Seth Robison
I'm working on a project where spent fuel is being shielded by a concrete wall of varying thickness. I have source terms developed in ORIGEN-ARP, but I'm struggling to figure out how to define them in MAVRIC's GeeWiz interface. I think I have the source strength set, but the bins and their PDF is confusing me.
Also Figure S6.5.5 in the 6.1 manual is labeled emission probability/eV on the ordinate while the 6.2 manual has it labeled as probability density function (Figure 4.1.10). The values labeled "probability density function" (in the 6.2 manual) don't match up with the values in Tables 6.5.1 and 4.1.9 which are what are used as the "TruePDF" values in the actual input file. That gave me a headache.
EDIT: I've been reading the manual more and found the definitions section in the Monaco chapter. It looks like the way I'm supposed to do it is by importing a .f71 file from ORIGEN. I have gotten ORIGEN to produce the file, but now I don't know how to how to import it into MAVRIC. Table F23.3.4 in the manual says"origensBinaryConcentrationFile" u c s Spectrum from an ORIGEN-S binary concentration file, located on unit u, case number c, spectra type s. For the spectra type s, values are: 1 - photons from light elements, 2 – photons from actinides, 3 – photons from fission products, 4 – master photon library, 5 – total neutron, 6 – (α,n) spectrum, and 7- spontaneous fission neutrons." and then in the isfsi example it has "parameters = 71 64 4" but I don't see a unit 71 or case 64 anywhere in the input file. What exactly does it mean located on unit u? How does it even know which .f71 file to use? All I've found so far about ORIGEN concentration sources in Monaco is the brief paragraph right under table F23.3.4.
Figure 1: Distributions "Function Pairs" interface
Figure 2: ARP bins and photons/sec
Figure 3: Distributions "Histogram" Interface
peplowde
In SCALE 6.1, the easiest way to use an ORIGEN spectrum is to access the binary concentration (*.f71) file directly. The manual describes how to create a distribution with the special="origensBinaryConcentrationFile" keyword which can then be used by a source object as the energy distribution. You can get the total source strength from the ORIGEN output, it is simply the sum of all of the individual groups.
In SCALE 6.2, the ability to use several different ORIGEN binary concentration (*.f71) files at once and the total strength can also be read from the file. Note that the format of the ORIGEN binary concentration file has changed from 6.1 to 6.2, so the parameters used in the Monaco/MAVRIC distribution definition have changed – see the manuals for details.
As the manual discusses, there are two types of distributions – histogram or value/function pairs. Histograms have N+1 energy boundaries for N bins. Value/function pairs have N energies with the N corresponding function values. ORIGEN gamma data will be a histogram. In the text input, one needs to list the N+1 energies (in eV) with the ‘abscissa’ keyword and the amounts in each bin with the ‘truePDF’ keyword. Monaco/MAVRIC will normalize the values into a pdf, or you can divide by the total before entry. If you are using the same group structure in both the ORIGEN and Monaco/MAVRIC, then you can use the keyword ‘photonBounds’ instead of listing the abscissa values. When using ‘photonBounds’ or ‘neutronBounds’, be sure to list the bins in order from high-energy to low-energy.
Note that the figures in the manual that you referred to are correct – in the plots the data is shown as probability distribution functions, meaning the bin values (listed in the tables) have been divided by bin widths (in eV). This is standard practice in mathematics and makes the plots look more physical – the area under the curve is 1 and there are not sharp drops due to skinny bins or large plateaus from large bins.
Douglas
Monaco/MAVRIC team
peplowde
In SCALE 6.1, to use the special="origensBinaryConcentrationFile", first use a ‘shell’ command to copy the binary concentration (*.f71) file from your ORIGEN run into the SCALE working directory. Something like this:
=shell
copy C:\Users\seth\Documents\somewhere\something.f71 ft71ft01
end
In the ORIGEN input, you told ORIGEN how many time steps to save to this file – that corresponds to cases. Then, in your Monaco/MAVRIC input, create a distribution that uses the binary concentration file (now as unit 71). Something like this:
distribution 1
special="origensBinaryConcentrationFile"
parameters 71 c s end
end distribution
where c is the case number (usually the last) and s is the type of data you want (4 is photon, 5 is neutron, etc). Then you source uses eDistributionID=1 and a strength with the total number emitted. SCALE 6.2 is a bit more powerful, with different syntax and can remember the total strength.
Douglas
Monaco/MAVRIC team