vii
TABLE OF CONTENTS
CHAPTER
1
2
TITLE
PAGE
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENT
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
x
LIST OF FIGURES
xi
LIST OF SYMBOLS AND ACRONYMS
xiv
LIST OF APPENDICES
xvi
INTRODUCTION
1.1
Background of research
1
1.2
Historical Review of Neutron Radiography
3
1.3
Research Objectives
6
1.4
Rational for Research
6
1.5
Research Scope
7
1.6
Organization of Thesis
7
LITERATURE REVIEW
2.1
Neutron Radiography
8
2.1.1 Principle of neutron radiography
11
2.1.2 Neutron sources
12
viii
2.2
2.1.2.1 Accelerator
12
2.1.2.2 Radioisotopes
13
2.1.2.3 Nuclear reactor
14
The Monte Carlo N-Particle Code Version 5
15
2.2.1 The Monte Carlo Method
16
2.2.2 Neutron Physics in MCNP5
17
Transfer Function for Imaging System
18
2.3.1 Edge and Line Spread Function
18
2.3.2 Two Dimensional Fourier Transform
20
2.4
Modulation Transfer Function
21
2.5
Neutron Radiographic Facilities at the Malaysian
22
2.3
Nuclear Agency (Nuclear Malaysia)
2.6
3
Previous study on NUR-2 system
24
METHODOLOGY
3.1
Introduction to Sample
26
3.2
Geometry of Exposure
27
3.3
Monte Carlo Simulations
29
3.3.1 Input file
29
3.3.2 Output
30
3.3.3 Simulations in MCNP5
31
Experimental confirmation of the MCNP
32
3.4
simulation
4
3.4.1 Experimental Procedure
33
3.5
Edge Image Processing
37
3.6
MTF measurement and calculation
39
RESULTS AND DISCUSSION
4.1
4.2
MCNP simulation results
42
4.1.1 Cadmium without scattering material
43
4.1.2 Cadmium with scattering material
45
Experimental results
47
4.2.1 Cadmium without scattering material
47
ix
4.3
5
4.2.2 Cadmium with scattering material
51
Comparison of MCNP simulation and experiment
56
CONCLUSION AND RECOMMENDATION
5.1
Conclusion
59
5.2
Recommendation
61
REFERENCES
62
APPENDICES
65
x
LIST OF TABLES
TABLE NO.
TITLE
PAGE
2.1
Classification of neutron by energy
10
3.1
Radiographic image quality
35
4.1
Estimation of spatial frequency at MTF20% from
simulation and experiment for each thickness of
58
cadmium
4.2
Estimation of FWHM from simulation and
experiment for each thickness of cadmium
58
xi
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
2.1
Mass absorption coefficients for the elements for
both thermal neutrons and X-rays
9
2.2
Schematic sketch for neutron radiography
11
2.3
Random history of a neutron incident on a slab of
material that can undergo fission
17
2.4
A line input δ(x1)
19
2.5
Representation of an ideal edge profile
21
2.6
Derivation of the MTF from the edge response
curve
2.7
22
Reactor TRIGA MARK II beamports and thermal
column arrangements
23
2.8
Layout of NUR-2 facility
24
2.9
Neutron collimator arrangement
24
3.1
Cadmium foil
27
3.2
Diagram of knife-edge experiment
28
3.3
MCNP input file structure
29
3.4
The used Monte Carlo model for calculation of the
ESF
3.5
Setup
32
for
knife-edge
measurement
without
scattering material
3.6
33
Neutron radiography setup in NUR-2 exposure
room
34
xii
3.7
Characteristic of NUR-2 measured by measured
ASTM beam purity indicator
35
3.8
DR3000 digital radiograph film digitisation system
36
3.9
Setup for knife-edge measurement with scattering
material
3.10
36
(a) Surface plot of ESF profile direct from
TECPLOT file
37
(b) Cropped ESF profile from TECPLOT file
37
3.11
Edge profile retrieval using Isee! Software
38
3.12
Cropped knife-edge image of cadmium
39
3.13
Operational framework of the MTF measurement
and calculation
40
3.14
FWHM determination
41
4.1
Comparison of MCNP simulation result of (a) Edge
spread function, (b) Line spread function and (c)
Modulation transfer function for three different
thickness of cadmium without scattering material
4.2
44
Comparison of MCNP simulation result of (a) Edge
spread function, (b) Line spread function and (c)
Modulation transfer function for three different
thickness of cadmium with scattering material
46
4.3
Neutron radiography image for cadmium knife-edge
47
4.4
Cropped knife-edge image of cadmium
48
4.5
Comparison of experimental result of (a) Edge
spread function and (b) Line spread function for
three different thickness of cadmium without
scattering material
4.6
49
Comparison of experimental result of (a) raw and
(b) smoothed modulation transfer function for three
different thickness of cadmium without scattering
material
4.7
50
Neutron radiography image for cadmium knife-edge
with scatterer
51
xiii
4.8
Cropped knife-edge image of cadmium with
scatterer
4.9
52
Comparison of experimental result of (a) Edge
spread function and (b) Line spread function for
three different thicknesses of cadmium with
scattering material
4.10
53
Comparison of experimental result of (a) Edge
spread function and (b) Line spread function for
three different thicknesses of cadmium with
scattering material
4.11
55
MTF comparison of MCNP simulation and
experiment for (a) 1 mm, (b) 2 mm and (c) 3 mm
thick of cadmium for all cases
57
xiv
LIST OF SYMBOLS AND ACRONYMS
eV
-
Electron volt
kW
-
Kilowatt
R
-
Röentgen
n
-
Neutron
cm
-
Centimetre
mm
-
Millimetre
µm
-
Micrometre
s
-
Second
I
-
Transmitted intensity
I0
-
Incident intensity
Ʃ
-
Macroscopic absorption cross section
d
-
Thickness of the sample
Sb-Be
-
Antimony Beryllium
Am-Be
-
Americium Beryllium
Cf-252
-
Carlifornium-252
Gd
-
Gadolinium
MCNP
-
Monte Carlo N-Particle
FIR
-
Flux image radiograph
PScF
-
Point scattered function
l(x)
-
Line spread function (LSF)
e(x)
-
Edge spread function (ESF)
h(x,y)
-
Point spread function (PSF)
M(u)
-
Modulation Transfer Function (MTF)
f(x)
-
Input function
F(u)
-
Fourier Transform
xv
σ
-
Standard deviation
δ(x)
-
Delta function
ROI
-
Region of Interest
FWHM
-
Full Width at Half Maximum
xvi
LIST OF APPENDICES
APPENDIX
TITLE
PAGE
A
Publications
65
B
Material safety data sheet for cadmium
66
C
Codes for MCNP simulation for 1 mm thick of
cadmium without scattering material
D
69
Codes for MCNP simulation for 1 mm thick of
cadmium with scattering material
70