Title Page
ABSTRACT
국문 초록
PREFACE
Contents
CHAPTER 1. INTRODUCTION 16
1.1. Use of Cyclotrons 16
1.2. Generation of Radioactive Materials 19
1.3. Management and Plan 21
1.4. Evaluation Methods of Activation 23
CHAPTER 2. CHARACTERISTICS OF NEUTRON 24
2.1. Neutron Sources Production 24
2.1.1. Neutron Generation by using Radioisotope 24
2.1.2. Neutron Generation by using Accelerator 26
2.1.3. Neutron Generation by using Nuclear Reactor 27
2.2. Properties and Classification of Neutrons 28
2.3. Interaction of Neutrons with Matter 31
2.3.1. Elastic Scattering 31
2.3.2. Inelastic Scattering 32
2.3.3. Neutron Capture 33
2.3.4. Nuclear Fission 34
2.4. Neutron Cross Section 35
CHAPTER 3. MATERIALS AND METHODS 37
3.1. Materials 37
3.2. Irradiation Experimental Setup 39
3.3. Activation Measurement 41
3.4. Activation Calculation 45
CHAPTER 4. RESULTS AND DISCUSSION 47
4.1. Case 1 47
4.2. Case 2 56
CHAPTER 5. CONCLUSION 65
REFERENCES 67
Table 1. Radionuclides commonly identified in solid materials irradiated around accelerators. 20
Table 2. Classification of free neutrons according to kinetic energies 28
Table 3. Major parameters of the cyclotron 37
Table 4. FISPACT-II input material nuclear data 46
Table 5. Characteristics of radionuclides generated from each substance in the Case 1 experiment and the main nuclear reaction formula. 49
Table 6. Comparison of FISPACT-II and measurement activity values in the substances of the Case 1 experiment. Red values indicate exceeding the clearance level. 53
Table 7. Comparison of FISPACT-II and measurement relative activity values according to the depth of concrete in the Case 2 experiment. 64
Figure 1. Number of cyclotrons worldwide from 2009 to 2016 17
Figure 2. Schematic diagram of two methods of generating RI using an accelerator. (a) ISOL, (B) IF 18
Figure 3. Conceptual illustration of the waste classification scheme. 22
Figure 4. Typical construction of neutron source (α, n) in a sealed container. 25
Figure 5. Energy distribution of fission neutrons. The most probable energy is 0.7 MeV and the average energy is 2 MeV. 27
Figure 6. Maxwell-Boltzmann distribution of energy among gas molecules. 30
Figure 7. Schematic of the 70-MeV proton beam dump target. The proton beam incident inthe target passes through the beam window and is dumped in to the water. 38
Figure 8. A layout of the cyclotron floor 39
Figure 9. Irradiation experiment setup layout. (a) Plan of irradiation area, (b) Vertical outline 40
Figure 10. The gamma spectrometer 41
Figure 11. CRM (KRISS) used for gamma spectrometer energy calibration and efficiency measurement. (a) was used for measuring a 47-mm diameter paper filter, which... 43
Figure 12. Neutron spectrum in Case 1 samples direction to the proton beam indicated as position in Fig. 9. 48
Figure 13. Gamma spectroscopy of Case 1 samples after a cooling time of 7 days using HPGe gamma spectrometer. (a) Aluminum, (b) Concrete, (c) Stainless steel 51
Figure 14. Relative activity values (∑iCl/CLi) calculated from FISPACT-II and measurement data shown according to the decay time. The red line is the clearance criterion....[이미지참조] 55
Figure 15. (a) Neutron spectrum for depth in the Case 2 samples direction to the proton beam indicated as position in Fig. 2. (b) Neutron flux (10¯⁴ eV ≤ E ≤ 1 eV) by depth 57
Figure 16. Radioactivity values for each nuclide in the Case 2 samples as a function of depth. The rest nuclides except for ²⁴Na indicated upon applying 10 times the... 60
Figure 17. ENDF/B-VIII.0 (February 2, 2018) radiative capture cross-section (n, r) [21]. (a) ⁵⁸Fe (n, r) ⁵⁹Fe, (b) ⁵⁹Co (n, r) ⁶⁰Co 61
Figure 18. Radioactivity values of ⁵⁹Fe and ⁶⁰Co as a function of concrete depth calculated by increasing the hydrogen ratio of concrete in computational simulation. 63