Sorption of Plutonium and Americium on Repository, Backfill and Geological Materials Relevant to The JNFL Low-Level Radioactive Waste Repository at Rokkasho-Mura

Baston, G. Μ. N.; Berry, Jessica; Brownsword, M.; Heath, Timothy G.; Tweed, C.J.

doi:10.1557/proc-353-957

Cited by 9 publications

(10 citation statements)

References 4 publications

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“…Dario et al (2006) studied the interaction of Eu(III) with Portland cement: sorption was strong (R d = 4610 6 l kg À1 , I = 0.3, pH = 12.3À12.7, 1 g l À1 ). Baston et al (1995) measured Am(III) uptake on concrete (R d = 1.3610 5 l kg À1 , pH = 12.4, 20 g l À1 ) and mortar (R d = 4.5610 4 l kg, pH = 12.2, 20 g l À1 ). Tits et al (2003) studied C-S-H Eu sorption across the range [Eu] = 10 À10 À7610 À7 M. Sorption was strong and rapid, with an R d of 6610 5 l kg À1 (0.5 g l À1 ).…”

Section: Discussionmentioning

confidence: 99%

“…The NRVB is quite different to the C-S-H and cement samples that have been studied previously, but the pH values recorded here are in the same region as for previous studies. For example, Dario et al (2006) report cement solution pH in the range 12.3À12.7 (I = 0.3; 0.001 g ml À1 ), whereas Baston et al (1995) measured pH 12.4 for concrete and 12.2 for mortar at 0.02 g ml À1 , and Pointeau et al (2008) measured pH 13.2 for fresh cement at 0.940 g ml À1 . As the real pH for the data in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Dario et al, 2006), concretes (e.g. Baston et al, 1995), calcium silicate hydrates (C-S-H) (e.g. Pointeau et al, 2001) and calcite (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Europium interaction with a vault backfill at high pH

Telchadder¹,

Smith²,

Bryan³

2012

Mineral. mag.

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Batch experiments have been used to assess the sorption properties of a potential cementitious repository backfill, NRVB (Nirex reference vault backfill), using Eu 3+ as a model trivalent radionuclide and ethylenediaminetetraacetic acid (EDTA) as a competing ligand. The NRVB is an effective scavenger of Eu from solution, with most sorbed within minutes onto the crushed material and less than 1.5% remaining in solution after one day (R d values in the range 0.3À2.4610 4 l kg À1 ). Ultrafiltration showed that nearly all of this remaining Eu (>94%) is attached to NRVB derived colloids or particulates that are mainly retained by a 100 kDa ultrafilter. High concentrations of EDTA (>0.01 M) reduced the extent of sorption at apparent equilibrium. The addition of EDTA to a pre-equilibrated system of Eu 3+ and NRVB resulted in a temporary suspension of some Eu, but this very quickly returned to the solid phase. There is some irreversibility in these systems, with EDTA able to prevent removal of Eu(III) from solution, but unable to bring it back into solution under the same conditions.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Europium interaction with a vault backfill at high pH

Telchadder¹,

Smith²,

Bryan³

2012

Mineral. mag.

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“…Solubility and sorption of plutonium in cementitious environments have been addressed in various experimental and modelling studies suggesting a strong sorption of plutonium to the cement matrix and a rather low solubility of about 5610 À11 mol l À1 at pH 12.5 (e.g. Baston et al, 1995;Berner, 2002). We are not aware that any systematic investigations on the dissolution kinetics of calcined PuO 2 in a cementitious repository are available, although it might be inferred to be lower than for UO 2 under comparable conditions.…”

Section: Cementitious Wasteformsmentioning

confidence: 99%

Durability of potential plutonium wasteforms under repository conditions

et al. 2012

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Separated stocks of UK civil plutonium are currently held as a zero value asset in storage, as there is no final decision about whether they should be treated as a resource for future use as nuclear fuel or as waste. Irrespective of future UK government strategies regarding plutonium, at least a portion of the UK civil plutonium inventory will be designated for geological disposal. In this context, we performed a high-level review of the performance of potential wasteforms for the disposal of separated civil plutonium. The key issues considered were the durability and chemical reactivity of the wasteforms in aqueous environments and the long-term radionuclide release under conditions relevant to geological disposal. The major findings of the review, relevant not only to the situation in the UK but to plutonium disposal in general, are summarized in this paper. The review showed that, in the event of a decision being taken to declare plutonium as a waste for disposal, more systematic studies would be required to constrain the wasteform performance under repository conditions in order to derive realistic source terms for a safety case.

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“…Burial in deep geologic repositories is one strategy that has been investigated with the idea that waste packages would be isolated with natural and engineered barriers to prevent leakage until the radioactivity has largely decayed. Although laboratory experiments Huber et al, 2011;Sch€ afer et al, 2012) and field studies Kersting et al, 1999;Kurosawa et al, 2006;M€ ori et al, 2003;Wang et al, 2014bWang et al, , 2013a have been conducted to evaluate radionuclide colloid-facilitated transport, uncertainty remains regarding the potential transport of strongly sorbing radionuclides associated with mobile colloidal particles (Baston et al, 1994;Dittrich and Reimus, 2014;Dittrich, 2012;Sch€ afer and Noseck, 2010;Wold, 2010). Reliable data concerning americium (Am) transport in association with bentonite colloids through geochemically altered granite materials is relatively sparse and is the focus of this paper.…”

Section: Introductionmentioning

confidence: 99%

Laboratory investigation of the role of desorption kinetics on americium transport associated with bentonite colloids

Dittrich

Boukhalfa

Ware

et al. 2015

Journal of Environmental Radioactivity

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Understanding the parameters that control colloid-mediated transport of radionuclides is important for the safe disposal of used nuclear fuel. We report an experimental and reactive transport modeling examination of americium transport in a groundwater-bentonite-fracture fill material system. A series of batch sorption and column transport experiments were conducted to determine the role of desorption kinetics from bentonite colloids in the transport of americium through fracture materials. We used fracture fill material from a shear zone in altered granodiorite collected from the Grimsel Test Site (GTS) in Switzerland and colloidal suspensions generated from FEBEX bentonite, a potential repository backfill material. The colloidal suspension (100 mg L(-1)) was prepared in synthetic groundwater that matched the natural water chemistry at GTS and was spiked with 5.5 × 10(-10) M (241)Am. Batch characterizations indicated that 97% of the americium in the stock suspension was adsorbed to the colloids. Breakthrough experiments conducted by injecting the americium colloidal suspension through three identical columns in series, each with mean residence times of 6 h, show that more than 95% of the bentonite colloids were transported through each of the columns, with modeled colloid filtration rates (k(f)) of 0.01-0.02 h(-1). Am recoveries in each column were 55-60%, and Am desorption rate constants from the colloids, determined from 1-D transport modeling, were 0.96, 0.98, and 0.91 h(-1) in the three columns, respectively. The consistency in Am recoveries and desorption rate constants in each column indicates that the Am was not associated with binding sites of widely-varying strengths on the colloids, as one binding site with fast kinetics represented the system accurately for all three sequential columns. Our data suggest that colloid-mediated transport of Am in a bentonite-fracture fill material system is unlikely to result in transport over long distance scales because of the ability of the fracture materials to rapidly strip Am from the bentonite colloids and the apparent lack of a strong binding site that would keep a fraction of the Am strongly-associated with the colloids.

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Sorption of Plutonium and Americium on Repository, Backfill and Geological Materials Relevant to The JNFL Low-Level Radioactive Waste Repository at Rokkasho-Mura

Cited by 9 publications

References 4 publications

Europium interaction with a vault backfill at high pH

Europium interaction with a vault backfill at high pH

Durability of potential plutonium wasteforms under repository conditions

Laboratory investigation of the role of desorption kinetics on americium transport associated with bentonite colloids

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