When the only natural isotope francium-223 is specifically required, it is produced as the alpha daughter of actinium-227, itself produced synthetically from the neutron irradiation of natural radium-226, one of the daughters of natural uranium-238.
wˌɛn ðɪ ˈoʊnli nˈætʃɚɹəl ˈaɪsətˌoʊp fɹˈænsiəm tˈuːhˈʌndɹɪd twˈɛnti θɹˈiː ɪz spəsˈɪfɪkli ɹᵻkwˈaɪɚd, ɪɾ ɪz pɹədˈuːst æz ðɪ ˈælfə dˈɔːɾɚɹ ʌv æktˈɪniəm tˈuːhˈʌndɹɪd twˈɛnti sˈɛvən, ɪtsˈɛlf pɹədˈuːst sɪnθˈɛɾɪkli fɹʌmðə nˈuːtɹɑːn ˌɪɹeɪdɪˈeɪʃən ʌv nˈætʃɚɹəl ɹˈeɪdiəm tˈuːhˈʌndɹɪd twˈɛnti sˈɪks, wˈʌn ʌvðə dˈɔːɾɚz ʌv nˈætʃɚɹəl jʊɹɹˈeɪniəm tˈuːhˈʌndɹɪd θˈɜːɾi ˈeɪt.