# Radionuclides

THYRSIS takes into account radioactive decay and specific activity of radionuclides. Radioactive decay is used in radionuclide transport simulations and specific activity is used for concentration to activity conversion.

These values are read from the elements_chimiques table, which can be filled by using the following command :

    python -m thyrsis.database.load_chemicals radionuclides.csv

The `radionuclides.csv` file is provided in the `thyrsis/tutorial_data` directory. It is a csv file with `;` separator and the following sorted columns:

- `name`

- `period`

- `atomic_mass`

- `radioactive_decay`

- `specific_activity`

- `water_quality_limit`

- `atomic_number`

- `masse_number`