Proton irradiation effects on beryllium – A macroscopic assessment

Abstract

Beryllium, due to its excellent neutron multiplication and moderation properties, in conjunction with its good thermal properties, is under consideration for use as plasma facing material in fusion reactors and as a very effective neutron reflector in fission reactors. While it is characterized by unique combination of structural, chemical, atomic number, and neutron absorption cross section it suffers, however, from irradiation generated transmutation gases such as helium and tritium which exhibit low solubility leading to supersaturation of the Be matrix and tend to precipitate into bubbles that coalesce and induce swelling and embrittlement thus degrading the metal and limiting its lifetime. Utilization of beryllium as a pion production low-Z target in high power proton accelerators has been sought both for its low Z and good thermal properties in an effort to mitigate thermos-mechanical shock that is expected to be induced under the multi-MW power demand. To assess irradiation-induced changes in the thermal and mechanical properties of Beryllium, a study focusing on proton irradiation damage effects has been undertaken using 200 MeV protons from the Brookhaven National Laboratory Linac and followed by a multi-faceted post-irradiation analysis that included the thermal and volumetric stability of irradiated beryllium, the stress-strain behavior and its ductility loss as a function of proton fluence and the effects of proton irradiation on the microstructure using synchrotron X-ray diffraction. The mimicking of high temperature irradiation of Beryllium via high temperature annealing schemes has been conducted as part of the post-irradiation study. This paper focuses on the thermal stability and mechanical property changes of the proton irradiated beryllium and presents results of the macroscopic property changes of Beryllium deduced from thermal and mechanical tests.

Multi-MW accelerator target material properties under proton irradiation at Brookhaven National Laboratory linear isotope producer

“…4. The as-received materials exhibited no scattering in the tensile test data [5]. For this low proton dose (∼1.2 × 10 20 p=cm 2 ) both materials maintain a significant portion of their original ductility.…”

“…Specifically, beryllium in various grades has been studied [1][2][3][4] under the effects of neutrons for use in nuclear fission or fusion reactors and proton effects [5][6][7][8] on beryllium and AlBeMet (a material metal matrix made of 62% beryllium and 38% aluminum by weight) for accelerator applications (targets and beam windows). Various grades of graphite have been explored over the decades for use as a nuclear reactor moderator material [9][10][11][12][13][14] and target in multi-MW proton accelerators [15,16].…”

Neutronic investigation and activation calculation for CFETR HCCB blankets

“…The packing factor of a Be pebble at 64% is adopted in this blanket to obtain a moderate tritium breeding capability. Tungsten has been chosen as the plasma facing material in this blanket, while Be is also a promising plasma for consideration due to its good thermal properties as well as its favorable post-irradiation behavior [12]. A TBR variation of the two candidates as a function of the FW armor thickness is depicted in figure 5.…”

Atomistic simulations of He bubbles in Beryllium

“…Beryllium (Be) has attracted a lot of attention in the context of applications that involve radiation [1][2][3][4][5][6][7][8] because of the excellent radiation response properties of this material, such as the low atomic number, low neutron-capture cross-section, and high neutron scattering cross-section. For example, Be is used as a neutron moderator in nuclear fission reactors [1][2][3] and it is being considered for the first wall of the ITER nuclear fusion reactor [3][4][5]. Be has been also used as the target material and beam window in high-energy particle accelerators [6][7][8].…”