Re-evaluation of the use of low activation materials in waste management strategies for fusion

Petti, David A.; McCarthy, K.A.; Taylor, Neill; Forty, C.B.A.; Forrest, R.A.

doi:10.1016/s0920-3796(00)00229-5

Cited by 23 publications

(10 citation statements)

References 6 publications

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“…The proposed limits for fusion systems are 10 Sv/h for hands on operation, and 10 mSv/h for remote handling [30]. For this study, the hands on limit was disregarded since the coolant after shutdown could be drained down into cooling tanks.…”

Section: Contact Dose Ratementioning

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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Section: Contact Dose Ratementioning

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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“…Analysis has shown that, for low power density machines, a combined strategy of specific LAM usage and shielding allows the outboard fusion vacuum vessel and all magnets to be cleared or recycled, and also that adequate shielding allows the activated material that cannot be cleared to be disposed of as low level waste. 42 By contrast, for compact machines, with high power density and high neutron wall loading, the overall volume of activated material is much smaller than in low power density machines. However, although all components can be classified as low level waste, neither the in-vessel components nor the magnets can be cleared even after an extended storage time of 100 years.…”

Section: Recent Sande Evaluations and Findingsmentioning

confidence: 99%

“…It is not clear that the public understands or appreciates the differences between low level waste that meets 10CFR61.55 Class C requirements versus high level waste that exceeds these requirements. 42,53 As a result, the choice between generation of small quantities of high-level waste versus large quantities of low-level waste is a difficult one worthy of community discussion and debate. This discussion must occur in the context of overall machine design optimization strategies, physics and technology design assumptions, and the evolving political climate surrounding waste disposal.…”

Section: Future Directionsmentioning

confidence: 99%

Status of Safety and Environmental Activities in the U.S. Fusion Program

Petti

Reyes

Cadwallader

et al. 2005

Fusion Science and Technology

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“…Concerns about the environment, radwaste burden for future generations, lack of geological repositories, and high disposal cost directed our attention to recycling of the AM (for reuse within the nuclear industry) and clearance (the unconditional release to the commercial market or disposal in a non-nuclear landfill). In fact, the recycling and clearance options have been investigated by fusion researchers in the late 1980s and 1990s, focusing on selected materials or components [1][2][3], then examining almost all fusion components in the late 1990s and 2000s [4][5][6][7]. Recycling and clearance became more technically feasible with the development of advanced radiation-resistant remote handling (RH) tools that can recycle highly irradiated materials [8,9] and with the introduction of the clearance category for slightly radioactive materials by national and international nuclear agencies [10,11].…”

Section: Introductionmentioning

confidence: 99%