Recent advances in the treatment of irradiated graphite: A review

Li, Junfeng; Dunzik-Gouga, Mary Lou; Wang, Jianlong

doi:10.1016/j.anucene.2017.06.040

Cited by 24 publications

(6 citation statements)

References 27 publications

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“…Moreover, for those i-graphite stocks that have experienced just a very low activation during reactor operation, like in nuclear research reactors, these outcomes may be exploited to demonstrate the applicability of surface decontamination processes with the purpose to declassify most of the waste inventory. [20,30] This decontamination practice would result in the loosening of regulatory control on a material otherwise considered a radioactive waste. Hence, both management costs and environmental footprint would be reduced, since a smaller amount of material would have to be disposed as a radioactive waste.…”

Section: Resultsmentioning

confidence: 99%

“…[13,18,19] Nitrogen is present as an impurity coming both from graphite manufacturing process and reactor operating environment. [20] This concurrent activation path could explain 14 C distribution with depth, as the external graphite layers should be more enriched in 14 N than the bulk due to manufacturing process and exposure to air,. [13,17,21] Dealing with 36 Cl, a depth gradient may similarly arise from activation of 35 Cl by (n,γ) reaction, since 35 Cl may be more concentrated in the superficial layers of the graphite blocks as well.…”

Section: Introductionmentioning

confidence: 99%

“…[22] In this case, the purification treatments usually performed during graphitization involve the exposure of carbon blocks to halogen gases, such as fluorinated and chlorinated gases. [20] Chlorine diffuses through the porous structure to react with the metallic impurities and forms halides of low boiling point that vaporize from the block: as graphitization process takes places, some gas molecules may remain trapped in the pores of the material, thus originating a depth profile for 35 Cl, which, upon activation, generates 36 Cl. [23] Hence, one of the most ambitious goals of this work is demonstrating the existence of depth distribution profiles of 14 N and 35 Cl.…”

Section: Introductionmentioning

confidence: 99%

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Determination of nuclear graphite impurities by prompt gamma activation analysis to support decommissioning operations

Mossini

Révay

Camerini

et al. 2022

J Radioanal Nucl Chem

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Elemental composition of non-irradiated nuclear grade graphite was determined by Prompt Gamma Activation Analysis (PGAA) to quantitively assess some neutron activation precursors. The knowledge of these data is paramount for an accurate radiological characterization of the material before decommissioning of graphite-moderated nuclear reactors. Bulk results of most of the nuclides were consistent with benchmark Inductively Coupled Plasma–Mass Spectrometry (ICP-MS) and literature data. In the case of 14N and 35Cl, depth distribution profiles were observed and quantified for the first time. These outcomes could shine a light on 14C and 36Cl depth distribution profiles and fractional release during leaching experiments.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Determination of nuclear graphite impurities by prompt gamma activation analysis to support decommissioning operations

Mossini

Révay

Camerini

et al. 2022

J Radioanal Nucl Chem

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“…The ORIGEN cross sections of the FFTF and PWRUE cores were used in irradiation calculations for Natrium and the reference PWR, respectively. An activated graphite block contains C-14, H-3, Cl-36, and Co-60 (Li 2017). Except for C-14, the activities of these isotopes are much lower than the GTCC criteria.…”

Section: A-2 Decommissioning Volume Of Gtcc Llwmentioning

confidence: 97%

Nuclear Waste Attributes of SMRs Scheduled for Near-Term Deployment

Kim

Boing

Halsey

et al. 2022

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The purpose of this study is to evaluate the nuclear waste attributes of Small Modular Reactors (SMRs) scheduled for deployment within this decade using available data and established nuclear waste metrics, with the results compared to a reference large Pressurized Water Reactor (PWR).The current fleet of commercial nuclear reactors in the U.S. is composed of 92 large Light Water Reactors (LWR) with an average electricity generating capacity of over 1,000 MWe each. These large LWRs built on-site in massive construction projects have been the mainstay of the industry for the last 50 years. However, new construction soon is expected to include several designs of smaller reactors primarily fabricated in factories and installed in the field in modules. Some of these SMRs will also be LWRs, while some will use other coolants such as liquid metals, molten salts or gases, and different types of fuels. The technologies and economics of SMRs have been the focus of many studies, but there has been only minimal information published on the amount of nuclear waste different types of SMRs are expected to generate and no reports focused on near-term-deployable designs.In this study, the nuclear waste attributes of three small reactors scheduled for near-term-deployment, VOYGR TM (from NuScale Power), Natrium TM ab (from TerraPower), and Xe-100 (from X-energy), were assessed by comparing nuclear waste metrics with those of a reference large Pressurized Water Reactor (PWR). These reactors were selected for this study for several reasons:  First, they represent a range of reactor and fuel technologies, allowing comparison of the waste performance of these different technologies. VOYGR TM is a PWR design using the same type of ceramic fuel as found in larger LWRs, Natrium is liquid metal cooled and uses a metal alloy fuel, and Xe-100 is a helium cooled reactor using pebbles containing TRi-structural ISOtropic (TRISO) particle fuel. Collectively, these three technologies cover a range of proposed SMRs. Second, they represent comparatively mature designs that have been selected for DOE support for near-term deployment and have some expectation of commercial viability. Each design has been developed to improve performance, providing for a meaningful comparison versus existing commercial reactors. Third, they are all active designs deployable in the near-term. Sites for first units of each design have been announced, licensing activities are underway, and all three are scheduled to be operational by the end of the decade. An understanding of the waste attributes of these designs is needed to inform on any significant differences that may impact future nuclear waste management.a) Public information indicates "<5%", so conservatively used 4.95% Front-end wastes are represented by the depleted uranium (DU) mass generated during the uranium enrichment process. All designs use the same once-through fuel cycle as current LWRs, and the DU generated has no useful application in any current once-through cycle e . However, DU would be an as...

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“…In spite of the need raised by hydrogen storage, the knowledge of the adsorption and desorption behavior of hydrogen isotopes in graphite is also required when dealing with irradiated nuclear graphite. Nuclear graphite has been widely used in various reactors, and there are over 250,000 tons of irradiated nuclear graphite awaiting processing . Despite the accumulation of irradiated nuclear graphite resulting from the operation of existing or decommissioned reactors, graphite will also be used in generation IV nuclear reactors. , In irradiated nuclear graphite, tritium is the radionuclide with the highest content and contributes most of the radioactivity in the first few years .…”

Section: Introductionmentioning

confidence: 99%

Adsorption and Desorption of Tritium on/from Nuclear Graphite

et al. 2021

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The interaction between graphene-based materials and hydrogen isotopes is of great importance with respect to the adsorption of hydrogen in graphene and the removal of tritium from irradiated nuclear graphite. In the present study, based on density functional theory, we investigate and discuss the adsorption and molecular desorption of hydrogen isotopes on the edges and stable interior defects. The adsorption energy of one hydrogen on graphene-based materials is between −2.0 and −5.0 eV, which is related to the structure and hydrogenation level. The hydrogenation level increases with the hydrogen partial pressure and decreases with the temperature. The best adsorption pathways of hydrogen isotopes in graphene-based materials are determined, together with three different desorption stages with different activation energies. The desorption peaks of thermal desorption spectrometry agree well with stage 2 and stage 3 of simulation. Our results can provide a theoretical basis for the study of the hydrogen isotope behaviors in graphene and the decontamination of nuclear graphite.

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Recent advances in the treatment of irradiated graphite: A review

Cited by 24 publications

References 27 publications

Determination of nuclear graphite impurities by prompt gamma activation analysis to support decommissioning operations

Determination of nuclear graphite impurities by prompt gamma activation analysis to support decommissioning operations

Nuclear Waste Attributes of SMRs Scheduled for Near-Term Deployment

Adsorption and Desorption of Tritium on/from Nuclear Graphite

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