radioactivedecay 0.3.3

A Python package for radioactive decay modelling that supports 1252 radionuclides, decay chains, branching, and metastable states.

radioactivedecay is a Python package for radioactive decay calculations. It supports decay chains of radionuclides, metastable states and branching decays. By default it uses the decay data from ICRP Publication 107, which contains 1252 radionuclides of 97 elements.

It solves the radioactive decay differential equations analytically using NumPy and SciPy linear algebra routines. There is also a high numerical precision decay mode using SymPy routines, useful for when there are orders of magnitude differences between half-lives of radionuclides in the same decay chain.

• Full Documentation: https://alexmalins.com/radioactivedecay

Installation

radioactivedecay requires Python 3.6+. Install radioactivedecay from the Python Package Index using pip:

$ pip install radioactivedecay

This command will also install the dependencies (Matplotlib, NetworkX, NumPy, SciPy & SymPy) if they are not already present in the environment.

Usage

Decay calculations

Create an Inventory of radionuclides and decay it as follows:

>>> import radioactivedecay as rd
>>> inv_t0 = rd.Inventory({'Mo-99': 2.0})
>>> inv_t1 = inv_t0.decay(20.0, 'h')
>>> inv_t1.contents
{'Mo-99': 1.6207863893776937,
'Tc-99': 9.05304236308454e-09,
'Tc-99m': 1.3719829376710406}

An Inventory of 2.0 Bq of Mo-99 was decayed for 20 hours, producing the radioactive progeny Tc-99m and Tc-99.

Note we did not have to specify the units of the initial Mo-99 activity. This is because the output activity units are the same as the input units. So the above calculation could have represented the decay of 2.0 Ci of Mo-99, or of 2.0 dpm, 2.0 kBq, etc.

We supplied 'h' as an argument to decay() to specify the decay time period had units of hours. Supported time units include 'μs', 'ms', 's', 'm', 'h', 'd', 'y' etc. Note seconds ('s') is the default if no unit is supplied to decay().

Radionuclides can be specified in three equivalent ways in radioactivedecay. The strings

• 'Rn-222', 'Rn222' or '222Rn',
• 'Ir-192n', 'Ir192n' or '192nIr'

are all equivalent ways of specifying ²²²Rn or ¹⁹²ⁿIr.

Plotting decay graphs

Use the plot() method to graph of the decay of an Inventory over time:

>>> inv_t0.plot(20, 'd')

The graph shows the decay of Mo-99 over 20 days, leading to the ingrowth of Tc-99m and a trace quantity of Tc-99. Graphs are drawn using Matplotlib.

Fetching decay data

The Radionuclide class can be used to fetch decay information for individual radionuclides, e.g. for Rn-222:

>>> nuc = rd.Radionuclide('Rn-222')
>>> nuc.half_life('d')
3.8235
>>> nuc.progeny()
['Po-218']
>>> nuc.branching_fractions()
[1.0]
>>> nuc.decay_modes()
['α']

Likewise similar methods exist for Inventory instances:

>>> inv_t1.half_lives('readable')
{'Mo-99': '65.94 h', 'Tc-99': '0.2111 My', 'Tc-99m': '6.015 h'}
>>> inv_t1.progeny()
{'Mo-99': ['Tc-99m', 'Tc-99'], 'Tc-99': ['Ru-99'], 'Tc-99m': ['Tc-99', 'Ru-99']}
>>> inv_t1.branching_fractions()
{'Mo-99': [0.8773, 0.1227], 'Tc-99': [1.0], 'Tc-99m': [0.99996, 3.7e-05]}
>>> inv_t1.decay_modes()
{'Mo-99': ['β-', 'β-'], 'Tc-99': ['β-'], 'Tc-99m': ['IT', 'β-']}

Decay chain diagrams

The Radionuclide class includes a plot() method for drawing decay chain diagrams:

>>> nuc = rd.Radionuclide('Mo-99')
>>> nuc.plot()

These diagrams are drawn using NetworkX and Matplotlib.

High numerical precision decay calculations

radioactivedecay includes a high numerical precision decay mode. This can give more reliable results for decay chains containing both long- and short-lived radionuclides:

>>> inv_t0 = rd.Inventory({'U-238': 1.0})
>>> inv_t1 = inv_t0.decay_high_precision(10.0, 'd')
>>> inv_t1.contents
{'At-218': 1.4511675857141352e-25,
'Bi-210': 1.8093327888942224e-26,
'Bi-214': 7.09819414496093e-22,
'Hg-206': 1.9873081129046843e-33,
'Pa-234': 0.00038581180879502017,
'Pa-234m': 0.24992285949158477,
'Pb-210': 1.0508864357335218e-25,
'Pb-214': 7.163682655782086e-22,
'Po-210': 1.171277829871092e-28,
'Po-214': 7.096704966148592e-22,
'Po-218': 7.255923469955255e-22,
'Ra-226': 2.6127168262000313e-21,
'Rn-218': 1.4511671865210924e-28,
'Rn-222': 7.266530698712501e-22,
'Th-230': 8.690585458641225e-16,
'Th-234': 0.2499481473619856,
'Tl-206': 2.579902288672889e-32,
'Tl-210': 1.4897029111914831e-25,
'U-234': 1.0119788393651999e-08,
'U-238': 0.9999999999957525}

How radioactivedecay works

radioactivedecay calculates an analytical solution to the radioactive decay differential equations using linear algebra operations. It implements the method described in this paper: M Amaku, PR Pascholati & VR Vanin, Comp. Phys. Comm. 181, 21-23 (2010). See the theory docpage for more details.

It uses NumPy and SciPy routines for standard decay calculations (double-precision floating-point operations), and SymPy for arbitrary numerical precision calculations.

By default radioactivedecay uses decay data from ICRP Publication 107 (2008).

The notebooks folder in the GitHub repository contains Jupyter Notebooks for creating the decay datasets that are read in by radioactivedecay, e.g. ICRP 107. It also contains some comparisons against decay calculations made with PyNE and Radiological Toolbox.

Tests

From the base directory run:

$ python -m unittest discover

License

radioactivedecay is open source software released under the MIT License. The ICRP-107 decay data is copyright 2008 A. Endo and K.F. Eckerman. See LICENSE for details.

Contributing

Contributors are welcome to fix bugs, add new features or make feature requests. Please open a pull request or a new issue on the GitHub repository.