Initial Integration of Accident Safety, Waste Management, Recycling, Effluent, and Maintenance Considerations for Low-Activation Materials

Piet, Steven J.; Cheng, E.T.; Fetter, Steve; Herring, J.S.

doi:10.13182/fst19-1-146

Cited by 42 publications

(7 citation statements)

References 12 publications

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“…Whilst these element are relatively passive in the long-term, some remain highly active in the short-term, in particular Mn. Such elements may present problems for maintenance operations, and their decay heat may be a considerable concern in loss-of-coolant accidents [ 25 , 26 ]. Nevertheless, there is also the possibility (even if it remains far-fetched) that this short-term decay heat be utilised positively, for example, for smoothing pulsed-operation power cycles, or for in-situ annealing of damage.…”

Section: Desired Properties and Element Restrictionsmentioning

confidence: 99%

High-Entropy Alloys for Advanced Nuclear Applications

Pickering

Carruthers

Barron

et al. 2021

Entropy

198

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The expanded compositional freedom afforded by high-entropy alloys (HEAs) represents a unique opportunity for the design of alloys for advanced nuclear applications, in particular for applications where current engineering alloys fall short. This review assesses the work done to date in the field of HEAs for nuclear applications, provides critical insight into the conclusions drawn, and highlights possibilities and challenges for future study. It is found that our understanding of the irradiation responses of HEAs remains in its infancy, and much work is needed in order for our knowledge of any single HEA system to match our understanding of conventional alloys such as austenitic steels. A number of studies have suggested that HEAs possess ‘special’ irradiation damage resistance, although some of the proposed mechanisms, such as those based on sluggish diffusion and lattice distortion, remain somewhat unconvincing (certainly in terms of being universally applicable to all HEAs). Nevertheless, there may be some mechanisms and effects that are uniquely different in HEAs when compared to more conventional alloys, such as the effect that their poor thermal conductivities have on the displacement cascade. Furthermore, the opportunity to tune the compositions of HEAs over a large range to optimise particular irradiation responses could be very powerful, even if the design process remains challenging.

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Section: Desired Properties and Element Restrictionsmentioning

confidence: 99%

High-Entropy Alloys for Advanced Nuclear Applications

Pickering

Carruthers

Barron

et al. 2021

Entropy

198

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“…The assumptions made in the various investigations di er, but the general conclusions are quite consistent. Piet et al [5] evaluated all elements of the periodic table (through Bi) with respect to safety, waste disposal (using existing United States regulations), and the potential for recycle. Con®rming the initial conclusions, vanadium alloys and ferritic/martensitic steels were identi®ed as possible low activation structural alloys and graphite and silicon carbide as possible low activation structural ceramics.…”

Section: Low Activation ± Rationale For Structural Materials Optionsmentioning

confidence: 99%

The challenge of developing structural materials for fusion power systems

Bloom¹

1998

Journal of Nuclear Materials

199

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Nuclear fusion can be one of the most attractive sources of energy from the viewpoint of safety and minimal environmental impact. Central in the goal of designing a safe, environmentally benign, and economically competitive fusion power system is the requirement for high performance, low activation materials. The general performance requirements for such materials have been de®ned and it is clear that materials developed for other applications (e.g. aerospace, nuclear ®ssion, fossil energy systems) will not fully meet the needs of fusion. Advanced materials, with composition and microstructure tailored to yield properties that will satisfy the speci®c requirements of fusion must be developed. The international fusion programs have made signi®cant progress towards this goal. Compositional requirements for low activation lead to a focus of development e orts on silicon carbide composites, vanadium alloys, and advanced martensitic steels as candidate structural material systems. Control of impurities will be critically important in actually achieving low activation but this appears possible. Neutron irradiation produces signi®cant changes in the mechanical and physical properties of each of these material systems raising feasibility questions and design limitations. A focus of the research and development e ort is to understand these e ects, and through the development of speci®c compositions and microstructures, produce materials with improved and adequate performance. Other areas of research that are synergistic with the development of radiation resistant materials include fabrication, joining technology, chemical compatibility with coolants and tritium breeders and speci®c questions relating to the unique characteristics of a given material (e.g. coatings to reduce gas permeation in SiC composites) or design concept (e.g. electrical insulator coatings for liquid metal concepts). Ó

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“…The waste disposal rating (WDR) determines whether the alloy meets the concentration limits for Class C low-level waste (LLW) under NRC 10CFR61.55 [31]. It is defined as the sum of the ratio of the concentration of a particular isotope to the maximum allowed concentration of that isotope for Class C, taken over all isotopes of the alloy.…”

Section: Waste Disposal Ratingmentioning

confidence: 99%

Neutronics and activation analysis of lithium-based ternary alloys in IFE blankets

Jolodosky

Kramer

Meier

et al. 2016

Fusion Engineering and Design

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h i g h l i g h t s • Monte Carlo calculations were performed on numerous lithium ternary alloys. • Elements with high neutron multiplication performed well with low absorbers. • Enriching lithium decreases minimum lithium concentration of alloys by 60% or more. • Alloys that performed well neutronically were selected for activation calculations. • Alloys activated, except LiBaBi, do not pose major environmental or safety concerns. a b s t r a c t An attractive feature of using liquid lithium as the breeder and coolant in fusion blankets is that it has very high tritium solubility and results in very low levels of tritium permeation throughout the facility infrastructure. However, lithium metal vigorously reacts with air and water and presents plant safety concerns. The Lawrence Livermore National Laboratory is carrying an effort to develop a lithium-based ternary alloy that maintains the beneficial properties of lithium (e.g. high tritium breeding and solubility) and at the same time reduces overall flammability concerns. This study evaluates the neutronics performance of lithium-based alloys in the blanket of an inertial fusion energy chamber in order to inform such development. 3-D Monte Carlo calculations were performed to evaluate two main neutronics performance parameters for the blanket: tritium breeding ratio (TBR), and the fusion energy multiplication factor (EMF). It was found that elements that exhibit low absorption cross sections and higher q-values such as Pb, Sn, and Sr, perform well with those that have high neutron multiplication such as Pb and Bi. These elements meet TBR constrains ranging from 1.02 to 1.1. However, most alloys do not reach EMFs greater than 1.15. Additionally, it was found that enriching lithium with 6 Li significantly increases the TBR and decreases the minimum lithium concentration by more than 60%. The amount of enrichment depends on how much total lithium is in the alloy to begin with. Alloys that performed well in the TBR and EMF calculations were considered for activation analysis. Activation simulations were executed with 50 years of irradiation and 300 years of cooling. It was discovered that bismuth is a poor choice due to achieving the highest decay heat, contact dose rates, and accident doses. In addition, it does not meet the waste disposal ratings (WDR). Some of the activation results for alloys with Sn, Zn, and Ga were in the higher end and should be considered secondary to elements such as Sr and Ba that had overall better results. The results of this study along with other considerations such as thermodynamics, and chemical reactivity will help down select a preferred lithium ternary alloy.

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Initial Integration of Accident Safety, Waste Management, Recycling, Effluent, and Maintenance Considerations for Low-Activation Materials

Cited by 42 publications

References 12 publications

High-Entropy Alloys for Advanced Nuclear Applications

High-Entropy Alloys for Advanced Nuclear Applications

The challenge of developing structural materials for fusion power systems

Neutronics and activation analysis of lithium-based ternary alloys in IFE blankets

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