diff --git a/Dockerfile b/Dockerfile
index 6466c7685..478dfc495 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -30,7 +30,7 @@ RUN git clone https://github.com/njoy/NJOY2016 /opt/NJOY2016 && \
 # Clone and install OpenMC
 RUN git clone https://github.com/openmc-dev/openmc.git /opt/openmc && \
     cd /opt/openmc && mkdir -p build && cd build && \
-    cmake  -Doptimize=on -DHDF5_PREFER_PARALLEL=on .. && \
+    cmake -Doptimize=on -DHDF5_PREFER_PARALLEL=on .. && \
     make && make install && \
     cd .. && pip install -e .[test]
 
diff --git a/openmc/_xml.py b/openmc/_xml.py
index 9c6c219e2..7470b2c3b 100644
--- a/openmc/_xml.py
+++ b/openmc/_xml.py
@@ -1,6 +1,6 @@
 def clean_indentation(element, level=0, spaces_per_level=2):
     """
-    copy and paste from http://effbot.org/zone/elementent-lib.htm#prettyprint
+    copy and paste from http://effbot.org/zone/element-lib.htm#prettyprint
     it basically walks your tree and adds spaces and newlines so the tree is
     printed in a nice way
     """
diff --git a/openmc/cell.py b/openmc/cell.py
index ee883c796..06a80e173 100644
--- a/openmc/cell.py
+++ b/openmc/cell.py
@@ -2,7 +2,7 @@ from collections import OrderedDict
 from collections.abc import Iterable
 from copy import deepcopy
 from math import cos, sin, pi
-from numbers import Real, Integral
+from numbers import Real
 from xml.etree import ElementTree as ET
 import sys
 import warnings
@@ -442,7 +442,7 @@ class Cell(IDManagerMixin):
         if memo is None:
             memo = {}
 
-        # If no nemoize'd clone exists, instantiate one
+        # If no memoize'd clone exists, instantiate one
         if self not in memo:
             # Temporarily remove paths
             paths = self._paths
diff --git a/openmc/checkvalue.py b/openmc/checkvalue.py
index cbeac9c37..e19780a1c 100644
--- a/openmc/checkvalue.py
+++ b/openmc/checkvalue.py
@@ -90,7 +90,7 @@ def check_iterable_type(name, value, expected_type, min_depth=1, max_depth=1):
 
         # Get a string representation of the current index in case we raise an
         # exception.
-        form = '[' + '{:d}, '*(len(index)-1) + '{:d}]'
+        form = '[' + '{:d}, ' * (len(index)-1) + '{:d}]'
         ind_str = form.format(*index)
 
         # What is the current item we are looking at?
@@ -109,7 +109,7 @@ def check_iterable_type(name, value, expected_type, min_depth=1, max_depth=1):
             index[-1] += 1
 
         # If this item is not of the expected type, then it's either an error or
-        # another level of the tree that we need to pursue deeper.
+        # on a deeper level of the tree.
         else:
             if isinstance(current_item, Iterable):
                 # The tree goes deeper here, let's explore it.
diff --git a/openmc/cmfd.py b/openmc/cmfd.py
index b215d2058..5f4f6e60e 100644
--- a/openmc/cmfd.py
+++ b/openmc/cmfd.py
@@ -64,7 +64,7 @@ class CMFDMesh(object):
         The lower-left corner of the structured mesh. If only two coordinates
         are given, it is assumed that the mesh is an x-y mesh.
     upper_right : Iterable of float
-        The upper-right corner of the structrued mesh. If only two coordinates
+        The upper-right corner of the structured mesh. If only two coordinates
         are given, it is assumed that the mesh is an x-y mesh.
     dimension : Iterable of int
         The number of mesh cells in each direction.
@@ -220,7 +220,7 @@ class CMFDRun(object):
         Indicate whether an effective downscatter cross section should be used
         when using 2-group CMFD.
     feedback : bool
-        Indicate or not the CMFD diffusion result is used to adjust the weight
+        Indicate whether or not the CMFD diffusion result is used to adjust the weight
         of fission source neutrons on the next OpenMC batch. Defaults to False.
     cmfd_ktol : float
         Tolerance on the eigenvalue when performing CMFD power iteration
@@ -694,7 +694,7 @@ class CMFDRun(object):
     def run(self, **kwargs):
         """Run OpenMC with coarse mesh finite difference acceleration
 
-        This method is called by user to run CMFD once instance variables of
+        This method is called by the user to run CMFD once instance variables of
         CMFDRun class are set
 
         Parameters
diff --git a/openmc/data/grid.py b/openmc/data/grid.py
index e63919ac2..6aec569dc 100644
--- a/openmc/data/grid.py
+++ b/openmc/data/grid.py
@@ -2,7 +2,7 @@ import numpy as np
 
 
 def linearize(x, f, tolerance=0.001):
-    """Return a tabulated representation of a function of one variable.
+    """Return a tabulated representation of a one-variable function
 
     Parameters
     ----------
diff --git a/openmc/data/laboratory.py b/openmc/data/laboratory.py
index cfedb292b..10403655d 100644
--- a/openmc/data/laboratory.py
+++ b/openmc/data/laboratory.py
@@ -4,9 +4,8 @@ from numbers import Real, Integral
 import numpy as np
 
 import openmc.checkvalue as cv
-from openmc.stats import Tabular, Univariate, Discrete, Mixture
+from openmc.stats import Tabular, Univariate, Discrete
 from .angle_energy import AngleEnergy
-from .function import INTERPOLATION_SCHEME
 from .endf import get_tab2_record, get_tab1_record
 
 
@@ -122,7 +121,7 @@ class LaboratoryAngleEnergy(AngleEnergy):
         mu = []
         energy_out = []
         for i in range(ne):
-            params, tab2mu = get_tab2_record(file_obj)
+            params, _ = get_tab2_record(file_obj)
             energy[i] = params[1]
             n_mu = params[5]
             mu_i = np.zeros(n_mu)
diff --git a/openmc/data/library.py b/openmc/data/library.py
index d5f18aa17..2339ca1c9 100644
--- a/openmc/data/library.py
+++ b/openmc/data/library.py
@@ -6,7 +6,6 @@ import h5py
 
 from openmc.mixin import EqualityMixin
 from openmc._xml import clean_indentation
-from openmc.checkvalue import check_type
 
 
 class DataLibrary(EqualityMixin):
diff --git a/openmc/data/neutron.py b/openmc/data/neutron.py
index 7420387da..06ba86f4d 100644
--- a/openmc/data/neutron.py
+++ b/openmc/data/neutron.py
@@ -85,7 +85,7 @@ class IncidentNeutron(EqualityMixin):
     resonance_covariance : openmc.data.ResonanceCovariance or None
         Covariance for resonance parameters
     temperatures : list of str
-        List of string representations the temperatures of the target nuclide
+        List of string representations of the temperatures of the target nuclide
         in the data set.  The temperatures are strings of the temperature,
         rounded to the nearest integer; e.g., '294K'
     kTs : Iterable of float
@@ -410,7 +410,7 @@ class IncidentNeutron(EqualityMixin):
         ----------
         path : str
             Path to write HDF5 file to
-        mode : {'r', r+', 'w', 'x', 'a'}
+        mode : {'r', 'r+', 'w', 'x', 'a'}
             Mode that is used to open the HDF5 file. This is the second argument
             to the :class:`h5py.File` constructor.
         libver : {'earliest', 'latest'}
diff --git a/openmc/data/photon.py b/openmc/data/photon.py
index 31514639a..5a9883992 100644
--- a/openmc/data/photon.py
+++ b/openmc/data/photon.py
@@ -794,7 +794,7 @@ class IncidentPhoton(EqualityMixin):
         ----------
         path : str
             Path to write HDF5 file to
-        mode : {'r', r+', 'w', 'x', 'a'}
+        mode : {'r', 'r+', 'w', 'x', 'a'}
             Mode that is used to open the HDF5 file. This is the second argument
             to the :class:`h5py.File` constructor.
         libver : {'earliest', 'latest'}
diff --git a/openmc/data/product.py b/openmc/data/product.py
index 5b8652d77..a6ea17bf9 100644
--- a/openmc/data/product.py
+++ b/openmc/data/product.py
@@ -17,7 +17,7 @@ class Product(EqualityMixin):
     Parameters
     ----------
     particle : str, optional
-        What particle the reaction product is. Defaults to 'neutron'.
+        The particle type of the reaction product. Defaults to 'neutron'.
 
     Attributes
     ----------
diff --git a/openmc/deplete/chain.py b/openmc/deplete/chain.py
index a2f7db818..662106a69 100644
--- a/openmc/deplete/chain.py
+++ b/openmc/deplete/chain.py
@@ -108,16 +108,37 @@ def replace_missing(product, decay_data):
 
 
 _SECONDARY_PARTICLES = {
-    "(n,p)": ["H1"], "(n,d)": ["H2"], "(n,t)": ["H3"], "(n,3He)": ["He3"],
-    "(n,a)": ["He4"], "(n,2nd)": ["H2"], "(n,na)": ["He4"], "(n,3na)": ["He4"],
-    "(n,n3a)": ["He4"] * 3, "(n,2na)": ["He4"], "(n,np)": ["H1"],
-    "(n,n2a)": ["He4"] * 2, "(n,2n2a)": ["He4"] * 2, "(n,nd)": ["H2"],
-    "(n,nt)": ["H3"], "(n,nHe-3)": ["He3"], "(n,nd2a)": ["H2", "He4"],
-    "(n,nt2a)": ["H3", "He4", "He4"], "(n,2np)": ["H1"], "(n,3np)": ["H1"],
-    "(n,n2p)": ["H1"] * 2, "(n,2a)": ["He4"] * 2, "(n,3a)": ["He4"] * 3,
-    "(n,2p)": ["H1"] * 2, "(n,pa)": ["H1", "He4"],
-    "(n,t2a)": ["H3", "He4", "He4"], "(n,d2a)": ["H2", "He4", "He4"],
-    "(n,pd)": ["H1", "H2"], "(n,pt)": ["H1", "H3"], "(n,da)": ["H2", "He4"]}
+    '(n,p)': ['H1'],
+    '(n,d)': ['H2'],
+    '(n,t)': ['H3'],
+    '(n,3He)': ['He3'],
+    '(n,a)': ['He4'],
+    '(n,2nd)': ['H2'],
+    '(n,na)': ['He4'],
+    '(n,3na)': ['He4'],
+    '(n,n3a)': ['He4'] * 3,
+    '(n,2na)': ['He4'],
+    '(n,np)': ['H1'],
+    '(n,n2a)': ['He4'] * 2,
+    '(n,2n2a)': ['He4'] * 2,
+    '(n,nd)': ['H2'],
+    '(n,nt)': ['H3'],
+    '(n,nHe-3)': ['He3'],
+    '(n,nd2a)': ['H2', 'He4'],
+    '(n,nt2a)': ['H3', 'He4', 'He4'],
+    '(n,2np)': ['H1'],
+    '(n,3np)': ['H1'],
+    '(n,n2p)': ['H1'] * 2,
+    '(n,2a)': ['He4'] * 2,
+    '(n,3a)': ['He4'] * 3,
+    '(n,2p)': ['H1'] * 2,
+    '(n,pa)': ['H1', 'He4'],
+    '(n,t2a)': ['H3', 'He4', 'He4'],
+    '(n,d2a)': ['H2', 'He4', 'He4'],
+    '(n,pd)': ['H1', 'H2'],
+    '(n,pt)': ['H1', 'H3'],
+    '(n,da)': ['H2', 'He4']
+}
 
 
 class Chain(object):
diff --git a/openmc/deplete/reaction_rates.py b/openmc/deplete/reaction_rates.py
index 85c8d8998..b1dc5b13f 100644
--- a/openmc/deplete/reaction_rates.py
+++ b/openmc/deplete/reaction_rates.py
@@ -26,7 +26,7 @@ class ReactionRates(np.ndarray):
     reactions : list of str
         Transmutation reactions being tracked
     from_results : boolean
-        If the reaction rates are loaded from results, indexing dictionnaries
+        If the reaction rates are loaded from results, indexing dictionaries
         need to be kept the same.
 
     Attributes
@@ -66,7 +66,7 @@ class ReactionRates(np.ndarray):
             obj.index_rx = reactions
         # Else, assumes that reaction rates are ordered the same way as
         # the lists of local_mats, nuclides and reactions (or keys if these
-        # are dictionnaries)
+        # are dictionaries)
         else:
             obj.index_mat = {mat: i for i, mat in enumerate(local_mats)}
             obj.index_nuc = {nuc: i for i, nuc in enumerate(nuclides)}
diff --git a/openmc/element.py b/openmc/element.py
index 5b2a878a8..e36460334 100644
--- a/openmc/element.py
+++ b/openmc/element.py
@@ -3,7 +3,6 @@ import re
 import os
 from xml.etree import ElementTree as ET
 
-import openmc
 import openmc.checkvalue as cv
 from openmc.data import NATURAL_ABUNDANCE, atomic_mass
 
diff --git a/openmc/examples.py b/openmc/examples.py
index 4e8c8cf92..3b73d043f 100644
--- a/openmc/examples.py
+++ b/openmc/examples.py
@@ -25,25 +25,25 @@ def pwr_pin_cell():
     # Define materials.
     fuel = openmc.Material(name='UO2 (2.4%)')
     fuel.set_density('g/cm3', 10.29769)
-    fuel.add_nuclide("U234", 4.4843e-6)
-    fuel.add_nuclide("U235", 5.5815e-4)
-    fuel.add_nuclide("U238", 2.2408e-2)
-    fuel.add_nuclide("O16", 4.5829e-2)
+    fuel.add_nuclide('U234', 4.4843e-6)
+    fuel.add_nuclide('U235', 5.5815e-4)
+    fuel.add_nuclide('U238', 2.2408e-2)
+    fuel.add_nuclide('O16', 4.5829e-2)
 
     clad = openmc.Material(name='Zircaloy')
     clad.set_density('g/cm3', 6.55)
-    clad.add_nuclide("Zr90", 2.1827e-2)
-    clad.add_nuclide("Zr91", 4.7600e-3)
-    clad.add_nuclide("Zr92", 7.2758e-3)
-    clad.add_nuclide("Zr94", 7.3734e-3)
-    clad.add_nuclide("Zr96", 1.1879e-3)
+    clad.add_nuclide('Zr90', 2.1827e-2)
+    clad.add_nuclide('Zr91', 4.7600e-3)
+    clad.add_nuclide('Zr92', 7.2758e-3)
+    clad.add_nuclide('Zr94', 7.3734e-3)
+    clad.add_nuclide('Zr96', 1.1879e-3)
 
     hot_water = openmc.Material(name='Hot borated water')
     hot_water.set_density('g/cm3', 0.740582)
-    hot_water.add_nuclide("H1", 4.9457e-2)
-    hot_water.add_nuclide("O16", 2.4672e-2)
-    hot_water.add_nuclide("B10", 8.0042e-6)
-    hot_water.add_nuclide("B11", 3.2218e-5)
+    hot_water.add_nuclide('H1', 4.9457e-2)
+    hot_water.add_nuclide('O16', 2.4672e-2)
+    hot_water.add_nuclide('B10', 8.0042e-6)
+    hot_water.add_nuclide('B11', 3.2218e-5)
     hot_water.add_s_alpha_beta('c_H_in_H2O')
 
     # Define the materials file.
@@ -106,148 +106,148 @@ def pwr_core():
     # Define materials.
     fuel = openmc.Material(1, name='UOX fuel')
     fuel.set_density('g/cm3', 10.062)
-    fuel.add_nuclide("U234", 4.9476e-6)
-    fuel.add_nuclide("U235", 4.8218e-4)
-    fuel.add_nuclide("U238", 2.1504e-2)
-    fuel.add_nuclide("Xe135", 1.0801e-8)
-    fuel.add_nuclide("O16", 4.5737e-2)
+    fuel.add_nuclide('U234', 4.9476e-6)
+    fuel.add_nuclide('U235', 4.8218e-4)
+    fuel.add_nuclide('U238', 2.1504e-2)
+    fuel.add_nuclide('Xe135', 1.0801e-8)
+    fuel.add_nuclide('O16', 4.5737e-2)
 
     clad = openmc.Material(2, name='Zircaloy')
     clad.set_density('g/cm3', 5.77)
-    clad.add_nuclide("Zr90", 0.5145)
-    clad.add_nuclide("Zr91", 0.1122)
-    clad.add_nuclide("Zr92", 0.1715)
-    clad.add_nuclide("Zr94", 0.1738)
-    clad.add_nuclide("Zr96", 0.0280)
+    clad.add_nuclide('Zr90', 0.5145)
+    clad.add_nuclide('Zr91', 0.1122)
+    clad.add_nuclide('Zr92', 0.1715)
+    clad.add_nuclide('Zr94', 0.1738)
+    clad.add_nuclide('Zr96', 0.0280)
 
     cold_water = openmc.Material(3, name='Cold borated water')
     cold_water.set_density('atom/b-cm', 0.07416)
-    cold_water.add_nuclide("H1", 2.0)
-    cold_water.add_nuclide("O16", 1.0)
-    cold_water.add_nuclide("B10", 6.490e-4)
-    cold_water.add_nuclide("B11", 2.689e-3)
+    cold_water.add_nuclide('H1', 2.0)
+    cold_water.add_nuclide('O16', 1.0)
+    cold_water.add_nuclide('B10', 6.490e-4)
+    cold_water.add_nuclide('B11', 2.689e-3)
     cold_water.add_s_alpha_beta('c_H_in_H2O')
 
     hot_water = openmc.Material(4, name='Hot borated water')
     hot_water.set_density('atom/b-cm', 0.06614)
-    hot_water.add_nuclide("H1", 2.0)
-    hot_water.add_nuclide("O16", 1.0)
-    hot_water.add_nuclide("B10", 6.490e-4)
-    hot_water.add_nuclide("B11", 2.689e-3)
+    hot_water.add_nuclide('H1', 2.0)
+    hot_water.add_nuclide('O16', 1.0)
+    hot_water.add_nuclide('B10', 6.490e-4)
+    hot_water.add_nuclide('B11', 2.689e-3)
     hot_water.add_s_alpha_beta('c_H_in_H2O')
 
     rpv_steel = openmc.Material(5, name='Reactor pressure vessel steel')
     rpv_steel.set_density('g/cm3', 7.9)
-    rpv_steel.add_nuclide("Fe54", 0.05437098, 'wo')
-    rpv_steel.add_nuclide("Fe56", 0.88500663, 'wo')
-    rpv_steel.add_nuclide("Fe57", 0.0208008, 'wo')
-    rpv_steel.add_nuclide("Fe58", 0.00282159, 'wo')
-    rpv_steel.add_nuclide("Ni58", 0.0067198, 'wo')
-    rpv_steel.add_nuclide("Ni60", 0.0026776, 'wo')
-    rpv_steel.add_nuclide("Mn55", 0.01, 'wo')
-    rpv_steel.add_nuclide("Cr52", 0.002092475, 'wo')
-    rpv_steel.add_nuclide("C0", 0.0025, 'wo')
-    rpv_steel.add_nuclide("Cu63", 0.0013696, 'wo')
+    rpv_steel.add_nuclide('Fe54', 0.05437098, 'wo')
+    rpv_steel.add_nuclide('Fe56', 0.88500663, 'wo')
+    rpv_steel.add_nuclide('Fe57', 0.0208008, 'wo')
+    rpv_steel.add_nuclide('Fe58', 0.00282159, 'wo')
+    rpv_steel.add_nuclide('Ni58', 0.0067198, 'wo')
+    rpv_steel.add_nuclide('Ni60', 0.0026776, 'wo')
+    rpv_steel.add_nuclide('Mn55', 0.01, 'wo')
+    rpv_steel.add_nuclide('Cr52', 0.002092475, 'wo')
+    rpv_steel.add_nuclide('C0', 0.0025, 'wo')
+    rpv_steel.add_nuclide('Cu63', 0.0013696, 'wo')
 
     lower_rad_ref = openmc.Material(6, name='Lower radial reflector')
     lower_rad_ref.set_density('g/cm3', 4.32)
-    lower_rad_ref.add_nuclide("H1", 0.0095661, 'wo')
-    lower_rad_ref.add_nuclide("O16", 0.0759107, 'wo')
-    lower_rad_ref.add_nuclide("B10", 3.08409e-5, 'wo')
-    lower_rad_ref.add_nuclide("B11", 1.40499e-4, 'wo')
-    lower_rad_ref.add_nuclide("Fe54", 0.035620772088, 'wo')
-    lower_rad_ref.add_nuclide("Fe56", 0.579805982228, 'wo')
-    lower_rad_ref.add_nuclide("Fe57", 0.01362750048, 'wo')
-    lower_rad_ref.add_nuclide("Fe58", 0.001848545204, 'wo')
-    lower_rad_ref.add_nuclide("Ni58", 0.055298376566, 'wo')
-    lower_rad_ref.add_nuclide("Mn55", 0.0182870, 'wo')
-    lower_rad_ref.add_nuclide("Cr52", 0.145407678031, 'wo')
+    lower_rad_ref.add_nuclide('H1', 0.0095661, 'wo')
+    lower_rad_ref.add_nuclide('O16', 0.0759107, 'wo')
+    lower_rad_ref.add_nuclide('B10', 3.08409e-5, 'wo')
+    lower_rad_ref.add_nuclide('B11', 1.40499e-4, 'wo')
+    lower_rad_ref.add_nuclide('Fe54', 0.035620772088, 'wo')
+    lower_rad_ref.add_nuclide('Fe56', 0.579805982228, 'wo')
+    lower_rad_ref.add_nuclide('Fe57', 0.01362750048, 'wo')
+    lower_rad_ref.add_nuclide('Fe58', 0.001848545204, 'wo')
+    lower_rad_ref.add_nuclide('Ni58', 0.055298376566, 'wo')
+    lower_rad_ref.add_nuclide('Mn55', 0.0182870, 'wo')
+    lower_rad_ref.add_nuclide('Cr52', 0.145407678031, 'wo')
     lower_rad_ref.add_s_alpha_beta('c_H_in_H2O')
 
     upper_rad_ref = openmc.Material(7, name='Upper radial reflector / Top plate region')
     upper_rad_ref.set_density('g/cm3', 4.28)
-    upper_rad_ref.add_nuclide("H1", 0.0086117, 'wo')
-    upper_rad_ref.add_nuclide("O16", 0.0683369, 'wo')
-    upper_rad_ref.add_nuclide("B10", 2.77638e-5, 'wo')
-    upper_rad_ref.add_nuclide("B11", 1.26481e-4, 'wo')
-    upper_rad_ref.add_nuclide("Fe54", 0.035953677186, 'wo')
-    upper_rad_ref.add_nuclide("Fe56", 0.585224740891, 'wo')
-    upper_rad_ref.add_nuclide("Fe57", 0.01375486056, 'wo')
-    upper_rad_ref.add_nuclide("Fe58", 0.001865821363, 'wo')
-    upper_rad_ref.add_nuclide("Ni58", 0.055815129186, 'wo')
-    upper_rad_ref.add_nuclide("Mn55", 0.0184579, 'wo')
-    upper_rad_ref.add_nuclide("Cr52", 0.146766614995, 'wo')
+    upper_rad_ref.add_nuclide('H1', 0.0086117, 'wo')
+    upper_rad_ref.add_nuclide('O16', 0.0683369, 'wo')
+    upper_rad_ref.add_nuclide('B10', 2.77638e-5, 'wo')
+    upper_rad_ref.add_nuclide('B11', 1.26481e-4, 'wo')
+    upper_rad_ref.add_nuclide('Fe54', 0.035953677186, 'wo')
+    upper_rad_ref.add_nuclide('Fe56', 0.585224740891, 'wo')
+    upper_rad_ref.add_nuclide('Fe57', 0.01375486056, 'wo')
+    upper_rad_ref.add_nuclide('Fe58', 0.001865821363, 'wo')
+    upper_rad_ref.add_nuclide('Ni58', 0.055815129186, 'wo')
+    upper_rad_ref.add_nuclide('Mn55', 0.0184579, 'wo')
+    upper_rad_ref.add_nuclide('Cr52', 0.146766614995, 'wo')
     upper_rad_ref.add_s_alpha_beta('c_H_in_H2O')
 
     bot_plate = openmc.Material(8, name='Bottom plate region')
     bot_plate.set_density('g/cm3', 7.184)
-    bot_plate.add_nuclide("H1", 0.0011505, 'wo')
-    bot_plate.add_nuclide("O16", 0.0091296, 'wo')
-    bot_plate.add_nuclide("B10", 3.70915e-6, 'wo')
-    bot_plate.add_nuclide("B11", 1.68974e-5, 'wo')
-    bot_plate.add_nuclide("Fe54", 0.03855611055, 'wo')
-    bot_plate.add_nuclide("Fe56", 0.627585036425, 'wo')
-    bot_plate.add_nuclide("Fe57", 0.014750478, 'wo')
-    bot_plate.add_nuclide("Fe58", 0.002000875025, 'wo')
-    bot_plate.add_nuclide("Ni58", 0.059855207342, 'wo')
-    bot_plate.add_nuclide("Mn55", 0.0197940, 'wo')
-    bot_plate.add_nuclide("Cr52", 0.157390026871, 'wo')
+    bot_plate.add_nuclide('H1', 0.0011505, 'wo')
+    bot_plate.add_nuclide('O16', 0.0091296, 'wo')
+    bot_plate.add_nuclide('B10', 3.70915e-6, 'wo')
+    bot_plate.add_nuclide('B11', 1.68974e-5, 'wo')
+    bot_plate.add_nuclide('Fe54', 0.03855611055, 'wo')
+    bot_plate.add_nuclide('Fe56', 0.627585036425, 'wo')
+    bot_plate.add_nuclide('Fe57', 0.014750478, 'wo')
+    bot_plate.add_nuclide('Fe58', 0.002000875025, 'wo')
+    bot_plate.add_nuclide('Ni58', 0.059855207342, 'wo')
+    bot_plate.add_nuclide('Mn55', 0.0197940, 'wo')
+    bot_plate.add_nuclide('Cr52', 0.157390026871, 'wo')
     bot_plate.add_s_alpha_beta('c_H_in_H2O')
 
     bot_nozzle = openmc.Material(9, name='Bottom nozzle region')
     bot_nozzle.set_density('g/cm3', 2.53)
-    bot_nozzle.add_nuclide("H1", 0.0245014, 'wo')
-    bot_nozzle.add_nuclide("O16", 0.1944274, 'wo')
-    bot_nozzle.add_nuclide("B10", 7.89917e-5, 'wo')
-    bot_nozzle.add_nuclide("B11", 3.59854e-4, 'wo')
-    bot_nozzle.add_nuclide("Fe54", 0.030411411144, 'wo')
-    bot_nozzle.add_nuclide("Fe56", 0.495012237964, 'wo')
-    bot_nozzle.add_nuclide("Fe57", 0.01163454624, 'wo')
-    bot_nozzle.add_nuclide("Fe58", 0.001578204652, 'wo')
-    bot_nozzle.add_nuclide("Ni58", 0.047211231662, 'wo')
-    bot_nozzle.add_nuclide("Mn55", 0.0156126, 'wo')
-    bot_nozzle.add_nuclide("Cr52", 0.124142524198, 'wo')
+    bot_nozzle.add_nuclide('H1', 0.0245014, 'wo')
+    bot_nozzle.add_nuclide('O16', 0.1944274, 'wo')
+    bot_nozzle.add_nuclide('B10', 7.89917e-5, 'wo')
+    bot_nozzle.add_nuclide('B11', 3.59854e-4, 'wo')
+    bot_nozzle.add_nuclide('Fe54', 0.030411411144, 'wo')
+    bot_nozzle.add_nuclide('Fe56', 0.495012237964, 'wo')
+    bot_nozzle.add_nuclide('Fe57', 0.01163454624, 'wo')
+    bot_nozzle.add_nuclide('Fe58', 0.001578204652, 'wo')
+    bot_nozzle.add_nuclide('Ni58', 0.047211231662, 'wo')
+    bot_nozzle.add_nuclide('Mn55', 0.0156126, 'wo')
+    bot_nozzle.add_nuclide('Cr52', 0.124142524198, 'wo')
     bot_nozzle.add_s_alpha_beta('c_H_in_H2O')
 
     top_nozzle = openmc.Material(10, name='Top nozzle region')
     top_nozzle.set_density('g/cm3', 1.746)
-    top_nozzle.add_nuclide("H1", 0.0358870, 'wo')
-    top_nozzle.add_nuclide("O16", 0.2847761, 'wo')
-    top_nozzle.add_nuclide("B10", 1.15699e-4, 'wo')
-    top_nozzle.add_nuclide("B11", 5.27075e-4, 'wo')
-    top_nozzle.add_nuclide("Fe54", 0.02644016154, 'wo')
-    top_nozzle.add_nuclide("Fe56", 0.43037146399, 'wo')
-    top_nozzle.add_nuclide("Fe57", 0.0101152584, 'wo')
-    top_nozzle.add_nuclide("Fe58", 0.00137211607, 'wo')
-    top_nozzle.add_nuclide("Ni58", 0.04104621835, 'wo')
-    top_nozzle.add_nuclide("Mn55", 0.0135739, 'wo')
-    top_nozzle.add_nuclide("Cr52", 0.107931450781, 'wo')
+    top_nozzle.add_nuclide('H1', 0.0358870, 'wo')
+    top_nozzle.add_nuclide('O16', 0.2847761, 'wo')
+    top_nozzle.add_nuclide('B10', 1.15699e-4, 'wo')
+    top_nozzle.add_nuclide('B11', 5.27075e-4, 'wo')
+    top_nozzle.add_nuclide('Fe54', 0.02644016154, 'wo')
+    top_nozzle.add_nuclide('Fe56', 0.43037146399, 'wo')
+    top_nozzle.add_nuclide('Fe57', 0.0101152584, 'wo')
+    top_nozzle.add_nuclide('Fe58', 0.00137211607, 'wo')
+    top_nozzle.add_nuclide('Ni58', 0.04104621835, 'wo')
+    top_nozzle.add_nuclide('Mn55', 0.0135739, 'wo')
+    top_nozzle.add_nuclide('Cr52', 0.107931450781, 'wo')
     top_nozzle.add_s_alpha_beta('c_H_in_H2O')
 
     top_fa = openmc.Material(11, name='Top of fuel assemblies')
     top_fa.set_density('g/cm3', 3.044)
-    top_fa.add_nuclide("H1", 0.0162913, 'wo')
-    top_fa.add_nuclide("O16", 0.1292776, 'wo')
-    top_fa.add_nuclide("B10", 5.25228e-5, 'wo')
-    top_fa.add_nuclide("B11", 2.39272e-4, 'wo')
-    top_fa.add_nuclide("Zr90", 0.43313403903, 'wo')
-    top_fa.add_nuclide("Zr91", 0.09549277374, 'wo')
-    top_fa.add_nuclide("Zr92", 0.14759527104, 'wo')
-    top_fa.add_nuclide("Zr94", 0.15280552077, 'wo')
-    top_fa.add_nuclide("Zr96", 0.02511169542, 'wo')
+    top_fa.add_nuclide('H1', 0.0162913, 'wo')
+    top_fa.add_nuclide('O16', 0.1292776, 'wo')
+    top_fa.add_nuclide('B10', 5.25228e-5, 'wo')
+    top_fa.add_nuclide('B11', 2.39272e-4, 'wo')
+    top_fa.add_nuclide('Zr90', 0.43313403903, 'wo')
+    top_fa.add_nuclide('Zr91', 0.09549277374, 'wo')
+    top_fa.add_nuclide('Zr92', 0.14759527104, 'wo')
+    top_fa.add_nuclide('Zr94', 0.15280552077, 'wo')
+    top_fa.add_nuclide('Zr96', 0.02511169542, 'wo')
     top_fa.add_s_alpha_beta('c_H_in_H2O')
 
     bot_fa = openmc.Material(12, name='Bottom of fuel assemblies')
     bot_fa.set_density('g/cm3', 1.762)
-    bot_fa.add_nuclide("H1", 0.0292856, 'wo')
-    bot_fa.add_nuclide("O16", 0.2323919, 'wo')
-    bot_fa.add_nuclide("B10", 9.44159e-5, 'wo')
-    bot_fa.add_nuclide("B11", 4.30120e-4, 'wo')
-    bot_fa.add_nuclide("Zr90", 0.3741373658, 'wo')
-    bot_fa.add_nuclide("Zr91", 0.0824858164, 'wo')
-    bot_fa.add_nuclide("Zr92", 0.1274914944, 'wo')
-    bot_fa.add_nuclide("Zr94", 0.1319920622, 'wo')
-    bot_fa.add_nuclide("Zr96", 0.0216912612, 'wo')
+    bot_fa.add_nuclide('H1', 0.0292856, 'wo')
+    bot_fa.add_nuclide('O16', 0.2323919, 'wo')
+    bot_fa.add_nuclide('B10', 9.44159e-5, 'wo')
+    bot_fa.add_nuclide('B11', 4.30120e-4, 'wo')
+    bot_fa.add_nuclide('Zr90', 0.3741373658, 'wo')
+    bot_fa.add_nuclide('Zr91', 0.0824858164, 'wo')
+    bot_fa.add_nuclide('Zr92', 0.1274914944, 'wo')
+    bot_fa.add_nuclide('Zr94', 0.1319920622, 'wo')
+    bot_fa.add_nuclide('Zr96', 0.0216912612, 'wo')
     bot_fa.add_s_alpha_beta('c_H_in_H2O')
 
     # Define the materials file.
@@ -448,25 +448,25 @@ def pwr_assembly():
     # Define materials.
     fuel = openmc.Material(name='Fuel')
     fuel.set_density('g/cm3', 10.29769)
-    fuel.add_nuclide("U234", 4.4843e-6)
-    fuel.add_nuclide("U235", 5.5815e-4)
-    fuel.add_nuclide("U238", 2.2408e-2)
-    fuel.add_nuclide("O16", 4.5829e-2)
+    fuel.add_nuclide('U234', 4.4843e-6)
+    fuel.add_nuclide('U235', 5.5815e-4)
+    fuel.add_nuclide('U238', 2.2408e-2)
+    fuel.add_nuclide('O16', 4.5829e-2)
 
     clad = openmc.Material(name='Cladding')
     clad.set_density('g/cm3', 6.55)
-    clad.add_nuclide("Zr90", 2.1827e-2)
-    clad.add_nuclide("Zr91", 4.7600e-3)
-    clad.add_nuclide("Zr92", 7.2758e-3)
-    clad.add_nuclide("Zr94", 7.3734e-3)
-    clad.add_nuclide("Zr96", 1.1879e-3)
+    clad.add_nuclide('Zr90', 2.1827e-2)
+    clad.add_nuclide('Zr91', 4.7600e-3)
+    clad.add_nuclide('Zr92', 7.2758e-3)
+    clad.add_nuclide('Zr94', 7.3734e-3)
+    clad.add_nuclide('Zr96', 1.1879e-3)
 
     hot_water = openmc.Material(name='Hot borated water')
     hot_water.set_density('g/cm3', 0.740582)
-    hot_water.add_nuclide("H1", 4.9457e-2)
-    hot_water.add_nuclide("O16", 2.4672e-2)
-    hot_water.add_nuclide("B10", 8.0042e-6)
-    hot_water.add_nuclide("B11", 3.2218e-5)
+    hot_water.add_nuclide('H1', 4.9457e-2)
+    hot_water.add_nuclide('O16', 2.4672e-2)
+    hot_water.add_nuclide('B10', 8.0042e-6)
+    hot_water.add_nuclide('B11', 3.2218e-5)
     hot_water.add_s_alpha_beta('c_H_in_H2O')
 
     # Define the materials file.
@@ -619,7 +619,7 @@ def slab_mg(num_regions=1, mat_names=None, mgxslib_name='2g.h5'):
     # # Make Settings
     # Instantiate a Settings object, set all runtime parameters
     settings_file = openmc.Settings()
-    settings_file.energy_mode = "multi-group"
+    settings_file.energy_mode = 'multi-group'
     settings_file.tabular_legendre = {'enable': False}
     settings_file.batches = 10
     settings_file.inactive = 5
diff --git a/openmc/lattice.py b/openmc/lattice.py
index 3377e709e..71176c8ba 100644
--- a/openmc/lattice.py
+++ b/openmc/lattice.py
@@ -3,7 +3,7 @@ from collections import OrderedDict
 from collections.abc import Iterable
 from copy import deepcopy
 from math import sqrt, floor
-from numbers import Real, Integral
+from numbers import Real
 from xml.etree import ElementTree as ET
 
 import numpy as np
@@ -242,7 +242,7 @@ class Lattice(IDManagerMixin, metaclass=ABCMeta):
                         for i in range(r):
                             uarray[-1][-1].append(universe_ids[z, y, a])
                             a -= 1
-                            y +=1
+                            y += 1
 
                         # Climb up the top-left.
                         for i in range(r):
@@ -352,7 +352,7 @@ class Lattice(IDManagerMixin, metaclass=ABCMeta):
 
         unique_universes = self.get_unique_universes()
 
-        for universe_id, universe in unique_universes.items():
+        for universe in unique_universes.values():
             cells.update(universe.get_all_cells(memo))
 
         return cells
@@ -372,7 +372,7 @@ class Lattice(IDManagerMixin, metaclass=ABCMeta):
 
         # Append all Cells in each Cell in the Universe to the dictionary
         cells = self.get_all_cells(memo)
-        for cell_id, cell in cells.items():
+        for cell in cells.values():
             materials.update(cell.get_all_materials(memo))
 
         return materials
@@ -399,7 +399,7 @@ class Lattice(IDManagerMixin, metaclass=ABCMeta):
         all_universes.update(unique_universes)
 
         # Append all Universes containing each cell to the dictionary
-        for universe_id, universe in unique_universes.items():
+        for universe in unique_universes.values():
             all_universes.update(universe.get_all_universes())
 
         return all_universes
diff --git a/openmc/mgxs/mdgxs.py b/openmc/mgxs/mdgxs.py
index 2d1e75e81..75a2e6791 100644
--- a/openmc/mgxs/mdgxs.py
+++ b/openmc/mgxs/mdgxs.py
@@ -984,7 +984,7 @@ class ChiDelayed(MDGXS):
         is None unless the multi-group cross section has been computed.
     num_subdomains : int
         The number of subdomains is unity for 'material', 'cell' and 'universe'
-        domain types. When the  This is equal to the number of cell instances
+        domain types. This is equal to the number of cell instances
         for 'distribcell' domain types (it is equal to unity prior to loading
         tally data from a statepoint file).
     num_nuclides : int
@@ -1496,7 +1496,7 @@ class DelayedNuFissionXS(MDGXS):
         is None unless the multi-group cross section has been computed.
     num_subdomains : int
         The number of subdomains is unity for 'material', 'cell' and 'universe'
-        domain types. When the  This is equal to the number of cell instances
+        domain types. This is equal to the number of cell instances
         for 'distribcell' domain types (it is equal to unity prior to loading
         tally data from a statepoint file).
     num_nuclides : int
@@ -1632,7 +1632,7 @@ class Beta(MDGXS):
         is None unless the multi-group cross section has been computed.
     num_subdomains : int
         The number of subdomains is unity for 'material', 'cell' and 'universe'
-        domain types. When the  This is equal to the number of cell instances
+        domain types. This is equal to the number of cell instances
         for 'distribcell' domain types (it is equal to unity prior to loading
         tally data from a statepoint file).
     num_nuclides : int
@@ -1817,7 +1817,7 @@ class DecayRate(MDGXS):
         is None unless the multi-group cross section has been computed.
     num_subdomains : int
         The number of subdomains is unity for 'material', 'cell' and 'universe'
-        domain types. When the  This is equal to the number of cell instances
+        domain types. This is equal to the number of cell instances
         for 'distribcell' domain types (it is equal to unity prior to loading
         tally data from a statepoint file).
     num_nuclides : int
@@ -2585,7 +2585,7 @@ class DelayedNuFissionMatrixXS(MatrixMDGXS):
         is None unless the multi-group cross section has been computed.
     num_subdomains : int
         The number of subdomains is unity for 'material', 'cell' and 'universe'
-        domain types. When the  This is equal to the number of cell instances
+        domain types. This is equal to the number of cell instances
         for 'distribcell' domain types (it is equal to unity prior to loading
         tally data from a statepoint file).
     num_nuclides : int
diff --git a/openmc/plots.py b/openmc/plots.py
index 10d773868..51054549f 100644
--- a/openmc/plots.py
+++ b/openmc/plots.py
@@ -467,7 +467,7 @@ class Plot(IDManagerMixin):
         Parameters
         ----------
         geometry : openmc.Geometry
-            The geometry the base the plot off of
+            The geometry to base the plot off of
         basis : {'xy', 'xz', 'yz'}
             The basis directions for the plot
         slice_coord : float
diff --git a/openmc/plotter.py b/openmc/plotter.py
index 597a87750..af317dfdf 100644
--- a/openmc/plotter.py
+++ b/openmc/plotter.py
@@ -12,7 +12,7 @@ PLOT_TYPES = ['total', 'scatter', 'elastic', 'inelastic', 'fission',
               'absorption', 'capture', 'nu-fission', 'nu-scatter', 'unity',
               'slowing-down power', 'damage']
 
-# Supported keywoards for multi-group cross section plotting
+# Supported keywords for multi-group cross section plotting
 PLOT_TYPES_MGXS = ['total', 'absorption', 'scatter', 'fission',
                    'kappa-fission', 'nu-fission', 'prompt-nu-fission',
                    'deleyed-nu-fission', 'chi', 'chi-prompt', 'chi-delayed',
@@ -245,7 +245,7 @@ def calculate_cexs(this, data_type, types, temperature=294., sab_name=None,
     ----------
     this : {str, openmc.Nuclide, openmc.Element, openmc.Material}
         Object to source data from
-    data_type : {'nuclide', 'element', material'}
+    data_type : {'nuclide', 'element', 'material'}
         Type of object to plot
     types : Iterable of values of PLOT_TYPES
         The type of cross sections to calculate
@@ -619,7 +619,7 @@ def calculate_mgxs(this, data_type, types, orders=None, temperature=294.,
     ----------
     this : str or openmc.Material
         Object to source data from
-    data_type : {'nuclide', 'element', material', 'macroscopic'}
+    data_type : {'nuclide', 'element', 'material', 'macroscopic'}
         Type of object to plot
     types : Iterable of values of PLOT_TYPES_MGXS
         The type of cross sections to calculate
diff --git a/openmc/tallies.py b/openmc/tallies.py
index 18c359c46..3c3877e61 100644
--- a/openmc/tallies.py
+++ b/openmc/tallies.py
@@ -674,7 +674,7 @@ class Tally(IDManagerMixin):
         if equal_filters and equal_nuclides and equal_scores:
             return True
 
-        # Variables to indicate matching filter bins, nuclides and scores
+        # Variables to indicate filter bins, nuclides, and scores that can be merged
         merge_filters = self._can_merge_filters(other)
         merge_nuclides = self._can_merge_nuclides(other)
         merge_scores = self._can_merge_scores(other)
diff --git a/openmc/universe.py b/openmc/universe.py
index cbcba72c4..b64a87785 100644
--- a/openmc/universe.py
+++ b/openmc/universe.py
@@ -363,8 +363,7 @@ class Universe(IDManagerMixin):
             raise TypeError(msg)
 
         # If the Cell is in the Universe's list of Cells, delete it
-        if cell.id in self._cells:
-            del self._cells[cell.id]
+        self._cells.pop(cell.id, None)
 
     def clear_cells(self):
         """Remove all cells from the universe."""
diff --git a/scripts/casl_chain.py b/scripts/casl_chain.py
index 94fc9dd96..2edc1b6d9 100755
--- a/scripts/casl_chain.py
+++ b/scripts/casl_chain.py
@@ -3,10 +3,10 @@
 # for the VERA Depletion Benchmark Suite", CASL-U-2015-1014-000, Rev. 0,
 # ORNL/TM-2016/53, 2016.
 #
-# Note 32 of the 255 nuclides appeare twice as they are both activation
+# Note 32 of the 255 nuclides appear twice as they are both activation
 # nuclides (category 1) and fission product nuclides (category 3).
 
-# Te129 has been added due to it's link to I129 production.
+# Te129 has been added due to its link to I129 production.
 
 CASL_CHAIN = {
     # Nuclide: (Stable, CAT, IFPY, Special yield treatment)
diff --git a/scripts/openmc-ace-to-hdf5 b/scripts/openmc-ace-to-hdf5
index 1933a6e4a..9953efa8c 100755
--- a/scripts/openmc-ace-to-hdf5
+++ b/scripts/openmc-ace-to-hdf5
@@ -191,7 +191,7 @@ for filename in ace_libraries:
                     thermal = openmc.data.ThermalScattering.from_hdf5(
                                                                  nuclides[name])
                     print('Converting {} (ACE) to {} (HDF5)'
-                          .format(table.name,thermal.name))
+                          .format(table.name, thermal.name))
                     thermal.add_temperature_from_ace(table)
                     thermal.export_to_hdf5(nuclides[name] + '_1', 'w',
                                            libver=args.libver)
diff --git a/scripts/openmc-get-photon-data b/scripts/openmc-get-photon-data
index 39e44b177..84660896e 100755
--- a/scripts/openmc-get-photon-data
+++ b/scripts/openmc-get-photon-data
@@ -29,7 +29,7 @@ parser.add_argument('-c', '--cross-sections',
                     help='cross_sections.xml file to append libraries to')
 args = parser.parse_args()
 
-base_url = 'http://www.nndc.bnl.gov/endf/b7.1/zips/'
+base_url = 'https://www.nndc.bnl.gov/endf/b7.1/zips/'
 files = ['ENDF-B-VII.1-photoat.zip', 'ENDF-B-VII.1-atomic_relax.zip']
 block_size = 16384
 
@@ -63,7 +63,8 @@ for f in files:
     with open(f, 'wb') as fh:
         while True:
             chunk = req.read(block_size)
-            if not chunk: break
+            if not chunk:
+                break
             fh.write(chunk)
             downloaded += len(chunk)
             status = '{0:10}  [{1:3.2f}%]'.format(
diff --git a/scripts/openmc-make-compton b/scripts/openmc-make-compton
index c4bd5b06b..e2344e5a3 100755
--- a/scripts/openmc-make-compton
+++ b/scripts/openmc-make-compton
@@ -40,7 +40,8 @@ if download:
     with open(filename, 'wb') as fh:
         while True:
             chunk = req.read(block_size)
-            if not chunk: break
+            if not chunk:
+                break
             fh.write(chunk)
             downloaded += len(chunk)
             status = '{0:10}  [{1:3.2f}%]'.format(
diff --git a/scripts/openmc-make-depletion-chain b/scripts/openmc-make-depletion-chain
index 51092a722..01f009a2a 100755
--- a/scripts/openmc-make-depletion-chain
+++ b/scripts/openmc-make-depletion-chain
@@ -9,9 +9,9 @@ import openmc.deplete
 
 
 URLS = [
-    'http://www.nndc.bnl.gov/endf/b7.1/zips/ENDF-B-VII.1-neutrons.zip',
-    'http://www.nndc.bnl.gov/endf/b7.1/zips/ENDF-B-VII.1-decay.zip',
-    'http://www.nndc.bnl.gov/endf/b7.1/zips/ENDF-B-VII.1-nfy.zip'
+    'https://www.nndc.bnl.gov/endf/b7.1/zips/ENDF-B-VII.1-neutrons.zip',
+    'https://www.nndc.bnl.gov/endf/b7.1/zips/ENDF-B-VII.1-decay.zip',
+    'https://www.nndc.bnl.gov/endf/b7.1/zips/ENDF-B-VII.1-nfy.zip'
 ]
 
 def main():
diff --git a/scripts/openmc-make-depletion-chain-casl b/scripts/openmc-make-depletion-chain-casl
index 7fdeed072..4236916f7 100755
--- a/scripts/openmc-make-depletion-chain-casl
+++ b/scripts/openmc-make-depletion-chain-casl
@@ -24,9 +24,9 @@ from openmc._utils import download
 from casl_chain import CASL_CHAIN
 
 URLS = [
-    'http://www.nndc.bnl.gov/endf/b7.1/zips/ENDF-B-VII.1-neutrons.zip',
-    'http://www.nndc.bnl.gov/endf/b7.1/zips/ENDF-B-VII.1-decay.zip',
-    'http://www.nndc.bnl.gov/endf/b7.1/zips/ENDF-B-VII.1-nfy.zip'
+    'https://www.nndc.bnl.gov/endf/b7.1/zips/ENDF-B-VII.1-neutrons.zip',
+    'https://www.nndc.bnl.gov/endf/b7.1/zips/ENDF-B-VII.1-decay.zip',
+    'https://www.nndc.bnl.gov/endf/b7.1/zips/ENDF-B-VII.1-nfy.zip'
 ]
 
 def main():
diff --git a/scripts/openmc-make-test-data b/scripts/openmc-make-test-data
index a37a78fa9..1d376f817 100755
--- a/scripts/openmc-make-test-data
+++ b/scripts/openmc-make-test-data
@@ -18,8 +18,8 @@ import zipfile
 import openmc.data
 from openmc._utils import download
 
-base_ace = 'http://www.nndc.bnl.gov/endf/b7.1/aceFiles/'
-base_endf = 'http://www.nndc.bnl.gov/endf/b7.1/zips/'
+base_ace = 'https://www.nndc.bnl.gov/endf/b7.1/aceFiles/'
+base_endf = 'https://www.nndc.bnl.gov/endf/b7.1/zips/'
 base_wmp = 'https://github.com/mit-crpg/WMP_Library/releases/download/v1.1/'
 files = [
     (base_ace, 'ENDF-B-VII.1-neutron-293.6K.tar.gz', '9729a17eb62b75f285d8a7628ace1449'),
diff --git a/scripts/openmc-plot-mesh-tally b/scripts/openmc-plot-mesh-tally
index b4ce92587..6fa3c84f7 100755
--- a/scripts/openmc-plot-mesh-tally
+++ b/scripts/openmc-plot-mesh-tally
@@ -26,10 +26,15 @@ class MeshPlotter(tk.Frame):
     def __init__(self, parent, filename):
         tk.Frame.__init__(self, parent)
 
-        self.labels = {'Cell': 'Cell:', 'Cellborn': 'Cell born:',
-                       'Surface': 'Surface:', 'Material': 'Material:',
-                       'Universe': 'Universe:', 'Energy': 'Energy in:',
-                       'Energyout': 'Energy out:'}
+        self.labels = {
+            'Cell': 'Cell:',
+            'Cellborn': 'Cell born:',
+            'Surface': 'Surface:',
+            'Material': 'Material:',
+            'Universe': 'Universe:',
+            'Energy': 'Energy in:',
+            'Energyout': 'Energy out:'
+        }
 
         self.filterBoxes = {}
 
diff --git a/scripts/openmc-update-inputs b/scripts/openmc-update-inputs
index 3b4e9a359..c47f888c8 100755
--- a/scripts/openmc-update-inputs
+++ b/scripts/openmc-update-inputs
@@ -243,8 +243,7 @@ def update_materials(root):
     for material in root.findall('material'):
         for nuclide in material.findall('nuclide'):
             if 'name' in nuclide.attrib:
-                nucname = nuclide.attrib['name']
-                nucname = nucname.replace('-', '')
+                nucname = nuclide.attrib['name'].replace('-', '')
                 # If a nuclide name is in the ZAID notation (e.g., a number),
                 # convert it to the proper nuclide name.
                 if nucname.strip().isnumeric():
diff --git a/scripts/openmc-update-mgxs b/scripts/openmc-update-mgxs
index 8559affb9..f78a5dc69 100755
--- a/scripts/openmc-update-mgxs
+++ b/scripts/openmc-update-mgxs
@@ -44,11 +44,10 @@ def get_data(element, entry):
     value = element.find(entry)
     if value is not None:
         value = value.text.strip()
+    elif entry in element.attrib:
+        value = element.attrib[entry].strip()
     else:
-        if entry in element.attrib:
-            value = element.attrib[entry].strip()
-        else:
-            value = None
+        value = None
 
     return value
 
diff --git a/src/cross_sections.cpp b/src/cross_sections.cpp
index 6245bca9f..dca57b451 100644
--- a/src/cross_sections.cpp
+++ b/src/cross_sections.cpp
@@ -131,7 +131,7 @@ void read_cross_sections_xml()
           "materials.xml or in the OPENMC_CROSS_SECTIONS"
           " environment variable. OpenMC needs such a file to identify "
           "where to find data libraries. Please consult the"
-          " user's guide at https://openmc.readthedocs.io for "
+          " user's guide at https://docs.openmc.org/ for "
           "information on how to set up data libraries.");
       }
       settings::path_cross_sections = envvar;
diff --git a/src/distribution_energy.cpp b/src/distribution_energy.cpp
index 82754faf8..5d08cc4d2 100644
--- a/src/distribution_energy.cpp
+++ b/src/distribution_energy.cpp
@@ -191,8 +191,8 @@ double ContinuousTabular::sample(double E, uint64_t* seed) const
   double E_i1_1 = distribution_[i+1].e_out[n_discrete];
   double E_i1_K = distribution_[i+1].e_out[n_energy_out - 1];
 
-  double E_1 = E_i_1 + r*(E_i1_1 - E_i_1);
-  double E_K = E_i_K + r*(E_i1_K - E_i_K);
+  double E_1 = E_i_1 + r * (E_i1_1 - E_i_1);
+  double E_K = E_i_K + r * (E_i1_K - E_i_K);
 
   // Determine outgoing energy bin
   n_energy_out = distribution_[l].e_out.size();
@@ -317,7 +317,7 @@ double Evaporation::sample(double E, uint64_t* seed) const
     if (x <= y) break;
   }
 
-  return x*theta;
+  return x * theta;
 }
 
 //==============================================================================
diff --git a/src/geometry.cpp b/src/geometry.cpp
index 556d10650..88b48c866 100644
--- a/src/geometry.cpp
+++ b/src/geometry.cpp
@@ -492,5 +492,4 @@ extern "C" int openmc_global_bounding_box(double* llc, double* urc) {
   return 0;
 }
 
-
 } // namespace openmc
diff --git a/src/output.cpp b/src/output.cpp
index 899bce86e..a388b15d7 100644
--- a/src/output.cpp
+++ b/src/output.cpp
@@ -660,16 +660,16 @@ write_tallies()
       const auto& deriv {model::tally_derivs[tally.deriv_]};
       switch (deriv.variable) {
       case DIFF_DENSITY:
-        tallies_out << " Density derivative  Material "
+        tallies_out << " Density derivative Material "
           << std::to_string(deriv.diff_material) << "\n";
         break;
       case DIFF_NUCLIDE_DENSITY:
-        tallies_out << " Nuclide density derivative  Material "
+        tallies_out << " Nuclide density derivative Material "
           << std::to_string(deriv.diff_material) << "  Nuclide "
           << data::nuclides[deriv.diff_nuclide]->name_ << "\n";
         break;
       case DIFF_TEMPERATURE:
-        tallies_out << " Temperature derivative  Material "
+        tallies_out << " Temperature derivative Material "
           << std::to_string(deriv.diff_material) << "\n";
         break;
       default:
diff --git a/src/particle.cpp b/src/particle.cpp
index 5f6baaf57..25f595082 100644
--- a/src/particle.cpp
+++ b/src/particle.cpp
@@ -76,7 +76,7 @@ Particle::Particle()
 void
 Particle::clear()
 {
-  // reset any coordinate levels
+  // Reset any coordinate levels
   for (auto& level : coord_) level.reset();
   n_coord_ = 1;
 }
@@ -99,7 +99,7 @@ Particle::create_secondary(Direction u, double E, Type type)
 void
 Particle::from_source(const Bank* src)
 {
-  // reset some attributes
+  // Reset some attributes
   this->clear();
   alive_ = true;
   surface_ = 0;
@@ -108,7 +108,7 @@ Particle::from_source(const Bank* src)
   n_collision_ = 0;
   fission_ = false;
 
-  // copy attributes from source bank site
+  // Copy attributes from source bank site
   type_ = src->particle;
   wgt_ = src->wgt;
   wgt_last_ = src->wgt;
@@ -183,7 +183,7 @@ Particle::transport()
         return;
       }
 
-      // set birth cell attribute
+      // Set birth cell attribute
       if (cell_born_ == C_NONE) cell_born_ = coord_[n_coord_ - 1].cell;
     }
 
diff --git a/src/tallies/derivative.cpp b/src/tallies/derivative.cpp
index 290d09384..f6f10cf7a 100644
--- a/src/tallies/derivative.cpp
+++ b/src/tallies/derivative.cpp
@@ -617,6 +617,7 @@ void score_collision_derivative(const Particle* p)
 {
   // A void material cannot be perturbed so it will not affect flux derivatives.
   if (p->material_ == MATERIAL_VOID) return;
+
   const Material& material {*model::materials[p->material_]};
 
   for (auto& deriv : model::tally_derivs) {
diff --git a/src/tallies/filter_cell.cpp b/src/tallies/filter_cell.cpp
index 7cc007756..9e08c0c21 100644
--- a/src/tallies/filter_cell.cpp
+++ b/src/tallies/filter_cell.cpp
@@ -12,7 +12,7 @@ namespace openmc {
 void
 CellFilter::from_xml(pugi::xml_node node)
 {
-  // Get cell IDs and convert into indices into the global cells vector
+  // Get cell IDs and convert to indices into the global cells vector
   auto cells = get_node_array<int32_t>(node, "bins");
   for (auto& c : cells) {
     auto search = model::cell_map.find(c);
diff --git a/src/tallies/tally_scoring.cpp b/src/tallies/tally_scoring.cpp
index 7ca279966..51eae2620 100644
--- a/src/tallies/tally_scoring.cpp
+++ b/src/tallies/tally_scoring.cpp
@@ -248,12 +248,15 @@ double get_nuclide_neutron_heating(const Particle* p, const Nuclide& nuc,
 {
   size_t mt = nuc.reaction_index_[rxn_index];
   if (mt == C_NONE) return 0.0;
+
   auto i_temp = p->neutron_xs_[i_nuclide].index_temp;
   if (i_temp < 0) return 0.0; // Can be true due to multipole
+
   const auto& rxn {*nuc.reactions_[mt]};
   const auto& xs {rxn.xs_[i_temp]};
   auto i_grid = p->neutron_xs_[i_nuclide].index_grid;
   if (i_grid < xs.threshold) return 0.0;
+
   auto f = p->neutron_xs_[i_nuclide].interp_factor;
   return (1.0 - f) * xs.value[i_grid-xs.threshold]
     + f * xs.value[i_grid-xs.threshold+1];
@@ -1316,7 +1319,7 @@ score_general_ce(Particle* p, int i_tally, int start_index,
       }
     }
 
-    // Add derivative information on score for differnetial tallies.
+    // Add derivative information on score for differential tallies.
     if (tally.deriv_ != C_NONE)
       apply_derivative_to_score(p, i_tally, i_nuclide, atom_density, score_bin,
         score);
diff --git a/tools/ci/travis-install.py b/tools/ci/travis-install.py
index 9a9b06dae..a2b1b6175 100644
--- a/tools/ci/travis-install.py
+++ b/tools/ci/travis-install.py
@@ -63,7 +63,6 @@ def main():
     omp = (os.environ.get('OMP') == 'y')
     mpi = (os.environ.get('MPI') == 'y')
     phdf5 = (os.environ.get('PHDF5') == 'y')
-
     dagmc = (os.environ.get('DAGMC') == 'y')
 
     # Build and install