Hydrides as neutron moderator and reflector materials

Vetrano, J. S.

doi:10.1016/0029-5493(70)90159-7

Cited by 62 publications

(38 citation statements)

References 51 publications

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“…The bulk density of YH 2 is smaller than that of ZrH 2 and the dissociation temperature of YH 2 is 1200 °C, which is 300 °C higher than that of ZrH 2 . These physical and chemical properties may help to avoid thermal spikes 42 , 43 . Furthermore, we have revealed that the thermal spike observed for ZrH 2 can be suppressed by using the deuteride (ZrD 2 ) instead of the hydride 44 .…”

Section: Introductionmentioning

confidence: 99%

Method to Reduce Long-lived Fission Products by Nuclear Transmutations with Fast Spectrum Reactors

Chiba

Wakabayashi

Tachi

et al. 2017

Sci Rep

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Transmutation of long-lived fission products (LLFPs: 79Se, 93Zr, 99Tc, 107Pd, 129I, and 135Cs) into short-lived or non-radioactive nuclides by fast neutron spectrum reactors without isotope separation has been proposed as a solution to the problem of radioactive wastes disposal. Despite investigation of many methods, such transmutation remains technologically difficult. To establish an effective and efficient transmutation system, we propose a novel neutron moderator material, yttrium deuteride (YD2), to soften the neutron spectrum leaking from the reactor core. Neutron energy spectra and effective half-lives of LLFPs, transmutation rates, and support ratios were evaluated with the continuous-energy Monte Carlo code MVP-II/MVP-BURN and the JENDL–4.0 cross section library. With the YD2 moderator in the radial blanket and shield regions, effective half-lives drastically decreased from 106 to 102 years and the support ratios reached 1.0 for all six LLFPs. This successful development and implementation of a transmutation system for LLFPs without isotope separation contributes to a the ability of fast spectrum reactors to reduce radioactive waste by consuming their own LLFPs.

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Section: Introductionmentioning

confidence: 99%

Method to Reduce Long-lived Fission Products by Nuclear Transmutations with Fast Spectrum Reactors

Chiba

Wakabayashi

Tachi

et al. 2017

Sci Rep

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“…If a reasonably low partial pressure (~1 atm) is needed, either calcium hydride (liquid phase or liquid-solid mixture) [17], yttrium hydride (solid phase) [18], or some lanthanide hydrides can be adopted (see Figure 1 , which summarizes data in Ref. [1]). If higher hydrogen partial pressure in the moderator enclosure is acceptable, zirconium and titanium hydrides may also be used.…”

Section: Literature Review On Advanced Moderator Materialsmentioning

confidence: 99%

“…High-temperature core concepts traditionally rely on graphite to moderate neutrons since it can sustain high temperatures and displays very low absorption cross-sections. However, it is much less efficient at slowing-down neutrons when compared with a hydrogen-based material [1]. The direct consequence will be to require a high carbon to U-235 ratio in the core.…”

Section: Introductionmentioning

confidence: 99%

Advanced Moderation Module for High-Temperature Micro-Reactor Applications

Miao

Stauff

Bhattacharya

et al. 2020

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Development and deployment of micro-reactors that provide competitive efficiency, prevailing compactness, and inherent safety is an immediate focus of the U.S. nuclear industry. For thermal neutron micro-reactors operating at elevated temperature for optimized efficiency, such as micro molten-salt reactors (MSRs), heat-pipe reactors, and very-high temperature reactors (VHTRs), highperformance moderator based on metal hydride can enhance the neutron economy and therefore achieve reduced weight and enhanced portability. As unclad metal hydride inevitably decomposes at elevated temperature, an enclosure is required for hydride moderator to deliver desired performance at elevated temperatures. Conventional moderator enclosure solutions based on high-temperature alloys introduce extraneous neutron penalty into the micro-reactor, affecting the neutronic benefits provided by the hydride moderator. Additionally, the compatibility between the high-temperature alloy enclosure and the micro-reactor matrix is also a potential issue.

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“…Other references indicate problems with the hydrogen embrittlement of yttrium. This effect appears already for low hydrogen content around and below room temperature [29], and a lack of ductility is described for YH 1.7 at temperatures even above the foreseen operation temperature [30]. Another publication gives view on the possibility of cladding the YH with a protective layer.…”

Section: Remarks On Technological Issues and Reactor Experiencementioning

confidence: 99%

Fine Distributed Moderating Material with Improved Thermal Stability Applied to Enhance the Feedback Effects in SFR Cores

Merk

2013

Science and Technology of Nuclear Installations

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The use of fine distributed moderating material to enhance the feedback effects and to reduce the sodium void effect in sodium-cooled fast reactor cores is described. The influence of the moderating material on the fuel assembly geometry, the neutron spectrum, the feedback effects, the power and burnup distribution, and the transmutation performance is given. An overview on possible materials is provided and the relationship between hydrogen content and thermal stability is described. A solution for the problem of the limited thermal stability of primarily proposed hydrogen-bearing moderating material ZrH1.6is developed by the use of yttrium-mono-hydride. The similarity in the effects reached by ZrH and YH is demonstrated by comparison calculations. The topic is closed by an overview on material properties, manufacturing issues, experience in fast reactors, and a comparison of raw material costs.

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Hydrides as neutron moderator and reflector materials

Cited by 62 publications

References 51 publications

Method to Reduce Long-lived Fission Products by Nuclear Transmutations with Fast Spectrum Reactors

Method to Reduce Long-lived Fission Products by Nuclear Transmutations with Fast Spectrum Reactors

Advanced Moderation Module for High-Temperature Micro-Reactor Applications

Fine Distributed Moderating Material with Improved Thermal Stability Applied to Enhance the Feedback Effects in SFR Cores

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