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145 Pages·2013·3.76 MB·English

AN ABSTRACT OF THE THESIS OF
Brian Todd Hallee for the degree of Master of Science in Nuclear Engineering presented
on March 5, 2013.
Title: Feed-and-Bleed Transient Analysis of OSU APEX Facility using the Modern
Code Scaling, Applicability, and Uncertainty Method
Abstract approved:
Qiao Wu
The nuclear industry has long relied upon bounding parametric analyses in predicting
the safety margins of reactor designs undergoing design-basis accidents. These methods
have been known to return highly-conservative results, limiting the operating conditions
of the reactor. The Best-Estimate Plus Uncertainty (BEPU) method using a modern-
ized version of the Code-Scaling, Applicability, and Uncertainty (CSAU) methodology
has been applied to more accurately predict the safety margins of the Oregon State Uni-
versity Advanced Plant Experiment (APEX) facility experiencing a Loss-of-Feedwater
Accident (LOFA). The statistical advantages of the Bayesian paradigm of probability
was utilized to incorporate prior knowledge when determining the analysis required to
justify the safety margins. RELAP5 Mod 3.3 was used to accurately predict the thermal-
hydraulics of a primary Feed-and-Bleed response to the accident using assumptions to
accompany the lumped-parameter calculation approach. A novel coupling of thermal-
hydraulic and statistical software was accomplished using the Symbolic Nuclear Analysis
Package (SNAP). Uncertainty in Peak Cladding Temperature (PCT) was calculated at
the 95/95 probability/confidence levels under a series of four separate sensitivity studies.
c
Copyright by Brian Todd Hallee
March 5, 2013
All Rights Reserved
Feed-and-Bleed Transient Analysis of OSU APEX Facility using the
Modern Code Scaling, Applicability, and Uncertainty Method
by
Brian Todd Hallee
A THESIS
submitted to
Oregon State University
in partial fulfillment of
the requirements for the
degree of
Master of Science
Presented March 5, 2013
Commencement June 2013
Master of Science thesis of Brian Todd Hallee presented on March 5, 2013.
APPROVED:
Major Professor, representing Nuclear Engineering
Head of the Department of Nuclear Engineering and Radiation Health Physics
Dean of the Graduate School
I understand that my thesis will become part of the permanent collection of Oregon
State University libraries. My signature below authorizes release of my thesis to any
reader upon request.
Brian Todd Hallee, Author
ACKNOWLEDGEMENTS
I wish to begin in acknowledging my indebtedness to my primary advisor Dr. Qiao Wu
for blessing me with a multitude of avenues for learning and succeeding in this area of
engineering, and for allowing me complete creative control in my path to completion
of this degree. The professional development I have experienced under his oversight is
unmatched by any previous mentor, and for that I wish to express my thankfulness.
I also wish to acknowledge the high-caliber colleagues I have been given the op-
portunity to work with in my short time at OSU. These include Jeffrey Luitjens, Hu
Luo, Chengcheng Deng, and Weili Liu. I will cherish the constructive criticism and co-
operative learning I have received from all of them as I transition into the professional
workforce.
The valuable feedback garnered from my thesis committee, including Dr. Andrew
Klein, Dr. Kent Welter, and Dr. Albert Stetz is greatly appreciated. I sincerely appreci-
ate the time that was taken from these busy schedules to enable a successful culmination
of my thesis.
I would like to recognize and thank my parents, Todd and Vicki, whose love and
support have given me the courage and perseverance to move thousands of miles to chase
my dreams.
Finally, I would like to acknowledge my wife Sarah, who continues to support my
sometimes overbearing work ethic and bring balance to my life.
TABLE OF CONTENTS
Page
1 Introduction 1
1.1 Research Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Method of Analysis and Limitations . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Overview of the Following Chapters . . . . . . . . . . . . . . . . . . . . . . 4
2 Survey of Relevant Literature 6
2.1 History of Best Estimate Plus Uncertainty Quantification . . . . . . . . . . 6
2.2 Development of the Code Scaling, Applicability, and Uncertainty Method . 7
2.3 Code Validation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.4 International and Commercial Alternatives to CSAU . . . . . . . . . . . . . 12
2.4.1 Gesellschat Fur Anlagen-und Reaktorsicherheit . . . . . . . . . . . 12
2.4.2 Automated Statistical Treatment of Uncertainty Method . . . . . 13
2.4.3 Uncertainty Method based on Accuracy Extrapolation . . . . . . . 13
2.4.4 Integrated Methodology on Thermal Hydraulics Uncertainty Anal-
ysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.5 Forward Uncertainty Propagation . . . . . . . . . . . . . . . . . . . . . . . . 14
2.5.1 Parametric Response Surfaces . . . . . . . . . . . . . . . . . . . . 15
2.5.2 The Wilks Method . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.5.3 Binomial Bayesian Method . . . . . . . . . . . . . . . . . . . . . . 19
2.6 Code Scaling Capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.7 Applications of CSAU to LWR Transients . . . . . . . . . . . . . . . . . . . 24
2.7.1 Technical Program Group CSAU Proof-of-Concept Analysis . . . . 24
2.7.2 Uncertainty and Sensitivity Analysis of LSTF 10% Hot-leg Break . 30
3 Oregon State University Advanced Plant Experiment 34
3.1 Overview of APEX Design and Implementation . . . . . . . . . . . . . . . . 34
3.1.1 Introduction and Scaling . . . . . . . . . . . . . . . . . . . . . . . 34
3.1.2 Instrumentation and Component Descriptions . . . . . . . . . . . . 35
4 Feed and Bleed Cooling of Pressurized Water Reactors 38
4.1 Theory of Feed and Bleed Method . . . . . . . . . . . . . . . . . . . . . . . 38
4.2 APEX Feed and Bleed Implementation . . . . . . . . . . . . . . . . . . . . . 41
4.2.1 Passive Feed and Bleed . . . . . . . . . . . . . . . . . . . . . . . . 41
4.2.2 Quasi-Steady-state Operation of APEX Feed-and-Bleed . . . . . . 44
TABLE OF CONTENTS (Continued)
Page
5 Phenomenon Identification and Ranking Process 47
5.1 OSU APEX1000 Feed-and-bleed PIRT . . . . . . . . . . . . . . . . . . . . . 49
5.1.1 Primary Coolant Parameters . . . . . . . . . . . . . . . . . . . . . 49
5.1.2 Core Heater Rod Parameters . . . . . . . . . . . . . . . . . . . . . 51
5.1.3 Reactor Cooling System Component Parameters . . . . . . . . . . 53
5.1.4 Secondary Fluid Parameters . . . . . . . . . . . . . . . . . . . . . 54
5.1.5 Chemical and Volume Control System Parameters . . . . . . . . . 55
5.1.6 Simulation-driven Parameters . . . . . . . . . . . . . . . . . . . . . 55
5.2 Primary Response Functions . . . . . . . . . . . . . . . . . . . . . . . . . . 58
6 Overview of Virtual APEX Nodalization and Job Stream 60
6.1 APEX Rev. 2b RELAP5 Mod 3.3 Model . . . . . . . . . . . . . . . . . . . 60
6.1.1 Model Revisions Commensurate with a Feed-and-Bleed Test . . . 62
6.1.2 RELAP5 Applicability and Limitations . . . . . . . . . . . . . . . 64
6.1.3 Qualification of APEX RELAP5 Nodalization . . . . . . . . . . . 65
6.2 Symbolic Nuclear Analysis Package Job Stream . . . . . . . . . . . . . . . . 67
6.3 Preliminary Sensitivity Study . . . . . . . . . . . . . . . . . . . . . . . . . . 70
6.4 Derivation of Sampling Requirements . . . . . . . . . . . . . . . . . . . . . . 73
7 Feed-and-Bleed Simulation Results 78
7.1 95/95 Results: CVSP Delay Before 900 seconds . . . . . . . . . . . . . . . . 78
7.1.1 Response Functions . . . . . . . . . . . . . . . . . . . . . . . . . . 78
7.1.2 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
7.2 CVSP Delay Between 900 and 1,100 seconds . . . . . . . . . . . . . . . . . . 92
7.2.1 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
7.2.2 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
7.3 CVS Injection Occurring After 1,100 seconds . . . . . . . . . . . . . . . . . 99
7.4 Long-term Feed-and-Bleed Analysis at Nominal State . . . . . . . . . . . . 100
7.4.1 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
7.4.2 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
8 Conclusion 108
8.1 Success of Modern CSAU . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
8.2 Uncertainty Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
TABLE OF CONTENTS (Continued)
Page
8.3 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Bibliography 111
Appendices 121
A Random Input Sampling and the Wilks Method . . . . . . . . . . . . . . . . 122
B Raw Mathematica Input Needed for Iterative Bayesian Updating . . . . . . 130
LIST OF FIGURES
Figure Page
2.1 The traditional 14-step application of CSAU to a reactor transient. . . . . 10
2.2 The code as a black box, which receives random inputs and receives a
statistical set of outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.3 The ten-step CSAU process for determining biases attributed to scaling
distortion and deficiencies. . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.4 Comparison between LOFT experimental PCT histogram and TRAC PCT
PDF results with and without bias.[38] . . . . . . . . . . . . . . . . . . . . 29
3.1 APEX Facility Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.1 A typical operating map for optimal steady state feed-and-bleed operation
[15] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4.2 Detail of CVS/PRHR HX flow connnection to SG-2 lower channel head. [1] 43
4.3 Upper and lower operating pressure bounds for a quasi-steady-state APEX
feed-and-bleed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.1 Stratified Flow in Downcomer . . . . . . . . . . . . . . . . . . . . . . . . . 51
6.1 Volume nodalization of the APEX1000 facility in RELAP5 Mod 3.3 . . . . 61
6.2 Primary Loop Pressure (Steady-State RELAP5 Results) . . . . . . . . . . 66
6.3 SNAP Parametric Job Stream for Feed-and-bleed Uncertainty Analysis . . 69
7.1 Distribution of fluid temperatures at the downcomer-to-lower plenum con-
nections below cold legs 1-4. (Lines shown are upper 95th, mean, and
lower 95th percentiles) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
7.2 Continuous peak cladding temperature measured at the radial center-line
of the heat structure representing peak axial power. . . . . . . . . . . . . . 85
7.3 Uncertainty in mass flow rate from the downcomer (negative direction) to
the core region (positive direction). . . . . . . . . . . . . . . . . . . . . . . 86