DAGMC NBI

Shutdown dose rate

Jonathan Shimwell

This work was funded by the RCUK Energy Programme
[Grant number EP/P012450/1]

Work flow

CAD geometry

Clean CAD geometry

Material assignment

Unstructured mesh

Neutron transport

Material transmutation

Gamma source creation

Gamma source transport

Faceted geometry

Dose map

Clean CAD geometry          

Remove overlaps and other geometry errors

Removal of splines is not necessary

Creation of void space is not necessary

Add detail to geometry          

Added detail to the magnets, divertor and vacuum vessel

Export each material as a separate file

Material assignment   

Import each material from a separate file

JSON control file with knowledge of each geometry file and allocated material

Creation of materials in Pyne

Material assignment   

Faceted geometry

Imprint & merge functions are applied to the complete geometry.

 

This speeds up particle transport as current volume and material can be found quickly

Faceted geometry

Creating a 315 degree wedge and imprinting & merging this with the geometry allows the reflecting surfaces to be found automatically

reflecting surfaces

geometry colored by material

315 degree wedge

Faceted geometry

Unstructured geometry

Void fraction?

M2 fraction?

M1 fraction?

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Implicit void

M2 fraction=1

M1 fraction=1

Activation tallies conform to the material boundaries

 

Gamma ource generation occurs in the correct material

 

Less "correction" routines required

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Neutron activation tally   

Tally the neutron spectra on each element in the unstructured mesh (175 energy groups)

 

Current model contains 8 million unstructured elements

 

Neutrons are not transported on the unstructured mesh, just tallied

Material transmutation  

Material specification each mesh element from a single source

Neutron spectra for the 8 million tet mesh elements

Gamma source for activated products

ALARA or FISPACT-II

Nuclear data read once and kept in memory for subsequent inventory calculations.

Reduced file reading and writing operations.

Easy to parallelize

Pyne

Conclusion

Awaiting updated CAD model of NBI with materials identified

 

Building work flow and testing the work flow on old model in the mean time

 

Modifications have been carried out for:

DAGMC - to improve MCNP6 support

              - altered mesh tally format

Trelis - automated Python scripts for reading geometry, meshing

            assigning, materials, tallies and producing h5 geometry files

Pyne - inclusion of tallies which require the material number

MCR2S - ability to read tet mesh tallies from DAGMC (Tim Eade)

Pyne material examples

Material example defined with elements and isotopes

Material example defined with elements and isotopes

Neutronics meeting 2018

By Jonathan Shimwell

Neutronics meeting 2018

DAGMC NBI update

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