The effect of neutron irradiation on beryllium oxide

Hickman, B.S.; Pryor, A.W.

doi:10.1016/0022-3115(64)90166-7

Cited by 45 publications

(12 citation statements)

References 13 publications

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“…1 nm is observed after irradiation at 70-100°C to neutron fluence 1.5·10 21 cm -2 [6]. Quite large (10 nm) accumulations of helium atoms were observed only after the irradiated samples were annealed.…”

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confidence: 87%

State of helium in irradiated beryllium

Kosenkov¹,

Posevin²,

Silantiev³

2012

At Energy

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Experimental data are presented on the change of the pycnometric density and unit-cell volume of beryllium irradiated in an SM reactor to neutron fluence 14·10 22 cm -2 . The behavior of the unit-cell volume as a function of the neutron fluence is similar to the data for other metals. This and data on the volume change in beryllium oxide, where a large amount of gas is also formed during irradiation, make it possible to evaluate critically the assertion that helium forms a solid substitution solution. It is proposed that helium is confined in small accumulations.The unique nuclear-physical and physical-mechanical properties of beryllium make this element irreplaceable as a material for neutron moderators and reflectors. Numerous studies of beryllium articles and specially prepared samples irradiated to neutron fluence >10 23 cm -2 (E > 0.1 MeV) have now been performed. The changes in the material properties, information on which is needed to establish safe service lifetimes, have been studied. One such property is swelling -an increase of the volume of an article and decrease of the pycnometric density.It is well known that the swelling of irradiated materials can be substantial. Under irradiation, the density AlGdO 3 , Dy 2 TiO 5 , and BN changes by 6.5, -4.2, and ~30%, respectively [1]. The pycnometric density of diamond decreases to 47% and the unit-cell volume increases by 20% (up to the moment of amorphization) [2]. The masonry graphite at the Leningradskaya nuclear power plant showed a 13% reduction of the pycnometric density and the density measured according to the change in volume of the unit cell. It is known that corrosion resistant steel can swell by 20% under certain conditions. Aside from structural changes swelling can be due to vacancy accumulation and a change of the coordination number and therefore the character of the bonding force at the site of a single defect (vacancy or interstitial), for example, the model of the appearance of "graphite structure motifs" in diamond [3]. In these cases, large swelling was determined by the intrinsic defects of the material -components of Frenkel pairs, which arise as a result of the interaction of fast neutrons with the crystal lattice. Aside from Frenkel pairs, helium and tritium form in beryllium-containing materials. For example, the concentration of helium atoms is 12000 ppm, i.e., 1.2%, under fluence 6·10 22 cm -2 (E > 0.1 MeV) and increases to 1.7% under fluence 13·10 22 cm -2 [4]. Where is this helium? How does it affect swelling?Researchers studying beryllium oxide, which can be used as a reflector and moderator, were also faced with this problem. Extensive research done on BeO at the Research Institute for Atomic Reactors (NIIAR) has shown that 16% swelling under irradiation to fluence 1·10 22 cm -2 (irradiation temperature <200°C) is "solid," because the relative increase of the volume of the material is equal to the relative increase of the unit-cell volume. In addition, there are no grounds for attributing it to helium accumulation. Figure 1 sh...

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confidence: 87%

State of helium in irradiated beryllium

Kosenkov¹,

Posevin²,

Silantiev³

2012

At Energy

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“…For ECO fuels, we have found that 10 vol.% of continuous phase BeO in UO 2 increases the thermal conductivity $50% over standard UO 2 fuel [9]. However, as opposed to the cubic b-SiC, BeO, has an hexagonal crystal structure and exhibits anisotropic crystal growth under energetic neutron bombardment that can lead to microcracking and even pulverization at high doses [10]. This tendency is related grain size, temperature and other factors not fully understood [10].…”

Section: Introductionmentioning

confidence: 96%

“…However, as opposed to the cubic b-SiC, BeO, has an hexagonal crystal structure and exhibits anisotropic crystal growth under energetic neutron bombardment that can lead to microcracking and even pulverization at high doses [10]. This tendency is related grain size, temperature and other factors not fully understood [10]. In addition, there is the production of helium by the n, 2n and the n, a reactions on Be as well as the production of tritium by the (n, a) reactions on 6 Li, but these gas producing reactions are secondary to the irradiation growth problem [11].…”

Section: Introductionmentioning

confidence: 98%

New processing methods to produce silicon carbide and beryllium oxide inert matrix and enhanced thermal conductivity oxide fuels

Sarma

Fourcade

Lee

et al. 2006

Journal of Nuclear Materials

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“…To prevent bypassing of air through nonoperating leg of air supply system Butterfly type, solenoid-operated 3 (see Table 2-XXXIX) Air -65 to +200 (see Table 2-XXXIX) Suitable for flange mounting (see Table 2-XXXIX) (see Table 2 Table 2-XLI) 208 V, 3 phase, 4 wire, 400 cps (see Table 2-XLI) 115 V, 1 phase, 400 cps Thermal type, automatic reset Motor contactors will be mounted on the removable shield package -65 to +200 (see Table 2-XLI) 40. 5 total (see Table 2-XLI) 25.000 2-99 2-100…”

Section: -95mentioning

confidence: 99%

“…Effect of temperature on thermal conductivity of BeO A-38 A- 21 Effect of temperature on specific heat of BeO A-39 A- 22 Effect of temperature on enthalpy change of BeO A-40 A- 23 Effect of temperature on standard enthalpy change of BeO A-41 A- 24 Effect of temperature on standard free energy change of BeO A-42 A- 25 Effect of'temperature on entropy change of BeO A-43 A- 26 Effect of temperature on free energy function (G°- Effect of temperature on compressive strength of 94% theoretical density BeO A-4 9 A-34…”

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confidence: 99%

MCR Preliminary Design Report: Shield.

1964

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The effect of neutron irradiation on beryllium oxide

Cited by 45 publications

References 13 publications

State of helium in irradiated beryllium

State of helium in irradiated beryllium

New processing methods to produce silicon carbide and beryllium oxide inert matrix and enhanced thermal conductivity oxide fuels

MCR Preliminary Design Report: Shield.

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