TRITON and tungsten

[Jeremy]

I have a TRITON model for a sample matrix that contains tungsten as a trace component.  When I try to run it under SCALE 6.1.3, I get the following message:

mip message number mp-281 follows:

 ***error***   this standard composition called for natural element w (74000) which does not exist on this cross section library.   isotope w-180 (74180) occurs naturally with a weight fraction of  1.17458E-03 but also does not exist on this cross section library.

please specify modified abundances for this element so that this isotope is not used.

Tungsten does not exist?

Jeremy

[Steve Skutnik]

Hi Jeremy,

When you specify tungsten as just 74000, TRITON tries to populate out the natural abundances (which comes out to a mixture of W-180, W-182, W-183, W-184, and W-186). The problem however is that TRITON does not have neutron reaction cross-sections for W-180; ergo, what you need to do if you wish to specify tungsten is to directly specify the fractions of the other isotopes (W-182, W-183, W-184, and W-186).

-Steve

[Jeremy]

Has this issue been eliminated in SCALE 6.2.2?

[Steve Skutnik]

I believe (and Matt or Will can correct me on this one if I'm wrong) that in 6.2, TRITON will issue a warning for any isotopes lacking natural abundance data but will proceed with the calculation. (O-18 for example also has this issue.)