add amount of tritium to TBR task

[shimwell]

this question always comes up so i think we should add this calculation to the end of the tbr task

fusion_power = 1e9  # in units of watts so this is 1GW 
energy_of_each_fusion_reaction = 17.5e6 * 1.60218e-19  # eV converted to Joules
DT_neutrons_per_second = fusion_power / energy_of_each_fusion_reaction
mass_of_tritium_in_grams = 3.01604928 * 1.66054e-24  # this is 3 atomic mass units converted to grams with 1/  Avogadro constant
tritium_mass_used_per_day_in_grams = mass_of_tritium_in_grams * 60 * 60 *24 * DT_neutrons_per_second  # assuming all fusion energy comes from DT reactions, ignore small amount of DD reactions
print(int(tritium_mass_used_per_day_in_grams))