.. _standalone-example:

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 :math:`^{183}`\ Hf, :math:`^{160m}`\ Tm, :math:`^{169}`\ Ta, and :math:`^{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