Feasibility studies of DEMO potential waste recycling by proven existing industrial-scale processes

Pace, L. Di; Beone, Teresa; Donato, Antonello Di; Miceli, Patrizia; Macci, F.; Piancaldini, Roberto; Zanin, Egidio

doi:10.1016/j.fusengdes.2018.11.047

Cited by 5 publications

(17 citation statements)

References 2 publications

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“…Many of the long-lived radionuclides are produced in tiny concentrations and relatively minor changes to existing near-surface repository designs may allow these to be accepted at higher levels; (iv) the problematic long-lived radionuclides could be extracted via processing before waste material (steel) is released for long-term storage. For example, recent and ongoing work within the European DEMO design programme suggests that it could be possible to decarburize both SS316 and Eurofer using oxygen to levels below one part per million (ppm) [30]. Under such circumstances the equivalent reduction in 14 C (a small fraction of carbon but it would be reduced by the same relative amount) would decrease its corresponding Becquerel activity far below the UK-LLW limit.…”

Section: Discussionmentioning

confidence: 99%

Waste implications from minor impurities in European DEMO materials

et al. 2019

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Waste-production predictions for the future demonstration fusion power plant (DEMO) are necessary to produce an accurate picture of the likely environmental and economic costs of radioactive waste disposal at end-of-life. An integrated simulation process combining Monte-Carlo neutron transport simulations, inventory calculations, and extensive and reproducible post-processing algorithms has been used for the evolving European DEMO designs to quantify the time-varying mass inventories in different waste classes for individual regions and components of the reactor vessel, as well as for the reactor as a whole. Waste categories based on UK and French regulations reveal that minor impurities contained in structural steels, particularly Eurofer, as well as in functional materials such as tungsten, and beryllium, can have a significant impact on their waste classification prospects. Predictions for current European DEMO concepts suggest that there may be an issue in disposing of fusion structural-steel waste as low-level waste (LLW) in near-surface repositories. Detailed analysis of the subtleties of these predictions, particularly with regard to the production of long-lived radionuclides such as 14C and 94Nb, reveal that the threshold for acceptance as LLW is only just exceeded in some situations. Several mitigation approaches are discussed in this context. The computational framework developed for these assessments can be rapidly and continuously applied to the maturing DEMO design, helping to guide design choices to mitigate long-lived waste production and ensure that most waste becomes LLW or better within a few decades.

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Section: Discussionmentioning

confidence: 99%

Waste implications from minor impurities in European DEMO materials

et al. 2019

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“…The key factors that determine how RW should be disposed of have been extensively discussed in [13,14]. The national regulations implemented by the relevant waste management organisations include the operational limits of particular interim storage facilities and the acceptance criteria at the chosen disposal sites [11,15,16].…”

Section: Current Llw and Ilw Repositoriesmentioning

confidence: 99%

“…Previous studies [1][2][3] of waste expectations of fusion have identified that activity from 3 H, 63 Ni, 94 Nb and 14 C can pose significant challenge to achieving LLW classification. The presence of 99 Tc can also be a problem in some steels due to its long half life.…”

Section: Limits Of Interest To Fusionmentioning

confidence: 99%

Waste expectations of fusion steels under current waste repository criteria

2021

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During operation fusion reactor components will be exposed to long periods of neutron irradiation. As such, a reactor’s structural steels will become activated and need to be disposed of as radioactive waste. Previous studies have shown that such wastes can struggle to meet low level waste (LLW) requirements meaning that costly geological disposal may be required. In order to explore the waste expectations of steels from European DEMO-like fusion reactors, several radioactive waste management systems have been investigated. This includes their LLW criteria, currently available disposal sites and planned future developments. This information was used to analyse the results of DEMO-like inventory simulations of potential reactor steels. The simulations were performed with the inventory code FISPACT-II and the TENDL2017 nuclear data library. The results suggest that when steels are exposed to near plasma neutron fluxes they will struggle to meet the majority of LLW requirements. For lower neutron fluxes, typical of reactor containment vessels, the waste expectations can be more positive, with several steels able to meet some low level criteria. It can be concluded that steels should not be expected to be consistently internationally classified as LLW 100 years after reactor shut down. As all activated fusion waste cannot be disposed of in a single location, it is recommended that waste disposal strategies are included in any fusion reactor proposal before construction begins. These strategies need to align with the radioactive waste regulations the proposed reactor will be subject to.

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“…Literature data from previous fundamental analysis have been used to define the process parameters both for decarburization (ref. [1]) and to produce powders for the preparation of AM samples (ref. [2]).…”

Section: Introductionmentioning

confidence: 99%

“…The thermodynamic analysis (ref. [3]) showed that in a decarburization process of EUROFER steel, at temperature of 1700 °C and pressure of 1 mbar absolute, a minimum value of 1.15 ppm of carbon concentration, starting from an initial value of 1200 ppm [1], can be obtained without oxidation of other steel components. The minimum C concentration without slag, at 1700 °C and 1 mbar, in the decarburization of AISI 316L is 5.2 ppm.…”

Section: Introductionmentioning

confidence: 99%