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

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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

29

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