added nuc data

tasks/task_06_CSG_cell_tally_DPA/1_find_dpa.ipynb

@@ -27,7 +27,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "This first stage sets up the geometry and materials for the simulation."
+    "First import OpenMC and configure the nuclear data path"
    ]
   },
   {
@@ -38,7 +38,24 @@
    "source": [
     "import openmc\n",
     "\n",
-    "\n",
+    "# Setting the cross section path to the correct location in the docker image.\n",
+    "# If you are running this outside the docker image you will have to change this path to your local cross section path.\n",
+    "openmc.config['cross_sections'] = '/nuclear_data/cross_sections.xml'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "This first stage sets up the geometry and materials for the simulation."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
     "# MATERIALS\n",
     "\n",
     "density_of_iron_in_g_per_cm3 = 7.75\n",