PHITSEvaluation of Induced Radioactivity:
Connection between PHITS & DCHAIN-SP
Multi-Purpose Particle and Heavy Ion Transport code System
Title 1
Last update 2015/06
Purpose 2
PHITS can calculate the induced radioactivity just after pulse irradiation, but cannot estimate their time variation
DCHAIN-SP can calculate the time variation of induced radioactivity as well as heat and gamma-ray spectrum due to the radioactive decays
In this lecture, you will learn how to connect PHITS and DCHAIN-SP, and calculate the time variation of the induced radioactivity using these 2 codes.
Purpose
Glossary 3
TerminologyRadioactivity :
Radiative Isotope:
(Ionizing) Radiation:
• Activity of matter to emit radiations due to decay of unstable isotopes (Unit = Bq)
• Unstable isotopes that can decay and emit radiations
• Particles (neutron, proton photon etc.) that travels through some matter by ionizing it
• PHITS can handle the transport of only radiation
Both radiation dose and radioactivity must be evaluated in the shielding design of nuclear facilities
Table of Contents
4
1. Abstract
2. Parameter settings in [t-dchain]
3. Output files from DCHAIN-SP
4. Exercises
5. Summary
Table of Contents
Overview 5
Flowchart of Connection CalculationPHITS
Particle Transport Simulation
Basic input file for DCHAIN-SP (specified by “file=“)
Nuclear yield calculated by [t-yield] ( *.dyld, nmtc_yield )
Neutron fluxes below 20 MeV calculated by [t-track] ( *.dtrk, n.flux_**)
Information on the path of data library used in DCHAIN-SP (dch_link.dat)
Output files from [t-dchain]
DCHAIN-SP
Decay chain calculation
Data libraries for DCHAIN-SP Activation cross section for neutron
(1968 groups) γ-ray spectrum and decay chain Electron capture & ratio of β+ decay
Calculation Results Induced activity ( Bq) Decay heat ( W ) Emitted γ-ray spectrum
during and after irradiation
6
Let’s Try! Execute PHITS with “dchain.inp” (send to ->
PHITS)(150pH2O.out, .dtrk, .dyld, dch_link.dat, n.flux_**, nmtc_yield are generated)
( 150pH2O.lst, .act, .pht, .ang, .gsd, .gso, .alr, .eps are generated )
Time variation of induced activity in each cell
150pH2O.eps
Overview
Execute DCHAIN-SP with “150pH2O.out” (send to -> DCHAIN)
7
Output files from [t-dchain] 150pH2O.out: Basic input file for DCHAIN-SP ( File name is specified by “file=“ in [t-dchain])
150pH2O.dyld: Nuclear yields calculated by [t-yield]
nmtc_yield: Nuclear yields written in DCHAIN-SP input format
150pH2O.dtrk: Neutron fluxes below 20 MeV calculated by [t-track]*
n.flux_**: Neutron fluxes below 20 MeV written in DCHAIN-SP format
dch_link.dat: Folder name containing the libraries for DCHAIN-SP (specified by “file(21)=“ in [parameters] )
*In principle, time variation of induced activity can be calculated only from the nuclear yields calculated by [t-yield]. However, the calculation accuracy can be improved when nuclear yields from neutrons below 20 MeV are separately calculated in DCHAIN-SP using specially developed activation cross sections
Overview
20MeV
total t-track t-yield0MeV( ) ( )dY E E E Y
8
Output files from DCHAIN-SP 150pH2O. lst : Basic output file (similar to
“phits.out” in PHITS)
150pH2O.act: Main output (Induced radioactivity, decay heat,
150pH2O.pht: γ-ray spectrum written in PHITS input format
150pH2O.ang: Induced radioactivity, decay heat, dose rates
150pH2O.eps: Graphs generated by ANGEL using above file
150pH2O.gsd: γ-ray spectrum written in MCNP input format
150pH2O.yld: Nuclear yields when irradiation and cooling is finished
150pH2O.gso: Origin nuclei and their contribution for emitting γ-ray
150pH2O.alr: Induced radioactivity and decay heat
Overview
dose rate, emitted γ-ray spectrum)
written in ANGEL input format
9
Some parameters used in DCHAIN-SP can be also specified in [t-dchain] section
In general, their default values are adequately set, and need not to be changed. If you would like to change them, please read the manual of DCHAIN-SP for their meanings*/phits/dchain-sp/manual/DCHAIN-SP2014-jpn.pdf
Overview
Important Notice
Only one [t-dchain] is allowed in an PHITS input file
“Mesh” should be “reg” and combined cells cannot be specified in [t-dchain]
Limitation of Current Version
Table of Contents
10
1. 使用方法の概要
2. [t-dchain] のパラメータ設定
3. DCHAIN-SP の出力ファイル
4. 演習
5. まとめ
実習内容
Parameter Setting 11
Check Calculation Result
150 MeV Proton
Water
Vacuum
Irradiate 150 MeV protons into 3 cylindrical water tanks (10 radius x 10 cm height each)
yz-track.eps
12
Settings for using [T-Dchain]dchain.inp
[ P a r a m e t e r s ]...$ must option for DCHAIN jmout = 1 # (D=0) Density echo, 0:input, 1:number densityfile(21) = c:/phits/dchain-sp/data # dchain data folder name e-mode = 0 # (D=0) Event generator mode…[ V o l u m e ] $ must section for DCHAIN reg vol 1 pi*c1*c2**2 $ c1&c2: height and radius of cylinder (cm) 2 pi*c1*c2**2 $ c1&c2: height and radius of cylinder (cm) 3 pi*c1*c2**2 $ c1&c2: height and radius of cylinder (cm)
[volume] section & jmout must be set because DCHAIN-SP is necessary to know the number of nuclei in each cell
Event Generator Mode should not be used ( e-mode = 0) because nuclear yields from low-energy neutron interactions are separated calculated in DCHAIN-SP
Folder name for DCHAIN-SP libraries must be specified by file(21)
Parameter Setting
13
Example of [T-Dchain]dchain.inp [ T - D C H A I N ]
$ must section for DCHAIN title = 150MeV proton into water mesh = reg reg = 1 2 3 file = 150pH2O.out timeevo = 2 6.0 m 1.0 50.0 m 0.0 outtime = 7 1.0 m 3.0 m 6.0 m 10.0 m 20.0 m 30.0 m 40.0 m$ beam current (nA)set:c21[100.0]amp = c21*1.0e-9/1.602e-19 # (D=1.0) Source Intensity
Basic parameters ・ file (input file name for DCHAIN-SP) ・ mesh (must be “reg” ) ・ amp 、 timeevo (Irradiation condition ) ・ outtime (Output timing)
Parameter Setting
file : Input file name for DCHAIN-SP ・ Following file names are not allowed because
PHITS or DCHAIN-SP automatically generate them
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Parameters in [T-Dchain][ T - D C H A I N ] $ must section for DCHAIN title = 150MeV proton mesh = reg reg = 1 2 3 file = 150pH2O.out timeevo = 2 6.0 m 1.0 50.0 m 0.0 outtime = 7 1.0 m 3.0 m 6.0 m 10.0 m 20.0 m 30.0 m 40.0 m$ beam current (nA)set:c21[100.0]amp = c21*1.0e-9/1.602e-19
***.dtrk, ***.dyld, ***_err.dyld, ***.dout, ***.lst, ***.yld, ***.gsd, ***.gso, ***.alr, ***.act, ***.ang, ***.pht, n.flux_01 ~ n.flux_99, nmtc_yield, dch_link.dat
Parameter Setting
mesh : should be “reg” at this moment reg = specify cell ID
Combined cell, e.g. (1 2), cannot be used amp : Beam amplitude (source/sec) timeevo : Number of irradiation and
cooling time steps. After this line, time and relative amplitude must be specified
15
[ T - D C H A I N ] $ must section for DCHAIN title = 150MeV proton mesh = reg reg = 1 2 3 file = 150pH2O.out timeevo = 2 6.0 m 1.0 50.0 m 0.0 outtime = 7 1.0 m 3.0 m 6.0 m 10.0 m 20.0 m 30.0 m 40.0 m$ beam current (nA)set:c21[100.0]amp = c21*1.0e-9/1.602e-19
Example:6.0 m 1.0 → irradiate 6 minutes by full amplitude50.0 m 0.0 → cool 50 minutes
Parameter Setting
Parameters in [T-Dchain]
• s (second), m (minute), h (hour), d (day), y (year)
• You have to insert space before and after them
outtime : Number of output timing
16
Parameters in [T-Dchain][ T - D C H A I N ] $ must section for DCHAIN title = 150MeV proton mesh = reg reg = 1 2 3 file = 150pH2O.out timeevo = 2 6.0 m 1.0 50.0 m 0.0 outtime = 7 1.0 m 3.0 m 6.0 m 10.0 m 20.0 m 30.0 m 40.0 m$ beam current (nA)set:c21[100.0]amp = c21*1.0e-9/1.602e-19
After this line, output timing must be specified in the same manner as timeevo Positive value: Count from the
beginning of the first irradiation Negative value: Count from the
end of the last irradiation
You cannot specify time after the last time specified by timeevo; 56 m in this case
Parameter Setting
17
Relation between timeevo & outtime
dchain.inp [ T – D c h a i n ] timeevo = 2 6.0 m 1.0 50.0 m 0.0 outtime = 7 1.0 m 3.0 m 6.0 m 10.0 m 20.0 m 30.0 m 40.0 m
Irradiation time and output timing
( min )
Irradiation timeIrradiation for 6.0 m
Cooling for 50 m
← specified by timeevo
Output timing ← specified by outtime
Cannot
specify
Parameter Setting
18
[ T – D c h a i n ] mesh = reg reg = 100 file = testDC.spd title = [t-dchain] test calc. amp = 1.0E12
timeevo = 4 3.0 h 1.0 2.0 h 0.0 3.5 h 1.0 15.5 h 0.0
outtime = 3 3.0 h -1.0 h -3.0 h
時間
Irradiation Irradiation
Cooling Cooling
End of the last irradiation step3.0
h 2.0 h
3.5 h 15.5 h
3.0 h
1.0 h 3.0
h
Manual
Parameter Setting
Relation between timeevo & outtime
Irradiation time
← specified by timeevo
Irradiation time and output timing
- in the case of using negative outtime -
Output timing ← specified by outtime
Table of Contents
19
1. 使用方法の概要
2. [t-dchain] のパラメータ設定
3. DCHAIN-SP の出力ファイル
4. 演習
5. まとめ
実習内容
20
Basic Output File (*.lst)
*** error message from s.rdinpt *** total flux of neutron irradiation was less than 0. no. of region= 1 jmode= 2 fluxs= 0.0000E+00
*** error message from main *** primary file is not found. file name = /spd-dcylib
↑ Neutron flux is 0 in some cells
↑ Library file is found
DCHAIN-SP Output
150pH2O.lst : Similar to “phits.out” in PHITS
Errors messages might be given at the end of the file
Solution1: Restart PHITS calculation to obtain better statistics Solution2-1: Set “jmode = 0” (if neutron fluxes for all cells are 0) Solution2-2: Delete the cell information (if neutron fluxes only for
some cells are 0)
Solution1: Correct “file(21)” in [parameters] section & Execute PHITS again
Solution2: Correct “dch_link.dat” by yourself -> easier
150pH2O.act: Induced activity, decay heat & dose rates
21
Main Output File (*.act)
Calculated results are given for each cell and output timing
← Output timing
Induced Activity (Bq)
Dose rate
(uSv/h*m2)Decay Heat
(W)
← Cell
Many output files are generated from DCHAIN-SP (see its manual in more detail)
DCHAIN-SP Output
22
Graphic Output File (*.eps)
150pH2O.eps Time variation for each cell (dot+line) & total (thick line)
Induced activity Decay heat β decay heat*
γ decay heat* α decay heat* Dose rate**
**Ambient dose equivalent H*(10) rate at 1 m away from the point source
*Decay heat due to β-ray, γ-ray, and α-ray emissions, respectively
DCHAIN-SP Output
Table of Contents
23
1. 使用方法の概要
2. [t-dchain] のパラメータ設定
3. DCHAIN-SP の出力ファイル
4. 演習
5. まとめ
実習内容
24
Check current input & output
Induced activity becomes the maximum at 6 minutes (360 seconds)
[ T - D C H A I N ] $ must section for DCHAIN title = 150MeV proton mesh = reg reg = 1 2 3 file = 150pH2O.out timeevo = 2 6.0 m 1.0 50.0 m 0.0outtime = 7 1.0 m 3.0 m 6.0 m 10.0 m 20.0 m 30.0 m 40.0 m$ beam current (nA)set:c21[100.0]amp = c21*1.0e-9/1.602e-19
150pH2O.eps
Activity becomes smaller with increase of depth ( cell 1 > cell 2 > cell 3 )
Exercise
dchain.inp
Exercise 25
Exercise 1Change irradiation time
[ T - D C H A I N ] $ must section for DCHAIN title = 150MeV proton mesh = reg reg = 1 2 3 file = 150pH2O.out timeevo = 2 6.0 m 1.0 50.0 m 0.0 outtime = 7 1.0 m 3.0 m 6.0 m 10.0 m 20.0 m 30.0 m 40.0 m$ beam current (nA)set:c21[100.0]amp = c21*1.0e-9/1.602e-19
Before 6.0 m 1.0 → irradiate 6 minutes by full
amplitude 50.0 m 0.0 → cool 50 minutesAfter Irradiate 5 minutes by full
amplitude Cool 5 minutes Irradiate 5 minutes by a half
amplitude Cool 1 hour
→ Execute PHITS & DCHAIN
dchain.inp
timeevo : Number of irradiation and cooling time steps. After this line, time and relative amplitude must be specified• s (second), m (minute), h (hour), d (day), y
(year)• You have to insert space before and after them
26
Exercise 1 (Answer)
Induced activity becomes larger at 20 minute (1200 seconds) after the first irradiation
[ T - D C H A I N ] $ must section for DCHAIN title = 150MeV proton mesh = reg reg = 1 2 3 file = 150pH2O.out timeevo = 4 5.0 m 1.0 5.0 m 0.0 10.0 m 0.5 1.0 h 0.0outtime = 7 1.0 m 3.0 m 6.0 m 10.0 m 20.0 m 30.0 m 40.0 m$ beam current (nA)set:c21[100.0]amp = c21*1.0e-9/1.602e-19
150pH2O.eps
Exercise
dchain.inp
27
Exercise 2Change output timing
(after 30th line)! --- irradiation time --- itstep = 4 5.0000E+00 m 1.0000E+00 5.0000E+00 m 0.0000E+00 1.0000E+01 m 5.0000E-01 1.0000E+00 h 0.0000E+00
! --- output time --- itout = 7 1.0000E+00 m 3.0000E+00 m 6.0000E+00 m 1.0000E+01 m 2.0000E+01 m 3.0000E+01 m 4.0000E+01 m
Before1, 3, 6, 10, 20, 30, and 40 minutes after the first irradiation
After1, 3, 5, 7, 10, 13, 16, 20, 25, 30, and 40 minutes after the first irradiation (11 points)
itout: Number of output timings
150pH2O.out
corresponding to “outtime” in [t-dchain]
→ Change “150pH2O.out” and execute only DCHAIN-SP
( You can reduce the number if you use a slow computer )
Exercise
28
Exercise 2 (Answer)
You do not have to execute PHITS again if you would like to change only the irradiation time and output timing
(after 30th lines)! --- irradiation time --- itstep = 4 5.0000E+00 m 1.0000E+00 5.0000E+00 m 0.0000E+00 1.0000E+01 m 5.0000E-01 1.0000E+00 h 0.0000E+00
! --- output time --- itout = 11 1.0000E+00 m 3.0000E+00 m 5.0000E+00 m 7.0000E+00 m 1.0000E+01 m 1.3000E+01 m 1.6000E+01 m 2.0000E+01 m 2.5000E+01 m 3.0000E+01 m 4.0000E+01 m
150pH2O.out
Exercise
150pH2O.pht : γ-ray spectrum written in the PHITS input format
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Use γ-ray spectrum as [source]
← Each cell← Each output timing
Region for source generation
150pH2O.pht
You have to define a rectangle that covers the whole cell for generating source because DCHAIN does not know the source location and shape Isotropic source (dir=all)
Energy distribution is expressed in successive type (e-type=4) Exercise
← rectangular source shape (s-type=5)
30
Exercise 3Execute PHITS again using γ-ray spectrum calculated by DCHAIN-SP
[ S o u r c e ] off s-type = 1 …
[ S o u r c e ] s-type = 5 proj = photon reg = 1 x0 = x1 = y0 = y1 = z0 = z1 = dir = all e-type = 4 ne = 37 0.0010 3.8688E+04 0.0100 0.0000E+00 0.0200 0.0000E+00…
1.Insert “off” after current [source] section
2.Copy the 1st [source] section in “150pH2O.pht” and paste to “dchain.inp” ( cell 1, output timing = 1 m)
3.Input appropriate rectangle size for source generation
dchain.inp
→ change “dchain.inp” and execute PHITS
Cell 1 is covered by -10 cm < x < 10 cm -10 cm < y < 10 cm 0 cm < z < 10 cm
Not necessary to be the exact size, but too big size is not recommended
Exercise
31
Exercise 3 (Answer)
[ S o u r c e ] off s-type = 1 …
[ S o u r c e ] s-type = 5 proj = photon reg = 1 x0 = -10.0 x1 = 10.0 y0 = -10.0 y1 = 10.0 z0 = 0.0 z1 = 10.0 dir = all e-type = 4 ne = 37 0.0010 3.8688E+04 0.0100 0.0000E+00 0.0200 0.0000E+00…
dchain.inp
Photons are generated from the whole region of cell 1
yz-track.eps , page 3
Exercise
Table of Contents
32
1. 使用方法の概要
2. [t-dchain] のパラメータ設定
3. DCHAIN-SP の出力ファイル
4. 演習
5. まとめ
実習内容
DCHAIN-SP can calculate the time variation of induced activity, decay heat, γ-ray spectrum, and dose rates during irradiation and cooling time
PHITS automatically generate an input file of DCHAIN-SP by using [t-dchain] tally
Combination of PHITS & DCHAIN-SP enables to estimate the long-term variation of induced activity whose information is necessary for the design of nuclear and accelerator facilities
Summary 33
Summary
34
Allow multiple [T-Dchain] in a PHITS input file
Improve the function for using γ-ray spectrum calculated by DCHAIN-SP as [source] in PHITS
e.g.) automatic normalization, use discrete spectrum
Allow xyz-mesh in [t-dchain] section
Directly implement DCHAIN-SP into PHITS
Summary
Future Plans