Iodine immobilization: Development of solidification process for spent silver-sorbent using hot isostatic press technique

Masuda, Kaoru; Katoh, Osamu; Tanaka, Yoshiaki; Nakajima, Shinichi; Okamoto, Shinya; Sakuragi, Tomofumi; Yoshida, Satoshi

doi:10.1016/j.pnucene.2015.09.012

Cited by 5 publications

(7 citation statements)

References 13 publications

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“…This suggests that the silver was impregnated heterogeneously in the original AgA, and that the iodine adsorbed onto the silver to form compounds, such as AgI and AgIO 3 . The presence of AgI and AgIO 3 was confirmed through X-ray diffraction (XRD) analysis of 100%-loaded AgA ( Masuda et al, 2016 ).…”

Section: Resultsmentioning

confidence: 98%

“…Two materials were uniformly mixed in an equivalent weight ratio and the mixture was encapsulated in a stainless steel can (50 cm 3 ) and heated at 450°C under high vacuum (<133 × 10 −5 Pa) for 2 h to remove volatile components. This thermal treatment before HIP allows all iodine species to change to silver iodide (AgI) and the solid to become denser ( Masuda et al, 2016 ). The HIP treatment was then performed at 1,325°C and 175 MPa for 3 h using an Ar gas-pressurized HIP system (Kobelco, Dr. HIP).…”

Section: Methodsmentioning

confidence: 99%

“…Hot isostatic pressing (HIP) is a promising consolidation treatment for iodine immobilization to produce durable iodine-bearing waste ( Fujihara et al, 1999 ; Vance et al, 2005 ; Sakuragi et al, 2015 ; Masuda et al, 2016 ; Matyas et al, 2016 ; Maddrell et al, 2019 ). Direct consolidation of spent AgA is advantageous, as it is a simple process that does not generate secondary waste.…”

Section: Introductionmentioning

confidence: 99%

“…However, little to no information was found on the actual iodine load fraction ( f load ) relevant to the DOG system of the Rokkasho reprocessing facility. In previous studies, several simulated waste forms were synthesized using AgA with an iodine loading of 100% ( Sakuragi et al, 2015 ; Masuda et al, 2016 ).…”

Section: Introductionmentioning

confidence: 99%

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Characteristics of iodine-bearing silver-impregnated alumina sorbents and their direct solidification via hot isostatic pressing

Sakuragi¹,

Yoshida

Katoh

2023

Front. Chem.

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Waste management for radioiodine is a key issue for the sustainable nuclear fuel cycle. The iodine adsorption behavior on a bed column of a silver-impregnated alumina sorbent (AgA) under conditions designed to match those of the Rokkasho reprocessing facility dissolver off-gas (DOG) system was investigated using different volatilized iodine concentrations. Cross-sectional observations of iodine-bearing AgA grains revealed that iodine was adsorbed as silver iodide and silver iodate, and gradually distributed from the surface to the inside of the AgA. The iodine distribution throughout the AgA beds allowed us to estimate the length of the mass-transfer zone. This suggests that the iodine load fraction in AgA (adsorbed iodine/total impregnated silver) will be averaged to 50% in the expected facility equipment design. This study also describes the waste form durability after disposal. To reproduce the average iodine loading in the waste form, 100%-loaded AgA grains were mixed with an equal amount of commercially available alumina reagents and consolidated through hot isostatic pressing at 175 MPa and 1,325°C for 3 h. The resultant 50%-loaded solid was used for the static leaching test over 4.5 years, where the leached iodine was less than 0.2% under simple reducing conditions. This suggested that the HIPed solid of AgA from Rokkasho DOG showed preferable water resistance for after disposal safety.

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Section: Resultsmentioning

confidence: 98%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characteristics of iodine-bearing silver-impregnated alumina sorbents and their direct solidification via hot isostatic pressing

Sakuragi¹,

Yoshida

Katoh

2023

Front. Chem.

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“…The investigation of AgI-containing alumina wasteforms has been well established with the use of HIP with these wasteforms being previously demonstrated (Tanabe et al, 2010). More recently, further work looking at the effect of pre-treatment of the material prior to HIP has been reported (Masuda et al, 2016). In the study, an alumina material containing 10 mass% silver was loaded with iodine and consolidated by HIP, resulting in an iodine loading of 10.2 mass%.…”

Section: Alumina Based Wasteformsmentioning

confidence: 98%

Review of recent developments in iodine wasteform production

et al. 2022

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Radioiodine capture and immobilization is not only important to consider during the operation of reactors (i.e., I-131), during nuclear accidents (i.e., I-131 and I-129) or nuclear fuel reprocessing (i.e., I-131 and I-129), but also during disposal of nuclear wastes (i.e., I-129). Most disposal plans for I-129-containing waste forms (including spent nuclear fuel) propose to store them in underground repositories. Here, iodine can be highly mobile and, given its radiotoxicity, needs to be carefully managed to minimize long-term environmental impacts arising from disposal. Typically, any process that has been used to capture iodine from reprocessing or in a reactor is not suitable for direct disposal, rather conversion into a wasteform for disposal is required. The objectives of these materials are to use either chemical immobilization or physical encapsulation to reduce the leaching of iodine by groundwaters. Some of the more recent ideas have been to design capture materials that better align with disposal concepts, making the industrial processing requirements easier. Research on iodine capture materials and wasteforms has been extensive. This review will act as both an update on the state of the research since the last time it was comprehensively summarized, and an evaluation of the industrial techniques required to create the proposed iodine wasteforms in terms of resulting material chemistry and applicability.

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Solid sorbents for gaseous iodine capture and their conversion into stable waste forms

Pénélope

Campayo

Fournier

et al. 2022

Journal of Nuclear Materials

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Iodine immobilization: Development of solidification process for spent silver-sorbent using hot isostatic press technique

Cited by 5 publications

References 13 publications

Characteristics of iodine-bearing silver-impregnated alumina sorbents and their direct solidification via hot isostatic pressing

Characteristics of iodine-bearing silver-impregnated alumina sorbents and their direct solidification via hot isostatic pressing

Review of recent developments in iodine wasteform production

Solid sorbents for gaseous iodine capture and their conversion into stable waste forms

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