1. Multi-Purpose Particle and Heavy Ion Transport code System
PHITS
Multi-Purpose Particle and Heavy Ion Transport code System
Evaluation of Induced Radioactivity:
Connection between PHITS & DCHAIN-SP
PHITS講習会　入門実習
May 2016 revised
Title 1

2. Purpose
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 2

3. Terminology Radioactivity： Radioactive 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
Glossary 3

4. Table of Contents Abstract Parameter settings in [t-dchain]
Output files from DCHAIN-SP
Exercises
Summary
PHITS講習会　入門実習
Table of Contents 4

5. Flowchart of Connection Calculation
PHITS
DCHAIN-SP
Particle Transport Simulation
Calculation Results
Induced activity（Bq)
Decay heat （W）
Emitted γ-ray spectrum
Output files from [t-dchain]
during and after irradiation
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)
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
Overview 5

6. Let’s Try! Execute PHITS with “dchain.inp” (send to -> PHITS)
(tdchain.out, .dtrk, .dyld, dch_link.dat,
n.flux_**, nmtc_yield are generated)
Execute DCHAIN-SP with “tdchain.out” (send to -> DCHAIN)
（tdchain.lst, .act, .pht, .ang, .gsd, .gso, .alr, .eps are generated）
tdchain.eps
Time variation of induced activity in each cell
Overview 6

7. Output files from [t-dchain]
tdchain.out: Basic input file for DCHAIN-SP
　　　　　　　　　　（File name is specified by “file=“ in [t-dchain])
tdchain.dyld: Nuclear yields calculated by [t-yield]
nmtc_yield: Nuclear yields written in DCHAIN-SP input format
tdchain.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 7

8. Output files from DCHAIN-SP
tdchain.ｌｓｔ: Basic output file (similar to “phits.out” in PHITS)
tdchain.act: Main output (Induced radioactivity, decay heat,
tdchain.pht: γ-ray spectrum written in PHITS input format
tdchain.ang: Induced radioactivity, decay heat, dose rates
tdchain.eps: Graphs generated by ANGEL using above file
tdchain.gsd: γ-ray spectrum written in MCNP input format
tdchain.yld: Nuclear yields when irradiation and cooling is finished
tdchain.gso: Origin nuclei and their contribution for emitting γ-ray
tdchain.alr: Induced radioactivity and decay heat
dose rate, emitted γ-ray spectrum)
written in ANGEL input format
Overview 8

9. Important Notice
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
Limitation of Current Version
Only one [t-dchain] is allowed in an PHITS input file
“Mesh” should be “reg” and combined cells cannot be specified in [t-dchain]
Overview 9

10. Table of Contents Abstract Parameter settings in [t-dchain]
Output files from DCHAIN-SP
Exercises
Summary
PHITS講習会　入門実習
Table of Contents 10

11. Check Calculation Result
yz-track.eps
150 MeV Proton
Water
Vacuum
Irradiate 150 MeV protons into 3 cylindrical water tanks (10 radius x 10 cm height each) 　
Parameter Setting 11

12. Settings for using [T-Dchain]
dchain.inp
[ P a r a m e t e r s ]
...
$ must option for DCHAIN
jmout = # (D=0) Density echo, 0:input, 1:number density
e-mode = # (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
Parameter Setting 12

13. Example of [T-Dchain] dchain.inp Basic parameters
$ must section for DCHAIN
title = 150MeV proton into water
mesh = reg
reg =
file = tdchain.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 13

14. Parameters in [T-Dchain]
$ must section for DCHAIN
title = 150MeV proton
mesh = reg
reg =
file = tdchain.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
file：Input file name for DCHAIN-SP
　・ Following file names are not allowed because
PHITS or DCHAIN-SP automatically generate them
***.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 14

15. Parameters in [T-Dchain]
$ must section for DCHAIN
title = 150MeV proton
mesh = reg
reg =
file = tdchain.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
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
Example:
6.0 m 1.0 → irradiate 6 minutes by full amplitude
50.0 m 0.0 →　cool 50 minutes
s (second), m (minute), h (hour), d (day), y (year)
You have to insert space before and after them
Parameter Setting 15

16. Parameters in [T-Dchain]
$ must section for DCHAIN
title = 150MeV proton
mesh = reg
reg =
file = tdchain.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
outtime：Number of output timing　　
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 16

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
← specified by timeevo
Irradiation for 6.0 m
Cooling for 50 m
（min）
Output timing
← specified by outtime
Cannot specify
Irradiation time and output timing
Parameter Setting 17

18. Relation between timeevo & outtime
- in the case of using negative outtime -
Manual
[ 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
Irradiation time
← specified by timeevo
Irradiation Irradiation
End of the last irradiation step
3.0 h
3.5 h
2.0 h
15.5 h
Cooling Cooling 時間
3.0 h
1.0 h
3.0 h
Output timing
← specified by outtime
Irradiation time and output timing
Parameter Setting 18

19. Table of Contents Abstract Parameter settings in [t-dchain]
Output files from DCHAIN-SP
Exercises
Summary
PHITS講習会　入門実習
Table of Contents 19

20. Basic Output File (*.lst)
tdchain.lst： Similar to “phits.out” in PHITS
Errors messages might be given at the end of the file
*** error message from main ***
primary file is not found.
file name = /spd-dcylib
↑ Library file is found
Solution1: Correct “file(21)” in [parameters] section & Execute PHITS again
Solution2: Correct “dch_link.dat” by yourself -> easier
*** error message from s.rdinpt ***
total flux of neutron irradiation was less than 0.
no. of region= 1 jmode= 2 fluxs= E+00
↑ Neutron flux is 0 in some cells
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)
DCHAIN-SP Output 20

21. Main Output File (*.act)
tdchain.act: Induced activity, decay heat & dose rates
Calculated results are given for each cell and output timing
← Cell
← Output timing
Dose rate
(uSv/h*m2)
Decay Heat (W)
Induced Activity (Bq)
Many output files are generated from DCHAIN-SP (see its manual in more detail)
DCHAIN-SP Output 21

22. Graphic Output File (*.eps)
Induced activity
Decay heat
β decay heat*
γ decay heat*
α decay heat*
Dose rate**
tdchain.eps
Time variation for each cell (dot+line) & total (thick line)
*Decay heat due to β-ray, γ-ray, and α-ray emissions, respectively
**Ambient dose equivalent H*(10) rate at 1 m away from the point source
DCHAIN-SP Output 22

23. Table of Contents Abstract Parameter settings in [t-dchain]
Output files from DCHAIN-SP
Exercises
Summary
PHITS講習会　入門実習
Table of Contents 23

24. Check current input & output
dchain.inp
[ T - D C H A I N ]
$ must section for DCHAIN
title = 150MeV proton
mesh = reg
reg =
file = tdchain.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
tdchain.eps
Induced activity becomes the maximum at 6 minutes (360 seconds)
Activity becomes smaller with increase of depth
　　（cell 1＞cell 2＞cell 3）
Exercise 24

25. Exercise 1 Change irradiation time dchain.inp Before After
[ T - D C H A I N ]
$ must section for DCHAIN
title = 150MeV proton
mesh = reg
reg =
file = tdchain.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 minutes
After
Irradiate 5 minutes by full amplitude
Cool 5 minutes
Irradiate 10 minutes by a half amplitude
Cool 1 hour
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
→　Execute PHITS & DCHAIN
Exercise 25

26. Exercise １(Answer) dchain.inp tdchain.eps
$ must section for DCHAIN
title = 150MeV proton
mesh = reg
reg =
file = tdchain.out
timeevo = 4
5.0 m 1.0
5.0 m 0.0
10.0 m 0.5
1.0 h 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
tdchain.eps
Induced activity becomes larger at 20 minute (1200 seconds) after the first irradiation
Exercise 26

27. Exercise 2 Change output timing tdchain.out Before After
(after 30th line)
! --- irradiation time ---
itstep =
5.0000E+00 m E+00
5.0000E+00 m E+00
1.0000E+01 m E-01
1.0000E+00 h E+00
! --- output time ---
itout =
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
Before
1, 3, 6, 10, 20, 30, and 40 minutes after the first irradiation
After
1, 3, 5, 7, 10, 13, 16, 20, 25, 30, and 40 minutes after the first irradiation (11 points)
（You can reduce the number if you use a slow computer）
itout: Number of output timings
corresponding to “outtime” in [t-dchain]
→Change “tdchain.out” and execute only DCHAIN-SP
Exercise 27

28. Exercise 2 (Answer) tdchain.out
(after 30th lines)
! --- irradiation time ---
itstep =
5.0000E+00 m E+00
5.0000E+00 m E+00
1.0000E+01 m E-01
1.0000E+00 h E+00
! --- output time ---
itout =
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
You do not have to execute PHITS again if you would like to change only the irradiation time and output timing
Exercise 28

29. Use γ-ray spectrum as [source]
tdchain.pht： γ-ray spectrum written in the PHITS input format
tdchain.pht
← Each cell
← Each output timing
Normalization factor (/sec)
←rectangular source shape (s-type=5)
Region for source generation
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 29

30. Exercise 3
dchain.inp
Execute 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 ]
totfact = E+10
s-type = 5
proj = photon
reg =
x0 =
x1 =
y0 =
y1 =
z0 =
z1 =
dir = all
e-type = 4
ne =
$ Energy Flux
$ ^^^^ Energy
E+04
E+00
E+00
Insert “off” after current [source] section
Copy the 1st [source] section in “tdchain.pht” and paste to “dchain.inp” （cell 1, output timing = 1 m)
Input appropriate rectangle size for source generation
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
→ change “dchain.inp” and execute PHITS
Exercise 30

31. Exercise 3 (Answer) dchain.inp yz-track.eps，page 3
[ S o u r c e ] off
s-type = 1 …
[ S o u r c e ]
totfact = E+10
s-type = 5
proj = photon
reg =
x0 =
x1 =
y0 =
y1 =
z0 = 　0.0　
z1 =
dir = all
e-type = 4
ne =
$ Energy Flux
$ ^^^^ Energy
E+04
E+00
E+00
yz-track.eps，page 3
Photons are generated from the whole region of cell 1
Exercise 31

32. Table of Contents Abstract Parameter settings in [t-dchain]
Output files from DCHAIN-SP
Exercises
Summary
PHITS講習会　入門実習
Table of Contents 32

33. Summary
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

34. Future Plans 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 34