design on target and moderator of x- band compact electron linac neutron source for short pulsed...
TRANSCRIPT
Design on Target and Moderator of X-band Compact Electron Linac Neutron Source for Short Pulsed Neutrons
Design on Target and Moderator of X-band Compact Electron Linac Neutron Source for Short Pulsed Neutrons
Kazuhiro Tagi
2
Self IntroductionSelf Introduction Name: Kazuhiro Tagi
Born near Kyoto 2008-2012 Graduate School of Engineering in UT
Environmental & Energy Problem Global warming, Energy Resource (including nuclear
energy) Graduation Thesis: X-ray gas detector for radiation
therapy 2012-2014 Master Course in UT 2014- Ph D student in UT
Nuclear EngineeringOctober 16th, 2013
3
Uesaka Lab in the Univ of TokyoUesaka Lab in the Univ of Tokyo Development of X-band Linac Facility for
Medical and Industrial Application
October 16th, 2013
4
Pinpoint X-ray Therapy with 6 MeV X-band LinacPinpoint X-ray Therapy with 6 MeV X-band Linac
October 16th, 2013
Robot
Flat-panel detector
X-ray Source
Treatment table robot
Accelerator
X-ray detector(Developed in this research)
CCD camera
5
Uesaka Lab in the Univ of TokyoUesaka Lab in the Univ of Tokyo
System development for radiation therapy
Laser driven dielectric accelerator for radiation biology
Radiation biology
October 16th, 2013
6
Compact Neutron Source by X-band LinacCompact Neutron Source by X-band Linac
Facility where nuclear fuels can be measured is limited.
Univ. of Tokyo has a reactor ‘Yayoi,’ which is now under decommissioning, and by installing accelerator in it, it becomes possible to measure nuclear fuel materials.
Space in the reactor is limited, so accelerator should be smaller
Accelerator tube of X-band is 1/4 smaller than that if S-band,
Beam current is also less than 1/2 If TOF beam line is long, measurement time is also
long, so short pulse is necessary for short TOF beam line length.October 16th,
2013
X-band Linac Neutron Source
7
Demand for Accuracy of Nuclear Cross SectionDemand for Accuracy of Nuclear Cross Section
Analysis of debris in Fukushima 1st nuclear power plant
Waste treatment with ADSDebris measurement with NRD [1] Spectra of fuel samples [2]
[1] H. Tsuchiya, et. al., Nucl. Inst. and Meth. A 729 (2013) 338 [2] Behrens et al., Nucl. Techn. 67 (1984) 162
8
PurposePurpose
Now I’m designing Electron incident system Target & Moderator
To develop neutron cross section measurement system with X-band linac neutron source in order to analyze debris in Fukushima 1st nuclear plant and nuclear waste treatment with ADS
October 16th, 2013
Short pulsed neutron is required. X-band has small beam current Short TOF length (Our plan is 5 m)
is required for making measuring time shorter.
9
Compton Scattering X-ray SourceCompton Scattering X-ray Source
October 16th, 2013
RF source ( 50 MW )
Electron Source multi bunch Electron Beam Generation ( 3 MeV )
Accelerator tube (About 30 MeV)
Beam dump
LaserLong Pulse ( 10 nsec )
Transportation systemFocus magnet + Measurement, Control, vacuum, cooling system
The Linac was originally designed for Compton scattering monochromatic X-ray source.
10
Component of X-band Linac Neutron SourceComponent of X-band Linac Neutron Source
October 16th, 2013
Pulse width of electron beam 10 ns – 1 us is possible in our system Moderator Detector Ce:LiCaF Detector is being developed
11
Design of Incident SystemDesign of Incident System 20 keV Thermal Gun + 5 MeV Buncher
Electron beam will be bunched in buncher Efficiency of 25% can be expected.
100 keV Thermal gun directly connected to the accelerator
In 100 keV, Efficiency of 25% can be expected Easy to make and cheaper Broad Energy spectrum
October 16th, 2013
12
Optimization of Moderator for 100 keV NeutronOptimization of Moderator for 100 keV Neutron
Motivation In Japan, there is no facility which measures -100 keV cross
sections of nuclear fuel materials. Accuracy of capture cross section in keV region should be
improved.
Calculation Condition Neutron Target
Photo nuclear reaction, Material is tungsten Moderator material is Polyethylene. Angle between electron beam and neutron beam is 90° Relative intensity and Pulse width was calculated with
many moderator geometry. PHITS, one of Monte Carlo simulation code, was used for
simulation.October 16th, 2013
13
Results of optimization of Polyethylene ModeratorResults of optimization of Polyethylene Moderator
October 16th, 2013
Electron Energy Power Pulse Width(10 – 100 keV)
30 MeV 0.4 kW 5.8 ns
Energy Spectrum of NeutronsNeutronIntensity
Neutron FluxAt 5 m TOF line
1.3×1011n/s 1.7×103 n/cm2/s
14
Moderator Made of Hydrogen Storage MaterialModerator Made of Hydrogen Storage Material
October 16th, 2014
Moderator (??)5 cm × 5 cm
Neutron beam
Tungsten TargetΦ= 1 cm
5 cm
Polyethylene
BeH2 TiH2 Mg(BH4)2
Density of Hydrogen
0.136 g/cm3 0.118 g/cm3
0.151 g/cm3
0.219 g/cm3
10-100 keV Pulse Width
5.6 ns 5.8 ns 4.8 ns 4.4 ns
10-100 keV Flux
4.2 4.1 3.7 4.3
Thermal Pulse Width
47 us 41 us 14 us 0.146 us
Thermal Flux 5.5 4.0 3.1 0.01• If density of hydrogen is bigger, pulse width is
shorter• Boron absorbs thermal neutrons in Mg(BH4)2, so
hard spectrum can be gained
15
ConclusionConclusion
In the University of Tokyo, compact electron linac driven neutron source is being developed.
Focusing on high energy (〜 100 keV) neutrons, neutron target and moderator were simulated in order to optimize for short pulse neutron
From the simulation result, pulse width of 10 – 100 keV neutrons were broadened to 5.8 ns.
Novel materials, such as hydrogen absorbing alloy, has been simulated, and showed excellent properties for short pulse moderator.
Neutron detector is also being developed[4], and neutron beam will be measured.
October 16th, 2013