4.14. Example: Standalone DCHAIN use (without PHITS)

While DCHAIN is principally intended to be used alongside the [T-Dchain] tally in PHITS, it can be used in a standalone fashion without PHITS whatsoever for simple decay calculations where the [T-Track] and [T-Yield] outputs of PHITS would be ignored anyways. To do this, a few parameters must be changed from their DCHAIN default values, and the dch_link.dat file, which is just a single line containing the file path to the DCHAIN data folder (default shown below), must also be present in the directory.

c:/phits/dchain-sp/data/

Below is an example input where the decay of \(^{183}\)Hf, \(^{160m}\)Tm, \(^{169}\)Ta, and \(^{164}\)Hf, each starting with an activity of 1 MBq, is assessed at a variety of times over 10 days of decay. This example only includes the most essential/useful parameters one is likely to be concerned with in this scenario; of course, other desired output parameters can be added. The comments point out which values are most important for modifying. In principle, setting jmode= -1, inmtcf= 0, and hnfluxs= no are mandatory for standalone calculation; however, setting jmode= -1 alone is sufficient and will cause the other variables to be forcibly overwritten.

htitle = Standalone DCHAIN decay calculation example

  imode =       2        ! output inventory, decay heats, and photon spectra
  jmode =      -1        ! decay only, no external source
idcylib =       5        ! default decay library using data from JENDL and ENDF

  acmin =  1.0000E-20    ! threshold activity [Bq] to appear in *.act output file
 istabl =       0        ! toggle output of stable nuclides
iwrtchn =       1        ! decay chain scheme settings for *.dcs file
chrlvth =  1.0000E-04    !   threshold for determining if chains printed to *.dcs file
iwrchdt =       1        !   add extra information for contribution by reaction

! --- irradiation time ---
 itstep =       1        ! a decay calculation is just a single 'cooling' time step
   10.0   d  0.0         ! this time step must be >= to the final requested output time

! --- output time ---
  itout =       9        ! request times when inventory information is outputted
     1  m
     5  m
     10 m
     30 m
     3  h
     12 h
     1  d
     5  d
     10 d

! --- irradiation condition ---
 inmtcf =       0       ! set to 0 so DCHAIN won't look for [T-Yield] file

! --- calculation region details ---
 iregon =      1
!1)HRGCMM 2)IREGS 3)ITGNCLS 4)FLUXS 5)HNFLUXS 6)VOLUMES
DUMMY001  -1  4  0.0  no  1.0E+0 ! 4 nuclides to be tracked; set HNFLUXS to 'no' so
Hf-183       b1.00E+06           !  DCHAIN won't look for [T-Track] file; vol = 1 cm^3.
Tm-160m      b1.00E+06           ! Inventory is normally in 1E24 atoms/cm^3, but putting
Ta-169       b1.00E+06           ! 'b' before the value changes it to an activity in Bq.
Hf-164       b1.00E+06           !  Here each nuclide has a starting activity of 1 MBq.

end