NUREG/IA-0251 

 International 

 Agreement Report

 

Improvement of RELAP5/MOD3.3 

Reflood Model Based on the 

Assessments against FLECHT-SEASET 

Tests 

Prepared by: 

Tong-Soo Choi, Chang-Hwan Ban 

KEPCO Nuclear Fuel 

Daejeon, Korea 

Dong-Gu Kang, Seung-Hoon Ahn 

Korea Institute of Nuclear Safety 

Daejeon, Korea 

A. Calvo, NRC Project Manager 

Office of Nuclear Regulatory Research 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001 

February 2011 

 

Prepared as part of 

The Agreement on Research Participation and Technical Exchange 

Under the International Code Assessment and Maintenance Program (CAMP) 

 

Published by 

U.S. Nuclear Regulatory Commission
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NUREG/IA-0251

Improvement of RELAP5/MOD3.3 Reflood 

Model Based on the Assessments against 

FLECHT-SEASET Tests

Manuscript Completed: September 2010

Date Published: February 2011

Prepared by:

Tong-Soo Choi, Chang-Hwan Ban

KEPCO Nuclear Fuel

Daejeon, Korea

Dong-Gu Kang, Seung-Hoon Ahn

Korea Institute of Nuclear Safety

Daejeon, Korea

Antony Calvo, NRC Project Manager

U.S. Nuclear Regulatory Commission

Washington, DC, United Sates of America

Prepared for:

Division of Systems Analysis

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

Washington, DC 20555-0001 
iii

ABSTRACT

The reflood model of RELAP5/MOD3.3 was assessed against eight selected FLECHT-SEASET 

tests. Comparisons of predicted and measured peak cladding temperatures and quench times 

indicated that the code predicts peak cladding temperatures relatively well. However, rod 

quenches were predicted to occur too early. To improve the predictability for quench times, we 

carefully reviewed and modified the wall-to-fluid heat transfer models for the film boiling regime. 

After the modifications, the same set of eight FLECHT-SEASET tests was simulated again to 

show that the modifications made in this study improve the code’s predictability not only for 

quench times but also for peak clad temperatures. The modifications reduced the RMS error in 

the prediction of peak clad temperatures and quench times from 48.3 to 36.7 K and 85.9 to 32.1

seconds, respectively.

v

FOREWORD

RELAP5 is one of the best-estimate safety codes to date. It was developed by United States 

Nuclear Regulatory Commission (USNRC) and RELAP5/MOD3.3 (patch 03), released in 2006,

is its latest version. Though USNRC has been moving most of their developmental efforts from 

RELAP5 to TRACE, the code has been widely applied to analyze system transients of 

Pressurized Water Reactors (PWRs), including the postulated large break loss-of-coolant 

accident (LBLOCA). 

A few years ago, three Korean organizations, Korea Atomic Energy Research Institute (KAERI), 

Korea Electric Power Research Institute (KEPRI), and Korea Nuclear Fuel (KNF), succeeded to 

co-develop a best-estimate LBLOCA evaluation model using a modified version of 

RELAP5/MOD3.1. And now, KNF is trying to extend the best-estimate evaluation model by 

adopting RELAP5/MOD3.3 because it has several new models or improvements to existing 

models, and user conveniences compared to (a modified version of) RELAP5/MOD3.1.

To develop a best estimate evaluation model for LBLOCA analyses using a code, we have to 

show how accurately the code predicts important phenomena occurring in that accident by 

comparing the code predictions to various separate effect test data and that is why we tried to 

assess the reflood model of RELAP5/MOD3.3 against FLECHT-SEASET tests. 

This report was prepared basically to record the results that we obtained from the 

RELAP5/MOD3.3 assessment using the FLECHT-SEASET test data. By the way, we had to 

modify the code because the code was appraised to have some deficiencies in the reflood wallto-fluid heat transfer models. So, this report explains also the code modifications we made and 

their effect on the code’s predictive capability.

The code modifications suggested in this report makes the code predict much better the peak 

clad temperatures and quench times of FLECHT-SEASET tests. However, the reflood model of 

RELAP5/MOD3.3 should be further improved because the code does not show good predictive 

capability for some test conditions even with the modifications. Thus, this study needs to be 

followed by such improvements as the addition of a spacer grid heat transfer model. 

vii

CONTENTS

Page

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

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

Acknowledgement .................................................................................................................xv

Executive Summary...............................................................................................................xvii

Abbreviations......................................................................................................................... xix

Nomenclature ....................................................................................................................... xxi

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

2. Assessment of Original Reflood Model.............................................................................3

2.1 FLECHT-SEASET Tests ..............................................................................................3

2.2 RELAP5 Model ...........................................................................................................4

2.3 Assessment Results .....................................................................................................5

3. Modification of Film Boiling Wall-to-Fluid Heat Transfer Model.....................................15

3.1 Brief of Current Models...............................................................................................15

3.2 Modified Models ........................................................................................................16

3.3 Coding Error Corrections ............................................................................................19

3.4 Effect of Modifications.................................................................................................19

4. Conclusions.......................................................................................................................27

5. References.........................................................................................................................29

Appendix: RELAP5 Base Deck for FLECHT-SEASET Test 31805 ....................................115
viii

LIST OF FIGURES

Page

1. Facility Flow Diagram for Forced Reflood Tests ...........................................................31

2. Cross-sectional View of Bundle Heated Section ............................................................32

3. Axial Power Profile of Heater Rods................................................................................32

4. FLECHT-SEASET RELAP5 Noding Diagram ................................................................33

5. Effect of Axial Noding on Quench Front Elevation..........................................................34

6. Rod Clad Temperatures at 2 ft from Heated Bottom for Test 31805 ...............................34

7. Rod Clad Temperatures at 4 ft from Heated Bottom for Test 31805 ...............................35

8. Rod Clad Temperatures at 6 ft from Heated Bottom for Test 31805 ...............................35

9. Rod Clad Temperatures at 6.5 ft from Heated Bottom for Test 31805 ............................36

10. Rod Clad Temperatures at 8 ft from Heated Bottom for Test 31805 ...............................36

11. Rod Clad Temperatures at 10 ft from Heated Bottom for Test 31805 .............................37

12. Rod Clad Temperatures at 11 ft from Heated Bottom for Test 31805 .............................37

13. Rod Clad Temperatures at 11.5 ft from Heated Bottom for Test 31805...........................38

14. Vapor Temperatures at 6 ft from Heated Bottom for Test 31805.....................................38

15. Vapor Temperatures at 10 ft from Heated Bottom for Test 31805...................................39

16. Quench Profile as a Function of Time for Test 31805.....................................................39

17. Differential Pressure for the Entire 12 ft Core for Test 31805 .........................................40

18. Differential Pressure at 6~7 ft Elevation for Test 31805..................................................40

19. Differential Pressure at 10~11 ft Elevation for Test 31805..............................................41

20. Heat Transfer Coefficient at 4 ft from Heated Bottom for Test 31805 .............................41

21. Heat Transfer Coefficient at 6 ft from Heated Bottom for Test 31805 .............................42

22. Heat Transfer Coefficient at 6.5 ft from Heated Bottom for Test 31805 ..........................42

23. Heat Transfer Coefficient at 8 ft from Heated Bottom for Test 31805 .............................43

24. Heat Transfer Coefficient at 10 ft from Heated Bottom for Test 31805 ...........................43

25. Rod Clad Temperatures at 2 ft from Heated Bottom for Test 31504 ...............................44

26. Rod Clad Temperatures at 4 ft from Heated Bottom for Test 31504 ...............................44

27. Rod Clad Temperatures at 6 ft from Heated Bottom for Test 31504 ...............................45

28. Rod Clad Temperatures at 6.5 ft from Heated Bottom for Test 31504 ............................45

29. Rod Clad Temperatures at 8 ft from Heated Bottom for Test 31504 ...............................46

30. Rod Clad Temperatures at 10 ft from Heated Bottom for Test 31504 .............................46

31. Rod Clad Temperatures at 11 ft from Heated Bottom for Test 31504 .............................47

32. Rod Clad Temperatures at 11.5 ft from Heated Bottom for Test 31504...........................47

33. Vapor Temperatures at 6 ft from Heated Bottom for Test 31504.....................................48

34. Vapor Temperatures at 10 ft from Heated Bottom for Test 31504...................................48
ix

35. Quench Profile as a Function of Time for Test 31504.....................................................49

36. Differential Pressure for the Entire 12 ft Core for Test 31504 .........................................49

37. Differential Pressure at 6~7 ft Elevation for Test 31504..................................................50

38. Differential Pressure at 10~11 ft Elevation for Test 31504..............................................50

39. Heat Transfer Coefficient at 4 ft from Heated Bottom for Test 31504 .............................51

40. Heat Transfer Coefficient at 6 ft from Heated Bottom for Test 31504 .............................51

41. Heat Transfer Coefficient at 6.5 ft from Heated Bottom for Test 31504 ..........................52

42. Heat Transfer Coefficient at 8 ft from Heated Bottom for Test 31504 .............................52

43. Heat Transfer Coefficient at 10 ft from Heated Bottom for Test 31504 ...........................53

44. Rod Clad Temperatures at 2 ft from Heated Bottom for Test 31203 ...............................53

45. Rod Clad Temperatures at 4 ft from Heated Bottom for Test 31203 ...............................54

46. Rod Clad Temperatures at 6 ft from Heated Bottom for Test 31203 ...............................54

47. Rod Clad Temperatures at 6.5 ft from Heated Bottom for Test 31203 ............................55

48. Rod Clad Temperatures at 8 ft from Heated Bottom for Test 31203 ...............................55

49. Rod Clad Temperatures at 10 ft from Heated Bottom for Test 31203 .............................56

50. Rod Clad Temperatures at 11 ft from Heated Bottom for Test 31203 .............................56

51. Rod Clad Temperatures at 11.5 ft from Heated Bottom for Test 31203...........................57

52. Vapor Temperatures at 6 ft from Heated Bottom for Test 31203.....................................57

53. Vapor Temperatures at 10 ft from Heated Bottom for Test 31203...................................58

54. Quench Profile as a Function of Time for Test 31203.....................................................58

55. Differential Pressure for the Entire 12 ft Core for Test 31203 .........................................59

56. Differential Pressure at 6~7 ft Elevation for Test 31203..................................................59

57. Differential Pressure at 10~11 ft Elevation for Test 31203..............................................60

58. Heat Transfer Coefficient at 4 ft from Heated Bottom for Test 31203 .............................60

59. Heat Transfer Coefficient at 6 ft from Heated Bottom for Test 31203 .............................61

60. Heat Transfer Coefficient at 6.5 ft from Heated Bottom for Test 31203 ..........................61

61. Heat Transfer Coefficient at 8 ft from Heated Bottom for Test 31203 .............................62

62. Heat Transfer Coefficient at 10 ft from Heated Bottom for Test 31203 ...........................62

63. Rod Clad Temperatures at 2 ft from Heated Bottom for Test 31302 ...............................63

64. Rod Clad Temperatures at 4 ft from Heated Bottom for Test 31302 ...............................63

65. Rod Clad Temperatures at 6 ft from Heated Bottom for Test 31302 ...............................64

66. Rod Clad Temperatures at 6.5 ft from Heated Bottom for Test 31302 ............................64

67. Rod Clad Temperatures at 8 ft from Heated Bottom for Test 31302 ...............................65

68. Rod Clad Temperatures at 10 ft from Heated Bottom for Test 31302 .............................65

69. Rod Clad Temperatures at 11 ft from Heated Bottom for Test 31302 .............................66

70. Rod Clad Temperatures at 11.5 ft from Heated Bottom for Test 31302...........................66
x

71. Vapor Temperatures at 6 ft from Heated Bottom for Test 31302.....................................67

72. Vapor Temperatures at 10 ft from Heated Bottom for Test 31302...................................67

73. Quench Profile as a Function of Time for Test 31302.....................................................68

74. Differential Pressure for the Entire 12 ft Core for Test 31302 .........................................68

75. Differential Pressure at 6~7 ft Elevation for Test 31302..................................................69

76. Differential Pressure at 10~11 ft Elevation for Test 31302..............................................69

77. Heat Transfer Coefficient at 4 ft from Heated Bottom for Test 31302 .............................70

78. Heat Transfer Coefficient at 6 ft from Heated Bottom for Test 31302 .............................70

79. Heat Transfer Coefficient at 6.5 ft from Heated Bottom for Test 31302 ..........................71

80. Heat Transfer Coefficient at 8 ft from Heated Bottom for Test 31302 .............................71

81. Heat Transfer Coefficient at 10 ft from Heated Bottom for Test 31302 ...........................72

82. Rod Clad Temperatures at 2 ft from Heated Bottom for Test 31701 ...............................72

83. Rod Clad Temperatures at 4 ft from Heated Bottom for Test 31701 ...............................73

84. Rod Clad Temperatures at 6 ft from Heated Bottom for Test 31701 ...............................73

85. Rod Clad Temperatures at 6.5 ft from Heated Bottom for Test 31701 ............................74

86. Rod Clad Temperatures at 8 ft from Heated Bottom for Test 31701 ...............................74

87. Rod Clad Temperatures at 10 ft from Heated Bottom for Test 31701 .............................75

88. Rod Clad Temperatures at 11 ft from Heated Bottom for Test 31701 .............................75

89. Rod Clad Temperatures at 11.5 ft from Heated Bottom for Test 31701...........................76

90. Vapor Temperatures at 6 ft from Heated Bottom for Test 31701.....................................76

91. Vapor Temperatures at 10 ft from Heated Bottom for Test 31701...................................77

92. Quench Profile as a Function of Time for Test 31701.....................................................77

93. Differential Pressure for the Entire 12 ft Core for Test 31701 .........................................78

94. Differential Pressure at 6~7 ft Elevation for Test 31701..................................................78

95. Differential Pressure at 10~11 ft Elevation for Test 31701..............................................79

96. Heat Transfer Coefficient at 4 ft from Heated Bottom for Test 31701 .............................79

97. Heat Transfer Coefficient at 6 ft from Heated Bottom for Test 31701 .............................80

98. Heat Transfer Coefficient at 6.5 ft from Heated Bottom for Test 31701 ..........................80

99. Heat Transfer Coefficient at 8 ft from Heated Bottom for Test 31701 .............................81

100. Heat Transfer Coefficient at 10 ft from Heated Bottom for Test 31701 ...........................81

101. Rod Clad Temperatures at 2 ft from Heated Bottom for Test 31108 ...............................82

102. Rod Clad Temperatures at 4 ft from Heated Bottom for Test 31108 ...............................82

103. Rod Clad Temperatures at 6 ft from Heated Bottom for Test 31108 ...............................83

104. Rod Clad Temperatures at 6.5 ft from Heated Bottom for Test 31108.............................83

105. Rod Clad Temperatures at 8 ft from Heated Bottom for Test 31108 ...............................84

106. Rod Clad Temperatures at 10 ft from Heated Bottom for Test 31108..............................84
xi

107. Rod Clad Temperatures at 11 ft from Heated Bottom for Test 31108..............................85

108. Rod Clad Temperatures at 11.5 ft from Heated Bottom for Test 31108...........................85

109. Vapor Temperatures at 6 ft from Heated Bottom for Test 31108.....................................86

110. Vapor Temperatures at 10 ft from Heated Bottom for Test 31108 ...................................86

111. Quench Profile as a Function of Time for Test 31108.....................................................87

112. Differential Pressure for the Entire 12 ft Core for Test 31108 .........................................87

113. Differential Pressure at 6~7 ft Elevation for Test 31108..................................................88

114. Differential Pressure at 10~11 ft Elevation for Test 31108 ..............................................88

115. Heat Transfer Coefficient at 4 ft from Heated Bottom for Test 31108..............................89

116. Heat Transfer Coefficient at 6 ft from Heated Bottom for Test 31108..............................89

117. Heat Transfer Coefficient at 6.5 ft from Heated Bottom for Test 31108...........................90

118. Heat Transfer Coefficient at 8 ft from Heated Bottom for Test 31108..............................90

119. Heat Transfer Coefficient at 10 ft from Heated Bottom for Test 31108............................91

120. Rod Clad Temperatures at 2 ft from Heated Bottom for Test 32013 ...............................91

121. Rod Clad Temperatures at 4 ft from Heated Bottom for Test 32013 ...............................92

122. Rod Clad Temperatures at 6 ft from Heated Bottom for Test 32013 ...............................92

123. Rod Clad Temperatures at 6.5 ft from Heated Bottom for Test 32013 ............................93

124. Rod Clad Temperatures at 8 ft from Heated Bottom for Test 32013 ...............................93

125. Rod Clad Temperatures at 10 ft from Heated Bottom for Test 32013 .............................94

126. Rod Clad Temperatures at 11 ft from Heated Bottom for Test 32013 .............................94

127. Rod Clad Temperatures at 11.5 ft from Heated Bottom for Test 32013...........................95

128. Vapor Temperatures at 6 ft from Heated Bottom for Test 32013.....................................95

129. Vapor Temperatures at 10 ft from Heated Bottom for Test 32013...................................96

130. Quench Profile as a Function of Time for Test 32013.....................................................96

131. Differential Pressure for the Entire 12 ft Core for Test 32013 .........................................97

132. Differential Pressure at 6~7 ft Elevation for Test 32013..................................................97

133. Differential Pressure at 10~11 ft Elevation for Test 32013..............................................98

134. Heat Transfer Coefficient at 4 ft from Heated Bottom for Test 32013 .............................98

135. Heat Transfer Coefficient at 6 ft from Heated Bottom for Test 32013 .............................99

136. Heat Transfer Coefficient at 6.5 ft from Heated Bottom for Test 32013 ..........................99

137. Heat Transfer Coefficient at 8 ft from Heated Bottom for Test 32013 ...........................100

138. Heat Transfer Coefficient at 10 ft from Heated Bottom for Test 32013 .........................100

139. Rod Clad Temperatures at 2 ft from Heated Bottom for Test 32114 .............................101

140. Rod Clad Temperatures at 4 ft from Heated Bottom for Test 32114 .............................101

141. Rod Clad Temperatures at 6 ft from Heated Bottom for Test 32114 .............................102

142. Rod Clad Temperatures at 6.5 ft from Heated Bottom for Test 32114...........................102
xii

143. Rod Clad Temperatures at 8 ft from Heated Bottom for Test 32114 .............................103

144. Rod Clad Temperatures at 10 ft from Heated Bottom for Test 32114............................103

145. Rod Clad Temperatures at 11 ft from Heated Bottom for Test 32114............................104

146. Rod Clad Temperatures at 11.5 ft from Heated Bottom for Test 32114.........................104

147. Vapor Temperatures at 6 ft from Heated Bottom for Test 32114...................................105

148. Vapor Temperatures at 10 ft from Heated Bottom for Test 32114 .................................105

149. Quench Profile as a Function of Time for Test 32114...................................................106

150. Differential Pressure for the Entire 12 ft Core for Test 32114 .......................................106

151. Differential Pressure at 6~7 ft Elevation for Test 32114................................................107

152. Differential Pressure at 10~11 ft Elevation for Test 32114 ............................................107

153. Heat Transfer Coefficient at 4 ft from Heated Bottom for Test 32114............................108

154. Heat Transfer Coefficient at 6 ft from Heated Bottom for Test 32114............................108

155. Heat Transfer Coefficient at 6.5 ft from Heated Bottom for Test 32114.........................109

156. Heat Transfer Coefficient at 8 ft from Heated Bottom for Test 32114............................109

157. Heat Transfer Coefficient at 10 ft from Heated Bottom for Test 32114..........................110

158. Percent Deviations of Predicted PCTs with Original Version........................................110

159. Differences in Quench Times with Original Version...................................................... 111

160. Percent Deviations of Predicted PCTs with Modified Version....................................... 111

161. Effect of Modifications on PCT Predictions ..................................................................112

162. Comparison of Predictability for PCTs..........................................................................112

163. Differences in Quench Times with Modified Version ....................................................113

164. Effect of Modifications on Quench Time Predictions ....................................................113

165. Comparison of Predictability for Quench Times ...........................................................114
xiii

LIST OF TABLES

Page

1. FLEHT-SEASET Tests for RELAP5 Assessment ...........................................................30

xv

ACKNOWLEDGEMENTS

This study utilized the experimental data which was processed during the KNF-USNRC co-work 

for assessing the reflood model of TRACE. The authors are grateful to the participants of that 

co-work (J. H. Jeong of KNF and G. Rhee of USNRC). The authors also acknowledge the 

financial support of the National Research Foundation under the national mid-and-long-term 

nuclear research and development program of the Ministry of Education, Science and 

Technology of the Rebublic of Korea.

xvii

EXECUTIVE SUMMARY

To assess the reflood model of RELAP5/MOD3.3, simulations of eight FLECHT-SEASET tests 

were conducted. The selected FLECHT-SEASET tests have various initial and boundary 

conditions such as the flooding rate varying from 2.1 to 15.5 cm/s, the upper plenum pressure 

varying from 0.13 to 0.41 MPa, and the coolant temperature varying from 306 to 408 K. A more 

detailed axial noding for the bundle test section was used in this assessment compared to other 

previous ones. Predictions for several significant parameters including peak clad temperatures,

quench times, and heat transfer coefficients at various elevations were compared to the 

measurement data. From the comparison, the following findings were obtained.

● The code predicts the measured peak clad temperatures within ±10% deviation.

● The code predicts rod quenches to occur much earlier than the measurement data.

● The code has a tendency of under-predicting peak vapor temperatures at 2 different 

elevations, especially those of low flooding rate tests.

● The code has a tendency of over-predicting the overall pressure drop for the entire bundle

(or collapsed level in the core).

Based on these findings, the wall-to-fluid heat transfer models which are activated during the 

reflood calculations were modified to improve the code’s predictability mainly for quench times. 

The modifications can be summarized as follows:

● The film boiling heat transfer regime was divided into three different sub-regimes (inverted 

annular film boiling regime, inverted slug film boiling regime, and dispersed flow film boiling 

regime).

● Appropriate heat transfer correlations were selected to predict wall-to-vapor or wall-to-liquid 

heat transfers in each sub-regime.

● Minor coding errors in the subroutines computing the post-CHF droplet diameter and the 

transition boiling heat transfer coefficient, respectively were fixed.

● The radiation heat transfer model was slightly modified to assume more reasonable and 

consistent values for emissivity and droplet diameter.

All the modifications were embodied into a modified version and the same set of eight FLECHTSEASET tests were simulated again with the modified version. From the comparisons of the 

predictions using the modified version to the predictions using the original version as well as the 

measurement data, the following conclusions were derived.

● The RMS error in overall PCT predictions can be reduced from 48.3 to 36.7 K by the 

modifications.

● The RMS error in overall quench time predictions can be reduced from 85.9 to 32.1 

seconds by the modifications.

● The film boiling heat transfer coefficients predicted using the modified version shows better 

agreement with the measurement data compared to those predicted using the original 

version.

● Wall-to-vapor heat transfers are increased by the modifications so that the predicted vapor 
xviii

temperatures are higher than those predicted by the original version.

● Even with the modifications, the code still has a tendency of over-predicting the overall 

pressure drop for the entire core (or collapsed liquid level in the core). Thus, further efforts 

to improve the reflood model of RELAP5/MOD3.3 should be made to the wall or interfacial 

drag models.
xix

ABBREVIATIONS

HTC Heat Transfer Coefficient

KAERI Korea Atomic Energy Research Institute

KEPRI Korea Electric Power Research Institute

KNF Korea Nuclear Fuel

LBLOCA Large Break Loss-Of-Coolant-Accident

PCT Peak Clad Temperature

PWR Pressurized Water Reactor

RMS Root-Mean-Square

USNRC United States Nuclear Regulatory Commission

xxi

NOMENCLAUTURE

f a liquid absorption coefficient

gf a interfacial area per unit volume

CD droplet drag coefficient

Dh hydraulic diameter

d average droplet diameter

dmax maximum droplet diameter defined by Eq.(5)

dWe=1.5 droplet diameter when Weber number = 1.5

dWe=7.5 droplet diameter when Weber number = 7.5

Flt Linear function depending on the gas Reynolds number

Fwf wall-to-liquid grey body factor

fw wall friction factor

Gf liquid mass flux

g gravitational acceleration

hBr HTC calculated with the Bromley correlation

hCT HTC calculated with the CATHARE correlation

Ditt h HTC calculated with a call to the subroutine DITTUS

fg h latent heat of vaporization

hFR HTC calculated with the Forslund-Rohsenow correlation

hlam laminar convective HTC

hmax HTC defined by Eq.(26)

hMBr HTC calculated with the modified Bromley Correlation

htur turbulent convective HTC

wf h wall-to-liquid HTC

wf,DF h wall-to-vapor HTC for the DFFB regime

hwf,IA wall-to-liquid HTC for the IAFB regime

hwg wall-to-vapor HTC

hwg,DF wall-to-vapor HTC for the DFFB regime

hwg,IA wall-to-vapor HTC for the IAFB regime

KBY Reynolds number dependent coefficient defined by Eq.(13)

kg vapor conductivity

P/DR pitch-to-diameter ratio

"

CHF q critical heat flux

R , R , R 123 R terms in radiation heat transfer model used to calculate the grey body factor

Red droplet Reynolds number
xxii

Reg vapor Reynolds number

Tsat saturation temperature

Tw wall temperature

Tw,CHF wall temperature at the CHF point

vg vapor velocity

vr relative velocity

x, y weighting functions defined by Eq.(10)

ZQmin distance from the point in question to the bottom quench front

Greeks

αf liquid volume fraction

αg vapor volume fraction

∆TCHF

difference between the wall temperature at the CHF point and the saturation 

temperature

δ vapor film thickness

f ε liquid emissivity

εw wall emissivity

μg vapor viscosity

f ρ liquid density

ρg vapor density

σ surface tension

i τ friction force per unit volume due to interfacial drag

τw fiction force per unit volume due to wall drag

Φ2p two-phase enhancement factor

Φtur turbulent flow multiplier for a vertical bundle geometry

Subscripts

IA inverted annular film boiling

DF dispersed flow film boiling

f liquid

g vapor

wf wall-to-liquid

wg wall-to-vapor

sat saturation

lam laminar

tur turbulent
1

1. INTRODUCTION

In the analyses of a Pressurized Water Reactor (PWR) Large Break Loss-Of-Coolant Accident

(LBLOCA), one of the most important tasks is to predict accurately the thermal-hydraulic 

phenomena occurring in the core during the reflood phase. This phase typically starts with a 

nearly empty core under adiabatic conditions. Subcooled water is then injected from the bottom 

of core. The injected water interacts with hot fuel rods and produces large amounts of steam 

which binds the flooding rate via increasing upper plenum pressure. During the phase, various 

heat transfer regimes (or modes) such as single-phase vapor convection, nucleate boiling, 

transition boiling, film boiling, and single-phase liquid convection exist in the core, sometimes all 

at once. 

To accurately predict complicated thermal-hydraulic phenomena in the core during reflood, 

RELAP5/MOD3.3 (patch 03) has a special heat transfer package that is activated during that 

phase only. Most of this package had been originally developed by Analytis [1] and was slightly 

modified in its official release.

Few activities, with the exception of developmental assessment by Analytis, have been made to 

assess the reflood model of RELAP5/MOD3.3. To the best of our knowledge, the most recent 

assessment of RELAP5 reflood model was conducted by Koszela [2] using an interim version 

(RELAP5/MOD3.2.2 Gamma). He simulated the ABB Atom 3×3-Rod Bundle Reflooding Tests 

using the default model options and concluded that the code still had several deficiencies in the 

reflood model. In his work, the cladding temperature peaks and final quenches were predicted 

to occur too early.

One of the purposes of this report is to assess the RELAP5/MOD3.3 reflood model using 

selected FLECHT-SEASET tests. Compared to previous similar assessments [3], [4], a more 

detailed axial noding for the bundle test section and more accurate initial and boundary 

conditions were used in this assessment.

Based on our assessment, we carefully reviewed and modified the wall-to-fluid heat transfer 

models. Note that these modifications introduced nearly no new heat transfer correlations. The 

correlations used in the original version were restructured to result in better predictions.

To investigate the effect of our modifications, assessment calculations were conducted again 

using the modified version against the same set of FLECHT-SEASET tests. Various significant 

parameters including peak clad temperatures (PCTs), quench times, and heat transfer 

coefficients (HTCs) were compared to both values predicted using the original version and 

measurements.

The assessment of the original RELAP5/MOD3.3 reflood model against eight FLECHT-SEASET 

tests is described in Chapter 2. A brief description for the FLECHT-SESET facility and the 

selected tests is also made in this chapter. Chapter 3 describes the reflood model of 

RELAP5/MOD3.3 briefly and explains how we modified the code to improve the wall-to-fluid 

heat transfer models. The effect of code modifications is also analyzed in this Chapter. Final 

conclusions of this study are presented in Chapter 4.
2
3

2. ASSESSMENT OF ORIGINAL REFLOOD MODEL

2.1 FLECHT-SEASET Tests

The FLECHT-SEASET tests have been regarded as representative reflood experiments 

because the test facility was large and relatively well instrumented. The test facility was 

constructed by modifying the FLECHT facility mainly to accept a new heater rod bundle of which 

dimensions were typical of the Westinghouse 17x17 fuel bundle. It consisted of a cylindrical test 

section, a coolant accumulator, an entrained liquid separation tank, an external pipe downcomer 

for the gravity reflood tests, a steam boiler for back-pressure regulation, and the required piping 

and valves. As the facility is described in detail in a FLECHT-SEASET data report [5], only the 

major components are briefed here. The overall facility layout is presented in Figure 1.

A cylindrical test section was composed of a lower plenum, a low mass housing, and an upper 

plenum. The low-mass housing contained the heater rod bundle consisting of 161 heater rods 

and 16 thimble rods which were placed with a square lattice array similar to the 17x17 

Westinghouse fuel bundle design. It was a cylindrical vessel with a 19.37 cm (7.625 in) inside 

diameter by 0.477 cm (0.188 in) wall, constructed of SA-312, type 304 stainless steel. The 

minimum wall thickness was chosen so that the housing would absorb or release the minimum 

amount of heat to the rod bundle. The length of the heated part was 3.66 m (12 ft).

The cross-sectional view of the heater rod bundle is shown in Figure 2 with the corresponding 

instrumentation groups. The bundle comprised 161 heater rods (68 instrumented), 4 

instrumented thimbles, 12 steam probes, 8 solid triangular fillers, and 8 spacer grids. A Kanthal 

heater coil imbedded in boron nitride was used to heat the rods which had stainless steel 

cladding. The outside diameter and the wall thickness of the heater rod were 9.5 mm (0.374 in) 

and 0.64 mm (0.025 in), respectively. Rod clad temperatures were measured by Type K 

thermocouples which were welded at the inner surface of the stainless steel cladding. The rodto-rod pitch was 12.6 mm (0.496 in) and each rod had a cosine axial power profile shown in 

Figure 3. The triangular fillers were welded to the grids to maintain the proper grid locations. The 

fillers served also to reduce the amount of excess flow area.

The low mass housing was joined to the upper and lower plenums by flange connections. There 

were an upper and a lower extension in the upper and lower plenums. The entrained liquid 

collected in the upper plenum was prevented from falling back into the bundle by the upper 

extension. The lower extension had a role of distributing the injected coolant uniformly. 

After passing through the upper plenum baffle pipe which helped improve liquid carryout 

separation, the exhaust vapor was directed to the entrainment separator through the exhaust 

line piping. The entrainment separator was a standard liquid-vapor separator having a large 

volume to minimize the housing pressure oscillations. 

Before a test was conducted, auxiliary components such as the carryover vessel, entrainment 

separator, separator drain tank, test section upper plenum, and test section outlet piping were 

heated to slightly above the saturation temperature by clamp-on strip heaters. The test section, 

carryover vessel, and exhaust line components were pressurized to the desired pressure by a 

steam boiler. When the coolant supplied by the gas-pressurized accumulator reached the 

bottom of the heated part of the heater rod bundle, it was circulated to assure the water in the 

lower plenum were at the specified temperature. Power was then supplied to the test bundle 
4

and the rods were heated up. When the bundle temperature from any two designated 

thermocouples reached the preset value, flooding and power decay were initiated automatically.

The instrumentation of the FLECHT-SEASET facility was quite extensive, including 205 heater 

rod thermocouples, 12 differential pressure cells positioned 0.3048 m (1 ft) apart along the axial 

direction of the heated section, 12 steam probes, and inlet and outlet flow meters.

Among the numerous tests performed at the FLECHT-SEASET test facility, 8 forced reflood 

tests were selected for RELAP5/MOD3.3 assessment. Their test conditions are presented in 

Table 1. These tests were also used for the assessment of TRACE [6]. Flooding rates varied 

from 2.1 to 15.5 cm/s (0.81 to 6.10 in/sec) with the upper plenum pressure varying from 0.13 to 

0.41 MPa (19 to 60 psia) and the coolant temperature varying from 306 to 408 K (91 to 257 °F). 

All 8 tests had the same initial rod power of 2.3 kW/m (0.7 kW/ft) at the peak location and they 

had a uniform radial power distribution. Note that the test conditions listed in Table 1 are 

nominal values and the actual values varied to some extent with time.

2.2 RELAP5 Model

For the RELAP5 simulations, only the bundle test section was modeled in a detailed manner. 

Other parts of the test facility, such as the coolant injection system and the bundle flow exhaust 

system, were greatly simplified. The facility was represented by four fluid components (Figure 4). 

Two time-dependent volume (TMDPVOL) components represent the coolant injection system 

and the flow exhaust system. One single-volume (SNGLVOL) component represents the inlet 

pipe and one pipe (PIPE) component does the heated section of the cylindrical housing. The 

heated section was modeled using 49 equal length (7.62 cm (3.0 in)) axial nodes. Note that the 

top and bottom elevations of the PIPE component were extended to 3.81 cm (1.5 in) above and 

below the heated section to make the center of the first and last nodes meet with the 

measurement locations. With this noding, it was possible to give the form losses at the spacer 

grids to the locations close to the real bottom elevations of spacer grids. It was also possible to 

obtain the heater rod clad temperatures at the exact locations of measurement. The form losses 

at the spacer grids were modeled by specifying the pressure loss coefficient to 1.20. The same 

loss coefficient was used also in the assessment of TRACE [6].

Five heat structures were located in the PIPE component to model the active heater rods, the 

housing wall, the thimbles, the filler rods, and the failed heater rods. The number of failed heater 

rods was 4 for Test 31302 and 2 for the others. The length of the first and last axial nodes is one 

half of other ones so that the center of all other axial nodes matched with the center of the 

hydraulic nodes in the PIPE component. Heater rods were divided into 7 radial nodes to model 

the Kanthal heater coil insulated with boron nitride that is encased with stainless steel cladding. 

The electrical power was provided as a time-dependent table. The coolant inlet velocity as a 

function of time was given to a time-dependent junction (TMDPJUN) component. The inlet 

coolant temperature and the upper plenum pressure were given to the TMDPVOL components 

representing the coolant injection system and the flow exhaust system, respectively. The initial 

temperatures of heater rods and the housing wall at various axial locations were determined 

from a linear interpolation of measurement data. The initial temperature of the failed rods and 

fillers were assumed to be equal to that of the housing wall.

The calculations were initiated at the time of flooding. The user’s guidelines in [7] were followed 

tightly to select appropriate inputs for the time step control, the volume-related options, and 

junction-related options. The maximum time step was set to 0.1 s in all calculations though the 
5

time step was reduced automatically to satisfy the Courant limit or avoid water property failures. 

We believe the modeling approach described above has several arguable features that should 

be discussed more.

First, compared to other previous FLECHT-SEASET calculations, a more detailed axial noding 

for the bundle test section was used in this study. At first, we tried to use 20 equal length nodes 

for the test section just like other previous assessments [3], [4], but the predicted bottom quench 

front in that case showed stepwise increases during the entire transient (Figure 5). In addition, 

with 20 equal length nodes, we can not compare predicted temperatures directly to 

measurements directly, as mentioned earlier.

Second, the entire test section was modeled as a single channel. Even though the tests we 

selected for this assessment had a uniform radial power distribution, the clad temperature 

measurements at an elevation have some distribution. Per Westinghouse [8], the distribution 

can be attributed to the individual heater rod resistance differences, manufacturing tolerances 

on materials, dimension variations, initial temperature differences, the radial location of a heater 

rod relative to the unheated guide thimbles, and sub-channel-to-sub-channel flow variations. It is 

nearly impossible to correctly take all these factors into account in a RELAP5 calculation 

because the code is basically a one-dimensional code. Certainly, some previous RELAP5 

calculations used a two channel modeling for the test section, but we believe it may introduce 

another kind of uncertainties related to the use of cross-flow junctions. A single channel 

modeling for the test section has an effect of averaging the radial distribution of clad 

temperatures. Thus, the arithmetic average values of measured PCTs and quench times were 

used in the quantitative comparison to predictions in this study.

Third, we did not take into account the radiation heat transfer between the housing wall and 

peripheral rods. According to Westinghouse [8], the radiation heat transfer from the housing can 

be restricted to the outer-most rods. Thus, no readings from those thermocouples located in the 

outer-most row of rods were used in the quantitative comparison to predictions.

Appendix to this report presents the input deck for Test 31805 and only the inputs for test 

specific initial and boundary conditions can vary test by test.

2.3 Assessment Results

FLECHT-SEASET test simulations using RELAP5/MOD3.3 (patch 03) were started at the time 

of reflood corresponding to the initial injection of cold water into the test section. To assess the 

predictive capability of the code, detailed comparisons between measurement data and 

RELAP5 calculations were made for each test. The compared parameters are as follows:

● Heater rod clad temperatures at 8 different elevations; 0.610 m (2 ft), 1.219 m (4 ft), 1.829

m (6 ft), 1.981 m (6.5 ft), 2.438 m (8 ft), 3.048 m (10 ft), 3.353 m (11 ft), and 3.505 m (11.5 ft)

● Vapor temperatures at 1.829 m (6 ft) and 3.048 m (10 ft) elevations

● Quench front elevation as a function of time

● Differential pressure for the entire 3.658 m (12 ft) core

● Differential pressure between 1.829 m (6 ft) and 2.134 m (7 ft) elevations

● Differential pressure between 3.048 m (10 ft) and 3.353 m (11 ft) elevations

● HTCs at 5 different elevations; 1.219 m (4 ft), 1.829 m (6 ft), 1.981 m (6.5 ft), 2.438 m (8 ft),

and 3.048 m 
6

 

FLECHT-SEASET had more than one rod temperature measurements at an elevation. For 

example, at 1.8 m (6 ft) elevation, there existed 21 thermocouples for the rod clad temperatures. 

In the comparison to the predicted one, all the valid measurement data were used.

Not only the measured but also the predicted quench front elevation was evaluated from the 

heater rod clad temperatures. If the rod clad temperature drop during a time step (or the 

measurement interval) at an elevation was lower than a specified value, the elevation was 

regarded as quenched. In other words, the rod clad temperature should satisfy the following 

relation at the quench time.

t+3Δt t+2 Δt

t=Quench Time t+3Δt t+2 Δt

dT T - T

 = -X

dt t - t

⋅ ⋅

⋅ ⋅

〈 (1)

where T and t are the rod clad temperature and time, respectively and Δt is the time step 

or the measurement interval. For X , 27.8 K/s (50 °F/sec) was tried first, but in a few cases 

having a very gradual temperature decrease, 16.7 K/s (30 °F/sec) was used also. The 

measured quench time at an elevation was obtained by averaging the quench times which were 

determined using all the valid thermocouple readings at that elevation. 

Both the measured and the predicted HTCs are defined as the heat flux divided by the 

difference between the clad and the saturation temperatures. The measured HTCs were already 

derived by the USNRC [6]. They used a program called IHCP1D with the 9 second average 

option to remove high oscillations. For consistency, the same time averaging process was also 

applied to get the predicted HTCs. For the measured HTCs, three HTCs (minimum, maximum, 

and average) derived from multiple rod clad temperature measurements are presented. The 

average one was computed as the arithmetic average of HTCs from all instrumented rods 

having valid clad temperature measurements at a given elevation.

Comparisons of predicted results to the measurement data are made in Figure 6 through Figure 

157. The figures contain also the results using a modified version, but only the results with the 

original version are discussed in this chapter. The results with a modified version will be 

discussed in Chapter 3 emphasizing the effect of modifications.

2.3.1 Test 31805

Test 31805 was a 2.1 cm/s (0.81 in/sec) reflood test at 0.28 MPa (40 psia). Inlet liquid 

temperature was 324 K (124 °F). Of all the tests simulated in this study, this test had the lowest 

flooding rate.

Heater rod clad temperatures predicted by RELAP5 at various elevations are compared to the 

measured data in Figure 6 through Figure 13. The maximum predicted PCT is 1359 K at 1.981 

m (6.5 ft) elevation while the measured PCTs at the same elevation are in the range of 

1353~1509 K. Though the prediction locates between the maximum and minimum measured 

values, the code is believed to under-predict the PCT because the prediction is 92 K lower than 

the arithmetic average of measurements. The tendency of under-predicting PCTs becomes 

stronger at higher elevations. The predicted PCTs at 2.438 m (8 ft), 3.048 m (10 ft), and 3.353 m 

(11 ft) elevations are even lower than the lowest measured PCT at each elevation. The percent 

differences between the predicted PCTs and the measurements at 3.353 m (11 ft) and 3.505 m 

(11.5 ft) elevations are smaller than those at 2.438 m (8 ft) or 3.048 m (10 ft) elevations. 
7

Vapor temperatures predicted are compared to the measured data in Figure 14 and Figure 15. 

The vapor temperature at 1.829 m (6 ft) was under-predicted much compared to the 

measurements. The rapid increase before ~30 seconds and the re-heating after ~60 seconds 

were not simulated well. The predicted vapor temperature at 3.048 m (10 ft) increased too fast 

as soon as the transient began and the peak temperature was predicted to occur too early.

The predicted and measured quench fronts are compared in Figure 16. The final quenches were 

predicted to occur much earlier than the measurements at all elevations except a bottom region 

(at and below 1.219 m (4 ft)). The difference between the predicted quench time and the 

arithmetic average of measured quench times (predicted – measured) varies from -177 to -7

seconds and the maximum absolute deviation occurred at 3.505 m (11.5 ft).

The predicted and measured differential pressures for the entire core region, a mid-level (1.829

to 2.134 m (6 to 7 ft)), and a top region (3.048 to 3.353 m (10 to 11 ft)) are compared in Figure 

17, Figure 18, and Figure 19, respectively. The predicted value for the entire core is higher than 

the measurement data from the beginning of transient and the deviation is about 2~3 kPa 

(0.29~0.44 psi) after ~100 seconds. It means that the lower part of the test section was filled up 

with liquid too fast and the difference of collapsed liquid level was maintained until the end of 

transient as the differential pressure is essentially equivalent to the hydrostatic head. The 

predicted differential pressure for the mid-level becomes higher than the measurement at ~250 

seconds. For the top region, the differential pressure was predicted relatively well until a 

quantitative comparison becomes doubtful due to large oscillations in the prediction.

The predicted and measured HTCs at five different elevations are compared in Figure 20

through Figure 24. Excluding the early steam cooling only period, the HTCs at all elevations

were significantly over-predicted until the quench time. Generally speaking, the reflood HTCs 

increases abruptly as the transition boiling regime begins. Thus, the figures indicate that the 

code over-predicted much the HTCs in the film boiling regime.

2.3.2 Test 31504

Test 31504 was a 2.4 cm/s (0.97 in/sec) reflood test at 0.28 MPa (40 psia). Inlet liquid 

temperature was 324 K (124 °F). The test had very similar initial and boundary conditions to 

those of Test 31805 but the flooding rate was slightly higher than that of Test 31805. 

Heater rod clad temperatures predicted by RELAP5 at various elevations are compared to the 

measured data in Figure 25 through Figure 32. The maximum PCT predicted by the code is 

1319 K at 1.981 m (6.5 ft) elevation while the measured PCTs at the same elevation are in the 

range of 1322-1423 K. The predicted maximum PCT is 42 K lower than the arithmetic average 

of measurements. The tendency of under-predicting PCTs becomes stronger at higher 

elevations. The predicted PCTs at 1.981 m (6.5 ft), 2.438 m (8 ft), and 3.048 m (10 ft) elevations 

are even lower than the lowest measured PCT at each elevation. The percent differences 

between the predicted PCTs and the measurements at 3.353 m (11 ft) and 3.505 m (11.5 ft) 

elevations are much smaller than at 2.438 m (8 ft) or 3.048 m (10 ft) elevations. 

Vapor temperatures predicted are compared to the measured data in Figure 33 and Figure 34. 

The vapor temperature at 1.829 m (6 ft) was under-predicted much compared to the 

measurements. The rapid increase before ~20 seconds and the re-heating after ~50 seconds 

were not simulated well. The predicted vapor temperature at 3.048 m (10 ft) increased too fast 

as soon as the transient began and the peak temperature was predicted to occur too early.
8

The predicted and measured quench fronts are compared in Figure 35. The final quenches were 

predicted to occur much earlier than the measurements at all elevations except a bottom region 

(at and below 1.219 m (4 ft)). The difference between the predicted quench time and the 

arithmetic average of measured quench times (predicted – measured) varies from -149 to -5 

seconds and the maximum absolute deviation occurred at 3.353 m (11 ft).

The predicted and measured differential pressures for the entire core region, a mid-level (1.829 

to 2.134 m (6 to 7 ft)), and a top region (3.048 to 3.353 m (10 to 11 ft)) are compared in Figure 

36, Figure 37, and Figure 38, respectively. The predicted value for the entire core is higher than 

the measurement data from the beginning of transient and the deviation is about 4~5 kPa 

(0.58~0.73 psi) after ~60 seconds. It means that the lower part of the test section was filled up 

with liquid too fast and the difference of collapsed liquid level was maintained until the end of 

transient. The predicted differential pressure for the mid-level becomes higher than the 

measurement after ~200 seconds. For the top region, the differential pressure was overpredicted early in the transient, but the deviation does not look large.

The predicted and measured HTCs at five different elevations are compared in Figure 39 

through Figure 43. Excluding the early steam cooling only period, the HTCs at all elevations

were significantly over-predicted until the quench time, which means that the code overpredicted much the HTCs in the film boiling regime.

2.3.3 Test 31203

Test 31203 was a 3.8 cm/s (1.51 in/sec) reflood test at 0.28 MPa (40 psia). Inlet liquid 

temperature was 52 K (126 °F). The test has very similar initial and boundary conditions to 

those of Test 31805 or Test 31504 but the flooding rate was a little higher than that of Test 

31504.

Heater rod clad temperatures predicted by RELAP5 at various elevations are compared to the 

measured data in Figure 44 through Figure 51. The maximum PCT predicted by the code is 

1224 K at 1.829 m (6.0 ft) elevation while the measured PCTs at the same elevation are in the 

range of 1206-1297 K. Note that the highest average of the measured PCTs was obtained at 

1.981 m (6.5 ft) elevation. The predicted maximum PCT is 45 K lower than the arithmetic 

average of measurements at that elevation. The predicted PCTs at 1.981 m (6.5 ft) and 2.438 m 

(8 ft) are even lower than the lowest measured PCT at each elevation. On the contrary, the 

predicted PCTs at 3.353 m (11 ft) and 3.505 m (11.5 ft) are higher than the arithmetic average of 

measurements at each elevation.

Vapor temperatures predicted are compared to the measured data in Figure 52 and Figure 53. 

The vapor temperature at 1.829 m (6 ft) was under-predicted much compared to the 

measurements. The rapid increase before ~10 seconds and the re-heating after ~30 seconds 

were not simulated well. The predicted vapor temperature at 3.048 m (10 ft) increased too fast 

as soon as the transient began and the peak temperature was predicted to occur too early. 

The predicted and measured quench fronts are compared in Figure 54. The final quenches were 

predicted to occur much earlier than the measurements at all elevations except the lowest 

elevation (0.610 m (2 ft)). The difference between the predicted quench time and the arithmetic 

average of measured quench times (predicted – measured) varies from -148 to -6 seconds and 

the maximum absolute deviation occurred at 3.048 m (10 ft).
9

The predicted and measured differential pressures for the entire core region, a mid-level (1.829 

to 2.134 m (6 to 7 ft)), and a top region (3.048 to 3.353 m (10 to 11 ft)) are compared in Figure 

55, Figure 56, and Figure 57, respectively. The predicted value for the entire core is about 3~4

kPa (0.44~0.58 psi) higher than the data after ~20 seconds. The predicted differential pressure 

for the mid-level becomes higher than the measurement after ~130 seconds. For the top region, 

the differential pressure was over-predicted early in the transient. 

The predicted and measured HTCs at five different elevations are compared in Figure 58 

through Figure 62. Excluding the early steam cooling only period, the HTCs at all elevations

were significantly over-predicted until the quench time, which means that the code overpredicted much the HTCs in the film boiling regime.

2.3.4 Test 31302

Test 31302 was a 7.7 cm/s (3.01 in/sec) reflood test at 0.28 MPa (40 psia). Inlet liquid 

temperature was 325 K (126 °F). The test has very similar initial and boundary conditions to 

those of Test 31203 but the flooding rate was about two times higher than that of Test 31203. 

Heater rod clad temperatures predicted by RELAP5 at various elevations are compared to the 

measured data in Figure 63 through Figure 70. The maximum PCT predicted by the code is 

1159 K at 1.829 m (6.0 ft) elevation while the measured PCTs at the same elevation are in the 

range of 1120~1191 K. The predicted maximum PCT is only 2 K lower than the arithmetic 

average of measurements at the same elevation. Only the PCTs at 3.353 m (11 ft) were

definitely over-predicted. 

Vapor temperatures predicted are compared to the measured data in Figure 71 and Figure 72. 

The vapor temperature at 1.829 m (6 ft) was predicted relatively well though the maximum 

temperature occurred a little earlier than the measurements. The vapor temperatures at 3.048 m 

(10 ft) were 100~200 K over-predicted.

The predicted and measured quench fronts are compared in Figure 73. The final quenches were 

predicted to occur much earlier than the measurements at all elevations. The difference 

between the predicted quench time and the arithmetic average of measured quench times 

(predicted – measured) varies from -120 to -7 seconds and the maximum absolute deviation 

occurred at 3.048 m (10 ft).

The predicted and measured differential pressures for the entire core region, a mid-level (1.829 

to 2.134 m (6 to 7 ft)), and a top region (3.048 to 3.353 m (10 to 11 ft)) are compared in Figure 

74, Figure 75, and Figure 76, respectively. The differential pressure for the entire core region 

was predicted relatively well before ~100 seconds, but it was over-predicted by 2~4 kPa 

(0.29~0.58 psi) after that time. The predicted differential pressure for the mid-level becomes 

higher than the measurement after ~70 seconds. For the top region, the predicted differential 

pressure looks higher than the measurement after ~120 seconds when the prediction starts to 

oscillate severely. The times when the predicted differential pressures for the mid-level and a 

top region become higher than the measurements are close to the times when the predicted rod 

clad temperatures at those elevations start to drop fast (Figure 65 and Figure 68). Thus, we 

believe the over-predicted differential pressure (or collapsed liquid level) is one of the reasons 

why the quench times of this test were predicted to occur much earlier than the experiment.

The predicted and measured HTCs at five different elevations are compared in Figure 77 

through Figure 81. The HTCs in the film boiling regime were a little over-predicted at all 
10

elevations, but the deviations are not as large as in the cases of lower flooding rate tests (Test 

31805, Test 31504, and Test 31203).

2.3.5 Test 31701

Test 31701 was a 15.5 cm/s (6.10 in/sec) reflood test at 0.28 MPa (40 psia). Inlet liquid 

temperature was 326 K (127 °F). Of all the tests simulated in this study, this test had the highest 

flooding rate. 

Heater rod clad temperatures predicted by RELAP5 at various elevations are compared to the 

measured data in Figure 82 through Figure 89. The maximum PCT predicted by the code is 

1135 K at 1.829 m (6.0 ft) elevation while the measured PCTs at the same elevation are in the 

range of 1114~1175 K. The predicted maximum PCT is 17 K lower than the arithmetic average 

of measurements at the same elevation. Just like Test 31302, the PCT predictions are relatively 

excellent compared to lower flooding rate tests (Test 31805, 31504, and 31203). 

Vapor temperatures predicted are compared to the measured data in Figure 90 and Figure 91. 

The vapor temperature at 1.829 m (6 ft) was predicted relatively well though the heat up early in 

the transient was predicted to stop a few seconds earlier than the measurements. The vapor 

temperature at 3.048 m (10 ft) was over-predicted by 50~150 K. 

The predicted and measured quench fronts are compared in Figure 92. The final quenches were 

predicted to occur a little earlier than the measurements at all elevations. The difference 

between the predicted quench time and the arithmetic average of measured quench times 

(predicted – measured) varies from -41 to -3 seconds and the maximum absolute deviation 

occurred at 3.048 m (10 ft). Note that the measured quench times show a wide distribution in a 

top region at and above 3.048 m (10 ft).

The predicted and measured differential pressures for the entire core region, a mid-level (1.829 

to 2.134 m (6 to 7 ft)), and a top region (3.048 to 3.353 m (10 to 11 ft)) are compared in Figure 

93, Figure 94, and Figure 95, respectively. The predicted value for the entire core is higher than 

the measurement data from the beginning of transient and the deviation is about 3~5 kPa 

(0.44~0.73 psi) after ~10 seconds. The predicted differential pressure for the mid-level becomes 

higher than the measurement after ~25 seconds. The top region was also predicted to be filled 

with liquid earlier than the measurement. 

The predicted and measured HTCs at five different elevations are compared in Figure 96 

through Figure 100. The code tends to over-predict the HTCs, especially in a lower part of the 

core. We believe that the rapid filling of the core with liquid, which is observed in Figure 93, 

Figure 94, or Figure 95, is one of the main reasons for the over-prediction of HTCs.

2.3.6 Test 31108

Test 31108 was a 7.9 cm/s (3.11 in/sec) reflood test at 0.13 MPa (40 psia). Inlet liquid 

temperature was 306 K (91 °F). The test has similar initial and boundary conditions to those of 

Test 31302 but the upper plenum pressure is about one half of that of Test 31302.

Heater rod clad temperatures predicted by RELAP5 at various elevations are compared to the 

measured data in Figure 101 through Figure 108. The maximum PCT predicted by the code is 

1145 K at 1.829 m (6.0 ft) elevation while the measured PCTs at the same elevation are in the 

range of 1126~1200 K. The predicted maximum PCT is 23 K lower than the arithmetic average 
11

of measurements at the same elevation. The predicted PCTs are slightly lower than the 

arithmetic average of measurements at all elevations except 3.048 m (10 ft) and 3.353 m (11 ft) 

where PCTs were definitely over-predicted.

Vapor temperatures predicted are compared to the measured data in Figure 109 and Figure 

110. The vapor temperature at 1.829 m (6 ft) was predicted relatively well though the maximum 

temperature occurred a little earlier than the measurements. The vapor temperatures at 3.048 m 

(10 ft) were 100~200 K over-predicted.

The predicted and measured quench fronts are compared in Figure 111. The final quenches 

were predicted to occur much earlier than the measurements at all elevations except 3.505 m 

(11.5 ft) elevation. The difference between the predicted quench time and the arithmetic average 

of measured quench times (predicted – measured) varies from -162 to +13 seconds and the 

maximum absolute deviation occurred at 3.048 m (10 ft).

The predicted and measured differential pressures for the entire core region, a mid-level (1.829 

to 2.134 m (6 to 7 ft)), and a top region (3.048 to 3.353 m (10 to 11 ft)) are compared in Figure 

112, Figure 113, and Figure 114, respectively. The differential pressure for the entire core region 

is higher than the measurement data from the beginning of transient and the deviation is 3~7

kPa (0.44~1.02 psi) after ~10 seconds. The predicted differential pressure for the mid-level 

becomes higher than the measurement after ~90 seconds. For the top region, the predicted 

differential pressure is maintained a little higher than the measurement for ~150 seconds and 

oscillates highly after that time. The times when the predicted differential pressures for the midlevel and the top region become higher than the measurements are close to the times when the 

predicted rod clad temperatures at those elevations start to drop fast (Figure 103 and Figure 

106). Thus, we believe the over-predicted differential pressure (or collapsed liquid level) is one 

of the reasons why the quench times of this test were predicted to occur much earlier than the 

experiment.

The predicted and measured HTCs at five different elevations are compared in Figure 115 

through Figure 119. The film boiling HTCs were a little over-predicted in a lower part of the core 

while they were a little under-predicted in a top region. 

2.3.7 Test 32013

Test 32013 was a 2.6 cm/s (1.04 in/sec) reflood test at 0.41 MPa (60 psia). Inlet liquid 

temperature was 339 K (150 °F). The test has similar initial and boundary conditions to those of 

Test 31504 but the upper plenum pressure is 0.14 MPa (20 psi) higher that of Test 31504.

Heater rod clad temperatures predicted by RELAP5 at various elevations are compared to the 

measured data in Figure 120 through Figure 127. The maximum PCT predicted by the code is 

1326 K at 1.981 m (6.5 ft) elevation while the measured PCTs at the same elevation are in the 

range of 1306~1431 K. The predicted maximum PCT is 55 K lower than the arithmetic average 

of measurements. The tendency of under-predicting PCTs becomes stronger at higher 

elevations. The predicted PCTs at 2.438 m (8 ft) and 3.048 m (10 ft) elevations are even lower 

than the lowest measured PCT at each elevation. The percent differences between the 

predicted PCTs and the measurements at 3.353 m (11 ft) and 3.505 m (11.5 ft) elevations are 

smaller than at 2.438 m (8 ft) and 3.048 m (10 ft) elevations.

Vapor temperatures predicted are compared to the measured data in Figure 128 and Figure 

129. The vapor temperature at 1.829 m (6 ft) was under-predicted much compared to the 
12

measurements. The rapid increase before ~20 seconds and the re-heating after ~50 seconds 

were not simulated well. The predicted vapor temperature at 3.048 m (10 ft) increased too fast

as soon as the transient began and the peak temperature was predicted to occur too early. 

The predicted and measured quench fronts are compared in Figure 130. The final quenches 

were predicted to occur much earlier than the measurements at all elevations except a bottom 

region (at and below 1.219 m (4 ft)). The difference between the predicted quench time and the 

arithmetic average of measured quench times (predicted – measured) varies from -101 to -2 

seconds and the maximum absolute deviation occurred at 3.505 m (11.5 ft).

The predicted and measured differential pressures for the entire core region, a mid-level (1.829 

to 2.134 m (6 to 7 ft)), and a top region (3.048 to 3.353 m (10 to 11 ft)) are compared in Figure 

131, Figure 132, and Figure 133, respectively. The predicted value for the entire core was 

predicted quite well. However, the predicted differential pressure for the mid-level becomes 

higher than the measurement after ~180 seconds. For the top region, the differential pressure 

was over-predicted early in the transient, but the difference does not look large.

The predicted and measured HTCs at five different elevations are compared in Figure 134 

through Figure 138. Excluding the early steam cooling only period, the HTCs at all elevations 

were over-predicted much until the quench time, which means that the code over-predicted the 

HTCs in the film boiling regime.

2.3.8 Test 32114

Test 32114 was a 2.5~3.1 cm/s (1.00~1.22 in/sec) reflood test at 0.28 MPa (40 psia). Inlet liquid 

temperature was 408 K (257 °F). Of all the tests simulated in this study, this test had the 

smallest inlet subcooling of 5 K (10 °F). Other seven tests had similar inlet subcooling of 74~79 

K (134~143 °F).

Heater rod clad temperatures predicted by RELAP5 at various elevations are compared to the 

measured data in Figure 139 through Figure 146. The maximum PCT predicted by the code is 

1320 K at 1.981 m (6.5 ft) elevation while the measured PCTs at the same elevation are in the 

range of 1292~1443 K. The predicted maximum PCT is 67 K lower than the arithmetic average 

of measurements. Compared to the arithmetic average of measurement at each elevation, The 

PCTs at 0.610~3.048 m (2~10 ft) were under-predicted while those at higher elevations were 

over-predicted.

Vapor temperatures predicted are compared to the measured data in Figure 147 and Figure 

148. The vapor temperature at 1.829 m (6 ft) was significantly under-predicted compared to the 

measurements. The predicted vapor temperature at 3.048 m (10 ft) increased too fast while the 

peak temperature predicted is not much different from the measured values.

The predicted and measured quench fronts are compared in Figure 149. The final quenches 

were predicted to occur much earlier than the measurements at all elevations, even at the 

elevations where PCTs were over-predicted. The difference between the predicted quench time 

and the arithmetic average of measured quench times (predicted – measured) varies from -113 

to -15 seconds and the maximum absolute deviation occurred at 1.981 m (6.5 ft).

The predicted and measured differential pressures for the entire core region, a mid-level (1.829 

to 2.134 m (6 to 7 ft)), and a top region (3.048 to 3.353 m (10 to 11 ft)) are compared in Figure 

150, Figure 151, and Figure 152, respectively. The predicted value for the entire core is higher 
13

than the measurement from the beginning of transient and the deviation is 3~4 kPa (0.44~0.58 

psi) after ~40 seconds. The predicted differential pressures for the mid-level and top region were 

predicted relatively well until large oscillations were observed. 

The predicted and measured HTCs at five different elevations are compared in Figure 153 

through Figure 157. Excluding the early steam cooling only period, the film boiling HTCs at all 

elevations were over-predicted.

2.3.9 All 8 Tests

The percent deviation between RELAP5/MOD3.3 predicted PCTs and measurements at 8 

different elevations are compared for all 8 tests in Figure 158. As shown in the figure, 

RELAP5/MOD3.3 predicted the measured PCTs within ±10% deviation. The code was well able 

to predict PCTs at lower elevations (up to 1.219 m (4 ft)) while it under-predicted those at middle 

elevations (1.829~2.438 m (6~8 ft)). The PCTs were less under-predicted at upper elevations at 

or above 3.048 m (10 ft), and even over-predicted for a few tests. This is understandable 

because RELAP5 does not have a spacer grid model. In other words, the under-prediction of 

PCTs at higher elevations was compensated to some extent by the lack of a spacer grid model. 

The under-prediction of PCTs at middle elevations was more severe for the tests having 

relatively lower flooding rates (≤ 3.8 cm/s (1.51 in/sec)) and less severe for the tests having 

higher flooding rates (≥ 7.7 cm/s (3.01 in/sec)). The predictive capability did not show any 

consistent or significant variance depending on other test conditions such as upper plenum 

pressure or coolant inlet subcooling. The RMS error in PCT predictions corresponding to Figure 

158 is 48.3 K.

The code under-predicted the peak vapor temperatures at 1.829 m (6 ft) for most tests. The 

code over-predicted the peak vapor temperature at this elevation for only two tests (Test 31302 

and Test 31108) which had flooding rates of 7.7 cm/s (3.01 in/sec) and 7.9 cm/s (3.11 in/sec), 

respectively. The largest deviation was 186 K under-prediction in Test 31504. The code had a 

tendency of under-predicting the peak vapor temperature at 3.048 m (10 ft) for the test having 

relatively lower flooding rates (Test 31805, 31504, 32013, and 32114), but the code overpredicted it for the tests having higher flooding rates (Test 31302, Test 31701, and Test 31108). 

The largest deviation was 165 K over-prediction for Test 31108. Note that this quantitative 

analysis for the vapor temperature predictions can not be regarded as sufficiently accurate since 

there only a few measurements are available at a specified elevation. 

Though the code predicted PCTs relatively well, it could not do quench times. The differences 

between the predicted and measured quench times at 8 different elevations are compared for all 

8 tests in Figure 159. As shown in the figure, rod quenches were predicted to occur too early for 

almost all elevations. In most tests, the differences between the predicted and measured 

quench times increased with elevations, reaching their maximum at around 3.048 m (10 ft) 

elevation. The differences were smaller in a test having a higher flooding rate, but we should 

also consider that the differences may be bigger when the real quench times are longer. 

Comparing Test 31108 to Test 31302 or Test 32013 to Test 31504, it can be seen that the code 

tends to predict better the quench times of a test having a higher upper plenum pressure. No 

clear conclusions can be made for the effect of inlet subcooling on the predictive capability for 

quench times. The RMS error in quench time predictions deduced from Figure 159 is 85.9 

seconds.

The code over-predicted the overall pressure drop for the entire bundle in most tests. The 

differences between the predicted and measured pressure drops were well below the 
14

measurement uncertainty of 2.66 kPa (0.39 psi) only for Test 32013. In other cases, the 

deviation varied from 3~7 kPa (0.44~1.02 psi) though it was also a function of time. The 

pressure drop for a mid-level region (1.829 to 2.134 m (6 to 7 ft)) was also over-predicted for

most tests after some time when the bottom quench front approached close to the region. The 

same tendency was observed for the prediction of the pressure drop for a top region (3.048 to

3.353 m (10 to 11 ft)).

The code tended to over-predict the HTCs at all elevation for all tests after a well predicted, 

short period of vapor only cooling. The over-prediction of HTCs in a top region is smaller than 

that in a middle region due to the lack of a spacer grid model. 

In summary, RELAP5/MOD3.3 predicted the PCTs of the selected FLECHT-SEASET tests 

relatively well, within ±10% deviation. However, the code predicted quench times to occur much 

earlier than the measurement data. As the code over-predicted significantly the film boiling 

HTCs in most cases, the wall-to-fluid heat transfer models in that heat transfer regime should be 

investigated intensively. The overall tendency of over-predicting differential pressure for the 

entire core (or collapsed liquid level) indicates that the interfacial or wall drag models of the 

code may also have some deficiencies. By the way, the predicted differential pressures can

alter if the wall-to-fluid heat transfer models are changed. Thus, we focus on the wall-to-fluid 

heat transfer models first to improve the predictive capability for quench times. An intensive 

review and improvements of drag models is regarded as a future work.
15

3. MODIFICATION OF FILM BOILING WALL-TO-FLUID

HEAT TRANSFER MODELS

To improve the predictive capability mainly for quench times, the film boiling wall-to-fluid heat 

transfer models of RELAP5/MOD3.3, which are activated when the reflood option is invoked, 

were modified. The current models of RELAP5/MOD3.3 are discussed in brief first, and the 

modified models are described thereafter.

3.1 Brief of Current Models

Differently from other best-estimate codes like TRACE [9], COBRA/TRAC [10], or COBRA-TF 

[8], RELAP5/MOD3.3 does not draw a line between the inverted annular film boiling (IAFB) heat 

transfer regime and the dispersed flow film boiling (DFFB) heat transfer regime. It uses the 

same wall-to-fluid heat transfer models for the entire film boiling regime.

The code takes the maximum of HTCs calculated by three different correlations as the film 

boiling HTC to liquid.

wf Br FR CT h = max(h ,h ,h ) (2)

where hBr , hCT , and hFr are the HTCs calculated using the Bromley correlation, an empirical 

CATHARE correlation, and the Forslund-Rohsenow correlation, respectively.

The film boiling wall-to-vapor HTC is returned from the DITTUS subroutine. Here, in the default 

model, Ditt h is obtained by taking the maximum of a turbulent convective HTC calculated using 

the Dittus-Boelter correlation, a HTC corresponding to a constant laminar convective Nusselt 

number of 4.36, and a natural convective HTC calculated using the Churchill-Chu correlation. 

Note that the mass flux in the Dittus-Boelter correlation contains not only the vapor mass flux 

but also a portion of the liquid mass flux ( Gρf f g /⋅ρ ) in two-phase flow cases. Then, hDitt is void 

fraction ramped so that it goes to zero as the void fraction goes to zero.

h = h wg α Ditt g ⋅ (3)

RELAP5/MOD3.3 takes into account the wall-to-liquid radiation heat transfer in the film boiling 

regime and adds it to the wall-to-liquid convective heat transfer. The radiation heat transfer 

model of the code is based on that developed by Sun [11]. In this model, the radiation heat flux 

is proportional to the wall-to-liquid grey body factor given by

wf

3 3

2

1 2

1 F = 

R R R 1 + + 

R R

   

 

(4)

where R terms are given as a function of the emissivity of wall, vapor, and liquid. Constant 

values of 0.02 and 0.9 are assumed for the vapor emissivity and the wall emissivity, 

respectively. The liquid emissivity depends on the liquid absorption coefficient, f a which is 

defined as 
16

f

f

1.11α

a = 

d

⋅ (5)

where αf is the liquid volume fraction and d is the liquid droplet diameter which is given as 

the minimum of the following two expressions.

max g h d = 1 - αD ⋅ (6)

We=7.5 2

g r

7.5σ d =

ρv

⋅

⋅ (7)

More detailed information on the film boiling wall-to-fluid heat transfer models used in 

RELAP5/MOD3.3 can be found in the code manual [7].

3.2 Modified Models

In the modified version, the film boiling heat transfer regime is divided into three separate 

regimes. The IAFB and DFFB regimes are assumed to exist if void fractions are under 0.6 and 

over 0.9, respectively. Appropriate wall-to-fluid heat transfer correlations, described later, are 

used for each regime, and the HTCs in the region having void fractions between 0.6 and 0.9 are 

obtained by spline interpolation of the IAFB and DFFB HTCs:

wf wf,IA wf,DF h = y h + (1 - y) h ⋅ ⋅ (8)

h = y h + (1 - y) h wg wg,IA wg,DF ⋅ ⋅ (9)

where the weighting function, y is calculated from

y = x (2 - x) ⋅ with 

0.9 - αg x = 

0.9 - 0.6 (10)

Note that the void fraction limits defining each film boiling regime and the interpolation method 

are the same as used in TRACE [9].

For the IAFB wall-to-liquid HTC, the CATHARE correlation was selected among the three 

correlations in Eq.(2). 

0.5 h = [1400 - 1880 min(0.05, Z )] min(0.999 - wf,IA Qmin αg g MBr ⋅⋅ ⋅ , 0.5) + h (1 - α) (11)

where hMBr is calculated from a modified Bromley correlation.

0.25 3

g g fg w spt

MBr

Qmin g w spt

gρΔρk h + 0.5 (T - T )

h = 0.62

max(0.005, Z ) μ(T - T )

         

   

⋅⋅ ⋅ ⋅ ⋅ ⋅ ⋅ (12)

Here, ZQmin is the distance from the point in question to the bottom quench front. It replaces 

the wave length in the normal Bromley correlation. 
17

For the DFFB wall-to-liquid HTC, a modified Forslund-Rohsenow correlation was applied.

0.25

2/3 3

g g f fg

wf,DF BY 1/3

w g spt

6 (0.999 - α) gρρh k

h = 0.25 π

π

π (T - T ) μd 6

 

 

 

                     

⋅ ⋅⋅⋅ ⋅ Κ⋅ ⋅ ⋅

⋅ ⋅

(13)

where ΚBY is a function of the gas Reynolds number given as

0.6

g

BY

Re - 4000

Κ = 

100000

   

 

(14)

Eq.(13) is identical to the Forslund-Rohsenow correlation used to find FR h in Eq.(2) except 

that it has a Reynolds number dependent coefficient, ΚBY proposed by Bajorek and Young 

[12].

The IAFB wall-to-vapor HTC is given as a value corresponding to the conduction-only heat 

transfer:

h = 2 k / wg,IA g δ ⋅ (15)

where kg is the vapor conductivity and δ is the vapor film thickness in the rod bundle 

geometry obtained from geometrical consideration:

0.5 2 δ = 0.5 D 1 + h α[(4/π) (P/D ) - 1] - 1 g R

          ⋅⋅ ⋅ ⋅ (16)

Note that we followed the same approach as used in TRACE for calculating the IAFB wall-tovapor HTC.

The DFFB wall-to-vapor HTC in the modified version is determined from

h = [F h + (1 - F ) h ] wg,DF Φ ⋅ ⋅ 2p lt lam lt tur tur ⋅Φ ⋅ (17)

where htur is the single-phase turbulent convective HTC calculated using the Dittus-Boelter 

correlation. In this case only the vapor mass flux is used to find the Reynolds number. Φtur is 

a turbulent flow multiplier applied to a vertical bundle geometry and it is equal to the rod pitch to 

diameter ratio [7]. This multiplier can be used as an option in a calculation using the original 

version but it is not a part of the default model. lam h is the maximum of a single-phase laminar 

convective HTC corresponding to a constant Nusselt number of 10.0 and a single-phase natural 

convective HTC calculated using the Churchill-Chu correlation. Note that the laminar convective 

Nusselt number was increased from 4.36 to 10.0 because the former has been regarded as a 

value appropriate only for internal flows. The same laminar convective Nusselt number of 10.0 
18

has been used in COBRA/TRAC [10]. lt F is a linear function of the gas Reynolds number. It 

has a value of 1.0 at Reg = 3000 and a value of 0.0 at Reg = 10000 as proposed by Bajorek 

and Young [12]. Φ2p is a two-phase enhancement factor to account for increases in convective 

heat transfer due to the relative motion of vapor and droplets. A similar factor has been used not 

only in TRACE [9] but also in COBRA-TF [8]. The factor can be derived using a rough wall 

analogy [13]:

i w 2p w

τ + τ

 = 

τ

Φ (18)

where i τ and τw are friction forces per unit volume due to interfacial and wall drags, 

respectively and they are given in RELAP5/MOD3.3 as

2

w gw g h

1

τ=ρf v /D

2

⋅⋅⋅ (19)

2

i g r gf D

1

τ = ρa Cv

8

⋅⋅ ⋅ ⋅ (20)

where the interfacial area per unit volume, gf a , and the droplet drag coefficient, CD are in turn 

given as

f

gf

3.6α

a = 

d

⋅ (21)

0.75

d

D

d

24 (1 + 0.1 Re ) C = 

Re

⋅ ⋅ (22)

For the wall friction factor, fw in Eq.(19), a constant value corresponding to its fully developed 

one for a smooth pipe, 0.02 is assumed as in TRACE [9].

Four minor modifications were made to the radiation heat transfer model. First, the vapor 

emissivity is now obtained from the EMISS subroutine instead of using a constant value. The 

same subroutine is also used in TRACE to solve for the emissivity of liquid and vapor. Second, 

the wall emissivity was reduced to 0.7 to make the code agree with its manual. Third, the droplet 

diameter is now determined using the same method in subroutines FIDISV and FIDIS2, where 

the interfacial area is determined for bubbles and droplets. Note that the droplet diameter 

calculation method in these subroutines had a minor error which was corrected as described in 

Section 3.3. Fourth, a simpler approximation, that overrides Eq.(4), was introduced to find the 

wall-to-liquid grey body factor for the IAFB regime. 

wf

f f w

1 F =

1 1 + - 1

εα ε

   

  ⋅

(23)

The radiation heat transfers using the grey body factors in Eq.(4) and Eq.(23) are lumped into 

the wall-to-liquid heat transfer components for the DFFB and IAFB regimes, respectively.
19

3.3 Coding Error Corrections

As mentioned in the previous section, the subroutines calculating the interfacial area for bubbles 

and droplets contain a coding error. In subroutines FIDISV and FIDIS2, the average droplet 

diameter during reflood is given as

h d = min(D , dcon2, diam) (24)

where dcon2 = 0.0015 m for the post-CHF droplets and diam is defined as

We=1.5 diam = max(dmin, d ) (25)

where dmin = 0.0015 m if pressure is sufficiently low.

Equation (24) should be corrected because dcon2 is not a maximum but a minimum average 

droplet diameter as per Analytis [1]. The correct expression should read

h d = min(D , diam) (26)

Another coding error exists in the Weismann transition boiling wall-to-liquid HTC correlation. The 

correlation includes hmax which is defined as

''

CHF max

CHF

0.5 q h = 

ΔT

⋅ (27)

where ΔTCHF is the difference between the wall temperature at the CHF point and the 

saturation temperature according to Analytis [1]. However, it is coded as if it were the difference 

between the current wall temperature and the saturation temperature: 

ΔT = max[3,min(40,T - T )] CHF w sat (28)

The correct form of this parameter should be

ΔT = max[3,min(40,T - T )] CHF w,CHF sat (29)

From test calculations employing only these error corrections, it was revealed that they do not 

have a significant effect on the calculations for FLECHT-SEASET tests. Thus, the errors can be 

regarded as minor.

3.4 Effect of Modifications

To test the modifications, calculations for all the tests listed in Table 1 were conducted again 

using the modified version. The results are compared not only to those predicted by the original 

version but also to the measurement data in this section.

3.4.1 Test 31805
20

The predicted heater rod clad temperatures using the modified version at various elevations are 

presented in Figure 6 through Figure 13. The maximum predicted PCT is 1383 K at 1.981 m 

(6.5 ft) elevation while it was 1359 K at the same elevation with the original version. The 

predicted PCTs at all elevations are higher than those predicted using the original version and 

they locate between the maximum and minimum measured values at all elevations.

The predicted vapor temperatures at 1.829 m (6 ft) and 3.048 m (10 ft) elevations are presented

in Figure 14 and Figure 15, respectively. The predicted vapor temperatures at both elevations 

are higher than those predicted using the original version and closer to the measurements.

The predicted quench front is presented in Figure 16. The predictive capability for quench times 

was greatly improved by the modifications. The difference between the predicted quench time 

and the arithmetic average of measured quench times (predicted – measured) varies from -32 

to +2 seconds and the maximum absolute deviation occurred at 1.981 m (6.5 ft). The difference 

varied from -177 to -7 seconds when the original version was used.

The predicted and measured differential pressures for the entire core region, a mid-level (1.829 

to 2.134 m (6 to 7 ft)), and a top region (3.048 to 3.353 m (10 to 11 ft)) are presented in Figure 

17, Figure 18, and Figure 19, respectively. The predicted value for the entire core is still higher 

than the measurement data, but the deviation was slightly reduced by the modifications. The 

time when the predicted differential pressure for the mid-level becomes higher than the 

measurement was ~30 seconds delayed compared to the prediction using the original version. 

The predicted differential pressure for the top region was not altered much by the modifications 

except that the time of large oscillations were ~150 seconds delayed compared to the prediction 

using the original version. It means the liquid fraction in a top region was predicted to increase 

more slowly with the modified version than with the original version. 

The predicted and measured HTCs at five different elevations are presented in Figure 20 

through Figure 24. The predicted film boiling HTCs are still higher than the measured ones at 

most elevations, but the deviations were reduced compared to the predictions using the original 

version. The HTC at 3.048 m (10 ft) elevation agrees with the measured data very well.

3.4.2 Test 31504

The predicted heater rod clad temperatures using the modified version at various elevations are 

presented in Figure 25 through Figure 32. The maximum PCT predicted by the code is 1370 K 

at 1.981 m (6.5 ft) elevation while it was 1319 K at the same elevation with the original version.

The predicted PCTs are higher than those predicted using the original version and they locate 

between the maximum and minimum measured values at most elevations. Only the predicted 

PCT at 3.505 m (11.5 ft) is 41 K lower than that predicted using the original version.

The predicted vapor temperatures at 1.829 m (6 ft) and 3.048 m (10 ft) elevations are presented 

in Figure 33 and Figure 34, respectively. The predicted vapor temperatures at both elevations 

are higher than those predicted using the original version and closer to the measurements.

The predicted quench front is presented in Figure 35. The predictive capability for quench times 

was greatly improved by the modifications. Only the quench times at and below 1.219 m (4 ft) 

were slightly under-predicted and the difference between the predicted quench time and the 

arithmetic average of measured quench times (predicted – measured) varies from -15 to +14 
21

seconds and the maximum absolute deviation occurred at 1.219 m (4 ft). The difference varied 

from -149 to -5 seconds when the original version was used.

The predicted and measured differential pressures for the entire core region, a mid-level (1.829 

to 2.134 m (6 to 7 ft)), and a top region (3.048 to 3.353 m (10 to 11 ft)) are presented in Figure 

36, Figure 37, and Figure 38, respectively. The predicted value for the entire core is still higher 

than the measurement data, but the deviation was slightly reduced by the modifications. The 

time when the predicted differential pressure for the mid-level becomes higher than the 

measurement was ~50 seconds delayed compared to the prediction using the original version. 

The predicted differential pressure for the top region was not altered much by the modifications 

except that the time of large oscillations were ~100 seconds delayed compared to the prediction 

using the original version.

The predicted and measured HTCs at five different elevations are presented in Figure 39 

through Figure 43. The predicted film boiling HTCs are still higher than the measured ones at 

most elevations, but the deviations were reduced compared to the predictions using the original 

version. The HTCs at 2.438 m (8 ft) and 3.048 m (10 ft) elevations agree with the measured 

data fairly well.

3.4.3 Test 31203

The predicted heater rod clad temperatures using the modified version at various elevations are 

presented in Figure 44 through Figure 51. The maximum predicted PCT is 1265 K at 1.981 m 

(6.5 ft) elevation while it was 1224 K at 1.829 m (6.0 ft) elevation with the original version. The 

predicted PCTs are higher than those predicted using the original version and they locate 

between the maximum and minimum measured values at most elevations. Only the predicted 

PCT at 3.505 m (11.5 ft) is 11 K lower than that predicted using the original version.

The predicted vapor temperatures at 1.829 m (6 ft) and 3.048 m (10 ft) elevations are presented 

in Figure 52 and Figure 53, respectively. The predicted vapor temperatures at both elevations 

are higher than those predicted using the original version and closer to the measurements.

The predicted quench front is presented in Figure 54. The predictive capability for quench times 

was greatly improved by the modifications. However, the final quenches were still predicted to 

occur a little earlier than the measurements at most elevations. The difference between the 

predicted quench time and the arithmetic average of measured quench times (predicted –

measured) varies from -35 to +1 seconds and the maximum absolute deviation occurred at 

3.048 m (10 ft). The difference varied from -148 to -6 seconds when the original version was 

used.

The predicted and measured differential pressures for the entire core region, a mid-level (1.829 

to 2.134 m (6 to 7 ft)), and a top region (3.048 to 3.353 m (10 to 11 ft)) are presented in Figure 

55, Figure 56, and Figure 57, respectively. The predicted value for the entire core is still higher 

than the measurement data, but the deviation was slightly reduced by the modifications. The 

time when the predicted differential pressure for the mid-level becomes higher than the 

measurement was ~30 seconds delayed compared to the prediction using the original version. 

The predicted differential pressure for the top region was not altered much by the modifications 

except the time of large oscillations were ~100 seconds delayed compared to the prediction 

using the original version. 
22

The predicted and measured HTCs at five different elevations are presented in Figure 58 

through Figure 62. Though the film boiling HTCs were predicted relatively well, the transition 

boiling was predicted to occur earlier than the measurements.

3.4.4 Test 31302

The predicted heater rod clad temperatures using the modified version at various elevations are 

presented in Figure 63 through Figure 70. The maximum predicted PCT is 1166 K at 1.829 m 

(6.0 ft) elevation while it was 1159 K at the same elevation with the original version. The 

predicted PCTs are higher than those predicted using the original version and they locate 

between the maximum and minimum measured values at most elevations. The predicted PCT 

at 3.353 m (11 ft) is higher than the measurements just like that predicted using the original 

version.

The predicted vapor temperatures at 1.829 m (6 ft) and 3.048 m (10 ft) elevations are presented 

in Figure 71 and Figure 72, respectively. The predicted vapor temperatures at both elevations 

are slightly higher than those predicted using the original version. Time when the vapor loses 

superheating was delayed by the modifications at both elevations.

The predicted quench front is presented in Figure 73. The predictive capability for quench times 

was greatly improved by the modifications. However, the final quenches were still predicted to 

occur earlier than the measurements at most elevations. The difference between the predicted 

quench time and the arithmetic average of measured quench times (predicted – measured) 

varies from -57 to +38 seconds and the maximum absolute deviation occurred at 3.048 m (10 

ft). The difference varied from -120 to -7 seconds when the original version was used. Though 

the difference was reduced much by the modifications, the effect of modifications is rather 

limited compared to that observed for lower flooding rate tests (Test 31805, Test 31504, and 

Test 31203).

The predicted and measured differential pressures for the entire core region, a mid-level (1.829 

to 2.134 m (6 to 7 ft)), and a top region (3.048 to 3.353 m (10 to 11 ft)) are presented in Figure 

74, Figure 75, and Figure 76, respectively. The modified version predicted better the differential 

pressure for the entire core than the original version, especially after ~100 seconds. The time 

when the predicted differential pressure for the mid-level becomes higher than the 

measurement was ~30 seconds delayed compared to the prediction using the original version. 

The predicted differential pressure for the top region was not altered much by the modifications 

except that the time of large oscillations were ~60 seconds delayed compared to the prediction 

using the original version. 

The predicted and measured HTCs at five different elevations are presented in Figure 77 

through Figure 81. Though the film boiling HTCs were predicted relatively well, the transition 

boiling was predicted to start earlier than the measurements.

3.4.5 Test 31701

The predicted heater rod clad temperatures using the modified version at various elevations are 

presented in Figure 82 through Figure 89. The maximum predicted PCT is 1136 K at 1.829 m 

(6.0 ft) elevation while it was 1135 K at the same elevation with the original version. The 

predicted PCTs are slightly higher than those predicted using the original version at all 

elevations. They locate between the maximum and minimum measured values at all elevations

except 3.353 m (11 ft) elevation. 
23

The predicted vapor temperatures at 1.829 m (6 ft) and 3.048 m (10 ft) elevations are presented 

in Figure 90 and Figure 91, respectively. The peak vapor temperatures predicted at both 

elevations are not different much from those predicted using the original version. Only the time 

when the vapor loses superheating was delayed by the modifications.

The predicted quench front is presented in Figure 92. The predictive capability for quench times 

was a little improved by the modifications. However, the final quenches were still predicted to 

occur earlier than the measurements at most elevations. The difference between the predicted 

quench time and the arithmetic average of measured quench times (predicted – measured) 

varies from -30 to -1 seconds and the maximum absolute deviation occurred at 3.048 m (10 ft).

The difference varied from -41 to -3 seconds when the original version was used. Though the 

difference was reduced a little by the modifications, the effect of modifications is rather limited 

compared to that observed for the tests having relatively low flooding rates (Test 31805, Test 

31504, and Test 31203).

The predicted and measured differential pressures for the entire core region, a mid-level (1.829 

to 2.134 m (6 to 7 ft)), and a top region (3.048 to 3.353 m (10 to 11 ft)) are presented in Figure 

93, Figure 94, and Figure 95, respectively. The predicted value for the entire core is still higher 

than the measurement data, but the difference from the measurement was slightly reduced by 

the modifications. The time when the predicted differential pressure for the mid-level becomes 

higher than the measurement was ~15 seconds delayed compared to the prediction using the 

original version. The predicted differential pressure for the top region was not altered much by 

the modifications except the time of large oscillations were ~30 seconds delayed compared to 

the prediction using the original version.

The predicted and measured HTCs at five different elevations are presented in Figure 96 

through Figure 100. The predicted HTC at 1.219 m (4 ft) was not altered much by the 

modifications. The predictions for HTCs at other locations were improved a little, but the 

transition boiling was predicted to occur earlier than the measurements.

3.4.6 Test 31108

The predicted heater rod clad temperatures using the modified version at various elevations are 

presented in Figure 101 through Figure 108. The maximum PCT predicted by the code is 1167 

K at 1.981 m (6.5 ft) elevation while it was 1145 K at 1.829 m (6.0 ft) elevation with the original 

version. The predicted PCTs are higher than those predicted using the original version. The 

PCTs at and above 2.438 m (8 ft) were definitely over-predicted by the modified version. PCTs 

were predicted to occur later in time compared to not only the measurements but also the 

predictions using the original version.

The predicted vapor temperatures at 1.829 m (6 ft) and 3.048 m (10 ft) elevations are presented 

in Figure 109 and Figure 110. The predicted vapor temperatures at both elevations are nearly 

equal to or slightly higher than those predicted using the original version. The times when the 

vapor loses superheating were delayed by the modifications at both elevations.

The predicted quench front is presented in Figure 111. The predictive capability for quench 

times was much improved by the modifications. However, the final quenches were still predicted 

to occur earlier than the measurements at all elevations but 3.353 m (11 ft) and 3.505 m (11.5 ft) 

elevations. The difference between the predicted quench time and the arithmetic average of 

measured quench times (predicted – measured) varies from -77 to +130 seconds and the 
24

maximum absolute deviation occurred at 3.505 m (11.5 ft). The difference varied from -162 to 

+13 seconds when the original version was used. Though the predicted quench front went

closer to the measurement with the modifications, the top-down quenchings at a top region were 

not predicted well.

The predicted and measured differential pressures for the entire core region, a mid-level (1.829 

to 2.134 m (6 to 7 ft)), and a top region (3.048 to 3.353 m (10 to 11 ft)) are presented in Figure 

112, Figure 113, and Figure 114, respectively. The predicted value for the entire core is still 

higher than the measurement data, but the deviation was slightly reduced by the modifications. 

The time when the predicted differential pressure for the mid-level becomes higher than the 

measurement was ~40 seconds delayed compared to the prediction using the original version. 

The predicted differential pressure for the top region was not altered much by the modifications, 

but the large oscillations from ~150 seconds with the original version were replaced with a 

sudden increase at ~265 seconds.

The predicted and measured HTCs at five different elevations are presented in Figure 115 

through Figure 119. Though the film boiling HTCs were reduced compared those predicted 

using the original version, the transition boiling was still predicted to start earlier than 

measurements.

3.4.7 Test 32013

The predicted heater rod clad temperatures using the modified version at various elevations are 

presented in Figure 120 through Figure 127. The maximum predicted PCT is 1353 K at 1.981 m 

(6.5 ft) elevation while it was 1326 K at the same elevation with the original version. The 

predicted PCTs are higher than those predicted using the original version and they locate 

between the maximum and minimum measured values at all elevations. 

The predicted vapor temperatures at 1.829 m (6 ft) and 3.048 m (10 ft) elevations are presented 

in Figure 128 and Figure 129, respectively. The vapor temperatures increased for a longer time 

compared to the predictions with the original version. The time when the vapor loses 

superheating was delayed by the modifications at both elevations.

The predicted quench front is presented in Figure 130. The predictive capability for quench 

times was greatly improved by the modifications. Only the quench times at 0.610 m (2 ft), 1.219 

m (4 ft), and 3.048 m (10 ft) elevations were slightly under-predicted and the difference between 

the predicted quench time and the arithmetic average of measured quench times (predicted –

measured) varies from -7 to +12 seconds and the maximum absolute deviation occurred at 

3.353 m (11 ft). The difference varied from -101 to -2 seconds when the original version was 

used. 

The predicted and measured differential pressures for the entire core region, a mid-level (1.829 

to 2.134 m (6 to 7 ft)), and a top region (3.048 to 3.353 m (10 to 11 ft)) are presented in Figure 

131, Figure 132, and Figure 133, respectively. The predicted value for the entire core agrees 

with the measurement excellently. Even the small over-prediction by the original version was 

removed by the modifications. The prediction of the differential pressure for the mid-level was 

significantly improved by the modifications. The over-prediction with the original version which 

was observed after ~180 seconds was reduced to an acceptable level. The predicted differential 

pressure for the top region was not altered much by the modifications except that the time of 

large oscillations was ~100 seconds delayed compared to the prediction using the original 

version.
25

The predicted and measured HTCs at five different elevations are presented in Figure 134 

through Figure 138. The film boiling HTCs were predicted very well especially at or over 2.438 

m (8 ft) elevation. HTCs at other elevations were slightly over-predicted compared to the 

measurement data.

3.4.8 Test 32114

The predicted heater rod clad temperatures using the modified version at various elevations are 

presented in 139 through Figure 146. The maximum predicted PCT is 1356 K at 1.981 m (6.5 ft) 

elevation while it was 1320 K at the same elevation with the original version. The predicted 

PCTs are higher than those predicted using the original version and they locate between the 

maximum and minimum measured values at most elevations. The predicted PCT at 3.505 m 

(11.5 ft) is lower than that predicted with the original version while the predicted PCTs at 3.048 

m (10 ft) and 3.353 m (11 ft) are higher than the measurements.

The predicted vapor temperatures at 1.829 m (6 ft) and 3.048 m (10 ft) elevations are presented 

in Figure 147 and Figure 148, respectively. The predicted vapor temperatures at both elevations 

are slightly higher than those predicted using the original version. The time when the vapor 

loses superheating was delayed by the modifications at both elevations.

The predicted quench front is presented in Figure 149. The predictive capability for quench 

times was greatly improved by the modifications. However, the final quenches of 1.981 m (6.5 ft) 

elevation and lower elevations were predicted to occur slightly earlier than the measurements 

while the quenches over 1.981 m (6.5 ft) elevation were predicted to occur later than the 

measurements. The difference between the predicted quench time and the arithmetic average 

of measured quench times (predicted – measured) varies from -26 to +64 seconds and the 

maximum absolute deviation occurred at 3.048 m (10 ft). The difference varied from -113 to -15 

seconds when the original version was used. 

The predicted and measured differential pressures for the entire core region, a mid-level (1.829 

to 2.134 m (6 to 7 ft)), and a top region (3.048 to 3.353 m (10 to 11 ft)) are presented in Figure 

150, Figure 151, and Figure 152, respectively. The predicted value for the entire core is still 

higher than the measurement data, but the deviation was slightly reduced by the modifications. 

For the predicted differential pressure for the mid-level, the time when large oscillations occur 

was ~100 seconds delayed by the modifications. A similar effect of code modifications can be 

observed in the prediction for the differential pressure for the top region.

The predicted and measured HTCs at five different elevations are presented in Figure 153 

through Figure 157. Though the film boiling HTCs were reduced with the modifications, the 

HTCs at or below 1.981 m (6.5 ft) were predicted to increase to the magnitude of HTCs in the 

transition boiling earlier than the measurements.

3.4.9 All 8 Tests

Similar to Figure 158, the deviations of the predicted PCTs from the measurements are 

presented in Figure 160. The predictability for PCTs was not improved significantly but the RMS 

error in overall PCT predictions dropped from 48.3 to 36.7 K. Comparisons of the maxima and 

minima curves from Figures 158 and 160 in Figure 161 show more clearly the effect of the 

modifications. The largest PCT under-prediction dropped from 9.4 to 5.9%. Though the largest 

PCT over-prediction increased from 10.4 to 14.5% after the modifications, we believe that the 
26

results with the modified version is more reasonable because the code has no model to take 

into account the heat transfer enhancement by spacer grids, which is dominant at upper 

elevations. The improved predictability for PCTs can be assured by Figure 162 where all the 

predicted PCTs are plotted versus the measured ones. Least-square fitting curves before and 

after the modifications are also compared in this figure.

A similar but more significant effect of the modifications can be seen in terms of quench times. 

The differences between measurements and predictions with the modified version are 

presented in Figure 163, and the maxima and minima curves of Figure 163 are compared to 

those of Figure 159 in Figure 164. These figures indicate that quench times are better predicted 

with the modified version. The improved predictability for quench times can be seen more 

clearly in Figure 165 which presents the predicted quench times as a function of the measured 

ones. The RMS error in overall quench time predictions dropped from 85.9 to 32.1 seconds.

As shown in Eq.(2), the original code takes the maximum HTCs calculated by three different 

correlations as the film boiling HTC to liquid. That model may provide a good approximation for 

the IAFB HTC to liquid. However, it must over-predict the DFFB HTC to liquid because the HTC 

calculated with the CATHARE correlation is usually higher than that calculated with the 

Forslund-Rohsenow correlation. As we modified the code to use a modified Forslund-Rohsenow 

correlation for the DFFB HTC to liquid, the heat transfer to liquid must have been reduced.

On the contrary, the DFFB HTC to vapor was increased by the modifications. We introduced not 

only a turbulent flow multiplier but also a two-phase enhancement factor to the DFFB HTC to 

vapor, as shown in Eq.(17). These factors, as their names imply, have an effect of enhancing 

the wall-to-vapor heat transfer. As a result, the predicted vapor temperatures increased with the 

modifications. Though it is hard to say quantitatively since only two or three vapor temperature 

measurements are available at an elevation, the figures containing the vapor temperature 

predictions indicate that the DFFB HTC to vapor was modified to the right direction.

Note that even the modified version still over-predicts HTCs at lower or middle elevations. HTCs 

at higher elevations were predicted relatively well. However, if we had introduced a spacer grid 

model, it would have over-predicted also HTCs at higher elevations.

The code tends to over-predict the overall pressure drop for the entire bundle for most tests

even with the modifications. Though predictions were improved a little by the modifications, the 

differences between the predicted and measured pressure drops are greater than the 

measurement uncertainty for all tests except Test 32013. In addition, the pressure drop was 

over-predicted from the beginning of the transient. Thus, we suspect that this over-predicted 

pressure drop for the entire bundle (or collapsed liquid level) is one of the reasons for the overprediction of HTCs at lower and middle elevations.
27

4. CONCLUSIONS

The reflood model of RELAP5/MOD3.3 was assessed using eight FLECHT-SEASET tests. 

From the assessment, the following findings were obtained.

● The code predicts the measured PCTs within ±10% deviation.

● The code predicts rod quenches to occur significantly earlier than the measurement data.

● The code has a tendency of under-predicting peak vapor temperatures at 2 different 

elevations, especially those of low flooding rate tests. 

● The code has a tendency of over-predicting the overall pressure drop for the entire bundle.

Based on these findings, the wall-to-fluid heat transfer models which are activated during the 

reflood calculations were modified to improve the code’s predictability mainly for quench times. 

We divided the film boiling heat transfer regime into three different sub-regimes and selected 

appropriate heat transfer correlations for each sub-regime. In addition, we fixed minor coding 

errors in a few subroutines and modified slightly the radiation heat transfer model to assume 

more reasonable and consistent emissivity and droplet diameter.

Another set of calculations for the same FLECHT-SEASET tests were conducted with the 

modifications. From the comparisons of the predictions not only to the measurement data but 

also to the predictions using the original version, the following conclusions were derived.

● The RMS error in overall PCT predictions is reduced from 48.3 to 36.7 K by the 

modifications.

● The RMS error in overall quench time predictions is reduced from 85.9 to 32.1 s by the 

modifications.

● The film boiling HTCs predicted using the modified version shows better agreement with the 

measurement data compared to those predicted using the original version.

● Wall-to-vapor heat transfers were increased by the modifications so that the predicted vapor 

temperatures are higher than those predicted by the original version.

● Even with the modifications, the code still has a tendency of over-predicting the overall 

pressure drop for the entire core (or collapsed liquid level in the core). Thus, further efforts 

to improve the reflood model of RELAP5/MOD3.3 should be made to the wall or interfacial 

drag models.
28
29

5. REFERENCES

[1]. Analytis, G. Th., Developmental Assessment of RELAP5/MOD3.1 with Separate Effect and 

Integral Test Experiments: Model Changes and Options. Nuclear Engineering and Design,

163, p.125-148, 1996. 

[2]. Koszela, Z., Assessment of RELAP5/MOD3.2.2 Gamma against ABB Atom 3×3-Rod 

Bundle Reflooding Tests. Nuclear Engineering and Design, 223, p.49-73, 2003.

[3]. Chung, B. D. et al., Improvements to the RELAP5/MOD3 Reflood Model Assessment. 

Journal of Korean Nuclear Society, 26, p.265-276, 1994.

[4]. Baek, J. S. et al., Assessment of FLECHT SEASET Unblocked Forced Reflood Tests 

Using RELAP5/MOD3. Journal of Korean Nuclear Society, 24, p.297-310, 1992. 

[5]. Loftus, M. J. et al., PWR FLECHT-SEASET Unblocked Bundle, Force and Gravity Reflood 

Task Data Report, NUREG/CR-1532, 1980.

[6]. USNRC, TRACE V5.0 Assessment Manual, 2007. 

[7]. USNRC, RELAP5/MOD3.3 Code Manual. NUREG/CR-5535/Rev 1, 2001.

[8]. Westinghouse, Analysis of FLECHT SEASET 163-Rod Blocked Bundle Data Using 

COBRA-TF. NUREG/CR-4166, 1985.

[9]. USNRC, TRACE V5.0 Theory Manual, 2007. 

[10]. Thurgood, M. J. et al., COBRA/TRAC-A Thermal Hydraulic Code for Transient Analysis of 

Nuclear Reactor Vessels and Primary Coolant Systems. NUREG/CR-3046, 1983. 

[11]. Sun, K. H., Gonzales-Santalo, J. M., and Tien, C.L., Calculations of Combined Radiation 

and Convection Heat Transfer in Rod Bundles Under Emergency Cooling Conditions. 

Journal of Heat Transfer, 98:3, p.414-420, 1976. 

[12]. Bajorek, S. M. and Young, M. Y., Direct-Contact Heat Transfer Model for Dispersed-Flow 

Film Boiling. Nuclear Technology, 132, p.375-388, 2000.

[13]. Kays, W., Convective Heat and Mass Transfer. McGraw-Hill, p.348-349, 1993.
30

Table 1. FLECHT-SEASET Tests for RELAP5 Assessment

No. Test No.

Flooding 

Rate

Upper 

Plenum

Pressure 

Coolant Inlet 

Temperature 

Inlet

subcooling 

cm/s

(in/sec)

MPa

(psia)

K 

(°F)

K 

(°F)

1 31805 2.10

(0.81)

0.28

(40)

324 

(124)

79

(143)

2 31504 2.40

(0.97)

0.28

(40)

324 

(124)

79

(143)

3 31203 3.84

(1.51) 

0.28

(40)

325 

(126)

78

(141)

4 31302 7.65

(3.01)

0.28

(40)

325 

(126)

78

(141)

5 31701 15.50

(6.10)

0.28

(40)

326 

(127)

77

(140)

6 31108 7.90

(3.11)

0.13

(19)

306 

(91)

74

(134)

7 32013 2.64

(1.04)

0.41

(60)

339 

(150)

79

(143)

8 32114 2.5~3.1

(1.0~1.22)

0.28

(40)

408 

(257)

5

(10)
31

Figure 1. Facility Flow Diagram for Forced Reflood Tests
32

Figure 2. Cross-sectional View of Bundle Heated Section

Figure 3. Axial Power Profile of Heater Rods
33

Figure 4. FLECHT-SEASET RELAP5 Noding Diagram
34

0 100 200 300 400 500 600 700 800

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

 20 Nodes

Bottom Quench Front Elevation (m)

 49 Nodes

Time (s)

Figure 5. Effect of Axial Noding on Quench Front Elevation

0 100 200 300 400 500 600 700 800

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 6. Rod Clad Temperatures at 2 ft from Heated Bottom for Test 31805
35

0 100 200 300 400 500 600 700 800

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 7. Rod Clad Temperatures at 4 ft from Heated Bottom for Test 31805

0 100 200 300 400 500 600 700 800

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 8. Rod Clad Temperatures at 6 ft from Heated Bottom for Test 31805
36

0 100 200 300 400 500 600 700 800

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 9. Rod Clad Temperatures at 6.5 ft from Heated Bottom for Test 31805

0 100 200 300 400 500 600 700 800

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 10. Rod Clad Temperatures at 8 ft from Heated Bottom for Test 31805
37

0 100 200 300 400 500 600 700 800

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 11. Rod Clad Temperatures at 10 ft from Heated Bottom for Test 31805

0 100 200 300 400 500 600 700 800

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 12. Rod Clad Temperatures at 11 ft from Heated Bottom for Test 31805
38

0 100 200 300 400 500 600 700 800

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 13. Rod Clad Temperatures at 11.5 ft from Heated Bottom for Test 31805

0 100 200 300 400 500 600 700 800

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 14. Vapor Temperatures at 6 ft from Heated Bottom for Test 31805
39

0 100 200 300 400 500 600 700 800

300

400

500

600

700

800

900

1000

1100

1200

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 15. Vapor Temperatures at 10 ft from Heated Bottom for Test 31805

0 100 200 300 400 500 600 700 800

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Elevation (m)

Time (s)

Figure 16. Quench Profile as a Function of Time for Test 31805
40

0 100 200 300 400 500 600 700 800

0

10

20

30

40

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 17. Differential Pressure for the Entire 12 ft Core for Test 31805

0 100 200 300 400 500 600 700 800

0.0

0.5

1.0

1.5

2.0

2.5

3.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 18. Differential Pressure at 6~7 ft Elevation for Test 31805
41

0 100 200 300 400 500 600 700 800

0.0

0.5

1.0

1.5

2.0

2.5

3.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 19. Differential Pressure at 10~11 ft Elevation for Test 31805

0 100 200 300 400 500 600 700 800

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 20. Heat Transfer Coefficient at 4 ft from Heated Bottom for Test 31805
42

0 100 200 300 400 500 600 700 800

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 21. Heat Transfer Coefficient at 6 ft from Heated Bottom for Test 31805

0 100 200 300 400 500 600 700 800

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 22. Heat Transfer Coefficient at 6.5 ft from Heated Bottom for Test 31805
43

0 100 200 300 400 500 600 700 800

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 23. Heat Transfer Coefficient at 8 ft from Heated Bottom for Test 31805

0 100 200 300 400 500 600 700 800

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 24. Heat Transfer Coefficient at 10 ft from Heated Bottom for Test 31805
44

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 25. Rod Clad Temperatures at 2 ft from Heated Bottom for Test 31504

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 26. Rod Clad Temperatures at 4 ft from Heated Bottom for Test 31504
45

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 27. Rod Clad Temperatures at 6 ft from Heated Bottom for Test 31504

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 28. Rod Clad Temperatures at 6.5 ft from Heated Bottom for Test 31504
46

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 29. Rod Clad Temperatures at 8 ft from Heated Bottom for Test 31504

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 30. Rod Clad Temperatures at 10 ft from Heated Bottom for Test 31504
47

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 31. Rod Clad Temperatures at 11 ft from Heated Bottom for Test 31504

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 32. Rod Clad Temperatures at 11.5 ft from Heated Bottom for Test 31504
48

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 33. Vapor Temperatures at 6 ft from Heated Bottom for Test 31504

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 34. Vapor Temperatures at 10 ft from Heated Bottom for Test 31504
49

0 100 200 300 400 500 600 700

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Elevation (m)

Time (s)

Figure 35. Quench Profile as a Function of Time for Test 31504

0 100 200 300 400 500 600 700

0

10

20

30

40

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 36. Differential Pressure for the Entire 12 ft Core for Test 31504
50

0 100 200 300 400 500 600 700

0.0

0.5

1.0

1.5

2.0

2.5

3.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 37. Differential Pressure at 6~7 ft Elevation for Test 31504

0 100 200 300 400 500 600 700

0.0

0.5

1.0

1.5

2.0

2.5

3.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 38. Differential Pressure at 10~11 ft Elevation for Test 31504
51

0 100 200 300 400 500 600 700

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 39. Heat Transfer Coefficient at 4 ft from Heated Bottom for Test 31504

0 100 200 300 400 500 600 700

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 40. Heat Transfer Coefficient at 6 ft from Heated Bottom for Test 31504
52

0 100 200 300 400 500 600 700

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 41. Heat Transfer Coefficient at 6.5 ft from Heated Bottom for Test 31504

0 100 200 300 400 500 600 700

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 42. Heat Transfer Coefficient at 8 ft from Heated Bottom for Test 31504
53

0 100 200 300 400 500 600 700

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 43. Heat Transfer Coefficient at 10 ft from Heated Bottom for Test 31504

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 44. Rod Clad Temperatures at 2 ft from Heated Bottom for Test 31203
54

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 45. Rod Clad Temperatures at 4 ft from Heated Bottom for Test 31203

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 46. Rod Clad Temperatures at 6 ft from Heated Bottom for Test 31203
55

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 47. Rod Clad Temperatures at 6.5 ft from Heated Bottom for Test 31203

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 48. Rod Clad Temperatures at 8 ft from Heated Bottom for Test 31203
56

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 49. Rod Clad Temperatures at 10 ft from Heated Bottom for Test 31203

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 50. Rod Clad Temperatures at 11 ft from Heated Bottom for Test 31203
57

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 51. Rod Clad Temperatures at 11.5 ft from Heated Bottom for Test 31203

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

TIME (sec)

Figure 52. Vapor Temperatures at 6 ft from Heated Bottom for Test 31203
58

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 53. Vapor Temperatures at 10 ft from Heated Bottom for Test 31203

0 50 100 150 200 250 300 350 400 450 500

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Elevation (m)

Time (s)

Figure 54. Quench Profile as a Function of Time for Test 31203
59

0 50 100 150 200 250 300 350 400 450 500

0

10

20

30

40

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 55. Differential Pressure for the Entire 12 ft Core for Test 31203

0 50 100 150 200 250 300 350 400 450 500

0.0

0.5

1.0

1.5

2.0

2.5

3.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 56. Differential Pressure at 6~7 ft Elevation for Test 31203
60

0 50 100 150 200 250 300 350 400 450 500

0.0

0.5

1.0

1.5

2.0

2.5

3.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 57. Differential Pressure at 10~11 ft Elevation for Test 31203

0 50 100 150 200 250 300 350 400 450 500

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 58. Heat Transfer Coefficient at 4 ft from Heated Bottom for Test 31203
61

0 50 100 150 200 250 300 350 400 450 500

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 59. Heat Transfer Coefficient at 6 ft from Heated Bottom for Test 31203

0 50 100 150 200 250 300 350 400 450 500

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 60. Heat Transfer Coefficient at 6.5 ft from Heated Bottom for Test 31203
62

0 50 100 150 200 250 300 350 400 450 500

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 61. Heat Transfer Coefficient at 8 ft from Heated Bottom for Test 31203

0 50 100 150 200 250 300 350 400 450 500

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 62. Heat Transfer Coefficient at 10 ft from Heated Bottom for Test 31203
63

0 50 100 150 200 250 300

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 63. Rod Clad Temperatures at 2 ft from Heated Bottom for Test 31302

0 50 100 150 200 250 300

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 64. Rod Clad Temperatures at 4 ft from Heated Bottom for Test 31302
64

0 50 100 150 200 250 300

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 65. Rod Clad Temperatures at 6 ft from Heated Bottom for Test 31302

0 50 100 150 200 250 300

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 66. Rod Clad Temperatures at 6.5 ft from Heated Bottom for Test 31302
65

0 50 100 150 200 250 300

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 67. Rod Clad Temperatures at 8 ft from Heated Bottom for Test 31302

0 50 100 150 200 250 300

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 68. Rod Clad Temperatures at 10 ft from Heated Bottom for Test 31302
66

0 50 100 150 200 250 300

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 69. Rod Clad Temperatures at 11 ft from Heated Bottom for Test 31302

0 50 100 150 200 250 300

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 70. Rod Clad Temperatures at 11.5 ft from Heated Bottom for Test 31302
67

0 50 100 150 200 250 300

300

400

500

600

700

800

900

1000

1100

1200

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 71. Vapor Temperatures at 6 ft from Heated Bottom for Test 31302

0 50 100 150 200 250 300

300

400

500

600

700

800

900

1000

1100

1200

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 72. Vapor Temperatures at 10 ft from Heated Bottom for Test 31302
68

0 50 100 150 200 250 300

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Elevation (m)

Time (s)

Figure 73. Quench Profile as a Function of Time for Test 31302

0 50 100 150 200 250 300

0

10

20

30

40

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 74. Differential Pressure for the Entire 12 ft Core for Test 31302
69

0 50 100 150 200 250 300

0.0

0.5

1.0

1.5

2.0

2.5

3.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 75. Differential Pressure at 6~7 ft Elevation for Test 31302

0 50 100 150 200 250 300

0.0

0.5

1.0

1.5

2.0

2.5

3.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 76. Differential Pressure at 10~11 ft Elevation for Test 31302
70

0 50 100 150 200 250 300

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 77. Heat Transfer Coefficient at 4 ft from Heated Bottom for Test 31302

0 50 100 150 200 250 300

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 78. Heat Transfer Coefficient at 6 ft from Heated Bottom for Test 31302
71

0 50 100 150 200 250 300

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 79. Heat Transfer Coefficient at 6.5 ft from Heated Bottom for Test 31302

0 50 100 150 200 250 300

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 80. Heat Transfer Coefficient at 8 ft from Heated Bottom for Test 31302
72

0 50 100 150 200 250 300

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 81. Heat Transfer Coefficient at 10 ft from Heated Bottom for Test 31302

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 82. Rod Clad Temperatures at 2 ft from Heated Bottom for Test 31701
73

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 83. Rod Clad Temperatures at 4 ft from Heated Bottom for Test 31701

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 84. Rod Clad Temperatures at 6 ft from Heated Bottom for Test 31701
74

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 85. Rod Clad Temperatures at 6.5 ft from Heated Bottom for Test 31701

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 86. Rod Clad Temperatures at 8 ft from Heated Bottom for Test 31701
75

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 87. Rod Clad Temperatures at 10 ft from Heated Bottom for Test 31701

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 88. Rod Clad Temperatures at 11 ft from Heated Bottom for Test 31701
76

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 89. Rod Clad Temperatures at 11.5 ft from Heated Bottom for Test 31701

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

300

400

500

600

700

800

900

1000

1100

1200

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 90. Vapor Temperatures at 6 ft from Heated Bottom for Test 31701
77

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

300

400

500

600

700

800

900

1000

1100

1200

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 91. Vapor Temperatures at 10 ft from Heated Bottom for Test 31701

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Elevation (m)

Time (s)

Figure 92. Quench Profile as a Function of Time for Test 31701
78

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

0

10

20

30

40

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 93. Differential Pressure for the Entire 12 ft Core for Test 31701

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 94. Differential Pressure at 6~7 ft Elevation for Test 31701
79

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 95. Differential Pressure at 10~11 ft Elevation for Test 31701

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 96. Heat Transfer Coefficient at 4 ft from Heated Bottom for Test 31701
80

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 97. Heat Transfer Coefficient at 6 ft from Heated Bottom for Test 31701

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 98. Heat Transfer Coefficient at 6.5 ft from Heated Bottom for Test 31701
81

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 99. Heat Transfer Coefficient at 8 ft from Heated Bottom for Test 31701

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 100. Heat Transfer Coefficient at 10 ft from Heated Bottom for Test 31701
82

0 50 100 150 200 250 300 350 400

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 101. Rod Clad Temperatures at 2 ft from Heated Bottom for Test 31108

0 50 100 150 200 250 300 350 400

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 102. Rod Clad Temperatures at 4 ft from Heated Bottom for Test 31108
83

0 50 100 150 200 250 300 350 400

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 103. Rod Clad Temperatures at 6 ft from Heated Bottom for Test 31108

0 50 100 150 200 250 300 350 400

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 104. Rod Clad Temperatures at 6.5 ft from Heated Bottom for Test 31108
84

0 50 100 150 200 250 300 350 400

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 105. Rod Clad Temperatures at 8 ft from Heated Bottom for Test 31108

0 50 100 150 200 250 300 350 400

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 106. Rod Clad Temperatures at 10 ft from Heated Bottom for Test 31108
85

0 50 100 150 200 250 300 350 400

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 107. Rod Clad Temperatures at 11 ft from Heated Bottom for Test 31108

0 50 100 150 200 250 300 350 400

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 108. Rod Clad Temperatures at 11.5 ft from Heated Bottom for Test 31108
86

0 50 100 150 200 250 300 350 400

300

400

500

600

700

800

900

1000

1100

1200

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 109. Vapor Temperatures at 6 ft from Heated Bottom for Test 31108

0 50 100 150 200 250 300 350 400

300

400

500

600

700

800

900

1000

1100

1200

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 110. Vapor Temperatures at 10 ft from Heated Bottom for Test 31108
87

0 50 100 150 200 250 300 350 400

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Elevation (m)

Time (s)

Figure 111. Quench Profile as a Function of Time for Test 31108

0 50 100 150 200 250 300 350 400

0

10

20

30

40

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 112. Differential Pressure for the Entire 12 ft Core for Test 31108
88

0 50 100 150 200 250 300 350 400

0.0

0.5

1.0

1.5

2.0

2.5

3.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 113. Differential Pressure at 6~7 ft Elevation for Test 31108

0 50 100 150 200 250 300 350 400

0.0

0.5

1.0

1.5

2.0

2.5

3.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 114. Differential Pressure at 10~11 ft Elevation for Test 31108
89

0 50 100 150 200 250 300 350 400

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 115. Heat Transfer Coefficient at 4 ft from Heated Bottom for Test 31108

0 50 100 150 200 250 300 350 400

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 116. Heat Transfer Coefficient at 6 ft from Heated Bottom for Test 31108
90

0 50 100 150 200 250 300 350 400

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 117. Heat Transfer Coefficient at 6.5 ft from Heated Bottom for Test 31108

0 50 100 150 200 250 300 350 400

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 118. Heat Transfer Coefficient at 8 ft from Heated Bottom for Test 31108
91

0 50 100 150 200 250 300 350 400

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 119. Heat Transfer Coefficient at 10 ft from Heated Bottom for Test 31108

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 120. Rod Clad Temperatures at 2 ft from Heated Bottom for Test 32013
92

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 121. Rod Clad Temperatures at 4 ft from Heated Bottom for Test 32013

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 122. Rod Clad Temperatures at 6 ft from Heated Bottom for Test 32013
93

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 123. Rod Clad Temperatures at 6.5 ft from Heated Bottom for Test 32013

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 124. Rod Clad Temperatures at 8 ft from Heated Bottom for Test 32013
94

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 125. Rod Clad Temperatures at 10 ft from Heated Bottom for Test 32013

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 126. Rod Clad Temperatures at 11 ft from Heated Bottom for Test 32013
95

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 127. Rod Clad Temperatures at 11.5 ft from Heated Bottom for Test 32013

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 128. Vapor Temperatures at 6 ft from Heated Bottom for Test 32013
96

0 50 100 150 200 250 300 350 400 450 500

300

400

500

600

700

800

900

1000

1100

1200

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 129. Vapor Temperatures at 10 ft from Heated Bottom for Test 32013

0 50 100 150 200 250 300 350 400 450 500

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Elevation (m)

Time (s)

Figure 130. Quench Profile as a Function of Time for Test 32013
97

0 50 100 150 200 250 300 350 400 450 500

0

10

20

30

40

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 131. Differential Pressure for the Entire 12 ft Core for Test 32013

0 50 100 150 200 250 300 350 400 450 500

0.0

0.5

1.0

1.5

2.0

2.5

3.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 132. Differential Pressure at 6~7 ft Elevation for Test 32013
98

0 50 100 150 200 250 300 350 400 450 500

0.0

0.5

1.0

1.5

2.0

2.5

3.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 133. Differential Pressure at 10~11 ft Elevation for Test 32013

0 50 100 150 200 250 300 350 400 450 500

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 134. Heat Transfer Coefficient at 4 ft from Heated Bottom for Test 32013
99

0 50 100 150 200 250 300 350 400 450 500

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 135. Heat Transfer Coefficient at 6 ft from Heated Bottom for Test 32013

0 50 100 150 200 250 300 350 400 450 500

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 136. Heat Transfer Coefficient at 6.5 ft from Heated Bottom for Test 32013
100

0 50 100 150 200 250 300 350 400 450 500

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 137. Heat Transfer Coefficient at 8 ft from Heated Bottom for Test 32013

0 50 100 150 200 250 300 350 400 450 500

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 138. Heat Transfer Coefficient at 10 ft from Heated Bottom for Test 32013
101

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 139. Rod Clad Temperatures at 2 ft from Heated Bottom for Test 32114

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 140. Rod Clad Temperatures at 4 ft from Heated Bottom for Test 32114
102

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 141. Rod Clad Temperatures at 6 ft from Heated Bottom for Test 32114

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 142. Rod Clad Temperatures at 6.5 ft from Heated Bottom for Test 32114
103

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 143. Rod Clad Temperatures at 8 ft from Heated Bottom for Test 32114

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 144. Rod Clad Temperatures at 10 ft from Heated Bottom for Test 32114
104

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 145. Rod Clad Temperatures at 11 ft from Heated Bottom for Test 32114

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 146. Rod Clad Temperatures at 11.5 ft from Heated Bottom for Test 32114
105

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

1300

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 147. Vapor Temperatures at 6 ft from Heated Bottom for Test 32114

0 100 200 300 400 500 600 700

300

400

500

600

700

800

900

1000

1100

1200

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Temperature (K)

Time (s)

Figure 148. Vapor Temperatures at 10 ft from Heated Bottom for Test 32114
106

0 50 100 150 200 250 300 350 400 450 500 550 600 650 700

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Elevation (m)

Time (s)

Figure 149. Quench Profile as a Function of Time for Test 32114

0 100 200 300 400 500 600 700

0

10

20

30

40

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 150. Differential Pressure for the Entire 12 ft Core for Test 32114
107

0 100 200 300 400 500 600 700

0.0

0.5

1.0

1.5

2.0

2.5

3.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 151. Differential Pressure at 6~7 ft Elevation for Test 32114

0 100 200 300 400 500 600 700

0.0

0.5

1.0

1.5

2.0

2.5

3.0

 Measurement

 RELAP5 (Original)

 RELAP5 (Modified)

Differential Pressure (kPa)

Time (s)

Figure 152. Differential Pressure at 10~11 ft Elevation for Test 32114
108

0 100 200 300 400 500 600 700

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 153. Heat Transfer Coefficient at 4 ft from Heated Bottom for Test 32114

0 100 200 300 400 500 600 700

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 154. Heat Transfer Coefficient at 6 ft from Heated Bottom for Test 32114
109

0 100 200 300 400 500 600 700

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 155. Heat Transfer Coefficient at 6.5 ft from Heated Bottom for Test 32114

0 100 200 300 400 500 600 700

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 156. Heat Transfer Coefficient at 8 ft from Heated Bottom for Test 32114
110

0 100 200 300 400 500 600 700

0

100

200

300

400

500

 Measurement - Min.

 Measurement - Avg.

 Measurement - Max.

 RELAP5 (Original)

 RELAP5 (Modified)

HTC (W/m2-K)

Time (s)

Figure 157. Heat Transfer Coefficient at 10 ft from Heated Bottom for Test 32114

0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6

-15

-10

-5

0

5

10

15

20

25

31805

31504

31203

31302

31701

31108

32013

32114

(Predicted - Measured)/Measured (%)

Elevation (m)

Figure 158. Percent Deviations of Predicted PCTs with Original Version
111

0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6

-200

-150

-100

-50

0

50

100

150

200

250

300

31805

31504

31203

31302

31701

31108

32013

32114

Predicted - Measured (s)

Elevation (m)

Figure 159. Differences in Quench Times with Original Version

0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6

-15

-10

-5

0

5

10

15

20

25

31805

31504

31203

31302

31701

31108

32013

32114

(Predicted - Measured)/Measured (%)

Elevation (m)

Figure 160. Percent Deviations of Predicted PCTs with Modified Version
112

0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6

-15

-10

-5

0

5

10

15

20

25

 Maxima (Original)

 Minima (Original)

 Maxima (Modified)

 Minima (Modified)

(Predicted - Measured)/Measured (%)

Elevation (m)

Figure 161. Effect of Modifications on PCT Predictions

500 600 700 800 900 1000 1100 1200 1300 1400 1500

500

600

700

800

900

1000

1100

1200

1300

1400

1500

Original

Modified

Predicted PCT (K)

Measured PCT (K)

Original : y = 0.872*x + 108.6

Modified : y = 0.915*x + 86.5

Figure 162. Comparison of Predictability for PCTs
113

0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6

-200

-150

-100

-50

0

50

100

150

200

250

300

31805

31504

31203

31302

31701

31108

32013

32114

Predicted - Measured (s)

Elevation (m)

Figure 163. Differences in Quench Times with Modified Version

0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6

-200

-150

-100

-50

0

50

100

150

200

 Maxima (Original)

 Minima (Original)

 Maxima (Modified)

 Minima (Modified)

Predicted - Measured (s)

Elevation (m)

Figure 164. Effect of Modifications on Quench Time Predictions
114

0 100 200 300 400 500 600 700 800

0

100

200

300

400

500

600

700

800

Original : y = 0.761*x - 3.9

Modified : y = 1.036*x - 17.0

 Original

 Modified

Predicted Quench Time (s)

Measured Quench Time (s)

Figure 165. Comparison of Predictability for Quench Times
115

APPENDIX. RELAP5 BASE DECK FOR FLECHT-SEASET TEST 31805

=flecht seaset test no. 31805 using 49 nodes & 49 heat strs.

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

* option 50: original critical flow model

1 50

100 new transnt

101 run

102 si si

105 10.0 20.0

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

*

* time step

*

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

201 810.0 1.e-8 0.1 3 10 5000 5000

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

*

* mimor edits 

*

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

361 cntrlvar 005 * core collapsed water level

362 cntrlvar 110 * integrated water carry-over

363 cntrlvar 200 * total power

20800001 fij 200010000

20800002 fij 200020000

20800003 fij 200030000

20800004 fij 200040000

20800005 fij 200050000

20800006 fij 200060000

20800007 fij 200070000

20800008 fij 200080000

20800009 fij 200090000

20800010 fij 200100000

20800011 fij 200110000

20800012 fij 200120000

20800013 fij 200130000

20800014 fij 200140000

20800015 fij 200150000

20800016 fij 200160000

20800017 fij 200170000

20800018 fij 200180000

20800019 fij 200190000

20800020 fij 200200000

20800021 fij 200210000

20800022 fij 200220000

20800023 fij 200230000

20800024 fij 200240000

20800025 fij 200250000

20800026 fij 200260000

20800027 fij 200270000

20800028 fij 200280000

20800029 fij 200290000

20800030 fij 200300000

20800031 fij 200310000

20800032 fij 200320000
116

20800033 fij 200330000

20800034 fij 200340000

20800035 fij 200350000

20800036 fij 200360000

20800037 fij 200370000

20800038 fij 200380000

20800039 fij 200390000

20800040 fij 200400000

20800041 fij 200410000

20800042 fij 200420000

20800043 fij 200430000

20800044 fij 200440000

20800045 fij 200450000

20800046 fij 200460000

20800047 fij 200470000

20800048 fij 200480000

*

20800051 htmode 200100101

20800052 htmode 200100201

20800053 htmode 200100301

20800054 htmode 200100401

20800055 htmode 200100501

20800056 htmode 200100601

20800057 htmode 200100701

20800058 htmode 200100801

20800059 htmode 200100901

20800060 htmode 200101001

20800061 htmode 200101101

20800062 htmode 200101201

20800063 htmode 200101301

20800064 htmode 200101401

20800065 htmode 200101501

20800066 htmode 200101601

20800067 htmode 200101701

20800068 htmode 200101801

20800069 htmode 200101901

20800070 htmode 200102001

20800071 htmode 200102101

20800072 htmode 200102201

20800073 htmode 200102301

20800074 htmode 200102401

20800075 htmode 200102501

20800076 htmode 200102601

20800077 htmode 200102701

20800078 htmode 200102801

20800079 htmode 200102901

20800080 htmode 200103001

20800081 htmode 200103101

20800082 htmode 200103201

20800083 htmode 200103301

20800084 htmode 200103401

20800085 htmode 200103501

20800086 htmode 200103601

20800087 htmode 200103701

20800088 htmode 200103801

20800089 htmode 200103901

20800090 htmode 200104001
117

20800091 htmode 200104101

20800092 htmode 200104201

20800093 htmode 200104301

20800094 htmode 200104401

20800095 htmode 200104501

20800096 htmode 200104601

20800097 htmode 200104701

20800098 htmode 200104801

20800099 htmode 200104901

20800101 dt 0

20800102 dtcrnt 0

20800111 fines 2001

20800112 tchfqf 2001

20800113 trewet 2001

20800114 zqbot 2001

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

* 

* TRIP LOGICS 

* 

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

500 time 0 gt null 0 0.0 l -1.0

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

* 

* hydraulic components

* 

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

* inlet boundary volume

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

1000000 lplenum tmdpvol

1000101 1.0 1.0 0.0 0.0 0.0 0.0 0.0 0.0 00010

1000200 3 500

* test specific pressure and temperature

1000201 0.0 275790.0 326.2 

1000202 5.0 275790.0 326.8 

1000203 40.0 275790.0 323.8 

1000204 77.0 275790.0 323.8 

1000205 208.0 275790.0 325.6 

1000206 357.0 275790.0 325.6 

1000207 400.0 275790.0 326.2 

1000208 700.0 275790.0 326.2 

1000209 820.0 275790.0 326.2 

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

* inlet boundary junction

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

1500000 inlet tmdpjun

1500101 100000000 160000000 0.0155565

1500200 0 500

* test specific inlet velocity

1500201 0.0 0.01964 0.0 0.0 

1500202 12.4 0.02087 0.0 0.0 

1500203 160.0 0.01982 0.0 0.0 

1500204 228.0 0.01982 0.0 0.0 

1500205 230.0 0.02139 0.0 0.0 

1500206 280.0 0.02002 0.0 0.0 

1500207 338.5 0.02002 0.0 0.0 

1500208 349.5 0.02087 0.0 0.0 

1500209 820.0 0.02087 0.0 0.0 
118

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

* inlet volume

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

1600000 inletv snglvol 

1600101 0.0155565 0.00381 0.0 0.0 90. 0.00381 1.e-6 0.0097 00 

* test specific pressure and temperature

1600200 3 275790.0 326.2

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

* inlet junction

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

1650000 inletj sngljun

1650101 160010000 200000000 0.0 1.2 1.2 001000 

1650110 0.0097 0. 1. 1. 

1650201 1 0.0 0.0 0.0

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

* core

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

2000000 core pipe

2000001 49

2000101 0.0155565 49 * vol. flow area

2000201 0.0155565 48 * jun. flow area

2000301 0.0762 49 * vol. length

2000401 0.0 49 * vol. volume

2000601 90.0 49 * vol. vertical orientation

2000701 0.0762 49 * vol. elevation change

2000801 1.e-6 0.0097 49 * vol. friction data

* bottom most grid k --> junction to core inlet

2000901 0.0 0.0 6 * jun. loss coefficient

2000902 1.20 1.20 7

2000903 0.0 0.0 13

2000904 1.20 1.20 14

2000905 0.0 0.0 20

2000906 1.20 1.20 21

2000907 0.0 0.0 27

2000908 1.20 1.20 28

2000909 0.0 0.0 33

2000910 1.20 1.20 34

2000911 0.0 0.0 40

2000912 1.20 1.20 41

2000913 0.0 0.0 47

2000914 1.20 1.20 48

2001001 00100 49 * vol. control flag

2001101 000000 48 * jun. control flag

* test specific pressure and temperature

2001201 3 275790.0 403.8 0.0 0.0 0.0 1

2001202 3 275790.0 403.8 0.0 0.0 0.0 2

2001203 3 275790.0 415.5 0.0 0.0 0.0 3

2001204 3 275790.0 437.6 0.0 0.0 0.0 4

2001205 3 275790.0 459.6 0.0 0.0 0.0 5

2001206 3 275790.0 481.7 0.0 0.0 0.0 6

2001207 3 275790.0 503.8 0.0 0.0 0.0 7

2001208 3 275790.0 525.9 0.0 0.0 0.0 8

2001209 3 275790.0 548.0 0.0 0.0 0.0 9

2001210 3 275790.0 570.1 0.0 0.0 0.0 10

2001211 3 275790.0 592.1 0.0 0.0 0.0 11

2001212 3 275790.0 614.2 0.0 0.0 0.0 12

2001213 3 275790.0 636.3 0.0 0.0 0.0 13
119

2001214 3 275790.0 658.4 0.0 0.0 0.0 14

2001215 3 275790.0 680.5 0.0 0.0 0.0 15

2001216 3 275790.0 702.6 0.0 0.0 0.0 16

2001217 3 275790.0 724.6 0.0 0.0 0.0 17

2001218 3 275790.0 757.6 0.0 0.0 0.0 18

2001219 3 275790.0 790.5 0.0 0.0 0.0 19

2001220 3 275790.0 823.5 0.0 0.0 0.0 20

2001221 3 275790.0 856.4 0.0 0.0 0.0 21

2001222 3 275790.0 856.1 0.0 0.0 0.0 22

2001223 3 275790.0 855.9 0.0 0.0 0.0 23

2001224 3 275790.0 855.6 0.0 0.0 0.0 24

2001225 3 275790.0 855.3 0.0 0.0 0.0 25

2001226 3 275790.0 848.8 0.0 0.0 0.0 26

2001227 3 275790.0 842.4 0.0 0.0 0.0 27

2001228 3 275790.0 835.9 0.0 0.0 0.0 28

2001229 3 275790.0 829.4 0.0 0.0 0.0 29

2001230 3 275790.0 800.7 0.0 0.0 0.0 30

2001231 3 275790.0 772.0 0.0 0.0 0.0 31

2001232 3 275790.0 743.3 0.0 0.0 0.0 32

2001233 3 275790.0 714.6 0.0 0.0 0.0 33

2001234 3 275790.0 697.3 0.0 0.0 0.0 34

2001235 3 275790.0 680.1 0.0 0.0 0.0 35

2001236 3 275790.0 662.9 0.0 0.0 0.0 36

2001237 3 275790.0 645.7 0.0 0.0 0.0 37

2001238 3 275790.0 625.3 0.0 0.0 0.0 38

2001239 3 275790.0 604.9 0.0 0.0 0.0 39

2001240 3 275790.0 584.5 0.0 0.0 0.0 40

2001241 3 275790.0 564.1 0.0 0.0 0.0 41

2001242 3 275790.0 553.9 0.0 0.0 0.0 42

2001243 3 275790.0 543.8 0.0 0.0 0.0 43

2001244 3 275790.0 533.7 0.0 0.0 0.0 44

2001245 3 275790.0 523.6 0.0 0.0 0.0 45

2001246 3 275790.0 513.5 0.0 0.0 0.0 46

2001247 3 275790.0 503.4 0.0 0.0 0.0 47

2001248 3 275790.0 493.2 0.0 0.0 0.0 48

2001249 3 275790.0 483.1 0.0 0.0 0.0 49

2001300 0

2001301 0.0 0.0 0.0 48 * jun. initial condition

2001401 0.0097 0.0 1.0 1.0 48

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

* outlet junction

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

2500000 outlet sngljun

* ccfl on (f = 1)

* choking off (c = 1)

* reverse flow is restricted (kb = 1.e6)

2500101 200010000 300000000 0.0155565 0.0 1.e6 101000

2500102 1.0 1.0 1.0

2500201 0 0.0 0.0 0.0

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

* upper plenum

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

3000000 uplenum tmdpvol

3000101 1.0 1.0 0.0 0.0 0.0 0.0 0.0 0.0 00010

3000200 2

* test specific pressure

3000201 0.0 276550.0 1.0
120

3000202 820.0 276550.0 1.0 

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

*

* heat structure 

*

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

* fuel rod

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

*

12001000 49 8 2 0 0.0 1 1 32

12001100 0 1

12001101 2 1.20650e-3

12001102 1 2.22250e-3

12001103 2 4.11480e-3

12001104 2 4.74980e-3

12001201 1 2 * boron nitride

12001202 2 3 * kanthal

12001203 1 5 * boron nitride

12001204 4 7 * ss 347

12001301 0.0 2

12001302 1.0 3

12001303 0.0 7

12001400 -1

* test specific initial wall temperature

12001401 491.9 491.9 491.9 491.9 491.9 491.9 491.9 491.9 

12001402 515.3 515.3 515.3 515.3 515.3 515.3 515.3 515.3 

12001403 538.8 538.8 538.8 538.8 538.8 538.8 538.8 538.8 

12001404 562.2 562.2 562.2 562.2 562.2 562.2 562.2 562.2 

12001405 585.6 585.6 585.6 585.6 585.6 585.6 585.6 585.6 

12001406 609.1 609.1 609.1 609.1 609.1 609.1 609.1 609.1 

12001407 632.5 632.5 632.5 632.5 632.5 632.5 632.5 632.5 

12001408 655.9 655.9 655.9 655.9 655.9 655.9 655.9 655.9 

12001409 679.4 679.4 679.4 679.4 679.4 679.4 679.4 679.4 

12001410 727.4 727.4 727.4 727.4 727.4 727.4 727.4 727.4 

12001411 775.6 775.6 775.6 775.6 775.6 775.6 775.6 775.6 

12001412 823.8 823.8 823.8 823.8 823.8 823.8 823.8 823.8 

12001413 872.0 872.0 872.0 872.0 872.0 872.0 872.0 872.0 

12001414 920.1 920.1 920.1 920.1 920.1 920.1 920.1 920.1 

12001415 933.9 933.9 933.9 933.9 933.9 933.9 933.9 933.9 

12001416 947.5 947.5 947.5 947.5 947.5 947.5 947.5 947.5 

12001417 961.2 961.2 961.2 961.2 961.2 961.2 961.2 961.2 

12001418 989.6 989.6 989.6 989.6 989.6 989.6 989.6 989.6 

12001419 1017.9 1017.9 1017.9 1017.9 1017.9 1017.9 1017.9 1017.9 

12001420 1046.3 1046.3 1046.3 1046.3 1046.3 1046.3 1046.3 1046.3 

12001421 1074.7 1074.7 1074.7 1074.7 1074.7 1074.7 1074.7 1074.7 

12001422 1104.2 1104.2 1104.2 1104.2 1104.2 1104.2 1104.2 1104.2 

12001423 1133.6 1133.6 1133.6 1133.6 1133.6 1133.6 1133.6 1133.6 

12001424 1143.8 1143.8 1143.8 1143.8 1143.8 1143.8 1143.8 1143.8 

12001425 1126.3 1126.3 1126.3 1126.3 1126.3 1126.3 1126.3 1126.3 

12001426 1129.0 1129.0 1129.0 1129.0 1129.0 1129.0 1129.0 1129.0 

12001427 1115.2 1115.2 1115.2 1115.2 1115.2 1115.2 1115.2 1115.2 

12001428 1106.1 1106.1 1106.1 1106.1 1106.1 1106.1 1106.1 1106.1 

12001429 1097.0 1097.0 1097.0 1097.0 1097.0 1097.0 1097.0 1097.0 

12001430 1085.0 1085.0 1085.0 1085.0 1085.0 1085.0 1085.0 1085.0 

12001431 1072.9 1072.9 1072.9 1072.9 1072.9 1072.9 1072.9 1072.9 

12001432 1031.4 1031.4 1031.4 1031.4 1031.4 1031.4 1031.4 1031.4 

12001433 989.8 989.8 989.8 989.8 989.8 989.8 989.8 989.8 
121

12001434 933.5 933.5 933.5 933.5 933.5 933.5 933.5 933.5 

12001435 877.1 877.1 877.1 877.1 877.1 877.1 877.1 877.1 

12001436 862.2 862.2 862.2 862.2 862.2 862.2 862.2 862.2 

12001437 847.4 847.4 847.4 847.4 847.4 847.4 847.4 847.4 

12001438 832.4 832.4 832.4 832.4 832.4 832.4 832.4 832.4 

12001439 795.4 795.4 795.4 795.4 795.4 795.4 795.4 795.4 

12001440 758.4 758.4 758.4 758.4 758.4 758.4 758.4 758.4 

12001441 721.4 721.4 721.4 721.4 721.4 721.4 721.4 721.4 

12001442 698.3 698.3 698.3 698.3 698.3 698.3 698.3 698.3 

12001443 675.2 675.2 675.2 675.2 675.2 675.2 675.2 675.2 

12001444 652.1 652.1 652.1 652.1 652.1 652.1 652.1 652.1 

12001445 629.0 629.0 629.0 629.0 629.0 629.0 629.0 629.0 

12001446 614.8 614.8 614.8 614.8 614.8 614.8 614.8 614.8 

12001447 600.6 600.6 600.6 600.6 600.6 600.6 600.6 600.6 

12001448 586.4 586.4 586.4 586.4 586.4 586.4 586.4 586.4 

12001449 572.2 572.2 572.2 572.2 572.2 572.2 572.2 572.2 

* test specific length (159 rods)

12001501 0 0 0 1 6.05790 1

12001502 0 0 0 1 12.11580 48

12001503 0 0 0 1 6.05790 49

12001601 200010000 0 1 1 6.05790 1

12001602 200020000 10000 1 1 12.11580 48

12001603 200490000 0 1 1 6.05790 49

* test specific power fraction

12001701 200 0.00447 0.0 0.0 1

12001702 200 0.00895 0.0 0.0 2

12001703 200 0.00895 0.0 0.0 3

12001704 200 0.00895 0.0 0.0 4

12001705 200 0.00895 0.0 0.0 5

12001706 200 0.00895 0.0 0.0 6

12001707 200 0.00895 0.0 0.0 7

12001708 200 0.01051 0.0 0.0 8

12001709 200 0.01415 0.0 0.0 9 

12001710 200 0.01415 0.0 0.0 10 

12001711 200 0.01790 0.0 0.0 11 

12001712 200 0.01832 0.0 0.0 12 

12001713 200 0.02071 0.0 0.0 13 

12001714 200 0.02310 0.0 0.0 14 

12001715 200 0.02349 0.0 0.0 15 

12001716 200 0.02706 0.0 0.0 16 

12001717 200 0.02706 0.0 0.0 17 

12001718 200 0.02981 0.0 0.0 18 

12001719 200 0.03101 0.0 0.0 19 

12001720 200 0.03172 0.0 0.0 20 

12001721 200 0.03330 0.0 0.0 21 

12001722 200 0.03330 0.0 0.0 22 

12001723 200 0.03443 0.0 0.0 23 

12001724 200 0.03455 0.0 0.0 24 

12001725 200 0.03455 0.0 0.0 25 

12001726 200 0.03455 0.0 0.0 26 

12001727 200 0.03442 0.0 0.0 27 

12001728 200 0.03330 0.0 0.0 28 

12001729 200 0.03330 0.0 0.0 29 

12001730 200 0.03168 0.0 0.0 30 

12001731 200 0.03101 0.0 0.0 31 

12001732 200 0.02984 0.0 0.0 32 

12001733 200 0.02706 0.0 0.0 33 
122

12001734 200 0.02706 0.0 0.0 34 

12001735 200 0.02350 0.0 0.0 35 

12001736 200 0.02310 0.0 0.0 36 

12001737 200 0.02071 0.0 0.0 37 

12001738 200 0.01832 0.0 0.0 38 

12001739 200 0.01790 0.0 0.0 39 

12001740 200 0.01415 0.0 0.0 40 

12001741 200 0.01415 0.0 0.0 41 

12001742 200 0.01051 0.0 0.0 42 

12001743 200 0.00895 0.0 0.0 43 

12001744 200 0.00895 0.0 0.0 44 

12001745 200 0.00895 0.0 0.0 45 

12001746 200 0.00895 0.0 0.0 46 

12001747 200 0.00895 0.0 0.0 47 

12001748 200 0.00895 0.0 0.0 48 

12001749 200 0.00447 0.0 0.0 49

* additional left boundary

12001801 0.0094996 20.0 20.0 0.0 0.0 0.0 0.0 1.0 49

* additional right boundary

12001901 0.0094996 0.03810 3.65760 0.00000 0.48890 1.20 1.20 0.24250 1

12001902 0.0094996 0.07620 3.58140 0.07620 0.41270 1.20 1.20 0.29458 2

12001903 0.0094996 0.15240 3.50520 0.15240 0.33650 1.20 1.20 0.34667 3

12001904 0.0094996 0.22860 3.42900 0.22860 0.26030 1.20 1.20 0.39875 4

12001905 0.0094996 0.30480 3.35280 0.30480 0.18410 1.20 1.20 0.45083 5

12001906 0.0094996 0.38100 3.27660 0.38100 0.10790 1.20 1.20 0.50292 6

12001907 0.0094996 0.45720 3.20040 0.45720 0.03170 1.20 1.20 0.55500 7

12001908 0.0094996 0.53340 3.12420 0.00000 0.46360 1.20 1.20 0.60708 8

12001909 0.0094996 0.60960 3.04800 0.07620 0.38740 1.20 1.20 0.65917 9

12001910 0.0094996 0.68580 2.97180 0.15240 0.31120 1.20 1.20 0.73000 10

12001911 0.0094996 0.76200 2.89560 0.22860 0.23500 1.20 1.20 0.81333 11

12001912 0.0094996 0.83820 2.81940 0.30480 0.15880 1.20 1.20 0.89917 12

12001913 0.0094996 0.91440 2.74320 0.38100 0.08260 1.20 1.20 0.99500 13

12001914 0.0094996 0.99060 2.66700 0.45720 0.00640 1.20 1.20 1.09083 14

12001915 0.0094996 1.06680 2.59080 0.02530 0.46360 1.20 1.20 1.17333 15

12001916 0.0094996 1.14300 2.51460 0.10150 0.38740 1.20 1.20 1.25249 16

12001917 0.0094996 1.21920 2.43840 0.17770 0.31120 1.20 1.20 1.33166 17

12001918 0.0094996 1.29540 2.36220 0.25390 0.23500 1.20 1.20 1.41082 18

12001919 0.0094996 1.37160 2.28600 0.33010 0.15880 1.20 1.20 1.48998 19

12001920 0.0094996 1.44780 2.20980 0.40630 0.08260 1.20 1.20 1.53583 20

12001921 0.0094996 1.52400 2.13360 0.48250 0.00640 1.20 1.20 1.58168 21

12001922 0.0094996 1.60020 2.05740 0.02530 0.46360 1.20 1.20 1.61000 22

12001923 0.0094996 1.67640 1.98120 0.10150 0.38740 1.20 1.20 1.62667 23

12001924 0.0094996 1.75260 1.90500 0.17770 0.31120 1.20 1.20 1.64334 24

12001925 0.0094996 1.82880 1.82880 0.25390 0.23500 1.20 1.20 1.66000 25

12001926 0.0094996 1.90500 1.75260 0.33010 0.15880 1.20 1.20 1.64333 26

12001927 0.0094996 1.98120 1.67640 0.40630 0.08260 1.20 1.20 1.62667 27

12001928 0.0094996 2.05740 1.60020 0.48250 0.00640 1.20 1.20 1.61000 28

12001929 0.0094996 2.13360 1.52400 0.02530 0.43830 1.20 1.20 1.58167 29

12001930 0.0094996 2.20980 1.44780 0.10150 0.36210 1.20 1.20 1.53584 30

12001931 0.0094996 2.28600 1.37160 0.17770 0.28590 1.20 1.20 1.49001 31

12001932 0.0094996 2.36220 1.29540 0.25390 0.20970 1.20 1.20 1.41084 32

12001933 0.0094996 2.43840 1.21920 0.33010 0.13350 1.20 1.20 1.33165 33

12001934 0.0094996 2.51460 1.14300 0.40630 0.05730 1.20 1.20 1.25248 34

12001935 0.0094996 2.59080 1.06680 0.48250 0.51450 1.20 1.20 1.17332 35

12001936 0.0094996 2.66700 0.99060 0.05090 0.43830 1.20 1.20 1.09082 36

12001937 0.0094996 2.74320 0.91440 0.12710 0.36210 1.20 1.20 0.99499 37

12001938 0.0094996 2.81940 0.83820 0.20330 0.28590 1.20 1.20 0.89917 38
123

12001939 0.0094996 2.89560 0.76200 0.27950 0.20970 1.20 1.20 0.81334 39

12001940 0.0094996 2.97180 0.68580 0.35570 0.13350 1.20 1.20 0.73001 40

12001941 0.0094996 3.04800 0.60960 0.43190 0.05730 1.20 1.20 0.65917 41

12001942 0.0094996 3.12420 0.53340 0.50810 0.48890 1.20 1.20 0.60709 42

12001943 0.0094996 3.20040 0.45720 0.05090 0.41270 1.20 1.20 0.55501 43

12001944 0.0094996 3.27660 0.38100 0.12710 0.33650 1.20 1.20 0.50293 44

12001945 0.0094996 3.35280 0.30480 0.20330 0.26030 1.20 1.20 0.45085 45

12001946 0.0094996 3.42900 0.22860 0.27950 0.18410 1.20 1.20 0.39877 46

12001947 0.0094996 3.50520 0.15240 0.35570 0.10790 1.20 1.20 0.34668 47

12001948 0.0094996 3.58140 0.07620 0.43190 0.03170 1.20 1.20 0.29460 48

12001949 0.0094996 3.65760 0.03810 0.00000 20.0000 1.20 1.20 0.24252 49

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

* housing

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

12002000 49 3 2 0 0.097 0 0

12002100 0 1

12002101 2 0.10208

12002201 3 2 * ss 304

12002301 0. 2

12002400 -1

* test specific initial wall temperature

12002401 368.2 368.2 368.2 

12002402 372.2 372.2 372.2 

12002403 376.2 376.2 376.2 

12002404 380.2 380.2 380.2 

12002405 384.2 384.2 384.2 

12002406 388.2 388.2 388.2 

12002407 392.2 392.2 392.2 

12002408 396.2 396.2 396.2 

12002409 400.2 400.2 400.2 

12002410 404.2 404.2 404.2 

12002411 408.2 408.2 408.2 

12002412 412.2 412.2 412.2 

12002413 416.2 416.2 416.2 

12002414 420.2 420.2 420.2 

12002415 424.2 424.2 424.2 

12002416 428.2 428.2 428.2 

12002417 432.2 432.2 432.2 

12002418 435.8 435.8 435.8 

12002419 439.4 439.4 439.4 

12002420 443.0 443.0 443.0 

12002421 446.7 446.7 446.7 

12002422 450.3 450.3 450.3 

12002423 453.9 453.9 453.9 

12002424 457.5 457.5 457.5 

12002425 461.2 461.2 461.2 

12002426 458.4 458.4 458.4 

12002427 455.7 455.7 455.7 

12002428 452.9 452.9 452.9 

12002429 450.2 450.2 450.2 

12002430 447.4 447.4 447.4 

12002431 444.7 444.7 444.7 

12002432 441.9 441.9 441.9 

12002433 439.2 439.2 439.2 

12002434 436.9 436.9 436.9 

12002435 434.7 434.7 434.7 

12002436 432.4 432.4 432.4 
124

12002437 430.2 430.2 430.2 

12002438 425.9 425.9 425.9 

12002439 421.7 421.7 421.7 

12002440 417.4 417.4 417.4 

12002441 413.2 413.2 413.2 

12002442 411.9 411.9 411.9 

12002443 410.7 410.7 410.7 

12002444 409.4 409.4 409.4 

12002445 408.2 408.2 408.2 

12002446 406.9 406.9 406.9 

12002447 405.7 405.7 405.7 

12002448 404.4 404.4 404.4 

12002449 403.2 403.2 403.2 

12002501 200010000 0 1 1 0.0381 1

12002502 200020000 10000 1 1 0.0762 48

12002503 200490000 0 1 1 0.0381 49

12002601 0 0 0 1 0.0381 1 

12002602 0 0 0 1 0.0762 48

12002603 0 0 0 1 0.0381 49

12002701 0 0.0 0.0 0.0 49

12002801 0.0 20.0 20.0 0.0 0.0 0.0 0.0 1.0 49

12002901 0.0 20.0 20.0 0.0 0.0 0.0 0.0 1.0 49

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

* thimbles

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

12003000 49 3 2 0 0.005461 0 1

12003100 0 1

12003101 2 0.0060198

12003201 3 2 * ss 304

12003301 0.0 2

12003400 -1

* test specific initial wall temp.

12003401 368.2 368.2 368.2 

12003402 372.2 372.2 372.2 

12003403 376.2 376.2 376.2 

12003404 380.2 380.2 380.2 

12003405 384.2 384.2 384.2 

12003406 388.2 388.2 388.2 

12003407 392.2 392.2 392.2 

12003408 396.2 396.2 396.2 

12003409 400.2 400.2 400.2 

12003410 404.2 404.2 404.2 

12003411 408.2 408.2 408.2 

12003412 412.2 412.2 412.2 

12003413 416.2 416.2 416.2 

12003414 420.2 420.2 420.2 

12003415 424.2 424.2 424.2 

12003416 428.2 428.2 428.2 

12003417 432.2 432.2 432.2 

12003418 435.8 435.8 435.8 

12003419 439.4 439.4 439.4 

12003420 443.0 443.0 443.0 

12003421 446.7 446.7 446.7 

12003422 450.3 450.3 450.3 

12003423 453.9 453.9 453.9 

12003424 457.5 457.5 457.5 

12003425 461.2 461.2 461.2 
125

12003426 458.4 458.4 458.4 

12003427 455.7 455.7 455.7 

12003428 452.9 452.9 452.9 

12003429 450.2 450.2 450.2 

12003430 447.4 447.4 447.4 

12003431 444.7 444.7 444.7 

12003432 441.9 441.9 441.9 

12003433 439.2 439.2 439.2 

12003434 436.9 436.9 436.9 

12003435 434.7 434.7 434.7 

12003436 432.4 432.4 432.4 

12003437 430.2 430.2 430.2 

12003438 425.9 425.9 425.9 

12003439 421.7 421.7 421.7 

12003440 417.4 417.4 417.4 

12003441 413.2 413.2 413.2 

12003442 411.9 411.9 411.9 

12003443 410.7 410.7 410.7 

12003444 409.4 409.4 409.4 

12003445 408.2 408.2 408.2 

12003446 406.9 406.9 406.9 

12003447 405.7 405.7 405.7 

12003448 404.4 404.4 404.4 

12003449 403.2 403.2 403.2 

* 16 thimbles 

12003501 0 0 0 1 0.6096 1

12003502 0 0 0 1 1.2192 48

12003503 0 0 0 1 0.6096 49

12003601 200010000 0 1 1 0.6096 1 

12003602 200020000 10000 1 1 1.2192 48 

12003603 200490000 0 1 1 0.6096 49 

12003701 0 0.0 0.0 0.0 49 

12003801 0.0 20.0 20.0 0.0 0.0 0.0 0.0 1.0 49

12003901 0.0 20.0 20.0 0.0 0.0 0.0 0.0 1.0 49

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

* fillers

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

12004000 49 3 2 0 0.0 0 1

12004100 0 1

12004101 2 0.005022

12004201 3 2

12004301 0.0 2

12004400 -1

* test specific initial wall temp.

12004401 368.2 368.2 368.2 

12004402 372.2 372.2 372.2 

12004403 376.2 376.2 376.2 

12004404 380.2 380.2 380.2 

12004405 384.2 384.2 384.2 

12004406 388.2 388.2 388.2 

12004407 392.2 392.2 392.2 

12004408 396.2 396.2 396.2 

12004409 400.2 400.2 400.2 

12004410 404.2 404.2 404.2 

12004411 408.2 408.2 408.2 

12004412 412.2 412.2 412.2 

12004413 416.2 416.2 416.2 
126

12004414 420.2 420.2 420.2 

12004415 424.2 424.2 424.2 

12004416 428.2 428.2 428.2 

12004417 432.2 432.2 432.2 

12004418 435.8 435.8 435.8 

12004419 439.4 439.4 439.4 

12004420 443.0 443.0 443.0 

12004421 446.7 446.7 446.7 

12004422 450.3 450.3 450.3 

12004423 453.9 453.9 453.9 

12004424 457.5 457.5 457.5 

12004425 461.2 461.2 461.2 

12004426 458.4 458.4 458.4 

12004427 455.7 455.7 455.7 

12004428 452.9 452.9 452.9 

12004429 450.2 450.2 450.2 

12004430 447.4 447.4 447.4 

12004431 444.7 444.7 444.7 

12004432 441.9 441.9 441.9 

12004433 439.2 439.2 439.2 

12004434 436.9 436.9 436.9 

12004435 434.7 434.7 434.7 

12004436 432.4 432.4 432.4 

12004437 430.2 430.2 430.2 

12004438 425.9 425.9 425.9 

12004439 421.7 421.7 421.7 

12004440 417.4 417.4 417.4 

12004441 413.2 413.2 413.2 

12004442 411.9 411.9 411.9 

12004443 410.7 410.7 410.7 

12004444 409.4 409.4 409.4 

12004445 408.2 408.2 408.2 

12004446 406.9 406.9 406.9 

12004447 405.7 405.7 405.7 

12004448 404.4 404.4 404.4 

12004449 403.2 403.2 403.2 

* 8 fillers

12004501 0 0 0 1 0.3048 1

12004502 0 0 0 1 0.6096 48

12004503 0 0 0 1 0.3048 49

12004601 200010000 0 1 1 0.3048 1

12004602 200020000 10000 1 1 0.6096 48 

12004603 200490000 0 1 1 0.3048 49 

12004701 0 0.0 0.0 0.0 49

12004801 0.0 20.0 20.0 0.0 0.0 0.0 0.0 1.0 49

12004901 0.0 20.0 20.0 0.0 0.0 0.0 0.0 1.0 49

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

* failed rods

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

12005000 49 8 2 0 0.0 0 1

12005100 0 1

12005101 2 1.20650e-3

12005102 1 2.22250e-3

12005103 2 4.11480e-3

12005104 2 4.74980e-3

12005201 1 2 * boron nitride

12005202 2 3 * kanthal
127

12005203 1 5 * boron nitride

12005204 4 7 * ss 347

12005301 0.0 2

12005302 1.0 3

12005303 0.0 7

12005400 -1

* test specific initial wall temperature

12005401 368.2 368.2 368.2 368.2 368.2 368.2 368.2 368.2 

12005402 372.2 372.2 372.2 372.2 372.2 372.2 372.2 372.2 

12005403 376.2 376.2 376.2 376.2 376.2 376.2 376.2 376.2 

12005404 380.2 380.2 380.2 380.2 380.2 380.2 380.2 380.2 

12005405 384.2 384.2 384.2 384.2 384.2 384.2 384.2 384.2 

12005406 388.2 388.2 388.2 388.2 388.2 388.2 388.2 388.2 

12005407 392.2 392.2 392.2 392.2 392.2 392.2 392.2 392.2 

12005408 396.2 396.2 396.2 396.2 396.2 396.2 396.2 396.2 

12005409 400.2 400.2 400.2 400.2 400.2 400.2 400.2 400.2 

12005410 404.2 404.2 404.2 404.2 404.2 404.2 404.2 404.2 

12005411 408.2 408.2 408.2 408.2 408.2 408.2 408.2 408.2 

12005412 412.2 412.2 412.2 412.2 412.2 412.2 412.2 412.2 

12005413 416.2 416.2 416.2 416.2 416.2 416.2 416.2 416.2 

12005414 420.2 420.2 420.2 420.2 420.2 420.2 420.2 420.2 

12005415 424.2 424.2 424.2 424.2 424.2 424.2 424.2 424.2 

12005416 428.2 428.2 428.2 428.2 428.2 428.2 428.2 428.2 

12005417 432.2 432.2 432.2 432.2 432.2 432.2 432.2 432.2 

12005418 435.8 435.8 435.8 435.8 435.8 435.8 435.8 435.8 

12005419 439.4 439.4 439.4 439.4 439.4 439.4 439.4 439.4 

12005420 443.0 443.0 443.0 443.0 443.0 443.0 443.0 443.0 

12005421 446.7 446.7 446.7 446.7 446.7 446.7 446.7 446.7 

12005422 450.3 450.3 450.3 450.3 450.3 450.3 450.3 450.3 

12005423 453.9 453.9 453.9 453.9 453.9 453.9 453.9 453.9 

12005424 457.5 457.5 457.5 457.5 457.5 457.5 457.5 457.5 

12005425 461.2 461.2 461.2 461.2 461.2 461.2 461.2 461.2 

12005426 458.4 458.4 458.4 458.4 458.4 458.4 458.4 458.4 

12005427 455.7 455.7 455.7 455.7 455.7 455.7 455.7 455.7 

12005428 452.9 452.9 452.9 452.9 452.9 452.9 452.9 452.9 

12005429 450.2 450.2 450.2 450.2 450.2 450.2 450.2 450.2 

12005430 447.4 447.4 447.4 447.4 447.4 447.4 447.4 447.4 

12005431 444.7 444.7 444.7 444.7 444.7 444.7 444.7 444.7 

12005432 441.9 441.9 441.9 441.9 441.9 441.9 441.9 441.9 

12005433 439.2 439.2 439.2 439.2 439.2 439.2 439.2 439.2 

12005434 436.9 436.9 436.9 436.9 436.9 436.9 436.9 436.9 

12005435 434.7 434.7 434.7 434.7 434.7 434.7 434.7 434.7 

12005436 432.4 432.4 432.4 432.4 432.4 432.4 432.4 432.4 

12005437 430.2 430.2 430.2 430.2 430.2 430.2 430.2 430.2 

12005438 425.9 425.9 425.9 425.9 425.9 425.9 425.9 425.9 

12005439 421.7 421.7 421.7 421.7 421.7 421.7 421.7 421.7 

12005440 417.4 417.4 417.4 417.4 417.4 417.4 417.4 417.4 

12005441 413.2 413.2 413.2 413.2 413.2 413.2 413.2 413.2 

12005442 411.9 411.9 411.9 411.9 411.9 411.9 411.9 411.9 

12005443 410.7 410.7 410.7 410.7 410.7 410.7 410.7 410.7 

12005444 409.4 409.4 409.4 409.4 409.4 409.4 409.4 409.4 

12005445 408.2 408.2 408.2 408.2 408.2 408.2 408.2 408.2 

12005446 406.9 406.9 406.9 406.9 406.9 406.9 406.9 406.9 

12005447 405.7 405.7 405.7 405.7 405.7 405.7 405.7 405.7 

12005448 404.4 404.4 404.4 404.4 404.4 404.4 404.4 404.4 

12005449 403.2 403.2 403.2 403.2 403.2 403.2 403.2 403.2 

* test specific length (2 rods)
128

12005501 0 0 0 1 0.0762 1

12005502 0 0 0 1 0.1524 48

12005503 0 0 0 1 0.0762 49

12005601 200010000 0 1 1 0.0762 1

12005602 200020000 10000 1 1 0.1524 48 

12005603 200490000 0 1 1 0.0762 49 

12005701 0 0.0 0.0 0.0 49

12005801 0.0 20.0 20.0 0.0 0.0 0.0 0.0 1.0 49

12005901 0.0 20.0 20.0 0.0 0.0 0.0 0.0 1.0 49

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

*

* heat structure thermal properties

*

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

20100100 tbl/fctn 1 1 * boron nitride

20100200 tbl/fctn 1 1 * kanthal

20100300 tbl/fctn 1 1 * ss-304

20100400 tbl/fctn 1 1 * ss-347

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

* conductivity

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

* boron nitride

20100101 300.0 25.16 

20100102 400.0 24.91 

20100103 500.0 24.67 

20100104 600.0 24.42 

20100105 700.0 24.18 

20100106 800.0 23.93 

20100107 900.0 23.69 

20100108 1000.0 23.44 

20100109 1100.0 23.19 

20100110 1200.0 22.95 

20100111 1300.0 22.70 

20100112 1400.0 22.46 

20100113 1500.0 22.21 

20100114 1600.0 21.97 

20100115 1700.0 21.72 

* kanthal + boron nitride

20100201 300.0 29.13 

20100202 400.0 29.61 

20100203 500.0 30.09 

20100204 600.0 30.58 

20100205 700.0 31.06 

20100206 800.0 31.54 

20100207 900.0 32.02 

20100208 1000.0 32.51 

20100209 1100.0 32.99 

20100210 1200.0 33.47 

20100211 1300.0 33.96 

20100212 1400.0 34.44 

20100213 1500.0 34.92 

20100214 1600.0 35.41 

20100215 1700.0 35.89 

* ss-304

20100301 300.0 12.97 

20100302 400.0 14.59 

20100303 500.0 16.21 
129

20100304 600.0 17.82 

20100305 700.0 19.44 

20100306 800.0 21.06 

20100307 900.0 22.68 

20100308 1000.0 24.30 

20100309 1100.0 25.91 

20100310 1200.0 27.53 

20100311 1300.0 29.15 

20100312 1400.0 30.77 

20100313 1500.0 32.39 

20100314 1600.0 34.00 

20100315 1700.0 35.62 

*ss-347

20100401 300.0 16.37 

20100402 400.0 17.10 

20100403 500.0 17.83 

20100404 600.0 18.55 

20100405 700.0 19.28 

20100406 800.0 20.01 

20100407 900.0 20.73 

20100408 1000.0 21.46 

20100409 1100.0 22.19 

20100410 1200.0 22.92 

20100411 1300.0 23.64 

20100412 1400.0 24.37 

20100413 1500.0 25.10 

20100414 1600.0 25.82 

20100415 1700.0 26.55 

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

* volumetric heat capacity

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

*boron nitride

20100151 300.0 1.80040e6

20100152 400.0 2.34650e6

20100153 500.0 2.79610e6

20100154 600.0 3.16050e6

20100155 700.0 3.45090e6

20100156 800.0 3.67820e6

20100157 900.0 3.85370e6

20100158 1000.0 3.98860e6

20100159 1100.0 4.09380e6

20100160 1200.0 4.18070e6

20100161 1300.0 4.26020e6

20100162 1400.0 4.34360e6

20100163 1500.0 4.44200e6

20100164 1600.0 4.56650e6

20100165 1700.0 4.72820e6

* kanthal + boron nitride

20100251 300.0 2.29400e6

20100252 400.0 2.92790e6

20100253 500.0 3.26520e6

20100254 600.0 3.50590e6

20100255 700.0 3.69620e6

20100256 800.0 3.85510e6

20100257 900.0 3.99240e6

20100258 1000.0 4.11360e6

20100259 1100.0 4.22260e6
130

20100260 1200.0 4.32180e6

20100261 1300.0 4.41300e6

20100262 1400.0 4.49750e6

20100263 1500.0 4.57640e6

20100264 1600.0 4.65030e6

20100265 1700.0 4.72010e6

* ss-304

20100351 300.0 3.61140e6

20100352 400.0 3.96460e6

20100353 500.0 4.14360e6

20100354 600.0 4.23160e6

20100355 700.0 4.28970e6

20100356 800.0 4.35670e6

20100357 900.0 4.45010e6

20100358 1000.0 4.56620e6

20100359 1100.0 4.68090e6

20100360 1200.0 4.75070e6

20100361 1300.0 4.71290e6

20100362 1400.0 4.48710e6

20100363 1500.0 3.97600e6

20100364 1600.0 3.06650e6

20100365 1700.0 1.63060e6

* ss-347

20100451 300.0 3.8513e6

20100452 400.0 3.9914e6

20100453 500.0 4.1316e6

20100454 600.0 4.2718e6

20100455 700.0 4.4119e6

20100456 800.0 4.5521e6

20100457 900.0 4.6922e6

20100458 1000.0 4.8324e6

20100459 1100.0 4.9725e6

20100460 1200.0 5.1127e6

20100461 1300.0 5.2528e6

20100462 1400.0 5.3930e6

20100463 1500.0 5.5332e6

20100464 1600.0 5.6733e6

20100465 1700.0 5.8135e6

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

*

* power table

*

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

* test specific power and decay curve

20220000 power 500 1.0 8.04952e5

20220001 0.0 1.00000 

20220002 3.6 0.98320 

20220003 8.1 0.95981 

20220004 15.8 0.92975 

20220005 23.6 0.90135 

20220006 41.4 0.85792 

20220007 55.8 0.82786 

20220008 76.9 0.79111 

20220009 98.1 0.76272 

20220010 125.8 0.72764 

20220011 162.5 0.69423 

20220012 202.5 0.66417 
131

20220013 244.7 0.63911 

20220014 303.6 0.61072 

20220015 339.2 0.59735 

20220016 391.4 0.57898 

20220017 451.4 0.56061 

20220018 503.6 0.54557 

20220019 546.9 0.53722 

20220020 592.5 0.52553 

20220021 636.9 0.51885 

20220022 679.2 0.50883 

20220023 729.2 0.50214 

20220024 771.4 0.49379 

20220025 798.1 0.49045 

20220026 818.1 0.48711 

20220027 819.2 0.35683 

20220028 820.3 0.23823 

20220029 821.4 0.12423 

20220030 829.9 0.00000 

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

*

* control variables

*

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

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

* cntrlvar-005 : core collapsed water level

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

20500100 wt-lvl1 sum 1.0 0.0 1

20500101 0.0 0.0381 voidf 200010000

20500102 0.0762 voidf 200020000

20500103 0.0762 voidf 200030000

20500104 0.0762 voidf 200040000

20500105 0.0762 voidf 200050000

20500106 0.0762 voidf 200060000

20500107 0.0762 voidf 200070000

20500108 0.0762 voidf 200080000

20500109 0.0762 voidf 200090000

20500110 0.0762 voidf 200100000

20500111 0.0762 voidf 200110000

20500112 0.0762 voidf 200120000

20500113 0.0762 voidf 200130000

20500114 0.0762 voidf 200140000

20500115 0.0762 voidf 200150000

20500116 0.0762 voidf 200160000

20500117 0.0762 voidf 200170000

20500118 0.0762 voidf 200180000

20500119 0.0762 voidf 200190000

20500120 0.0762 voidf 200200000

*

20500200 wt-lvl2 sum 1.0 0.0 1

20500201 0.0 0.0762 voidf 200210000 

20500202 0.0762 voidf 200220000 

20500203 0.0762 voidf 200230000 

20500204 0.0762 voidf 200240000 

20500205 0.0762 voidf 200250000 

20500206 0.0762 voidf 200260000 

20500207 0.0762 voidf 200270000 

20500208 0.0762 voidf 200280000 
132

20500209 0.0762 voidf 200290000 

20500210 0.0762 voidf 200300000 

20500211 0.0762 voidf 200310000 

20500212 0.0762 voidf 200320000 

20500213 0.0762 voidf 200330000 

20500214 0.0762 voidf 200340000 

20500215 0.0762 voidf 200350000 

20500216 0.0762 voidf 200360000 

20500217 0.0762 voidf 200370000 

20500218 0.0762 voidf 200380000 

20500219 0.0762 voidf 200390000 

20500220 0.0762 voidf 200400000 

*

20500300 wt-lvl3 sum 1.0 0.0 1

20500301 0.0 0.0762 voidf 200410000 

20500302 0.0762 voidf 200420000 

20500303 0.0762 voidf 200430000 

20500304 0.0762 voidf 200440000

20500305 0.0762 voidf 200450000 

20500306 0.0762 voidf 200460000 

20500307 0.0762 voidf 200470000 

20500308 0.0762 voidf 200480000 

20500309 0.0381 voidf 200490000

*

20500500 wt-level sum 1.0 0.0 1

20500501 0.0 1.0000 cntrlvar 001 

20500502 1.0000 cntrlvar 002 

20500503 1.0000 cntrlvar 003 

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

* cntrlvar-011~022 : void fraction at every 12 inches

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

* 0 ~ 1 ft

20501100 voidg1 sum 0.25 0.0 1

20501101 0.0 0.5 voidg 200010000

20501102 1.0 voidg 200020000

20501103 1.0 voidg 200030000

20501104 1.0 voidg 200040000

20501105 0.5 voidg 200050000

* 1 ~ 2 ft

20501200 voidg2 sum 0.25 0.0 1

20501201 0.0 0.5 voidg 200050000

20501202 1.0 voidg 200060000

20501203 1.0 voidg 200070000

20501204 1.0 voidg 200080000

20501205 0.5 voidg 200090000

* 2 ~ 3 ft

20501300 voidg3 sum 0.25 0.0 1

20501301 0.0 0.5 voidg 200090000

20501302 1.0 voidg 200100000

20501303 1.0 voidg 200110000

20501304 1.0 voidg 200120000

20501305 0.5 voidg 200130000

* 3 ~ 4 ft

20501400 voidg4 sum 0.25 0.0 1

20501401 0.0 0.5 voidg 200130000

20501402 1.0 voidg 200140000

20501403 1.0 voidg 200150000
133

20501404 1.0 voidg 200160000

20501405 0.5 voidg 200170000

* 4 ~ 5 ft

20501500 voidg5 sum 0.25 0.0 1

20501501 0.0 0.5 voidg 200170000

20501502 1.0 voidg 200180000

20501503 1.0 voidg 200190000

20501504 1.0 voidg 200200000

20501505 0.5 voidg 200210000

* 5 ~ 6 ft

20501600 voidg6 sum 0.25 0.0 1

20501601 0.0 0.5 voidg 200210000

20501602 1.0 voidg 200220000

20501603 1.0 voidg 200230000

20501604 1.0 voidg 200240000

20501605 0.5 voidg 200250000

* 6 ~ 7 ft

20501700 voidg7 sum 0.25 0.0 1

20501701 0.0 0.5 voidg 200250000

20501702 1.0 voidg 200260000

20501703 1.0 voidg 200270000

20501704 1.0 voidg 200280000

20501705 0.5 voidg 200290000

* 7 ~ 8 ft

20501800 voidg8 sum 0.25 0.0 1

20501801 0.0 0.5 voidg 200290000

20501802 1.0 voidg 200300000

20501803 1.0 voidg 200310000

20501804 1.0 voidg 200320000

20501805 0.5 voidg 200330000

* 8 ~ 9 ft

20501900 voidg9 sum 0.25 0.0 1

20501901 0.0 0.5 voidg 200330000

20501902 1.0 voidg 200340000

20501903 1.0 voidg 200350000

20501904 1.0 voidg 200360000

20501905 0.5 voidg 200370000

* 9 ~ 10 ft

20502000 voidg10 sum 0.25 0.0 1

20502001 0.0 0.5 voidg 200370000

20502002 1.0 voidg 200380000

20502003 1.0 voidg 200390000

20502004 1.0 voidg 200400000

20502005 0.5 voidg 200410000

* 10 ~ 11 ft

20502100 voidg11 sum 0.25 0.0 1

20502101 0.0 0.5 voidg 200410000

20502102 1.0 voidg 200420000

20502103 1.0 voidg 200430000

20502104 1.0 voidg 200440000

20502105 0.5 voidg 200450000

* 11 ~ 12 ft

20502200 voidg12 sum 0.25 0.0 1

20502201 0.0 0.5 voidg 200450000

20502202 1.0 voidg 200460000

20502203 1.0 voidg 200470000

20502204 1.0 voidg 200480000
134

20502205 0.5 voidg 200490000

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

* cntrlvar-031~43 : wall temp - sat. temp 

* at every measurement location

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

* 1 ft

20503100 dtemp1 sum 1.0 0.0 1

20503101 0.0 1.0 httemp 200100508

20503102 -1.0 sattemp 200050000

* 2 ft

20503200 dtemp2 sum 1.0 0.0 1

20503201 0.0 1.0 httemp 200100908

20503202 -1.0 sattemp 200090000

* 3 ft

20503300 dtemp3 sum 1.0 0.0 1

20503301 0.0 1.0 httemp 200101308

20503302 -1.0 sattemp 200130000

* 4 ft

20503400 dtemp4 sum 1.0 0.0 1

20503401 0.0 1.0 httemp 200101708

20503402 -1.0 sattemp 200170000

* 5 ft

20503500 dtemp5 sum 1.0 0.0 1

20503501 0.0 1.0 httemp 200102108

20503502 -1.0 sattemp 200210000

* 6 ft

20503600 dtemp6 sum 1.0 0.0 1

20503601 0.0 1.0 httemp 200102508

20503602 -1.0 sattemp 200250000

* 7 ft

20503700 dtemp7 sum 1.0 0.0 1

20503701 0.0 1.0 httemp 200102908

20503702 -1.0 sattemp 200290000

* 8 ft

20503800 dtemp8 sum 1.0 0.0 1

20503801 0.0 1.0 httemp 200103308

20503802 -1.0 sattemp 200330000

* 9 ft

20503900 dtemp9 sum 1.0 0.0 1

20503901 0.0 1.0 httemp 200103708

20503902 -1.0 sattemp 200370000

* 10 ft

20504000 dtemp10 sum 1.0 0.0 1

20504001 0.0 1.0 httemp 200104108

20504002 -1.0 sattemp 200410000

* 11 ft

20504100 dtemp11 sum 1.0 0.0 1

20504101 0.0 1.0 httemp 200104508

20504102 -1.0 sattemp 200450000

* 12 ft

20504200 dtemp12 sum 1.0 0.0 1

20504201 0.0 1.0 httemp 200104908

20504202 -1.0 sattemp 200490000

* 6.5 ft

20504300 dtemp65 sum 1.0 0.0 1

20504301 0.0 1.0 httemp 200102708

20504302 -1.0 sattemp 200270000
135

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

* cntrlvar-051~62 : heat transfer coefficient 

* at every measurement location

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

* 1 ft

20505100 htc1 div 1.0 1.0 1 

20505101 cntrlvar 031 htrnr 200100501

* 2 ft

20505200 htc2 div 1.0 1.0 1 

20505201 cntrlvar 032 htrnr 200100901

* 3 ft

20505300 htc3 div 1.0 1.0 1 

20505301 cntrlvar 033 htrnr 200101301

* 4 ft

20505400 htc4 div 1.0 1.0 1 

20505401 cntrlvar 034 htrnr 200101701

* 5 ft

20505500 htc5 div 1.0 1.0 1 

20505501 cntrlvar 035 htrnr 200102101

* 6 ft

20505600 htc6 div 1.0 1.0 1 

20505601 cntrlvar 036 htrnr 200102501

* 7 ft

20505700 htc7 div 1.0 1.0 1 

20505701 cntrlvar 037 htrnr 200102901

* 8 ft

20505800 htc8 div 1.0 1.0 1 

20505801 cntrlvar 038 htrnr 200103301

* 9 ft

20505900 htc9 div 1.0 1.0 1 

20505901 cntrlvar 039 htrnr 200103701

* 10 ft

20506000 htc10 div 1.0 1.0 1 

20506001 cntrlvar 040 htrnr 200104101

* 11 ft

20506100 htc11 div 1.0 1.0 1 

20506101 cntrlvar 041 htrnr 200104501

* 12 ft

20506200 htc12 div 1.0 1.0 1 

20506201 cntrlvar 042 htrnr 200104901

* 6.5 ft

20506300 htc65 div 1.0 1.0 1 

20506301 cntrlvar 043 htrnr 200102701

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

* cntrlvar-071~82 : differential pressure 

* between every measurement location

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

* 0 ~ 1 ft

20507100 dp01 sum 1.0 0.0 1

20507101 0.0 1.0 p 200010000

20507102 -1.0 p 200050000

* 1 ~ 2 ft

20507200 dp12 sum 1.0 0.0 1

20507201 0.0 1.0 p 200050000

20507202 -1.0 p 200090000

* 2 ~ 3 ft

20507300 dp23 sum 1.0 0.0 1
136

20507301 0.0 1.0 p 200090000

20507302 -1.0 p 200130000

* 3 ~ 4 ft

20507400 dp34 sum 1.0 0.0 1

20507401 0.0 1.0 p 200130000

20507402 -1.0 p 200170000

* 4 ~ 5 ft

20507500 dp45 sum 1.0 0.0 1

20507501 0.0 1.0 p 200170000

20507502 -1.0 p 200210000

* 5 ~ 6 ft

20507600 dp56 sum 1.0 0.0 1

20507601 0.0 1.0 p 200210000

20507602 -1.0 p 200250000

* 6 ~ 7 ft

20507700 dp67 sum 1.0 0.0 1

20507701 0.0 1.0 p 200250000

20507702 -1.0 p 200290000

* 7 ~ 8 ft

20507800 dp78 sum 1.0 0.0 1

20507801 0.0 1.0 p 200290000

20507802 -1.0 p 200330000

* 8 ~ 9 ft

20507900 dp89 sum 1.0 0.0 1

20507901 0.0 1.0 p 200330000

20507902 -1.0 p 200370000

* 9 ~ 10 ft

20508000 dp910 sum 1.0 0.0 1

20508001 0.0 1.0 p 200370000

20508002 -1.0 p 200410000

* 10 ~ 11 ft

20508100 dp1011 sum 1.0 0.0 1

20508101 0.0 1.0 p 200410000

20508102 -1.0 p 200450000

* 11 ~ 12 ft

20508200 dp1112 sum 1.0 0.0 1

20508201 0.0 1.0 p 200450000

20508202 -1.0 p 200490000

* 0 ~ 12 ft

20508300 dp012 sum 1.0 0.0 1

20508301 0.0 1.0 p 200010000

20508302 -1.0 p 200490000

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

* cntrlvar-110 : liquid carry-over fraction

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

20510100 flowin mult 0.0155565 0.0 1

20510101 voidfj 165000000

20510102 rhofj 165000000

20510103 velfj 165000000

*

20510200 floin integral 1.0 0.0 1

20510201 cntrlvar 101

* add small no. to avoid dividing by zero

20510300 floina sum 1.0 0.0 1

20510301 1.e-20 1.0 cntrlvar 102

*

20510400 flowot mult 0.0155565 0.0 1
137

20510401 voidfj 250000000

20510402 rhofj 250000000

20510403 velfj 250000000

*

20510500 floot integral 1.0 0.0 1

20510501 cntrlvar 104

*

20511000 carryf div 1.0 1.0 1 

20511001 cntrlvar 103 cntrlvar 105

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

* cntrlvar-200 : total power

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

20520000 power function 1.0 0.0 1

20520001 time 0 200

*

.