Unstructured Grids and the Multigroup Neutron Diffusion Equation

<table class="table-group" width="800px"><tr class="fig-image" id="a"><td><img alt="641863.fig.006a" src="https://static.hindawi.com/articles/stni/volume-2013/641863/figures/641863.fig.006a.jpg"/></td></tr><tr class="fig-caption"><td align="center"><table><tr><td><b>(a) </b>Fast flux distribution</td></tr></table></td></tr><tr class="fig-image" id="b"><td><img alt="641863.fig.006b" src="https://static.hindawi.com/articles/stni/volume-2013/641863/figures/641863.fig.006b.jpg"/></td></tr><tr class="fig-caption"><td align="center"><table><tr><td><b>(b) </b>Fast flux unknowns</td></tr></table></td></tr><tr class="fig-image" id="c"><td><img alt="641863.fig.006c" src="https://static.hindawi.com/articles/stni/volume-2013/641863/figures/641863.fig.006c.jpg"/></td></tr><tr class="fig-caption"><td align="center"><table><tr><td><b>(c) </b>Matrix <svg height="11.3125" id="M89" style="vertical-align:-0.1092pt" version="1.1" viewbox="0 0 11.075 11.3125" width="11.075" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
<g transform="matrix(.017,-0,0,-.017,.062,11.113)"><path d="M627 18l-10 -26q-79 6 -116 27t-69 76q-41 71 -71 138q-13 29 -27.5 39t-42.5 10h-46l-27 -145q-13 -74 -2.5 -88.5t78.5 -20.5l-6 -28h-271l5 28q66 6 82.5 21.5t30.5 87.5l71 387q12 66 2 78.5t-77 19.5l8 28h233q102 0 147 -29q65 -43 65 -129q0 -69 -45.5 -117
t-115.5 -72q40 -86 66 -133q39 -68 65 -101q28 -37 73 -51zM491 483q0 67 -33.5 101t-91.5 34q-35 0 -51 -10q-13 -8 -20 -48l-45 -245h49q71 0 113 28q79 52 79 140z" id="x1D445"></path></g>
</svg> structure</td></tr></table></td></tr><tr class="fig-image" id="d"><td><img alt="641863.fig.006d" src="https://static.hindawi.com/articles/stni/volume-2013/641863/figures/641863.fig.006d.jpg"/></td></tr><tr class="fig-caption"><td align="center"><table><tr><td><b>(d) </b>Matrix <svg height="11.175" id="M90" style="vertical-align:-0.0pt" version="1.1" viewbox="0 0 10.7 11.175" width="10.7" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
<g transform="matrix(.017,-0,0,-.017,.062,11.113)"><path d="M599 650l-18 -160l-30 -2q-2 70 -11 94q-5 16 -26 24t-75 8h-94q-27 0 -33.5 -6.5t-12.5 -32.5l-43 -226h108q52 0 72.5 5t31 18t28.5 52h28l-40 -200h-28q-1 42 -6 56.5t-24.5 21t-70.5 6.5h-108l-32 -177q-13 -65 1 -80.5t88 -22.5l-8 -28h-279l6 28q61 5 77.5 20.5
t29.5 81.5l72 387l7.5 40.5t1 26.5t-4 18t-15.5 10t-24 6t-37 4l8 28h461z" id="x1D439"></path></g>
</svg> structure</td></tr></table></td></tr></table>

<table>A bare homogeneous circle solved with finite elements (218 unknowns).</table>

Science and Technology of Nuclear Installations

Unstructured Grids and the Multigroup Neutron Diffusion Equation

Figure 6