A novel method to stably secure beryllium resources for fusion blankets

doi:10.1016/j.jnucmat.2020.152522

Journal of Nuclear Materials

Volume 542, 15 December 2020, 152522

https://doi.org/10.1016/j.jnucmat.2020.152522 Get rights and content

Highlights

•
A huge amount of beryllium (Be), with a weight of approximately 490 tons, is necessary for DEMO.
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To provide a steady supply of Be for DEMO, Be mine development is necessary, including the installation of new refinement facilities.
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Beryllium ores were completely dissolved by base and acid solution treatment with microwave heating.
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A novel refinement process for creating Be metal from Be ores has been successfully established.

Abstract

A demonstration (DEMO) fusion reactor will require a huge amount of beryllium (Be) with approximately 490 tons. Since the total production of Be in the world, for now, is approximately 300 tons per year, it is anticipated that the demand is dramatically increased as the early realization of the fusion reactor proceeds. The presence of many Be mines, as well as information on each Be reserve, has already been confirmed with surveys. Since a conventional Be refinement process is considerably complicated including a production process for an intermediate product, Be(OH)₂, high-temperature treatments, and handling of toxic powdery states, however, Be raw materials are costly. To provide a steady supply of Be for DEMO, in parallel with the development of mines, a novel Be refinement technique using an economical and safe process is imperative. According to these requirements, a novel and advanced refinement process of Be metal from ores was suggested by applying microwave melting at low temperatures through wet processing.

It was obvious as a result of dissolubility tests that bertrandite and beryl ores were completely dissolved by using a process with acid solutions and microwave heating after treatment with base solutions and microwave heating. Further, the process can be utilized to produce not only intermediate products, such as beryllium hydroxide (Be(OH)₂) and beryllium oxide (BeO) but also pure beryllium metal. Moreover, this process has great advantages for extracting uranium which is one of critical issues and oxide impurities for reuse.

Introduction

Beryllium (Be), in terms of its applications, has been used in fields with specific environmental conditions, the aerospace and aircraft industries, X-ray window materials, and refractors in nuclear reactors. Among its many applications, Be use is allocated to beryllium copper (BeCu) alloys, which have excellent strength [1]. As a raw material of this alloy, beryllium hydroxide, Be(OH)₂ has been using and accounted for 90 % of the total production of beryllium [2].

And, Be is one of the most important elements in mineral resources for fusion blankets and is also one of 30 rare metal elements. Although its use is crucial to the blanket design of the demonstration (DEMO) fusion reactor, it is known that more than 490 tons of Be is necessary for one reactor [3]. Effective resource procurement should therefore be established to stably secure Be resources and ensure the early realization of fusion reactors. According to a survey on the current state of mineral resources, Be production districts are concentrated in relatively limited areas of the world [4]. The concentration of these production districts does not relate to the number of Be reserves. Confirmation of the presence of many Be mines as well as information on each Be reserve has already been gathered using surveys [5]. The only countries known to process beryllium ores and refine to beryllium materials are the Unites States, Kazakhstan, and China [2]. These manufacturers adopted the dry process for the refinement from beryllium ores through beryllium hydroxide, Be(OH)₂, which converts into diverse materials, such as metal, BeCu alloy, and oxide. It is no wonder that it is costly since the conventional refinement process focusing on Be(OH)₂ production, is complicated with dry process and includes high-temperature process and handling with toxic powdery states. Therefore, to create a steady supply of Be, not only Be mine development but also a novel Be refinement process with an economical and safe process should be essentially developed.

In this study, the current state of Be refinement techniques is first described by adding demand and supply for materials in the fusion reactor. Furthermore, a novel method for Be refinement is suggested and then its prospect is outlined.

Section snippets

Experiments

We first surveyed Be ores and resources and evaluated the necessary quantity of resources by considering the total amount of each material as well as its annual production. In contrast to the conventional Be ore refinement method, a new microwave process is then suggested, and its effect on dissolution is demonstrated both in the case of base and acid treatment and treatment with acid alone.

Dissolubility tests were performed using a base and acid solution with and without microwave heating. The

Be resources for DEMO

Be metal and its alloys are candidate materials for neutron multipliers, as indicated in Fig. 1. It has been reported [3] that the DEMO reactors require a large amount of Be, approximately 490 tons for one reactor per every four years. The total Be resources in the world are currently estimated to weight approximately 0.5 million tons [5] while the worldwide annual production amount is about 300 tons [2]. Since the worldwide refinement facilities in operation are only a few and Be is costly

Conclusions

To create a steady supply of Be for DEMO, Be mine development, including the installation of a new refinement facility, is necessary. In parallel with mine development, the development of a novel Be refinement method using economical and safe processes is also essential.

Given this context, a novel Be refinement process using Be ores was suggested according to low-temperature treatment and wet processes. The proposed method does not create any intermediate products, such as Be(OH)₂ or BeO, and

Declaration of Competing Interest

None.

Acknowledgements

We would like to thank R. Hiwatari (QST, Japan) for sharing the information and N. Fuji (Japan Mining Engineering and Training Center, Japan) for assistance with survey for beryllium resource.

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Beryllium is one of the breeding functional materials for fusion applications, and beryllium is refined from beryl (Be₃Al₂Si₆O₁₈), which is difficult to dissolve. The new innovative process replaces the conventional energy-intensive steps in the purification process from beryl with a low-temperature treatment by reaction under a basic aqueous solution. The process can significantly contribute to energy saving in the refinement process. In this study, we investigated the kinetics of the reaction of beryl with aqueous NaOH solution under microwave heating, proving that a mixed kinetic model well explained the reaction based on a process that proceeds by instantaneous surface nucleation and a diffusion-controlled process. The apparent activation energies for the leaching of Be, Al, and Si in beryl were estimated to be 67–72 kJ/mol. The reaction of beryl with NaOH solution was suggested that Al and Si dissolved at low temperatures react with Na in the solution to form zeolitic fabriesite at temperatures above 200 °C.
Strengthening/embrittlement effects induced by segregation of transmutation He and Li at Be {101̄1} grain boundary by first-principles calculations
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First-principles calculations have been performed to investigate the effect of segregation of transmutation helium and lithium atoms on the strength of beryllium {10 $\bar{1}$ 1} grain boundary. For the stability of transmutation lithium and helium atoms in bulk beryllium, both of them preferentially occupy the substitutional site with the lowest formation energy. In the investigation of segregation behavior of multiple transmutation lithium and helium atoms at the grain boundary, it has been found that more helium atoms tend to segregate at the {10 $\bar{1}$ 1} grain boundary compared with the limited segregation of lithium atoms. Meanwhile, the equilibrium concentration of both helium and lithium atoms decreases with the rising of temperature. The segregation of one lithium atom could improve the stability of grain boundary, while the stability of grain boundary could be degraded due to the segregation of more lithium and helium atoms. In addition, the segregation of lithium and helium atoms has different effects on the strength of grain boundary. On the one hand, the transmutation lithium atoms exert a strengthening effect on the strength of grain boundary, which could be beneficial for the improvement of properties of beryllium grain boundary. On the other hand, the segregation of transmutation helium atoms could impose an embrittlement effect which reduces the strength of grain boundary. Besides, it has also been verified that the co-segregation of transmutation lithium and helium atoms weakens the stability and strength of {10 $\bar{1}$ 1} grain boundary. Moreover, the influence of helium atoms on the stability and strength of grain boundary is more obvious than that of lithium atoms. The theoretical work will hopefully provide some insights into the segregation behavior of transmutation atoms at the grain boundary of beryllium, which could be significant for the improvement of strength of grain boundary of beryllium by the grain boundary segregation engineering.
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Dissolution and recovery of beryllium from beryl using a novel wet process with microwave heating
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Citation Excerpt :
This conventional refining process consumes a large amount of energy through the use of high temperatures, hence requiring the use of high-grade beryl and leading to a major environmental problem. In contrast, our new wet process has the potential to significantly reduce economic and environmental problems by using microwaves at lower temperatures [10]. In addition, when considering beryllium for fusion reactors, the concentration of uranium in beryllium is extremely important.
Because a large amount of beryllium is loaded into fusion reactors as a neutron multiplier, it is important to stably secure the beryllium resource, i.e., beryl ore (Be₃Al₂Si₆O₁₈), in order to realize fusion energy. The conventional method for extracting beryllium from beryl involves high-temperature processing steps, which may increase the cost and environmental risk. In view of this, a new wet process using microwaves at significantly lower temperatures was proposed. This study investigated the factors that enable the new wet process to achieve lower temperatures compared to the conventional method, and confirmed through tests that a chemical reaction occurs between beryl and NaOH at approximately 200 °C during the pretreatment process. It was found that this chemical reaction plays an important role in reducing the temperature of the process. The separation tests were performed to separate Al and Si from beryl minerals using this wet process, and the optimum conditions for each separation process were determined. Beryllium oxide and beryllium hydroxide were successfully recovered from the solution after Al and Si separation.
Evaluation of several conditioning matrices for the management of radioactive metal beryllium wastes
2022, Journal of Nuclear Materials
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It is also under study as interesting material for the future fusion power reactors. In the International Thermonuclear Experimental Reactor, Be constitutes the main plasma facing for the first wall of the tokamak and the neutron multiplier in the breeding blanket [6–10]. The use of beryllium in fission and fusion reactors will make it radioactive by neutron irradiation.
Beryllium wastes are produced by nuclear industry. One way to manage them is their encapsulation in cements. The main risk of this conditioning is the aqueous corrosion, which leads to the hydrogen production and cracks causing a loss of radioactivity confinement. The corrosion can be limited by the formation of the hydroxide solid phase Be(OH)_2(s). The stability domain of this phase was calculated in water as a function of the pH: M. Pourbaix has calculated a stability domain from 2.9 to 11.7 for a 10⁻⁴ M beryllium concentration, while according to our calculation with more recent thermodynamic data, it is stable from 5.3 to 13.5. Based on Pourbaix results, beryllium cannot be conditioned in the mainly used cement for nuclear waste, Portland cement, while it is possible according to our calculations. Experimental measurements were achieved to select the data set most in agreement with the experimental observations. The beryllium reactivity has been examined in matrices having different pH pore solution: brushite cement (pH 1.75–6.44), magnesium phosphate cement (pH 5.6–8.4), calcium-sulfoaluminate cement (pH 10.9–12.3), Portland cement (pH 12.5–12.9) cements and activated slag (pH 12.9–13.8), by measuring the open circuit potential and by electrochemical impedance spectroscopy. The experimental results agree with the more recent thermodynamic data. Beryllium corrosion is too high in the brushite cement, leading to a high hydrogen production. This matrix can then not be envisaged for the conditioning of Be waste. If the beryllium is encapsulated in the activated slag, the highly alkalinity is too high in the early age, leading to a high aqueous corrosion. Activated slag are also not suitable for Be conditioning. The main conclusion of this paper is that beryllium can be encapsulated in safe conditions in Portland, magnesium phosphate and calcium sulfoaluminate cements.

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A novel method to stably secure beryllium resources for fusion blankets

Highlights

Abstract

Introduction

Section snippets

Experiments

Be resources for DEMO

Conclusions

Declaration of Competing Interest

Acknowledgements

Fusion Eng. Des.

Hydrometallurgy

Miner. Eng.

J. Nucl. Mater.

Miner. Eng.

J Nucl. Mater.

Mater. Today Proc.

Production of Cu-Be master from beryllium oxide

Miner. Process. Extr. Metall. Rev.