[PDF]    http://dx.doi.org/10.3952/physics.v55i1.3058

Open access article / Atviros prieigos straipsnis

Lith. J. Phys. 55, 54–62 (2015)
IMMOBILIZATION OF RADIOACTIVE WASTE IN CEMENT: IODINE BINDING BY CEMENTITIOUS MATERIALS UNDER HIGHLY ALKALINE CONDITIONS
Rūta Druteikienė, Justina Šapolaitė, Žilvinas Ežerinskis, Evaldas Naujalis, and Andrius Puzas
Center for Physical Sciences and Technology, Savanorių Ave. 231, LT-02300 Vilnius, Lithuania
E-mail: ruta@ar.fi.lt

Received 8 October 2014; revised 4 December 2014; accepted 20 March 2015

This work is directed to assess iodine interactions with hardened cement paste (HCP) under highly alkaline conditions (pH > 12) with/without a reductant. For this purpose, a series of Kd (distribution coefficient) experiments using 127I as a tracer were performed. The Kd values of iodine were in the order of 172–1095 mL g–1 in the batch experiment without a reductant, and in the order of 83–92 mL g–1 in the experiment with a reductant. The percentage of iodine leached out from HCP throughout the experiment suggested its very strong binding with cementitious materials. The obtained results allow supposing that chemical speciation of iodine has influence on the interaction of iodine with HCP under highly alkaline conditions.
Keywords: iodine, cement, sorption, desorption, Kd
PACS: 28.41.Kw, 68.43.Mn, 68.43.-h, 82.80.Bg, 07.75.th

RADIOAKTYVIŲJŲ ATLIEKŲ KIETINIMAS CEMENTU: JODO JUNGTIS SU BETONU STIPRIAI ŠARMINĖJE APLINKOJE
Rūta Druteikienė, Justina Šapolaitė, Žilvinas Ežerinskis, Evaldas Naujalis, Andrius Puzas
Valstybinis mokslinių tyrimų institutas Fizinių ir technologijos mokslų centras, Vilnius, Lietuva

Radioaktyviųjų atliekų saugyklų inžinerinių barjerų funkcija – užtikrinti ilgalaikį ir saugų pavojingų atliekų laikymą užkertant kelią nekontroliuojamam radionuklidų sklidimui į aplinką. Potencialus radionuklidų sklidimas per saugyklų inžinerinius barjerus gali atsirasti dėl oksiduojančio / redukuojančio aplinkos poveikio ir dėl to susidarančių radioaktyviųjų elementų cheminių savybių pokyčių. Radioaktyviųjų elementų sulaikymas kietinančioje matricoje yra svarbi sąlyga, leidžianti užtikrinti efektyvų radioaktyviųjų atliekų saugojimą.
Darbe buvo tiriama jodo (127I) sorbcijos į hidratuotą cementą ir išplovimo iš jo kinetika, proceso priklausomybė nuo elemento cheminės formos stipriai šarminėje (pH > 12) terpėje naudojant / nenaudojant reduktorių Na2S2O4. Nustatytas jodo pasiskirstymo tarp kietos ir skystos fazės koeficientas (Kd). Eksperimentinėje sistemoje be reduktoriaus jodo Kd kito 172–1095 mL g–1 ribose, sistemoje su reduktoriumi jodido (I–) Kd siekė 83–92 mL g–1.
Eksperimento rezultatai rodo, kad stipriai šarminėje aplinkoje jodas yra efektyviai fiksuojamas cemento matricoje ir jo sorbcija priklauso nuo jodo oksidacijos laipsnio.
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