Bitumen was used starting in the 1960s as a hydrophobic matrix aiming to encapsulate radioactive waste such as medium-activity salts (mainly soluble sodium nitrate and sodium sulfate) produced by the reprocessing of spent nuclear fuels or radioactive sludges from sedimentation ponds.
bɪtˈuːmɛn wʌz jˈuːzd stˈɑːɹɾɪŋ ɪnðə nˈaɪntiːnhˈʌndɹɪd sˈɪksti z æz ɐ hˌaɪdɹəfˈoʊbɪk mˈeɪtɹɪks ˈeɪmɪŋ tʊ ɛŋkˈæpsjʊlˌeɪt ɹˌeɪdɪoʊˈæktɪv wˈeɪst sˈʌtʃ ɐz mˈiːdiəmæktˈɪvᵻɾi sˈɔlts mˈeɪnli sˈɑːljuːbəl sˈoʊdiəm nˈaɪtɹeɪt ænd sˈoʊdiəm sˈʌlfeɪt pɹədˈuːst baɪ ðə ɹᵻpɹˈɑːsɛsɪŋ ʌv spˈɛnt nˈuːklɪɹ fjˈuːəlz ɔːɹ ɹˌeɪdɪoʊˈæktɪv slˈʌdʒᵻz fɹʌm sˌɛdɪməntˈeɪʃən pˈɑːndz.