Desorption of plutonium from montmorillonite: An experimental and modeling study

Plutonium Desorption from Nuclear Melt Glass-Derived Colloids and Implications for Migration at the Nevada National Security Site, USA

“…151 Similar to the studies of Tinnacher et al 32 and Begg et al 28 Effluent reservoirs were replaced twice per day and weighed. In total, 9 effluent samples were collected for each experiment.…”

“…Results 28 show that Pu associated with clay colloids will migrate on the timescale of years to tens of years but not centuries, before Pu will completely desorb. However, the model 28 In this study, we advance the work of Zavarin et al 21 to explore the desorption rates of Pu and Cs from the 1000-days, hydrothermally produced nuclear melt glass colloids. Flow cell For comparison to the nuclear melt glass-derived colloids, a third system was studied using 238 Pu that had been previously sorbed for ~8 months to a montmorillonite colloid suspension of purified SWy-1 (referred to as SWy) and prepared as described in the SI.…”

“…31 A second Pu(IV) sorbed species, Pu(IV) S3 , was considered in 209 the model to account for aging processes other than redox reactions. 28 Model equations, 210 model input parameters, and a schematic overview of the reactions included in the model are 211 described in detail in the SI.…”

Derivation of a speciic activity limit for plutonium for near surface disposal a case study at a potential site in northwest China

“…Although a spe cific ac tiv ity limit can be de rived by divid ing the in ven tory through ground wa ter ex po sure by the waste vol ume in the dis posal fa cil ity, the derived limit could be 2 to 3 or ders of mag ni tude greater than that ob tained for hu man in tru sion ex po sure pathways [31]. Ba si cally, Pu moves slowly down wards in the soil, into the ground wa ter due to its strong af fin ities for sol ids and lim ited mo bil ity un der nat u ral condi tions, re gard less of the mech a nisms of its trans port, e. g., colloid forms, mi cro bial ac tiv ity and desorption, which may en hance or in hibit the mo bil ity of Pu in the subsurface de pend ing on its com plex speciation and ad di tional hydrogeological char ac ter is tics [19,21,29,[35][36][37][38]. That is, com pared to ground wa ter mi gra tion and well-wa ter drink ing, hu man in tru sion cases, which are min i mally site-de pend ent and of gen eral use, may pres ent a re stricted con di tion in the der i vation of lim its of radionuclides.…”

“…To date, is sues con cern ing with the plu to nium iso topes ac cu mu la tion in near sur face en vi ron ment, e. g., its long-term stor age and dis posal, have been dis cussed and an a lyzed ex ten sively. These in clude re views of the en vi ron men tal trans port of pluto nium [12,13], eval u a tions of global fall out from atmo spheric nu clear weap ons tests of the 1950s and 1960s [14][15][16], anal y ses of plu to nium iso topes in the air [17,18], and ex per i men tal and mod el ling stud ies of trans port mech a nisms [19][20][21][22]. Nev er the less, re ports on ap proaches to es tab lish ing ac tiv ity lim its for transuranic nuclides, i. e., 239 Pu, as well as their il lus trations, are lack ing, par tic u larly in China, where lim ited gen eral re search on the con cept of in ter me di ate depth dis posal for ra dio ac tive waste is avail able [23].…”