radioactivedecay 0.0.4

A Python package for radioactive decay calculations that supports 1252 radionuclides, including full decay chains and branching.

radioactivedecay

radioactivedecay is a Python package for performing radioactive decay calculations. It supports 1252 radionuclides, including full decay chains and branching.

Installation

radioactivedecay requires Python 3.6+, NumPy and SciPy.

The easiest way to install radioactivedecay is via the Python Package index using pip:

$ pip install radioactivedecay

Usage

Example 1

radioactivedecay is based around inventories of radionuclides, which are created as follows:

>>> import radioactivedecay as rd
>>> tritium_initial = rd.Inventory({'H-3': 10.0})
>>> tritium_initial.contents
{'H-3': 10.0}

Here an inventory of 10 Bq of H-3 (tritium) was initialized by supplying a dictionary to Inventory(). Radionuclides can be specified in three equivalent ways:

• e.g. 'Rn-222', 'Rn222' or '222Rn',
• or 'Ir-192n', 'Ir192n' or '192nIr' (for second metastable state of Ir-192).

Calculate the radioactive decay of an inventory by:

>>> tritium_decayed = tritium_initial.decay(12.32, 'y')
>>> tritium_decayed.contents
{'H-3': 5.0}

In this example the 10 Bq of H-3 was decayed for one half-life (12.32y), yielding 5 Bq of H-3. Note the decay() function takes two arguments: the decay time and its units ('s', 'm', 'h', 'd' or 'y').

Example 2

Inventories can contain more than one radionuclide. In this example the inventory initially contains Tc-99m and I-123. Decaying it demonstrates the ingrowth of radioactive progeny via decay chains. The decay period is 20 hours.

>>> mix = rd.Inventory({'Tc-99m': 2.3, 'I-123': 5.8})
>>> mix.decay(20.0, 'h').contents
{'I-123': 2.040459244534774,
 'Tc-99': 6.729939210983381e-09,
 'Tc-99m': 0.22950748010063513,
 'Te-123': 9.4851587443927e-18,
 'Te-123m': 7.721174031572363e-07}

Tc-99 is the progeny of Tc-99m, and Te-123 and Te-123m are progeny of I-123.

Example 3

radioactivedecay includes a Radionuclide class. It can be used to fetch the half-lives of radionuclides:

>>> rd.Radionuclide('Rn-222').halflife('d')
3.8235
>>> rd.Radionuclide('C-14').halflife('y')
5700.0

The half-lives of Rn-222 and C-14 are 3.8235 days and 5700 years, respectively.

How it works

radioactivedecay uses decay data from ICRP Publication 107 (2008). https://journals.sagepub.com/doi/pdf/10.1177/ANIB_38_3

It calculates an analytical solution to the decay chain differential equations using matrix algebra. Refer to the following paper for more details on the method: M Amaku, PR Pascholati & VR Vanin, Comp. Phys. Comm. 181, 21-23 (2010) https://doi.org/10.1088/0952-4746/26/3/N02

It uses NumPy and SciPy for matrix operations.

Limitations

The following processes are not modelled by radioactivedecay

• ingrowth of progeny from spontaneous fission decays
• neutronics, i.e. no modelling of induced radioactivity or fission
• external sources inputting radioactivity into the system

Care is needed when decaying backwards in time (i.e. supplying a negative time to the decay() function), as this can result in numerical instabilities and nonsense results.

Acknowledgements

Special thanks to assistance from

• Center for Computational Science & e-Systems, Japan Atomic Energy Agency
• Kenny McKee