 

. 

! 

! candu HDR r2 

! IF(countc.or.j.eq.1.or.(j.eq.3.and.voidg( & 

! kk).gt.0.5d0))then 

 IF(countc.or.j.eq.1.or.(j.eq.3.and.voidg( & 

 kk).gt.voidgs))then 

! Calculation of stratification angle. 

 alpham=min(voidf(kk),voidg(kk)) 

 theta=htheta(alpham) 

. 

. 

. 

! For normal horizontal main (doner) volume the liquid level is 

! calculated by using the stratification angle. 

! 

! candu HDR+ r1 

! hcll=diamv(kk)*0.5d0*ctheta 

 hcll=diamv(kk)*0.5d0*(ctheta-sin(hangle)) 

 ENDIF 

! Calculate common correlation parameter for j .eq. 1 2 3 

 x00=1.15d0/(1.0d0+sqrt(rhof(kk)/ & 

 rhog(kk))) 

! 

A-2 
. 

. 

. 

! Reduce it as in old model. 

! voidx=min(voidx,0.49)*0.85 

 voidx=min(voidx,0.49d0) 

! candu HDR+ 

! move voidx to adjust hangle elevation ( it is voidf, thus 1-voidgs) 

 voidx=voidx-0.5d0+1.0d0-voidgs 

! candu HDR- 

! Test for entrainment or pullthrough. 

! This sub-section covers the liquid entrainment for side off-take when 

! the voidg.gt.0.5. Cocurrent and countercurrent with main phase (gas 

. 

. 

. 

! this subroutine. 

! candu HDR r1 

! IF(voidg(kk).gt.0.5d0)then 

 IF(voidg(kk).gt.voidgs)then 

! Voidg gt 0.5 -- liquid entrainment. 

! Calculate critical depth, limiting to a radius. 

. 

. 

. 

! 

! candu HDR r2 

! IF(.not.countc.and.(j.eq.1.or.(j.eq.3.and.voidg(kk) & 

! .gt.0.5d0))) GOTO 3000 

 IF(.not.countc.and.(j.eq.1.or.(j.eq.3.and.voidg(kk) & 

 .gt.voidgs))) GOTO 3000 

 ENDIF 

! Consider gas pull-through. 

! This is the beginning of the liquid entrainment section which 

. 

. 

. 

ELSE 

! candu HDR r1 

! hcll=diamv(kk) * 0.5d0*ctheta 

 hcll=diamv(kk)*0.5d0*(ctheta-sin(hangle)) 

 ENDIF 

! Calculate correlation parameter 

. 

. 

. 

! Reduce it as in old model. 

! voidx=min(voidx,0.49)*0.85. 

 voidx=min(voidx,0.49d0) 

! candu HDR+ 

! move voidx to adjust hangle elevation 

 voidx=voidx-0.5d0+voidgs 

! candu HDR- 

! Test for pullthrough or entrainment 

! This sub-section covers the gas pull through for side off-take when 

! the voidg.lt.0.5. Cocurrent and countercurrent with main phase (gas 

! phase) moving out of main (doner) volume are considered in this sub- 

! section. For countercurrent with main phase moving into the main 

! (doner) volume is considered in the first half section of this 

! subroutine. 

! 

! candu HDR r1 

! IF(voidg(kk).lt.0.5d0)then 

 IF(voidg(kk).lt.voidgs)then 

! Voidg lt 0.5 -- gas pullthrough 

! Calculate critical height, limiting to a radius 

. 

. 

. 

A-3 
Changes in ‘rbrnch’ 

SUBROUTINE rbrnch 

!define win32dvf 

!define erf 

!define fourbyt 

!define hconden 

. 

. 

. 

! candu HDR r1 

! IF((ist.gt.3.or..not.branch).and.(ist.ne.0.or.branch))then 

 IF((ist.gt.4.or..not.branch).and.(ist.ne.0.or.branch))then 

 ist=0 

 tfail=.true. 

 ENDIF 

IF(ick.ge.2)then 

. 

. 

. 

IF(ist.eq.3)isstratinpdat18(2,ij)=.true. 

!candu HDR+ 

 IF(ist.eq.4)isstratinpdat17(2,ij)=.true. 

 IF(ist.eq.4)isstratinpdat18(2,ij)=.true. 

!candu HDR- 

 isnpccflflg2(2,ij)=.false. 

 isdonprespvwrk15(2,ij)=.false. 

IF(icc.eq.1)isnpccflflg2(2,ij)=.true. . 

. 

. 

! The super-heated vapor discharge coeff is not used. 

! Trap the cases where there are 9 words on the card and 

! Henry-Fauske is being used so that the user does not use 

! an old critical flow model deck and get a bad non-equil. factor 

! candu HDR+ 

! We are tring to use jdissh(ij) as feeder pipe connection angles with Header 

! If ist=4 (added horizontal stratification entrainment/ pullthrough options) 

! then use "word(9) R : superheated steam discharge coeff" as connection angle(deg) 

! candu HDR- 

! candu HDR i1 

 IF(l3a(6).lt.9)xinit(9)=0.0d0 

 IF(l3d(6).ge.9.and..not.isnochokflg4(2,ij))then 

! candu HDR i1 

 IF(ist.ne.4) then 

! 

 fail=.true. 

 xinit(9)=9.87654d+99 

 WRITE(output,2333)l3d(1) 

 2333 FORMAT ('0******** Henry-Fauske only requires 8 words on', & 

 & ' card ',i10,/,10x,'Make sure you are not using', & 

 & ' a card from the original RELAP5 choked flow model') 

! candu HDR i1 

 ENDIF 

 ENDIF 

 jdissh(ij)=xinit(9) 

. 

. 

. 

IF(isstratinpdat17(2,i).and.isstratinpdat18(2,i))ihf=ihf+& 

 30000 

! candu HDR i1 

 IF(ist.eq.4) ihf=ihf+10000 

 IF(.not.isstratinpdat17(2,i).and.isstratinpdat18(2,i)) & 

 ihf=ihf+20000 

 IF(isstratinpdat17(2,i).and.(.not.isstratinpdat18(2,i))) & 

 ihf=ihf+10000 

 IF(isnochokflg4(2,i))ihf=ihf+1000 

IF(isabrareachgflg8(2,i))ihf=ihf+100 . 

. 

. 

A-4 
Changes in ‘rsngj’ 

SUBROUTINE rsngj 

!define win32dvf 

!define erf 

!define fourbyt 

!define hconden 

!define impnon 

!define in32 

!define newnrc 

!define ploc 

!define sphaccm 

!define unix 

!define noselap 

!define noextvol 

!define noextv20 

!define noextsys 

!define noextjun 

!define noextj20 

!define noparcs 

!define nonpa 

!define nomap 

!define logp 

!deck rsngj 

! 

! $Id: rsngj.ff,v 1.1 2001/02/01 23:17:28 r5qa Exp dbarber $ 

! 

! Process single junction input data. 

! 

! Cognizant engineer: rjw. 

. 

. 

. 

!CANDU HDR r1 

! IF(ist.gt.3)then 

 IF(ist.gt.4)then 

 ist=0 

 tfail=.true. 

ENDIF 

. 

. 

. 

!candu HDR+ 

 IF(ist.eq.4)isstratinpdat17(2,ij)=.true. 

 IF(ist.eq.4)isstratinpdat18(2,ij)=.true. 

!candu HDRIF(ijt.ne.0)isjetjunflg25(2,ij)=.true. 

. 

. 

. 

! candu HDR+ 

! We are tring to use jdissh(ij) as feeder pipe connection angles with Header 

! If ist=4 (added horizontal stratification entrainment/ pullthrough options) 

! then use "word(9) R : superheated steam discharge coeff" as connection angle(deg) 

! candu HDR- 

! candu HDR i1 

 IF(l3a(6).lt.9)xinit(9)=0.0d0 

 IF(l3a(6).ge.9.and..not.isnochokflg4(2,ij))then 

! candu HDR i1 

 IF(ist.ne.4) then 

! 

 fail=.true. 

xinit(9)=9.87654d+99 

 WRITE(output,2333)l3a(1) 

 2333 FORMAT ('0******** Henry-Fauske only requires 8 words on', & 

 & ' card ',i10,/,10x,'Make sure you are not using', & 

 & ' a card from the original RELAP5 choked flow model') 

! candu HDR i1 

ENDIF 

. 

. 

. 

! candu HDR i1 

 IF(ist.eq.4) ihf=ihf+10000 

A-5 
 IF(.not.isstratinpdat17(2,ij).and.isstratinpdat18(2,ij))ihf= & 

 ihf+20000 

. 

Changes in ‘rvalve’ 

1 SUBROUTINE rvalve 

2 ! 

3 ! $Id: selap.s,v 1.52.1.2 1998/07/11 20:22:11 randyt Exp randyt $ 

4 ! 

5 ! Process valve input data. A valve has the same input as a single 

6 ! junction in addition to valve data. 

7 ! Valve types available are: trip valve, check valve, inertial swing 

8 ! check valve, motor valve, servo valve and relief valve. 

9 ! 

10 ! Cognizant engineer: dmk 

11 ! 

12 IMPLICIT none 

13 INCLUDE 'cmpdat.h' 

28 ! Local variables. 

29 !CANDU r1 

30 ! INTEGER l3a(15),l3b(10),l3c(10),l3d(7),l3e(18),l3f(11),init(2,17) 

31 INTEGER l3a(15),l3b(10),l3c(10),l3d(7),l3e(18),l3f(12),init(2,17) 

32 INTEGER l3g(8),l3h(9),l3i(8),l3j(23) 

33 INTEGER lenvlv(6) 

34 REAL(8) xinit(17) 

35 EQUIVALENCE(init(1,1),xinit(1)) 

55 DATA l3e/3 * 0,12,0,1,0,0,10 * 1/ 

56 !CANDU r1 

57 ! DATA l3f/3 * 0,5,0,1,0,0,1,1,0/ 

58 DATA l3f/3 * 0,6,0,1,0,0,1,1,0,1/ 

59 DATA l3g/3 * 0,0,0,0,1,1/ 

70 !CANDU r1 

71 ! DATA lenvlv/17,19,27,26,26,35/ 

72 DATA lenvlv/17,19,27,27,26,35/ 

73 DATA vname/'motor','servo'/ 

. 

. 

. 

!CANDU HDR r1 

! IF(ist.gt.3)then 

 IF(ist.gt.4)then 

 ist=0 

. 

. 

IF(ist.eq.3)isstratinpdat18(2,ij)=.true. 

!candu HDR+ 

 IF(ist.eq.4)isstratinpdat17(2,ij)=.true. 

 IF(ist.eq.4)isstratinpdat18(2,ij)=.true. 

!candu HDR- 

!blh--------------------------------------------- 

. 

. 

. 

! candu HDR+ 

! We are tring to use jdissh(ij) as feeder pipe connection angles with Header 

! If ist=4 (added horizontal stratification entrainment/ pullthrough options) 

! then use "word(9) R : superheated steam discharge coeff" as connection angle(deg) 

! candu HDR- 

! candu HDR i1 

 IF(l3a(6).lt.9)xinit(9)=0.0d0 

 IF(l3a(6).ge.9.and..not.isnochokflg4(2,ij))then 

! candu HDR i1 

 IF(ist.ne.4) then 

! 

 fail=.true. 

 xinit(9)=9.87654d+99 

 WRITE(output,2333)l3a(1) 

A-6 
 2333 FORMAT ('0******** Henry-Fauske only requires 8 words on', & 

 & ' card ',i10,/,10x,'Make sure you are not using', & 

 & ' a card from the original RELAP5 choked flow model') 

! candu HDR i1 

 ENDIF 

 ENDIF 

. 

. 

. 

703 CALL inp2(fa(filndx(1)),init,l3f) 

704 !CANDU r1 

705 ! IF(l3f(6).eq.4.or.l3f(6).eq.5) GOTO 172 

706 IF(l3f(6).eq.4.or.l3f(6).eq.5.or.l3f(6).eq.6) GOTO 172 

707 ! Not enough data for motor valve, assume 000 trips and no table 

708 ! and continue processing. 

709 WRITE(output,3003)vtype(4),l3f(1),vtype(4) 

718 vlvslp(i)=0.0d0 

719 ! CANDU i1 

720 vlvslp(i+1)=0.0d0 

721 vlstm(i)=0.0d0 

722 vlstmo(i)=0.0d0 

. 

. 

. 

766 3009 FORMAT ('0******** Card',i10,' has negative or zero slope',1p, & 

767 & e13.5) 

768 ENDIF 

769 ! CANDU Start 

770 IF(l3f(6).eq.6) then 

771 vlvslp(i+1)=xinit(6) 

772 IF(vlvslp(i+1).le.0.0d0)then 

773 tfail=.true. 

774 WRITE(output,3009)l3f(1),xinit(6) 

775 ENDIF 

776 ELSE 

777 vlvslp(i+1)=vlvslp(i) 

778 ENDIF 

779 ! End CANDU 

780 fail=fail.or.tfail 

781 ac=iand(jc(2,ij),256).ne.0 

. 

. 

. 

! candu HDR i1 

 IF(ist.eq.4) ihf=ihf+10000 

 IF(.not.isstratinpdat17(2,ij).and.isstratinpdat18(2,ij))ihf= & 

. 

. 

. 

1080! Motor valve. 

1081 350 WRITE(output,3038) 

1082!CANDU replace part 

1083! 3038 FORMAT ('0 Jun.no.',25x,'open trip no. close trip no. table no.' & 

1084! & ,5x,'slope',9x,'initial position') 

1085! WRITE(output,3040) 

1086! 3040 FORMAT (78x,'(1.0/sec)') 

1087! WRITE(output,3041)l3c(1),opntrp(2,i),clstrp(2,i),tblnum(2,i), & 

1088! vlvslp(i),vlstm(i) 

1089! 3041 FORMAT (i10,19x,i9,5x,i9,4x,i9,10x,1p,2e14.5) 

1090! CANDU Print start 

1091 3038 FORMAT ('0 Jun.no.',25x,'open trip no. close trip no. table no.' & 

1092 & ,5x,'open slope',2x,'initial position',2x,'close slope') 

 

1093 WRITE(output,3040) 

1094 3040 FORMAT (78x,'(1.0/sec)',22x,'(1.0/sec)') 

1095 WRITE(output,3041)l3c(1),opntrp(2,i),clstrp(2,i),tblnum(2,i), & 

1096 vlvslp(i),vlstm(i),vlvslp(i+1) 

1097 3041 FORMAT (i10,19x,i9,5x,i9,4x,i9,10x,1p,3e14.5) 

1098! CANDU Print end 

1099 GOTO 400 

1100! Servo valve. 

A-7 
A-8 

1281 431 filsiz(3)=filsiz(3)+len-maxlen 

1282 ncmps(2,filndx(3))=ncmps(2,filndx(3))+len 

1283 438 CALL ftbsft(filid(3),filsiz(3),3,filndx(3)) 

1284 1000 RETURN 

1285 END SUBROUTINE rvalve 
B-1 

Appendix B 

Input Deck for Model Verification 
B-2 

= Horizontal Stratification Take Off Model 

* running type 

*----------------------- 

* option 14 : turn off constitutive relation 

*1 14 

100 new transnt 

101 run 

102 si si 

105 2. 4. 

110 nitrogen 

115 1.0 

* 

120 100010000 0.0 d2o channel 

* 

201 100. 1.0e-6 0.1 3 10 1000 10000 

*201 500. 1.0e-6 0.1 3 10 1000 100000 

*201 10. 1.0e-6 0.1 3 10 10000 10000 

*201 300. 1.0e-6 0.01 7 200 50000 50000 

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

* minor edit volumes 

*----------------------- 

*300 70.2 70.8 

301 p 100010000 

302 p 100020000 

311 voidg 100010000 

312 voidg 100020000 

313 voidg 100030000 

331 quale 100020000 

332 quals 100020000 

334 xej 101000000 

341 voidgj 101000000 

342 voidgj 102000000 

343 voidgj 103000000 

344 voidgj 104000000 

345 voidgj 105000000 

346 voidgj 106000000 

347 voidgj 107000000 

348 voidgj 108000000 

361 mflowj 101000000 

362 mflowj 102000000 

363 mflowj 103000000 

364 mflowj 104000000 

365 mflowj 105000000 

366 mflowj 106000000 

367 mflowj 107000000 

368 mflowj 108000000 

* 

*371 velgj 101000000 

*372 velgj 102000000 

*373 velgj 103000000 

*374 velgj 104000000 

*375 velgj 105000000 

*376 velgj 106000000 

*377 velgj 107000000 

*378 velgj 108000000 

* 

501 time 0 ge null 0 0.0 l 

* 

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

* Heated Section Pipe 

* 

1000000 chan1 pipe 

*1000000 chan1 canchan 
B-3 

1000001 3 

1000101 1.0 3 

1000201 0.0 2 

1000301 1.0 3 

1000401 0.0 3 

1000501 0.0 3 

1000601 0.0 3 

1000701 0.0 3 

1000801 0.0 0.0 3 

1000901 0.939 0.939 2 

1001001 100 3 

1001101 100 2 

1001201 002 10.69e6 0.0001 0. 0. 0. 3 

1001300 1 

1001301 0.0 0.0 0.0 2 

* Dj 

1001401 0.00 0.0 1.0 1.0 2 

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

1010000 jun882 valve 

1010101 100020003 200000000 0.0001 0.00 0.00 10100 

1010102 1.00 0.14 *0.0 

1010201 1 0.0 0.0 0.0 

1010300 trpvlv 

1010301 501 

* 

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

1020000 jun882 valve 

1020101 100020003 200000000 0.0001 0.00 0.00 40100 

1020102 1.00 0.14 80.0 

1020201 1 0.0 0.0 0.0 

1020300 trpvlv 

1020301 501 

* 

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

1030000 jun882 valve 

1030101 100020003 200000000 0.0001 0.00 0.00 40100 

1030102 1.00 0.14 60.0 

1030201 1 0.0 0.0 0.0 

1030300 trpvlv 

1030301 501 

* 

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

1040000 jun882 sngljun 

1040101 100020003 200000000 0.0001 0.00 0.00 40100 

1040102 1.00 0.14 40.0 

1040201 1 0.0 0.0 0.0 

*1040300 trpvlv 

*1040301 501 

* 

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

1050000 jun882 sngljun 

1050101 100020003 200000000 0.0001 0.00 0.00 40100 

1050102 1.00 0.14 30.0 

1050201 1 0.0 0.0 0.0 

*1050300 trpvlv 

*1050301 501 

* 

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

1060000 jun882 valve 

1060101 100020003 200000000 0.0001 0.00 0.00 40100 

1060102 1.00 0.14 20.0 

1060201 1 0.0 0.0 0.0 

1060300 trpvlv 
B-4 

1060301 501 

* 

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

1070000 jun882 valve 

1070101 100020003 200000000 0.0001 0.00 0.00 40100 

1070102 1.00 0.14 10.0 

1070201 1 0.0 0.0 0.0 

1070300 trpvlv 

1070301 501 

* 

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

1080000 jun882 sngljun 

1080101 100020003 200000000 0.0001 0.00 0.00 30100 

1080102 1.00 0.14 *0.0 

1080201 1 0.0 0.0 0.0 

*1080300 trpvlv 

*1080301 501 

* 

2000000 system snglvol 

* Area Length Volume ANGLE Height Rough 

2000101 0.0 20.000 1000.000 0.0 -90.0 -20.000 0.00000 

2000102 0.0 000000 

2000200 002 1.0000e5 1.00 

* 

* termination card 

.