HEFT-DELFIC Fallout Particle Size Predictions (comparison) - USAF

150 Pages·2005·3.463 MB·English

A COMPARISON OF THE HEFT SUBSURFACE
AND DELFIC PARTICLE SIZE DISTRIBUTIONS

AND EFFECTS IN HPAC

THESIS

Eric T. Skaar, First Lieutenant, USAF

AFIT/GNE/ENP/05-13

DEPARTMENT OF THE AIR FORCE
AIR UNIVERSITY

AIR FORCE INSTITUTE OF TECHNOLOGY

Wright-Patterson Air Force Base, Ohio

APPROVED FOR PUBLIC RELEASE: DISTRIBUTION IS UNLIMITED
The views expressed in this thesis are those of the author and do not reflect the official
policy or position of the United States Air Force, Department of Defense, or the United
States Government.
AFIT/GNE/ENP/05-13

A COMPARISON OF THE HEFT SUBSURFACE

AND DELFIC PARTICLE SIZEDISTRIBUTIONS

AND EFFECTS IN HPAC

THESIS

Presented to the Faculty

Department of Engineering Physics

Graduate School of Engineering and Management

Air Force Institute of Technology

Air University

Air Education and Training Command

In Partial Fulfillment of the Requirements for the

Degree of Master of Science in Nuclear Engineering

Eric T. Skaar, BS

First Lieutenant, USAF

March 2005

APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED.

AFIT/GNE/ENP/05-13
Abstract
The Heft subsurface three component lognormal fallout particle size distribution
is compared and contrasted with the single lognormal fallout particle size distribution
used by the Defense Land Fallout Interpretive Code (DELFIC). Comparison of the two
distributions is accomplished with results from the AFIT smear code and the Hazard
Prediction and Assessment Capability (HPAC). The effect of the distributions is
explored in HPAC for varying yield weapons, varying surfaces, precipitation conditions,
varying wind effects and varying dose rate times. The results from the two distributions
are quantitatively compared using the concepts of grounded source normalization
constant and the rate at which activity is being deposited on the ground everywhere at
time t.
The Heft subsurface three component lognormal fallout particle size distribution
results in significantly less activity on the ground than does the DELFIC single lognormal
particle size distribution. The grounded source normalization constant resulting from the
Heft distribution is up to three times smaller than that observed when using the DEFLIC
distribution.

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Acknowledgments

I would like to thank my advisor, Dr. Charles J. Bridgman for his time, criticism,
encouragement and humor. It has been an honor and a privilege to work under his
tutelage. I’d also like to thank the members of my thesis committee, Lt. Col Vincent
Jodoin and Lt Col Steve Fiorino for their feedback.
I am also indebted to all of those who went out of their way to help me,
particularly Dr. Joseph T. McGahan and Major D. Brent Morris. Without their insight
and assistance I could not have completed this thesis. A special thanks also to Major
Steven Weber who helped me in the writing and editing of this thesis.

Eric T. Skaar

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Table of Contents
Page
Abstract ......................................................................................................................iv

Acknowledgements........................................................................................................v

List of Figures ..........................................................................................................viii

List of Tables ............................................................................................................xii

I. Introduction ............................................................................................................1

Motivation...............................................................................................................1
Background.............................................................................................................1
Problem...................................................................................................................2
Scope.......................................................................................................................3
General Approach...................................................................................................3

II. Literature Review...................................................................................................4

Physics of Fallout Formation.................................................................................4
Description of the DELFIC Particle Distribution..................................................7
Description of the Heft Subsurface Particle Distribution......................................9
Comparison of the Heft Subsurface Crystalline Distribution with the Baker
Airburst Distribution............................................................................................10
Comparison of the Heft Three-Component Subsurface Distribution with the
DELFIC Surface Distribution..............................................................................11
HPAC Overview..................................................................................................12
Cloud Rise in Newfall/DELFIC...........................................................................13
Activity Calculation in DELFIC..........................................................................15
Basic Information Concerning SCIPUFF............................................................19

III. Methodology 23

Introduction to Source Normalization Constant, k..............................................23
Method for Calculating Source Normalization Constant from HPAC Output....24
Introduction to g(t)...............................................................................................25
Method for Calculating the Function g(t) from HPAC Outputs..........................27
General Information Concerning HPAC Runs....................................................27

IV. Results and Data Comparison.............................................................................31

Results of the AFIT Smear Code for DELFIC Surface and Heft Subsurface
Particle Distributions...........................................................................................31
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A Comparison of the DELFIC and Heft Subsurface Particle Distributions for
Varying Yields and Resolutions..........................................................................39
Variation in the Grounded Source Normalization Constant When Computed
from Different Late Time Dose Rates.................................................................48

V. Interaction of Particle Size Distribution with Other Variable Parameters in
HPAC...................................................................................................................58

Effects of Varying Surfaces.................................................................................58
Effects of Rain Out..............................................................................................67
Effects of Different Constant Wind Speeds for DELFIC and Heft Three
Component Particle Distributions........................................................................76

VI. Research Summary and Conclusions..................................................................81

Research Summary..............................................................................................81
Conclusions..........................................................................................................81
Recommendations for Future Research...............................................................83

Glossary .....................................................................................................................86

Appendix A. Converting a Log distribution to a Ln Distribution ...........................89
10

Appendix B: Summarization of Freiling Ratios and Heft Distributions......................91

Appendix C. Summary of Surface Effects in SCIPUFF ..........................................105

Appendix D. Code for Calculating g(t) ....................................................................111

Appendix E. Code for Calculating the Effective Source Normalization Constant ..122

Bibliography ............................................................................................................134

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List of Figures

Figure Page

1. DELFIC Number Distribution...........................................................................8
2. DELFIC Mass Distribution................................................................................8
3. Volume Distribution for Heft Subsurface Crystalline and Baker Airburst......11
4. Comparison of DELFIC and Heft Three-Component Mass Distributions......12
5. HPAC Stages (11:4-1).....................................................................................13
6. Nuclear Weapon Parameters Used in HPAC Runs..........................................28
7. Fixed Wind Parameters Used in HPAC Runs..................................................29
8. General Weather Parameters Used in HPAC Runs.........................................29
9. Typical HPAC Dose Rate Contour with Default Dose Rate Values Shown
in Legend.........................................................................................................30

10. AFIT Smear Code 30 Day Dose Contour for 1kt Surface Burst using
DELFIC Distribution with 10kph Constant wind (Units in Roentgen)...........33

11. AFIT Smear Code 30 Day Dose Contour for 1kt Surface Burst using Heft
Subsurface Distrubution with 10kph Constant Wind (Units in Roentgen)......34

12. AFIT Smear Code 30 Day Dose Contour for 1kt Surface Burst using
Crystalline Distribution with 10kph Constant Wind (Units in Roentgen).......35

13. AFIT Smear Code 30 Day Dose Contour for 1kt Surface Burst using Glass
Distribution with 10kph Constant Wind (Units in Roentgen).........................36

14. AFIT Smear Code 30 Day Dose Rate for 1kt Surface Burst using the Local
Distribution with 10kph Constant Wind (Units in Roentgen).........................37

15. G(t) Comparison for 1kt Surface Burst using Heft Subsurface and DELFIC
Particle Distributions in AFIT Smear Code.....................................................38

16. Altitudes of the Stabilized Cloud Top and Cloud Bottom Based on Yield
for Surface Bursts (9: 431)...............................................................................39

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17. HPAC 4.03 Dose Rate Contour for 1kt Surface Burst at 12.75 Hours............40
18. HPAC 4.04 Dose Rate Contour for 1kt Surface Burst at 12.25 Hours............40
19. HPAC 4.03 Ground Zero Dose Rate Contour for 1kt Surface Burst at 12
Hours................................................................................................................41

20. HPAC 4.04 Ground Zero Dose Rate Contour for 1kt Surface Burst at 12
Hours................................................................................................................42

21. g(t) for 1kt Surface Burst in HPAC 4.03 and 4.04...........................................43
22. HPAC 4.03 Dose Rate Contour for 10kt Surface Burst at 23 Hours...............45
23. HPAC 4.04 Dose Rate for 10kt Surface Burst at 22 Hours.............................45
24. HPAC 4.03 Dose Rate Contour for 100kt Surface Burst at 48 Hours.............46
25. HPAC 4.04 Dose Rate Contour for 100kt Surface Burst at 48 Hours.............47
26. Dose Rate vs. Time (Dashed Line Represents the Way-Wigner
Approximation) (9:392)...................................................................................49

27. HPAC 4.03 Dose Rate Contour for 100kt Surface Burst at 8 Hours...............50
28. HPAC 4.03 Dose Rate Contour for 100kt Surface Burst at 16 Hours.............50
29. HPAC 4.03 Dose Rate Contour for 100kt Surface Burst at 24 Hours.............50
30. HPAC 4.03 Dose Rate for 100kt Surface Burst at 32 Hours...........................50
31. HPAC 4.03 Dose Rate Contour for 100kt Surface Burst at 40 Hours.............50
32. HPAC 4.03 Dose Rate Contour for 100kt Surface Burst at 48 Hours.............50
33. HPAC 4.04 Dose Rate Contour for 100kt Surface Burst at 8 Hours...............51
34. HPAC 4.04 Dose Rate Contour for 100kt Surface Burst at 16 Hours.............51
35. HPAC 4.04 Dose Rate Contour for 100kt Surface Burst at 24 Hours.............51
36. HPAC 4.04 Dose Rate Contour for 100kt Surface Burst at 32 Hours.............51
37. HPAC 4.04 Dose Rate Contour for 100kt Surface Burst at 40 Hours.............51
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