Fusion neutronics workshop

with OpenMC

Dr Jonathan Shimwell.

Jonathan.Shimwell@ukaea.uk

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

Neutron birth

(n,n')

(n,f)

(n,n')

(γ,γ')

(n,nγ')

(n,pn')

(n,f)

(n,2n)

(n,α)

(n,γ)

this presentation has moved to

https://slides.com/neutronics_workshop/neutronics_workshop

Neutronics analysis has a role in assessing the functionality and viability of nuclear reactor designs, particle accelerators, radiation shielding, medical treatment devices, etc

Neutronics analysis also has uses in fusion reactor design and can ascertain:

• The tritium breeding ratio (TBR)
• Activation of material and resulting radioactivity
• Biological dose rates
• Deposited heat within components
• Material damage (e.g DPA or Helium production)

  How can neutronics help

Cross section data is key to the neutronics workflow and provide us with the likelihood of a particular interaction.

 Interaction cross sections

Availability of experimental data varies.

Typically the experimental data is then interpreted to create evaluation libraries, such as ENDF, JEFF, JENDL, CENDL.

Cross sections can be measured experimentally with monoenergetic neutrons.

 Interaction cross sections

Cross section evaluations exist for different isotopes and different interactions.

 Interaction cross sections

A list of interactions is available online

MT numbers using in this workshop include:

• DPA 444
• n,Xt 205

 Making materials

 Making materials

 Making materials

import openmc

mat1 = openmc.Material(name='natural L2O')

mat1.add_element('Li', 2)

mat1.add_element('O', 1)

mat.density = 2.01

mat2 = openmc.Material(name='enriched Li20')

mat2.add_nuclide('Li6', 0.6*2)

mat2.add_nuclide('Li7', 0.4*2)

mat2.add_nuclide('O16', 0.9976206)

mat2.add_nuclide('O17', 0.000379)

mat2.add_nuclide('O18', 0.0020004)

 Making geometry

 Making surfaces

surface_xp = openmc.XPlane(x0=0)
surface_yp = openmc.YPlane(y0=0)
surface_zp = openmc.ZPlane(z0=0)
surface_p = openmc.Plane(A=1.0, B=0.0, C=0.0, D=0.0)
surface_xcy = openmc.XCylinder(y0=0.0, z0=0.0, R=1.0)
surface_ycy = openmc.YCylinder(x0=0.0, z0=0.0, R=1.0)
surface_zcy = openmc.ZCylinder(x0=0.0, z0=0.0, R=1.0)
surface_s = openmc.Sphere(x0=0.0, y0=0.0, z0=0.0, R=1.0)
surface_xco = openmc.XCone(x0=0.0, y0=0.0, z0=0.0, R2=1.0)
surface_yco = openmc.YCone(x0=0.0, y0=0.0, z0=0.0, R2=1.0)
surface_zco = openmc.ZCone( x0=0.0, y0=0.0, z0=0.0, R2=1.0)
surface_quad = openmc.Quadric(a=0.0, b=0.0, c=0.0, d=0.0, e=0.0, f=0.0, g=0.0, h=0.0, j=0.0, k=0.0)

The geometry of a model in OpenMC is defined using constructive solid geometry (CSG) although CAD is supported via DAGMC

 Making geometry

 Making volumes

surface_sphere = openmc.Sphere(r=10.0)
region_inside_sphere = -surface_sphere
cell_sphere = openmc.Cell(region=region_inside_sphere) 

cell_sphere.fill = steel

surf_sphere1 = openmc.Sphere(r=10.0)

surf_sphere2 = openmc.Sphere(r=20.0)

region_inside_sphere = +surf_sphere1 & -surf_sphere2

cell = openmc.Cell(region= region_inside_sphere) 

cell_sphere.fill = steel

 Making geometry

 Making volumes          | (union)

surf_sphere1 = openmc.Sphere(r=10.0)

surf_sphere2 = openmc.Sphere(r=20.0)

surf_cy = openmc.ZCylinder(r=5)
surf_up_zp = openmc.ZPlane(z0=30)

surf_low_zp = openmc.ZPlane(z0=-30)

hollow_sph = ( +surf_sphere1 & -surf_sphere2)

capped_cy = ( -surf_cy & -surf_up_zp & +surf_low_zp)

            
cell = openmc.Cell(region = hollow_sph | capped_cy) 

cell_sphere.fill = steel

 Making geometry

 Making volumes         & (intersection)

surf_sphere1 = openmc.Sphere(r=10.0)

surf_sphere2 = openmc.Sphere(r=20.0)

surf_cy = openmc.ZCylinder(r=5)
surf_up_zp = openmc.ZPlane(z0=30)

surf_low_zp = openmc.ZPlane(z0=-30)

hollow_sph = ( +surf_sphere1 & -surf_sphere2)

capped_cy = ( -surf_cy & -surf_up_zp & +surf_low_zp)

            
cell = openmc.Cell(region = hollow_sph & capped_cy) 

cell_sphere.fill = steel

 Making geometry

 Making volumes          ~ (complement)

surf_sphere1 = openmc.Sphere(r=10.0)

surf_sphere2 = openmc.Sphere(r=20.0)

surf_cy = openmc.ZCylinder(r=5)
surf_up_zp = openmc.ZPlane(z0=30)

surf_low_zp = openmc.ZPlane(z0=-30)

hollow_sph = ( +surf_sphere1 & -surf_sphere2)

capped_cy = ( -surf_cy & -surf_up_zp & +surf_low_zp)

            
cell = openmc.Cell(region = hollow_sph ~ capped_cy) 

cell_sphere.fill = steel

Task 1

Cross section plotting

Plot reactions for isotopes, elements or materials

Task 2

Building and visualizing the model geometry

Construct geometry and view it in 2D or 3D

Task 4

Finding the neutron flux

Task 5

Finding the neutron spectra

Task 6

Finding the tritium production

Task 7

Finding the neutron damage

The DPA tally will just produce a single number

Task 8

Optimize a breeder blanket

for tritium production