NUREG/IA-0189

International 

Agreement Report 

Improvements of 

RELAP5/MOD3.2.2 Models 

for the CANDU Plant Analysis 

Prepared by 

B.D. Chung, WJ. Lee, KAERI 

Y.S. Bang, KINS 

Korea Atomic Energy Research Institute 

PO. Box 105 

Yusung, Daejon, 305-600 

KOREA 

Korea Institute of Nuclear Safety 

PO. Box 114 

Yuseong-Gu, Taejon, 305-600 

KOREA 

Office of Nuclear Regulatory Research 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001 

October 2000 

Prepared as part of 

The Agreement on Research Participation and Technical Exchange 

under the International Code Application and Maintenance Program (CAMP) 

Published by 

U.S. Nuclear Regulatory Commission
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I
NUREG/IA-0189

International 

Agreement Report 

Improvements of 

RELAP5/MOD3.2.2 Models 

for the CANDU Plant Analysis 

Prepared by 

B.D. Chung, WJ. Lee, KAERI 

Y.S. Bang, KINS 

Korea Atomic Energy Research Institute 

P.O. Box 105 

Yusung, Daejon, 305-600 

KOREA 

Korea Institute of Nuclear Safety 

P.O. Box 114 

Yuseong-Gu, Taejon, 305-600 

KOREA 

Office of Nuclear Regulatory Research 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001 

October 2000 

Prepared as part of 

The Agreement on Research Participation and Technical Exchange 

under the International Code Application and Maintenance Program (CAMP) 

Published by 

U.S. Nuclear Regulatory Commission
Abstract

The main purpose of this study is to develop a thermal hydraulic auditing analysis code For 

CANDU reactor by extending the model of current RELAP5/MOD3, which have been used for 

a long time as an auditing analysis tool of Light Water Reactors (IWR). The major thermal 

hydraulic phenomena for the key CANDU events and the modeling limitation of the current 

REI-AP5/MOD3 for CANDIJ applications are based on the previous study oil the applicability 

of REIAP5 code to the CAN Dt-type plants. The seven models are improved: the CANDU fuel 

channel heat transfer model; the horizontal flow regime model; the digital control model; 

ANS94-4 decay heat model; Moody critical model; motor operative valve model; and 

pressurizer spray model. The models are improved and developed on generic base, thus, they 

also could be applicable to PWR. Especially, the plutonium contribution to decay heat can be 

considered by the ANS94-4 decay heat model. The Moody critical flow model using a heavy 

water property can provide an additional capability to evaluate the conservative break flow in 

CANID) system. Simulation of different rate of opening and closing the motor valve is now 

possible when calculating the liquid relief vale behavior during transient. And the new 

pressurizer spray model can be used Ior evaluating the droplet size effect on the condensation. 

All of those improvements are verified through some assessments with simple conceptual 

problems and Marviken critical flow test. The new code is based on the REIAP5/MOD3.2.2 

gamma version, and written in FORTRAN90 language.

iii
List of Contents 

A bstract .................................................................. iii 

List of Contents ........................................................... v 

List of Tables ............................................................. vi 

List of Figures ............................................................. vi 

Executive Sum m ary ....................................................... vii 

1. Introduction ............................................................ 1 

2. Identification of Model Improvement Area .................................. 3 

3. Model Extensions and Improvements ....................................... 4 

3.1 Improvements of Reactor Kinetics Model ................................ 4 

3.2 Implementation of Moody Critical Flow Model ........................... 7 

3.3 Improvement of Horizontal Flow Regime for CANDU Fuel Channel ......... 10 

3.4 Implementation of CANDU 37 Fuel Bundle Heat Transfer Model ........... 16 

3.5 Implementation of Digital Sampling Model in Control Function ............ 23 

3.6 Improvement of Motor Operated Valve Model ........................... 25 

3.7 Implementation of Pressurizer Spray Model ............................. 27 

4. Summary and Conclusions ............................................... 30 

References ............................................................... 32 

Appendix A: Input Manual Changes for RELAP5/MOD3/CANDU ............... 33 

Appendix B: Input Decks for the Validation of Model Implementation ............ 45

v
LIST OF TABLES

"Fable I Identified Items for Model Improvement Area in RELAP5/MOI)3.2.2 -------- 3 

Table 2 Comparison of Decay Ileat Model proposed by ANS ------------------------------------ 4 

LIST OF FIGURES 

Figure I Total Power Trends after Trip (5 sec) -------------------------------------------------------- 6 

Figure 2 Decay Power Trends after Trip ---------------------------------------------------------------- 6 

Figure 3 Calculation Result of Marviken 15 ----------------------------------------------------------- 9 

Figure 4 Calculation Result of Marviken 24 ----------------------------------------------------------- 9 

Figure 5 Comparison of Critical Velocity for I lorizontal Stratification at Low 

Pressure ( I atm) -------------------------------------------------------------------------------- 13 

Figure 6 Comparison of'Critical Velocity for I lorizontal Stratification at 

I ligh Pressure ( 150 atm) ---------------------------------------------------------------------- 13 

Figure 7 Nodalization D)iagram of Sample Problem for Flow Regime Model Test --------- 14 

Figure 8 Result of I lorizontal Flow Regime in Pipe Component ------------------------------- 14 

Figure 9 Result of I lorizontal Flow Regime in CANDIJ Channel Component --------- 14 

Figure 10 Flow Regime Map for an interior subchannel 2.5 cm upstream of an end plate --- 15 

Figure I I Comparison of Cl IF data at Low Pressure ( 0. 1 M Pa) -------------------------------- 19 

Figure 12 ILogic diagram of heat transfer for liuel elements in CANDIU channel --------- 20 

Figure 13 Schematic [)iagram of Fuel [lement Configuration in CANI)DJ channel ---------- 21 

Figure 14 Nodalization of a sample heatup problem in CANDU channel ---------------------- 21 

Figure I5 i leat Transfer Coefficient in Top and Bottom Fuel Group ---------------------------- -2 

Figure 16 Sheath Temperature of Top and Bottom Fuel Group ---------------------------------- 22 

Figure 17 Comparison of Pressure with the control function of which sampling lime is 

0.05 sec and 0. 1 sec -------------------------------------------------------------------------- 24 

Figure 18 Change of Step Position ol Motor ()perated Valve -..............---------------------- 26 

F igurc 19 Droplet temperature Irends along ele ation in the PRIZIFR Component ------- 2() 

Figure 20 Pressure drop during 100 sec spray s arying droplet sizes ----------------------------- 29

vi
Executive Summary

A best estimate code for CAN)DU-type plants has been strongly requested especially in the 

Korea Institute of Nuclear Safety (KINS) in Korea for his regulatory purpose including the 

independent regulatory auditing calculation of tile major design basis accidents during tile 

licensing review and/or the safety evaluation onl the operational transients and incidents 

experienced. 

The main purpose of this study is to develop a thermal hydraulic auditing code for CANDU 

reactor by extending the model of current RELAP5/MOD3, which have been used for a long 

time a5 an auditing analysis tool of Light Water Reactors ([WR). In this study, the major 

thermal hydraulic phenomena for the key CANDU events and the modeling limitation of current 

RI'i.AP5/MOD3 for CANDIU applications obtained from the previous study were used as a 

basis for model improvement. As results, the following model improvements were attempted 

and verifications of each model were performed. 

I) Reactor Kinetics Model 

2) Critical Flow Model 

3) I lorizontal Flow Regime Model in CANDU Fuel Channel 

4) CANI)U Fuel Flement I leat Transfer Model 

5) Digital Control Component Model 

6) Motor Control Valve Model 

7) Pressurizer Component Model 

Some of the model improvement items are not only specilic to CANi)U reactor, but also 

applicable to I.WR. The reactor kinetics model has been extended to use ANS94-4 standard 

decay heat model which has one more Pu precursor than ANS79-3 standard model. The Moody 

critical flow model was added as a conventional regulatory evaluation of critical discharge for 

1%\o phase mixture. Improvements vcre also made on Critical heat Ilux (C0IF) model and 

horizontal flow regime model according to the different thermal hydratlic characteristics in 

CAND)U horizontal core bundled wilh 37 Fuel elements. Fucl element heatup model was also 

implemented for the CANI)1 specilic horizontal geometry configuration when the two phase 

stratification occurs. The digital process delay model was added in control component model to 

simulate the one of the characteristic of digital control in CANI) I plant. Motor operated valve

vii
model has been extended to have a different opening rate and closing rate as receiving 

open/close signals. iPrcssurizer spray component model ws added as a new component. Using 

this componenil, interlfacial and spray characteristics could be controlled by users input model. 

By the implementation of the models to RI-ITAP5/MOI)3.2.2 gamma version, 

R•iiAP5/MOI)3/CANI)J has been developed. The FORTRAN 77 sources were converted into 

FORITRAN90 language for the new CANI)IJ version and compiled in PC Windows operating 

environment. The installation verifications and application capabilities have been tested through 

the simple conceptual problems and Maviken critical flow tests. Although i1 has been verified in 

the conceptual basis, more extensive assessment works should be followed to examine the 

applicability for CANI)U plant analysis.

Viii
I. Introduction

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

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

present time, four 600 MWe CAN )U reactors [II are operating on the Wolsung site in Korea 

and it becomes more and more important to guarantee the safety tbr CANDU type reactor in 

both the regulatory body and the utility company. In reality, sonic incidents ranging from the 

minor transient to the I)20 leakage have been experienced in Korean CANDU plants. Based on 

this situation, a best estimate code for CANDU-type plants has been strongly requested 

especially ili the Korea Institute of Nuclear Safety (KINS) in Korea for his regulatory purpose 

including the independent regulatory auditing calculation of the major design basis accidents 

during the licensing review and/or the safety evaluation on the operational transients and 

incidents experienced. 

AF-Cl. as a main designer of the CANDU plants, also developed a best estimate code 121 for 

the system safety analysis and the code has been applied to the preparation ol the safety analysis 

report of Wolsung Units 2, 3 and 4. Although the code was developed based on two-fluid 

equations and the various unique features of CANDIU type reactor were included in the code, 

the code also had a lot of vendor-oriented models and correlations which were, in nature, 

conservative or not in their use. Therefore, the code may be improper to use for regulatory 

purpose. 

As one of the code used in the regulatory analysis, the RI-LAP5 code 131 has been extensively 

applied to the Pressurized Water Reactors (PWR) safety analysis for a long while in KINS since 

the late 1980's. The code was introduced from the United States Nuclear Regulatory 

Commission (tJSNRC) through the International Code Assessments and Applications Program 

(ICAP) and the Code Applications and Maintenance Program (CAMP). Now the RELAP5 code 

is one of' the world-wide well known code by the international cooperation on the code 

veriticationi and improvement. It is, therefore, efficient for the KINS staff to develop the 

RIll .A P5-based code for the CAN DlIJ-type reactor analysis. 

It seems to be successful in sonic audit calculations, since RHEAP5 code has its own heavy 

%%,ater steam table and essential Ieatures Ior two phase characteristics. Whether it was successful 

or not, it also seems that some charactcristits are much dependent to the ('ANI)UJ system 

componcnt which was not considered specifically in R .A P5. Those features can be one of the 

motiVlatio of the development of the CAN )IU specific models and further a RHI.AP5/('AND)U 

code.
I his study is focused to develop a thcrmal hydraulic auditing code lbr CAN [)[-type plant by 

extending the model of the current RlI,A P5/M()l)3. In this study, the result from tie previous 

study was used as a basis for code improvement, i.e., the identified major thermal hydraulic 

phenomena for the key CANDU events and the identified modeling limitation of' current 

RI'LAP5/MOI)3 f1r CANDU applications 14, 51. Improvements and verifications of the 

important models idcntified are described in this report. 

The Chapter 2 of this report sutmmarized the model improvement area derived firom the 

previous study. The included models are reactor kinetics decay heat model, Moody critical flow 

model, horizontal flow regime model, horizontal fluel bundle heat transf'er model, digital control 

component model, motor operated valve model, and pressurizer spray model. The basis, 

implementation method, and functional verification of each model are described in the Chapter 

3. The summary and conclusions from the present study are discussed in ('hapter 4. lhe 

modilied part of' the Appendix A "Input Requirements" of' the REIAP5 Manual Volume 2, 

which provides the inlformation required to activate the new CANI)U models, is listed in the 

Appendix A of' this report. The Appendix B lists the RtIAP5 inputs used in the developmental 

verification. The modified source code was submitted to IJSNRC in May 2000 and expected to 

be available for the CAMP members to use.
2. Identification of Model Improvement Area

The major phenomena identifications for the important design basis accidents in CANDU plant 

were tried to find out the model improvement area in the REIAP5 code. l'he RE-AP5 

modeling capabilities for each phenomena of a specific accident scenario were evaluated by the 

expert panels. These procedures follow the well-known PIRT (phenomena identification and 

Ranking) process of the CSAU (Code Scaling and Uncertainty) method 141. The identified 

weaknesses of RELAP5 model for CANDU were prioritized by an expert group in considering 

of its significance and implementation difficulties [51. The resultant area of model improvement 

was shown in Table I.

Table 1. Model Improvement Area in RELAP5/MOD3.2.2 identified for CANDU plant 

application

Relevant Model

I.Flow Regime 

2. I eat Transfer 

3.1)ecay Model 

4.Critical Flow Model 

5.Critical Ileat Flux 

6. Control Model 

7. Special Component 

Model

Model Improvement Area

Improvement of ttorizontal Flow Regime in CANDI! Fuel 

Channel 

Fuel Flement I leatup when horizontal stratification occurs 

ANS94-4 Model Implementation 

Moody Two Phase Critical Flow Model 

D,O 37 bundle CIIF Lookup Table Implementation 

Digilal Samnpling Time Model 

7. I I leader Model ( Reactor Inlet, Outlet I leader) 

7.2 Improvement of Motor Operated Valve 

7.3 Degasser Condenser Spray Model

Accident

LIOCA

L.OCA 

General 

General 

General 

Non I.OCA 

LOCA 

General 

Non I.OCA
3. Model Extensions and Improvements

3.1 Improvement of Reactor Kinetics Model 

Model Implementatjon 

The natural uraniumn fuel is used in CANDU reactor core and significant amount of fissile 

Plutonium is produced from neutron capture in tjj2

, during the burnup. Since the decay heat is 

determined from tlie fission fragment of fission material, the Pu contribution on dacay heat is 

more important to the natural uranium core than the enriched uranium core. Although user 

option has been provided in RELAiP5 of using the ANS73-1, ANS79-1 and ANS79-3 model for 

decay heat model, there is another ANS standard decay model, ANS94-4 f6j, which can 

describe one more isotope, Pu 2

'11 behavior.

Table 2. Comparison of Decay Ileat Models proposed by ANS 

D. Oiptiqn ANS7, A)NS73-I ANS79-3 ANS94-4 

Isotope Uranium U-2359 Pi -9Q !/-235, Pu-239, Pu-24 I,

Experimental D)ata 

Base 

Decay Group of 

Fisson Products 

Treatment of 

Uncertainty 

Valid Shutdown 

Time

K.Shure (1961) 

II 

LO< 10' 20% -40% 

1 03<t< 107 10% -20% 

I 10' 125% -50%' 

109 sec( 30 yrs)

ENDF/B-IV, 

Gunst,Conner,Conway,S 

pinrad, Unik, Findler, 

Johnston, Lott, Fries & 

Others (1971 1978) 

23 flor each isotope 

One standard deviation is 

tabulated for each isotope

I > 109 sec ( 30 yrs)

UJ-238 

I)icken, Bauming, 

Akiyama, Johasson, 

Tobias, England & 

Others (1981 --1989) 

23 for each isotope 

One standard deviation 

is tabulated for each 

isotope. 

t • I0' sec( 300 yrs)

4
Table 2 shows a comparison of the various decay heat models proposed by American Nuclear 

Society. As shown in table 2, the ANS 1979-3 model uses 3 isotopes (2 U1IU,U. 'gPu) and 23 

decay group for each isotope. For the CANDU application as mentioned above, the proposed 

ANS94-4 model which contains the Pu2'1 contribution was added as RELAP5 decay heat model. 

For the usage of ANS94-4 model, user must specify 'ANS94-4' in the fission product type of 

the RELAP5 input which enable to activate the power fraction of Pu24 1 and power history of 

Pu-2'. Appendix A describes more about the modified part of RELAP5 manual. 

Verification of Model Installation 

The model installation verifications are performed using a conceptual problem on single pipe 

with kinetic power source. As a initial condition, the followings are assumed for each decay 

heat model. 

I) In ANS79-3 model , the power fraction of U235/U 23 8

/pn,23 9 is assumed as 0.5/ 0.05/ 0.45, 

whereas in ANS94-4 model, the power fraction of U235

/U23•/pu 239

/pu 24

1 is assumed as 0.5/ 

0.05/ 0.40/ 0.05. 

2) The power fraction of Pu (0.45) was allocated to each Pu isotope in using ANS94-4 model. 

Figure I and 2 show the short term trends of total power and decay heat after a reactor trip. The 

decay time constant of Pu 241 is higher than Pu239, and the decay power using ANS94-4 model is 

lower than power of ANS79-3 model as expected. From this comparison, it was found that the 

ANS94-4 decay heat model was successfully implemented into the RELAP5 code.
3.2 Implementation of Moody Critical Flow Model

Model Implementation 

In reactor blowdown transients, choked or critical flow will exist at the locale of the break. A 

one-dimensional choked flow model developed by Ransom and Trapp was employed in 

RELAP5/MOD3 as a default model. The tHenry-Fauske subcooled critical flow was also 

adopted as an optional use of RELAP5. The I-1-F critical model becomes a default model from 

RELAP5/MOD3.2.2 gamma version. Although the Henry-Fauske model requires a non

equilibrium factor and can be adjusted by user's input, the conventional Moody model for two 

phase flow is needed for evaluation of the conservative tipper limit of discharged flow. This 

feature would be required by the regulatory position of evaluation of radiological amount 

through the spillage of primary system. For the application of PWR and P1-WR both reactor 

types, the implementation of Moody model was started from his original equations 17,81. 

(;21It 2(h,-h,, -Xh~g) 1 112 I)X. + I 

Where 

Q, Critical Mass Flux, 

h,= stagnation enthalpy 

X. =Exit equilibrium quality 

v specific volume 

Hl - velocity ratio (v,/vr) 

Moody assumed the pressure and velocity ratio as independent variables, and derived the 

following equation for the condition of maximum critical flux at exit throat location. 

(l /(2) 

Wecan(l/ e tflisic io a (3) 

We can derived the following slip condition by applying condition (2) using equation ( 1). 

1t ('/'t•)":(4)

7
Substituting equation (4) in equation (I), we can derive the single equation which can be 

represented as a function of exit property. For a given stagnation enthalpy and pressure, the 

throat pressure can be determined by numerically while maximizing the equation (I). The 

bisection method was used for the stable searching of the maximum condition. 

I-or the transition from subcooled critical flow model, i.e. I lenry-Fauske model, thie following 

restriction was added in the application of Moody model 

If x,, - 0.1 Use Moody Model 

x,, < 0.!1 Use I lenry-Fauske Model 

Where xO means the stagnation enthalpy of upstream condition 

The smoothing function between II-F model and Moody model was not applied yet in this stage. 

The Moody model can be activated through the optional use in Group I card in REIAIP5. The 

modified part of input manuals are presented in Group I card of the Appendix A. 

Verification of Model Installation 

For the model installation verifications, two Marviken critical flow experimentl9l, tests 15 and 

24 were calculated by default model, I lenry-Fauske model, and Moody model. Flhe RFLAP5 

input for the Marviken test assessment was listed in Appendix B. Figures 3 and 4 show 

comparisons of break flow for each test. T'he calculation results using Moody model were 

compared with the I lenry-Fauske model, Ransom-Traff mechanistic model and experimental 

data. As shown in Figures, the Moody model predicts the flow rate higher than I lenry-Fauske 

model and Ransom-Traff model at the starting of two-phase flow ( -20 seconds after break ) as 

expected. As consequences, the tank is going to be empty faster and thus the tw o phase critical 

flow turns to be a steam flow more earlier. iFrom this comparison, it was I'ouMd that the Mlood) 

crilical flow model was successlfully implemented into the RI IAP5 code.

8
3.3 Improvement of horizontal flow regime model for CANDU Fuel Channel 

Model Implementation 

The horizontal flow regime map in REILAP5 is similar to tile vertical flow regime map except 

that the post-CilF regimes are not included, and a horizontally stratified regime replaces the 

vertically stratified regime. The horizontal flow regime map therefore consists of horizontally 

stratified, bubbly, slug, annular mist, and mist-pre-CliF regimes. The criteria lor the bubbly-to

slug and the slug to annular mist regimes are also similar to those for the vertical map. The 

criterion defining the horizontally stratified regime is based oil the one developed by Taitel and 

Dukler 1101. According to Taitel and Dukler, the flow field is horizontally stratified if the vapor 

velocity satisfies the condition Jvj < v ,,, where v ,,, is the gas velocity above which waves oil 

the horizontal interface will begin the grow and is given by following Equation. 

v,,,l = I [(P - 7,• )ga I- coso) (5) 

2L P, Sill j 

The equation was derived tor the case of circular pipe, and the direct application for CAN[)IJ 

fuel bundle channel containing 37 fuel elements should be improper in its geometrical features 

and thermal hydraulic features., Moreover since tile REI.AP5 uses the hydraulic equivalent 

diameter which is much smnaller than CANDIJ channel diameter in the calculation of Vc,,,, the 

horizontal stratification occurs more hardly than the expectation in channel. 

For the application in the ('ANDU ftuel channel , the following critical velocity criteria proposed 

by I lanna (1984) in CATI II¢NA codel I l I was considered. 

.... 9 ,p hz, P (6) 

a. 

s. a,f (7) 

F ol-", +(l aa , P' . =z a I / + ( I -- az),:

I0
where y, = height of water-steam interface 

Al',) = channel width at height y 

k = identification of phase (g or f) 

For the simple geometry such as circular pipe and rectangle, the linear integration value can de 

determined analytically as a function of void fraction. Since it is impossible to derive an analytic 

solution for the CANDU channel in which 37 fuel elements were loaded, the pre-calculated 

table values with respect to void fraction were used in calculation of a critical velocity in Eq. (6) 

through Eq. (7). 

The comparisons of critical velocity obtained from the Hanna model and Teitel Dukler model 

are presented in Figure 5 and 6 for low pressure and high pressure, respectively. As shown in 

figures, the stratification vapor velocity of Hlanna model is much higher than Taitel & Dukler 

model. The channel diameter effect was also considered in comparisons. Instead of using a 

hydraulic diameter (0.75 cm) for equation (5), which is a default for RELAPS, the CANDU 

channel diameter (10.34 cm) was tried for Taitel & Dukler model. It is also shown that Hlanna 

model give a higher stratification velocity at low void fraction, where fuel elements are 

submerged into the water. 

In addition, the liquid superficial velocity effect on stratification flow is considered through the 

experimental observations of MR2 data 112]. According to the experimental finding, a 

restrictive condition was added such that the transition from the horizontal stratified flow to the 

fully mixed flow occurs in the range of liquid superficial velocity of 0.085 - 10 m/s. 

In order to activate the above model, a special new component, namely 'CANCHAN' 

component is introduced in new features of RELAP input. The modified parts of component 

input are presented in the part of component input of Appendix A. 

Verification of Model Installation 

[ihe horizontal stratified flow regime model was validated from the sample calculation for a 

simple concepwual problem. A simple pipe model, presented in Figure 7, represent the single 

fuel channel of typical CANDU core. The channel was filled initially with saturated water. As a 

boundary condition, the saturated water and steam were introduced into the channel at the 

various superficial velocities;j/ andjA. The RELAP5 input for the conceptual problem was listed

II
in Appendix B. The steady state is sustained after an initial transient and flow regimes are 

determined for each.j/ Jg boundary condition. 

Figures 8 and 9 show the predicted flow regime using a TCANCI IAN' component model and a 

'PIPE' component model, respectively. As shown in comparisons of two figures, the horizontal 

stratification range in CANDU channel (CANCIIAN) component becomes much broader than 

in equivalent PIPE component. This trend is expected from the model change of stratification 

criteria and consistent to the experimental observation as shown in Figure 10. From this 

comparison, it was found that the new horizontal stratified flow regime criteria was successfully 

implemented into the RELAP5 code.

12
3.4 Implementation of CANDU 37 Fuel Bundle Heat Transfer Model 

Model Implementation 

An important factor that affects the magnitude of heat transfer coefficients, besides obvious 

parameters such as velocity, is the flow field or hydraulic geometry surrounding the heat 

transfer surface. Although RELAP5 has various boundary geometry type options to help users 

communicate the flow field geometry types to the code and some number has been assigned for 

some of the possible geometry, the specific coding for the assigned geometry was not available 

yet in the current RELAP5 code. 

The CANDU reactor core has horizontal fuel rods in horizontal pipes. It was also assigned as a 

number '124' for its boundary type, no specific coding has been implemented. After reviewing 

the heat transfer correlation for the case of 121-133 boundary option, we conclude that most 

correlation of horizontal heat transfer package in RETAP5 could be applicable generally for the 

CANDU reactor channel if an appropriate critical heat flux correlation would be used. 

Exception of this general validity of heat transfer package is one for the fuel element when the 

horizontal stratification occurs in CANDU fuel channel. Since each of 37 fuel elements in the 

channel has a different spatial location, such an effect should be considered in heat transfer 

calculation when horizontal stratification occurs. The following modifications of the CItF 

model and the heat transfer effect of horizontal stratification were attempted in the present study. 

CtlF Model 

RIELAI5 uses AECL CI IF lookup tables based on tube data, and a special mu1ltiplication factor 

for horizontal geometry, namely horizontal flow multiplier, k6, is applied in critical heat flux 

calculation. The factor is determined by the degree of stratification based on the channel void 

fraction only. 

Figure 5 shows the comparisons of RFIAAP5 CIIF tube data and AECIL 37 bundlIc •'lIH data, 

and the ('IIF tube data base and horizontal 11ow innIthiplier coUld not be applicable to (ANDI) 

core. Therefore we add one subroutine which can calculate CIIF using AlCI 1),() 37 bundle 

data iI user selects the number 124 as ('ANI)1. core boundary type in the heat structure 

modeling. The modified part of input fieatures -,.as presented in the Appendix A. In this input 

ifature, the following three factors concerning grid spacer effect, heated length ellcct. and axial

16
flux profile among the eight factors can be used as multipliers for AECL 1)20 37 bundle CHF 

table and other 5 factors are fixed as a constant value, i.e. 1.0. However, the AECL D20 37 

bundle CHF data was classified as a AECL proprietary information, the distributed subroutine 

was coded such that the data was actually not used when specifying the number '124' in tile 

heat structure input. 

"* k1 : Hydraulic Diameter Effect = 1.0 

"* k2 : Bundle Effect = 1.0 

"* k3 Grid Spacer Effect : User input 

"* k4 : Heated Length Effect : User Input 

"* k5 : Axial Flux Profile : User Input 

* k6 : Horizontal Flow Factor = 1.0 

"* k7 = .0 

"* k,: Non aqueous factor = 1.0 

Horizontal Stratified I-eat Transfer Model 

When a horizontal stratification occurs in CANDU fuel channel, there should be a significant 

difference of local conditions through the elevation in a channel, such as void fraction, velocity, 

and sometimes pressure. Most important parameter for heat transfer would be local quality (or 

void fraction) and velocity. If we assume the complete separation, the water level can be 

calculated from the void fraction even though it is not a simple analytical formula in CANDU 

channel. Separated conditions for each phase are also calculated in the two fluid model. For the 

given elevation of each fuiel element in channel, the local conditions of fuel element can be set 

as follows; 

If Z,,,,, t,,,(, > Z,,,. : a,, 1.0, x = 1.0, and V,,,, = Vg 

If Z,f,,,,,,,,ifei > Z,,aur. : ag 0. 0, x = 0.0, and V,,, =V 

If Z.h,,,,l,,f,,l,,, < Z,,,,.,, < 4.1, ,,, 1 : Properties are interpolated from height basis 

Where Z,,op is a top elevation for a given fuel element in a horizontal channel and Z. I,..,,,, is a 

bottom elevation for a same element. Z ,ij,,,r is an elevation of the two phase mixture in channel. 

The logic diagram of heat transfer model is given in Figure 12 and schematic diagralm of fuel 

element in CANDU channel is given in Figure 13. The modified input feature enables the users 

to put the elevations of each fuel element in a CAN DU channel. The modified parts of the heat 

structure input are presented in the Appendix A.

17
Verification of Model Installation

The model of 37 Bundle CI IF would be validated by CtIF data itself. The horizontal stratified 

heat transfer model was validated from the sample calculation for a simple channel conceptual 

problem. Figure 14 represents the single fuel channel of typical CANDIU reactor core. The 

channel was filled initially with saturated water in 10.69 MPa. As a boundary condition, the 

saturated water was flow into the channel at the low speed, 0.1 m/sec. Each element of 37 fuel 

has a constant power 200 kw/fuel rod. The total fuel rods were modeled as two groups of upper 

elements and lower elements. The RELAP5 input for the channel problem was listed in 

Appendix B. 

As progressing of transient with the heating of fuel, the void is filled in the channel and the 

horizontal stratification occurs. Using the present stratified heat transfer model, the upper fuel 

group should be heated if the mixture level falls down below the tipper element. Figures 15 and 

16 show comparisons of the heat transfer coefficients and the sheath (cladding) temperatures 

between default model and the new heatup model, respectively. As shown in Figure 15, the 

upper fuel group has lower heat transfer coefficients than that of lower group fuel. The tipper 

group fuel experienced the single phase steam cooling, otherwise film boiling occurs in tile 

lower group fuel. Consequently the heatup has been experienced in the upper part of fuel. 

Figure 16 shows the temperature of CADU fuel sheath. Without the stratified heat transfer 

model, the sheath temperature is between the trends of upper and lower group fuels. From this 

comparison, it was found that the new heatup model was successfully implemented into tile 

RELAP5 code.

18
3.5 Implementation of Digital Sampling Model in Control Function 

Model Implementation 

The control system function of RELAP5 provides the capability to evaluate simultaneous 

algebraic and ordinary differential equations. The capability is primarily intended to simulate 

control systems typically used in hydrodynamic systems, but it can also model other phenomena 

described by algebraic and ordinary differential equations. Although the various control 

functions have been provided in RELAP5, it has some shortcomings for the simulation of the 

digital control system. Digital devices are widely used in the major part of CANDU plant, and 

the signals from devices are processed and controlled by digital logic. One of major differences 

between analog process and digital process is the procedure for digital sampling process. The 

digital signal are not detected on line simultaneously, but sampled in a sequential order. This 

sampling time is considered in newly designed control function, 'DIGITAL'. The DIGITAL 

control function require the user inputs for the sampling time, delay time. Appendix A provides 

the more details about user inputs required for D)IGITAL component. 

Verification of Model Installation 

The blowdown problem in Edward pipe was used for the verification of DIGITAL. control 

function. The RELAP5 input was listed in the Appendix B. The I)IGITAL function was applied 

for processing the pressure at the volune 301 in each sampling rate of 0.05 seconds and 0.1 

seconds. Figure 17 shows a comparison of the calculated pressure and the digitally processed 

one. As shown in the Figure 17, the digitally processed result shows stepwise changes in 

pressure, which remains constants during the specified sampling times. From this comparison, it 

was found that the digital sampling model was successfully implemented into the REIAP5 code.

23
3.6 Improvement of Motor Operated Valve Model

Model Implementation 

The RELAP5 has a special process model for motor operated valve (MOV). This valve model 

has the capability of controlling the junction flow area between two control volumes as a 

function of time. The operation of the valve is controlled by two trips; the first one for opening 

the valve and the second one for closing the valve. A constant rate should be specified to control 

the speed at which valve area changes in the existing RELAP5 calculation. Sometimes the 

motor operated valve (MOV) is used for relief valve modeling for the sake of simplicity, even 

though RELAP5 has a detailed mechanistic relief valve model. The liquid relief valves of the 

typical CANDU plant have important roles of pressure regulation and have been frequently 

modeled as MOV that were controlled by the set points. The difficulties in modeling of relief 

valve as MOV come from the relief valve characteristics, which have different rates for opening 

and closure. For the more Ilexible application of the MOV model, the extra input for closure 

rate was designed and modeled in a CANDU version. Appendix A shows the modified part of 

manual for MOV input. 

Installation Verification 

A sample problem was calculated using different changing rates of MOV. The RELAP5 input 

for the problem was listed in Appendix B. Figure 18 shows the valve stem position calculated 

with new model. As desired, the MOV was opened at the open rate input value by opening trip 

signal and closed at the closure rate by closure trip signal. From this result, it was found that the 

new MOV model was successfully implemented into the RELAP5 code.

25
3.7 Implementation of Pressurizer Spray Model

Model Implementation 

Usaually, the pressurizer could be modeled as a pipe component with several volumes in 

RELAP5 calculation. Since RELAP5 does not have a special model for pressurizer, the spray 

droplet sizes were determined by the flowing condition, and independent of geometry of 

spraying nozzles. The sprayed droplets would be almost saturated condition before arriving at 

water surface of PWR pressurizer component. In such condition, total heat transfer taken out 

from steam is not sensitive to sprayed droplet sizes. Since pressure depression by spray is 

governed mainly by the droplet-steam heat transfer, spray droplet size is not important in the 

various transients. 

In the typical CANDU plant, a "degasser-condenser" component has a similar function of PWR 

pressurizer. However the spray water for the degasser component comes from the D20 storage 

tank, in which highly subcooled heavy water is stored. The non-condensable gas may exist in a 

degasser-condensor. In such an environment, the sprayed water would not be saturated 

condition completely during falling down. Therefore, the spray droplet size becomes much more 

important in CANDU degasser-condenser than PWR pressurizer. 

1he new component named "PRIZER" is designed such that user can input the spray droplet 

size and the interfacial heat transfers. As a default model, the interfacial heat transfer coefficient 

and droplet sizes are determined as the same as RELAP5 accumulator model. The calculation 

model for the determination of mixture level in PRIZER component is added also for user 

conveniences. Appendix A shows the more detailed input scheme in PRIZER. 

Installation Verification 

A sample conceptual problem was calculated to confirm if the effect of the droplet size was 

predicted using the PRIZER component model. The RELIAP5 input for the problem was listed 

in the Appendix B. Figures 19 and 20 show the calculated temperature distribution and pressure 

drop for the various droplet sizes. As shown in figures, the temperature increase of subcooled 

droplet is affected by droplet size and pressure drop in P'RIZER component is increased by the

27
decreasing of droplet size. From this result, it was found that the PRIZER model was 

successfully implemented into the REIAP5 code.

28
4. Summary and Conclusions

The improvement of some thermal-hydraulic models in the current RE[AP5/MOD3 was 

made for the purpose of CANDU type PItWR application. In this study, the major thermal 

hydraulic phenomena for the key CANDU events and the modeling limitation of current 

REI.AP5/MOD3 for CANDU applications obtained from the previous study were used as a 

basis for model improvement. The code improvement was made such that the new CANI)U

related capability can be used by the selection of user option while maintaining tile current 

REI.AP5 PWR analysis capability 

The seven items were improved not only for CANDU reactor but also for generic nuclear 

reactor system. The CANDU fuel channel heat transfer model and the flow regime model were 

improved to be suitable to a CANDU specific feature. The stratification criteria proper to 

CANDU fuel feature and the fuel element heatup process induced by stratification were newly 

implemented. The digital control model was mainly deduced from CANDIM plant specific 

feature of digital control, but it could be also applied to the special processing feature of plants. 

By this improvement, the digitally processed signal can be simulated. Other four items, i.e. 

ANS94-4 decay heat model, Moody critical model, motor operative valve model and pressurizer 

spray model, were developed on generic base and could be applicable to PWR also. Especially, 

the plutonium contribution to decay heat can be considered by the ANS94-4 decay heat model. 

The Moody critical flow model using a heavy water property can provide an additional 

capability to evaluate the conservative break flow in CANDU system. Simulation of different 

rate of opening and closing the motor valve is now possible when calculating tile liquid relief 

vale behavior during transient. And the new pressurizer spray model can be used for evaluating 

the droplet size effect on the condensation. All of those improvement were verified through 

some assessments with simple conceptual problems and Marviken critical flow test. 

By applying those models in the RELAP5/MOD3.2.2 gamma version code. 

RELAP5/MOD3/CANDU version has been established [13,14]. For the sake of developer's 

convenience, new version was rewritten and developed by FORTRAN90 language. The 

developed CANDU version could be used for more realistic estimations of thermal hydraulic 

behavior in CANDU channel during a LOCA. 

Although the functional ability of RI-,IAP5/MOI)3/CANDU version for the plant analysis 

was confirmed through the verifications, the model specific assessments were not perlormed yet. 

The flow regime and heat transfer model in CANI)U channel should be assessed and confirmed 

further through the comparison with experimental data. There must be more assessments for

30
pressurizer spray model also. One of the important CANDU specific model would be ROtl/RIH 

(Reactor Outlet Header/ Reactor Inlet Header Model) component model. Although the 

ROH/RIH model was not implemented to CANDU version yet, the model should be developed 

in the near future.

31
References

[11 "CANDU System Training Course", Presented at KAFRI/NTC, Feb. 22 - Mar.5 (1993) 

[2] B.N. Hanna " CATHENA MOD-3.5/Rev 0; Theoretical Manual" RC-982-3, COG-93

140 Rev 0.0, AECL, Whiteshell Lab.(1995) 

[31 Thermal Hydraulics Group "RELAP5/MOD3 Code Manual Volume I : Code Structure, 

System Models, and Solution Methods", Scientech, Inc., NUREG/CR-5535 (1998) 

[41 Shaw, R.A., Rouhani, S.Z., Larson, T.K., Dimenna, R.A., "Development of a Phenomena 

Identification and Ranking Table (PIRT) for thermal-hydraulic phenomena during a PWR 

(pressurized water reactor) large-break LOCA (loss-of-coolant accident)", NI JR EG/CR

5074; EGG-2527, November (1988) 

151 B.D.Chung, W.J.Lee, Il.S.Lim, "Development of Best Estimate Auditing Code For 

CANDU Thermal Hydraulic Safety Analysis", KINS/IlR-200, KAERI/CR-48/98 (1998) 

[6) "American National Standard for Decay I leat Power in Light Water Reactors", 

ANSI/ANS-5.1-1994, American Nuclear Society, approved by American National 

Standard Institute, Inc. (1994) 

[71 F.J. Moody, "Maximum Flow Rate of a Single-Component, Two-Phase Mixture". Trans. 

ASME, J. of Heat Transfer, pp 134-142 Feb. (1965) 

[81 J.Il.McFadden et. al, "RETRAN-03 : A Program for Transient Thermal-Hydraulic 

Analysis of Complex Fluid Flow Systems, Volume 1 : Theory and Numerics", NP-7450, 

EPRI, page IV-13, May (1992) 

[91 Studsvik Energieknik AB, "The Marviken Full-Scale Critical-Flow Tests", F. PRI/NP-2370, 

Final Report, December ( 1982) 

1101 Thermal Hydraulics Group "RELAP5/MOD3 Code Manual Volume 4 : Models and 

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

[Il B.N. lHanna "CATHENA MOD-3.5/Rev 0; Theoretical Manual", page 3-5, RC-982-3, 

COG-93-140 Rev 0.0, AECL, Whiteshell Lab.(1995) 

1121 A.M.M.Aly, "Flow Regime Boundaries for an Interior Subchannel of a Hlorizontal 37

Element Bundle", The Canadian Journal of Chemical Engineering, Vol. 59, pp. 158, April 

(1981) 

[131 B.D.Chung, W.J.Lee, t!.S.Lim, "Development of Best Estimate Auditing Code for 

CANID)IU Thermal Hlydraulic Safety Analysis". KINS/IIR-248, KAERI/CR-67/99 (1999) 

1141 B.I).Chung, W.J.Lee, I I.S.Lim, "Development of Best Estimate Auditing Code for 

CANDI IThermal Hlydraulic Safety Analysis", KINS/I IR-293, KAERI/CR-89/2000 (2000)

32
Appendix A 

Input Manual Change for RELAP5/MOD3/CANDU

33
A2.1 Card 1, Developmental Model Control

This card has been added to the code for the convenience of developers in testing model 

improvements or new models. This card is not a standard input feature of the code. The 

description of this card has been added to the input requirements because several laboratories 

are receiving test versions to assist in the development and testing of the code. Anyone using 

this card must realize that they are selecting experimental options still under development. 

Furthermore, these options may change more frequently than the revision of this input manual. 

Thus, before using the options, users should obtain the brief listing of current opt ions from the 

code (described below)and verify those descriptions against this manual. 

The purpose of this card is to allow developers and analysts to quickly test new models by 

activating or deactivating a model through simple input instead of program modification, 

compilation, and loading. Ninety logical variables having only false or true values are provided 

and defined at the start of program 

Option 48 user request the use of level model when vargrav flag is turned on. 

Option 51 turns off water packing in all volumes. 

Option 52 turns off choking at all junctions. 

Option 53 invokes the modified I lenry-Fauske critical flow model. 

Option 54 invokes the Moody Critical Flow Model for Two Phase 

Option 56 enforces vg. v1 at alpha =1 in fidis2.F. 

Option 60 The changes that this option enabled are now part of the code. 

Option 62 uses newly developed changes to Chen f factor in prednb. 

CARDS 301 THIROUGH 399, MINOR EDIT DATA REQUESTS 

These cards are optional for NEW and RESTART problems, are required for a RFIFl)fI 

problem, and are not allowed for PLOT and STRIP problems. If these cards are not present, no 

minor edits are printed. If 

A4.2 Component Quantities 

The quantities listed below are unique to certain components- for example, a pump velocity can 

only be requested for a pump component. The parameter is the component number, i.e., the 

three-digit number ccc used in the input cards. 

Code Quantity 

AC'PGTG Accumulator vapor specific heat, Cp. at vapor temperature (J/kg K. Btu/lb [F).

34
ACPNIT 

Btu/Ib 'F). 

ACQTANK 

(W, Btu/s) 

ACRHON 

ACTTANK 

ACVDM 

ACVGTG 

ACVLiQ 

AHFGTF 

AHFGTG 

AHFTG 

AlIHGTF 

AVGTG 

AVISCN 

BETAV

Accumulator noncondensable specific heat, CP, at vapor temperature (J/kg K, 

Total energy transport to the gas by heat and mass transfer in the accumulator 

Accumulator noncondensable density (kg/rn 3 , Ib/f3 ). 

Mean accumulator tank wall metal temperature (K, 'F). 

Gas volume in the accumulator tank, standpipe, and surge line (i 3

, fi3 ). 

Accumulator vapor specific heat, C, at vapor temperature (J/kg K, Btu/Ib 'F). Liquid volume in the accumulator tank, standipipe, and surge line (in3

, fW3 ). 

Accumulator heat of vaporization at liquid temperature (J/kg, Btu/lb). 

Accumulator heat of vaporization at vapor temperature (J/kg, Btu/lb). 

Accumulator liquid enthalpy at vapor temperature (i/kg, Btu/lb). 

Accumulator vapor enthalpy at liquid temperature (J/ki, Btu/lb). 

Accumulator specific volume at vapor temperature (m /kg, ft lib). 

Accumulator noncondensable viscosity (kg/m.s, lb/ft s). 

Accumulator steam saturation coefficient of expansion (K- 0 F- 1.

CDIM GE mechanistic dryer critical inlet moisture quality. 

DIM GE mechanistic dryer inlet moisture quality. 

DMGDT Accumulator/time rate of change in dome vapor mass (kg/s, Ib/s). 

GDRY GE mechanistic separator capacity factor. 

OMEGA Inertial valve disk angular velocity (rad/s, rev/min). 

PMPIIEAD Pump head in the pump component (Pa, lbl? in2 ). 

PMPMT Pump motor torque (N m, lbf ft). 

PMPNRT Calculated pump inertia (kg in2 , lb ft). 

PMPTRQ Pump torque in the pump component (N in, lbf ft). 

PMPVEI. Pump velocity in the pump component (rad/s, rev/min). 

PRZI.VL Pressurizer level in the PRIZER component (in, ft) 

TI IE'TA Inertial valve disk angular position (deg). 

TUREFF The efficiency of the turbine component. 

TURPOW The power developed in the turbine component (W, Btu/s). 

TURTRQ The torque developed in the turbine component (N m, lb ft). 

TURVEL The rotational velocity of the turbine component (rad/s, rev/min). 

VLVAREA This is the ratio of the current valve physical area to the junction area. The 

junction area is the fully open valve physical area for the smooth area option and the minimum 

of the two connecting volumes for the abrupt area change. 

VLVSTEM This is the ratio of the current valve stem position to the fully open valve stem 

position for the motor and servo valves when the normalized stein position option is used. For 

the motor and servo valves when the normalized area option is used and for all the other valves, 

this is the ratio of the current valve physical area to the fully open valve physical area. 

XCO GE mechanistic separator liquid carryover quality. 

XCU GE mechanistic separator vapor carryunder quality. 

Xl GE mechanistic separator inlet quality.

I

A7.6 Pipe, Annulus Component

A pipe component is indicated by PIPE, an annulus component is indicated by ANNULUS, and 

a pressurizer component is indicated by PRIZER , and a CANDU Channel component is 

indicated by CANCI IAN on Card ccc0000. The PIPE and ANNULUS components are similar, 

except that the ANNULUS component must be vertical and all the water is in ihe film (i.e., no I

35
drops) when in the annular-mist flow regime. The remaining input for both components is 

identical. More than one junction may be connected to the inlet or outlet. If an end has no 

junctions, that end is considered a closed end. For major edits, minor edits, and plot variables, 

the volumes in the pipe component are numbered as cccnn0000, where nn is the volume number 

(greater than 00 and less than 100). The junctions in the pipe component are numbered as 

cccmm0000, where mm is the junction number (greater than 00 and less than 

A7.6.1 Card cccOOO1, Pipe, Annulus, Prizer, CanChan Information Card 

This card is required for pipe components. 

WI(I) Number of volumes, nv. nv must be greater than zero and less than 100. The number of 

associated junctions internal to the pipe is nv-I. The outer junctions are described by other 

components. 

W2(I) Surgeline Connection Number. This word must the same format as printed in the 

output. The input is required for the PRIZER component and must not be entered for PIPE and 

ANNULUS component. 

W3(R) User specified interfacial heat transfer coefficient from liquid to saturation state (W/In2

K, Btu/hr-ft2-F). This word is optional for a PRIZER component and must not be entered for 

PIPE and ANNUL[US components. 

W4(R) User specified interfacial heat transfer coefficient from vapor to saturation state (W/m 2

K, Btu/hr-ft2-F). This word is optional for a PRIZER component and must not be entered for 

PIPE and ANNUIAS components. 

A7.6.2 Cards ccc0101 through cccO199, Pipe, Annulus X-Coordinate Volume Flow Areas 

The format is two words per set in sequential expansion format for nv sets. These cards are 

required, and the card numbers need not be consecutive. The words for one set are 

A7.8 Valve Junction Component 

A valve junction component is indicated by VALVIE on Card ccc0000. For major edits, minor 

edits, and plot variables, the junction in the valve junction component is numbered cccOO0000. 

A7.8.1 Cards cccOlO1 through cccO109, Valve Junction Geometry Cards 

This card (or cards) is required for valve junction components. 

A7.8.6.4 Motor Valve. 

This behaves realistically in that the valve area varies as a function of time by either of two 

models specified by the user. The user must also select the model for valve hydrodynamic losses 

by specifying either the smooth or the abrupt area change model. If the smooth area change 

model is selected, a table of flow coefficients must also he input as described in Cards ccc04O(

36
through ccc0499, CSUBV Table Section A7.8.7. If the abrupt area change model is selected, a 

flow coefficient table cannot be input. 

WI(l) Open trip number. 

W2(I) Close trip number. Both the open and close trip numbers must be valid trips. When both 

trips are false, the valve remains at its current position. When one of the trips is true, the valve 

opens or closes depending on which trip is true. The transient will be terminated if both trips are 

true at the same time. 

W3(R) Valve opening change rate (s-1 ). If Word 5 is not entered, this quantity is the rate of 

change of the normalized valve area as the valve opens or closes. If Word 5 is entered, this 

quantity is the rate of change of the normalized valve stem position. IF Word 6 is entered, this 

quantity is the rate of change of the normalized valve area as the valve opens only. This word 

must be greater than zero. 

W4(R) Initial position. This number is the initial normalized valve area or the initial normalized 

stein position depending on Word W5. This quantity must be between 0.0 and 1.0. 

W5(l) Valve table number. If this word is omitted or input as zero, the valve area is 

determined by the valve change rate and the trips. If this word is input as nonzero, the valve 

stem position is determined by the valve change rate and the trips; and the valve area is 

determined from a general table containing normalized valve area versus normalized stem 

position. Input for general tables is discussed in Cards 202tttnn, General Table Data, Section 

A ll. For this case, the normalized stem position is input as the argument value and the 

normalized valve area is input as the function value 

W6(R) Valve closing change rate (s-1 ). If this Word is not entered, this quantity is same as the 

rate of opening change. 

A8 CARDS ICCCGXNN, HEAT STRUCTURE INPUT 

These cards are used in NEW and RESTART type problems and are required only if heat 

structures are described. The heat structure card numbers are divided into fields, cccgxnn. 

where ccc is a heat structure number. The heat structure numbers need not be consecutive. We 

suggest, but the system does not require, that if heat structures and hydrodynamic volumes are 

related, they be given the same number. 

g is a geometry number. The combination cccg is a heat structure geometry combination 

referenced in the heat structure input data. The g digit is provided to differentiate between 

different types of heat structures (such as fuel pins and core barrel) that might be associated with 

the same hydrodynamic volume. 

x is the card type. 

un is the card number within a card type. 

A8.13 Cards 1cccg50 through 1cccg599, Left Boundary Condition Cards 

These cards arc required. The boundary condition data for the heat structures with this geometry 

arc entered in a slightly modified form of sequential expansion using six quantities per set for

37
the number of heat structures with this geometry (nh sets). The modification deals with Words I 

and 2. 

WI(I) Boundary volume number or general table. This word specifies the hydrodynamic 

volume number (of the form cccnn000f) or general table associated with the left surface of this 

heat structure. These are used to specify the sink temperature. 

If zero, no volume or general table is associated with the left surface of this heat structure, and a 

symmetry or insulated boundary condition is used (i.e., a zero temperature gradient at the 

boundary), or a temperature of zero is used for a surface temperature or a sink temperature in 

boundary conditions. 

A boundary volume number is entered as a positive number. 

If f is 0 or 4, the volume coordinate associated values such as average volume velocity are taken 

from the x coordinate; 

if f is 2 or I, volume coordinate associated values are taken from the y or z axes, respectively. 

These numbers define the flow direction parallel with tube bundles. Any flow in other 

directions is vectorally added to give the cross flow mass flux. Specifying a volume coordinate 

not in use is an input error. 

Iff is 7, tile 3D hydrodynamic vomule is used. Then ccc is a channel number and ni is a mesh 

number 

A general table is entered as a negative number (-1 through -999). 

W2(l) Increment. This word and Word I of this card are treated differently from the standard 

sequential expansion. Word I of the first set applies to the first heat structure of the heat 

structure geometry set. The increment (normally 10000) is added to Word 1, which results in the 

hydraulic cell number associated with heat structure 2; etc. The increment is applied up to the 

limit in Word 6 of a set. Word I of the next set applies to the next heat structure, and increments 

are applied as for the first set. The increment may be zero or nonzero, positive or negative. If 

Word I is zero, this word should be zero. Additional examples are shown in Section 4 of 

Volume V. 

W3(I) Boundary condition type. 

If 0, a symmetry or insulated boundary condition is used (i.e., a zero temperature gradient is 

used at the boundary). The boundary volume must be 0. 

If I or Inn, a convective boundary condition where the heat transfer coefficient obtained from 

Hleat Transfer Package I is used. The sink temperature is the temperature of the boundary 

volume. Word I must specify a boundary volume with this boundary condition type. The 

boundary volume cannot be a time-dependent volume. 

There are several numbers allowed for Word 3 to activate convective boundary conditions for 

nonstandard geometries. A 1, 100, or 101 give the default values. The default convection and 

boiling correlations were derived mainly based on data from internal vertical pipe flow. Other 

possible input values are shown in Table A8.13-I. When modelling a vertical bundle, the rod or 

tube pitch-to-diameter ratio should be input on the 901 card. This has the effect of increasing the 

convective part of heat transfer such that users can input the true hydraulic diameter and get 

reasonable predictions. 

"Table A8.13-1 Card 501 and 601 Word 3 convection boundary type.

38
Word 3 Geometry Type 

1,100,101 Default 

102 Parallel plates (ORNL, ANS reactor; set gap and span on 

ccc3 101 -ccc3199 hydro cards for pipes and ccc0 I1I hydro 

card for single volumes and branches, set b = 2 in volume 

control flag on ccc 1001 -ccc 1099 hydro cards for pipes and 

ccc010 l-ccc0109 hydro cards for single volumes and 

branches). 

106 Vertical annulus (CHF using KNOEBEL correlation for 

KMRR DUPIC Test Loop) 

110 Vertical bundle without crossflow (set P/D on 801/901 card) 

124 CANDU Fuel Bundle Element Heat Transkfer 

130 Flat plate above fluid 

134 Horizontal bundle 

If 1000, the temperature of the boundary volume or the temperature from the general table (as 

specified in Word 1) is used as the left surface temperature. If Word I is zero, the surface 

temperature is set to zero. 

If I xxx , the temperature in general Table xxx is used as the left surface temperature. 

If 2xxx, the heat flux from Table xxx is used as the left boundary condition. 

If 3xxx , a convective boundary condition is used where the heat transfer coefficient as a 

function of time is obtained from general Table xxx. The sink temperature is the temperature of 

the boundary volume or from the table specified in Word I. If Word I is 

A8.17 Cards lcccg801 through Icccg899, Additional Left Boundary Cards 

These cards are required whenever the left boundary communicates energy with the left hand 

fluid volume. The cards are in sequential expansion format, nine words per set, describing nh 

heat structures. Sequential expansion would only be used where tile critical heat flux value was 

not of importance, since the length to all heat structures in the expansion would be the same. 

Words 2-8 are used for the ClIF correlation. 

Nine-word format: 

WI (R) I leat transfer hydraulic diameter (i.e., heated equivalent diameter) (m, ft). This is 4*(flow area)/(hcated perimeter) and is recommended to be greater than or equal to the volume 

hydraulic diameter since (heated perimeter) < (wetted perimeter). Ih is possible to input this 

diameter to be less than the volume hydraulic diameter. If Word I equals 0.0, tile volume 

hydraulic diameter is used. 

W2(R) Hleated length forward (In, 11). Distance is from the heated inlet to the center of this slab. 

This quantity will be used when the liquid volume velocity is positive or zero. This is used to 

get the hydraulic entrance length effect. This is used only for the ClIF correlation. It must be >0. 

To ignore tile length effect, put in a large number (i.e., > 10.0).

39
W3(R) Heated length reverse (m, ft). Distance is from the heated outlet to the center of this slab. 

This quantity will be used when the liquid volume velocity is negative. This is used to get the 

hydraulic entrance length effect. This is used only for the CUlF correlation. It must be >0. to 

ignore the length effect, put in a large number (i.e., > 10.0). 

W4(R) Grid spacer length forward (m, ft). Distance is from the center of this slab to the nearest 

grid or obstruction upstream. This quantity will be used when the liquid volume velocity is 

positive or zero. This is used to get the boundary layer disturbance and atomization effect of a 

grid spacer in rod bundles. This is used only for the CtF correlation. If the grid K loss (Word 6) 

is zero, Word 4 is not used. 

W5(R) Grid spacer length reverse (m, ft). Distance is from the center of the slab to the nearest 

grid or obstruction downstream. This quantity will be used when the liquid volume velocity is 

negative. This is used to get the boundary layer disturbance and atomization affect of a grid 

space in rod bundles. This is used only for the CUF correlation. If the grid K loss (Word 7) is 

zero, Word 5 is not used. 

W6(R) Grid loss coefficient forward. Used for forward flow in rod bundles. This quantity is 

used when the liquid volume velocity is positive or zero. This is used only for Cl IF calculation. 

W7(R) Grid loss coefficient reverse. Used for reverse flow in rod bundles. This quantity is used 

when the liquid volume velocity is negative. This is used only for the CUF correlation. 

W8(R) Local boiling factor. Enter 1.0 if there is no power source in the heat structure or if the 

local equilibrium quality is negative (i.e., liquid is subcooled and void is zero). This is the local 

heat flux/average heat flux from start of boiling. If the power profile is not flat, a steady state 

run may help determine this number. This number must be greater than 0.0. 

W9(I) Ileat structure number. 

Twelve-word format (Word I = I on Card lcccg800). The first eight words of this formnat is 

identical to the nine-word format. 

W9(l) Natural circulation length (in, ft). This should be the height of a hydraulic natural 

convection cell. For a heated vertical plate, this is the total height of the plate. For inside a 

horizontal tube, this should be the inside tube diameter. For tihe outer surface of vertical or 

horizontal bundles, it is suggested to use the heated bundle height in the vertical direction. 

When using the nine word format, this quantity is set to Word 1, the heat transfer hydraulic 

diameter. 

W1O(R) Rod or tube pitch-to-diameter ratio (P/D). The default is 1.1. The 

maximum is 1.6. It is not used unless Word 3 on the 501 card is I10, I1I, 114 or 135. If 

CANDU geometry (124 Option on 501 CARD) was selected, this value is relative height of 

fuel element, and value should be within +/- 1.0. 

WI I(R) Fouling factor. This factor is applied to the heat transfer correlations and may be used to represent fouling or to run sensitivity studies. This quantity must be a positive 

nonzero number. When using the nine-word format, this quantity is set to 1.0. 

W 12(l) Heat structure number. 

Thirteen-word Ibrmnat (Word I = 2 on Card ICCCG800). Set Word I = 0. Words 9, 10. and I I 

of this format are identical to the twelve-word format. 

A12.1 Card 30000000, Reactor Kinetics Type Card 

This card is required.

40
W I(A) Kinetics type. Enter POINT or DELETE. Enter POINT for the point reactor kinetics 

option. Enter DELETE in a restart problem if reactor kinetics is to be deleted. No other data are 

needed if reactor kinetics is being deleted. 

A 12.3 Card 30000002, Fission Product Decay Information 

This card is optionally entered for POINT problems if WI of Card 30000001 contains GAMMA 

or GAMMA-AC. If this card is not entered, the Proposed 1973 ANS Standard fission product 

data are used if default data are used. 

W I (A) Fission product type. Enter ANS73, ANS79-1, or ANS79-3, or ANS94-4 

If default fission product data are used, ANS73 specifies the Proposed 1973 ANS Standard data, 

ANS79-1 specifies the 1979 Standard data for 235 U, and ANS79-3 specifies the 1979 ANS 

Standard data for the three isotopes, 235 U, 238 U, and 239 Np. ANS94-4 specifies the 1994 

ANS Standard data for the four isotopes, 235 U, 238 U, 239 Pu, 241 Pu. ANS79-3 and ANS94

4 also requires that power fractions for each isotope must be entered 

If fission product data are entered, ANS73 and ANS79-1 specify only one isotope and ANS79-3 

specifies three isotopes and also requires that the number of decay heat groups for each isotope 

be entered. 

W2(R) Energy release per fission (MeV/fission). If not entered or zero, the default value of 200 

MeV/fission is used. 

W3-W5(R) If ANS79-3 or ANS94-4 is specified in WI, the fraction of power generated in 

235 U, 238 U, and 239 Pu ,or 24 1 Pu must be entered in these three or four words. The sum of 

the fractions must add to one. 

W6-W8(I) Number of groups per isotope. If ANS79-3 or ANS94-4 is entered in WI and 

default data are not being used, the number of decay groups for 235 U, 238 U, and 239 Pu or 

241 Pu must be entered in these three or four words. The number of groups for each isotope 

must be less than or equal to 50. 

A 12.7 Cards 30000401 through 30000499, Power History Data 

If these cards are not present, initial conditions for fission product and actinide groups are for 

steady- state operation at the power given in W2 of Card 30000001. This is equivalent to 

operation at that power for an infinite time. If these cards are present, the power history 

consisting of power and time duration is used to determine the fission product and actinide 

initial conditions. The power from gamma and actinide decay is assumed to be zero at the 

beginning of the first time duration. Data are entered in three- or six- word sets, one or more sets 

per card. Card numbers need not be consecutive. 

W I(R) Reactor power (W). This quantity is the total reactor power, that is, the sum of fission 

powver and decay power, and must be > 0. If a decay power obtained from the power history 

exceeds this quantity, the fission power is assumed to be zero. 

W2(R) Time duration. Units are as given in next word. This quantity must be greater than or 

equal to 0. 

W3(A) Time duration units. Must be sec. min, hr, day, or wk.

41
W4-W7(R) Power fractions. If ANS79-3 or ANS94-4 is entered in WI of Card 30000002, the I 

power fractions for 235 U, 238 U, and 239 Pu or 241 Pu must be entered in these words. 

A14 CARDS 205CCCNN OR 205CCCCN, CONTROL SYSTEM INPUT DATA 

These cards are used in NEW and RESTART problems if a control system is desired. They are 

also used to define the generic control components employed with the self-initialization option. 

Input can also be used to compute additional quantities from the normally computed quantities. 

These additional quantities can then be output in major and minor edits and plots. 

Two different card types are available for entering control system data, but only one type can be 

used in a problem. The digits ccc or cccc form the control variable number (i.e., control 

component number). The card format 205cccnn allows 999 control variables, where ccc ranges 

from 001 through 999. The card format 205ccccn allows 9999 control variables, where cccc 

ranges from I through 9999. 

If the self-initialization option is selected, the data cards described in Section A 14.2, Section 

A 14.3.20, and Section A 14.3.21 must be included. If loop flow control is to be included, the 

data cards described in Section A 14.3.19 must also be included. 

A14.2 Card 205cccOO or 205ccecO, Control Component Type Card 

One card must be entered for each of the generic control components when using the self

initialization option. 

W I(A) Alphanumeric name. Enter a name descriptive of the component. This name will appear 

in the printed output along with the component number. A limit of 10 characters is allowed for 

CDC 7600 computers, and a limit of 8 characters is allowed for most other computers. 

W2(A) Control component type. Enter one of the component names, SUM, MUJLT, DIV, 

DIFFRENI, DIFFREND, INTEGRAL, FUNCTION, STDFNCTN, DElAY, TIRIPUNIT, 

TRIPDLAY, POWERI, POWERR, POWERX, PROP-INT, LAG, LEIAD-LAG, CONSTANI', 

SHAFT, PUMPCTL, STFl' AMCTL, or FEEDCTIG., or I)IGITAI,, or the command DEILETE. If 

DELIETE is entered, enter any alphanumeric word in Word I and zeros in the remaining words. 

No other cards are needed when deleting a component. 

W3(R) Scaling factor. For a CONSTAN T component, this quantity is the constant value. No 

additional words are entered on this card, and Cards 205cccOI through 205ccc09 or 205ccccl 

through 205cccc9 are not entered. For the PUMPCTL, STEAMC'II., or FEIFILTI. components, 

this is the gain multiplier (G) for the output signal. 

W4(R) Initial value. 

W5(l) Initial value flag. Zero means no initial condition calculation and W4 is used as the 

initial condition; one means compute initial condition. 

W6(l) LIimiter control. Enter zero, or omit this and the following words if no limits on the 

control variable are to be imposed. Enter I if only a minimum limit is to be imposed, 2 if only a 

maximum limit is to be imposed, and enter 3 if both minimum and maximum limits are to be 

imposed.

42
A14.3.8-1 Digital Component

This component is indicated by DIGITAL in Word 2 of Card 205cccOO or 205ccccO. The 

component is defined by 

Y = S V1 f~tj(t}- t d) 

where t is time and t d is the delay time. 

W I(A) Alphanumeric name of the variable request code for V 1. W2(i) Integer name of the variable request code for V1. W3(R) Sampling time, t, (s). 

W4(R) Delay time, td (s).

43
Appendix B 

Input Decks for the Validation of Model Implementation

45
13. I Input for ANS94-4 Decay Model Validation

1 = Short term decay heat study 

2 configuration Control Problem 3 P Input contains minimum hydrodynamics to allow testing of reactor 

4 * kinetics and decay heat calculation for long time periods. 

6 

7 *1 86 * mod3.2.2 deactivate time control 

8 100 new transnt 

9 104 none 10 301 rktpow 0 

11 302 rkfipow 0 

12 303 rkgapow 0 

13 304 rkreac 0 

14 * time step control 

15 201 100.0 1.0-7 0.01 7 100 10000 10000 

16 

17 0030000 edwards pipe 

18 0030001 2 

19 0030101 4.56037-3,2 

20 0030301 2.04801-1,2 

21 0030601 0,2 

22 0030801 1.177911-6,0,2 

23 0031001 0,2 

24 0031101 0,1 

25 0031201 0,7.0+6,9.78293+5,2.58184+6,0,0,2 

26 0031301 0,0,0,1 

27 * reactivity table 

28 20201100 reac-t 

29 20201101 -1.0,0.0 

30 20201102 0.0,0.0 

31 20201103 5.0,0.0 

32 20201104 5.1,-5.0 

33 20201105 5.2,-5.0 

34 20201106 12.0,-5.0 

35 20201107 12.1,-5.0 

36 20201108 40.0,-5.0 

37 * reactor kinetics input 

38 30000000 point 

39 30000001 gamma-ac 1.0+6 -1.0-20 200.0 1.0 1.0 1.0 52.0 wk 

40 30000002 ans94-4 200.0 0.50 0.05 0.40 0.05 

41 *30000002 ans79-3 200.0 0.50 0.05 0.45 

42 30000011 11 

43 30000401 1.0+6 200.0 wk 0.71 0.13 0.10 0.06 

44 *30000401 1.0+6 200.0 wk 0.81 0.13 0.06 

45 . end of case

46
B.2 Input for Digital Control Model Validation

1 =edward's pipe problem base case with extras and heavy water 

2 Configuration Control Problem 

3 This problem is the same as edhtrk except that heavy water is 4 * used instead of light water. 

6 0000100 new transnt 

7 20800001 dt 0 

8 20800002 dtcrnt 0 

9 20800003 count 0 

10 20800004 errmax 0 

171 20530001 cntrlvar,13 0.1 10 

172 * 

173 20530100 ct1301 digital 1.0 0.0 1 

174 20530101 p, 3 010 00 0 0.05 0.0 

175 * 

176 20530200 ctl302 digital 1.0 0.0 1 

177 20530201 p,3010000 0.10 0.01 

178 20530300 ct1303 lead-lag 10.0 0.0 1 

180 20530301 0.05 0.1 time,0

47
B.3 Input for Validation of Motor Valve Model

=typical pwr model 4 inch cold leg break 36.05 check case configuration control Problem * This problem is a simulation of a four loop presurized reactor " undergoing a small break. Loop containing break is modeled as a "* single loop but the other three loops are coalesced into one loop. 

Modeling does not now follow all recommended modeling practices but "* problem is still good test of many features of code. Problem uses "* standard matrix techniques. 

100 new transnt 

102 british british 

105 5.0 6.0 5000.0 

110 nitrogen

time 

time 

time

0 

0 

0

603 and 509 n 601 or 508 n 602 and 509 n voidg 172010000 

voidg 172010000 

505 and 511 n 505 and 512 n 608 and 604 n 606 xor 605 n 607 and 605 n 592 and 593 n

le 

ge 

ge 

-1.0 

-1.0 

-1.0 

le 

-1.0 

-1.0 

-1.0 

-1.0 

-1.0

null 

null 

null 

null 

null

0 

0 

0

30.0 

10.0 

40.0

n * close n * close 

n * open

0 0.30838 n 0 0.39578 n

120 100010000 0.0 d2o primary 121 170010000 0.0 h2o secnd-1 1 

122 270010000 0.0 h2o secnd-2 1

1850000 

1850101 

1850201 

1850300 18 

1850301 

1850301

"imainstm" valve 

180010000 1860000C 

1 0.0 2914.7 

mtrvlv 

open close rate 

510 501 0.20 

591 691 0.20

13.29 

0.0

0.0 0.0 0100

init trip rate 

1.0 0 0.1 

1.0 0 0.1

48

593 

592 

591 

601 

602 

603 

511 

512 

604 

605 

606 

607 

608 

691 I

I

I
B.4 Input for Validation of Moody Critical Flow Model 

=marviken test 15 (case 1) 

problem type and option 

* option 54 for Moody critical flow model 

* option 50 for Traff-Ransom 

defalt option Henry-Fauske 

1 54 "*1 so

0000100 

0000102 

0000105

new transnt 

si 

3.0 4.0

si

"*120 003010000 0.0 d2o section 

* time step control cards -

dtmin 

1.0e-7 

1.0e-7 

1.Oe-7

dtmax 

0.005 

0.005 

0.250

control 

1 

1 

1

*- minor edit requests

3010000 

3390000 

5060000 

3390000 

5030000 

3390000 

5060000 

9000000 

5050000 

8030000 

8030000 

8020000 

8030000 

8020000 

8030000 

8030000 

8030000 

8030000 

8020000 

9000000 

8030000 

9000000 

8030000 

0 

1 

9000000

* discharge 

* nozzle pressure * discharge

** hydrodynamic components 

* vessel component -

vessel pipe 

39 

0.0 39 

0.0 37 17.0 

3.55 1 1.0 

8.547 1 13.9 

10.767 17 10.373 

10.5 24 10.45 

-90.0 39 

0.0 0.0 

0 39 

000 38

38 

2 0.5 

2 10.036 

18 10.76 

28 10. 319 

39

volume initial conditions 

control pressure quals 2 5.04e6 1.0 

2 5.04e6 1.0 

2 5.04e6 0.00504 

2 5.046e6 0.0 

2 5.050e6 0.0 

2 5.053e6 0.0 

2 5.058e6 0.0 

2 5.061e6 0.0 

control pressure temp 3 5.065e6 537.0 

3 5.069e6 536.5

zero 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

zero 

0.0 

0.0

38 1.26 39 

3 10.501 4 10.8125 13 

19 9.05 20 

37 10.098 38 19.68 39

zero 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

zero 

0.0 

0.0

zero 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

zero 

0.0 

0.0

vol no 1 

2 

3 

4 

5 

6 

7 

8 

vol .no 9 

10

49

*card # 

0000201 

0000202 

0000203

t-end 

5.00 

20.0 

80.0

minor 

20 

50 

2

major 

200 

1000 

40

restart 

4096 

4096 

4096

0000301 

0000302 

0000303 

0000304 

0000305 

0000306 

0000307 

0000308 

0000309 

0000310 

0000311 

0000312 

0000313 

0000314 

0000315 

0000316 

0000317 

0000318 

0000319 

0000320 

0000321 

0000322 

0000323 

0000324 

0000325 

0000326

p 

p 

p rho 

rho 

voidg 

voidg 

mf lowl 

mflow] 

tempf 

tempg 

p 

p 

voidg 

voidg 

rhof 

rhog 

sounde 

voidgl 

voidgj 

sattemp 

velfj 

quale 

cputime 

cntrlvar 

xej

0030000 

0030001 

0030101 

0030201 

0030301 

0030401 

0030402 

0030403 

0030601 

0030801 

0031001 

0031101 

pipe 

*card # 

0031201 

0031202 

0031203 

0031204 

0031205 

0031206 

0031207 

0031208 

*card # 

0031209 

0031210
0031211 

0031212 

0031213 

0031214 

0031215 

0031216 

0031217 

0031218 

0031219 

0031220 

0031221 

0031222 

0031223 

0031224 

0031225 

0031226 

0031227 

0031228 

0031229 

0031230 

0031231 

0031232 

0031233 

0031234 

0031235 

0031236 

0031237 

0031238 

0031239 

* card # 

0031301

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3 

3

5.073e6 

5. 077e6 

5.080e6 

5. 084e6 

5.088e6 

5.092e6 

5.096e6 

5.100e6 

5. 104e6 

5. 108e6 

5.112e6 

5.116e6 

5.120e6 

S. 124e6 

5. 128e6 

5. 132e6 

5. 136e6 

5. 140e6 

5. 144e6 

5. 148e6 

5. 152e6 

5. 156e6 

5.160e6 

5. 164e6 

5.168e6 

5. 172e6 

5. 176e6 

5. 180e6 

5. 188e6

536.3 

536.0 

535.0 

534.2 

532.4 

530.5 

521.9 

513.3 

508.9 

508.9 

508.9 

508.5 

508.5 

508.5 

508.5 

508.0 

508.0 

508.0 

508.0 

508.0 

508.0 

508.0 

508.0 

508.0 

508.0 

508.0 

508.0 

508.0 

508.0

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

37 

38 

39

velf velg vjun jun.no 0.0 0.0 0. 38

single junction outlet from vessel 

0040000 outletj sngljun 0040101 003010000 005000000 2.0 

0040201 0 0.0 0.0 0.0 

* pipe component

0050000 

0050001 

0050102 

0050103 

0050104 

0050201 

0050304 

0050305 

0050306 

0050501 

0050601 

0050801 

0050901 

0051001 

0051103 

0051104 

0051105 

0051106

discharg pip 

6 

0.4441 3 

0.4778 5 

0.4441 6 

0.0 5 

1.1770 3 

0.8890 5 

1.0000 6 

0.0 6 

-90.0 6 

0.0 0.0 

0.0 0.0 

0 6 

1000 2 

1100 3 

1000 4 

1100 5

*card # cntl pressure 

0051221 3 5.197e+6 

0051222 3 5.207e+6 

0051223 3 5.217e+6 

0051224 3 5.225e+6 

0051225 3 5.233e+6 

0051227 3 5.241e+6 

0051300 0 

0051301 0.0 0.0

0.0 0.0 1000

e 

6 5 

temp zero zero zero vol.no 

503.50 0.0 0.0 0.0 1 

499.00 0.0 0.0 0.0 2 

488.00 0.0 0.0 0.0 3 

477.00 0.0 0.0 0.0 4 

460.80 0.0 0.0 0.0 5 

450.50 0.0 0.0 0.0 6

0.0 S

single junction from discharge to nozzle 

0060000 dischj sngljun 0060101 5010000 8000000 0.19634954 0 0 1000 

0060201 0 0.0 0.0 0.0 

nozzle component 

0080000 nozzle pipe 

0080001 3 

0080101 0.196349541 3 

0080201 0.196349541 2 

0080301 0.6000 1 

0080302 0.6000 2 

0080303 0.6090 3 

0080401 0. 3

50
0080501 

0080601 

0080801 

0080901 

0081001 

0081101 

pipe 

*card # 

0081201 

0081202 

0081203

0.0 3 

-90.0 3 

0.0 0.0 

0.0 0.0 2 

0 3 

1000 2 

volume initial condition! 

cntl pressure tempf 3 5.246e+6 450.5 

3 5.252e+6 450.5 

3 5.259e+6 450.5

3 

zero zero zero vol.no 

0.0 0.0 0.0 1 

0.0 0.0 0.0 2 

0.0 0.0 0.0 3

0081300 0 

0081301 0.0 0.0 0.0 2 

single junction outlet from nozzle 

0090000 outltj sngljun 0090101 8010000 7000000 0.19634954 0 0 

*0090101 8010000 7000000 0.19634954 0 0 

*0090101 8010000' 7000000 0.19634954 0 0 0090201 0 0.0 0.0 0.0 

time dependent outlet volume 

0070000 outltv tmdpvol 

0070101 0.2035 1.0 0.0 0.0 -90.0 

0070200 2 

0070201 0.0 1.0+5 1.0 

control variables 

20500100 nozpres sum 1.0 0.0 

20500101 0.0 0.001 p 005060000

000 

0000 1.0 0.0001 0.0 *HEM 

0000 1.0 1000.0 0.0 *FROZEN

-1.0 0.0 0.0 0

1

51
13.5 Input lbr (ANI) J ('hannel Ilow Regime and fI ul I leatup Model Validation 

001 CANDU Fuel Heatup Test 

002 * 003 Sample Input deck developed by B.D.Chung 12/10/1999 

004 + 12 channel with CANDU fuel problem 005 * water and Steam is injected into the channel 

007 * running type 

008 

009 100 new transnt 

010 101 run 011 102 si si 

012 105 2. 4. 

013 110 nitrogen 

014 115 1.0 

015 * 

016 120 100010000 0.0 d2o channel 

017 * 

018 201 500. 1.Oe-6 0.1 3 10 1000 10000 

019 * 

020 minor edit volumes 

021 

022 alp num 023 

024 301 p 100010000 * channel in pressure 025 302 p 100120000 * channel out pressure 026 311 voidg 100010000 

027 312 voidg 100120000 

028 321 mflow) 018000000 * channel inlet flow 

029 322 mflowj 101000000 channel outlet flow 

030 * 

031 335 cntrlvar 1 

032 336 cntrlvar 2 

033 337 floreg 100060000 

034 * 

035 340 htmode 100100801 

036 341 htmode 100200801 

037 350 hthtc 100100801 

038 351 hthtc 100200801 

039 360 httemp 100100806 

040 361 httemp 100200806 

041 * 

042 * * * * ******** ,*********   **  .*** * * ** *- * 

043 * 

044 0170000 feedliq tmdpvol 045 0170101 10.0 0.0 1000.0 0.0 0.0 0.0 0.0 0.0 0 

046 0170200 202 

047 0170201 0.0 10.69e6 0.0 

048 0170202 50000.0 10.69e6 0.0 

049 * 

050 0180000 feedjun tmdpjun 051 0180101 017000000 100000000 0 

052 * natural circulation 1% 

053 0180200 0 

054 0180201 0. 0.1 0.0 0. jf 

055 * 

056 0190000 feesteam tmdpvol 057 0190101 10.0 0.0 1000.0 0.0 0.0 0.0 0.0 0.0 0 

058 0190200 202 

059 0190201 0.0 10.69e6 1.0 

060 0190202 50000.0 10.69e6 1.0 

061 * 

062 0200000 feedjun tmdpjun 063 0200101 019000000 100000000 0 

064 * natural circulation 1% 

065 0200200 0 

066 0200201 0. 0.00 0.0 0. *jg 

067 * ** .** * * 

068 * Heated Section Pipe 069 * 

070 1000000 chani canchan 

071 1000001 12 

072 1000101 0.330125 12 

073 1000101 8.397-03 12 

074 1000201 0.0 11 

075 1000301 0.4953 12 

076 1000401 0.0 12 

077 1000501 0.0 12 

078 1000601 0.0 12 

079 1000701 0.0 12 

080 1000801 4.Se-5 0.007518 12 

081 1000901 0.939 0.939 11 

082 1001001 100 12

52
083 1001101 100 11 

084 1001201 202 10.69e6 0.0 0. 0. 0. 12 

085 1001300 1 

086 1001301 0.0 0.0 0.0 11 

087 * Dj 

088 1001401 0.007518 0.0 1.0 1.0 11 

089 * 

090 1010000 jun882 sngljun 091 1010101 100010000 102000000 0.0 0.10 0.10 100 

092 1010102 0.61 0.61 0.61 

093 1010201 1 0.0 0.0 0.0 

094 * 

095 1020000 outvol tmdpvol 096 1020101 10.0 0.0 1000.0 0.0 0.0 0.0 0.0 0.0 0 

097 1020200 203 

098 1020201 0.0 10.69e6 562.0 

099 1020202 50000.0 10.69e6 562.0 

100 * 

101 * 

102 * heat structure of channel 1 core 

103 

104 * top 18 fuel rods 

105 * 

106 11001000 12 6 2 1 0.0 

107 11001100 0 1 

108 11001101 3 0.0061 

109 11001102 1 0.00615 

110 11001103 1 0.00655 

111 11001201 3 3 

112 11001202 6 4 

113 11001203 4 5 

114 11001301 1.0 5 

115 11001400 0 

116 11001401 1000.0 4 600.0 5 590.0 6 

117 *11001501 0 0 0 1 1740.98 12 

118 *11001601 100010000 10000 124 1 1740.98 12 

119 11001501 0 0 0 1 18.00 12 

120 11001601 100010000 10000 124 1 18.00 12 

121 11001701 50 0.0231 0.0 0.0 1 

122 11001702 50 0.0570 0.0 0.0 2 

123 11001703 50 0.0840 0.0 0.0 3 

124 11001704 50 0.1026 0.0 0.0 4 

125 11001705 50 0.1157 0.0 0.0 5 

126 11001706 50 0.1235 0.0 0.0 6 

127 11001707 50 0.1235 0.0 0.0 7 

128 11001708 50 0.1158 0.0 0.0 8 

129 11001709 50 0.1009 0.0 0.0 9 

130 11001710 50 0.0798 0.0 0.0 10 

131 11001711 50 0.0528 0.0 0.0 11 

132 11001712 50 0.0213 0.0 0.0 12 

133 11001801 0.0 10.0 10.0 0.0 0.0 0.0 0.0 1.0 12 

134 * 

135 *11001901 0.0 10.0 10.0 0.0 0.0 0.0 0.0 1.0 12 

136 * if 124 option, word 10 is the relative elevation 

137 of fuel in a channel -1.0 < z < 1.0 

138 * 

139 11001900 1 * 12 word format 

140 11001901 0.0 10.0 10.0 0.0 0.0 0.0 0.0 1.0 

141 + 0.0 0.5 1.0 12 

142 * 

143 * bottom 19 fuel rods 

144 * 

145 11002000 12 6 2 1 0.0 

146 11002100 0 1 

147 11002101 3 0.0061 

148 11002102 1 0.00615 

149 11002103 1 0.00655 

150 11002201 3 3 

1.51 11002202 6 4 

152 11002203 4 5 

153 11002301 1.0 5 

154 11002400 0 

155 11002401 1000.0 4 600.0 5 590.0 6 

156 *11001501 0 0 0 1 1740.98 12 

157 *11001601 100010000 10000 124 1 1740.98 12 

158 11002S01 0 0 0 1 19.00 12 

159 11002601 100010000 10000 124 1 19.00 12 

160 11002701 50 0.0231 0.0 0.0 1 

161 11002702 50 0.0570 0.0 0.0 2 

162 11002703 50 0.0840 0.0 0.0 3 

163 11002704 50 0.1026 0.0 0.0 4 

164 11002705 50 0.1157 0.0 0.0 5 

165 11002706 SO 0.1235 0.0 0.0 6 

166 11002707 50 0.1235 0.0 0.0 7 

167 11002708 50 0.1158 0.0 0.0 8 

168 11002709 50 0.1009 0.0 0.0 9 

169 11002710 50 0.0798 0.0 0.0 10

53
170 11002711 50 0.0528 0.0 0.0 11 

171 11002712 50 0.0213 0.0 0.0 12 172 11002801 0.0 10.0 10.0 0.0 0.0 0.0 0.0 1.0 12 173 * 

174 *11002901 0.0 10.0 10.0 0.0 0.0 0.0 0.0 1.0 12 175 * if 124 option, word 10 is the relative elevation 

176 * of fuel in a channel -1.0 < z < 1.0 

177 * 

178 11002900 1 * 12 word format 

179 11002901 0.0 10.0 10.0 0.0 0.0 0.0 0.0 1.0 

180 f 0.0 -0.5 1.0 12 

181 heat structure of channel 1 pressure tube 

182 

183 11102000 12 2 2 1 0.05190 

184 11102100 0 1 

185 11102101 1 0.056332 

186 11102201 4 1 

187 11102301 0.0 1 

188 11102400 0 

189 11102401 570.0 2 

190 11102501 100010000 10000 1 1 47.0535 12 191 11102601 0 0 0 1 47.0535 12 192 11102501 100010000 10000 1 1 1.00 12 193 11102601 0 0 0 1 1.00 12 194 11102701 0 0.0 0.0 0.0 12 195 11102801 0.0 10.0 10.0 0.0 0.0 0.0 0.0 1.0 12 196 11102901 0.0 10.0 10.0 0.0 0.0 0.0 0.0 1.0 12 

197 

198 

199 

200 * heat structure thermal property data 

201 * 

20 2 * . .. .... .. ..... . . 203 

204 20100100 c-steel * carbon steel 205 20100200 tbl/fctn 1 1 * stainless steel 206 20100300 tbl/fctn 1 1 * uo2 207 20100400 tbl/fctn 1 1 * zircaloy 208 20100500 tbl/fctn 1 1 * inconel-800 

209 20100600 tbl/fctn 1 1 * gap 210 * 

211 * 

212 *

213 * stainless steel property 214 

215 * temperature conductivity 216 * 

217 20100201 273.15 12.98 

218 20100202 1199.82 25.1 

219 * 

220 * temperature heat capacity 221 * 

222 20100251 273.15 3.83e6 

223 20100252 366.5 3.83e6 

224 20100253 477.59 4.19e6 

225 20100254 588.59 4.336e6 

226 20100255 699.82 4.504e6 

227 20100256 810.93 4.6 3 9e6 

228 20100257 922.04 4.773e6 

229 20100258 1144.26 5.076e6 

230 20100259 1366.5 5.376e6 

231 20100260 1477.59 5.546e6 

232 

233 * 

234 * u02 Thernal conductivity 

235 

236 Temp. Thermal conductivity 237 

238 20100301 2.7315e2 8.44 

239 20100302 4.1667e2 6.46 

240 20100303 5.3315e2 5.782385 

241 20100304 6.99817e2 4.633177 

242 20100305 8.66483e2 3.880307 

243 20100306 1.03315e3 3.357625 

244 20100307 1.08871e3 3.155129 

245 20100308 1.19982e3 2.983787 

246 20100309 1.28315e3 2.836674 

247 20100310 1.36648e3 2.713792 

248 20100311 1.53315e3 2.521680 

249 20100312 1.61648e3 2.448990 

250 20100313 1.69982e3 2.391875 

251 20100314 1.97759e3 2.289762 

252 20100315 2 .25537e3 2.307069 

253 20100316 2.53315e3 2.433413 

254 20100317 2.81093e3 2.661870 

255 20100318 3.08871e3 2.994171 

256 *-

54
257 Temp. Thermal Conductivity 

258 *

259 20100351 2.7315e2 2.319427e6 

260 20100352 3.23150e2 2.571985e6 

261 20100353 3.73150e2 2.746357e6 

262 20100354 6.73150e2 3.138694e6 

263 20100355 1.37315e3 3.443844e6 

264 20100356 1.77315e3 3.531030e6 

265 20100357 1.97315e3 3.792588e6 

266 20100358 2.17315e3 4.228518e6 

267 20100359 2.37315e3 4.882412e6 

268 20100360 2.67315e3 6.015829e6 

269 20100361 2.77315e3 6.320980e6 

270 20100362 2.87315e3 6.582538e6 

271 20100363 2.97315e3 6.713317e6 

272 20100364 3.11315e3 6.800503e6 

273 20100365 4.69982e3 6.800503e6 

274 * 

275 * 

276 * 

277 * zircoly Thermal Property 

278 * 

279 20100401 273.0 12.5 

280 20100402 380.4 13.6 

281 20100403 469.3 14.6 

282 20100404 57).6 15.8 

283 20100405 685.9 17.3 

284 20100406 774.8 18.4 

285 20100407 872.0 19.8 

286 20100408 973.2 21.8 

287 20100409 1073.2 23.2 

288 20100410 1123.2 25.4 

289 20100411 1152.3 24.2 

290 20100412 1232.2 25.5 

291 20100413 1331.2 26.6 

292 20100414 1404.2 28.2 

293 20100415 1576.2 33.0 

294 20100416 1625.2 36.7 

295 20100417 1755.2 41.2 

296 20100418 2273.2 55.0 

297 * 

298 20100451 300.0 1.841e6 

299 20100452 400.0 1.978e6 

300 20100453 640.0 2.168e6 

301 20100454 1090.0 2.456e6 

302 20100455 1093.0 3.288e6 

303 20100456 1113.0 3.865e6 

304 20100457 1133.0 4.028e6 

305 20100458 1153.0 4.709e6 

306 20100459 1173.0 5.345e6 

307 20100460 1193.0 5.044e6 

308 20100461 1213.0 4.054e6 

309 20100462 1233.0 3.072e6 

310 20100463 1243.0 2.332e6 

311 20100464 1477.0 2.332e6 

312 * 

313 * Constant value for Inconel-800 

314 * 

315 20100501 47.1 

316 20100551 3.688e6 

317 * 

318 * Constant value for Gap 

319 * 

320 20100601 0.278 

321 20100651 363.51 

322 * 

323 * 

324 * total thermal power = 2111.5Mw (4 loops) 

325 20205000 power 

326 20205001 -1.0 531.875e+6 

327 20205002 0.0 531.875e+6 

328 20205003 20000.0 531.875ei6 

329 * 

330 * 

331 * dacay thermal power 2111.5Mw x O.1 % (4 loops) 

332 20205000 power 

333 20205001 -1.0 50.Oe+4 

334 20205002 0.0 50.0e+4 

335 20205003 20000.0 50.0eý4 

336 * 

337 20205001 -1.0 20.e+4 

338 20205002 0.0 20.e+4 

339 20205003 20000.0 20.e+4 

340 * 

341 20500100 jg mult 1.0 0.0 1 

342 20500101 voidg 100060000 velg 100060000 

343 20500200 jf mult 1.0 0.0 1 

344 20500201 voidf 100060000 velf 100060000

55
NRC FORM 335 U.S. NUCLEAR REGULATORY COMMISSION 1. REPORT NUMBER 

(2-89) (Assigned by NRC, Add Vol.. Supp., Rev.. NRCM 1102, BIBLIOGRAPHIC DATA SHEET and Addendum Numbers, If any.) 3201.,3202 BBIGAHCDT HE 

(See instructions on the reverse) 

2. TITLE AND SUBTITLE NUREG/IA-0189 

Improvements of RELAP5/MOD3.2.2 Models for the CANDU Plant Analysis 3. DATE REPORT PUBLISHED 

MONTH - YEAR 

October 2000 

4. FIN OR GRANT NUMBER 

5. AUTHOR(S) 6. TYPE OF REPORT 

B.D. Chung, W.J. Lee, KAERI Technical 

Y.S. Bang, KINS Technical 

7. PERIOD COVERED (Inclusive Dates) 

8. PERFORMING ORGANIZATION - NAME AND ADDRESS (If NRC. provide Division, Office or Region, U.S. Nuclear Regulatory Commission, and mailing address: if contracto, 

provide name and mailing address.) 

Korea Atomic Energy Research Institute Korea Institute of Nuclear Safety 

P.O. Box 105 P.O. Box 114 

Yusung, Daejon, 305-600 Yuseong-Gu, Taejon, 305-600 

KOREA KOREA

9. SPONSORING ORGANIZATION - NAME AND ADDRESS (If NRC, type 'Same as above'; f contractor, provide NRC Division, Office or Region, U.S. Nuclear Regulatory Commission, 

and mailing address.)

Division of Systems Analysis and Regulatory Effectiveness 

Office of Nuclear Regulatory Research 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001

1U. SUPPLEMENTARY NNUTE

11. ABSTRACT (200 words or less) 

The main purpose of this study is to develop a thermal hydraulic auditing analysis code for CANDU reactor by extending the 

model of current RELAP5/MOD3, which have been used for a long time as an auditing analysis took of Light Water Reactors (LWR). The major thermal hydraulic phenomena for the key CANDU events and the modeling limitation of the current 

RELAP5/MOD3 for CANDU applications are based on the previous study on the applicability of RELAP5 code to the 

CANDU-type plants. The seven models are improved: the CANDU fuel channel heat transfer model; the horizontal flow regime model; the digital control model; ANS94-4 decay heat model; Moody critical model; motor operative valve model; and 

pressurizer spray model. The models are improved and developed on generic base, thus, they also could be applicable to 

PWR. Especially, the plutonium contribution to decay heat can be considered by the ANS94-4 decay heat model. The Moody critical flow model using a heavy water property can provide an additional capability to evaluate the conservative break flow in 

CANDU system. Simulation of different rate of opening and closing the motor valve is now possible when calculating the liquid relief valve behavior during transient. And the new pressurizer spray model can be used for evaluating the droplet size effect on the condensation. All of those improvements are verified through some assessments with simple conceptual problems and 

Marviken critical flow test. The new code is based on the RELAP5/MOD3.2.2 gamma version, and written in FORTRAN 90 

language.

12. KEY WORDS/DESCRIPTORS (List words or phrases that will assist researchers in locating the report.) 13. AVAILABILITY STATEMENT 

RELAP5/MOD3.2.2 unlimited 

CANDU 14. SECURITY CLASSIFICATION 

(This Page) 

unclassified 

(This Report) 

unclassified 

15. NUMBER OF PAGES 

16. PRICE

NRC FORM 335 (2-89) This form was electronically produced by Elite Federal Forrms, Inc.
•pPrinted 

Ion recycled' 

palper'u" 

Federal Recycling Program
IMPROVEMENTS OF RELAP5/MOD3.2.2 MODELS 

FOR THE CANDU PLANT ANALYSIS

OCTOBER 2000

UNITED STATES 

NUCLEAR REGULATORY COMMISSION 

WASHINGTON, D.C, 20555-0001

years

NUREG/IA- 0189